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hot air generator

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AHMEDDODO

Mechanical
Apr 4, 2006
9
iam working in a vacum salt plant and we need to generate hot air through multi stage heat exchanger between air from a blower and heat from direct flame using a burner
i want to decide what burner i should use so i need to know how i can calculate the heat needed to heat 154 metre cubic per minute of air from 25 degree to 150 degree at normal pressure

tanks
 
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I don't know what you're process is, but whatever you're doing you are adding a lot of BTU's to a lot of air. Rather than using a blower and a heat exchanger you might be able to use a single-stage recip to take atmospheric air to about 2.8 barg (3.4 compression ratios, heat of compression is about 150C)and then exhaust it into your process. That is a 450 kW compressor which would probably cost more than your blower/heat exchanger combination, but might be lower fuel costs and lower life-cycle costs.

Just an idea.

David
 
Ahmeddodo,

First you need to convert the volume flow to a mass flow (lb/hr or Kg/hr). In metric units the density should be on the order of 1.2 kg/m^3. The actual density may be slightly more or less than this, depending on what temperature you use for the volume flow.

The specific heat of are is approx. .24 Kcal/(Kg-Deg C)

Now you can simply multiply the the three factors together to get the heat load:

Q = M X Cp X (delta T)

Regards,

Speco (
 
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