Download GTU BE/B.Tech 2019 Winter 7th Sem New 2170507 Computer Aided Process Synthesis Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- VII (New) EXAMINATION — WINTER 2019

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1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1

1. Draw the superstructures for one cold stream and three hot streams. MARKS 03
2. Explain the ‘process creation’ step briefly in product and process design. 04

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3. Calculate the number of possible sequences of ordinary distillation column for 10 number of product and draw only direct and indirect sequences. 07

OR

Q.1

1. Write a short note on threshold approach temperature and optimum approach temperature for heat exchanger networks. 07

Q.2

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1. Describe the criteria for selection of separation methods. 03
2. Explain marginal vapor rate method. 04
3. A given batch plant produces one single product for which stage 1 requires 8 hours/batch; stage 2, 4 hours/batch and stage 3, 7 hours/batch. If zero — wait transfer is used, what is the cycle time? How many parallel units should be placed in each stage to reduce the cycle time to 4 hours? 07

OR

Q.2

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1. Describe the use of composite curves to select utility. 03
2. Write a note on Networks for Maximum Energy Recovery. 04
3. Draw the stream matching diagram above pinch temperature by considering pinch temperature in hot stream 125°C from the data given as follows. Assume ?Tmin = 13°C. 07

Stream | Source, Ts (°C) | Target, Tt (°C) | MCp (kW/°C)

H1 | 175 | 45 | 10

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H2 | 125 | 65 | 40

C1 | 20 | 155 | 20

C2 | 40 | 112 | 15

Q.3

1. Calculate the minimum number of heat exchangers for heat exchanger network involving three different streams and two distinct utility sources. All the streams in process are connected directly or indirectly by heat exchangers. 03

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2. Explain transshipment model for stream matching. 04
3. For, ?Tmin = 20°C, using temperature interval method, find the minimum utility requirements and pinch point for a network of heat exchangers involving the following streams: 07

Stream | Source, Ts (°C) | Target, Tt (°C) | MCp (kW/°C)

H1 | 260 | 160 | 3

H2 | 250 | 130 | 1.5

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C1 | 120 | 235 | 2

C2 | 180 | 240 | 4

OR

Q.3

1. Write briefly on Role of computers in process synthesis. 03

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2. Explain different Multiple Utility Design Problems in Heat Exchanger Networks. 04
3. Explain the heuristics for determining sequences of ordinary distillation columns and determine the best sequence for following problem: 07

Relative volatility

Feed rate, -

Feed component Component Relative

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kmol/hr . volatility

propane (C3) 454 C3/iC4 3.6

isobutene (iC4) 136.1 iC4/nC4 1.5

n-butane (nC4) 226.8 nC4/iC5 2.8

i-pentane (iC5) 181.4 iC5/nC5 1.35

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n-pentane (nC5) 317.5

Q.4

1. Discuss the properties of residue curve map. 03
2. What are the residue curves? Draw the residue curves for a system containing octane, ethylbenzene and 2-ethoxyethanol with boiling point 398.8 K, 409.2 K and 408.1 K respectively. 2-ethoxyethanol makes binary azeotrope with octane and ethylbenzene at 389.1 K and 400.1K respectively. 04
3. Consider a plant consisting of two stages that manufactures two products A and B. Demands are 500000 kg/yr for A and 300000 kg/yr for B and the production time considered is 6000 hr. Data for processing time, size factors and cleanup times are as follows: 07

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Processing time (hr) Size factors (m³/kg prod.)

Stage 1 Stage 2 Stage 1 Stage 2

A 8 3 0.08 0.05

B 6 3 0.09 0.04

Cleanup times: 4 hr A to B and B to A

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The production schedule is single product campaigns and length of production cycle is 1000 hr. Perform the sizing of vessels for the plant.

OR

Q.4

1. Define: Vapour Recompression and Reboiler Flashing 03
2. Discuss the concept of multi effect distillation as possibility of energy integration. 04

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3. We have a mixture of five alcohols labeled as A, B, C, D and E with flows in the feed of 1, 0.5, 1, 7 and 10 mol/s respectively, for a total of 19.5 mol/s and relative volatilities are 4.3, 4, 3, 2, and 1 respectively. The information about marginal vapor flows estimated for non-key species are as under: 07

A B C D E

A/B -- > 2.6 6.5 32

B/C 5.3 -- -- 9.3 4.0

C/D 24 1.3 -- -- 6.7

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D/E 1.5 0.8 2.0 - -

Find the best distillation based separation sequence.

Q.5

1. Explain the generalized rules for stream splitting on both sides of the pinch to satisfy MER requirements. 03
2. Define span and cycle time for batch processes. Explain various policies with example. 04

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3. Given the processing times for these products A, B, C, below. Determine with a Gantt Chart the make span and cycle time for manufacturing two batches of A, 1 of B and 1 of C for the following cases. 07

1. Zero-Wait policy with sequence AABC.
2. Same as 1) but with no intermediate storage policy (NIC)
3. Same as 1) but with unlimited intermediate storage policy (UIS)

(Processing Time)

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Stage 1 Stage 2 Stage 3

A 5 4 3

B 3 1 3

C 4 3 2

Zero Cleanup Times

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OR

Q.5

1. FirstRanker.com 03