Topic: Production of 150 000 metric ton per annum (MTAof Benzene by Dehydroalkyl

Question

Topic: Production of 150 000 metric ton per annum (MTAof Benzene by Dehydroalkylation of Toluene Process Description: A chemical plant producing 150 000 metric ton per annum of benzene from the dehydroalkylation of toluene, runs 24 hours per day for 330 days in a year. In the process the cold feeds to the reactor with a 5:1: 5.6 hydrogen (H2) to toluene (C7He) to methane (CH4) ratio is preheated in a feed effluent heat exchanger (FEHE) that recovers reaction heat from the hot reactor effluent (stream 13). A furnace brings the preheated reactor feed (stream 9) to a reactor inlett temperature of 621 C. The toluene dealkylates in a Plug Flow Reactor (PFR) to produce benzene (C6H6) and methane (CH4). A small amount of diphenyl (C12H10) by-product is also formed via coupling of two benzene molecules. The reactions are shown below: CTHB H2 C6H6 CH4 (Main Reaction) (1) 2C6H6 Hz C12H10 (Side Reaction) (2) The total amount of toluene fed into the reactor is 318.5 kmolhr and the selectivity of benzene compared to diphenyl i 44 mol CeHelmol C12H10. The hot reactor effluent (stream 11) is quenched to 612 oc to prevent further reaction and coking. It is cooled through the FEHE and the cooler to 38 °C. The amount of the quench liquid (stream 12) used is 58 kmol/hr with mole composition of 0.03 CH4, 0.75 C6H6, 0.21 CTHB and 0.01 C12H10. The cooled mixture is flashed in a flash drum at 38 0C and 25 bar to release the unreacted hydrogen and methane (steam 15) which is recycled back to the reactor (stream 7) after purging (stream 3) to provide an exit for the methane formed in the main reaction. The recycled hydrogen gas stream is mixed with a fresh hydrogen feed of 446.31 kmolhr. The amount of methane in the flash overhead stream is 90% of methane fed into the flash drum. The liquid from the bottom of the flash drum (stream 16) is fed to the separation section consisting of three columns which are the stabilizer, product and recycle distillation columns. The stabilizer column which operates at 38 0C and 2.5 bar, removes methane as the vapour overhead. The liquid bottoms is fed to the product column operating at 112 0Cand 2.5 bar with 100 mole pure benzene leaving a the distillate product. The bottoms from this column is fed to the recycle column that separates the diphenyl by-product as the bottoms with some toluene and takes pure toluene as the overhead distillate which is recycled back to the reactor after mixing with 254.46 kmolhr of fresh toluene feed.

Explanation / Answer

Please provide the question in a short and understable format so that it is easy to all of us to give a very effective and satisfactory answer. So that you can understand the answer easily . It is difficult to read and understand such a big question for everyone. Thankyu

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.