Q & A > Question Details
I would like to hear your views on the factors that are the major causes of the increase in Wheel Chamber Pressure. To give you a background, we are currently experiencing an uptrend of wheel chamber pressure on our MANTURBO turbine almost reaching alarm values. Turbine steam flow has slightly increased also. Adjustment of exhaust pressure has yield into a slight decrease of WCP.
Base on our findings, we are leaning into fouling as one of probable causes of the increase of wheel chamber pressure. However, there was no axial movement of rotor or increase of bearing temp on the active side of the thrust bearing. Does increase of wheel chamber pressure always equates to movement of rotor and increase of bearing temp?
Furthermore, we cannot explain the observed trend of the WCP. Every time we reduce the feed rate, WCP also decreases. However we cannot explain why when we increase feed rate to its value prior reduction, (Ex. from 35 mbsd, to 25mbsd then return to 35 mbsd again) Wheel chamber pressure will be higher and have an uptrend increase! What do you think is the explanation with this observe trend?
As of the moment, we cannot afford to down the equipment and we do not have the necessary materials for overhauling. Can you guys share your thoughts on how can we lower the WCP? Or even just maintain pressure and prevent any further increase?
18/02/2019 A: keith bowers, B and B Consulting, kebowers47@gmail.com
First thing is to verify accuracy and precision of the Pressure and temperature indicators. I am presuming you are discussion steam turbine and not process gas compressor. You understand steam side fouling will increase the water rate and chamber pressure to deliver the WORK required by the process gas compressor. With no indication of rotor drift or imbalance, one can presume internal fouling is the root cause of the efficiency loss.
Many times an on-line cleaning will extend the run length before shutdown for cleaning is necessary. I suggest contacting the tech folks of the manufacturer and discuss upper limits of allowable operating chamber pressures. There may be a significant allowance ('safety margin') built into the 'alarm values.
For process gas compressor, on-line washing is often used to clean the compressor internals and extend the run-lengths.
Any changes (up or down) in WORK requirements will disturb the fouling deposit distribution and may cause an increase, or decrease in fouling in the pressure drop critical location. This is specific to each machine and the operating conditions and not amenable to generalized prediction.