Dear fellow PalmIngineers, our mill has TNB supply to our process main switchboard for the start up and standby power source. I was asked by my Chargeman what if the Turbine tripped and TNB supply happens to be unavailable? What shall the Boilerman do in this situation? Shall we purchase a standby genset as an additional standby source?
When asked, has this situation ever happened over the last 8 years of our mill processing, he said it has never happened before.
I am looking forward to your valuable experience for us to make a decision.
Thank you guys.
Hi Wee, I will go with that Steam Driven Feed pump which is more fail-safe. Thanks for sharing.
Dear Wesley, I will go with C.S.Tan's practical suggestion that you install a steam driven feed pump in your boiler for the following reasons:
As I see it, steam is the only available source of power to drive the feed pump when you have no electrical power from TNB or your own Main Switch Board (MSB) when your steam turbine trips or due to problems with your MSB. The caveat is you will have to ensure your steam driven prime mover is in good operating condition by running it everyday during boiler start up.
Installing a Diesel Generating Set, if hooked onto the MSB, you will face the same risk as mentioned in Item 1. Coupling a Diesel Engine directly to the Feed Pump will eliminate the risk mentioned in Item 1 but ensuring the Diesel Engine is available during emergency is difficult. Most times, the Diesel Engine may not start due to weak battery or due to neglect during the standby period. In this case, the utility of the Diesel Engine is limited to driving the feed pump only. And there is the cost of diesel to run the Generating Set.
The cost of installing and operating the Diesel Generating Set or Diesel Engine will been higher than the cost of installing and operating a steam driven feed pump.
Alternatively, you can opt continue to use your electrical feed pumps but make sure to introduce and carry out frequent drills for emergency shutdown of the boiler as suggested by C.S.Tan. I have checked with some very experienced boiler chargeman and they assured me that with the Main Seam Valve fully closed and the ID and FD Fan stopped, the water level in the boiler will not go below the second low level. You will have to confirm this at your installation.
Thanks for CS Tan’s sharing. Most of the new mills are not having Steam pump as a standby nowadays. I wish others could share their experiences what should be the emergency shut down protocol in this unlikely event of turbine tripping without a back up power source?
Back up power for boiler feed pump. Hi Wesley, regarding the mentioned issue, you have further highlighted the probability of happening is very slim. Nevertheless, you are still considering the back up for such eventuality. My view is as follow, 1) you can go for a unit of steam turbine driven feed pump and the steam consumed direct to BPR. This unit should be used at certain internal so as to ensure it is operational at all time. 2) Alternatively, you can go for a diesel gen-set for this purpose. However, given it’s possibility of happening, this gen-set is idling most of the time and when it is required to perform during “emergency” , some of it’s moving parts may have problems. Thanks.