- You Have Just Been Hired As An Engineer For A Chemical Plant Your First Job Is To Explain Why The Production System Use 1 (50.43 KiB) Viewed 25 times
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Problem 6 (bonus 40 points) You have just been hired as an engineer for a chemical plant. Your first job is to explain why the production system used by your late predecessor exploded. First, he ran the liquid-phase reaction AB in a pilot-plant reactor. He had pretty strong evidence from the chemistry lab that it was a first- order irreversible reaction. The pilot-plant reactor was a jacketed kettle with a stirring device, operated as a CSTR. The kettle was not insulated, and saturated steam was run through the jacket. This run was successful, producing a 30% conversion of A. In addition, it was noticed that 2.47 Ib/hr of steam was condensed. After this run in the pilot-plant reactor, your predecessor decided that he could run the same reaction in a production reactor. The production reactor was also a jacketed kettle with a stirring device, operated as a CSTR, and it also was not insulated. Saturated steam was also run through the jacket. Since the production reactor was very similar to the pilot-plant reactor (except for size, of course), your predecessor thought there would be no trouble operating it. However, there was trouble. Very shortly after going on-stream, the reactor exploded. Why did the reactor explode? Justify your answer with numbers by predicting the operating temperature of the production reactor.
Additional Data for Problem 6 Feed: Pilot-plant reactor: Pure A Diameter: 1.29 Molecular weight: 100 Height: 1.29 Density: 50 lb/A Area for heat transfer: 6.54 ft- Heat capacity: 0.5 BTU/1b-°F Volume for reaction: 1.69 ft Temperature: 80°F Production reactor: Pilot-plant run: Diameter: 3.17 Volumetric feed rate: 6.67 ft /hr Height: 3.17 ft Molar feed rate: 3.33 lbmol Ahr Area for heat transfer: 39.5 ft? Conversion: 30% of A converted Volume for reaction: 25 ft Steam condensed: 2.47 lb/hr Production run: Volumetric feed rate: 100 ft/hr Molar feed rate: 50 lbmol A/hr Conversion: analytical instrument destroyed in explosion Reaction: Reaction is first order and irreversible, activation energy seems to be somewhere in the neighborhood of 32,400 BTU/lbmol Heat-transfer coefficients: Stirred liquid condensing steam: 500 BTU/hr-ft-F Stirred liquid/gas under forced convection: 50 BTU/hr-ft-F Condensing steam/gas under natural convection: 10 BTU/hr-ft-F Gas under convection/gas under natural convection: 5 BTU/hr-ft-OF Additional Data for Problem 6 (cont.) Miscellaneous: Density of reaction mixture: 50 lb/ft Heat capacity of reaction mixture: 0.5 BTU/Ib-°F Temperature of steam: 212 °F Temperature of air outside reactor: 75°F Heat of condensation of steam: 971 BTU/1b Boiling point of reaction mixture: 325°F The explosion occurred on a Wednesday The projected area of Rocky Mountain National Park: 415.3 mi (statute) Your course instructor's birthday is in November.