5 replies to this topic

[Padmakar Katre]

Dear Friends,
I am enclosing the Excel Spreadsheet which contains the boiler feed water required for the desuperheaters I hope this will be helpful.

[Art Montemayor]

Padmakar:

Your attachment spreadsheet did not make it into the posting.

Maybe you did not follow the correct procedure for uploading an attachment. The Forum doesn't offer any "friendly" instructions, so you have to practice at it.

Tell us if you need help in uploading.

[Padmakar Katre]

I am sorry I think I did mistake now I will upload it.

Attached Files

•  DESUPERHEATER_BOILER_FEED_WATER_REQUIREMENT.xls   19.5KB   682 downloads

[chau]

I am sorry I think I did mistake now I will upload it.

Hello Mr Padmakar

Your spread sheet , seems you hav eduly focused on getting the saturated steam out of boiler. But one thing which iam vague about , why it is required to bring the superheated steam to saturated steam out of the boiler. I conceive the superheated steam will have more adventagous by accounting of more enthalpy addition and hence more power generation. Our boiler vendor are using the desuperheater after the superheater , though i intend of their application , as perhabs to be used to configure and maintaining the superheated steam up to its boundary level

Awaiting for your reply

[Padmakar Katre]

Dear,
Let me clear you first thing that Desuperheater is not a part of any boiler. Desuperheater comes in the PRDS (Pressure Reduction and Desuperheating Section). The requirement of this section depends upon the type of boiler generated steam (saturated or Superheated), the users (based on the inlet pressure). When you have superheated steam coming from the boiler you can't use it in reboilers so you need to have saturated steam and you get it by injecting the boiler feed water into the superheated steam in a device called Desuperheater. Actullay in process plants there are different steam users at different pressure levels now when you let down the steam from a higher pressure to the required pressure/s (if steam grid consist of diff pressure steam headers) due to an adiabatic expansion across the pressure let down valve you will find the degree of superheat which we have to remove befor the steam would be used in reboilers. Here the need comes of injection of boiler feed water.
Reply to your second doubt is that in any boiler there is no any desuperheater but an attemptator which controls the superheater outlet temperature of the steam. The steam generated in boiler steam drum (heated in mud drum) will be the saturated steam which will go to superheater (part/section of boiler) to make the steam superheated. Here the outlet steam temperature is controlled by the injection of BFW in an attemptator (and not a desuperheater).
I hope this will clear your doubt.

[cmp74]

excellent reply .....Padmakar.

I would also like to add that many times turbine drives exhaust steam will be at a pressure higher then next lower Pressure level in plant.So you have to letdown this stream and also desuperheat as you mentioned....

C.