Reboiler Condensate Handling Utilizing a Cooler

[valvepuke]

I have been reading many threads on the subject of handling condensate from a reboiler. We are in discussions with our client and can't seem to come to any agreement. The problem is that my client's condensate return header operates at 90 degC and 1 bara. The condensate from our reboiler is at 152 degC and 5 bar. Anything we do to drop the pressure into the condensate return piping will result in excess flashing. Also, my client is concerned with any two phase flow coming out of the reboiler due to process conditions. Here is what we want to propose to the client.

We will control steam into the reboiler with a CV. Condensate from the reboiler will flow to a condensate pot. Condensate pot will have a level transmitter. Condensate will flow to a cooler where it will be cooled to around 70 degC. A control valve downstream of the cooler, controlled by the condensate pot level, will control flow of the cool condensate into the atmospheric pressure return header.

Using a cooler seems like a lot of extra effort but cooling water is available and I just don't know what else to do with a lot (15750 kg/hr) of hot condensate and still satisfy my client. Would love to just dump it overboard!! Also, the client doesn't like steam traps.

Any thoughts would be very welcome.

 

[25362]

Or it can be used to form usable steam by flashing the condensate at the lower steam pressure level.

 

[sshep]

From the sound of it, you have plenty of users at a level that could use the flash steam. If you put in a pump, you should just pump the whole thing hot back to BFW recovery and reduce steam use in the deaerator or boiler. It seems a waste to send good heat to CW, and the cooler will be a good candidate for scaling problems.

 

[valvepuke]

Unfortunately this installation is on an oil production ship called an FPSO and our client has not indicated any other use for the steam other than to provide us heat for our reboiler. I agree that in most cases flash steam can be utilized for other heating uses. They have really restricted what we can do with the hot condensate. Of course, true to project work, our budget did not account for some of the suprises we have encountered with this condensate situation.

 

[ash9144]

Could you increase your exchanger and maintain a small condensate level in the exchanger to allow for subcooling?