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Redirecting flash steam in boiler feedtank

Redirecting flash steam in boiler feedtank

(OP)
Hello,

I have a PPPPU condensate pump which pumps hot condensate to a 3m3 Boiler feedtank. During its operation, some flash steam exits the exhaust pipe of the pump. I want to know if it is viable to redirect the flash steam inside the feedtank in order to recover the flash steam being lost and also what would be the most simple and best design. I was thinking of 2 possible options:

1. Redirect the flash steam inside the feedtank via sparge pipes which will be located at the bottom of the tank
2. Install a deaerator in the feedtank and connect the exhaust pipe to the deaerator inlet

Option 1 will involve few modifications and also is most simple one. But is this option viable?

For option 2, this will involve manufacturing/purchasing an appropriate deaerator. I will also need to redirect the cold make-up and return condensate pipelines to the deaerator and install a recirculation pipeline

Do you have any suggestions?


RE: Redirecting flash steam in boiler feedtank

Before you spend time assessing what can be done with this flash steam, determine the economic value of recovering this heat. Based on the size of this boiler feed water tank (3m^3) this appears to be a very small boiler. If so, the condensate flow rate is low, resulting in a small amount of flash steam. Small amounts of low pressure steam have very little economic value. For any project aimed at recovering this heat, you can only justify spending a very small amount of money, otherwise the project isn't economical.

RE: Redirecting flash steam in boiler feedtank

Hey Davkoo,

I just wanted to add another idea which I think is even easier and cheaper: consider recovering the heat from the liquid stream before flashing into the tank.

A pumped liquid stream will be easy to reroute compared to trying to recover the flash steam. You need only find a cold stream to pair your hot condensate with. If you get the temperature to 212F before "flashing", there will be no flash steam to lose, and your water will still be at boiling temperature.

good luck,
sshep

RE: Redirecting flash steam in boiler feedtank

Davkoo, is there only one unit creating condensate that returns to your condensate pump? If so a closed loop system (not vented to atmosphere) would than work. What is the distance between your steam trap and the inlet of the Condensate Pump Package ? That's the issue with getting those pre-packaged mechanical condensate systems. They are convenient, and in the case of that manufacturer you have, even economical. But they restrict your fill head and other options during installation.

I have solved a similar issue by increasing the condensate pipe diameter size from 1" to 4" and made it run longer around the basement before enter the condensate pump to allow the condensate to prematurely flash. This enabled us to avoid the need for a receiver tank and just went straight into the inlet of the mechanical condensate pump(not recommended).

Quote (sshep)

A pumped liquid stream will be easy to reroute compared to trying to recover the flash steam. You need only find a cold stream to pair your hot condensate with. If you get the temperature to 212F before "flashing", there will be no flash steam to lose, and your water will still be at boiling temperature.
Careful! Water hammer due to thermal shock. In saturated condensate pipes, even small amounts of flash steam take up a large volume. Those little steam bubbles will suddenly implode when in contact with the colder condensate. Similar to cavitation that occurs with electric condensate pumps. I would avoid.

« Rien ne se perd, rien ne se crée : tout se transforme ».
— Antoine Laurent de Lavoisier (1743-1794)

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