Our Plant consists of Two GE Frame-9E GTs, Two Vertical HRSGs (Manufacturer: HBG, China) one Steam Turbine (HTC, China).
GT Rated Capacity: 115MW @ site conditions; 1013 mbarg, 32 degC, 85%RH
HRSG Rating: HP Steam -75.6 barg/505 degC/182.9 t/hr
LP Steam-6.3 barg/259.4 degC/36.8 t/hr
Steam Turbine Rating: 123 MW.
As per HRSG manufacturer guideline during cold start of the plant we usually open diverter damper step by step starting from 20% to 100%/ to control the HRSG HP drum metal temperature difference (between upper half & lower half) within the limit (<41 degC). It also takes 1~2 hours to start HRSG from cold condition, and during start up, GT load hold at 6~8MW or at FSNL when GT Exhaust Flue gas temperature is 300~310 degC.
With this type of start up method we have faced problem in our Diverter Damper. i.e. generated crack on diverter damper shaft, deformation of diverter damper casing, etc. So we called our HRSG manufacturer for investigating the problem. After investigation they have suggested to operate diverter damper full open or full close for any kind of operation. (At full open or full close position diverter damper cooling & sealing system is active & useful. At D/D intermediate position it is useless.)
Our plant need to start 7~12 times in cold condition due to off taker load demand.
Noted that during start up of HRSG, we maintained min drum level as per OEM recommendation. We tried to start HRSG in D/D full open condition, but the upper & lower metal temperature difference of HP drum could not maintain within limit. Now its a great problem for us to start the plant in cold condition.
My query is that how we can overcome the problem of cold start up? Anybody have any experience please share.
GT Rated Capacity: 115MW @ site conditions; 1013 mbarg, 32 degC, 85%RH
HRSG Rating: HP Steam -75.6 barg/505 degC/182.9 t/hr
LP Steam-6.3 barg/259.4 degC/36.8 t/hr
Steam Turbine Rating: 123 MW.
As per HRSG manufacturer guideline during cold start of the plant we usually open diverter damper step by step starting from 20% to 100%/ to control the HRSG HP drum metal temperature difference (between upper half & lower half) within the limit (<41 degC). It also takes 1~2 hours to start HRSG from cold condition, and during start up, GT load hold at 6~8MW or at FSNL when GT Exhaust Flue gas temperature is 300~310 degC.
With this type of start up method we have faced problem in our Diverter Damper. i.e. generated crack on diverter damper shaft, deformation of diverter damper casing, etc. So we called our HRSG manufacturer for investigating the problem. After investigation they have suggested to operate diverter damper full open or full close for any kind of operation. (At full open or full close position diverter damper cooling & sealing system is active & useful. At D/D intermediate position it is useless.)
Our plant need to start 7~12 times in cold condition due to off taker load demand.
Noted that during start up of HRSG, we maintained min drum level as per OEM recommendation. We tried to start HRSG in D/D full open condition, but the upper & lower metal temperature difference of HP drum could not maintain within limit. Now its a great problem for us to start the plant in cold condition.
My query is that how we can overcome the problem of cold start up? Anybody have any experience please share.