Background information/introduction (& how this as Assignment Essay Help

Background information/introduction (& how this as Assignment Essay Help

Design Statement 2 The Design Design a process to produce 1 ? 108 kg per year of acrylonitrile (CH2:CH.CN) from propylene and ammonia by the ammoxidation. Feedstock: Ammonia: 100% NH3; Propylene: Commercial grade containing 90% C3 H6 and 10% paraffins. Services available: Dry saturated steam at 140 ?C. Cooling water at 24 ?C. The Process Propylene, ammonia, steam, and air are fed to a vapor-phase catalytic reactor (item A). The feed stream composition (molar percent) is propylene 7; ammonia 8; steam 20; air 65. A fixed-bed reactor is employed using a molybdenum-based catalyst at a temperature of 450 ?C, a pressure of 3 bar absolute, and a residence time of 4 seconds. Based upon a pure propylene feed, the carbon distribution by weight in the product from the reactor is: Acrylonitrile: 58%, Acetonitrile: 2%, Carbon dioxide: 16%, Hydrogen cyanide: 6%, Acrolein: 2%, unreacted propylene: 15%, Other byproducts: 1%. The reactor exit gas is air-cooled to 200 ?C and then passes to a quench scrubber (B) through which an aqueous solution containing ammonium sulfate 30 wt% and sulfuric acid 1.0 wt% is circulated. The exit gas temperature is thereby reduced to 90 ?C. From the quench scrubber (B) the gas passes to an absorption column (C) in which the acrylonitrile is absorbed in water to produce a 3 wt% solution. The carbon dioxide, unreacted propylene, oxygen, nitrogen, and unreacted hydrocarbons are not absorbed and are vented to atmosphere from the top of column (C). The solution from the absorber (C) passes to a stripping column (D) where acrylonitrile and lower boiling impurities are separated from water. Most of the aqueous bottom product from the stripping column (D), which is essentially free of organics, is returned to the absorber (C), the excess being bled off. The overhead product is condensed, and the aqueous lower layer returned to the stripping column (D) as reflux. The upper layer which contains, in addition to acrylonitrile, hydrogen cyanide, acrolein, acetonitrile, and small quantities of other impurities, passes to a second reactor (E) where, at a suitable pH, all the acrolein is converted to its cyanohydrin. (Cyanohydrins are sometimes known as cyanhydrins.) The product from the reactor (E) is fed to a cyanohydrin separation column (F), operating at reduced temperature and pressure, in which acrolein cyanohydrin is separated as the bottom product and returned to the ammoxidation reactor (A) where it is quantitatively converted to acrylonitrile and hydrogen cyanide. The top product from column (F) is fed to a stripping column (G) from which hydrogen cyanide is removed overhead. The bottom product from column (G) passes to the hydroextractive distillation column (H). The water feed rate to column (H) is five times that of the bottom product flowfrom column (G). It may be assumed that the acetonitrile and other byproducts are discharged as bottom product from column (H) and discarded. The overhead product from column (H), consisting of the acrylonitrile water azeotrope, is condensed and passed to a separator. The lower aqueous layer is returned to column (H). The upper layer from the separator is rectified in a column (I) to give 99.95 wt% pure acrylonitrile. Aspects of the design work required Process Design Sketch the block flow diagram showing the major processes. Present a material balance for the process. Work out a heat balance for the reactor (A) and quench column (B). Prepare a process flow diagram showing the items of major equipment, pipelines and control instruments. Indicate the instrumentation and safety procedure required for this process bearing in mind the toxic and flammable materials being handled. Chemical Engineering Design Present a chemical engineering design of reactor (A) and either column (B) OR column (D). References Towler G, Sinnott R (2013) Chemical Engineering Design, 2nd ed. (Elsevier)2. Perona JJ and Thodos G (1957) AIChE J, 3, 2303. Kolb, HJ and Burwell RL (1945) J Am Chem Soc, 67, 10844. Rudd, DF and Watson, CC (1968) Strategy of Process Engineering (New York: John Wiley & Sons Inc.) Requirement The assessment criteria to the report are: Abstract (10%), Introduction (10%), Process and Equipment Design (60%), which includes: process design, chemical engineering design of specific processes, flowsheet development and specific equipment design if applicable, Discussion (10%), Conclusion (5%) and Reference (5%). The design project requires efficient communication among the members of the group, e., meetings should be held to discuss allocations of specific tasks to individual members of the group and to report their progresses towards their assigned tasks. Each member of the group should focus on what they are initially allocated and set the target (timeline) in order for their work to be combined into the group report. Cakculate the cost of project.


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