Based on the description of the process for the production of ethylene oxide from ethylene found in Appendix B of the Turton et al. textbook, you will evaluate the main performance indices of the process:
World conversion. One step conversion. Purity of the final product (mass percentage). Ethylene oxide recovery percentage in the absorbents and in the still. Amount of steam (low, medium and high) used per ton of product. Amount of booster water used per ton of product. Electrical energy consumption per ton of product. Product/raw material ratio (mass of ethylene oxide produced/mass of ethylene fed)
ETHYLENE OXIDE PRODUCTION, UNIT 700 Ethylene oxide is a chemical used to make ethylene glycol (the primary ingredient in antifreeze). It is also used to make polyethylene oxide, and both the low-molecular-weight and high-molecular-weight polymers have many applications including as detergent additives. Because ethylene oxide is so reactive, it has many other uses as a reactant. However, because of its reactivity, danger of explosion, and toxicity, it is rarely shipped outside the manufacturing facility but instead is often pumped directly to a nearby consumer. B.6.1 Process Description [1, 2] The process flow diagram is shown in Figure B.6.1. Ethylene feed (via pipeline from a neighboring plant) is mixed with recycled ethylene and mixed with compressed and dried air (drying step not shown), heated, and then fed to the first reactor. The reaction is exothermic, and medium-pressure steam is made in the reactor shell. Conversion in the reactor is kept low to enhance selectivity for the desired product. The reactor effluent is cooled, compressed, and sent to a scrubber, where ethylene oxide is absorbed by water. The vapor from the scrubber is heated, throttled, and sent to a second reactor, followed by a second series of cooling, compression, and scrubbing. A fraction of the unreacted vapor Figure B.6.1 Unit 700: Ethylene Oxide Process Flow Diagram Appendix B Information for the Preliminary Design of Fifteen Chemical Processes Appendix B Information for the Preliminary Design of Fifteen Chemical Processes 99 100 Appendix B Information for the Preliminary Design of Fifteen Chemical Processes Appendix B Information for the Preliminary Design of Fifteen Chemical Processes 101 102 Apperidix 3 Infonmation for the Preliminary Design of Fifteen Chemical Processes Table B.6.2 Utilitv Summarv Table for Unit 700 Table B.6.3 Maior Eauloment Summarv for Unit 700 Appendix B Information for the Preliminary Design of Fifteen Chemical Processes 103 104 Appendix B Information for the Preliminary Design of Fifteen Chemical Processes Table B.6.3 Major Equipment Summary for Unit 700 (Contioued) Table B.6.3 Naior Eauioment Summarv for Unit 700 (Continued) stream is purged, with the remainder recycled to recover unreacted ethylene. The combined aqueons product streams are mixed, cooled, throttled, and distilled to produce the desired product. The required purity specification is 99.5wt thylene oxide. Stream summary tables, utility summary tables, and major equipment specifications are shown in Tables B.6.1-B.6.3. B.6.2 Reaction Kinetics The pertinent reactions (adapted from Stoukides and Ivlou [3]) are as follows: C2H4+0.5O2C2H4OC2H4+3O22CO2+2H2OC2H4O+2.5O22CO2+2H2O The kinetic expressions are, respectively, r11+0.00098exp(11,200/RT)pethinx1.96exp(2400/RT)pattahs
