4 replies to this topic

[chemdk]

Hi everybody,

In my current assignment, the process fluid is being heated by HE from -20 deg C to 60 deg C and sent to downstream users. In case of heating medium failure the required temperature could not be met. So tracing is to be provided to maintain the temp @ 60 deg C @ user inlet (500 m line).

I am stuck while doing heat loss calculation from insulated heat traced piping? My approach is as_

1) Use Fourier's eq. for heat loss from pipe. q= 2 pi *K*L / ln (Do/Di) * (Tfluid - Twall)
2) calculate outside heat transfer, Q= ho * A * (Twall - Tamb)
3) electrical heat duty addition

By 1+3-2, I am getting pipe wall temperature. I need to know the heated fluid temperature?

can anybody tell whether my approach is correct? and guide on calculating the fluid temp.

Any reference from the literature would be highly appreciated.

[breizh]

Hi ,
Consider this resource to support your query ;

http://www.thermon.c...computrace.aspx

Hope this helps

Breizh

[Technical Bard]

Tracing will never heat a flowing line. If you lose your heating medium, you will lose the temperature in the downstream equipment. Tracing can only maintain a temperature in a stagnant line.

The most temperature gain I have seen from tracing a flowing line is a couple of degrees, and that was with a thermal oil tracer at 380°C.

[processeng05]

 Che resources.xlsx   495.28KB   76 downloadsHey, I am working on something similar. We have hot emulsion (water and bitumen) at 176 C entering an 8" pipeline, 1000m long with 1" thick fibre glass insulation. The volumetric flowrate of emulsion is 500 cubic metres per hour. The ambient air temperature is -15 C and we want the emulsion to be cooled to 120 degrees when it exits the pipeline. The wind speed is 5m/s. I want to calculate the total heat  loss through the system and also the time that it would take for the emulsion to cool down to this desired temperature while exiting the pipeline. I have created this spreadsheet to calculate the heatloss. I calculated the heat transfer coefficient for convection from insulation to air and heat transfer coefficient from emulsion to pipe. Then I calculated the total resistance of the system to get the total heat loss. I have attached my work with this reply. Can someone be kind enough to check my work for me and tell me if there is something wrong. I have been stuck on this for a while now. Thanks a lot

[breizh]

Processeng05 .

 

Consider these  resources  to support your query

http://tierling.home.texas.net/PipeHeatLossShell.htm 

 

http://checalc.com/calc/inshoriz.html

 

Breizh

Edited by breizh, 22 March 2013 - 12:20 AM.