A test was run on a GE frame 7 gas turbine. The test was to see if running both oil coolers in parallel would help with efficiency. The test showed that running both oil coolers in parallel actually lowers the efficiency.

Is there is easy explanation as to why this happened?

 

The L.O. Coolers of GE-design heavy duty gas turbines are not designed to be run in parallel. The <b>Transfer Valve</b> is not designed to be operated in mid-position. In fact, usually when it's left in mid-position for some period of time the o-rings used to seal the coolers from one another get dislodged and when the valve is moved to one side or the other the o-rings for both sides get cut and then neither cooler can be fully isolated during operation (there will be some "leakage" through the Transfer Valve if the o-rings are damaged).

The Transfer Valve does allow for switching from one cooler to the other while the unit is running but it is not designed for parallel operation. I believe the flow to both coolers is somewhat restricted in mid-position, not sufficiently restricted that it will cause problems during a change-over which should only take a minute or so to accomplish.

The instruction manuals provided with the turbine should have information about the Transfer Valve in them. Or, you may be able to find information on the World Wide Web if you know the manufacturer and model number.

If the Transfer Valve is working properly, I believe it is possible to remove one cooler bundle while the unit is running on the other cooler bundle, so the removed cooler bundle and its shell can be cleaned and re-assembled. Sometimes, the piping in front of the coolers doesn't permit this, but I believe that's supposed to be the intent of the system.

 

> The L.O. Coolers of GE-design heavy duty gas turbines are not designed to be
> run in parallel. The <b>Transfer Valve</b> is not designed to be operated in mid-position.

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> Sometimes, the piping in front of the coolers doesn't permit this, but I
> believe that's supposed to be the intent of the system.

Extremely helpful! Thank you!!!