11 replies to this topic

[vijji]

Hi friends,
Any body guide / suggest me to improve the performance / efficiency of condenser / heat exchanger for pharmaceutical industry applications. Please help me in check list / parameters to be monitored while distillation of methanol under atmospherically..

[S.R.Shah]

Dsreenivasreddy:

Will you please give your present conditions?

• Present shell and tube heat exchanger configuration;
• Coolant flow and temperatures;
• methanol vapor flow.

These data can enable us to give you any steps for improving present conditions.

SRShah

[breizh]

Hi ,
A sketch or simple PId as mass and heat balances (as suggested) will help to support your query ! Please let us know your problem .

Breizh

[vijji]

Condenser size: 16 m2, Methanol vapor inlet temperature: 59 Deg.C condensate oulet temperature: 42 Deg.C, utility inlet temperature: 27 Deg.C and outlet temperature:31 Deg.C.

After 6 months the same was vapor inlet temperature: 59 Deg.C and condensate outlet temperature:50 Deg.C utility inlet temperaure: 27 Deg.C and outlet teperature: 29 Deg.C

If i calculate overall heat transfer coefficient for both the cases and shall i consider the performance / efficiency of heat exchnager decreased to ......%.

Edited by dsreenivasareddy123, 27 August 2012 - 10:52 AM.

[Shivshankar]

Reddy,

Hope attached documents helps you.

Regards
Shivshankar

Attached Files

•  4.4.Heat exchanger.pdf   330.94KB   3326 downloads
•  4.4_Heat_exchangers.pdf   115.76KB   2560 downloads

[Robert Montoya]

Dear dsreenivasareddy123, if you want to evaluate a heat exchanger in order to improve it´s performance you should use a simulator as: HEXTRAN or HTRI.
Compare the fouling design with the actual conditions. The fouling indicates that both have decreased the heat transfer area calculated with respect to design or actual area. You can compare during 15 days the fouling, request that the flow should be the design flow and enter to simulation the temperature, pressure an flow for both sides (cold and hot) once that you validated the design model.

Sometimes is valid to compare UA in normal operating with design but the final decision is compare the heat transfer area.

Edited by Robert Montoya, 11 October 2012 - 10:17 PM.

[breizh]

Hi ,
Calculation is one thing but we need basic data like flow rate ( at least on the coolant ) today versus spec sheet , the nature of the material ( any change in the composition) .Any risk to have air pocket which may affect the heat transfer as fouling will do .....

Again more input is needed including a sketch

Breizh

[T.S.MURALI]

The considerations are U which takes care of FF on both streams; lmtd & Stream flows/load.

Other operational aspect , of course is cleaning of T&S.

A simulation exercise with a simple or an appropriate software will reveal!

And one should see the Delta P as well.

[srfish]

Vijji

That is a big decrease in performance in 6 months. That means the heat load is 1/2 of what it was at the beginning. Is this a new heat exchanger or do you have older performance data? If so does the performance degrade this much each 6 months period?

[S.AHMAD]

1. Performance analysis of condenser is a complex subject this is due to the fact that condeser performance can be divided into three or two parts that is pre-cooling followed by condensing and then by super-cooling. If the inlet vapor is saturated, in your case the methanol is condensed at 59C and supercooled to 49C etc. Therefore, calculation of fouling factor requires iteration.
2. The simplest indicative method is by comparing the heat duty based on the cooling medium by assuming the cooling medium flowrate unchanged and specific heat is also unchange. For cooling water for example the ratio of heat duty before anf after is the same as the ratio of temperature difference. Therefore the efficiency in your case:

Eff = (29 - 27)/(31 - 27)*100 = 2/4*100 = 50%

You may use the design temperature difference as your basis for monitoring the ternd of the condenser performance. However, if the cooling water flowrate is not the same as the actual, you need to make necessary adjustment/correction.

Edited by S.AHMAD, 29 October 2012 - 09:29 PM.

[S.R.Shah]

Vijji;

Please furnish Condensed Methanol Mass Flow Rate in both the cases

SRShah.

[mvp]

Cooling water on shell side or tube side?
What is the flow rate / velocity?
I hope the Cooling water is NOT being throttled
I suspect fouling due to cooling water.
If you can provide more information, like geometry, flow rates, cooling water treatment method, you will get a lot more help in trouble shooting from this forum