Q & A > Question Details
We are using Compressor Type WS2/180-A1 for our Naphtha HydroTreating recycle gas compressor. During Wash water injection at the up stream of NHT reactor effluent separator, water is carrying over to the suction of Compressor. As a result of that compressor discharge, flow becomes low and load current also becomes low which suggests one of the load valve is not functioning due to dirt in water may have choked the load valve. After cleaning the load valve, flow and current becomes normal again. This problem is being faced recently when some salt has formed at the downstream of NHT reactor effluent which is dissolving with the wash water and carrying over to the suction of compressor. In addition, we are facing this problem after 3.5 years of plant life cycle. My question is whether it is happening only for dirt in water or load valve's diaphragm and O ring get old or spring has lost its tensile strength. Whether the Compressor type WS2/180-A1 is designed to handle some liquid or water as it is designed for recycle gas of NHT unit? FYI- 1. Wash water injection has been continuing in a regular interval of 15 days since the inception of plant start-up 2. Salt formation at the suction strainer is experiencing currently.

04/05/2017 A: Apoorv Gupta, IOCL Haldia, apoorv.work19@gmail.com
Please Check following things:
1.0 Whether make up H2 is pure or impure ex. CRU. If H2 ex. CRU is being used, please check the health of chloride guard.
2.0 Feed Chloride may be checked w.r.t design figure.
3.0 Circuit from separator to RGC is to be regularly drained for any accumulated water , if draining provision is there.
4.0 Demister Pad is to be replaced in every turnaround.
02/05/2017 A: Saidul Hasan, Super Petrochemical (Pvt.) Limited, hasanceps@yahoo.com
Next shutdown/Maintenance period you can check Naphtha Hydro-treating Separator demister mesh. May be you faced a problem related to improper gas liquid separation. Separator demister mesh may have some restriction/block.
I have a suggestion that you can inject wash water 30 minutes in everyday with rated 5 gpm. As per naphtha hydrotrator guideline " if your feed contain more than 100 PPM sulfure and more or less 1% olefins you need to run wash water everyday.
21/03/2017 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Water and ammonium salts are known to cause H2 recycle gas compressor reliability issues for NHT, DHTU and Hydrocracker Units. It is unlikely suction strainer will help much as these are very coarse so most of ammonium salts will likely pass through into compressor. Also suction strainer has no ability to remove water or hydrocarbon liquids.
Liquid & Ammonium salts carryover is particularly a problem for reciprocating compressors however centrifugal type compressors are also sensitive to salts, but less so to the water. But the water contains the salts also as ammonium salts are very soluble so the water should be removed prior to the recycle gas compressor and that means you may need a high efficiency Liquid Gas coalescer to remove water, any hydrocarbon liquids and the entrained salts also.
Pall Corp has much experience in providing SepraSol LG coalescers for NHT, HDS and Hydrocrackers to protect H2 recycle gas compressors from liquid and solid contaminants. if you are interested to know more, please email me directly.