HRSG Superheater Drains

[blacklabs]

Is it acceptable to use steam flow through a superheater to remove condensate that may accumulate in the S/H? Some feel that a bottled up boiler with a couple hundred pounds of pressure will quickly remove condensate when steam flow is established when the vent is opened during startup. I feel any condensate should be removed via drains to prevent uneven heating or cold spots. Any comments?
Thanks in advance for any responses.

 

[PatBethea]

Use the drains - that's what they're there for.

 

[davefitz]

I assume you are talking about removing condensate during an outage, and also during startups.

Europeans use steam traps during outages, to minmize loss of steam.

During startups, there can be installed a condensate blowdown pot / trap with level control or conductivity probe for control of condensate level, or you can use the Siemens logic wihc is based on thermocouples in the drain line, and keep the drain valve open until the drain line t/c reads at least ( 40 F) above saturation temp.

 

[toothless]

Absolutely open the drains during a S/U, especially if you have an HRSG. The accumulated water can hammer or cause cause temperature gradients that create huge thermal stresses.

 

[blacklabs]

Thanks!