(Solved): (b) You are working as a process engineer looking after the continuous ammonia recovery process sh ...

(b) You are working as a process engineer looking after the continuous ammonia recovery process shown in Figure Q1. A gaseous stream rich in ammonia and mixed with steam and air (A) undergoes a temperature reduction, to get a mixed stream (B) consisting of ammonia and water in both gas and liquid phases plus air-gas. The stream (B) enters a scrubber where it disengages into air-gas (D) and liquid (E) phases. A fraction of stream (E) containing ammonia and water is recirculated (C), whereas the remainder is drawn off as a product. Stream (F) is fresh water makeup. CW D CW A B F CW CW E FIGURE Q1. Assuming that the feed stream (A) and all its components are determined by the upstream plant conditions, answer the following: (1) Describe the control objective. (Short answer question) (2 marks) (ii) What is the total number of strategic variables involved in the process? (Calculated numeric Question) (2 marks) (ii) From the following list, select all the independent mass balance equations involved. (Multiple answer question) 1. (A)YNH3 = (E)XNH3 2. A=D 3. YNH3 + YH2O + Yair = 1 4. (A)Yair =D 5. A+F = D + E 6. A = (D)Yair 7. Yair + YH20 = 1 8. (A)YH2O + F = (E)XH20 9. (A)YH2O = (E)XH20 10.XNH3 +XH20 = 1 (3 marks) (iv) What are the total numbers for: (1) degrees of freedom; (2) wild variables, and (3) controlled variables? (Calculated numeric question) (4 marks) (V) From the calculated controlled variables, select from the following list which variable(s) would you control. (Multiple answer question) 1. XH20 2. A. XH20 3. XNH3, D 4. XNH3 5. F, YAIR, D, E (2 marks) (vi) In the following diagram, select the area/areas where you would implement the selected control(s). (Hot spot question) CW B CW CW (2 marks) (vii) In the following figure, select the regions where inventory controls are needed (if any). (Hot spot question) CW CW CW CW B (3 marks)