center72209Chapter 1 00Chapter 1 1571171256086Introduction 00Introduction IntroductionLiquefaction of Gases

center72209Chapter 1
00Chapter 1

1571171256086Introduction
00Introduction

IntroductionLiquefaction of Gases:Change of state of any substance form gaseous state to the liquid state is called liquefaction. As the different states of matter has different quantity of energy of molecules which makes up the substance. So this energy must be given or supplied to or from a substance in order to make its state change. To change the gas to the liquid the heat must be removed. For liquefaction of gases, its molecules must be brought closer because liquids occupy less volume than gases. So, to bring them closer we need to increase the pressure on the gas and lower its temperature to reduce the speed of higher energy molecules. In order to achieve these conditions, we need to know the critical temperature and pressure of the gases.1
Critical temperature:Critical temperature of gas is the temperature which is minimum required to liquefy a gas. The pressure alone will not liquefy a gas until this critical temperature is achieved. It depends upon three factors (size of molecules, shape of molecules & intermolecular forces between the molecules) 1
Critical pressure:Critical pressure is the at least pressure which is necessary for a gas to be liquefied at the critical temperature. 1
Critical volume:The volume occupied by a unit mole of the gas at its critical temperature & critical pressure.

There are generally four methods adopted to liquefy a gas , which are following:
Compression
Making a gas work against an external force
Joule Thomson effect1
Purification of gases:The process in which the impurities from industrial gaseous streams are removed is called purification of gases. The impurities are needed to remove because they not only pollute the atmosphere but also disturbs the efficiency of the production process. Generally the purification methods are: Mechanical, Electrical & physiochemical methods.
Mechanically, by centrifugal force, scrubbing the gas with water, by filtration through fibrous & porous material.

Electrically, by action of forces of high voltage, non uniform electric field like electrical filters
Physiochemical, for removal of gaseous impurities by scrubbing with solvent (absorption), by chemical absorption, by adsorption, physical separation2
History of Purification & Liquefaction of gases:Initial work on the liquefaction of gases was done by English scientist Michael Farady in the initial era of 1820. He liquefied gases at high critical temperatures like chlorine, carbon dioxide, hydrogen bromide and hydrogen sulfide by utilization of pressure only. After this era the scientist found other ways to liquefy the gases. Then in 1869, Thomas Andrews found that every gas has a specific temperature which is its critical temperature, which is minimum required to liquefy it, without the consideration of pressure applied on it. That’s why it is necessary to cool the gas lower to its critical temperature to liquefy it. Before the start of 19th century many scientists had performed experiments on this process. The first to achieve the success were, Davy ; Farady. The mass production of liquefied gases in bulk quantities was done by efforts of Z.F.Wroblewski ; K.S.Olszewski, the two well-known scientists. Sir James Devware has performed liquefaction of air.
Many advanced processes of liquefaction of gases were developed by Lind and many others gave the basic information that is now used in advanced refrigeration systems.
Importance of LiquefactionLiquefaction is a process in which gas or solid is converted into the liquid form. Liquefaction is of great importance in many industrial and chemical processes. Many important gases are converted to liquid form which are used in wide range of useful applications. One of the major use of liquefaction is the liquefaction of air to separate it into its constituents like oxygen, nitrogen and other noble gases. It also finds its application in conversion of hard coal into a liquid form which then used as a replacement to liquid fuels. Liquefaction is also very useful in analysis of basic properties of gas molecules like intermolecular forces. It is used on large scale for storage of gases and for their easy handling as well. Many important gases are liquefied on vast scale for special purposes like liquid oxygen is used in hospitals for artificial respiration, liquid nitrogen is also used utilized in cryosurgery. Liquid chlorine is vastly used in purification of water, sanitation of industrial wastes, sewage and swimming pools, in pulp bleaching and textiles and manufacture of carbon tetrachloride, glycol and numerous other organic compounds as well as phosgene gas. Liquefied carbon dioxide is also used on large scale in food and beverages and also in oil refinery for extraction of more quantity of crude oils and has many used in food industry.

History of Carbon DioxideCarbon dioxide (CO2) was the primary gas to be represented as a distinct substance. In regarding 1640,3 the Flemish chemist Baptist van Helmont discovered that once in a closed vessel he burned charcoal, the mass of the ensuing ash was abundant lower than that of the initial charcoal. His conclusion was that the remainder of the charcoal had been transfigured into imperceptible substance he named a “gas” or “wild spirit”.4

The possessions of carbon dioxide (CO2) were studied carefully in the 1750s, by the J. Black, carefully found that the limestone (calcium carbonate) could be treated with acids to produce a gas, called “fixed air.” He experiential that the fixed air was denser than air and supported neither flame nor animal life. He also carefully found that when it bubbled through limewater, it precipitated in CaCO3. Utilized this wonder to demonstrate that CO2 is yielded by animal respiration and microbial fermentation. 5

In 1772, Chemist J. Priestley from England, printed a paper authorised Impregnating Water with fastened Air within which he delineates a method of dripping acid on chalk so as to provide dioxide of carbon, and forcing gas to dissolve by provocative a bowl of water in touch with the gas. 6

CO2 was 1st liquefied (at elevated pressures) in 1823 by H. Davy and Faraday. The earliest description of solid CO2 was given by A. J. P. Thilorier, who opened a controlled instrumentation of liquid CO2 storage in 1835, solely to seek out that cooling made by quick evaporation of liquid produces a “snow” of solid CO2.

Union Carbide and Dow Chemical produced inhibited, thirty wt. % MEA solution processes for efficient recovery of CO2 present in gases in 1970’s and 1980’s mostly for EOR (Economical-Oil-Recovery) marketplace. As rate of crude oil fall abruptly in 1986, EOR market vanished, these licensors died out. In 1989, Dow Chemical, sold its GAS/SPEC FT1TM Technology to “Fluor Daniel, Inc.” 7
World’s utmost unconventional and complete industrial programs of R&D (started in 1990 and continuing) by “Mitsubishi Heavy Industries, Ltd”. MHI’s patented CO2 capturing from flue gas technology commercially practical since 1999. 8
Physical Properties of Carbon Dioxide11
60007560693300
Structure
Thermochemistry
Critical Point
Triple Point
CO2 Normal Level

CO2 Levels-Dangerous and Extreme
Application of CO2 Chemical’s Precursor In Industry, CO2 is for the most part devoured as a fixing in generation of CH3OH and urea. Few carboxylic-acids subsidiaries (e.g., sodium salicylate), metal bicarbonates and carbonates, set up from CO2.
Foods
CO2 is sustenance added substance utilized as a charge and acridity controller in food Industries, affirmed for utilization in EU (recorded as E-Number E290), Australia, New Zealand and USA (recorded with INS-Number 290).
CO2 pressurization of Pop Rocks, a candy, done at around 580.0 psia. At the point, as set in mouth, breaks down (simply alike other solid confection), discharges gas rises by a discernible pop. Raising operators make batter ascend by creating CO2.
Bread cook’s yeast produces CO2 by maturation of sugars inside the mixture, while substance liveners, for example, preparing powder and preparing pop discharge CO2 when presented to acids or warmed.

BeveragesCO2 is utilized to deliver carbonated sodas and pop water. Customarily, the carbonation in lager and shimmering wine occurred through common maturation, however numerous makers carbonate these beverages with CO2 recuperated from the aging procedure. On account of packaged and egged brew, reused CO2 carbonation is the most widely recognized strategy utilized. Except for British Real Ale, draft lager is normally moved from barrels in an icy chamber or basement to apportioning-taps on bar utilizing compressed CO2, once in a while blended with N2
Wine MakingCO2 as dry ice is regularly utilized as a part of the wine making procedure to chill off packs of grapes rapidly in the wake of picking to help avoid unconstrained maturation by wild yeast.
The primary favourable position of utilizing dry ice over customary water ice is that it cools the grapes without including any extra water that may diminish the sugar fixation in the grape must, and subsequently likewise diminish the liquor focus in the completed wine.
Dry ice is additionally utilized amid the frosty drench period of the wine making procedure to keep grapes cool. The CO2 that outcomes from the sublimation of the dry ice tends to settle to the base of tanks since it is heavier than air. The settled CO2 makes a hypoxic situation which keeps microorganisms from developing on the grapes until the time has come to begin the maturation by coveted yeast’ strain. CO2, likewise utilized to make hypoxic situation for carbonic maceration, procedure utilized to deliver Beaujolais-wine.

Inert GasStandout amongst most ordinarily utilized compacted gasses for pneumatic (pressurized gas) frameworks in convenient weight apparatuses. CO2 additionally discovers use as atmosphere for welding, despite the fact that in welding circular segment, responds to oxidize generally metal. Utilized in car business, regular in spite of critical, prove by the fact, weld completed in CO2 is extra fragile than that complete in extra inactive environments, and such welds joints crumble after some period on account of Production of H2CO3. Utilized as welding gas principally on the grounds that it is a great deal more affordable than more latent gasses, for example, argon or helium.

Fire ExtinguisherCO2 quenches flame, some fire dousers, particularly those intended for electrical flames, contain fluid CO2 underweight. CO2 quenchers function admirably on little combustible fluid and electrical flames, yet not on normal flammable flames, on the grounds that in spite of the fact that it prohibits oxygen, it doesn’t cool the consuming substances essentially and when the CO2 scatters they are allowed to burst into flames upon introduction to air oxygen.
CO2 has likewise been broadly utilized as a smothering specialist in settled fire security frameworks for neighborhood use of particular risks and aggregate flooding of an ensured space. Worldwide Maritime Organization principles additionally perceive CO2 frameworks for flame assurance of motor room and ship holds. CO2 built fire security framework has been connected to a few casualties, since it doesn’t bolster life in the fixations used to douse fire (40% or something like that), be that as it may, it is not thought to be harmful to people. A survey of CO2 frameworks recognized 51 accidents in the vicinity of 1975, triggering 72 casualties and 145 were injured.
Solvent CO2 (Super Critical)Fluid CO2 is decent dissolvable for some lipophilic natural mixes and, utilized to expel caffeine through espresso. CO2 has pulled in consideration in pharmaceutical and substance handling ventures as less harmful contrasting option to extra conventional solvents, for example, organo chlorides. Also, utilized by some laundry.
Applications in Biology and AgricultureAt high conc. (100 times concentration at atmospheric condition, or more prominent), CO2 is lethal to creature life, raising fixation to 10,000.0 ppm or greater for a few hrs will dispose of nuisances, for example, whiteflies and creepy crawly parasites in a Green House-GH. CO2 is utilized as a part of nurseries as fundamental carbon hotspot for Spirulina green growth. For medication, CO2 up and about to 5.0 % (130 times concentration at atmospheric condition) is mixed with O2 for incitement of breathing after apnea, to balance out CO2/O2 adjust in lifeblood. Recommended that CO2 from control era be risen to lakes, to develop green growth, later changed over to biodiesel-fuel.

Recovery of OilCO2 is utilized for EOR, give a jab into producing-oil reservoir, typically underneath supercritical-conditions. This sort of generation can expand unique oil recuperation by 7 for every penny to 23 for each penny promote from essential extraction. It goes about as both a pressurizing specialist and, when disintegrated into the underground raw petroleum, essentially decreases its thickness, empowering the oil to stream all the more quickly by earth to evacuation well. For develop oil fields, broad pipe systems are utilized to convey CO2 to infusion focuses.
RefrigerantSolid and Fluid CO2 are essential refrigerant, particularly for food industries, where utilized amid capacity of dessert, transportation and other solidified sustenance. Solid CO2 is named “dry ice”, utilized for little shipments, wherever refrigeration hardware is costly. Strong CO2 is dependably underneath ?78.5 °C, at customary pressure(atmospheric), paying little mind to the air temperature.
Fluid CO2 (industry classification R-744 or R744), utilized as refrigerant preceding disclosure of R-12, may appreciate renaissance because of way, R-134a adds to environmental change. Physical properties, profoundly positive for refrigeration, cooling and warming activities, having large volumetric cooling limit. Because of its high-pressure operation up to 1880 psia, CO2 frameworks require exceedingly safe segments which now been created for large scale manufacturing for numerous segments. In vehicle aerating and cooling, in over 90% of every single driving condition for scopes higher than 50°, R744 works more productively than frameworks utilizing R-134a.
Its ecological favourable circumstances (GWP of 1, non-ozone draining, non-lethal, noncombustible) in future, could make it working liquid to supplant momentum HFCs in autos, stores, boiling water warm pumps, among others. Coca-Cola has handled CO2-based refreshment coolers and the U.S. Armed force is keen on CO2 refrigeration and warming innovation. The worldwide car industry is required to settle on the cutting-edge refrigerant in auto aerating and cooling.

Market Survey
Figure SEQ Figure * ARABIC 1. market survey
PAKISTAN LCO2 MARKET
CO2 is mostly liquefied in order to lessen its concentration in atmosphere. This is achieved in compliance with the environmental regulations.

LCO2 PRODUCTION
Pakarab 192TPD
Linde Gas 83TPD
Chitral oil and Ghee 75TPD
Habib Sugar Mills 49TPD
Colony Sugar Mills 45TPD
United Gases 20TPD
LCO2 CONSUMER
Coca Cola 63000TPY
Pepsi37000TPY
Other Beverages 25000TPY
Other Industry 18000TPY
Food Industry 10000TPY
Oil Refinery5000TPY
Seasonal Consumption of LCO2
50% of the total LCO2 produced is sold in months of May, June, July and August
35% LCO2 in Oct, Sep, March,April10% LCO2 in Nov, Dec, Jan, Feb
Capacity of Plant
Capacity selection basically depends upon the demand for that particular object. We have selected the capacity of plant as 200TPD.
LCO2 Temperature = -20 C
Pressure = 21 bar
Plant LocationFollowing factors should be considered while selecting the plant site.

Raw Materials Availability.

The source of raw material plays a most important role while selecting plant site. If the location of raw material source is near to the plant site it will reduce the transportation and storage cost.

Markets.

The cost of the product distribution and the time required for shipping that product greatly depends upon the market. Plant should be situated in that area which is near to the market because buyer purchase product from nearby market. By-product and major final product requires market.

Energy Availability
Power and steam are the most vital need of every industry. Plant site should be near to large hydroelectric installation. Energy supply should readily and easily available to plant this will reduce various cost.

Climate.

The plant site should be selected where climate is favorable. Cold areas are mostly not suitable for plant. Excess of humidity and extreme of hot and cold weather can affect the plant operation and may enhance the cost of operation.

Transportation facilities.

Most of the large industries transport their final products using water, railroads and highways. Plant site should be selected in such a way that at least two of the transport facilities should be available to plant site. This will save transportation cost. Transportation facilities should be available for workers also.

Water Supply
A large quantity of water for cooling, washing, steam generation and as a raw material is used by most of the process industries. Therefore, plant should be located in that area where water is readily available. Plant site should be near large river or lake so that water is easily available.
Waste Disposal
In past industries have to face legal restrictions for disposing of waste materials. Therefore, plant site selected should have adequate capacity and facilities for properly disposing waste material. While selecting plant site various waste disposal methods should be considered. Waste should be disposed of in a proper way.

Labor Supply
Plant site should be selected by considering the factor that type and supply of labor is easily available. It should be noted that the site chosen for plant should be that area where labor is easily available and at lowest wages.

Taxation and Legal Restriction
Site should be selected by considering the factor that like tax rates and various legal restriction. In some areas there are many restrictions imposed by Govt. Sometimes property taxes are high. So while selecting plant site it should be consider that tax rates and legal restrictions should be minimum.

Site Characteristics
There are some characteristics of site that should be consider while selecting plant site like topography of land, soil structure, construction cost, living conditions and future changes.

Flood and Fire Protection
It should be considered that site selected should be protected from flooding and fire. Sometimes industrial plants are located near large rivers so there is a risk of flood. Regional history of the site should be studied carefully.

Community Factors
Community factors effect location of plant. Cultural facilities of the community plays important role in growth. Different recreational activities should be available near plant site. It these facilities are not available it becomes burden for plant site to provide such facilities.

Selection of Plant Site There are various factors involved in selecting the plant site which are as follow
Raw Materials
Markets
Energy Supply
Climate
Transportation
Water Supply
For initial survey for selecting plant site first four factors should be taken into account. Thus on the basis of these factors like raw material, markets, energy supply and climate acceptable location can easily be selected.
2035629241028Chapter 2
00Chapter 2

38100020683Process Selection and Process Description
00Process Selection and Process Description

Process Selection and Process DescriptionMethods of LiquefactionIn general gases can be liquefied by one of the three general methods:
By compressing the gas at temperatures less than its critical temperature.

By making the gas do some kind of work against an external source, causing the gas to lose energy and change to liquid state.
By Joule-Thomson effect.
In the first approach, the application of pressure alone is sufficient to cause a gas to change to a liquid. For example, ammonia has a critical temperature of 406K (271.4 F 133 C). This temperature is well above room temperature, so it is relatively simple to convert ammonia gas to the liquid state simply by applying sufficient pressure. At its critical temperature, that pressure is 112.5 atmospheres
A simple example of the second method for liquefying gases is the steam engine. The principle on which a steam engine operates is that water is boiled and the steam produced is introduced into a cylinder. Inside the cylinder, the steam pushes on a piston, which drives some kind of machinery. As the steam pushes against the piston, it loses energy. That loss of energy is reflected in a lowering of the temperature of the steam. The lowered temperature may be sufficient to cause the steam to change back to water.

In this method the gas is first pumped into a container under high pressure. The container is fitted with a valve with a very small opening. When the valve opened, the gas escapes from container and expands quickly. At same time its temperature drops. In some cases, the cooling that occurs during this process may not be sufficient to cause liquefaction of the gas. However, the process can be repeated more than once.
Here, we have made use of compression process for liquefaction of CO2.
Polytropic compression is being employed.

Basically there are two technologies that are being employed for liquifaction of co2.

American technology
German technology
The standard for liquefaction of CO2 is 99.99 % pure .In selection of any process the first most important aspect is purity of product. The more the purity the more consistent is the product.

We have selected American technology for the following reasons
Purity
The final purity level through this technology is 99.997% pure which makes this technology very better than others. As main concern of any industry is purity so we have selected it as it provides better purity than others.

Advance technology
The american technology is designed on latest parametes. It is the most latest technology for liquefaction of co2 around the world.12
Features
Multistage compression
This employs multistage compression. The benefit of this is that it makes it easily possible to reach the critical pressure which is required for liquefaction.

Polytropic compression
It employs polytropic compression which is very efficient. As it compresses than cools then again compresses. So makes it efficient compression
Dryer
The other main feature of this technology is that it employs the dryer that is of latest technology and is efficient upto 95% . It is of dessicant type dryer.12
Process Introduction
Product: LCO2 for food and industrial use

CO2 is stored and transported in liquid form.
CO2 must be purified to meet product specifications that will allow its use in food and other applications.

Feedstock: VCO2 with various impurities
To produce LCO2, the raw gas must be compressed (19 bar), dried (to prevent the formation of water ice), and refrigerated (cooled to –28C).
To remove impurities from the feedstock, the raw gas is scrubbed with water and passed over adsorbents. In addition, the LCO2 is stripped of dissolved gases.
To produce LCO2: The feedstock is:
Chilled in the low pressure precooler to condense water vapor from the gas stream so that the water does not condense out in the oil of the low or high stage CO2 compressors.
Passes through the low pressure knock out drum to separate the condensate (liquid water) from the gas so liquid water does not enter the low stage compressors.
Compressed in the low stage compressors (5.9 bar). This is the first of two stages of compression up to 19 barg.
Cooled in the intercooler to permit efficient compression in the high stage compressor.
Passes through the interstage knock out drum to separate any condensate (liquid water) from the gas so liquid water does not enter the high stage compressor
Compressed in the high stage compressor (19 barg) the pressure desired for liquefaction.Purified in the scrubber
Chilled in the high pressure precooler to condense water vapor from the gas stream so that water vapor removal requirement of the dryer is reduced.
Passes through the high pressure knock out drum to separate the condensate (liquid water) from the gas so liquid water does not enter the dryer.
Has water removed in the dryer to prevent the formation of water ice in the CO2 condenser.
Refrigerated and partially condensed in the CO2 condenser to produce LCO2. ? Passes through the disengaging chamber to separate entrained vapor CO2 and non- condensable impurities from the condensed liquid and provides a liquid head for the stripper tower feed pump
LCO2 is pumped through the stripper to be purified
The liberated gases, along with CO2 vapor, pass through the reflux condenser where a portion of the CO2 is re-condensed.
The remaining CO2 and non-condensable gases exit the top of the stripper.
This impure vapor stream then flows through the non-condensable purge assembly and then to atmosphere.
The pure CO2 vapor which enters below the packed bed is generated in the reboiler pure liquid CO2 flows by thermosyphon action from the stripper’s flooded sump to the reboiler. The reboiler vaporizes the liquid CO2 by a flow-regulated stream of refrigerant to create a constant minimum supply of stripping CO2.
Purified LCO2 product is pumped through to the storage tank.
NH3 evaporating at two different temperatures is used to chill (+1oC) and refrigerate (-28oC) the system. These temperatures correspond to intermediate and low pressure sections 0f the NH3 system:
+1oC NH3 (intermediate pressure section) is obtained by flashing LNH3 from the receiver down to approximately 3.5 barg in the low and high pressure precoolers
-28oC NH3 (low pressure section) is obtained by flashing LNH3 from the intermediate pressure system to approximately 0 barg in the CO2 condenser and reflux condenser
Purification of the CO2 is accomplished by:

Once through (water is not re-used) scrubbing of the CO2 with deaerated water for bulk removal of alcohols (methanol and ethanol) and aldehydes (acetaldehyde ).
Activated alumina and molecular sieve media in the dryer towers to adsorb water. The dryer consists of two towers. One tower is on line purifying CO2 while the other tower is being thermally regenerated.
Removing the small quantities of non-condensible gases (H2, N2, O2) which dissolve in the LCO2 exiting the CO2 condenser by stripping these gases from the LCO2 in the stripping tower.
PROCESS ; EQUIPMENT OVERVIEW
Raw gas is delivered to the plant at 1.07 bar and 60C. The gas is chilled in the low pressure precooler and the resultant process condensate is removed in the suction knock out drum. The vapor is then compressed, in two stages, to approximately 19 bar. Oil lubricated screw compressors utilizing food grade oil are used. Two low stage CO2 compressors operate in parallel. The gas exiting the low stage compressors passes through a common intercooler and knocks out drum prior to entering the single high stage compressor.
The gas exiting the high stage CO2 compressor passes through an external coalescing filter for oil removal before entering the structured packed scrubber where the condensate drops out and water soluble impurities are removed from the gas by a deaerated make up water stream.
The gas exiting the scrubber is then chilled in the high pressure precooler and the condensate removed in a knock out drum to reduce the quantity of water to be removed in the dryer. The dryer contains both activated carbon and desiccant to remove certain oxygenated hydrocarbons and water vapor. CO2 gas from the head space of the static liquid CO2 storage tanks is utilized for dryer purge gas. The dry gas exiting the dryer then passes through a dust filter and enters the CO2 condenser. The gas entering the CO2 condenser is partially condensed. The liquefied CO2 gravity flows to the liquid inlet of the Disengaging Chamber vessel while the non-condensable gas is directed to the inlet / bottom of the Reflux CO2 condenser mounted at the top of the stripper tower.
Non-condensibles dissolved in the LCO2 entering the stripper are stripped utilizing pure CO2 vapor generated in the reboiler. LCO2 exiting the stripper is pumped to the static liquid CO2 tanks at approximately –21C and line pressure up to 21.4 bar.
The screw compressor oil coolers are water cooled whereas the gas chilling and condensing is done with NH3.The water cooling heat load is rejected to the customer supplied water cooling system, whereas the NH3 heat load is rejected through the evaporative type condenser. Nominal 1C coolant for use in the precoolers and nominal –31C coolant for use in the CO2 condenser and reflux condenser are provided by mechanical refrigeration utilizing oil lubricated NH3 screw compressors with a side port which accepts 1C vapor NH3.

Process ; Equipment Detailed DescriptionLow Pressure Cooling SkidLp Precooler:The feed gas coming from ammonia plant goes to LP precooler. It is a shell and tube exchanger with CO2 in tubes and ammonia in the shell side.

Purpose:The main purpose of LP precooler is to remove sufficient water vapour from CO2 stream so that water will not condense in CO2 compressors.

Working of LP precoolerNH3 at 1C is used to cool feed gas to 7C. The temperature of NH3 is maintained above 0C to prevent formation of water ice on CO2 side of exchanger. Heat transfer takes place and CO2 is cooled. Ammonia comes from storage. Expansion occurs but properly expansion takes place in LP precooler shell.So high level of ammonia may trip compressors to stop entry of ammonia in LP precooler.

Effect:If it happens these vapors may condense in compressors and cause corrosion.

PCV:On top of receiver there is a PCV and pressure gauge. They control the ammonia pressure of 3.5 bar. Then ammonia is send back to compressors.

Oil Pot:Ammonia has some oil drops from compressor. There this oil is removed. The oil starts to settle at the bottom which increases liquid level in shell that can cause less expansion of ammonia.It’s having a heater which removes entrapped ammonia from oil. Then it goes to receiver and then to compressors. The oil may sent back to compressor or if not clear then drained.

Knock Out Drum:Its main function is to remove of liquid from gas so that it does not goes to compressor.The water condensed in LP precooler is collected in sump and drained to sewer through LCV. At the top the moisture is removed from the gas stream in demister pad as gas stream exits the tower and enters low stage compression. Its having LSLL and LSHH to indicate water level in drum.

Low Stage Co2 Compressors
These are single stage oil lubricated screw compressors.

Working Mechanism:The gas from knock out drum inters at suction of compressor with constant injection of oil. Gas is compressed between a driven and undriven rotor. There the gas is compressed to 5.8 bar at 180°F then the oil is separated from the gas as it passes through the separator and a demister and gas goes to intercooler.

Oil Purpose:1 Seal the gap between the rotors to permit compression2 Cool the gas as it is compressed3 lubricate the compressor
Oil Nature:Food grade oil is used so it could not affect product quality. 
Oil circuit of low stage compressor:The oil is separated in separator by action of gravity and mists of oil is removed in demister. Then from bottom line it passes through a ball valve and a bucket type strainer. Then there are two lines one is of NRV and one is pump.
Pump:At start the oil is circulated by pump which is gear type.NRV: When pump makes enough discharge pressure the pump trips and oil is circulated by NRV.

PSV:There is a PSV line with the NRV line. If discharge pressure increases the PSV opens and sends the oil back to suction of pump in this way it maintains it.

MOV:Now it plays main role in the oil circuit. Its function is to maintain the oil temperature at 65C. So if required MOV sends some oil to oil cooler.

Oil Cooler:The oil cooler is a shell and tube heat exchanger having oil in shell and water in tubes. It cools the oil to maintain temperature of 65C.Then the oil stream from separator and oil cooler are mixed to form 65C and passes through filter.

Oil Filter:After mixing the oil passed through filter and is filtered there and goes to the suction of compressor and this cycles continues like this.There are 5 PSV’s, 5 TE’s and 4 PT’s on compressor to control excess pressure, temperature and pressure.

Intercooler
Gas leaving low stage compressor is cooled in intercooler. It is shell and tube heat exchanger having CO2 in tubes and water in the shell side. Heat transfer takes place and CO2 is cooled and moisture is reduced so that it does not enter the High stage compression. The gas leaving the intercooler has temperature of 43C
Knock Out Drum:
Its main function is to remove of liquid from gas so that it does not goes to compressor.The water condensed in intercooler is collected in sump and drained to sewer through LCV. At the top the moisture is removed from the gas stream in demister pad as gas stream exits the tower and enters high stage compression. It’s having LSLL and LSHH to indicate water level in drum.

High Stage Co2 Compressors
These are single stage oil lubricated screw compressors.

Working Mechanism:The gas from knock out drum inters at suction of compressor with constant injection of oil. Gas is compressed between a driven and undriven rotor. There the gas is compressed to 19.3 bar at 180°F then the oil is separated from the gas as it passes through the separator and a demister and gas goes to intercooler.

Oil Purpose:1 Seal the gap between the rotors to permit compression2 Cool the gas as it is compressed3 lubricate the compressor
Oil Nature:Food grade oil is used so it could not affect product quality. 
Oil Circuit Of Low Stage Compressor:The oil is seperated in seperator by action of gravity and mists of oil is removed in demister. Then from bottom line it passes through a ball valve and a bucket type strainer. Then there are two lines one is of NRV and one is pump.

Pump:At start the oil is circulated by pump which is gear type.

NRV:When pump makes enough discharge pressure the pump trips and oil is circulated by NRV.

PSV:There is a PSV line with the NRV line. If discharge pressure increases the PSV opens and sends the oil back to suction of pump in this way it maintains it.

MOV:Now it plays main role in the oil circuit. Its function is to maintain the oil temperature at 65C. So if required MOV sends some oil to oil cooler.

Oil Cooler:The oil cooler is a shell and tube heat exchanger having oil in shell and water in tubes. It cools the oil to maintain temperature of 65C.Then the oil stream from separator and oil cooler are mixed to form 65C and passes through filter.

Oil Filter:After mixing the oil passed through filter and is filtered there and goes to the suction of compressor and this cycles continues like this.There are 5 PSV’s, 5 TE’s and 4 PT’s on compressor to control excess pressure, temperature and pressure.

Coalescing Filter:
Gas leaving HS Compressor passes through this filter to remove any traces of oil and make the gas completely oil free. Then it goes to scrubber.

Scrubber
It uses the technique of scrubbing which is a separation technique. With the help of potable water the water soluble impurities are removed in the scrubber.

Principle Involved:The principle applied in scrubber is absorption as water absorbs water soluble impurities.

Mechanism:The scrubber is a structured packed bed. The water enters from the top while the gas enters from bottom. Counter current action takes place and water absorbs impurities like ethanol, methanol, aldehydes and ketone etc and gas then leaves at 85C.There is FCV to control water rate so that it can contact to gas according to set point because if water level reduces it may not remove the required level of impurities and it also has a LCV to maintain level then it goes to HP precooler.

High Pressure Cooling Skid
Hp Precooler:It is a shell and tube exchanger with CO2 in tubes and ammonia in the shell side.

Purpose:The main purpose of HP precooler is to remove sufficient water vapour from CO2 stream to minimize the duty of dryer
Working Of Hp PrecoolerNH3 at 1C is used to cool feed gas to 7C. The temperature of NH3 is maintained above 0C to prevent formation of water ice on CO2 side of exchanger. Heat transfer takes place and CO2 is cooled. Moreover its working is same as LP precooler.

Oil Pot:Ammonia has some oil drops from compressor. There this oil is removed. The oil starts to settle at the bottom which increases liquid level in shell that can cause less expansion of ammonia.It’s having a heater which removes entrapped ammonia from oil. Then it goes to receiver and then to compressors.The oil may sent back to compressor or if not clear then drained.

Knock Out Drum:Its main function is to remove of liquid from gas so that it does not goes to dryer.The water condensed in HP precooler is collected in sump and drained to sewer through LCV. At the top the moisture is removed from the gas stream in demister pad as gas stream exits the tower and enters high stage compression. It’s having LSLL and LSHH to indicate water level in drum.

Coalescing PrefilterIts function is to remove the final trace amounts of liquid water present in the gas exiting the high pressure knock out drum. This prevents the desiccant in the dryer from loading with liquid water instead of water vapor. It also prolongs the life of desiccant.

Dryer
Type:It is thermal type dryer
Main Components:1 Pre Filter2 Dryer Vessels3 After Filter
Pre Filter:Gas passes through pre filter which removes water droplets from gas . These droplets can reduce dryer efficiency and increase dew point of final product.

Dryer Vessels:
There are two dryer vessels one is in use while the other is thermally regenerated.

Principle:This works on principle of adsorption.

Mechanism:The vessel consists of three bed 1 Activated carbon2 Activated Alumina3 Molecular sieve
The gas first passes through the activated car which adsorbs higher weight hydrocarbons and the odour as well. Then it passes through the activated alumina and molecular sieve which removes the moisture and they preferentially adsorb water over other compounds.

After Filter:Then it passes through the after filter which removes dust from gas or desiccant particles.

Regeneration 
It is of prime importance for proper functioning of the dyer. It takes 8 hours to regenerate the dryer1 minute depressurization160 minutes heating50 minutes cooling/sweeping19 minutes repressurization
250 minutes standby
Depressurizing:
Prior to thermal regeneration the tower must be depressurized. Gas from the offline tower flows through the depressurization valve, across orifice to atmosphere. Failure in this step prevents the next step from taking place.

Heating:Heating is done by electric heaters placed inside the dryer at the bottom. The desiccant is heated to drive off the adsorbed moisture contents. The heating is terminated as temperature rises to 200°F.

Cooling:After heating, cooling starts. Cooling is done naturally. During cooling sweeping is also done in dryer by passing CO2 gas from the bottom to the top. This gas is drained from the top because of larger moisture contents.

Repressurization:
This is also very important to repressurize the system because the coming stream is at 270 PSI. This is done to avoid1 Thermal shock2 Mass transfer shockThese can damage the desiccants that’s why it is necessary to repressurize the system.

Stand By:Then the system is on stand by for next 250 minutes and regeneration completes and ready to be used.

Co2 Condensor
Purpose:The purpose of CO2 condenser is to recover liquid CO2 from feed gas . This is a shell and tube exchanger with refrigerant accumulator vessel.It works same like LP and HP precoolers. Ammonia leaving reboiler and reflux condenser is taken as the inlet of CO2 condenser. Ammonia leaves at -28C and goes to compressorDue to sudden decrease in temperature CO2 gas is partially condensed and goes go disengaging chamber CO2 temperature is -27C.The vapour exiting the CO2 condenser will contain CO2 and and high concentration of non-condensable gases which should be removed in order to get product specifications that’s why it is further processed in stripper section
Oil Pot: It also has oil pot which works similar to LP and HP oil pots
Disengaging Chamber
Purposr:It separates liquid and vapour CO2 through the action of gravity and provides liquid head for stripper tower feed pumps.

Mechanism:The feed enters the chamber and through the action of gravity liquid falls down in sump while vapours are at top. There are two sliding vane pumps one is in working while one is standby they are used to send the liquid to stripper and back to disengaging chamber. Then both liquid and vapour streams enter the stripper section.

LCo2 Stripper
Stripper is the last step of purification and liquefaction of CO2 plant. There the non-condensable gases like H2, N2, and O2 are removed.This system consists of a wire mesh structured packed bed tower, CO2 reboiler and LCO2 product pumps.

Principle:It strips off the non-condensable through the action of adsorption.

Mechanism:The vapor CO2 and liquid CO2 enters the stripper. Due to gravity liquid falls in sump and maintains a level of 50% while vapors go to reflux condenser. Reflux condenser is a shell and tube exchanger. Ammonia is in tubes while vapor CO2 is in shell side. The liquid from sump enters the reboiler. Reboiler is also a shell and tube exchanger mounted vertically. The ammonia comes from compressor line and when leaves the reboiler it enters the condenser. The ammonia is in tubes while CO2 in shell side. As liquid CO2 at -28C enters the reboiler it vaporizes and temperature becomes -22C and leaves the reboiler and enters the stripper and moves upward making counter current contact with coming CO2 and strips off the non-condensable gases by adsorbing them and then passes through reflux condenser which will condense the CO2 vapors and let the non condensible to escape from vent. The ammonia comes from HP precooler in reflux condenser and after use goes to condenser. Product LCO2 exiting the stripper sump is transferred to the LCO2 storage tank by the LCO2 product pump which are sliding vane type. There are also solenoid valves used to prevent cavitation at start up.

Storage TanksTwo storage tanks are there to store and deliver LCO2. Each storage tank has the capacity of 250MT. Two refrigerant units are used to cool down compressed CO2 to keep it in liquid form.

Refrigeration Cycle
The ammonia refrigeration cycle consists of these main components1 Compressors2 Evaporative Condenser 3 Receiver4 Expansion valves5 Evaporator
MechanismCompressors:
The ammonia from CO2 condenser, LP and HP comes the ammonia compressors that are single stage screw compressor. They compress the ammonia gas to use for refrigeration in LP, HP precooler and CO2 condenser. The ammonia leaves the compressor at 70 to 70C at 10 to 12 bar. These vapors go to evaporative condenser. These compressors work on the same principle as the CO2 compressors discussed previously.

Evaporative Condenser:Ammonia is condensed in this prior to returned to the ammonia receiver. It comprises of 2 cells with a separate water basins. Each cell has one ammonia coil and one fan, water pump, water make up fload valve, over flow, drain, and electric pan heater. 
Mechanism:The ammonia refrigerant vapor from the compressors is circulated through the coil of the evaporative condenser. Heat from the refrigerant is dissipated through the coil tubes to the water cascading downward over tubes. Air is drawn in through the air inlet louvers at the base of condenser and travels upward over the coil opposite the water flow. A small portion of water is evaporated which removes the heat, condensing the vapor ammonia to liquid. The warm moist air is drawn to the top of the evaporative condenser by fan and is discharged to the atmosphere. The remaining water falls to the sump and recirculated by pump. The condensed liquid flows to the liquid receiver vessel.

Nh3 ReceiverLNH3 is drawn from the receiver to the LP and HP precoolers.

Expansion Valves:After receiver ammonia expands from three vales to achieve final temperature of 1C. First expansion occurs through solenoid valve on top of receiver then through LCV and then through manual valve.

Evaporator:When it enters the receiver of LP precooler evaporation takes place and again returned to the compressors. This is how ammonia refrigeration cycles works.

Design BasisTable SEQ Table * ARABIC 1. Design basis
COMPONENT FEED GAS (%) PRODUCT LIQUID (%)
Carbon Dioxide 78.92 99.94
Water 18.74 0
Carbon Monoxide 0.004063 0.000204
Niterogen0.879 0.012
Argon 0.15 0.046415
Hydrogen 1.3 0
Acetaldehyde 0.004 0
Methanol 0.0055 0
Benzene 0.000001 0

Figure SEQ Figure * ARABIC 2. PFD of CO2 Liquefaction Plant

Description of Process Flow Diagram of CO2 liquefaction plant
Table SEQ Table * ARABIC 2. Description of PFD
Stream no. Description
1 Raw CO2 gas from NH3 plant
2 CO2 gas to LP knock out drum
3 CO2 gas to low stage compressors
4 CO2 gas to intercooler
5 CO2 gas from high stage compressor
6 CO2 gas from scrubber
7 CO2 gas from HP precooler
8 CO2 gas to dryers
9 CO2 gas to CO2 condenser
10 Non condensable gases to reflux condenser
11 CO2 liquid to scrubber
12 CO2 liquid for pressure balance
13 CO2 liquid to reboiler
14 CO2 gas from reboiler
15 CO2 product for pressure balance
16 CO2 product
17 Non condensable gases to atmosphere
18 NH3 liquid to LP precooler
19 NH3 liquid to HP precooler
20 NH3 gas to compressor inlet
21 NH3 gas to compressor inlet
22 NH3 liquid to reflux condenser
23 NH3 liquid to CO2 condenser
24 NH3 gas to reboiler
25 NH3 liquid to CO2 condenser
26 NH3 gas to compressor inlet
27 NH3 liquid to evaporative condenser
28 To drain
29 To drain
30 Potable water inlet
31 Potable water outlet
32 To drain
33 Water to evaporative condenser
34 Water from evaporative condenser
35 Cooling water inlet
36 Cooling water outlet
37 Oil back to high stage compressor
38 NH3 liquid to storage

186145785906Chapter 3
00Chapter 3

947058171994Material and Energy Balance
00Material and Energy Balance

Material and Energy Balance: Material Balance On LP Cooler4895850857250 10608 kg/hr08 kg/hr00 10608 kg/hr08 kg/hr-180975924560 10608 kg/hr08 kg/hr00 10608 kg/hr08 kg/hr
Figure SEQ Figure * ARABIC 3. LP Cooler
It is a shell and tube heat exchanger with CO2 in the tubes and ammonia in the shell side. The main purpose of LP cooler is to remove sufficient water vapour from CO2 stream so that water will not condense in CO2 compressor.
Input=Output Feed=Product
Total Flow rate= 10608 kg/hrMolar flow rate=241 kmol/hrInput Stream
Table SEQ Table * ARABIC 3. Material Balance On LP Cooler
Component Kg/hrKmol/hrMol. Frac.

CO2 8274.24 188.05 0.789
H2O 1986.87 110.38 0.1873
C6H6 1.0608*10^-4 1.36 * 10-6 1 * 10-8
H2 137.904 68.95 0.013
Ar16.36 0.409 1.543 * 10-3
CH4O 0.69 0.021 6.51 * 10-5
N2 92.18 3.29 8.69 * 10-3
CO 0.424 0.015 4 * 10-5
C2H4O 0.430 0.0097 4.06 * 10-5
Output Stream
Component Kg/hrKmol/hrMol. Frac.

CO2 8274.24 188.05 0.789
H2O 1986.87 110.38 0.1873
C6H6 1.0608*10^-4 1.36 * 10-6 1 * 10-8
H2 137.904 68.95 0.013
Ar16.36 0.409 1.543 * 10-3
CH4O 0.69 0.021 6.51 * 10-5
N2 92.18 3.29 8.69 * 10-3
CO 0.424 0.015 4 * 10-5
C2H4O 0.430 0.0097 4.06 * 10-5
Total Material In = 10608 Kg/hrTotal Material Out= 10608 Kg/hr
Material balance on compressorsright1400175 9758 kg/hr08 kg/hr00 9758 kg/hr08 kg/hr-47625781050 9758 kg/hr08 kg/hr00 9758 kg/hr08 kg/hr
Figure SEQ Figure * ARABIC 4. Compressors
Compressors are single stage screw compressor. They compress the ammonia gas to use for refrigeration in LP, HP precooler and CO2 condenser.

Input=Output
Feed=Product
Total Flow rate= 9758.02 kg/hrMolar flow rate=241 kmol/hrCompressor 1= 4879.01 kg/hrCompressor 2= 4879.01 kg/hrInput Stream
Table SEQ Table * ARABIC 4. Material balance on compressors
Component Kg/hrKmol/hrMol. Frac.

CO2 94116.4 214 0.965
H2O 96.6 5.36 0.0099
C6H6 9.75*10^-5 1.25*10^-6 1 * 10-8
H2 146.3 73.18 0.015
Ar18.34 0.45 0.00188
CH4O 0.77 0.024 7.9 * 10-5
N2 102.4 3.65 1.05 * 10-2
CO 0.483 0.017 4.951 * 10-5
C2H4O 0.478 0.10 4.9 * 10-5
Output Stream
Component Kg/hrKmol/hrMol. Frac.

CO2 94116.4 214 0.965
H2O 96.6 5.36 0.0099
C6H6 9.75*10^-5 1.25*10^-6 1 * 10-8
H2 146.3 73.18 0.015
Ar18.34 0.45 0.00188
CH4O 0.77 0.024 7.9 * 10-5
N2 102.4 3.65 1.05 * 10-2
CO 0.483 0.017 4.951 * 10-5
C2H4O 0.478 0.10 4.9 * 10-5
Total Material In = 9758.02 Kg/hrTotal Material Out= 9758.02 Kg/hrMaterial Balance on dryer-25717575565 9618 kg/hr08 kg/hr00 9618 kg/hr08 kg/hr49815752733040 9615 kg/hr08 kg/hr00 9615 kg/hr08 kg/hr
Figure SEQ Figure * ARABIC 5. Dryers
It is thermal type dryer. Its main components are prefilter, dryer vessels and after filter. Gas passes through pre filter which removes water droplets from gas. These droplets can reduce dryer efficiency. There are two dryer vessels one is in use while the other is thermally regenerated. This works on principle of adsorption. The after filter removes dust from gas or desiccant particles.

Total Flow rate feed= 9618.02 kg/hrMolar flow rate=225 kmol/hrEfficiency= 90%
Moisture removed= 0.03%
Moisture removed= 9618.02*.0003*0.9 = 2.596 kg/hrFlow rate of product = 9618.02 – 2.596 = 9615.42 kg/hrMolar Flow rate= 224.0952 kmol/hrInput Stream
Table SEQ Table * ARABIC 5.Material Balance on dryer
Component Kg/hrKmol/hrMol. Frac.

CO2 9560.07 217.27 0.994
H2O 0 0 0
C6H6 0 0 0
H2 0 0 0
Ar4.462 0.111 0.000464
CH4O 0.626 0.019 6.51 * 10-5
N2 1.15 0.041 1.20 * 10-4
CO 0.0192 6.87*10^-4 2 * 10-6
C2H4O 0 0 0
Output Stream
Component Kg/hrKmol/hrMol. Frac.

CO2 9557.72 217.22 0.994
H2O 0 0 0
C6H6 0 0 0
H2 0 0 0
Ar4.46 0.111 0.000464
CH4O 0.625 0.019 6.51 * 10-5
N2 1.15 0.041 1.20 * 10-4
CO 0.019 0.00068 2 * 10-6
C2H4O 0 0 0
Material balance on knockout drum4286250248285 10560 kg/hr08 kg/hr00 10560 kg/hr08 kg/hr
3714751418590 10608 kg/hr08 kg/hr00 10608 kg/hr08 kg/hr
Figure SEQ Figure * ARABIC 6. Knockout drum
Its main function is to remove of liquid from gas so that it does not goes to compressor.

Total Flow rate feed= 10608 kg/hrMolar flow rate=275 kmol/hrEfficiency= 96%
Moisture removed= 18%
Moisture removed= 275*.18*0.96 = 475 kg/hrFlow rate of product = 10608 – 47.5 = 10560.5 kg/hrMolar Flow rate= 241 kmol/hrInput Stream
Table SEQ Table * ARABIC 6. Material balance on knockout drum
Component Kg/hrKmol/hrMol. Frac.

CO2 10236.7 232.65 0.965
H2O 105 5.83 0.0099
C6H6 0.000106 1.36*10^-6 1 * 10-8
H2 159.12 79.56 0.015
Ar19.94 0.498 0.00188
CH4O 0.838 0.026 7.9 * 10-5
N2 111.3 3.97 1.05 * 10-2
CO 0.525 0.187 4.951 * 10-5
C2H4O 0.519 0.011 4.9 * 10-5
OUTPUT STREAM
Component Kg/hrKmol/hrMol. Frac.

CO2 10190.8 231.61 0.965
H2O 104.5 5.80 0.0099
C6H6 0.000105 1.35*10^-6 1 * 10-8
H2 158.40 79.2 0.015
Ar19.85 0.496 0.00188
CH4O 0.834 0.026 7.9 * 10-5
N2 110.88 3.96 1.05 * 10-2
CO 0.522 0.018 4.951 * 10-5
C2H4O 0.517 0.011 4.9 * 10-5
Total Material in = 10608 kg/hrTotal Material Out = 10560.5 kg/hr
Material Balance on Scrubber45910508890 9621 kg/hr08 kg/hr00 9621 kg/hr08 kg/hr45053252332990 136.8 kg/hr08 kg/hr00 136.8 kg/hr08 kg/hr1619251237615 9758 kg/hr08 kg/hr00 9758 kg/hr08 kg/hr
Figure SEQ Figure * ARABIC 7. Scrubber
It uses the technique of scrubbing which is a separation technique. With the help of potable water the water soluble impurities are removed in the scrubber. The principle applied in scrubber is absorption as water absorbs water soluble impurities.

Total Flow rate feed= 9758.02 kg/hrMolar flow rate=241 kmol/hrEfficiency= 90%
Impurity removed= 0.06%
Impurity removed= 9758.02*0.006*0.9 = 52.7 kg/hrWater removed = 9758.02*0.00958*0.9 = 84.13
Total removed = 52.7 + 84.13 = 136.83 kg/hrFlow rate of product = 9758.02-136.8 = 9621.19 kg/hrMolar Flow rate= 223 kmol/hrInput Stream
Table SEQ Table * ARABIC 7. Material Balance on Scrubber
Component Kg/hrKmol/hrMol. Frac.

CO2 9454.54 214.87 0.9689
H2O 20.68 1.149 0.00212
C6H6 0 0 0
H2 157.1 78.55 1.61 * 10-2
Ar18.34 0.458 1.88 * 10-3
CH4O 0 0 0
N2 105.28 3.76 1.079 * 10-2
CO 0.487 0.017 5 * 10-5
C2H4O 0 0 0
Output Stream
Component Kg/hrKmol/hrMol. Frac.

CO2 9321 211.86 0.9689
H2O 20.20 1.122 0.00212
C6H6 0 0 0
H2 154.9 77.45 1.61 * 10-2
Ar18.08 0.4521 1.88 * 10-3
CH4O 0 0 0
N2 103.81 3.70 1.079 * 10-2
CO 0.481 0.0171 5 * 10-5
C2H4O 0 0 0
Total Material In = 9758.02kg/hrTotal Material Out = 9621.19 kg/hrENERGY BALANCE
Energy Balance on LP Cooler
Figure SEQ Figure * ARABIC 8. LP Cooler
Inlet Temperature = T1 = 140 °F
Outlet Temperature = T2 = 45 °F
Mean Tempearture = T = 92.3 oFSpecific heat of CO2 at (92.3 oF) = 0.221 Btu/lb.oF
Heat Removed from carbon dioxide
Q = mCp?T
= 24000*0.22*95
Q = 503880 Btu/hr
Heat Removed By Ammonia
Q=m(Cp?T+?)
503880=m((1.1*1.2)+540)
m= 931 lb/hr
Energy Balance On Intercooler
Figure SEQ Figure * ARABIC 9. Intercooler
Inlet Temperature = T1 = 173 °F
Outlet Temperature = T2 = 110 °F
Mean Temperature = T = 141.5 oFSpecific heat of CO2 at (141.5 F) = 0.221 Btu/lb.oF
Heat Removed from carbon dioxide
Q = mCp?T
= 21415×0.22×63
Q = 298168 Btu/hr
Heat Removed By water
Q=m(Cp?T)
298168=m(1×10)
m= 29816 lb/hr
Energy Balance On HP Cooler
Figure SEQ Figure * ARABIC 10. HP cooler

Inlet Temperature = T1 = 85 °F
Outlet Temperature = T2 = 45 °F
Mean Temperature = T = 65 oFSpecific heat of CO2 at (65 °F) = 0.236 Btu/lb.F
Heat Removed from carbon dioxide
Q = mCp?T
= 21100×0.236×40
Q = 199184 Btu/hr
Heat Removed By Ammonia
Q=m(Cp?T+?)
199184=m((1.1×1.2)+540)
m= 368 lb/hr
Energy Balance On Condenser
Figure SEQ Figure * ARABIC 11. Condenser
Inlet Temperature = T1 = 60 °F
Outlet Temperature = T2 = -18 °F
Mean Temperature = T = 21 oFSpecific heat of CO2 at (21 °F) = 0.289 Btu/lb.F
Heat Removed from Carbon dioxide
Q = mCp?T
= 21080×0.289×68
Q = 475185 Btu/hr
Heat Removed By Ammonia
475185 =mx589
m = 807 lb/hr

center22860Chapter 4
00Chapter 4

center104140Equipment Design
00Equipment Design

Equipment Design
Heat Exchanger
Introduction
A heat exchanger is a device in which two fluids flow against the opposite sides of a solid boundary wail which separates them while permitting heat to pass from the hot to the cold fluid. Among the various types of heat exchanges the shell and tube type is the most widely used in oil refineries and chemical plants. It consists of a number of tubes enclosed in an outer circular shell one fluid flows inside the tubes and the other fluid flows in the shell side.1314
Selection of heat exchanger
The selection process normally includes;
Thermal and hydraulic requirements
Material Compatibility
Operational Maintenance
Environmental, health and safety considerations and regulations
Availability
Cost1314
Construction
In heat exchanger design it is desirable to place the maximum number of tubes in the enclosing shell. Basically, a shell and tube heat exchanger consists of
A tube bundle which is circular in cross section and contains many closely spaced tubes
A hollow shell, which encloses the tube bundle
Baffles equally spaced among the tube length which have segmental cut outs at the opposite sides of successive baffles to cause flow back and forth across the tube bundle.
The simplest type of construction for a shell and tube heat exchanger is known as the fixed tube sheet type. In this type of unit the distance between the tube bundle and the inside circumference of the shell is at a minimum. The construction is simple, because the tube bundle is welded to the shell.

Construction features which provide for expansion and cleaning outside the tubes are incorporated in the floating head, removable tube bundle type heat exchanger. This type is standard lube oil refinery use. Oil, flowing through the shell of this exchanger enters the shell inlet nozzle and, after being directed back and forth across the tube bundle by means of segmental baffles leaves through the shell outlet.
Cooling water enters the exchanger through the channel inlet and flows through the tubes in the lower half to the floating head cover. Where, after reversing direction, it flows through the tubes in the upper half into the channel and leaves through the channel outlet. 1314

Figure SEQ Figure * ARABIC 12. (a) Shell and Tube Exchanger (BEM) with shell pass and one tube pass. (b) shell and tube exchanger(BEU) with one shell pass and two tube pass.

Heat Exchanger Design
Properties of Carbon Dioxide
Properties Inlet Outlet Units
Temp, T 140 45 F
Sp Heat, Cp0.22 Btu/lb.FThermal Conductivity, k 0.0101 Btu/hr.ft.FViscosity, ? 0.015 cPMass flow, W 24200 Lb/hrProperties of Ammonia
Properties Inlet Outlet Units
Temperature, T 32 35 F
Sp Heat, Cp1.1 Btu/lb.FThermal Conductivity, K 0.29 Btu/hr.ft.FViscosity 0.19 cPHeat Balance
Hot
Q = WC ?T
= (24200) (0.22)(140-45)
= 505780 Btu /hr
Cold
Q = w(c?T+?)
505780 = (w){(1.1*3)+(540)}
w = 931 lb/hrCaloric Temperature
Average Temperature may be used
Tc=92.5 F
Tc =33.5F
4. Assuming UD = 12 Btu/hr.ft2.F
A = Q /UD?T
= 505780/(44*12) = 958 ft2
Using 1-1 exchanger
Tube length L= 16ft Tube area per length, a” = 0.1963 ft2 /ft
Area = LNa”
N =Area/L.a”
=958/(16*0.1963)
N =305
Tube data;
OD , BWG , Pitch = ¾”,18,15/16″ triangular
N = 301

Shell ID =19 ¼”
Corrected Area
A=LNa”
=16*301*0.1963
A = 945.4 ft2
Corrected UD
UD=Q/A?T
Table SEQ Table * ARABIC 8.Heat Exchanger Design
Flow Area of Shell
as = (ID*C*B)
144*PT
= (19.25*0.1875*12)/(144*0.9375)
= 0.321ft2
Flow Area of Tube
8210552794000
aT =
at” = 0.334in2
aT = (301*0.334)/(144*1)
= 0.698 ft2
Mass Velocity
GS = W/as
= 934/0.321
= 2913 lb/hrft2
2. Mass Velocity
Gs = W/as

= 24200/0.698

= 35000 lb/hrft2
Reynolds Number
11303009906000
NRe =

De = 0.55/12

= 0.0458 ft
NRe. = (0.0458*2913)/(0.19*2.42)
=285
1048385168910003. Reynolds Number
NRe =
DT = 0.652/12

= 0.0543ft

NRe = (35000*0.0543)/(0.015*2.42)
= 52000
JH
= 8
4. JH
=155
4572008001000

= (1.1*0.19*2.42/0.29)1/3

= 1.2
16065580010005.
= (0.22*0.015*2.42/0.0101)1/3
=0.9247
= 505780/(945.4*44)
UD=12.16 Btu/hr.ft2.F
Assume 1-1 exchanger Flow area/tube = 0.334 in2
Baffles space = 12″
C’ = Pitch-OD of tube
= 0.9375-0.75
= 0.1875″
10.
11938001524000
ho =JH * k/D
4064008890000
= 1.0
ho = 8 *0.29*1.2/0.0458*1
= 61 Btu/hr.ft. oF

77787517145000 10.
hi =JH *

hi = 155*0.0101*0.9247/0.0543 *1
76390516383000 = 26.66 Btu/hr.ft2 0F
hio = hi
= 26.66 *0.652/0.75
= = 23.2 Btu/hr.ft2 0F
615950901700011.
UC =
= (61*23.2)/(61+23.2)
= 16.8 Btu / hr.ft2 0F
806450622300012.

Rd =
=(16.8-12.14)/(16.8*12.14)
=0.002 hr.ft2.F/Btu

Calculation of Pressure Drop
Shell Side Tube Side

(N+1) = 12(L/B)

= 12(16/12)

=16
f = 0.0042

Gs=2913

Ds=1.6ft

Deq=0.0458ft

S = 0.61

?Ps= 2.15 Psi
?Pt=(f*Gt2*L*n)/(5.22*1010*D*s*?t)
f = 0.00015
Gt =3.5*104
L = 16ft
n =1
D=0.0543ft
S =0.002

= 0.59 psi
4616456604000
?Pr =
=0 psi

= 0.59 psi
Compressor Design
Screw Compressor
The single screw oil lubricated compressor is a rotary, positive displacement compressor which incorporates a main screw and two gate rotors.
Range 100psig – 350psig
Easy capacity control
Less moving parts
Less maintenance cost

Figure SEQ Figure * ARABIC 13. Screw compressor

Compressor Horse Power Calculations:
Total Flow = 9758 Kg/hr
= 21513 Lb/hrInlet Pressure P1 = 84 Psia

Outlet Pressure P2 = 279Psia
Density of Gas = ?G = PM/RT
?G = (84*44)/(82.06*316.3) = 0.6 Lb/ft3
Volumetric Flow rate = 21513/ 0.6×60 = 597.5 ft3/min
From figure 1 Selection of Compressor
“As our desired compressor is centrifugal compressor”
Number of Stages;
If P2/P1 ; 5, then Number of stages = 1
So we have
P2/P1 = 280/84 = 3.33

So we have Number of Stages = NS = 1
Power Calculation = (3.03 x 10-5 x K x NS/(K-1)) x P1 x qfm1 x { (P2/P1)(K-1)/KNs – 1}
Putting in values
K = Cp/Cv = 1.2 (From Rules of Thumb Of Chemical Engineers)
Power = 278.9 hp
Assume
Efficiency = 70%
Actual Horse Power = 278.9/0.70
= 398.43 HP
Pumps
Introduction:
Pumps are used to transfer liquids from one location to other. The pump accomplishes this transfer by increasing the pressure of the fluid and, thereby, supplying the driving force necessary for flow. Power must be delivered to the pump from an outside source. The, electrical or steam energy may be transformed into mechanical energy which is used to drive the pump. Part of this mechanical energy is added to the fluid as work, and the rest is lost as friction due to inefficiency of the pump and drive.
Many different factors can influence the final choice of a pump for a particular operation. The following list indicates the factors that govern pump selections:
The amount of fluid that must be pumped, this factor determines the size of pump (or pumps) necessary.
The properties of the fluid, density and the viscosity of the fluid influence the power requirement for a given set of operating conditions; corrosive properties of the fluid determine the acceptable materials of construction. If solid particles are suspended in the fluid, this factor dictates the amount of clearance necessary and may eliminate the possibility of using certain types of pumps.
The increase in pressure of the fluid due to the work input of the pumps. The head change across the pump is influenced by the inlet and downstream-reservoir pressure, the change in vertical height of the delivery time, and frictional effects. This factor is a major item in determining the power requirements.

Type of flow distribution: If non-pulsating flow is required certain types of pumps, such as simplex reciprocating pumps may be unsatisfactory. Similarly, if operation is intermittent, a self-priming pump may be desirable, and corrosion difficulties may be increased.
Type of power supply: Rotary positive displacement pumps and centrifugal pumps are readily adaptable for use with electric-motor or internal combustion-engine drives; reciprocating pumps can be used with steam or gas drives.

Cost and mechanical efficiency of the pump. 1314
Centrifugal Pump
The centrifugal pump is by far the most widely used type in the chemical and petroleum industries. It will pump liquids of very wide range of properties and suspensions with a high solids content including. e.g. cement slurries, and may be constructed frorn a very wide range of corrosion resistant materials. The whole pump casing may be constructed from plastics such as polypropylene or it may be fitted with a corrosion resistant lining. Because it operates at high speed, it may be directly coupled to an electric motor and it will give a high flow rate for its size.
In this type of pump the fluid is fed to the centre of rotating impeller and is thrown outward by centrifugal action. It of the high speed of rotation the liquid acquires a high energy and the pressure difference between the suction and delivery sides rise from the conversion of kinetic energy into pressure energy.
The impeller consists of a series of curved vanes so shaped the flow within the pump is as smooth as possible. The greater number of vanes on the impeller, the greater is the control over direction of motion of the liquid and hence the smaller are the losses due to turbulence and circulation between the vanes. In the open impeller the vanes are fixed to a central hub, whereas in the type the vanes are held between two supported plates and leakage across the impeller is reduced. As will be seen later, the angel of the tips of the blades vary largely determines the operating characteristics of the pump.
The liquid enters the casing of the pump, normally in an axial direction, and is picked up by the vanes of the impeller. In the simple type of a centrifugal pump, the liquid discharges into a volute, a chamber of gradually increasing cross-section with a tangential outlet. In the turbine pump, the Iiquid flows from the moving vanes of the impeller through a series of fixed vanes forming diffusion ring. This gives a more gradual change in direction to the fluid and more efficient conversion of kinetic energy into pressure energy than is obtained with the volute type. 1314
Cavitation
In designing any installation in which a centrifugal pump is used, careful attention must be paid to check the minimum pressure, which will arise at any point. If this pressure is less than the vapour pressure at the pumping temperature, vaporization will occur and the pump may not be capable of developing the required suction head. Moreover, if the liquid contains gases, these may come out of solution giving rise to pockets of gas. This phenomenon is known as cavitation and may result in mechanical damage to the pump as the bubbles collapse. The tendency for cavitation to occur is accentuated by any sudden changes in the magnitude or direction of the velocity of the liquid in the pump. A marked increase in noise and vibration as the vapour bubbles collapse and also a loss of head accompany the onset of cavitation. 1314
Suction Head
Pumps may be arranged so that the inlet is under a suction head or the pump may be fed from a tank. These two systems alter the duty point curves. In developing such curves the normal range of liquid velocities is L5 to 3 m/s, but lower values are used for pump suction lines.
For any pump, the manufacturers specify the minimum value of the suction pressure known as Net Positive Suction Head (NPSH) which must exist at the suction point of the pump. The NPSH is the amount by which the pressure at the suction point of the pump, expressed as a head of the liquid to be pumped, must exceed the vapour pressure of the liquid. 1314
Suction Lift
If the pump is fed liquid from a tank placed below the centre line of the pump then the height through which the liquid is to be lifted before it reached pump is called suction lift. 1314
The advantages and disadvantages of the centrifugal pump
Advantages
The main advantages are:
It is simple in construction and can, therefore, be made in a wide range of materials.
There is a complete absence of valves.
It operates at high speed (up to 67 Hz) and, therefore, can be coupled directly to an electric motor. In general, the higher the speed the small the pump and motor for a given duty.
It gives a steady delivery.
Maintenance costs are lower than other types of pump.

No damage is done to the pump if the delivery line is blocked provided it is in this condition for a prolonged period.
It is much smaller than other pumps of equal capacity. It can, therefore, be made into a seared unit with the driving motor and immersed in the suction tank.
Liquids containing high proportions of suspended solids are readily handled. 1314
Disadvantages
The main disadvantages are:
The single-stage pump will not develop a high pressure. Multistage pumps will, develop greater heads but they are very much expensive and cannot readily be made in corrosion-resistant material because of their greater complexity. It is generally better to use very high speeds in order to reduce the number of stages required.
It operates at a high efficiency over only a limited range of conditions: this applies especially to turbine pumps.
It is not usually self priming.
If a non-return valve is not incorporated in delivery or suction line, the liquid will run back into the as soon as the pump stops.
Very viscous liquids cannot be handled efficiently. 1314

High Pressure Vessel Design
(SEPARATOR)
(Procedure from Rules of Thumb for Chemical Engineer)
Calculate the Separation Factor = (WL/WV) x (?v/?L) 0.5
WL = Liquid Flow Rate = 7784 kg/hr
= 4.76 lb/sec
WV = Vapour Flow Rate = 1410 kg/hr
= 0.86 lb/sec
?v = Density of Vapor at S.L.
Molecular Weight = 18
Temperature = -27.8?C
Pressure = 271.9 Psia
?v = 18 x 492 x 257.2/ 359 x 442×14.7
= 0.976 lb/ft3
Liquid Density = 2.4lb/ft3
Separation Factor = (4.76/0.86) x (0.976/2.4)0.5 = 3.53
-20564431870300

From Graph Value of KV against (WL/WV) x (?V/?L)0.5
KV = 0.5
Kh = 1.25 KV
183515022733000 Kh = 0.625
Vapour Velocity µvapour max =
=
µvap max = 0.755ft/sec
Liquid Flow Rate QL = 4.76 lb/sec x ft3/2.4 lb
=1.98ft3/sec
Vapour Flow Rate QV = 0.86lb/sec x ft3/0.976 lb
= 0.88 ft3/sec
Let Design Time to fill = 154 sec.
Required Vessel Surge Volume = QL x Design Time
= 0.88 x 154
Volume of Vessel = 135 ft3
Calculate required vapour flow area:
(AV)min = QV/ µvap max
= 0.88 / 0.755 = 1.16 ft2
When vessel full of liquid volume

(A total) min = 1.16/0.2 = 5.8 ft2

Dmin = 4 x (Atotal)min / ? 0.5 = 2.7 ft
L = Full Liq Volume /( ? /4) D2
= 135/ (?/4) x (2.7)2
= 23 ft
Vessel Thickness

P = Pressure, psig = 300 psi
r = Radius = (1.35 x 12)”=16.2″
S = Allowable stress, psi = 13700 psi
E = Weld efficiency, fraction = 0.85
C = Corrosion allowance, in. = 0.08″

T = (P x r) / (SE – 0.6P) + C
= (300 x 1.35 x 12) / (13700 x 0.85) – (0.6 x 300)+.08
= 0.5″
Stripper Design
Average Temperature = -28.9 `C
Average Pressure = 257.3 Psi
Molecular Weight = 44 kg/kg-mole
?G = (44x 257.3)/244.1×82.06
= 2.4Lb/ft3
?L = 3Lb/ft3
Gm = Kv (?G(?L- ?G))0.5
For 18″ tray spacing
KV = 0.24
Gm = 0.48 Lb/ft2s = 1728 Lb/ft2hr
Area = Mass Flow rate / Gm
= 3.14 ft2
Diameter = 2 ft
Assume
Number of Trays = 10
Height of Column = Tray Spacing x Number of trays
= (18/12) x 10
= 15 ft
Shell Thickness
Pressure = 257.3 psi
Radius = D /2 = 12″
Material of construction = C.S
Tensile Strength = 13700 Psi
EJ = 0.85
Corrosion Allowance = CC = 0.125″

Thickness = P x R / (S.EJ – 0.6P) + CC
Thickness = 0.5″
center2616897Instrumentation
00Instrumentation
center1723226Chapter 5
00Chapter 5

Instrumentation And Process Control
Measurement is a fundamental requisite to process control. Either the control can be affected automatically, semi-automatically or manually. The quality of control obtainable also bears a relationship to the accuracy, re-product ability and reliability of the measurement methods, which are employed. Therefore, selection of the most effective means of measurements is an important first step in the design and formulation of any process control system.151617
Process Control
Chemical Plant is a game plan of handling units (reactors, refining sections(distillation), Absorber, Heat Exchangers, evaporators, tanks. and so forth.), incorporated with each other in an orderly and reasonable way. The plant’ general goal is to change over certain crude materials (Input feedstock) into wanted items utilizing accessible Sources of vitality, in best way.

Amid its operation, Chemical plant necessarily fulfill a few require, forced by designer and the general specialized, financial, and social conditions within the sight of over-changing (disturbances) outer impacts.

As rivalry winds, up noticeably stiffer in chemical commercial centre and process-system turn out to be more muddled to work, it is favorable to make utilization of some type of programmed control. Programmed control of a process-system offers many favorable circumstances, including
Filling Environmental Constraints
Improved Process Safety
Compliance to Severer Quality Specifications of Product
More Effective Utilization of Energy and Raw-Materials
Improved Profitability
Considering every one of the advantages that can be acknowledged through process control, it is definitely justified even despite the time and exertion required to get comfortable with the ideas and practices utilized as a part of the field. 151617
Control Systems
Control system, utilized to keep up prepare conditions at their coveted esteems by controlling certain procedure factors to modify the variables. A typical case of a control system in regular day to day existence is the journey control on a car. The motivation behind a journey control is to keep up the speed of the vehicle (controlled variable) at the coveted esteem (set point) in spite of varieties in territory, slopes, and so forth (aggravations) by changing the throttle, or the fuel stream to the motor (controlled variable). Another regular illustration is the home heated water storage. The control system, on the heated water tank endeavors to keep up the temperature in the tank at the coveted an incentive by controlling the fuel stream to the burner (for a gas warmer) or the electrical contribution to the radiator despite aggravations, for example, the shifting interest on the warmer at a young hour in the morning, as it is called upon to give water to the day by day showers. A third illustration is the home-thermostat. 151617
Objectives
The primary objectives of the designer then specifying instrumentation and control scheme are
Safe Plant Operations
To keep the process variables within known safe operating limits.

To detect dangerous situations as they develop and to provide alarms and automatic shutdown systems
Production Rate
To achieve the desired product output
Product Quality
To maintain the product composition with the specified quality standard
Cost
To operate at the lowest production cost
Design Element of Control System
Define the Control Objective
Select the Measurement
Select the Manipulated Variable
Select the Control Configuration
Define the Controller 151617
Hardware Elements of a Control System151617
In every control configuration, we can distinguish the following hardware elements;
The Chemical Process
It represents the material equipment together with physical or chemical operation that occur there.
The Measuring Sensory Instruments
Such Instrument are used to measure the disturbances, the controlled output variables, or secondary output variables, and are the main of information what is going on in the process.

Transducers
Numerous measurements can’t be utilized for control until the point when they are changed over to physical amounts, (for example, pneumatic signal or current or electric voltage, i.e., compressed liquid or air) which can be transmitted effectively. Transducers are utilized for that reason. For instance, strain instruments are metallic channels whose electric resistance changes when they are subjected to mechanical-strain. In this manner, they can be utilized to change over a pneumatic-signal to an electric one.

Transmission Lines
These are utilized to convey the quantity signal from measuring gadget to the controller. Previously, transmission-lines were pneumatic (compressed liquids or air) yet with appearance of electronic simple controllers and particularly the extending utilization of computerized PCs for control, electric signals conveyed through transmission lines. Ordinarily, measurement-signal originating from a measuring gadget is exceptionally frail and can’t be transmitted over a long separation. In such cases the transmission lines are furnished with enhancers which raise the level of the flag. For instance, the yield of a thermocouple is of the request of a couple of millivolts. Before it is transmitted to the controller, it is increased to the level of a couple of volts.
Controller
This is hardware component that has “insight.” It gets the data from the measuring gadgets and chooses what move ought to be made. The more established controllers were of restricted insight, could perform exceptionally basic operations, and could execute Simple control laws. Today, with expanding utilization of advanced Computers as controllers, the accessible machine knowledge has extended immensely, and extremely confounded control laws can be actualized.

Function of the controller is to look at the procedure motion from the transmitter with the set point flag and to convey a proper flag to the control valve.

Final Control Elements
System which adjusts the estimation of the controlled variable because of the yield motion from and programmed controller. In a greater part of System, the last control component is and programmed control valve which throttles the stream of a manipulative variable.

Recorder
Recorder is installed in order to record the system behavior and help in future.

Selection of Controller Type
Which one of the three famous Feedback-Controllers ought to be utilized to control a given procedure? The inquiry can be replied in an extremely orderly way as takes after:
Characterize a proper execution paradigm (e.g., ITAE, ISE or IAE)
Register value of execution paradigm utilizing a P, or PI, or PID controller with best settings for the balanced parameters KC, ?D and ?I.
Select that controller which gives the “best” esteem for the execution basis
This technique, albeit numerically thorough, has a few genuine reasonable disadvantages:
It is extremely dreary
It depends on models (exchange capacities) for process-system. Sensor and last control component which may not be known precisely
It fuses certain ambiguities as to which is the most suitable basis and what input changes to consider
Luckily, we can choose the most proper sort of input controller utilizing just broad subjective contemplations. There we had inspected the impact of the corresponding, fundamental, and subsidiary control modes on the reaction or a process-system. 151617
Proportional Control
Accelerates reply of controlled-process
Generates offset for all process aside from those with terms 1/s (integrators) in their transfer-function, for example, the fluid level in a tank or the gas weight in a vessel.

Integral Control
Offset Removal
Removal of offset generally comes to the detriment of higher greatest deviations.
Produces languid, long swaying reactions
On the off chance that we increment the pickup KC to deliver quicker reaction, system turns out to be more oscillatory and might be directed to flimsiness.

Derivative Control
Forestalls future deviation and presents appropriate response
Presents a stabilizing result on closed-loop action of process-system151617
General Control System
Following are the important general control system:
Open and close loop system
Feedback control system
Forward control system
Cascade control system
Open Loop System
Control system in which information about the controlled variables is not used to adjust any of the system inputs to compensate for variation in the process variables. These terms are used to indicate uncontrolled process dynamic.
Closed Loop System
The control system in which the controlled variable is measured and the result of this measurement is used to manipulate one of the process variables.
Feedback Control System
In a closed loop control system information about controlled variable is fed back as the basis for the control of the process variable. For automatic control a measuring device is used. It generates a signal, which is fed to a controller which compares it with a preset desired value or set point, if a difference exists the controller sends a signal to final control element.
Forward Control System
Process disturbances are measured and compensate without waiting for a change in a controlled variable to indicate a disturbance has occurred. It is also useful when a final controlled variable cannot be measured.
Cascade Control System
It is often used for minimizing disturbances entering in a slow process. It also speeds up the response of the control system by reducing time constant relating the manipulated variable process output. Instead of adjusting the final control element such as control valve the output of primarily controller is made the set point of secondary controller. 151617

Figure SEQ Figure * ARABIC 14. Instrumentation diagram of CO2 Plant
center206416Chapter 6
00Chapter 6

center41910Cost Estimation
00Cost Estimation

Cost Estimation
Introduction:
An acceptable plant design must present a process that is capable of operating under conditions, which will yield a profit. Since net profit equals total income minus all expenses, it is essential that the chemical engineer be aware of the many different types of costs involved in the manufacturing processes.
A capital investment is required for any industrial process, and project. The total capital investment for any process consists of the plant plus working capital, which must be available to pay salaries, keep raw materials and products on hand.18
Factors Affecting Investment & Production Costs:
When a chemical engineer determines costs for any type of commercial process, these costs should be of sufficient accuracy to provide reliable decisions. To accomplish this, the engineer must a complete understanding of the factors that can affect costs.
Some important factors are:
Sources of equipment
Price fluctuations
Company policies
Operating time and rate of production
Government policies 18
Types Of Capital Cost Estimates:
An estimate of the capital Investment for a process may vary from a pre designed estimate based on little information except the proposed project to a detailed estimate prepared from complete drawings and specifications.

1. Order of magnitude estimate (or ratio estimate) based on similar previous cost data, probable accuracy estimate over 30 percent.
2. Study estimate (or factored estimate) based on knowledge of major items of equipment: probable accuracy of estimate up to +30 percent.

3. Preliminary estimate (or budget authorization estimate, scope estimate) based on sufficient data to permit the estimate to be budgeted; probable accuracy of estimate within +20 percent.

4. Definitive estimate (or project control estimate) based on complete data but before completion of drawings and specifications: probable accuracy of estimate within +10 percent.
5. Detailed estimate (or contractor’s estimate) based on complete engineering drawings, specifications, and site surveys; probable accuracy of estimate within +5 percent.
Pre-design cost estimates requires less detail than firm estimates such as the definitive or detailed estimate. However, the pre-design estimated are extremely important for determining if a proposed project should be given further consideration and to compare alternative designs. 18
Cost Indexes:
Most cost data which are available for immediate use in preliminary or pre-design estimate are based on condition at sometime in the past.
A cost index is merely as index value for a given point in time showing the cost at that time relative to a certain base time. If the cost at sometime in the past is known the equivalent cost at the present time can be determined by multiplying the original cost by the ratio of percent index value to the index value applicable when the original cost was obtained.
Many different types of cost indexes are published regularly. The most common of these indexes are:
Marshal ; Swift all-industry and Process Industry equipment Indexes.
Engineering News-Record Construction Index
Nelson — Farrar Refinery Construction Index.
Chemical Engineering Plant Cost Index 18
The Marshall and Swift (formerly known as Marshall and Stevens) index is mostly used.

Present cost = Original cost x Index value at Present time Index value at time original cost was obtained
Index value at time original cost was obtained = 1449 (Marshall Swift Index)
Index value at present time(Latest year 2017) = 1593.7
Cost of Equipment
Heat Exchanger
Original Cost = 5.9 Million Rs.
Cost of heat exchanger in 2018 = Rs.5.9 Million(1593.7/1449)
Cost in 2018 = 6.49 Million Rs.

Number of heat exchanger = 5
Cost of heat exchanger = Rs. 6.49 Million x 5
= 32.5 Million Rs.

Pumps
Original Cost = 0.5 Million Rs.
Cost in 2018 = Rs. 0.5 Million x (1593.7/1449)
Cost in 2018 = 0.55 Million Rs.

No of pumps = 3
Cost of pumps = 0.55 x 3
= 1.65 Million Rs.

Compressor
Original Cost = 2.32 Million Rs.

Cost in 2012 = Rs 2.32 Million x (1593.7/1449)
Cost of one Compressor = 2.55 Million RsNo of compressor = 3
Cost of compressor = 2.55 x 3
Cost of compressor = 7.65 Million Rs.

High Pressure Vessel
Capacity = 22000 gal
Original Cost = 9.49 Million Rs.

Cost in 2018 = Rs 9.49 Million x (1593.7/1449)
Cost in 2018 = 10.4 Million Rs.

No of vessels = 4
Cost of Pressure Vessel = 10.4 x 4
= 41.6 Million Rs.

Stripper
I.D = 24 inches
Number of plates = 10
Original Cost per plate = 1.11 Million Rs.

Cost in 2018 = Rs. 1.11 Million x (1593.7/1449)
Cost in 2018 = 1.22 Million Rs.

Cost of Stripper = 1.22 x10
= 12.2 Million Rs.

Dryer
Original Cost = 9.37 Million Rs.

Cost in 2018 = Rs. 9.37 Million x (1593.7/1449)
= 10.30 Million Rs.

Condenser
Original Cost = 2.66 Million Rs.

Cost in 2018 = Rs 2.66 Million x (1593.7/1449)
= 2.92 Million Rs.

Scrubber
Original Cost = 5.9 Million Rs.

Cost in 2018 = Rs. 5.9 Million x (1593.7/1449)
= 6.48 Million RsTotal Equipment Cost = 115.3 Million Rs.

Estimating Capital Investment (C.I)
(Table 17, Chapter 6, Timmerhaus)
Table SEQ Table * ARABIC 9. Direct cost estimation
Co2 Liquefaction Unit Percentage Of Equipment Cost Direct Cost Rs

(Million)
Purchased Equipment Cost 100 115.3
Equipment Installation Cost 40 46.12
Piping(installed) 31 35.74
Electrical 10 11.53
Instrumentation and control 28 32.28
Building (including services) 29 33.43 Yard improvement 10 11.53 Services Facilities (installed) 70 80.71
TOTAL DIRECT COST 366.64
INDIRECT COSTS (IDC)
Table SEQ Table * ARABIC 10. Indirect cost estimation
Engineering and Supervision 33 38.049
Construction Expenses 34 39.2
Contractor’s fee 5%(D.C) 18.332
Total IDC 95.58
Contingency 30%(FCI)
FIXED CAPITAL INVESTMENT
FCI = D.C + IDC + contingency
FCI = 366.64 + 95.58 +0.3(FCI)
FCI = 660.31 Million Rs.

Total Capital Investment
TCI = FCI + Working Capital
As working capital = 15% of TCI
So, TCI = FCI + 0.15(TCI)
T CI = 660.31 + 0.15(TCI)
TCI = 777 Million Rs.
Working Capital = 0.15 x TCI
Working capital = 116.5 Million Rs.

Depreciation
V= fixed capital cost = 660.31 Million Rs.

Vs= 5% of FCI= 33 Million Rs.

n= 20
Depreciation(d)= V-Vs/n
= (660.31-33)/20
= Rs 31.36 Million /year
Payback Period
Liquefied CO2 Price = Rs. 30 / Kg
Production = 8333 Kg / hr
Total Annual Income = Capacity x unit selling price x 300 days
= 8333 x 30 x 300 x 24
= 1.8 billion Rs.

Operating Cost = 0.25 x FCI
= 0.25 x 660.31 Million Rs.

= 165 Million Rs.

Profit after Depreciation = 1.8 Billion – 165 million – 33 million
= 1.6 Billion Rs. / Year
Annual Income Tax = Rs (0.4 x 1.6 Billion)/Year
= 0.64 Billion Rs.

Net Profit = Rs(1.6 – 0.64) Billion Rs.

= 0.96 Billion Rs./Year
Payback period = FCI / Annual cashflow = 660.31/960
= 7 months
center2005146Chapter 7
00Chapter 7
center2967826Environment, HAZOP Study & Site Selection
00Environment, HAZOP Study & Site Selection

HAZOP Study
Background
HAZOP think about distinguishes risks and operability issues. The idea includes exploring how the plant may stray from the outline goal. On the off chance that, during the time spent recognizing issues amid a HAZOP think about, an answer winds up plainly obvious, it is recorded as a feature of the HAZOP result; notwithstanding, mind must be taken to abstain from attempting to discover arrangements which are not all that clear, in light of the fact that the prime target for the HAZOP is issue ID. In spite of the fact that the HAZOP think about was produced to supplement encounter based practices when another outline or innovation is included, its utilization has extended to all periods of a vegetation’s. HAZOP depends on the rule that few specialists with various foundations can communicate and recognize a bigger number of issues when cooperating than when working independently and joining their outcomes. The “Guide-Word” HAZOP is the most understood of the HAZOPs; in any case, a few specializations of this essential technique have been created.19
Concept
A HAZOP survey is one of the most common and widely accepted methods of systematic qualitative hazard analysis. It is used for both new or existing facilities and can be applied to a whole plant, a production unit, or a piece of equipment It uses as its database the usual sort of plant and process information and relies on the judgment of engineering and safety experts in the areas with which they are most familiar. The end result is, therefore reliable in terms of engineering and operational expectations, but it is not quantitative and may not consider the consequences of complex sequences of human errors.

Accomplishment or disappointment of HAZOP rest on numerous aspects:
Comprehensiveness and accurateness of sketches and other facts utilized as base for study.
Technical services and visions of team.
Capacity of group to utilize the approach as a guide to their creative ability in imagining deviations, causes, and outcomes.

Capacity of the group to focus on the more genuine dangers which are recognized. 19
Process is deliberate and it is useful to characterize the terms that are utilized:
Study Nodes
Areas (on instrumentation drawings and methodology and piping) at which the procedure parameters are explored for deviations. 19
Intention
Intention characterizes how the plant is relied upon to work without deviations at the examination hubs. This can take various structures and can either be spellbinding or diagrammatic; e.g., line outlines, flowsheets, P;IDS. 19
Deviations
These are take-offs from intentions that are found by deliberately applying the guide words (e.g., “more Flow”).19
Causes
These are reasons why deviations may happen. Once a deviation has been appeared to have a dependable aim, it can be dealt with as a significant deviation. These causes can be equipment disappointments, human blunders, an unexpected process state, outside disturbances, and so forth.

Consequences
These are the aftereffects of the deviations should they happen (e.g., arrival of dangerous materials). Insignificant results, with respect to objective examine, are dropped. 19
Guide Words
These are basic words which are utilized to qualify or measure the goal keeping in mind the end goal to manage and invigorate the conceptualizing procedure thus find deviations. The guide words appeared in the accompanying table are the ones frequently utilized as a part of a HAZOP; a few associations have made this rundown particular to their operations, to manage the group all the more rapidly to the regions where they have already discovered issues. Each guide word is connected to the procedure factors at the point in the plant which is being analysed. 19
Guide Words of HAZOP
Table SEQ Table * ARABIC 11. Guide Words of HAZOP
Guide Word Meaning
NO Negation of Design Intent
More Quantitative Increase
Part of Qualitative Decrease
Less Quantitative Decrease
As Well As Qualitative Increase
Other than Complete Substitution
Reverse Logical Opposite of Intent
Guide words, pertinent to both broader parameters (e.g. respond, exchange) and to more particular parameters (e.g. temperature, pressure stream). With general parameters, important deviations are normally created for each guide word. Additionally, it is not strange to have more than one deviation from the utilization of one guide word. For instance, “more response” could mean either that a response happens at a speedier rate, or that a more prominent amount of item comes about.
With the particular parameters, some alteration of the guide words might be essential. Also, it is not strange to locate that some potential deviations are killed by physical restriction. For instance, if the outline aim of a weight or temperature is being viewed as, the guide words “more” or “less” might be the main potential outcomes. 19
Guidelines for Application
Concepts introduced earlier are placed into exercise in following phases:
Outline purpose, aims and room of study
Choose team
Prepared for study
Do team assessment
Record outcomes
Follow-up to confirm, results are executed
HAZOP Team Members
In HAZOP Study the HAZOP members, together with their affiliations and positions are specified. Their duty, capabilities, and applicable experience ought to likewise be given. The director and the secretary of the gathering ought to likewise each be distinguished. The dates of the gatherings and their span ought to be given. Where a few individuals were absent at all gatherings, the degree of their support ought to be shown. Unique guests and periodic individuals ought to be recorded in a way like the proceeding with individuals, with the purposes behind their participation itemized. For instance, expert instrumentation build/advisors might be required to defeat particular outline issues. 19
HAZOP Methodology
General approach utilized ought to be quickly delineated. Any progressions to acknowledged standard philosophy utilized for a HAZOP ought to be clarified. 19
Plant Overview
In HAZOP Study, it ought to be delineated what general conditions and circumstances prone to bring about a possibly unsafe result were considered in HAZOP (following line by line examination) for the general P;ID or area including diagram issues, for example,
Start-Up Measures
Emergency Shutdown Measures
Pre-Commissioning Operator Drill
Instrumentation Trip and Alarms Testing
Failure of Services
Plant Safety Systems
Breakdowns
Noise
Effluent (gas, liquid, solid) 19
Main Findings Analysis
A sign of the criteria used to decide if activity was being taken in regards to the result of a deviation is required. The aftereffects of the HAZOP, giving deviations, outcomes and activities required, ought to be given. Those occasions on which the choice of no activity was made ought to likewise be recorded, alongside the occasions for which result or hazard examination was viewed as fundamental. The choices made after such further investigations ought to likewise be given. 19
Activities Ascending from HAZOP
This segment ought to highpoint those activities which are possibly dangerous to plant workers, environment or public or have probable to risk operability of plant. Also, comprised ought to be a indistinct declaration of assurance to alter operational actions or design in agreement with identified compulsory activities and a schedule for application. Explanation as, why not one act was selected for any activities recognized, ought also to be complete. 19
Material Safety Data Sheet19
Identification
Product Name: Carbon Dioxide
Chemical Formula: CO2
Company Indentification: Pakarab Liquid CO2
Composition/Information of Ingredients
Ingredient Name: Carbon Dioxide
Hazards Identification
Refrigerated liquefied gas.

Contact with product may cause cold burns or frostbite and in high concentrations may cause asphyxiation.

Exposure Limits
ACGIH TLV-TWA 5,000 ppm
ACGIH TLV-STE 30,000 ppm
IDLH: 50,000 ppm
OSHA PEL-TWA 10,000 ppm (final)
OSHA PEL-STEL 30,000 ppm (final)
OSHA PEL-TWA 5,000 ppm (Trans.)
First Aid Measures
5.1 Eyes
Never introduce ointments or oil into eyes without medical advice! In case of freezing or cryogenic “burns” caused by rapidly evaporating liquid, DO NOT WASH THE EYES WITH HOT OR EVEN WARM WATER! Remove the victim from the source of contamination. Open eyelids wide to allow liquid to evaporate ophthalmologist for treatment and follow up. If the victim cannot tolerate light, protect the eyes with a light bandage.
5.2 Skin
For dermal contact or frostbite, flush affected areas with large quantities of warm water. DO NOT USE HOT WATER OR DRY HEAT. DO NOT RUB! A physician should see the patient promptly if the cryogenic “burn” has resulted in blistering or deep tissue freezing.
5.3 Ingestion
Treat in a similar manner as skin contact. Seek medical attention as soon as possible.
5.4 Inhalation
Quick removal from the contaminated area is most important. Conscious persons should be assisted to an uncontaminated area and inhale fresh air. Unconscious persons should be moved to an uncontaminated area, and given artificial resuscitation and supplemental oxygen if they are not breathing. Further treatment should be symptomatic and supportive.

Fire Fighting Measures

Specific hazards Exposure to fire may cause containers to rupture/explode.

Combustion product Non flammable
Suitable extinguishing media All known extinguishants can be used.

Specific methods If possible, stop flow of product. Move container away or cool with water from a protected position
Special protective Equipment for fire fighters In confined space use self- contained breathing apparatus.

Accidental Release Measures
Personal precautions Evacuate area. Use protective clothing. Wear self-contained breathing apparatus when entering area unless atmosphere is proved to be safe. Ensure adequate air ventilation
Environmental precautions Try to stop release. Prevent from entering sewers basements and work pits.

References
1 www.scienceclarified.com/Ga-He/Gases-Liquefaction-Of-Co2.html2 www.encyclopedia2.thefreedictionary.com/Gas+Purification3 Harris DF. THE PIONEER IN THE HYGIENE OF VENTILATION. Lancet. 1910. doi:https://doi.org/10.1016/S0140-6736(00)52420-9.

4 Almqvist E. History of Industrial Gases, Springer; 2003.

5 Davy H. On the Application of Liquids Formed by the Condensation of Gases as Mechanical Agents. Philos Trans. 1823. doi:10.1098/rstl.1823.0020.

6 Priestley, Joseph; Hey W. Observations on Different Kinds of Air. Philos Trans. 1772. doi:10.1098/rstl.1772.0021
7 Solidification of Carbonic Acid. London Edinburgh Philos Mag. 1836. doi:10.1080/14786443608648911
8 Mitsubishi Heavy Industry M. KM-CDR Process. https://www.mhi.com/products/detail/km-cdr_process.html.

9 www.encyclopedia.com/science-and-technology/physics/liquefaction
10 http://www.uigi.com/gas_props_uses.html11 Centi G (Gabriele), Perathoner S. Green Carbon Dioxide?: Advances in CO2 Utilization.; 2014.

12 www.science.jrank.org/pages/2923/Gases-Liquefaction-Methods-liquefaction.html13 Perry RH, Green DW. Perry’s Chemical Engineers’ Handbook. Vol 8.; 2008. doi:10.1036/0071511334.

14 Rules of Thumb of Chemical Engineering by Carl Branan.
15 Singh SK. Industrial Instrumentation ; Control. 2nd Editio. Tata McGraw-Hill; 2003
16 Stephanopoulos G. Chemical Process Control-An Introduction to Theory and Practice. 1 Edition. PTR Prentice Hall; 1984
17 Coughanowr DR, Leblanc SE. Process Systems Analysis and Control.; 2008
18 Peters MS, Timmerhaus KD, West RE. Plant Design and Economics for Chemical Engineers.; 2004
19 Crawley F, Tyler B, Allford L, Gowland R. HAZOP: Guide to Best Practice.; 2015. doi:10.1016/B978-0-323-39460-4.00017-7.