Question

2. Your next assignment is to retrofit an existing plant sketched in FIGURE Q2. Another process engineer has done some basic calculations for you. He gave you the information in TABLE Q2: Stream 1 25°C 40 kW/K R 100°C 150°C 1400 kW 80°C Storage 50°C C 60°C 40°C Storage Stream 2 50°C 50 kW/K 80°C 120°C 2800 kW RE Q2 TABLE Q2 Items Value Remark Allowable $\Delta T_{min}$ 20°C Hot pinch temperature 70°C Cold pinch temperature 50°C Minimum hot utility 150 kW Minimum cold utility 250 kW Overall heat transfer coefficient 1000 W/(m$^2$-°C) Price of hot utility RM 200/(kW-yr) Price of cold utility RM 20/(kW-yr) Cost of a new heat exchanger 8000 + 500$A^{0.75}$ (in RM) Cost of piping, additional Negligible areas, demolitions Perform the following: A is the heat transfer area (m$^2$) a. Identify several violations of the existing plant based on pinch rules. [5 marks] b. Retrofit the heat exchanger network (HEN) to obtain each hot and cold utility below 2000 kW. Only ONE heat exchanger can be added. Re- piping, additional areas, and demolition are allowed. Determine the annual utilities saving. 2 of 2 [15 marks]

          2.
Your next assignment is to retrofit an existing plant sketched in FIGURE Q2.
Another process engineer has done some basic calculations for you. He gave
you the information in TABLE Q2:
Stream 1
25°C
40 kW/K
R
100°C
150°C
1400 kW
80°C
Storage
50°C
C
60°C
40°C Storage
Stream 2
50°C
50 kW/K
80°C
120°C
2800 kW
RE Q2
TABLE Q2
Items
Value
Remark
Allowable $\Delta T_{min}$
20°C
Hot pinch temperature
70°C
Cold pinch temperature
50°C
Minimum hot utility
150 kW
Minimum cold utility
250 kW
Overall heat transfer coefficient
1000 W/(m$^2$-°C)
Price of hot utility
RM 200/(kW-yr)
Price of cold utility
RM 20/(kW-yr)
Cost of a new heat exchanger
8000 + 500$A^{0.75}$
(in RM)
Cost of piping, additional
Negligible
areas, demolitions
Perform the following:
A is the heat transfer
area (m$^2$)
a. Identify several violations of the existing plant based on pinch rules.
[5 marks]
b.
Retrofit the heat exchanger network (HEN) to obtain each hot and cold
utility below 2000 kW. Only ONE heat exchanger can be added. Re-
piping, additional areas, and demolition are allowed. Determine the
annual utilities saving.
2 of 2
[15 marks]

Show more…

2.
Your next assignment is to retrofit an existing plant sketched in FIGURE Q2.
Another process engineer has done some basic calculations for you. He gave
you the information in TABLE Q2:
Stream 1
25°C
40 kW/K
R
100°C
150°C
1400 kW
80°C
Storage
50°C
C
60°C
40°C Storage
Stream 2
50°C
50 kW/K
80°C
120°C
2800 kW
RE Q2
TABLE Q2
Items
Value
Remark
Allowable Δ Tmin
20°C
Hot pinch temperature
70°C
Cold pinch temperature
50°C
Minimum hot utility
150 kW
Minimum cold utility
250 kW
Overall heat transfer coefficient
1000 W/(m^2-°C)
Price of hot utility
RM 200/(kW-yr)
Price of cold utility
RM 20/(kW-yr)
Cost of a new heat exchanger
8000 + 500A^0.75
(in RM)
Cost of piping, additional
Negligible
areas, demolitions
Perform the following:
A is the heat transfer
area (m^2)
a. Identify several violations of the existing plant based on pinch rules.
[5 marks]
b.
Retrofit the heat exchanger network (HEN) to obtain each hot and cold
utility below 2000 kW. Only ONE heat exchanger can be added. Re-
piping, additional areas, and demolition are allowed. Determine the
annual utilities saving.
2 of 2
[15 marks]

Added by Stephanie C.

University Physics with Modern Physics

Hugh D. Young 14th Edition

Instant Answer

Solved by Expert Madhur L

06/15/2023

Step 1

- The cold pinch temperature is 50°C, but the minimum cold utility is 250 kW, which is higher than the allowable minimum. - The overall heat transfer coefficient is 1000 W/m2°C, which is not provided in the allowable range. Show more…

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Thanks for your feedback!

Looking at the attached image: Perform the following: a. Identify several violations of the existing plant based on pinch rules. [5 marks] b. Retrofit the heat exchanger network (HEN) to obtain each hot and cold utility below 2000 kW. Only ONE heat exchanger can be added. Repiping, additional areas, and demolition are allowed. Determine the annual utilities saving. 2 of 2 15 marks 2. Your next assignment is to retrofit an existing plant sketched in FIGURE Q2. Another process engineer has done some basic calculations for you. He gave you the information in TABLE Q2: Stream 1 25°C 40 kW/K 1400 kW 100°C 150°C 80°C 50°C Storage 80°C Stream 2 0.09 50 kW/K 80 120°C 2800 kW TABLE Q2 Items Allowable Tmin Hot pinch temperature Value Remark 20 70°C Cold pinch temperature 50 Minimum hot utility 150 kW Minimum cold utility 250 kW Overall heat transfer coefficient 1000 W/m2°C Price of hot utility RM 200/(kW-yr) Price of cold utility RM 20/(kW-yr) Cost of a new heat exchanger 8000+500A0.75 A is the heat transfer (in RM) area (m2) Cost of piping, additional Negligible areas, demolitions Perform the following: a. Identify several violations of the existing plant based on pinch rules. [5 marks] b. Retrofit the heat exchanger network (HEN) to obtain each hot and cold utility below 2000 kW. Only ONE heat exchanger can be added. Re-piping, additional areas, and demolition are allowed. Determine the annual utilities saving. 2.91 f15 marks

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Transcript

00:01 Hi, in this question in the first part we have the semantic representation of plant arrangement.

00:08 So, plant arrangement.

00:10 So, here we have outside then there is a main.

00:17 So, main or central plant.

00:20 So, or central plant then there is a hot duct.

00:28 So, hot duct where there is a heater battery.

00:31 So, heater battery and there is a cold duct where there is a cooler coil.

00:40 So, cooler coil then there is a shop a temperature control then there is a shop b temperature control.

00:59 So, this is about the plant arrangement.

01:01 Now we have in part b we have to calculate the mass flow rate of.

01:09 So, mass flow rate of a and b that is so, mass flow rate of cold and hot air.

01:20 So, cold and hot air that make up the supply air and moisture content of the supply air.

01:29 So, here to calculate the mass flow rate we need to consider the percentage of outside air.

01:34 So, for short pay we have outside air mass is.

01:38 So, mass flow rate for outside air is 0 .25 into total supply air flow rate and we have cold air mass flow rate will be equal to.

01:55 So, cold air mass flow rate will be equal to 0 .75 into total supply air flow rate then for shop b we have outside mass flow rate will be equal to 0 .25 into this total supply air flow rate and hot air mass ratio is 0 .75 into this quantity.

02:18 Now using psychometric calculation we can consider the cooler coil and heating coil...

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