capacity control

[atedionyahoo]

Refer to API 618 capacity of reciprocating compressors could be controlled by unloading device, clearance pocket and spillback control valve.
If five steps unloading (i.e. 0, 25, 50, 75 and 100% of full flow) are used in combination of spillback control valve, it is kindly requested to inform us about following questions,
1. Which flows are reported as maximum, normal and minimum flow for control valve sizing?
2. Is it necessary to report full flow of compressor as a shutdown case for this valve and consider it to CV calculation?
3. If the response to item 2 is yes ,so which DP will be considered for valve in settle out (shut down)case?

 

[ilan7]

Need to have all the numbers put together - flow and pressure drop across the said control valve, and then select and calculate the needed valve. It might be that more then one valve is needed, and might need an Orifice in the valve line. If you do not have anyone in the company that know how to calculate the valve or valves needed you can try and contact valves manufacturer (Fisher controls, Tyco Valves, Metso, Flowserve) representatives in your area and ask their advice for the needed system of valves.