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Gas cooling

Gas cooling

Gas cooling

I am about to use a laboratory furnace which will heat up to 600 C. Gases will be generated and these will need to be cool down till 25-30 C.
Can someone please advise on the best way to do it. Some people recommended me in the past a stainless steel coil in built in a water circuit. Dimensions is another important thing to consider.

RE: Gas cooling

What are the dimensions to consider? What gases? What constraints do you have?
Your questions is very vague right now, please provide more details.

RE: Gas cooling

What types of gases?

What is driving your end requirement of 30°C? Your HVAC ducting? You may not be able to use those anyways, depending on the types of gases you're using.

RE: Gas cooling

Volatile organic compounds will be generated inside a furnace and using a flow of clean air going through the furnace(2L/min). The mix of gases (unknown) coming out the furnace at high temperature (300 C and higher) will need to be cooled down to 25 C in order to get these gases passing into gas sensors (temperature limit of 25-30 C). I am in the stage of figuring out the length of coil needed or whether this is feasible, by means of calculating the heat exchange between the water and the gas (considering pure air, as I don't know which volatiles will be generated).
Any suggestions?

RE: Gas cooling

I don't have any experience with equipment on such a small scale as this, but I suggest you start off by cooling with air instead of water. I'm assuming this is probably indoors, in an air conditioned environment. Although your temperature is extremely high, the heat duty required to cool this small volume of gas is low. Consider blowing cool air across a coil of small diameter tubing. To get down to 25-30C you'll probably need to route the stream through another coil of tubing that's immersed in water.

RE: Gas cooling

You'll need to read up on natural convection and forced convection modes of heat transfer from any basic heat transfer text. Forced convection for generating the inside htc, and natural convection for generating the outside htc with water or air. But you need to know the inlet temp with some degree of accuracy (300degC?). Also a rough idea of the pressure in the coils as the gas flow through these and the gas analysers befor it is vented (to atmosphere?), so you can work out what is a reasonable overall pressure drop.

Agreed, an initial cooling with air would help to avoid boiling of water on the tube OD if you were to use plain tubing, else you may consider finned tubing for faster cooling with lower OD metal temps if want to use only water.

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