Steam valve control
Eastman manufactures chemicals, fibres and plastics materials for use in a wide range of products
The GE turbine, driving a 7.5 megawatt electric generator, operated on 1450 psig steam. The steam flow to the turbine was controlled by seven control valves mounted in the turbine’s steam chest and operated by individual cams mounted on a 2 inch diameter cam shaft. As the cam shaft rotated approximately 200º, the cams lift opened the 7 control valves in a sequence based on the position of each cam on the shaft.
The existing actuator on the turbine was a 10 inch diameter single acting, spring return hydraulic cylinder, operating off the 150 psig turbine lube oil system through a mechanical governor operated pilot valve.
Lacking the design data on the aging system, replacing or retrofitting the existing cylinder with similar technology would be expensive, if technically possible or feasible.
Eastman chose a direct replacement of the existing hydraulic cylinder with a linear actuator.
The customer's engineers chose a GSX60 with a 10 inch stroke. The configuration required a handwheel for manual operation, with the clevis mount rotated 90º to allow unfettered access to the handwheel.