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Partial Heating Of The Tank

heating tank

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#1 kreshnik

kreshnik

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Posted 03 August 2016 - 01:53 AM

Dear all,

 

I'm currently working on a project of heating a 8.000 cbm tank that contains oil palm. There is available a steam boiler with capacity 1750 kw, working pressure 6 bar and "F&A 2400 kg/h".

 

The request from the client is:

 - The difference of the temperature after heating shall be from 5oC to 30oC.

 - The tank shall not be insulated.

 - The quantity needed is 300 cbm per week.

 

According to my calculations, all the loses from the tank will be 1.526 kw that means with the available steam boiler it will take 390 hours to heat the total mass. This will be something unacceptable!

 

Now, considering that they will need 300 cbm per week, I'm proposing to construct inside the tank a preheating chamber with a volume appx 100cbm with only one side opened, to concentrate all heating coils inside this chamber and to speed up the heating process only for this part of the tank. (please see the picture in attach)

Doing this, I will not need to heat the whole quantity in the tank before starting to take the product, and in 1 hour the mass (100 cbm) will be ready with a temp appx 30oC.

 

Can somebody give an opinion for this solution? Can it work in this way?

 

I will appreciate your feedback.

Best Regards,

Kreshnik

 

Attached Thumbnails

  • Serpentina - 8000 -2-Model.png


#2 samayaraj

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Posted 03 August 2016 - 03:01 AM

Hi Kreshnik,

 

This wont work. Since the heating medium is in the bottom, the heated up liquid will set a convection inside the tank with cold liquids due to density difference. Hence you cannot heat the required amount of liquid.

 

Its better to install the preheating tank outside main tank.



#3 cea

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Posted 03 August 2016 - 04:19 AM

Barring your scheme, I am little confused with your calculation.

 

Let me reconcile your data as below -

 

Tank capacity (Operating) - 8000 m3

Temperature of containment to be raised from 5ºC - 30ºC

 

Estimated heat loss - 1.526 kW (1315 kCal/hr)

Heating fluid - 6 barg saturated steam (Latent heat 493 kCal/kg)

 

Now, as Samayaraj has rightly said, your proposed scheme will not work, as you have ignored convection effect within tank. Your scheme can be implemented by installing "in line heater" in exit loop. You cannot install coil chamber within tank & expect it to work like separate heater tank / inline heater.

 

Now coming to your calculation part.

As you said, heat loss through tank is 1.526kW which is about 1315 kCal/hr. Now, estimate heat duty required to heat containment within one hour. Let us say, it is in range of 210 x 10^6 kCal (Please confirm)

 

Considering saturated steam at 6 barg pressure, latent heat is expected to be 493 kCal/kg.

Thus amount of steam required is estimated to be = 426000 kg/hr.

 

With available boiler capacity of 2400 kg/hr, time required will be ~180 hrs.

 

Thus, initially you may have to start heating one week ahead of transfer. However, once temperature is reached to 30ºC, you need to just take care of heat loss to maintain temperature, which can be compensated by passing very small steam flow (~5 kg/hr) continuously through coil.

 

I feel, this is most optimum scheme & industry wise standard one.






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