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Heat Loss Through Pipe Insulation

pipe insullation heat transfer in insullation

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#1 Amol M

Amol M

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Posted 28 June 2017 - 01:28 AM

Dear All,


    I have installed three electrical heaters which gives outlet temperature 400 deg C each. Application of heater is to heat Air, NH3 and nitrogen up to 400 deg.

   Further heated vapors are entered in small mixer then further vapors goes in to column but I am getting 400 deg C temperature at outlet of heater but once it reaches to mixer, mixer inlet temperature is showing only 150 deg C.


From heater to mixer pipes length is 5 mtr each. and 125 mm insulation has used (75 mm glass wool+50 mm rock-wool).


I am not able to understand how and why this much heat loss is happening through insulation, even heater consultant is also not able to getting this issue. Kindly help me to solve this issue.


NOTE: This set up is pilot set.



Thanks & Regards,

Amol M

#2 Mahdi1980


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Posted 28 June 2017 - 03:45 AM


Please ensure that the temperature measuring element at the pipes outlet is calibrated and installed in the proper position ( at the core of the fluid through the pipe).

Otherwise, it is a strange event unless you have an enormous reduction in pressure. Do you have any pressure trouttle valve from heater to the mixer or any pressure drop there?

What are your working pressures at heater and mixer? How many pipelines do you have?

#3 Amol M

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Posted 29 June 2017 - 01:39 AM

Thank you for reply sir,


Total three heater are working independently but outlets of this heaters are connected to mixer. Heater to Mixer pipe length is 5 mtr each three lines for three heaters). Mixer is nothing but just horizontal vessel (dia 8" and length 0.4 mtr) which provides extra space to mix all vapors before it reaches to main column.


My one concern is, if vapors reaches to mixer there is sudden expansion so due to this is there any chances to temperature drop in mixer.?

#4 Waqar1989


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Posted 25 July 2017 - 12:41 PM

Assuming the temperature measurements are correct and pressure letdown is not significant, i would suggest checking mixer outlet gas composition to see if there is any change as compared to the inelt. If an endothermic reaction is going on, it can account for the sudden drop in temp. on mixing....

This is just a hypothesis...

#5 Waqar1989


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Posted 25 July 2017 - 12:44 PM

Also u may try swaping the temperature sensors to see if all sensors indicate 150 deg. C at mixer inlet.

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