PLANT DESIGN FOR MANUFACTURING ACETIC ACID

Transcription

1 A Project Report on PLANT DESIGN FOR MANUFACTURING ACETIC ACID Submitted in partial fulfillment of the requirements for the award of Degree of BACHELOR OF TECHNOLOGY IN PETROCHEMICAL ENGINEERING By T.PRUDHVI RAJ 10021A2512 Under the esteemed guidance of Mr.P.Anil kumar Lecturer DEPARTMENT OF PETROLEUM ENGINEERING & PETROCHEMICAL ENGINEERING UNIVERSITY COLLEGE OF ENGINEERING (A) KAKINADA JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY KAKINADA KAKINADA , AP ( ) 0 Page

2 CERTIFICATE This is to certify that the project report entitled PLANT DESIGN FOR MANUFACTURING ACETIC ACID is a bonafide work done by T.Prudhvi Raj (10021A2512) Submitted in partial fulfillment of the requirements for the award of Degree of Bachelor of Technology in Petro Chemical Engineering during the academic year The results of investigations enclosed in this report have been verified and found satisfactory. The results embodied in this project report have not been submitted to any other University or Institute for the award of any other degree. Head of the Department Project Guide Dr. B. Bala Krishna Head Dept. of PE & PCE UCEK(A) J.N.T. University Kakinada Mr. P.Anil Kumar Lecturer Dept. of PE & PCE UCEK(A) J.N.T. University Kakinada Project Supervisor Prof. K. V. Rao Programme Director Dept. of PE & PCE UCEK(A) J.N.T. University Kakinada

3 ACKNOWLEDGEMENTS I would like to express our sincere gratitude to the project guide, Mr. P.Anil Kumar, Lecturer, Department of Petroleum Engineering & Petrochemical Engineering, University College of Engineering (A), Jawaharlal Nehru Technological University, Kakinada, for his timely cooperation and valuable suggestions while carrying out the project. It is his kindness that made me learn more from him. I would like to express our thanks to Prof K.V.Rao, Programme Director, Department of Petroleum Engineering & Petrochemical Engineering, University College of Engineering (A), Jawaharlal Nehru Technological University, Kakinada, for their guidance given to me to finish this project successfully. I would like to acknowledge gratitude to Prof. K.Padma Raju, Principal,UCEK(A) and Dr. B.Bala Krishna, Professor and Head of the Department, Department of Petroleum Engineering & Petrochemical Engineering, University College of Engineering (A), Jawaharlal Nehru Technological University, Kakinada, for providing good environment and better infrastructural facilities. assistance. I also like to thank all my friends and well-wishers for their warm and willing T.Prudhvi Raj (10021A2512)

4 CONTENTS ABSTRACT LIST OF FIGURES LIST OF TABLES NOMENCLATURE 1. INTRODUCTION 1.1. INTRODUCTION 1.2. GLOBAL SCENARIO 1.3. INDIAN MARKET 2. PHYSICAL AND CHEMICAL PROPERTIES AND USES 2.1. PHYSICAL PROPERTIES 2.2. CHEMICAL PROPERTIES 2.3. USES OF METHANOL 3. DIFFERENT PROCESSES FOR MANUFATURE OF ACETIC ACID 3.1 ANAEROBIC FERMENTATION 3.2 THE DIRECT OXIDATION OF N-BUTANE 3.3. ACETALDEHYDE OXIDATION 4. PROCESS SELECTION 4.1 THE SELECTED PROCESS 4.2 ADVANTAGES OF SELECTED PROCESS 5. PROCESS DESCRIPTION 6. MATERIAL BALANCES 6.1 INTRODUCTION 6.2 MATERIAL BALANCE FOR ACETIC ACID PURIFICATION COLUMN FOR THE LIGHT END DISTILLATION COLUMN (DC-1) 6.4 MATERIAL BALANCE FOR REACTOR 7. ENERGY BALANCES 7.1INTRODUCTION 7.2 ENTHALPY BALANCE FOR REACTOR 7.3 ENTHALPY BALANCE FOR LIGHT END DISTILLATION COLUMN 7.4. ENERGY BALANCE FOR DISTILLATION COLUMN CALCULATION OF COOLING WATER REQUIREMENT 7.6 CALCULATION OF STEAM REQUIREMENT i ii iii iv

5 8. EQUIPMENT DESIGN 8.1 AVERAGE MOLECULAR WEIGHT CALCULATION 8.2 NUMBER OF STAGES CALCULATIONS FOR DC-I 8.3 INTERNAL DESIGN ESTIMATION 8.4 LIQUID FLOW PATTERN 8.5 PROVISIONAL PLATE DESIGN 8.6 CROSS CHECK 8.7 PLATE PRESSURE DROP 8.8 DOWN COMER LIQUID BACKUP 8.9 CHECK TO AVOID FLOODING 8.10 CHECK ENTRAINMENT 8.11 TRIAL LAYOUT 8.12 CHOOSING DOMEDHEAD AND CALCULATING ITS THICKNESS 8.13 STAGES CALCULATION FOR LIGHT END DISTILLATION COLUMN SHELL THICKNESS CONDENSER DESIGN REBOILER DESIGN 9. SIMULATION USING UNISIM DESIGN SUITE 10. MATERIALS OF CONSTRUCTION 11. SAFETY, HEALTH AND ENVIRONMENT ASPECTS 12. PLANT LOCATION 13. PLANT LAYOUT 14. COST ESTIMATION BIBLIOGRAPHY

6 ABSTRACT Plant design for manufacturing acetic acid Acetic acid has a place in organic processes comparable to sulfuric acid in the mineral chemical industries and its movements mirror the industry. Methanol carbonylation has become the technology of choice in the world market. Production from synthesis gas is increasing and the development of alternative raw materials is under serious consideration. Research on fermentative routes to glacial acetic acid is also being pursued. The main objective of the project is to discuss the design of a chemical plant for manufacture of acetic acid, this project will shows the industrialized processes employed in manufacturing of the acetic acid. The objective of the development of new acetic acid processes has been to reduce raw material consumption, energy requirements, and investment costs. Significant cost advantages resulted from the use of carbon monoxide and of low-priced methanol as feedstock s. At present, industrial processes (commercial process) for the production of acetic acid is dominated by methanol carbonylation route. This is the basic and outlined scope of the project that is needed to be carried out: Constructing a process flow diagram of the entire process Calculating mass and energy balances Equipment design and sizing Industry safety and hazard management Plant location Plant layout plans Project investment and costs i Page

7 LIST OF FIGURES Fig 1.1. Acetic acid global demand Fig 1.2. Acetic acid supply Fig 1.3. Global acetic acid consumption Fig 1.4. Acetic acid capacities Fig.1.5. Global acetic acid derivatives Fig 1.6. Acetic acid supply and demand Fig 3.1. Flow sheet for acetaldehyde oxidation Fig 5.1. Flow sheet for methanol carbonylation Fig 6.1. Material balance for Distillation column II Fig 6.2. Material Balance for Distillation column-i Fig 6.3. Reactor material balance Fig 8.1 Equilibrium stages for Distillation column Fig 8.2. Graph for to estimate Capacity Factor Fig 8.3. Graph for estimating Flow pattern Fig 8.4. Weep Point correlation Fig 8.5. Discharge coefficient for gas flow through sieve plates Fig 8.6. Graph for Fractional entrainment Fig 8.7. Relation between weir length, chord height and angle subtended by weir length Fig.8.8.Ft parameter versus S correlation Fig.8.9. Shell bundle clearance Fig Shell-side friction factors, segmental baffles Fig Tube-side friction factors Fig Tube-side friction factors Fig Plant Layout PAGE NO

8 LIST OF TABLES Table 6.1. Material balance for Distillation column 2 Table 6.2. Material balance for distillation column I Table 6.3. Material balance for Reactor Table 7.1. A,B,C,D & E constant values for different components Table 7.2. Enthalpy balance for feed out from CSTR Table 7.3. Energy balance for Distillation column 1 Table 7.4. Enthalpy balance for overhead stream Table 7.5. Enthalpy balance for bottom stream Table 7.6. Energy balance for feed stream Table 7.7. Energy balance for the overhead stream Table 7.8. Energy balance for the bottom stream Table 8.1.equilibrium data for distillation column -II Table 8.2. calculations for Relative volatility Table Total direct costs Table Total indirect costs Table Total fixed costs Table Total direct product costs Table 14.5.Total general expenses PAGE NO

9 NOMENCLATURE a,at,as B B Cp C D De dp,dt D F ID jh k L Nt ni OD P ΔP PT Q Qc Qr Rd ΔT U,Uc,Ud V Xf Xb Xd Flow area in general, for tube side, and for shell side, respectively Rate of Bottom Product Baffle spacing Specific heat Clearance between tubes Diameter Equivalent diameter Diameter of particle & tube respectively Rate of Distillate Product Rate of feed Inner Diameter Heat transfer factor, dimensionless Thermal conductivity Length Number of tubes Molar flow rate of component i Outer Diameter Pressure Pressure drop Tube pitch Heat flow Rate Condenser heat duty Reboiler Duty Dirt Factor Temperature Difference Overall heat transfer coefficient, clean coefficient, design coefficient Vapor Flow Rate in Rectifying Section Composition of Feed Composition of Bottom product Composition of Distillate

10 v w Latent Heat of Vaporization Viscosity Ratio ( w) Viscosity Viscosity at the tube wall Density Voidage

11 CHAPTER - I INTRODUCTION 1 Page

12 1.1. Introduction: Acetic acid is an important commodity used in chemical industries, with about 9 million tons of world demands per year. The primary use of this chemical is in the manufacture of assorted acetate esters, fungicide, organic compounds, organic solvents and the preparation of pharmaceuticals, cellulose acetate that is important in making film and plastic wares, perfumes and synthetic fiber. Acetic acid (CH3COOH), is a corrosive organic acid having a Sharp odor, Burning taste, and Pernicious blistering properties. It is found in ocean water, oilfield brines, rain, and at trace concentrations in many plant and animal liquids. It is central to all biological energy pathways. Fermentation of fruit and vegetable juices yields 2 12% acetic acid solutions, usually called vinegar (qv). Any sugar-containing sap or juice can be transformed by bacterial or fungal processes to dilute acetic acid. Theophrastus ( BC) studied the utilization of acetic acid to make white lead and Andreas Libavius (AD ) distinguished the properties of vinegar from those of ice like (glacial) acetic acid obtained by dry distillation of copper acetate or similar heavy metal acetates. Lavoisier believed he could distinguish acetic acid from acetous acid, the hypothetical acid of vinegar, which he thought was converted into acetic acid by oxidation. Uses include the manufacture of vinyl acetate and acetic anhydride. Vinyl acetate is used to make latex emulsion resins for paints, adhesives, paper coatings, and textile finishing agents. Acetic anhydride is used in making cellulose acetate fibers, cigarette filter tow, and cellulosic plastics. 2 Page

13 1.2 GLOBAL SCENARIO: A market study on glacial acetic acid discloses a large gap between its demand and supply. The production of acetic acid is sound globally but recent data shows a decreasing producing capacity of Asia worldwide. Most of Acetic acid produced in Asia is consumed internally and the excess is being imported due to its cheapness in the process involved. Fig 1.1. Acetic acid global demand Fig 1.2. Acetic acid supply 3 Page

14 A comparison of the demand and supply chart from the 2013 data supports the fact that with the demand of 12%, Europe producers are able to supply only 8% of it. The rest of the demand is being imported from producers from other continents. A study of world consumption of acetic acid in the year 2009 also reveals similar facts with china being the greatest consumer of acetic acid in the market and united states being the second most consumer. Fig 1.3. Global acetic acid consumption In a recent study, total worldwide production of virgin acetic acid is estimated at 5MMTPA (million metric tons per year), approximately half of which is produced in the United States. European production stands at approximately 1 MTA and is declining, and 0.7 MT is produced in Japan. Another 1.5 MT are recycled each year, bringing the total world market to 6.5 MTA. The two biggest producers of virgin acetic acid are Celanese and BP Chemicals. Other major producers include Millennium Chemicals, Sterling Chemicals, Samsung, Eastman, and Svensk Etanolkemi. Of the total global acetic acid capacity (virgin acid), 44% is in China, followed by 21% for the rest of Asia, 19% in the United States and 6% in Western Europe. These regions make up 90% of total world capacity CAPACITY OF ACETIC ACID: This section describes about the capacities and acetic acid derivatives production world wide 4 Page

15 Fig 1.4. Acetic acid capacities Fig.1.5. Global acetic acid derivatives Fig 1.6 acetic acid supply and demand 5 Page

16 1.3 INDIAN MARKET: With Asia s growing contribution to the global chemical industry, India emerges as one of the focus destinations for chemical companies worldwide. With the current size of $108 billion, the Indian chemical industry accounts for approximately 7% of Indian GDP. Share of industry in national exports is around 11%. In terms of volume, India is the thirdlargest producer of chemicals in Asia, after China and Japan. Despite its large size and significant GDP contribution, India chemicals industry represents only around 3% of global chemicals. The Indian chemical industry could grow at 11% P.A. To reach size of $224 billion by The demand for organic chemicals in India has been increasing at nearly 6.5% during this period and has reached the level of 2.8 million tons. The domestic supply has however grown at a slower pace resulting in gradual widening of demand supply gap which was primarily bridged through imports. Acetic Acid is primarily used for production of Purified terepthalic acid (PTA), Vinyl acetate monomer (VAM), and acetic anhydride and acetate esters. In India, production of acetic acid is primarily based on alcohol and its demand has grown at 10% during XI th Five Year Plan period. At present the consumption is estimated to be 0.6 million tons which would reach nearly 1.0 million tons by end of XII th Five Year Plan period ( ). The demand growth is primarily driven by end use demand from PTA which is basic raw material for polyester and fiber. There is substantial incremental capacity of PTA, driving demand for acetic acid in this segment. Acetic acid is primarily produced through alcohol or methanol route. Alcohol route in Indian context is gradually becoming unviable due to high prices and limited availability of this feedstock. At present bulk of acetic acid is imported with domestic production accounting for less than 30% of demand. Amongst the six major organic chemicals produced in India Acetic Acid contribute to nearly 2/3rd of Indian basic organic chemical industry. The balance 1/3rd of the organic chemical consumption in the country is accounted for by other wide variety of chemicals. 6 Page

17 CHAPTER - II PHYSICAL & CHEMICAL PROPERTIES AND USES 7 Page

18 2.1 PHYSICAL PROPERTIES: Acetic acid is a clear, colorless, corrosive liquid that has a pungent odor and is a dangerous vesicant. It has pungent vinegar like odor. The detectable odor is as low as 1 ppm. The liquid is usually available as glacial acetic acid with less than 1 Wt % water and over 98 % purity. Besides water, the acid contains traces of impurities such as acetaldehyde, oxidized substances, iron, and chlorides. Occasionally, the acid may be colored due to the presence of ethyl acetoacetate. The acetate is easily mistaken for formic acid because it reduces mercuric chloride. Traces of mercury may cause extensive corrosion by reaction with aluminum. Aluminum is a common material for containers to ship the acid.glacial acetic acid is very hydroscopic. The presence of 0.1 Wt % water lowers the freezing point significantly. Acetic acid forms azeotropes with many common solvents, such as benzene, pyridine, and dioxane. Acetic acid is miscible with water, ethanol, acetone, benzene, ether, and carbon tetrachloride. However, it is not soluble in CS2.The presence of acetaldehyde or formic acid is commonly revealed by permanganate tests. Though the molecular weight of acetic acid is 60.05, its apparent molecular weight varies with both temperature and the other associating substances present. It is miscible in all proportions with water, ethanol and ether. It is an excellent solvent for organic compounds. A zero dipole moment for unsymmetrical acetic acid structure(is explained by the formation of symmetric dimmers via hydrogen bonding in which the dipole moments cancel). No high dissociation ionic species in acetic acid solution. Possesses relatively low basicity or proton affinity. Has a very strong leveling effect on bases and solvolyzes all strong bases to acetate ion, CH3COO-. The physical properties are 1. Melting point 2. Boiling point : : C C 8 Page

19 3. Vapor pressure 4. Thermal conductivity : : W/m2 0C at 200C 5. Heat of melting 6. Heat of vaporization 7. Specific heat of vapor 8. Density : J/g : 394.5J/g at boiling point : J/g 0K at 1240C : g/ml at 200C 9. Refractive index,ηd 10. Specific heat of solid : : J/g 0K at 1000K 11. Critical pressure 12. Critical temperature : KPa (571.1 atm) : C 13. Magnetic susceptibility Solid Liquid : cm3/mol : cm3/mol 14. Dielectric constant Solid Liquid : at C : at 20.00C 15. Surface tension 16. Flash point, open cup 17. Auto ignition point 18. Lower limit of flammability : N/m or Dyne/cm at 20.10C : 570C : 465 0C : 400C : 5.4 vol% at 1000C 9 Page

20 2.2 CHEMICAL PROPERTIES: Many useful materials are made from acetic acid. Acetate esters are formed by reaction of olefins or alcohols with acetic acid. Acetic acid is also used in the preparation of pharmaceuticals. Aspirin (acetylsalicylic acid) is formed by the reaction between acetic acid and salicylic acid. This esterification reaction is reversible, however, and the presence of water can lead to hydrolysis of the aspirin. Thus, an anhydrous ( without water ) reagent could lead to better yields of product. Acetic anhydride can by prepared by the dehydration of acetic acid at 800OC. Alternatively, the reaction between the acid chloride and a salt of acetic acid (e.g. sodium acetate) yields acetic anhydride and a salt Reactions with inorganic compounds Acetic acid is mildly corrosive to metals including iron, magnesium, and zinc, forming hydrogen gas and salts called acetates: Mg + 2CH3COOH (CH3COO)2Mg + H2 Because aluminium forms a passivizing acid-resistant film of aluminium oxide, aluminium tanks are used to transport acetic acid. Metal acetates can also be prepared from acetic acid and an appropriate base, as in the popular "baking soda + vinegar" reaction: 10 P a g e

21 NaHCO3 + CH3COOH CH3COONa + CO2 + H2O Decomposition Reactions: Minute traces of acetic anhydride are formed when very dry acetic acid is distilled. Without a catalyst, equilibrium is reached after 7 hrs of boiling, but a trace of acid catalyst produces equilibrium in 20 min. Thermolysis of acetic acid occurs at 442OC and KPa (1 atm), leading by parallel pathways to methane and carbon dioxide, and to ketene and water. Both reactions have great industrial significance Acid Base Chemistry: Acetic acid dissociates in water, pka=4.76 at 25OC. It is a mild acid that can be used for analysis of bases too weak to detect in water. It readily neutralizes the ordinary hydroxides of the alkali metals and the alkaline earths to form the corresponding acetates. Other acids exhibit very powerful, super acid properties in acetic acid solutions and are thus useful catalysts for esterification of olefins and alcohols. Nitration conducted in acetic acid solvent are affected because of the formation of the nitronium ion, (NO2+) Hexamethylenetetramine may be nitrated in acetic acid solvent to yield the explosive cyclotrimethylenetrinitramine, also known as cyclonit or RDX Acetylation Reactions: Alcohols may be acetylated without catalysts by using a large excess of acetic acid. 2.3 USES OF ACETIC ACID: The various areas where acetic acid has its wide use are Over 60% of acetic acid produced goes into polymers derived from either Vinyl acetate (vinyl esters) or cellulose (cellulose esters). Most of poly (vinyl acetate) is used in paints and coatings or used for making poly (vinyl alcohol) and plastics. Also, cellulose acetate is used to produce acetate fibers. 11 P a g e

22 Acetic acid and acetate esters are used extensively as solvents and in organic Synthesis. In the production of white lead and chrome yellow pigments, it is used to make lead available in a soluble form for further reaction to give basic lead carbonate and lead chromate. Also used to provide the necessary acidity in the number of processes carried out in an aqueous media. Used in the mordanting process and in dyeing of wool in textile industry. Used as a coagulant for rubber latex in manufacture of elastic thread, as a component of photographic stopping and fixing baths and as a laundry sour. Also used in electroplating, engraving and in the processing offish glue. Dilute acetic acid functions either or both as a preservative and flavoring agent in food stuffs such as pickled vegetables, condiments, jellies and confectionery. RDX - The high explosive cyclotrimethylenetrinitramine is furnished on nitration of hexamethylenetetramine with acetic acid. Also, lower alkyl esters such as methanol, ethanol, isopropanol and butanol are widely used as solvents for lacquers and adhesives. Other esters form basis for synthetic flavors for perfumes and bornyl acetate in the manufacture of synthetic camphor Acetic acid is mainly utilized in the manufacture of the following products: 1. Acetic anhydride: Acetic anhydride is a very versatile product. It is a part of the manufacturing of Cellulose acetate fiber, Plastics, Vinyl acetate monomer etc. The pharmaceutical industry uses acetic anhydride as a dehydration agent. The dye industry also uses it for manufacturing dyes and dye intermediates. Ordinance factories use it in the manufacture of explosives. Perfumes are also made by the use of acetic anhydride. Aspirin, Paracetamol and other antibiotics are also made by using acetic anhydride. 2. Vinyl acetate: Vinyl acetate is a basic raw material for Poly vinyl acetate and Poly vinyl alcohol. Vinyl acetate monomer is used in the manufacture of latex paint, paper coatings, adhesives and textile finishing. 12 P a g e

23 3. Cellulose acetate: Cellulose acetate is an important constituent of thermoplastics and fibers. The textile industry uses cellulose acetate widely for the production of cellulose acetate fiber. The other uses of Cellulose acetate are the production of film, plastic sheets and the formulation of liquor. 4. Monochloro acetic acid: Monochloro acetic acid [MCA] is used extensively in the manufacture of Herbicides, Preservatives, Bacteriostat and Glycine. Mainly it is used in the manufacture of Carboxy methyl cellulose which is a gummy and strong adhesive powder used in drilling for oil. MCA is also used for producing laboratory chemicals like EDTA and 2 4 D Thioglucolicacid. 5. Purified Terepthalic acid [PTA]: Acetic acid finds use in the manufacture of PTA as a solvent. PTA is an alternative raw material for polyester fiber manufacture instead of Dimethyl terephthalate [DMT] 6. Food Additives [vinegar]: Acetic acid is widely used in the form of vinegar as a food additive. As vinegar it is used for the preservation of food and also to impart a sour taste to certain preparations. 13 P a g e

24 CHAPTER - III DIFFERENT MANUFACTURING PROCESSES 14 P a g e

25 The 99.8% pure acetic acid, sold in the name of glacial acetic acid can be manufactured by various processes. Each process is discussed in detail in the following sections. Different processes employed for manufacture of acetic acid: There are mainly three processes that produce acetic acid. They are Acetaldehyde Oxidation Methanol Carbonylation Anaerobic fermentation Butane Naphtha Catalytic Liquid-Phase Oxidation While in the Indian scenario acetaldehyde oxidation process takes the majority of acetic acid production. Alcohol is used to obtain Acetaldehyde (Alcohol is obtained by the fermentation and distillation of Molasses). Acetic acid is produced by this route using a two-step process. i. Oxidation of alcohol to Acetaldehyde: C2H5OH +½O2 CH3CHO + H2O ii. Oxidation of Acetaldehyde to Acetic acid: CH3CHO +½O2 CH3COOH 3.1 ANAEROBIC FERMENTATION: Species of anaerobic bacteria Species of anaerobic bacteria, including members of the genus Clostridium or Acetobacterium can convert sugars to acetic acid directly, without using ethanol as an intermediate. The overall chemical reaction conducted by these bacteria may be represented as: C6H12O6 3CH3COOH These acetogenic bacteria produce acetic acid from one-carbon compounds, including methanol, carbon monoxide, or a mixture of carbon dioxide and hydrogen: 2CO2 + 4H2 CH3COOH + 2H2O 15 P a g e

26 This ability of Clostridium to utilize sugars directly, or to produce acetic acid from less costly inputs, means that these bacteria could potentially produce acetic acid more efficiently than ethanol-oxidizers like Acetobacterium. However, Clostridium bacteria are less acid-tolerant than Acetobacter. Even the most acidtolerant Clostridium strains can produce vinegar of only a few per cent acetic acid, compared to Acetobacter strains that can produce vinegar of up to 20% acetic acid. At present, it remains more cost-effective to produce vinegar using Acetobacter than to produce it using Clostridium and then concentrate it. As a result, although acetogenic bacteria have been known since 1940, their industrial use remains confined to a few niche applications. 3.2 THE DIRECT OXIDATION OF N-BUTANE: Oxidation of n-butane in the liquid phase is through Chemische Werke Huls process. This reaction can be carried out in three different ways as shown below: i. A vapor phase non-catalytic reaction at 350 to 4000C and 5-10 atm.pressure. ii. A liquid phase non-catalytic reaction at C and atm.pressure. iii. A liquid phase homogenous catalytic reaction at C and atm. pressure. ½ C4H10 + O2 CH3COOH + H2O The production of acetic acid by acetaldehyde oxidation has an extensive patent literature. It has been in commercial operation since 1911 in Germany and 1920 in the US. Even in many processes acetaldehyde is essentially an intermediate in the production of acetic acid and the four common main routes to acetaldehyde are: i) The vapor-phase dehydrogenation or partial oxidation of ethyl alcohol ii) The liquid-phase hydration of acetylene iii) The high-temperature oxidation of saturated hydrocarbons IV) The liquid-phase oxidation of ethylene. 16 P a g e

27 3.3. ACETALDEHYDE OXIDATION: The continuous oxidation of acetaldehyde in the liquid phase is generally carried out by using air or oxygen in the presence of catalyst manganese acetate. The reaction mixture containing acetaldehyde diluted with crude acid and manganese acetate solution is circulated upward through the oxidation tower. CH3CHO +½O2 CH3COOH Reaction conditions when air is used are C at psi (about 5 atm); and when air is used oxygen is used, C at a pressure sufficient to keep the acetaldehyde liquid. The reaction mixture is drawn off the top of the distillation tower and is diluted continuously in as many as 3 distillation columns. Now, crude acid is fed into the top of the distillation column and other volatile components are withdrawn overhead while a residue containing manganese acetate is removed at the bottom. A low boiling fore run is taken off overhead in the second column and % pure acetic acid is taken off just above the reboiler. The mechanism can be described in the following manner 17 P a g e

28 18 P a g e

29 In Hoechst Process, the oxidation is usually done with oxygen, which operates continuously at 50-70oC in the oxidations towers of stainless steel (bubble columns) with acetic acid as solvent. Temperatures of at least 50oC are necessary to achieve an adequate decomposition of peroxide and thus a sufficient rate of oxidation. The heat of reaction is removed by circulating the oxidation mixture through a cooling system. Careful temperature control limits the oxidative decomposition of acetic acid to formic acid, CO2, and small amounts of CO and H2O. Acetic acid selectivity reaches 95-97%. Besides CO2 and formic acid, the byproducts include methyl acetate, methanol, methyl formate, and formaldehyde, which are separated by distillation. 19 P a g e

30 CHAPTER - IV PROCESS SELECTION 20 P a g e

31 4.1 THE SELECTED PROCESS: Methanol Carbonylation route Undoubtedly the methanol carbonylation route has a much greater production when compared to any other processes i.e. it holds 75% of the world s acetic acid production technologies. Production of Acetic acid by carbonylation of methanol used to be done by a process named as Monsanto process where Rhodium catalyst was used as an active catalyst with iodide of metals such as lithium. The process was carried at bar pressure and at a temperature of 150 to 200oC giving a high selectivity of 99% based on the methanol feed. But B.P chemicals came up with a process named as Cativa that used Iridium catalyst with Hydrogen iodide as the active catalyst in the system. Henry Drefyus at British Celanese developed a methanol carbonylation pilot plant as early as However, a lack of practical materials that could contain the corrosive reaction mixture at the high pressures needed (200 atm or more) discouraged commercialization of these routes. The first commercial methanol carbonylation process, which used a cobalt catalyst, was developed by German chemical company BASF in In 1968, a rhodium-based catalyst (cis [Rh(CO)2I2] ) was discovered that could operate efficiently at lower pressure with almost no byproducts. The first plant using this catalyst was built by US chemical company Monsanto Company in 1970, and rhodium-catalyzed methanol carbonylation became the dominant method of acetic acid production. In the late 1990s, the chemicals company BP Chemicals commercialized the Cativa catalyst ([Ir(CO)2I2] ), which is promoted by ruthenium. This iridium catalyzed process is greener and more efficient and has largely supplanted the Monsanto process, often in the same production plants This overcame many limitations of the Monsanto process as Lower water concentration was obtained in the product compared to Monsanto process. The process now could be carried at a comparatively lesser pressure and temperature. The number of distillation units was reduced. Iridium is cheaper than Rhodium, hence reducing the cost of production to a large extent. The Cativa Process is carried bar pressure and at a temperature of oC giving a high selectivity of 99%(based on the methanol feed). 21 P a g e

32 The reactions are: Main reaction: CH3OH + CO CH3COOH H= -138kJ/mol Side Reactions: CH3OH + CO C2H5COOH CH3COOH + CH3OH CH3COOCH3 The process involves iodomethane as an intermediate, and occurs in three steps. A catalyst, usually a metal complex, is needed for the carbonylation (step 2). CH3OH + HI CH3I + H2O CH3I + CO CH3COI CH3COI + H2O CH3COOH + HI By altering the process conditions, acetic anhydride may also be produced on the same plant. Because both methanol and carbon monoxide are commodity raw materials, methanol carbonylation long appeared to be an attractive method for acetic acid production. The use of other less expensive catalyst such as nickel, palladium, and ruthenium in homogeneous systems has also been investigated. In 1996, BP Amoco commercialized the iridium-based Cativa technology, which operates with reactor water levels that are comparable to the improved Monsanto process. The new catalyst is most effective when used in combination with lithium and ruthenium. The Cativa technology is installed in Sterling s Texas City acetic acid plant, which has a capacity of 990 million lb/yr (450,000 t/yr) 22 P a g e

33 This is the catalytic cycle for the carbonylation of methanol using iridium as the catalyst 23 P a g e

34 4.2. ADVANTAGES OF SELECTED PROCESS: The selected process has following advantages over other processes: The selectivity of Cativa process is 99% as compared to the 90% of acetaldehyde oxidation and even lesser in other processes. The operation is cheaper than other processes. The methanol used as the feed is comparatively cheaper than the feed in other processes. Fermentation process which also seems viable in terms of operation involves a greater upstream and microbial growth. downstream cost for sterilization of equipment to provide an environment for The liquid phase reaction is easy to control. 24 P a g e

35 CHAPTER - V PROCESS DETAILS 25 P a g e

36 5.1 PROCESS DETAILS: The carbonylation process of methanol is carried out in a continuous stirred tank reactor. The methanol and carbon monoxide is fed to the reactor from the bottom as feed. The carbon monoxide is compressed in a compressor to 30 bar before inlet to the reactor to ensure the reaction is occurs in the liquid phase. The reaction is highly exothermic and hence a cooling jacket is provided outside the reactor to ensure that the proper temperature of 150oC is maintained in the reactor. The initial heat required to ignite the reaction is mainly rough age of steam through the jacket. As the reaction starts, the heat of reaction is used to continue the reaction and excess heat is removed. The following will be the process flow diagram for methanol carbonylation route. The unreacted gases are vented out through a scrubber which also works as a preheater for a part of methanol feed. A part of methanol feed is preheated from ambient temperature to 60oC as it comes out of the scrubber Another work that is performed by the side stream is the stripping of entrained liquid in the vent gases and it also ensures that the loss of product with these gases is minimal. The vent gases generally exit the scrubber at 50oC to the atmosphere. 26 P a g e

37 27 P a g e

38 The product stream from the CSTR, is rich in acetic acid and containing small concentrations of methanol, by-product propionic acid and water is made to pass through the throttling valve to the flash tank where the product is flashed to a reduced pressure of 1 atm. The product from the flash tank is fed to the light end distillation column at a temperature of 52oC. A recycle stream is pumped from the bottom of the flash tank back to the CSTR. In the light end distillation column the feed containing acetic acid, water, propionic acid, methanol and methyl acetate is distilled to separate light ends (methyl acetate and methanol) from the bottom stream containing acetic acid, propionic acid and little concentration of water. The acetic acid is generally 87.6 % by wt. which is further purified in the acid purification unit to obtain the required product. The feed stream enters at a temperature of about 52oC and the bottom stream leaves the end column at a temperature of 97oC. In the acid purification unit, the stream enters at a temperature of 97oC. The higher boiling component propionic acid is obtained from the bottom of the distillation tower where a temperature of 123oC is maintained. Glacial Acetic acid (99.8% by wt.) is obtained from the top of the distillation tower, maintained at 118oC. 28 P a g e

39 CHAPTER - VI MATERIAL BALANCE 29 P a g e

40 6.1. INTRODUCTION:- Material balance is the basis of process design. A material balance taken on complete process determines the quantities of material required and the products produced. Balance over individual process unit sets the process stream flows and compositions. Material balances are also useful tool for study of plant operation and trouble shooting. They can be used to check the performance against design to check instrument calibration and to locate the source of material loss. From literature, selectivity to acetic acid = 99% (based on Methanol Route). Yield of Acetic Acid = 90% Basis: 100 ton per day of Glacial Acetic Acid (product) It is known that 99.8% acetic acid by weight is to be obtained as the overhead product. Assumed capacity of the plant = 100 TPD = TPA Because the total working hours for a plant under operation per a year are 8000 hours so 334 days MATERIAL BALANCE FOR ACETIC ACID PURIFICATION COLUMN (DC-II): Hence for the 2nd distillation column (acetic acid purification column) the following data is known We have, XD = 0.998, XB = , XF = (all in Wt %) And D = 100 TPD = kg/hr of Acetic acid. Taking wt. per hour basis of acetic acid, B= ( ( ) ) = ( ) / ( ) 30 P a g e

41 = kg Thus, F = D + B = kg. Hence, the weight and wt. fraction can be arranged for DC-II in the table as: Fig 6.1. Material balance for Distillation column II The composition for the above components can be known from the tables Table 6.1. Material balance for Distillation column 2 COMPONENTS FEED FEED (wt) BOTTOM BOTTOM(wt) overhead Overhead (wt %) in kg (wt %) in kg H2O CH3COOH C2H5COOH TOTAL Now, as assumed remaining methanol is converted to methyl acetate during the throttling operation. Hence the amount of acetic acid remains constant and can be used to find the moles (and thus the wt.) of methanol to be used. Main Reactions: CH₃OH + CO CH₃COOH 31 P a g e

42 Side Reactions: CH₃OH + ½ CO CH₃OH + CH₃COOH C2H5COOH CH₃COOCH Let the moles of methanol taken be x Kmol. Also, yield = conversion selectivity We have conversion = 90.91%. Taking mole balance on the reactor itself, we have: CH₃OH + CO CH₃COOH x Kmoles of MeOH + x Kmoles of CO x Kmoles of AA unreacted MeOH = ( ) x = x kmoles Hence, this methanol is used in production of methyl acetate in the flash tank during the throttling process. But it is known that we obtain 1000 ppm of methanol from the tank output. Thus, Methanol consumed in flash tank = x x = x kmoles CH₃OH + CH₃COOH CH₃COOCH₃ + H2O x kmoles of reactants x kmoles of products Total CH3COOH to light end distillation feed = x x = x Kmoles But, the kmoles of Acetic acid in the flash tank output Hence, actual methanol requirement = Kmoles = 69.28/ = Kmoles Also, total water is produced in propionic acid and methyl acetate reaction. Total water produced = = 8.37 Kmoles 32 P a g e

43 Total water in light end distillation column feed = 9.13 Kmoles Carbon monoxide is taken 7.2%in excess than the methanol feed. Moles of carbon monoxide = 107.2% = Kmoles CO is the excess reagent and Methanol is the limiting reagent. Considering overall material balance assuming the reactor, scrubber and flash tank as a complete system we have, Mass of gas in vent = Mass of methanol in + Mass of carbon monoxide in Mass of feed in light end distillation column Mass of vent from scrubber = = kg Also, 20% in excess promoter, i.e. Hydrogen Iodide and Iridium Catalyst is assumed to be used in the reactor. Hence, weight of catalyst = 20% excess of feed methanol = Kg = Tons This catalyst is recycled back to the reactor from the flash tank and hence is not required to be fed again and again MATERIAL BALANCE FOR THE LIGHT END DISTILLATION COLUMN (DC-I): Fig 6.2. Material Balance for Distillation column-i 33 P a g e

44 Table 6.2. Material balance for distillation column I Compone Feed Feed Feed Bottom Botto Botto Overhe Overhe Overhe nts weight Wt Kmol Wt m m ad Wt ad Wt% ad (Kg/hr) % es (Kg/hr) Wt% Kmol (Kg/hr) Kmoles es Acetic acid Water Methanol Propionic acid Methyl acetate 8 Total MATERIAL BALANCE FOR REACTOR: Fig 6.3. Reactor material balance Table 6.3. Material balance for Reactor Component Kmoles Wt (Kg/hr) Wt % Methanol Water Acetic acid Propionic acid Total P a g e

45 CHAPTER - VII ENERGY BALANCE 35 P a g e

46 7.1. INTRODUCTION: In the process design energy balances are made to determine the energy requirements of the processes: the heating, cooling and power required in the plant operation an energy audit on plant will show the pattern of energy usage and suggest the areas for energy conservation & solving. General equation for conservation of energy: Energy out = Energy in + generation consumption - accumulation The process is considered as perfectly steady state and accumulation of both mass and energy will be zero. General form for heat capacity of a particular compound will be = A + B T + C T2 and ΔHi = 298 K is the reference temperature or datum temperature. Where n is the number of moles of the particular component TR is the temperature required. Table 7.1. A,B,C,D & E constant values for different components A B C D E Methanol Carbon monoxide Acetic acid Water Propionic acid Methyl acetate P a g e

47 7.2. ENTHALPY BALANCE FOR REACTOR: Specific heat of methanol entering at 30oC will be (Methanol) = ( T) T2 And ΔHi at 300C = = ( ) n = = Kmole/hr Now = ( ) Which is equal to KJ/Kg Specific Enthalpy of methanol at 30⁰C = KJ/Kg Now specific heat of Carbon monoxide entering at 30oC will be (Carbon monoxide) = ( ) ( ) ( ) And ΔHi at 300C = = ( ) ( ) ( ) n = / 28 = Kmoles/hr Now = ( ) ( ) ( ) Which is equal to KJ/Kg. Specific enthalpy of carbon monoxide = KJ/Kg Now calculating the total enthalpy of the streams 1. Methanol stream entering at 30⁰C 37 P a g e

48 Methanol steam rate Specific Enthalpy of methanol at 30⁰C Water stream rate Enthalpy of water Total enthalpy for the stream = Kg/hr = KJ/Kg =13.68 Kmole/hr = KJ/Kmole = Enthalpy of methanol +Enthalpy of water = ( )+( ) = KJ/hr 2. Carbon monoxide stream entering at 30⁰C Carbon monoxide stream rate Specific enthalpy of carbon monoxide Enthalpy of Carbon monoxide stream = Kg/hr = KJ/Kg = = KJ/hr Now we perform the total enthalpy calculations for the feed output from the CSTR at 150oC Now so the equation will be (Acetic acid) = ( T) + ( T2 ) And ΔHi at 1500C = =n ( ) ( ) n = / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg 38 P a g e

49 Specific heat of Propionic acid leaving at 150oC will be (Propionic acid) = ( T) + ( T2) And ΔHi at 150oC = =n ( ) ( ) n = / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg (water) = ( T) + (8.125 T2) + ( T3) + ( T4) And ΔHi at 150oC = =n ( ) ( ) ( ) ( ) n = / 18 = 9.13 Kmoles/hr Now = ( ) ( ) ( ) ( ) This will be equal to KJ/Kg Specific heat of methanol leaving at 150oC will be (Methanol) = ( T) T2 And ΔHi at 150oC = 39 P a g e

50 =n ( ) ( ) n = / (32.045) = Kmole/hr Now = ( ) ( ) Which is equal to KJ/Kg Table 7.2. Enthalpy balance for feed out from CSTR Component Specific enthalpy (KJ/kg) Kg/hr KJ/hr Acetic acid Propionic acid Methanol Water Total Total gases (vent) out of the scrubber: Mass of the vent gases out of the scrubber = Kg/hr Enthalpy of vent gases Enthalpy of total gases out of the scrubber = KJ/Kg = ( ) KJ/hr = KJ/hr Heat gained by methanol stream We know that heat of reaction H = -138KJ/mole = KJ/Kmole Flow rate of acetic acid Rate of heat required to start the reaction = Kmole/hr = = KJ/hr 40 P a g e

51 Making overall energy balance for reactor:- Energy in + Energy generated = Energy out + Energy accumulated Energy accumulated = Energy in + Energy generated - Energy out Energy in = Enthalpy of methanol stream + Enthalpy of CO stream = = KJ/hr Energy generated Energy out = Heat required to start the reaction = KJ/hr = Enthalpy of total gases out of the Scrubber = = KJ/hr Energy accumulated = = KJ/hr We have to assume any random temperature for cooling water which is less than the ambience So cooling water is at 17⁰C and leaves the reactor at 80⁰C. Heat gained by cooling water Heat gained by cooling water Specific heat of water, T = heat accumulated in the reactor = mass of cooling water Cp of water T = 4.18 KJ/Kg K = (80-17) ⁰C = 63⁰K Mass of cooling water required by reactor = Energy accumulated in reactor / (4.18 (80-17)) = / ( ) = Kg/hr 41 P a g e

52 Specific heat of methanol entering at 52oC will be (Methanol) = ( T) T2 And ΔHi at 520C = = n ( ) ( ) Now = ( ) ( ) Which is equal to KJ/Kg Specific heat of Propionic acid entering at 52oC will be (Propionic acid) = ( T) + ( T2) And ΔHi at 52oC = =n ( ) ( ) n = / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg Now specific heat of Acetic acid entering at 52oC will be (Acetic acid) = ( T) + ( T2) And ΔHi at 52oC = =n ( ) ( ) n = / = Kmoles/hr 42 P a g e

53 Now = ( ) ( ) This will be equal to KJ/Kg Specific heat of water entering at 52oC will be (water) = ( T) + (8.125 T2) + ( T3) + ( T4) And ΔHi at 150oC = =n ( ) ( ) ( ) ( ) n = Kg/hr / 18 = 9.13 Kmoles/hr Now = ( ) ( ) ( ) ( ) This will be equal to KJ/Kg Now specific heat of methyl acetate entering at 52oC will be (Methyl acetate) = (270.9 T) And ΔHi at 52oC = =n ( ) n = / = Kmoles/hr Now = ( ) This will be equal to KJ/Kg 43 P a g e

54 7.3. ENTHALPY BALANCE FOR LIGHT END DISTILLATION COLUMN (DC-1):- Table 7.3. Energy balance for Distillation column 1 Component Feed (Kg/hr) Specific Enthalpy (KJ/hr) 52⁰C Propionic acid Acetic acid Water Methanol Methyl acetate Total Now specific heat of methyl acetate leaving at 62oC will be (Methyl acetate) = (270.9 T) And ΔHi at 52oC = =n =n ( ) n = / = Kmoles/hr Now = ( ) This will be equal to KJ/Kg water) = ( T) + (8.125 T2) + ( T3) + ( T4) And ΔHi at 150oC = 44 P a g e

55 =n ( ) ( ) n = / 18 ( ) ( ) = 9.13 Kmoles/hr Now = ( ) ( ) ( ) ( ) This will be equal to 2264 KJ/Kg Specific heat of methanol at 620C Cp(Methanol) = ( T) T2 And ΔHi at 620C = =n ( ) ( ) Now = ( This is equal to KJ/Kg. ) ( ) Enthalpy balance for overhead stream: Table 7.4. Enthalpy balance for overhead stream Component Overhead Kg/hr KJ/Kg KJ/hr Water Methanol Methyl acetate Total Specific heat of Propionic acid leaving at 97oC will be (Propionic acid) = ( T) + ( T2) And ΔHi at 97oC = =n ( ) ( ) 45 P a g e

56 n = / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg (Acetic acid) = ( T) + ( T2 ) And ΔHi at 97oC = =n =n ( ) ( ) n = Kg/hr / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg Specific heat of water leaving at 97oC will be (water) = ( T) + (8.125 T2) + ( T3) + ( T4) And ΔHi at 97oC = =n ( ) ( ) n = / 18 ( ) ( ) = 9.13 Kmoles/hr Now = ( ) ( ) ( ) ( ) This will be equal to KJ/Kg 46 P a g e

57 Table 7.5. Enthalpy balance for bottom stream Component Bottom Kg/hr KJ/hr KJ/Kg Propionic acid Acetic acid Water Total Calculation for cooling water requirement: Amount of cooling water used by condenser = Mass of vapor being condensed Specific enthalpy of water = Heat accumulated in the overhead stream Amount of cooling water used by condenser = mass of cooling water specific heat of water T Mass of cooling water Specific heat of water T=Heat accumulated in the overhead stream m (4.18 (25-17)) m = KJ/hr = / (4.18 (25-17)) = Kg/hr Overall energy balance over DC-I: Feed enthalpy + Enthalpy of steam = Overhead enthalpy + Bottom enthalpy Total enthalpy of steam = Overhead enthalpy + Bottom enthalpy - Feed enthalpy = = KJ/hr If there are losses for example let us assume it as 5% Steam should provide energy = (1+0.05) = KJ/hr Steam entering at 120⁰C and leaving at 100⁰C as saturated liquid Amount of steam used = Mass of steam Specific heat of water at 100⁰C T 47 P a g e

58 mass of steam specific heat of water at 100⁰C T = energy provided by steam mass of steam 4.22 ( ) mass of steam = KJ/hr = / (4.22 ( )) = Kg/hr 7.4. ENERGY BALANCE FOR DISTILLATION COLUMN-II: Specific heat of Propionic acid entering at 97oC will be (Propionic acid) = ( T) + ( T2) And ΔHi at 97oC = =n ( ) ( ) n = / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg Now specific heat of Acetic acid entering at 97oC will be (Acetic acid) = ( T) + ( T2 ) And ΔHi at 97oC = =n ( ) ( ) n = / = Kmoles/hr Now = ( ) ( ) This will be equal to KJ/Kg 48 P a g e

59 Specific heat of water entering at 97oC will be (water) = ( T) + (8.125 T2) + ( T3) + ( T4) And ΔHi at 97oC = =n ( ) ( ) ( ) ( ) Now = ( ) ( ) ( ) ( ) This will be equal to KJ/Kg Enthalpy balance about Distillation Column-II : Table 7.6. Energy balance for feed stream component feed (Kg/hr) KJ/hr (KJ/Kg) Propionic acid Acetic acid Water Total Now specific heat of Acetic acid leaving at 118oC will be (Acetic acid) = ( T) + ( T2 ) And ΔHi at 118 oc = =n ( ) ( ) Now = ( ) ( ) This will be equal to KJ/ Kmole Specific heat of water leaving at 118oC will be (water) = ( T) + (8.125 T2) + ( T3) + ( T4) 49 P a g e

60 And ΔHi at 1180C= =n ( ) ( ) ( ) ( ) Now = ( ) ( ) ( ) ( ) This will be equal to KJ/Kmole. Now specific heat of Acetic acid leaving at 118oC will be (Acetic acid) = ( T) + ( T2 ) And ΔHi at 1180C = = n ( ) ( Now = ( ) ( This will be equal to KJ/ Kmole OVERHEAD STREAM SUMMARY : Table 7.7. Energy balance for the overhead stream Component Overhead Kmole/hr 1180C KJ/hr KJ/Kmole Acetic acid Water Total Specific heat of Propionic acid leaving at 123oC will be (Propionic acid) = ( T) + ( T2) And ΔHi at 1230C = =n ( ) ( 50 P a g e

61 Now = ( ) ( ) This will be equal to KJ/Kmole. Specific heat of water leaving at 123oC will be (water) = ( T) + (8.125 T2) + ( T3) + ( T4) And ΔHi at 123oC = =n ( ) ( ) ( ) ( ) Now = ( ) ( ) ( ) ( ) This will be equal to KJ/Kmole. Now specific heat of Acetic acid leaving at 123oC will be (Acetic acid) = ( T) + ( T2 ) And ΔHi = = n ( ) ( ) Now = ( ) ( ) This will be equal to KJ/ Kmole BOTTOM STREAM SUMMARY: Table 7.8 Energy balance for the bottom stream Component Bottom (Kmole/hr) 1230C (KJ/Kmole) (KJ/hr) Propionic acid Acetic acid Water Total P a g e

62 Heat Capacity summary of all Compounds, Cp Value in J/kmol.K (Acetic acid) = ( T) T2 (Methanol) = ( T) T2 (Carbon monoxide) = (28723 T) + ( T2 ) + ( T3) (Water) (Propionic acid) = ( T) + (8.125 T2) + ( T3) + ( T4) = ( T) + ( T2) (Methyl acetate) = (270.9 T) 7.5 CALCULATION OF COOLING WATER REQUIREMENT: Amount of cooling water used by condenser = m 4.18 (25-17) = Mass of vapor condensed Specific enthalpy of vapor = = KJ/hr m 4.18 (25-17) m = KJ/hr = / (4.18 (25-17)) = Kg Steam requirement for DC-II:- Overall energy balance for DC-II: Enthalpy of feed + Steam enthalpy = Overhead enthalpy + Bottom enthalpy Total enthalpy of steam = Overhead enthalpy + Bottom enthalpy - Enthalpy of feed = = KJ/hr If there are losses for example let us assume it as 5% 52 P a g e

63 Steam should provide energy = (1+0.05) = KJ/hr Steam entering at 120⁰C and leaving at 100⁰C as saturated liquid Amount of steam used = Mass of steam Specific heat of water at 100⁰C T Mass of steam specific heat of water at 100⁰C T = energy provided by steam Mass of steam 4.22 ( ) Mass of steam Mass of steam = KJ/hr = / (4.22 ( )) = Kg/hr Total steam and total cooling water requirement:- Now evaluating total cooling water requirement Total cooling water requirement Cooling water in reactor Cooling water in DC-I Cooling water in DC-II Total cooling water requirement = Cooling water in reactor + Cooling water in DC-I + Cooling water in DC-II = Kg/hr = Kg/hr = Kg/hr = = Kg/hr = TPD 7.6 CALCULATION OF STEAM REQUIREMENT: Total steam requirement Steam in DC-I Steam in DC-II Total steam requirement = Steam in DC-I + Steam in DC-II = Kg/hr = Kg/hr = = Kg/hr = TPD 53 P a g e

64 CHAPTER - VIII EQUIPEMENT DESIGN 54 P a g e

65 8.1. AVERAGE MOLECULAR WEIGHT CALCULATION:- From material balance we have Feed to the DC-II = Kg/hr of acetic acid Kg/hr of water Kg/hr of Propionic acid = Kg/hr Top product from DC-II = 99.8% purity of acetic acid Bottom product from DC-II = % purity of propionic acid Feed:- Total flow = Kg/hr Molefraction of acetic acid in feed = / = Average molecular weight calculation: Total no of feed moles = Kmoles/hr Average molecular weight = / = Kg/Kmole Distillate:- Total flow rate of distillate = Kg/hr Mole fraction of acetic acid in distillate = Average molecular weight calculation Total moles of distillate = = Kmole/hr Average molecular weight of distillate = / = Kg/Kmole Bottom: Total bottom flow rate Mole fraction of acetic acid Average molecular weight Total moles Average molecular weight = Kg/hr = = / total moles = Kmole/hr = / = Kg/Kmole 55 P a g e

66 8.2. Number of stages calculations for DC-2: Firstly, we need to know relative volatility We have following data for DC-2 from material balance XD=0.998, XF=0.876, XB=0.001 Calculation of relative volatility: We need to calculate the vapor pressures of acetic acid and propionic acid at 370K Vapor pressure for acetic acid: From perry s handbook we have values of acetic acid ( ) C1=53.27,C2= ,C3= ,C4= ,C5=6 As T = 370K lnp P P P Vapor pressure calculation for propionic acid From perry s handbook lnp = C1 + (C2/T) + C3 lnt + C4 TC5 Values for propionic acid are C1=54.552,C2= ,C3= ,C4= ,C5=6 ln P ln P P P = = = e = KPa = = = e9.941 = Kpa α = vapor pressure of acetic acid at 370K /vapor pressure of propionic acid at 370K α = / α = We know that y = (α x)/(1+( α-1) x) 56 P a g e

67 y = ( x)/( x) Form the above expression we have the following equilibrium data Table 8.1.equilibrium data for distillation column -II x Y As it is saturated liquid q=1 Now Rmin is calculated in the following way Rmin=(1/ α)((xd/xf)-( α (1-XD)/(1-XF)) Hence by substituting the values of α, XD, XF We have Rmin= Now R = 1.5 Rmin R = Now by giving equilibrium data and conditions in the excel VBA Macros we obtain the following curve Fig 8.1 Equilibrium stages for Distillation column 57 P a g e

68 Number of stages From the above curve Slope of the rectifying section line Slope of the stripping section line Assuming 80% efficiency Number of real stages =15 = =1.041 =15/0.8= INTERNAL DESIGN ESTIMATION: Total feed moles Top product vapor rate V Liquid rate Bottom product B Slope of the stripping section V L V B V V L L Top section: Top densities form perry s hand book ρv = Kmoles/hr = D (R+1) = ( ) = 116.8Kmole/hr = V slope of the rectifying section = = 84Kmole/hr = 8.269Kmole/hr =L /V =1.041 =L -B =1.041 V =1.041 V -B =0.041 V =8.269Kmole/hr = Kmole/hr = = Kmole/hr =3.038Kg/m3, ρl =934.36Kg/m³ Surface tension, σtop = N/m Bottom section: ρv ρl =3.119Kg/m³, = Kg/m³ 58 P a g e

69 Surface tension, σbottom = N/m Calculation of flooding velocity: Uflood = k k = Csb (σ/20)0.2 FLV = (L/V) ( ρv/ ρl)0.5 Now FLV,bottom = (3.119/ )0.5 = FLV,top = (3.038/934.36)0.5 = Now estimating the capacity factor From the Graph Fig 8.2. Graph for to estimate Capacity Factor Csb,Top=0.36 Csb,Bottom=0.35 General plate spacing would be 24inch Now Ktop = Csb,top (σtop/20)0.2 = P a g e

70 Kbottom = Csb,bottom ( σbottom/20)0.2 = Uflood,top = Ktop =1.6811m/s Uflood,bottom = Kbottom = 1.645m/s Let us assume that we are designing for 85% flooding at maximum vapor flow rate Uflood,bottom Uflood,top Maximum volumetric flow rate = = = 1.4m/s = 1.43m/s Bottom, Qv = bottom vapor flow rate average molecular weight of bottom/ (ρvbottom 3600) = Kmole/hr 70.24Kg/Kmole / (3.119 Kg/m³ 3600) =1.2616m³/s Top,Qv = 116.8Kmol/hr 59.77Kg/Kmol / (3.119Kg/m³ 3600) = 0.62m³/s Net area required bottom(base) = Qvbottom / Uflood,bottom = m³/s / 1.645m/s=0.7669m² Net area required for top = Qvtop/Uflood,top = 0.62 m³/s / m/s=0.368m² Downcomer area is equal to 12% of the total area Column cross section area Base= / 0.88 = m² Top = / 0.88 = 0.418m² Column diameter: Base = = m Top = = 0.737m So we take column diameter as m 60 P a g e

71 8.4. LIQUID FLOW PATTERN: This is determined by two parameters 1. Maximum liquid flow rate 2. Column diameter Maximum liquid flow rate = 84Kmol/hr 59.77/( ) = m/s And we know column diameter =1.0535m From fig vol6 Fig 8.3. graph for estimating Flow pattern We have the flow to be cross flow single pass. So single pass tray can be selected PROVISIONAL PLATE DESIGN Column diameter Dt = m Column area = m² 61 P a g e

72 Down comer area = 12% of the total area = m² Net area Active area,aa = Ac-Ad = Ac-2 Ad = = 0.77m² = = m² Hole area,ah Hole area = taking 10% of the active area = = m² Weir length is generally 76% of the column diameter = = 0.8m Since column operating at pressure above atmospheric pressure Weir height = 50mm Plate thickness = 5mm 8.6. CROSS CHECK: Maximum liquid rate = / 3600 =1.394Kg/s Minimum liquid rate at 70% turn down Height of liquid crest over the wear (How)max = Kg/s = 0.976Kg/s = 0.75 (1.394/(934.6 weir length))(2/3) = 0.75 (0.7756/( )2/3 = mm Clear liquid height =11.363mm (How)min = 0.75 (.976/( ))(2/3) = 8.96mm Clear liquid height At minimum flow rate,dh Hw +(How)min = = 58.96mm liquid 62 P a g e

73 Fig 8.4. Weep Point correlation From graph Kw=30.4 Actual minimum vapor velocity Ūh = ((Kw-0.90 (25.4-dh))/( ρv)(1/2)) = ( (25.4-5))/(3.038)(1/2) = 6.907m/s = minimum vapor flow rate/hole area = m³/s 0.7/ (70% turndown) = m/s Thus,the minimum operating pressure(13.335m/s) lies well above the weep point(i.e.when vapor velocity is 7.252m/s) Therefore,our design is safe from operating point of view 8.7. PLATE PRESSURE DROP:- The total plate pressure drop is given by ht = hd + hl + hr Dry plate drop hd = K1 + K2 (Vgh)² (ρv/ ρl) For sieve plate,k1=0 & K2= ( )/Cv² Discharge coefficient Cv =plate thickness/hole diameter = 5/5 = 1 63 P a g e

74 Fig 8.5. Discharge coefficient for gas flow through sieve plates Form fig Cv = 0.84 Velocity through holes Vgh hd = m³/s/ = 19.05m/s = K1+ K2 Vgh² (ρv/ ρl) Pressure drop due to static head hl = hw + (how)max = mm = mm Residual height hr = 12.5/ ρl = ³/ = mm The total pressure drop Dry plate drop hd ht = 51 (Uh/C0)² (ρv/ ρl) = 85.28mm liquid = hd + hl + hr 64 P a g e

75 = mm = mm 8.8. DOWN COMER LIQUID BACKUP The down comer and plate spacing must be such that the level of the liquid and froth in the down comer is well below the top of the outlet weir on the plate above. if the level rises above the outlet weir the column will flood In terms of clear liquid the down comer backup is given by hb hdc = hw + how + ht + hdc = 166 (Lwd/( ρl Am)² Aap hap = hap Lw Hap=height of the lower edge of the apron above tray = hw-(5 or 10) = = 40mm (this height is normally set at 5 to 10mm below the outlet weir height) Lw=weir length Aap Aap hdc hb = hap Lw = 40mm 0.8=0.032m² As Aap<Ad = 166 (1.394/( ))² = 33.8mm = mm clear liquid 8.9. CHECK TO AVOID FLOODING hb < 1/2(plate spacing +weir height) hb < 1/2( ) =329.8mm hb= mm < 329.8mm This is obvious Since hb<329.8mm,there will be no flooding at specified operating condition that tray spacing is acceptable Tr = Ad hb ρl/lwd = /1.394Kg/s = 17s As residence time is greater than 3 secs therefore it is satisfactory 65 P a g e

76 8.10. CHECK ENTRAINMENT: Percent flooding = Uv/Uf = 1.40m/s/1.682m/s = Fig 8.6. Graph for Fractional entrainment The percent of flooding is 82.6% and flow parameter at the bottom of distillation column is FLV = From the above graph Figure by using the above two parameters, the fractional Entrainment is found out to be ᵠ = which is well below the value = 0.1 Therefore our design is acceptable. Hence the achieved flooding is less than flooding at maximum flow rate (85%) our design is correct TRIAL LAYOUT: We are considering sectional construction plates Allowing 125 mm unperforated strip round plate and 125 mm wide calming zone 66 P a g e

77 From Figure below, at Lw/Dc =0.8/ = 0.76 Φ=99o Angle subtended by the edge of the plate will be = 810 Mean length, unperforated edge strips = (column dia 125mm) 3.14 (angle subtended by edge/1800) = ( ) 3.14 (81/180) = m Area of unperforated edge strips = ( ) m2 = m2 Mean length of calming zone = weir length width of unperforated strip = 0.8 m + ( ) m = m Area of calming zones = ( ) m2 = m2 Total area for perforations, Ap = (Aa) (area of edge strips) (calming zone area) = m m m2 = m2 Ah/Ap = m2 / m2 = Fig 8.7. Relation between weir length, chord height and angle subtended by weir length 67 P a g e

78 Number of holes Area of one hole Number of hole = m2 = / = 3375 Design pressure =1atm = bar = N/mm Design pressure, take as 10 per cent above operating pressure Therefore design pressure Typical design stress Cylindrical section: = = N/mm =145 N/mm2 e = ( )/((2 145)-( )) = 0.76mm Say 1mm 8.12 CHOOSING DOMEDHEAD AND CALCULATING ITS THICKNESS: 1. Try a standard dish head(torisphere) Crown radius Rc Knuckle radius Rk Assuming joint efficiency, J=1 =Di = m = = m ( ) ( ) Cs = ( ) e = 1.3 mm Thickness of the torispherical head e = 1.3 mm Trying standard ellipsoidal head, major to minor axes ratio =2:1 Thickness of ellipsoidal head, e = 0.76(Say 1mm) Hence we have ellipsoidal head as probably the most economical. Taking same thickness as wall 1 mm. 68 P a g e

79 8.13. STAGES CALCULATION FOR LIGHT END DISTILLATION COLUMN (DC-1): This calculation is done by FUG shortcut method (Fenskey,Underwood,Gilliland) We need to know the relative volatilities of the components.so we need to calculate the component vapor pressures. Antoine equation ln P =A- (B/(T+C)) From Coulson and Richardson volume 6, We have the following data of A,B,C Acetic acid : A= ,B= ,C= Propionic acid: A= ,B= ,C= Methyl acetate: A= ,B= ,C= Water: A= ,B= ,C= Methanol: A= ,B= ,C= Now calculating the pressures for the components at temperature 325K ln = A- (B/(T+C)) = ( /( )) = =62.33 mmhg ln = A- (B/(T+C)) = ( /( )) = = mmhg ln = A- (B/(T+C)) = ( /( )) = = mmhg = A- (B/(T+C)) = ( /( )) 69 P a g e

80 = = mmhg ln = A- (B/(T+C)) = ( /( )) = mmHg Calculation of relative volatilities: We assume that water is the light key component (LK) and methyl acetate as heavy key component (HK) αi = Pi/PHK Components = / = = 62.3/ = = / = = / = = / =1 Table 8.2. calculations for Relative volatility XF XD XB α C2H5COOH CH3COOH H2O CH3OH CH3COOCH Gilliland equation: ( ) 70 P a g e

81 2- Fenske equation: ( ) ( ) 3- Underwood equation: ( ) Where θ: is a relative volatility lies between the relative volatility of light and heavy components substituting α,xf, and q=1 (saturated liquid) we have the equation θ4 ( θ3 ) θ θ = 0 By solving we get θ = Rmin R = 0.19 = 1.5 Rmin = ( ) ( ) Nmin= 14 ( ) By substituting above all values we have N= 25 stages SHELL THICKNESS: For thickness we must follow the following configuration 1. Design pressure=1.1 operating pressure 2. Permissible tensile stress, F= 145 N/mm² 3. Joint efficiency factor, j= 1(for shell) 4. Inner diameter, Di=0.7721m 5. Corrosion allowance C=1.5m 71 P a g e

82 Shell thickness is given by ts = ( ) / (( ) 145) = 77.2 mm CONDENSER DESIGN: The molar flow rate of vapor into the condenser of a purification column is V = Kmol /hr Entering temperature of the condensate Leaving temperature of the condensate = 1180C = 600C = 391 K = 333 K The enthalpy of the vapor The enthalpy of the condensate = kj/kmol = kj/kmol Entering temperature of the cooling water Leaving temperature of the cooling water = 170C = 700C = 290 K = 343 K Standard plant requires the tubes of each having outer diameter 20 m.m and inner diameter 16.8 m.m and tube length of 4.88 m long made of admiralty brass Thermal condition of vapor: Totally condensed and no sub-cooling occurs. Here only the thermal design of the condenser is considered. The physical properties of the mixture will be taken as mean of those for Acetic acid (M.W=60.05) and propionic acid (M.W=74.09) at the average temperature. Heat transferred from vapor = ( ) / 3600 = KW Assume the overall heat coefficient = 75 W/m2 K as it is light organics-water system the overall heat transfer coefficient lies in the range of W/m2 K Mean temperature difference: The condensation range is small and the change in the saturation temperature will be linear. So the corrected logarithmic mean temperature is used. R = ( TH.in TH.out ) / ( Tw.out Tw.in ) = ( ) / ( ) = S = ( Tw.out Tw.in ) / ( TH.in Tw.in) = ( ) / ( ) = 0.52 Take a horizontal exchanger with condensation in the shell, four tube passes. For one shell and four tube passes Ft = 0.75 from the below Figure. 72 P a g e

83 Fig.8.8.Ft parameter versus S correlation ΔTlh ΔTm Trial area = (( ) - ( )) / ln (( ) /( )) = C = = C = / = m2 Surface area of one tube = π = 0.305m2 Number of tubes Using square pitch = / = 203 = Pt = = 25 m.m Tube bundle diameter = Db = d0 (Nt / K1)/n1 K1 for 4 pass and square pitch is and n1 is Db = 20 (1.512 / )1/2.263 = 1,148 m.m Number of tubes in the center row = Nr = Db / Pt = 1148 / 25 = 46 Shell-side coefficient: Estimate tube wall temperature by assuming the condensing heat transfer coefficient as 150 W/m2 0K Shell side mean temperature = ( ) / 2 = 890C Tube side mean temperature = ( ) / 2 = 43.50C Balancing the heat energy on both sides 73 P a g e

84 (89-TW) 150 = ( ) 75 Mean temperature condensate = ( ) / 2 = C Physical properties at C μl = 0.55 mns/m2 ll = kg/m3 KL = W/m0C TW = C Vapor density at mean vapor temperature = lv = (60.05 / 22.4) (273 / ( )) 10 = kg/m3 Ґh Nr (hc)b = WC / L Nt = ( / 3600) ( ) = kg/s.m = 2 46 / 3 = 30 = 0.95 KL (ll ( ll-lv ) g / μl Ґh )1/3 Nr-1/6 = ( ( ) 9.81) / )-1/3 (30)-1/6 = W/m2 0C Close enough to assumed value of 150 W/m2 0C. So no correction to Tw needed. Tube-side coefficient: Tube cross-sectional area = (π/4) ( )2 203 / 4 = m2 Density of water at 43.50C = 993 kg/m3 Tube velocity Inner heat transfer coefficient = hi = (0.71 / 993) (1 / ) = m/s = 4200 ( t ) Ut0.8 / di0.2 = 4200 ( ) / = W/m2 0C Fouling factors: As neither fluid is heavily fouling, use 550 W/m2 0C for each side and Kw = 30 W/m0C Overall coefficient: 1/U = 1/ / ln (20/16.8)/ /( ) + 20/( ) = U = W/m2 0C Close enough to the estimate, firm up design. Shell-side pressure drop: 74 P a g e

85 Use pull through floating head, no need for close clearance. Select baffle spacing = shell diameter, 45 percent cut Fig.8.9. Shell bundle clearance For calculated bundle diameter Db = 1148 m.m the clearance from the above graph Figure 8.9 is 97 m.m Shell inner diameter = shell bundle diameter + clearance = = 1245 m.m Using kern s method to make an approximate estimate Cross-flow area = As = ( Pt do ) Ds lb / Pt = ( ) / 25 = 0.31 m2 Mass flow rate based on inlet conditions = Gs = ( / 3600) (1 / 0.31) = kg/s.m2 Equivalent diameter = de = 1.27( Pt do2 ) / do = 1.27( ) / 20 = 19.8 m.m Vapor viscosity = mns/m2 Reynolds number, Re = / P a g e

86 = From this Reynolds number we can calculate shell side friction factors, and segmental baffles from the below graph in Figure 8.10 Fig Shell-side friction factors, segmental baffles From the above figure, the friction factor = jf = US = GS / lv = / = m/s Take the pressure drop as 40 % of that calculated using the inlet flow, neglect viscosity correction ΔPs = 8 jf ( DS / de ) ( L / lb) ( lv US2 / 2) ( μ /μw )-0.14 = (2/5) ( ) (1245 / 19.8) (4.88 / 1245) (12.87 (22.6)2 / 2) = 3.6psi Negligible, more sophisticated method of calculation not justified. Tube-side pressure drop: Viscosity of water = 0.66 mns/m2 Reynolds number = /( ) = P a g e

87 By using this Reynolds number we can calculate tube side friction factors from the below graph in Figure Fig Tube-side friction factors From the above graph, the friction factor jf = Neglect viscosity correction factor ΔPt = Np (8 jf (L/di) (μ/μw)-m + 2.5) l Ut2/2 = 4 ( (4.88/ ) +2.5) /2 = 7.8 psi This is an acceptable value REBOILER DESIGN: Consider a kettle type reboiler is used in purification column Physical properties of Acetic acid at atm Vaporization rate of Acetic acid Boiling point at atm Latent heat of the stream Critical pressure (PC) Mean specific heat liquid : kmol/hr : C : kj/kmol : atm : kj/kmol0c 77 P a g e

88 Calculation of heat loads: Sensible heat load (maximum) = ( ) = kj/kmol Total heat load = ( ) / 3600 = KW For light organics-water mixture, we use steam to vaporize the mixture. The range of overall heat transfer coefficient is in the range of W/m2 0C Assume U = 100 W/ m2 0C Mean temperature difference: Steam saturation temperature at 1 atm = 1000C ΔTm = = 17.80C Area required (outside) = Total head load / U ΔTm = / = m2 Select 56 mm of inner diameter and 60 mm of outer diameter plain U-tubes of nominal length = 9.6 m Number of U-tubes = Area required (outside)/area of each pipe = / ( ) = tubes Use square pitch arrangement, pitch = 1.5 tube outer diameter Use mostinski s equation Heat flux, based on estimated area = Q = = 90 mm = Total heat load / Area (outside) = / = 1.78 KW/m2 Heat coefficient = hnb is given by the equation hnb = (PC)0.69 (Q)0.7 (1.8(P/PC) (P /PC) (P/PC)10) P = operating pressure, = 1.4 atm PC = liquid critical pressure = atm Q = heat flux, W/m2 = KW/m2 Hnb = (571.1)0.69 ( )0.7 (1.8(1.4/ 571.1) (1.4/ 571.1)1.2+10(1.4/ 571.1)10) = W/m2 0C Take steam condensing coefficient as 1000 W/m2 0C Fouling coefficient 300 W/m2 0C and methanol fouling coefficient,essentially clean 500 W/m2 0C Tube material will be in plain carbon steel = 55 W/m 0C 1/U0 = (1/ ) + (1/500) + ( ln (60/56) ) / (60/56) (1/ /1000) U0 = W/m2 0C 78 P a g e

89 This is close enough to original estimate of 100 W/m2 oc for the design to stand. Myers and Kate give some data on boiling of methanol on banks of tubes. To compare the value estimate with their values an estimate of the boiling film temperature difference is required. = (108.6/ ) 17.8 = C Myers data, extrapolated gives a coefficient of around 100 W/m2 0C at a C temperature difference = 4826 W/m2 0C, so the estimated value of W/m2 0C is certainly on the safe side. Check maximum allowable heat flux. Use modified Zuber equation. Surface tension (estimated) = N/m ll = kg/m3 lv = kg/m3 Nt = 518 Qcb = Kb (Pt/Do) (λ) (σg (ll - lv) lv2)0.25 As square arrangement Kb = 0.44 Qcb = 0.44 (90/60) (23670) ( ( ) (3.119)2)0.25 = W/m2 = KW/m2 Applying a factor of 0.7, maximum flux rate should not exceed the value = = 3.49 KW/m2. Actual flux of KW/m2 is well below maximum allowable flux rate. 79 P a g e

90 CHAPTER -IX SIMULATION USING UNISIM DESIGN SUITE 80 P a g e

91 This chapter includes the study of comparison of handmade calculations and computer simulated results using UnisimTM design software. UniSim Design offers a high degree of flexibility because there are multiple ways to accomplish specific tasks. This flexibility combined with a consistent and logical approach to how these capabilities are delivered makes UniSim Design an extremely versatile process simulation tool. The usability of UniSim Design is attributed to the following four key aspects of its design: Event Driven operation Modular Operations Multi-flow sheet Architecture Object Oriented Design The simulation software UnisimTM which is designed by Honeywell is mostly used in many of the chemical and petro-chemical industries. UniSim design is the Honeywell s version of Hysis. Fluid Package is UniSim s terminology for a collection of data that includes all the thermodynamic, component, and reaction parameters required to run the model. Select UNIQUAC as this method provides maximum data for our chemicals. Having completed the process model we will now take a look at some of the facilities in UniSim that allow us to generate reports, do additional design tasks, and help with model development. REPORT: The following report is being generated from the simulation balance tool 81 P a g e

92 Fig.9.1. Flow sheet of simulation of manufacture of acetic acid. 82 P a g e

93 1 Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc 2 Company Name Not Available Calgary, Alberta CANADA Unit Set: Date/Time: SI Wednesday May , 12:18: Workbook: Case (Main) STATUS 11 OK Material Streams Fluid Pkg: All 14 Name top bottom FEED1 top1 bottom1 15 Vapour Fraction Temperature (C) * Pressure (kpa) * Molar Flow (kgmole/h) Mass Flow (kg/h) * Liquid Volume Flow (m3/h) Heat Flow (kj/h) e e e e e Name cstr out out methanol CO vout 23 Vapour Fraction Temperature (C) * * * Pressure (kpa) 3000 * * * Molar Flow (kgmole/h) Mass Flow (kg/h) 4895 * * 2538 * Liquid Volume Flow (m3/h) Heat Flow (kj/h) e e e e e Name lout 31 Vapour Fraction Temperature (C) Pressure (kpa) Molar Flow (kgmole/h) Mass Flow (kg/h) Liquid Volume Flow Heat Flow (m3/h) (kj/h) Compositions Fluid Pkg: All 40 Name top bottom FEED1 top1 bottom1 41 Comp Mole Frac (Methanol) * Comp Mole Frac (CO) * Comp Mole Frac (C3oicAcid) * Comp Mole Frac (M-Acetate) * Comp Mole Frac (H2O) * Comp Mole Frac (AceticAcid) * Name cstr out out methanol CO vout 48 Comp Mole Frac (Methanol) * * * Comp Mole Frac (CO) * * * Comp Mole Frac (C3oicAcid) * * * Comp Mole Frac (M-Acetate) * * * Comp Mole Frac (H2O) * * * Comp Mole Frac (AceticAcid) * * * Name Lout 55 Comp Mole Frac (Methanol) Comp Mole Frac (CO) Comp Mole Frac (C3oicAcid) Comp Mole Frac (M-Acetate) Comp Mole Frac (H2O) P a g e

94 60 61 Comp Mole Frac (AceticAcid) Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc 2 Company Name Not Available Calgary, Alberta CANADA Unit Set: Date/Time: SI Wednesday May , 12:18: Workbook: Case (Main) (continued) Energy Streams Fluid Pkg: All Name Heat Flow (kj/h) Qcondenser 5.786e+006 Qreboiler 5.656e+006 qc 1.541e+006 qr 2.239e Unit Ops 15 Operation Name Operation Type Feeds Products Ignored Calc Level 16 bottom1 bottom 17 DC-2 Distillation Qreboiler top No 2500 * 18 Qcondenser 19 FEED1 bottom1 20 DC-1 Distillation qr top1 No 2500 * 21 qc 22 VLV-100 Valve cstr out out No * CRV-100 Conversion Reactor methanol CO lout vout No * Qreboiler bottom1 STREAM NAME STREAM NAME Qcondenser Top Bottom Reflux Ratio Distillate Rate Reflux Rate Btms Prod Rate Fixed / Ranged: Stage: Fixed / Ranged: Stream: Specified Value Fixed Condenser Fixed 4167 kg/h * Reboiler 7 Main TS Condenser Condenser Reboiler Primary / Alternate: Flow Basis: Primary / Alternate: Flow Basis: Distillation: DC-2 Stage Stage Current Value CONNECTIONS Inlet Stream Outlet Stream MONITOR Specifications Summary kg/h 1.042e+004 kg/h kg/h Wt. Error e e-006 SPECS Column Specification Parameters Reflux Ratio Primary Molar Distillate Rate Primary Mass Lower Bound: Liquid Specification: Material Stream Wt. Tol * * * * FROM UNIT OPERATION TO UNIT OPERATION Abs. Tol * kg/h * kg/h * kg/h * Active On On Off Off Estimate On On On On bottom1 Used On On Off Off Upper Bound: --- Lower Bound: --- Upper Bound: P a g e

95 1 2 Company Name Not Available Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc Fixed / Ranged: Stream: Degrees of Subcooling Subcool to Name Vapour Temperature Pressure Molar Flow Mass Flow Std Ideal Liq Vol Flow Molar Enthalpy Molar Entropy Heat Flow Fixed Calgary, Alberta CANADA Primary / Alternate: Flow Basis: (C) (kpa) (kgmole/h) (kg/h) (m3/h) (kj/kgmole) (kj/kgmole-c) (kj/h) Unit Set: Date/Time: Distillation: DC-2 (continued) Condenser bottom e e+006 SI Column Specification Parameters Btms Prod Rate Primary Mass SUBCOOLING User Variables CONDITIONS Wednesday May , 12:18:06 Lower Bound: --- Upper Bound: --- bottom e e+005 PROPERTIES Name bottom1 bottom top qr FEED1 qc top1 bottom1 STREAM NAME STREAM NAME STATUS OK NOTES Description Distillation: DC-1 Reboiler 13 Main TS Condenser Condenser Reboiler Stage Stage CONNECTIONS Inlet Stream Outlet Stream top e e+006 Material Stream Qreboiler e+06 FROM UNIT OPERATION TO UNIT OPERATION Qcondenser e+06 bottom1 85 P a g e

96 60 61 MONITOR 1 2 Company Name Not Available Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc Reflux Ratio Distillate Rate Reflux Rate Btms Prod Rate Fixed / Ranged: Stage: Fixed / Ranged: Stream: Fixed / Ranged: Stage: Fixed / Ranged: Stream: Calgary, Alberta CANADA Specified Value Fixed Condenser Fixed Fixed Condenser Fixed * kgmole/h * Primary / Alternate: Flow Basis: Primary / Alternate: Flow Basis: Primary / Alternate: Flow Basis: Primary / Alternate: Flow Basis: Unit Set: Date/Time: SI Wednesday May , 12:18:06 Distillation: DC-1 (continued) Current Value Specifications Summary kgmole/h kgmole/h kgmole/h Wt. Error 5.391e e-007 SPECS Column Specification Parameters Reflux Ratio Primary Molar Distillate Rate Primary Molar Reflux Rate Primary Molar Btms Prod Rate Primary Molar Lower Bound: Liquid Specification: Wt. Tol * * * * Abs. Tol * kgmole/h * kgmole/h * kgmole/h * Active On On Off Off Estimate On On On On Used On On Off Off Upper Bound: --- Lower Bound: --- Upper Bound: --- Lower Bound: Liquid Specification: Upper Bound: --- Lower Bound: --- Upper Bound: CONDITIONS 43 Name FEED1 bottom1 top1 qr qc 44 Vapour Temperature (C) * Pressure (kpa) * Molar Flow (kgmole/h) Mass Flow (kg/h) * Std Ideal Liq Vol Flow (m3/h) Molar Enthalpy (kj/kgmole) e e e Molar Entropy Heat Flow (kj/kgmole-c) (kj/h) e e e e e PROPERTIES 55 Name FEED1 bottom1 top STATUS 59 OK 1 Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc 86 P a g e

97 cstr out out STREAM NAME STREAM NAME Company Name Not Available Calgary, Alberta CANADA Valve: VLV-100 Unit Set: Date/Time: SI Wednesday May , 12:18:06 Distillation: DC-1 (continued) NOTES Description CONNECTIONS Pressure Drop: 1000 kpa * Name Vapour Temperature Pressure Molar Flow Mass Flow Std Ideal Liq Vol Flow Molar Enthalpy Molar Entropy Heat Flow (C) (kpa) (kgmole/h) (kg/h) (m3/h) (kj/kgmole) (kj/kgmole-c) (kj/h) Inlet Stream Outlet Stream PARAMETERS Physical Properties User Variables CONDITIONS cstr out * * * e e+07 Name cstr out out PROPERTIES STATUS OK FROM UNIT OPERATION TO UNIT OPERATION out e e P a g e

98 1 2 Company Name Not Available Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc methanol CO vout lout Name Vapour Temperature Pressure Molar Flow Mass Flow Calgary, Alberta CANADA Conversion Reactor: CRV-100 Delta P kpa Std Ideal Liq Vol Flow Molar Enthalpy Molar Entropy Heat Flow Stream Name Stream Name Stream Name Physical Parameters Vessel Volume (C) (kpa) (kgmole/h) (kg/h) (m3/h) (kj/kgmole) (kj/kgmole-c) (kj/h) --- Unit Set: Date/Time: CONNECTIONS SI Inlet Stream Connections Outlet Stream Connections Energy Stream Connections PARAMETERS User Variables CONDITIONS methanol * * * e e+07 PROPERTIES Wednesday May , 12:18:06 From Unit Operation To Unit Operation From Unit Operation Duty kj/h CO * * * e e+07 Optional Heat Transfer: lout e e-01 Name methanol CO lout vout Conversion Reactor: CRV-100 STATUS OK Energy Stream Heating vout e e P a g e

99 1 1 2 Company Name Not Available Case Name:Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.uscC:\Documents and Settings\Administrator\Desktop\work\prun.usc methanol CO vout lout Methanol CO AceticAcid Rxn-1 Methanol CO C3oicAcid M-Acetate Name H2O AceticAcid Delta P kpa Components Calgary, Alberta CANADA Unit Set: Date/Time: Conversion Reactor: CRV-100 (continued) Stream Name Stream Name Stream Name Component Physical Parameters Rank Vessel Volume --- CONNECTIONS SI Inlet Stream Connections Outlet Stream Connections Energy Stream Connections PARAMETERS User Variables REACTION DETAILS Reaction: Rxn-1 Mole Weight REACTION RESULTS FOR : Global Rxn Set 0 Specified % Conversion Total Inflow (kgmole/h) Yes Extents Use Default Balance Wednesday May , 12:18:06 From Unit Operation To Unit Operation From Unit Operation Duty kj/h Actual % Conversion Total Reaction (kgmole/h) Optional Heat Transfer: Energy Stream Stoichiometric Coeff. Base Component Methanol Total Outflow (kgmole/h) Heating Reaction Extent (kgmole/h) * * * P a g e

100 Methanol CO AceticAcid Rxn-1 Methanol CO C3oicAcid M-Acetate Name H2O AceticAcid Company Name Not Available Calgary, Alberta CANADA Unit Set: Date/Time: Conversion Reactor: CRV-100 (continued) Components Component Cylinder Rank User Variables REACTION DETAILS Reaction: Rxn-1 Mole Weight REACTION RESULTS FOR : Global Rxn Set 0 Specified % Conversion Total Inflow (kgmole/h) Volume --- Diameter Base Elevation Relative to Ground Level Diameter Elevation (Base) Elevation (Ground) Elevation (% of Height) Diameter Elevation (Base) Elevation (Ground) Elevation (% of Height) Name Vapour Temperature Pressure Molar Flow (C) (kpa) (kgmole/h) (m) (m) (m) (%) (m) (m) (m) (%) Yes Extents Use Default Balance m RATING Sizing Vertical Nozzles methanol lout Diameter CONDITIONS methanol * * SI Wednesday May , 12:18: Actual % Conversion Total Reaction (kgmole/h) CO * * Stoichiometric Coeff. Base Component Reactor has a Boot: Height CO Height Methanol lout Total Outflow No Reaction Extent (kgmole/h) vout P a g e (kgmole/h) * * * vout

101 62 63 Mass Flow (kg/h) * * Honeywell International Inc. UniSim Design (R410 Build 17061) Page 10 of Company Name Not Available Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc Calgary, Alberta CANADA Unit Set: Date/Time: SI Wednesday May , 12:18: Conversion Reactor: CRV-100 (continued) CONDITIONS 11 Std Ideal Liq Vol Flow (m3/h) Molar Enthalpy (kj/kgmole) e e e e Molar Entropy Heat Flow (kj/kgmole-c) (kj/h) e e e e Workbook: DC-1 (COL2) STATUS 58 OK 1 2 Company Name Not Available Case Name: C:\Documents and Settings\Administrator\Desktop\work\prun.usc Name Vapour Fraction Temperature Pressure Molar Flow Mass Flow Liquid Volume Flow Heat Flow Name Vapour Fraction Temperature Pressure Molar Flow Mass Flow Liquid Volume Flow Heat Flow Calgary, Alberta CANADA Unit Set: Date/Time: Workbook: DC-1 (COL2) (continued) (C) (kpa) (kgmole/h) (kg/h) (m3/h) (kj/h) (C) (kpa) (kgmole/h) (kg/h) (m3/h) (kj/h) e e+006 Material Streams To e e+006 SI Wednesday May , 12:18: e+006 Fluid Pkg: To e e e+005 Compositions Fluid Pkg: All 91 P a g e All