5 replies to this topic

[jui]

I need to cool the liquid stream containing di butyl pthalate with trace amount of water and maleic anhydride from 240 to 100 degree celsius.

Is it okay if i use water at 30 degrees for the same and keep it in the tubes?

Will the water come out as steam at 100 degree celsius after cooling the liquid process stream?

If not water,what else can be used?

P.S. dibutyl pthalate is non corrosive and the tubes and shell side pressures are 1 atm.

 

[aroon]

Jui,

 

Firstly I would like to ask you few questions,

1. Is this application is in actual plant or laboratory use? Because I never saw cooling water at 1 atm pressure in plant scale if it is absolute scale.
2. If the application is in plant, then what is the maximum permissible cooling water return temperature as per utility design basis? Generally, 10°C delta T is considered in normal practice so your water will not evaporate during normal operation as your cooling water return temperature should be 40°C or maximum up to 45°C. Based on this you will have to calculate the cooling water requirement.
3. If it is in the actual plant, why you are not trying for the possible option of heat integration? Your process stream is having potential to provide heat input to any of the system.

 

I would say ...... Tube side is OK for cooling water, Water will not vaporize in normal case (However, effect of vaporization should be considered during cold side blocked-in contingency), You may try for any available cold process stream for energy augmentation.

[srfish]

Be sure and check the tube wall temperature on the cooling water side. If it is too hot there could be Calcium Carbonate deposits. For more information refer to www.gulleyassociates.com and in the engineering tips section search for "Check for hot tube  wall temperature of cooling water".

[jui]

Aroon,

Im trying to design the heat exchanger as a part of my B.E. project and it is supposed to be a on a plant scale.
And i did the cooling by heat integration instead of water,thanks.

[xavio]

jui,

 

I agree with aroon, if you want to use water as cooling medium, it should be pressurized water, 4-5 bara typical.

So, you will not get any vaporization when it indeed rises to 100C.

What you will get is the problem mentioned by srfish.

Besides, why would you let it rise to 100C anyway? You can adjust the water flowrate so that outlet temp is not too high.

 

Back to your particular problem, reducing temp from 240C to 100C is a tough job for a heat exchanger, you may need a few in series.

There will also be mechanical stress problem due to such a high temp difference.

If you use 30C water as cooling medium, I think the stress problem as well as the problem mentioned by srfish will be severe.

 

You said you have done heat integration on this unit, I suppose you have considered all the potential problems.

 

Good luck!

 

xavio

[Padmakar Katre]

Aroon,

Im trying to design the heat exchanger as a part of my B.E. project and it is supposed to be a on a plant scale.
And i did the cooling by heat integration instead of water,thanks.

 

Hi,

Since it is academic, I am not sure if your professor will pose questions like issue of using cooling water at such high process side inlet temperature. As mentioned by forum members that you have to monitor the tube wall temperatures for possible issue of fouling. Alternate option is to use an air cooler rather than cooling water exchanger. Use of air cooler for cooling process stream 240 to 100 deg is best choice if heat integration is not possible (no user available at receiving end). Process side outlet  temperature of 100 deg C itself is very high and will ensure tube wall temperature will be beyond allowable limits irrespective cooling water velocity, film coefficients.