Spiral Heat exchangers: We have sp 1

[aberta]

Spiral Heat exchangers:
We have spiral heat exchangers that cool flushing liquor which contains tar and other by products of coke oven gas. The flushing liquor (recirculated) is used to cool coke oven gas and itself is cooled by water. The liquor is the gas condensate. We experience fouling on water side as well as liquor side. Has anyone come across cleaning this type of heatexchanger or similar, using compressed gas(nitrogen) while the system is online. The nitrogen will be injected into both streams.
Thanks.

 

[Montemayor]

aberta:

You fail to tell us the TYPE of spiral heat exchanger you are using: is it totally enclosed plates(welded)? or is it of the open plate type? If it is of the open type (typically used in slurries and heavy, viscous applications), then you have no problem in opening the front or back cover and manually cleaning it. If your unit is entirely closed or welded, you're up the proverbial creek without a paddle.

I seriously doubt that you can effect any type of cleanout by using injected gases or Nitrogen into the liquid fluids being circulated. Just what type of effect do you expect to get out of the injected Nitrogen? In order to cleanout any type of process equipement -especially heat exchangers- you have to rely on a chemical or mechanical action. In your proposed method I don't believe you will have either. Normally what is done is that the fouling (or dirty) substance is identified and a suitable solvent or chemical reactant is selected to either:

1) Dissolve the fouling agent and flush out the resulting solution; or,
2) React the fouling agent with an acid or basic chemical and flush out the resultant , soluble product.

Either way, you're going to have to shut down the exchangers to carry out the above methods. If you resort to mechanical cleanout, you will also have to shut down the units. I believe I know what you are trying to do: stay on stream with the units while you clean them out with a "magical additive". I have never seen or heard of this working in my 43 years as a professional engineer. Good luck.


Art Montemayor
Spring, TX

 

[aberta]

Montemayor:

Thanks for your comments.
Our spiral heat exchangers are the open type, and we do resolve to acid cleaning them as you rightly mentioned. After acid cleaning, the heat exchanger works very well. I am looking for that magical solution (you guessed), if it exists...apparently not per your comments. It has been suggested in one of our technical reports of 1985 that blowing compressed nitrogen at 80 psi may dislodge sludge and also scale on the water side. I would expect the HX will shake and knock as the gas finds its way through the spirals of the HX. I have no data to prove it, and am looking for someone elses experience.