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Get Full Access to Process Dynamics And Control - 3 Edition - Chapter 9 - Problem 9.2
Get Full Access to Process Dynamics And Control - 3 Edition - Chapter 9 - Problem 9.2

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# A process instrumentation diagram for a flash drum is

ISBN: 9780470128671 148

## Solution for problem 9.2 Chapter 9

Process Dynamics and Control | 3rd Edition

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Problem 9.2

A process instrumentation diagram for a flash drum is shown in Fig. E9.2. Steam is condensed in a steam coil to vaporize a portion of the liquid feed, and the liquid product is removed by a pump. There are control valves for the steam flow, vapor product, liquid product, feed flow, and steam chest (which allows the steam chest to be rapidly evacuated in emergency situations). Determine whether the five valves should be fail-close (F/C) or fail-open (F/0) for safe operation, for each of three cases: (a) The safest conditions are achieved by the lowest temperature and pressure in the flash vessel. (b) Vapor flow to downstream equipment can cause a hazardous situation. (c) Liquid flow to downstream equipment can cause a hazardous situation. Discuss various scenarios of air failure (or power failure).

Step-by-Step Solution:

Problem 9.2A process instrumentation diagram for a flash drum is shown in Fig. E9.2. Steam iscondensed in a steam coil to vaporize a portion of the liquid feed, and the liquid product isremoved by a pump. There are control valves for the steam flow, vapor product, liquidproduct, feed flow, and steam chest (which allows the steam chest to be rapidly evacuatedin emergency situations). Determine whether the five valves should be fail-close (F/C) orfail-open (F/0) for safe operation, for each of three cases:(a) The safest conditions are achieved by the lowest temperature and pressure in the flashvessel.(b) Vapor flow to downstream equipment can cause a hazardous situation.(c) Liquid flow to downstream equipment can cause a hazardous situation. Discuss variousscenarios of air failure (or power failure). Step-by-step solution Step 1 of 3 ^There are control valves for the steam flow vapor product, liquid product, feed flow, and steamchest in a process instrumentation diagram for a flash drum (Refer to Figure E9.2 in the Textbook).(a)The safest conditions are achieved by keeping temperatures and pressures lowest in the flashvessel. To achieve this condition, the following set-up has been required:VALVE 1:- Fail closeVALVE 2:- Fail openVALVE 3:- Fail openVALVE 4:- Fail openVALVE 5:- Fail closeSet valve 1 as fail-close puts off more heat from entering into flash drum and set valve 3 asfail-open permits the steam chest to drain. Set valve 3 as fail-open puts off pressure build-up inthe vessel. Valve 4 should be fail-open to vacate the system and help in maintaining thepressure low. Valve 5 should be fail-close to stop any further pressure build-up.

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##### ISBN: 9780470128671

The answer to “A process instrumentation diagram for a flash drum is shown in Fig. E9.2. Steam is condensed in a steam coil to vaporize a portion of the liquid feed, and the liquid product is removed by a pump. There are control valves for the steam flow, vapor product, liquid product, feed flow, and steam chest (which allows the steam chest to be rapidly evacuated in emergency situations). Determine whether the five valves should be fail-close (F/C) or fail-open (F/0) for safe operation, for each of three cases: (a) The safest conditions are achieved by the lowest temperature and pressure in the flash vessel. (b) Vapor flow to downstream equipment can cause a hazardous situation. (c) Liquid flow to downstream equipment can cause a hazardous situation. Discuss various scenarios of air failure (or power failure).” is broken down into a number of easy to follow steps, and 133 words. Process Dynamics and Control was written by and is associated to the ISBN: 9780470128671. This textbook survival guide was created for the textbook: Process Dynamics and Control, edition: 3. Since the solution to 9.2 from 9 chapter was answered, more than 846 students have viewed the full step-by-step answer. This full solution covers the following key subjects: steam, flow, liquid, Product, instrumentation. This expansive textbook survival guide covers 24 chapters, and 420 solutions. The full step-by-step solution to problem: 9.2 from chapter: 9 was answered by , our top Engineering and Tech solution expert on 11/15/17, 04:03PM.

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