effect of boiler feed water temperature on main steam temperature

[pradeep4u]

Dear All
In once through boilers why low boiler feed water temperature leads to reduced superheated steam temperature.
Regards
Pradeep

 

[MJCronin]

Uuummmm.... because the boiler can only add so much energy to the feedwater ???!!!!

MJCronin
Sr. Process Engineer

 

[hacksaw]

Like the above post, the boiler is designed for specific feedwater temps and steam production, it gets vastly more complicated beyond that.

 

[davefitz]

IN a OTU , the ratio of firing rate to feedwater flow ( FR/FW) is supposed to be adjusted ( perturbed) so that the main steam outlet temperature achieves the desired setpoint, so the stated issue should never exist.

In a drum type boiler, a low feedwater temperature will lead to a higher final steam temperature and a lower steam flowrate.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[crshears]

In once through boilers why low boiler feed water temperature leads to reduced superheated steam temperature

To expand on MJCronin's reponse: This will only be true if the fuel input has not been increased to compensate for the lower feed water supply temperature.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[Dhurjati Sen]

Dear Pradeep,

Are you referring to process boilers? Then the answer lies in the process parameters, plant design, the FEED even.

Regards.

DHURJATI SEN