heat exchanger and fouling problem

[radjabumbumbu]

we are using heat exchanger to cool the gas to a desired temperature. Sometimes temperature set point can not be reached because of the fouling in the heat exchanger. We use cold water for cooling. Is there anybody who knows how to get rid of the fouling in the exhanger without shutting down the plant? I will appreciate your help.

 

[ash9144]

Is fouling on the process or water side?
If water your water treatment provider can help with some on line descale processes. These are usually somewhat risky.
If process side you need to look at the type of scale and determine if you can dissolve/flush it out of the exchanger.
You can always try blowing with nitrogen, back flushing, steaming. Depends on your unit

 

[MJCronin]

bumbubumbu..

Are you trending the inlet/outlet temperatures on both the shell and tube side ? Sometimes (gross)fouling can be detected by slight changes in the pressure drop.

Which TEMA type of heat exchanger do you have ?

Do you have finned tubes on the gas side ?

Your only reasonable alternative may be to install a second redundant HX in parallel with the first and swap them over when cleaning is necessary.

-MJC

 

[EmmanuelTop]

Do not allow cooling water temperature to exceed 40C at the outlet of heat exchanger.

If fouling is on the process side, you can't do much with the existing exchanger. Check what are the causes of fouling and perform a hydraulic analysis. Sometimes it happens that wrong type of exchanger is selected for particular service.

Best regards,

http://antwrp.gsfc.nasa.gov/apod/astropix.html

 

[chief]

You can get a quick clean of your heat exchanger, if there is a back pressure on your cooling water discharge. Back- flush from the outlet to the inlet . Depends if your valves are configured right or if you have a suitable drain after the inlet valve.
You can also 'break'an inlet flange and flush back this way.

Offshore Engineering&Design

 

[gr2vessels]

radjabumbumbu,
Seems that your water is the culprit in the heat transfer operation. I imagine that the water outlet temperature is relative high, allowing for rapid deposits of calcium and other salts on the tubes, possible because of lack of treatment of the cooling water. The cooling water can be treated "on the run" if you are really desperate and the calcium could be dissolved with some relative harsh water treatment. However, it seems that you have operating problems, rather than exchanger design problems. Just remember, once you dissolved the salts deposits from your tubes, you have to remove them from the water somewhere downstream, otherwise you return the water to the hot tubes and the bad cycle starts again...Perhaps some blow-down equipment downstream of the exchanger...
Also, you did not provide sufficient details of you process and the equipment you are using. Trust us, nobody will try to steal your job and giving up details will only help you to solve the problems you have.
Now, if the fouling is on the gas side, you have not filtered the gas properly before attempting to cool it down, hence you need some sort of knock-out drum up-stream of the cooler to separate as much as possible of the suspended contaminants and send only the clean gas to the heat exchanger for cooling.
Regards, gr2vessels