12 replies to this topic

[shamir]

Dear Sir,

 

we are going to design a furnance in which there will be a exothermic reaction and from reator Phosphorous pentaoxide is release, temperature of Phosphorous pentaoxide is aroung 600 to 800 degree celcius..m.o.c of furnane( close jacketed furnance) is ss 316 

 Height of furnance is 10 mt x inner dia is 4 mt  x outer dia is 4.1 mt ( I.e jacketed is 100 mm ).having 4 nos of outer jacket at 2.5 mt each  .  Now i want to calculate heat load in a furnance for desiging of cooling tower load and flowrate. during process operation. furnnce temp will reach 1000 degree celcius. i want to cool 1000 degree celcius to 50 degree celcius,.

 

 

so please guide for calculation heat load in a furnace for proper design of cooling tower

 

Consideration :

 

Cooling water  temperature difference is 13 degree celcius.

 

questionre : is it right to calculate heat load by q= mcpt or by any other method.

 

Jacket

 approx Max Temp in ⁰C

Req Temp in ⁰C

Jacket 1

1200

50

Jacket 2

1200

50

Jacket 3

1400

50

Jacket 4

1200

50

Jacket 5

1200

50

jacketed line

800

50

bottom Plate

500

50

Edited by shamir, 12 June 2015 - 05:13 AM.

[mahmoud bedewy]

?

[shamir]

please any one can solve problem .I want to cool furnace all specification are given above. plese reply it is must

[thorium90]

If all you are going to do is calculate how much heat you need to remove, then yes, mass * heat capacity * temperature difference.

[samayaraj]

I feel the temperature difference between cooling water and reactor vessel is huge and gives much stress to the vessel. You did not mention the heat load (I hope it will be more) and how much it is?

 

You want to cool down the reactor temperature from 1200 Deg. C to 50 Deg. C all of the sudden??  Its like quenching. How much time is required to cool down the reactor?

 

You need enormous flow rate of cooling water to maintain 13 Deg. C temperature difference. Whether the jacket is designed to withstand the flow and area required for this huge temperature?

 

Heat exchanger design experts will help you more in this regard.

[thorium90]

Perhaps providing a simple PFD with some preliminary temperatures included will be more suited to comment on.

[shamir]

Jacket  approx Max Temp in ⁰C Req Temp in ⁰C Jacket 1 1200 50 Jacket 2 1200 50 Jacket 3 1400 50 Jacket 4 1200 50

 

Jacket is closed. jacket withstand pressure :1 kg/cm2

 

Please find the attached photo . 

 

QUESTION: 

What is the heat load accross chamber.

Attached Files

•  PFD BURNING CHAMBER.jpg   80.5KB   2 downloads

[shamir]

if any clarification required please send mail

 

[thorium90]

Your drawing is not quite understandable. It looks like you have some reactor with flames coming out the top of it and this reactor sits on the floor of a furnace. The furnace looks to be completely enclosed with no way in or out. Probably some kind of batch process whereby the reactants burn to completion inside a closed oven.

If that is the case, then you can just have a brick lined furnace, place the reactor bowl inside the oven, let the reaction complete itself, then remove the bowl and collect your product. It would be much like the process of making clay pots. You do not require any fancy liquid cooling jacket or cooling tower.

 

Anyhow, SS316 is not suitable as a material for directly facing high temperature flames. Your gas temperature might be 600-800C but the radiation would mean it would be alot higher. Your furnace should have a refractory facing the flames, not SS316...

Edited by thorium90, 25 July 2015 - 09:54 AM.

[shamir]

Thanks for reply,

 

 

[shamir]

Thanks for reply,

 

 

 in drawing i have not shown outlet but the top cone has outlet of 600 dia pipe and the generated Phosphorous pentaoxide gas generated during reaction in reactor goes to absorption system via Furnace.

 

Process is batch process.In addition we are already using brick furnace. During reaction phosphorous pentaoxide is generated in furnace and goes to absorption system via top duct from furnace.

There are two possibility for erosion of bricks

1.)Also due to batch process there is a thermal shock generation in furnace due to which bricks binding separate from each other and erosion start.

2.)As it is a batch process some phosphorous pentaoxide is converted in to phosphoric acid around ( 80 to 90% purity) and bricks erosion start simultaneously.

 

For that reason we are going to use SS 316 Burning chamber.( We have also read in literature about Thermal phosphric acid process in which ss 316 furnace is used .But difference is that they have control burning of phosphorous for food grade phosphoric acid plant but in our case there is no control reaciton as Excess phosphorous is burnt in reaction. ) 

 

I have calculated heat load in furnance but i am not sure of it . I have calculated it by Mcpt.

so please guide further for heat load calculations.

[shamir]

Dear thorium 90 please guide for calcualtions.

[thorium90]

I would think the maximum amount of heat that the cooling medium would need to remove would be equal to the heat of reaction generated.