Here's a good one

I have two "identical" Howden WRV 255 units, running side by side on the same plant.

one has a maag NP 70/70 oilpump and the other has a Viking oil pump.

One has a Danfoss ORV oil mixing valve I suspect has a 48C thermostat, the other has a aamot mixing valve and I think the mixing thermostat is 42C

the one with the maag pump is running with an oil temperature of 52C, discharge of 98,7C.

The one with the viking is running with an oil temperature of 43C and a discharge of 84C.

The problem was that the one with the maag pump would slowly loose oil pressure while it was running in 100% load, and as the pressure dropped, the discharge temp would rise.

I have tightened the spring on the internal safety valve on the maag oil pump but no luck, I closed the external pressure relief, still no change.

The howden WRV has oil injection valves used to regulate the oil flow into the rotors, used to cool the discharge gas, I fine tuned these, by closing them until the discharge temp started rising more and then opening them again until the discharge temp stabilized, then fine tuning by opening a 1/4 turn and watched as the discharge temp dropped, hen opened another 1/4 turn and so on until the oil pressure started dropping, figuring I had reached equilibrium and could not adjust more

The last thing I did was to close the economizer, and the oil pressure rose .6 bar from 1,4 to 2.1 bar in 3 minutes or so.

I have noticed in similar plants that a 1 Kelvin rise in OT would result in a 2-3 Kelvin rise in discharge temp, so I have ordered a new 42C thermostat for the ORV.

My thinking is that lowering the OT 10 kelvin will give me a 15-20 kelvin drop in the discharge temp.

What has me stumped is why closing the economizer gave me a better oil pressure?
the economizer pressure was -30C (0,2 bar), and if anything, it should help cool the discharge, or am I wrong?


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Also, on googling the subject, my boss came up with a thread from RE about LRI injection vs economizer, where I was heavily involved (baiting ), and he showed it to me and said, "see, it says right here" I didn't have the heart to tell him I had written the text he showed me