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We have a screw chiller compressor which is for refrigeration in recontact section of CCR naphtha Hydrotreating unit. We are trying to start it after TA but getting tripped after 3-4 sec. All electrical and rotary side are fine. It is having Interlock of PDI between lube oil discharge pressure and gas discharge pressure. Every time it trips on this and sometimes feed alarm fail comes.
Also filter on pump discharge was choked earlier.
Please suggest troubleshooting this problem.
 
Answers
20/06/2015 A: Amit Srivastava, Bharat Oman Refineries Ltd, amit.sri2610@gmail.com
Check the PDCV at the discharge of the pump for passing. if required start the pump keeping it isolated
13/06/2015 A: Faridul Qadar, IOCL, faridulqadar@gmail.com
Suggest check following items :-
1. PSVs of pump disch, oil filter & and oil entry to oil cooler are working ok
2. PDCV to reclaimed oil heater is working ok
3. Adequate disengaging space is given to propane in oil separator, less space can result in froth entering the pump and cavitation can happen, suggest to lower your oil level in separator (above tripping limits) to create more disengaging space.
4. oil pump strainer delta is normal
5. oil temperature to pump suction should be above 50 deg C, else heater should be inline
6. oil separator PSV should be working ok
08/06/2015 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Sounds to me like your lube oil filter is plugged, which causes low pressure differential between the lube oil and the gas discharge pressure. Filters plugging frequently on new systems is common, especially if a careful job was not done in cleaning out the piping after the project was completed. Dirt and welding debris is often not properly cleaned out of new equipment.