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Department of Chemical & Biomolecular Engineering

Senior Design Reports (CBE) University of Pennsylvania

Year 2002

Production of Acetaldehyde from Acetic Acid Calvin daRosa

Aurindam Ghatak

University of Pennsylvania

University of Pennsylvania

Claire Pinto University of Pennsylvania

This paper is posted at ScholarlyCommons. http://repository.upenn.edu/cbe sdr/45

PRODUCTION OF ACETALDEHYDE FROM ACETIC ACID

Authors:

Calvin daRosa

Aurindam Ghatak

Claire Pinto

Faculty Advisor

Dr. John V ohs

April 9, 2002

Department of Chemical Engineering

University of Pennsylvania

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09 April 2002 Dr. John Vohs Prof. Leonard Fabiano Department of Chemical Engineering University of Pennsylvania Philadelphia, P A 19104

Dear Dr. Vohs and Prof. Fabiano:

Enclosed in this report is the completed economic analysis of our proposed process. The process is designed to produce and recover acetaldehyde at high purity from acetic acid. This process design recovers 12,818 lblhr of acetaldehyde by extractive distillation at 99.6 % weight purity. A second commodity chemical, ethyl acetate, is produced as a byproduct in this process and is purified by a series of distillation columns. Ethyl acetate is produced at a rate of 1,139 lblhr and purity of 99.6 weight percent.

Capital cost estimations and profitability analysis have been completed for our process. Financial modeling of our process assuming the price of acetic acid to be 0.16/lb yielded an Investors Rate of Return (IRR) of 11.4 % and a Total Capital Investment (TCI) of $47,242,990. This scenario is not economically feasible. However, when the price of acetic acid is taken to be $0.12/lb, the IRR and TCI are 18.5 % and $47,224,990 respectively. In the light of that fact that the possible legislation ofMTBE out of gasoline might make this process more economically attractive, the group recommends further research into the feasibility of such a plant and the possible future construction of the facility given the realization of the second scenario.

Sincerely,

~0?d4--Calvin P. daRosa

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Aurindam K. Ghatak

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Claire L. Pinto

TABLE OF CONTENTS

Abstract. ................... .......... . .................................. .. ........ ..... 5

Introduction.... . , .... . .................. .. ................................... , ........ 7

Process Flowsheet. .................. . ................................................ 13

Material Balance ...... ................... . ................................... . ....... 16

Process Description ................... . ......................................... . .... 23

Energy Balance and Utility Requirements ..... ............................ . ...... 35

Unit Descriptions ............ ..... . .................. . ................................ 39

Absorber . . .................... . .... ........ ................ 39

Compressor. .. . .............................. . ... .. . ....... 40

Condensers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Decanter... . ... . .. ...... . ........ . ......................... . 44

Distillation Columns ..... . ......... ...................... 44

Fired Heater. ...... . ................. . .............. . .. . ... 49

Flash VesseL ......... . .................................... 50

Heat Exchangers ......... . ........... . .................... 50

Mixers ....... ............................................... 53

Pumps .. .. . ..... . .......................................... . 54

Reactor. ...... .. ............... ... .... . .. .. ............. . ... 59

Reboilers .. ....... . .................. . .... . .... .. ....... ... . 61

Reflux Accumulators ........... .. ......... . .............. 63

Refrigeration System .. . ..... .................. ...... .. ... 65

Splitters . . .. .... .. ..... .. ... ....... ........ .. ......... . ...... 65

Stripper ............ .. .... .. ... ............ " . ... .. .. .... . .. 66

Tanks . . .. . .................................................. 67

Valve ................. ...... ........... ... . ....... .......... .. 70

Unit Specification Sheets .................. ...... . ...... . ........... . ..... . .......... 71

Equipment Cost Summary......... . ..... . ..... ...... . .. . .. . ...... . .... . ... . ........ 135

Fixed-Capital Investment Summary.................... ...... . ..... ... ... .... . .... 137

Important Considerations ...... , .... . ... . .. . .... .. ... '" .... .. ..... . ..... . .. ........ .141

Operating Cost and Economic Analysis ................. ...... . ..... .......... .. . 145

Conclusions and Recommendations ........... . .......... . ....... .. ........... . ... 159

Acknowledgements ........... ...... ................... . ..... . ... . .. ................. 161

Bibliography.... ........ , .. .. ..... . ....... . .......... . , ...... . .... .. ... ....... . ....... 162

Appendix A: Unit Cost Calculations . . ........ ... ..... .. .... . ..... . ..... ...... . .. .163

Appendix B: Utility Cost Calculations ... .. .................... . ... .... .......... .201

Appendix C: Aspen Plus Results ... . ... . .... . . .. ........ .. ... . ... . ........ . ..... ...207

Appendix D: Problem Statement. ... . .......... . ........... .. ........... ....... .... 269

Appendix E: Patent. .... . ....................... .. ... . ..... . , ..... ............. , ..... .273

Abstract Our group has designed a process to manufacture 101,520,000 lb/yr of acetaldehyde by hydrogenation ofacetic acid over a 20% wt. palladium on iron oxide catalyst. The reaction conditions used are the optimum according to a patent filed by Eastman Chemical (Tustin, et.al., U.S . Patent No. 6,121,498): temperature is range is from 557-599 of at a pressure of254 psi. The conversion of acetic acid in the reactor is 46 %, with selectivity of 86% to acetaldehyde. Major by-products are ethanol, acetone, carbon dioxide, and the light hydrocarbons methane, ethane, and ethylene. Acetaldehyde is purified in a series of steps: it is first absorbed with an acetic-acid rich solvent, then distilled to separate acetaldehyde from heavier components. A refrigerated condenser is then used to recover additional acetaldehyde from the vapor distillate of the main separation. Acetic acid is purified and recycled to the reactor to limit the amount of feedstock required. Ethyl acetate is produced as a by-product in the acetaldehyde distillation column and is purified and sold. The economics of the process is strongly dependent on the price of acetic acid, and we examined scenarios under which acetic acid was available at either $0.16/Ib or $0.12/Ib. The total capital investment in either situation is approximately $47,000,000. If acetic acid is available at $0. 16/1b, we estimate an IRR of 11.3 %, but if acetic acid can be purchased for $0.12/Ib the IRR is 18.5% after 20 years. It is our recommendation to pursue more research into projecting both the cost of acetic acid and the market for acetaldehyde. If acetic acid will be available at the lower price, the company should pursue production of acetaldehyde.

5

6

Introduction The main product manufactured in this process is acetaldehyde. Acetaldehyde was chosen as the primary product because of its wide use in industry and the profitability of its sale as a chemical of given purity. In addition to acetaldehyde, ethyl acetate is produced as a side product. Table 1 below shows basic chemical information concerning the products.

Table 1: P

Synonym Molecular Formula Molecular Weight CAS No. Melting point Boiling point Density

f f duct Acetaldehyde (grimary product) Ethanal C 2H 4O 44.05 75-07-0 -190.3 OF 69.6 OF 0.6149 g/cm J -

Ethyl Acetate {side product) Acetic acid ethyl ester CH 3COOC 2H s 88.0 141-78-6 -117 OF 171°F 1.108 g/cm J

I. Uses Acetaldehyde is primarily used in industry as a chemical intermediate, principally for the production of pyridine and pyridine bases, peracetic acid, pentaerithritol, butylene glycol and chloral. It is used in the production of esters, particularly ethyl acetate and isobutyl acetate (lARC V.36 1985; Chern. Prod. Synopsis, 1985). It is also used in the synthesis of crotonaldehyde as well as flavor and fragrance acetals, acetaldehyde 1,1­ dimethylhydrazone, acetaldehyde cyanohydrin, acetaldehyde oxime and various acetic esters, paraldehyde halogenated derivatives (lARC V.36, 1985). Acetaldehyde has been used in the manufacture of aniline dyes and synthetic rubber, to silver mirrors and to harden gelatin fibers (Merck, 1989). It has been used in the production of polyvinyl acetal

7

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resins, in fuel compositions and to inhibit mold growth on leather (lARC V.36, 1985). Acetaldehyde is also used in the manufacture of disinfectants, drugs, perfumes, explosives, lacquers and varnishes, photographic chemicals, phenolic and urea resins, rubber accelerators and antioxidants, and room air deodorizers; acetaldehyde is a pesticide intermediate (Sittig, 1985; Gosselin, 1984). Acetaldehyde, an alcohol denaturant, is a GRAS (generally recognized as safe) compound for the intended use as a flavoring agent (Furia and Bellanca, 1975; HSDB, 1997). It is an important component of food flavorings added to milk products, baked goods, fruit juices, candy, desserts, and soft drinks. In 1976, approximately 19,000 Ib of acetaldehyde were used as food additives, primarily as fruit and fish preservatives and as a synthetic flavoring agent to impart orange, apple and butter flavors. Ethyl acetate, the side product of this process, is widely used in printing inks, paints and coatings, pesticides, pharmaceuticals, laminations and flexible packaging.

II. Production i.

Reasons for entering the market

Acetaldehyde was first produced commercially in the United States in 1916. U.S. Production of acetaldehyde reached its peak in 1969 at approximately 1.65 billion lb (lARC V.36, 1985). There has been an overall decline in the demand for acetaldehyde due to the use of more economical starting materials for principal derivatives and a lower demand for some acetal derivatives (Chern. Prod., 1985). However, in recent times due to a decline in the number of suppliers and an increase in potential U.S. acetaldehyde exports, there is a vast potential for profitability in manufacturing acetaldehyde. In 1985,

8

estimated U.S. exports of acetaldehyde were 1.2 billion lb (Chemical Products Synopsis, 1985).

ii.

Alternative processes and their disadvantages

Acetaldehyde can be made commercially via the Wacker process, the partial oxidation of ethylene. The major disadvantage of that process is that it is very corrosive requiring very expensive materials of construction. Another major disadvantage is that the reaction is prone to over-oxidation of the ingredient, the products of which are thermodynamically more stable than acetaldehyde which is the partial oxidation product. This over oxidation of the ingredient reduces the yield of acetaldehyde produced and converts expensive ethylene into carbon oxides (Tustin, et al.). Acetaldehyde is also manufactured by oxidizing ethanol using air. A mixture of air and ethanol vapor is fed into a multi-tubular reactor. Temperature is maintained between 750-932 of (400-500 °C), and the pressure at 29.4 psi. The catalyst used is chromium activated copper. Vapor coming out of the reactor is passed through a scrubber and unreacted ethanol is separated and recycled. However, this process gives a relatively poor yield of acetaldehyde The process investigated in this report converts acetic acid into acetaldehyde. Acetic acid is relatively inexpensive and is available at $0.12-$0.16/lb. It can be generated from inexpensive methanol. Due to the possible legislation ofMTBE out of gasoline, there may be a worldwide glut of methanol, so any chemicals that use methanol may become much more economically attractive. That is why acetic acid is our starting material of choice.

9

The catalyst used in this process is 20% palladium on an iron oxide support. This catalyst gives a selectivity of 86% to the desired reaction at 46% acetic acid conversion. Though this process can also be effectively catalyzed by mercury compounds, the toxic nature of mercury makes it unfeasible.

iii.

Discussion of Production Method

The reaction is carried out in a packed bed reactor at a temperature range between 557 and 599 of. The following reactions occur in the reactor: CH)COOH + H2 -> CH)CHO + H 20 (main reaction)

(1)

CH)COOH + 2H2 -> CH)CH 20H + H 20

(2)

2CH)COOH -> CH)COCH) + CO2 + H 20

(3)

3CH)COOH + 9H 2 -> 2CH4 + C 2H 6 + C2~ + 6H20

(4)

Under reaction conditions, the selectivity to reaction (1) is 86%. This facilitates a good yield of acetaldehyde and further justifies the cost of the reactor conditions. The product is then passed through an absorber and then separated as the distillate using a fractional distillation column. The following reaction occurs in the distillation column to produce ethyl acetate: CH)COOH + CH 3CH20H -> CH3COOCH2CH3 + H 20

(5)

This generation of ethyl acetate in situ is beneficial as it facilitates an ethyl acetate-water azeotrope in the acetic acid separation column, which makes it easier to separate the acetic acid. This acetic acid is then recycled back to the reactor. After being separated from the water, first in a decanter and then by distillation, the ethyl acetate is purified to 99.6 % wt, and can be sold.

10

The Gulf Coast is the location of choice for this plant. This is primarily due the region being an industrial belt. As a consequence, storage facilities as well as raw materials are readily available and cheap. As mentioned in the problem statement, due to this choice of location, it is assumed that hydrogen can be purchased over the plant fence for $0.50Ilb at 200 psig. Additionally, the prices of utilities are relatively inexpensive. Natural gas is available at $2.30IMMBTU, cooling water is purchased at $0.33IMGal and steam at 35 psi at $2.46IMLbs.

III. Environmental issues and potential safety problems EP A regulates acetaldehyde under several Acts such as the Clean Air Act (CAA) and the Clean Water Act (CWA). EPA has established water quality criteria, effluent guidelines, rules for regulating hazardous spills, general threshold amounts and requirements for the handling and disposal of acetaldehyde wastes. Process enclosures, local exhaust ventilation and other engineering controls must be used to maintain airborne levels below maximum exposure limits. Acetaldehyde is an extremely flammable liquid and vapor. Its vapor may cause flash fires. It forms explosive peroxides and polymerizes, resulting in hazardous conditions. Acetaldehyde is therefore sold in stainless steel tanks with a refrigerating system to ensure that the temperature of the product does not rise above 15°C. Acetaldehyde is also a potential cancer hazard. High vapor concentration may cause drowsiness or irritation of the eye and respiratory tract. For eye protection, safety glasses with side shields and a face shield need to be worn by people with risk of exposure. Additionally, chemical resistant gloves, boots and protective clothing appropriate for the

11

risk of exposure need to be worn. Decontamination facilities such as eye bath, washing facilities and safety shower must be provided. Ethyl acetate, on the other hand, is not subject to EPA emergency planning requirements under the Superfund Amendments and Reauthorization Act (SARA) (Title III) in 42 USC 11022. However, ethyl acetate is an irritant of the eyes and upper respiratory tract at concentrations above 400 ppm [NLM 1992]. Ethyl acetate occasionally causes sensitization, with inflammation of the mucous membranes and eczema of the skin [Hathaway et al. 1991]. As a consequence, ethyl acetate is stored in a cool, dry, well-ventilated area in tightly sealed containers. Splash-proof chemical safety goggles or face shields and coveralls should be worn during any operation involving potential exposure to ethyl acetate.

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