Compressor Discharge Temperature Control


Thread Starter

Richard George

I am currently involved in a project looking at re-wheeling a gas turbine driven centrifugal axial compressor. Cooling fans, which are to be
changed due to the increased heat load, control the compressor discharge temperature and are manually operated when required.The proposal is
to operate the cooler fans automatically under closed loop control using variable speed drives to drive the fan motors. The temperature is
to be maintained within a band of 10-30 Centigrade.
Does anyone have experience of this type of application specifically with regard to the control scheme selection, what to account for when
analysing the control loop, or any other practical guidance.

Girard Baham Jr.

By-pass valves is your answer
1)Close loop system: control main loop temp by-pass valve should maitain loop temp. Compressor discharge temp controls.

example :Degree 78F degree is set point
water less then 78F continue on in the closed loop.once pass 78F ,valve open to allow cooling tower water until water temp at 70F.
(Valve close again)
Delta T return water close loop system temp senor need to be install.At least 10 ft before enter in the plant.

Cooling tower
2)Valves on each cell of the cooling tower.
a)NC sump b)NO top of cooling tower
setpoint for tower cut in 78F
cut out at 72F.

Why?This allow you to control water flow to top of the tower are atthe sump of the tower.Temp in sump of the tower is less the 78F top is
close position and sump valve is open.Once reach 78F vavles return normal position.

example: 78 F low speed (VSD should run at 20%)78F-cooling tower fans
82F med 40%
85F 60% full load

example : Say you have 3 cell on cooling tower.
Break down of one cell, now this able you to take just the cell out of service(still Two cell on line).There are valves top and bottom at a
push of button able you shut down.Plant still you and run no down time.

PS Good Control "major part"

Thank you