Sliding Pressure and Industrial Boilers

It becomes unmanageable.

impact is danger to operator!!!

i want a elaborate reply

Read your books + you are not even authorized with this boiler or boiler room operations.First detail your authority and actaul job responsibilities.

Is it your pressure that is fluctuating due to a variable load requirement or is it a constant load? If it is a constant load application you and you are see that kind of change you may have a tube leaking. If it is a variable load system are you regulating your boiler with a PRV system?

We operate our supercritical unit on sliding pressure to alleviate stress/wear on the turbine throttle valves at lower power levels. A heat rate improvement is claimed at reduced power as well. We changed to sliding pressure once the market changed to where we are more cyclic/peaking instead of baseload. The unit controls well although I'm told there were a lot of growing pains and problems over the years.

We have one drum unit that we reduce throttle pressure (TP) at minimum load to improve governor valve stability.

I think the earlier comments (and our supercritical experience) allude to the idea that if the pressure setpoint is "slid" on a program with load, then fuel control would become quite cyclic with firing rate chasing TP, and governor valves chasing TP, etc.

Stepping TP at a load point (with plenty of deadband) will prevent this from happening. (As is on our drum unit).

All of our other units are constant TP.

Same with our Sub-critical units. We run in constant pressure mode when base loaded or normal (sinusoidal) load following conditions. Lately we've been cycling opposite of wind up to 25% of system load. Sliding pressure helps settle the boiler fuel/air, keeps flow & steam temps up and reduces turbine stress.

Thanks Dear !

I am new to designing field of Supercritical Boilers (Once through) as per MHI technology.

As per my understanding sliding pressure boilers are controlled by fluid flow and fuel flow as per load requirement, so there is no problem with changes in load from 30BMCR to 80 BMCR

Addingly if you can share me about HOT structure arrangement and guidelines for design it will be favor on my part i want to understand the load distribution of furnace draft, pulsation, seismic etc in practical way......waiting to here from you at sohebmujawar@gmail.com