Question

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 s removed by a pump. There are ive 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 air-to-open (AO) or air-to-close (AC) for safe operation, for each of three cases: (a) The safest conditions are achieved by the lowest tempera ture 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) FC) (FT Vapor PT FT LT LC Steam 4 Condensate Liquid

Answer 1

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