Rotating Equipment Verification In Preparation for Service 2

[ghamsa]

We have new centrifugal pump and compressor, which are mechanically ready for placing in light hydrocarbon service. In short, the compressor will compress the propane gas and condense it through fin-fan cooler where the pump pumps the liquefied propane for further treatment.
My question is: how can I test or verify that the compressor or pumps are really ready for receiving the propane and no leaks or safety problems could happen when introducing the propane for the 1st time into these equipments?
Many thanks for your usual help

 

[ash9144]

Sounds like pressure test is what you need. Bring system up to and slightly above operating pressure with inert gas and check for leaks. Just be sure your relief valves or rupture disks are lined up and in service.

 

[ghamsa]

Thanks ash9144

what about the pumps?

 

[ash9144]

Fill your knock out drum with water. Route the discharge someplace safe and turn the pumps on. Someone should already have a plan for commisioning the equipment, or prestart up safety review. There are a lot of checks that need to occur before putting a new system on line (rotation checks, wiring, access, etc).

 

[SJones]

http://www.standard.no/pronorm-3/data/f/0/01/49/7_10704_0/Z-CR-007r1.pdf

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[dcasto]

OK, you already did your leak test, some people call it a hydrostatic test. Next your dried the system useing air to push the water out and draining the low spots. Next you purged the system of air, either by low pressure and low velocities until the air was removed OR by pressure/blowdown.

Now you should have a system with low pressure propane in it. Next, I'd bring in some liquid propane on a truck and fill the accumulator 20%. Turn the comprssors on with the recycle valve open and have the fans running. As you close the recycle valve, the pressure will rise to the accumulator pressure and the suction pressure will drop to the suction minimum pressure set pressure. Don't fully close the recycle valve if the minimum flow (or minimum suction pressure) control valve wasn't design for 100% recycle.

Check for leaks again, especilally round the isolation valves or isolation flanges and you drains. Watch temps and press on everything, including driver oil pressure or amps, or whatever.

Do the same with the pumps, close the discharge and make sure the minumum flow loop is open after you have purged like above. Close the dischage valve 95% (I like that because at 100% the valve may stick at firs), then hit the start button. watch for leaks and process conditions.

 

[ghamsa]

ash9144;

Should I turn on the compressor with inert gas or through external pressure source (hydrotest)?

thanks all

 

[pmover]

the compressor was designed to compress propane (MW=44). a readily available and inexpensive inert gas, such as nitrogen, has MW=28. a big difference, but you should note the differences in operating parameters.

others have posted good suggestions about starting a propane refrigeration system. I would highly recommend that you consult with the designer of the propane refrigeration system and obtain their input. a responsible designer should have the necessary technical skills to prepare the system comissioning, start-up, shutdown, and operational manual.

Having a competent, saavy, and knowledgeable on-site commissioning engineer(s) is beneficial as well.

Trying to start a propane refrigeration system without a commissioning/start-up manual is not good at all! there are many parameters to observe, not to mention operating and learning the control systems.

Good luck!
-pmover

 

[dcasto]

Do not run the compressor with nitrogen. for the same conditions of suction and discharge pressures and suction temperature, the results could damage the compressor and or driver. Nitrogen gets hotter than propane when compressed and it requires more work.