6 replies to this topic

[anjan.paul]

Hi Guys,

 

I am transfering 1,3 butadiene from storage tank to reactor. after 1 batch 1,3 BD will be stagnant in pipe for for batch i.e for 7 hr. i just need to find out the heat gain as well as temp of fluid after 7 hr. On that basis we will decide that we will provide chilled water jacket or not.

 

data:

 

pipe size= 100NB

insulation thk= 75 mm

pipe length = 300 m

specific heat= 0.52 KCAL/KG-C

density= 625 kg/m3

insulation conductivity= 0.04 w/m2-k

1,3 BD initial temp= 15 degree C

 

 

Regards,

Anjan Paul

 

[thorium90]

Your ambient temperature is not specified.

 

Anyway, this is a transient heat transfer problem. Explanation's in the link

 

http://www.google.co....48340889,d.bmk

Attached Thumbnails

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[anjan.paul]

consider ambient temp= 40 degree C

 

Can anyone share with me excel calculation file regarding the above problem

[Pingue2008]

anjan.paul,

 

This thread was discussed a while back and someone submitted a spreadsheet. use the search engine. I am not quite clear as to what is going on .

your fluid stop flowing for 7h and you need to know the heat gain/loss? if this is the case, you have a storage tank situation. if not; provide the following for the fluid Flow rate, Viscosity and thermal conductivity and also provide the thermal conductivity of your pipe and emittance. I thought I had that spreadsheet saved.

 

Thank you,

 

[thorium90]

The spreadsheet by steve hall was for heat loss in a flowing medium in a pipe not for a stagnant fluid. Although the calculations above also doesnt take into account pressure increase due to vaporization. Then again, why is it necessary to do this? Why cant one drain the pipe when it is not in use for the 7hrs rather than buy and install a chilling mechanism? It is a mere 300m and the pipe is not that huge either and 7hrs is a relatively long time.

Also, the solution for a finite cylinder (tank) versus infinite cylinder (pipe) is different. The thermal conductivity of the insulation was also given.

Edited by thorium90, 27 June 2013 - 10:12 AM.

[anjan.paul]

draining of 1,3 butadiene is a loss for client. yes we can provide chilled water jacketed pipe. But we are trying to find out whether only insulation is sufficient or not.initial temp of 1,3 BD is 15 degree C & we can allow temp upto 20 degree C after 8 hr. 

 

Anyway we cant use spread sheet given by steve because that sheet was for steady state flow not for stagnant fluid.

 

I think it is clear to all now. 

 

can anyone guide me for calculating heat gain & temp rise for my case.

[thorium90]

The attachment explained how to non dimensionalize your equation, then use the chart to find the temperature wrt to time... It should'nt be too hard to understand since this is just undergraduate heat transfer. Use the infinite cylinder. If you cant see clearly the picture, the dimensionless temperature is:

 

(T - T_Bulk) / (T_i - T_Bulk)

 

Also, 1,3 butadiene has a normal boiling point of -4.4C. Is it possible to drain back into its own storage tank?

Edited by thorium90, 27 June 2013 - 10:24 AM.