Q & A > Question Details
In our CCRU plant we have two net gas compressors which are discharging 38000 Nm3/ hr H2 gas (95 % H2 purity). Net gas compressors are two stage reciprocating compressors with recontacting section. We have 4500 Nm3/hr (87% H2 purity) of semi regenerative CRU off gas joining the circuit after the first stage discharge. We are facing problems with very high second stage suction strainer PDIs in our compressors (which is probably due to CRU off gas joining the circuit interstage). Recently we had conducted analysis of the muck we found on second stage suction valve plates.
The analysis is :
Sr.NO / Parameter / Unit
1 Moisture (@105ºC) % 5.4
2 Loss of Ignition at 800⁰C % 83.14
3 Ash at 800⁰C % 11.46
4 Solubility in water % 13
5 Oil Content % 16.96
6 Iron (Fe) as Fe2O3 % 8.716
7 Acid Insoluble ( ~ Silica etc) % 0.8
Can anyone provide further insights looking at these results?
22/04/2014 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Reciprocating compressors can be very sensitive to liquid and solid contaminants in the feed gas. With second stage compressor, there can be lube oil carryover from 1st stage of the compressor, plus also condensing liquids too due due compression. There may be some corrosion products/ scale coming with CRU offgas recycle as well. Is there ammonium salts there too? That's often an issue for reformers. Ammonium salts is a bigger problem for CCR's than for semi regen reformers but where this is high N2 in the feed, then ammonium salts are a pretty common cause for recycle gas compressor fouling and poor reliability. I have seen in some cases refineries have to clean suction strainers every 2 weeks.
A High efficiency Seprasol Liquid Gas coalescer can remove virtually all particulate matter and also virtually all liquids down to less than 0.011 ppmw.