Boiler discharging to a common steam main

Mon, 5 Apr 2021 18:09:35 GMT

Hi Mr. Rimbault,

What are the most important considerations when two or more boilers operate simultaneously and discharge into a common steam main?

Thank you

Thu, 8 Apr 2021 13:50:30 GMT

Thanks for the question Amina.

There is a very good explanation of this situation on the Spirax Sarco website titled "Steam Headers and Off Takes", which talks about the problems of connecting multiple running boilers into a common steam main. While the article suggests some ways of designing the header to minimise the problems, in most cases the boilers and steam header are arranged as below due to space or cost considerations.

The problems will occur when all the boilers are running on automatic control based on the steam pressure in each boiler. Hunting and unstable control will usually result as the boilers compete to deliver steam.

This situation can be avoided by only letting one boiler control itself automatically, and setting the others to run under fixed manual control. This arrangement will take a bit of time to establish the most suitable combination of boilers to match the steam demand, and this can only be done properly when steaming under normal circumstances.