Exercise-3 

A furnace is to be designed to carry out an exothermic gas solid reaction on a continuous basis. Both gaseous and solid reactants are to be fed continuously at a uniform total rate of  and at . The reaction products are to be discharged continuously at . The heat of reaction of total reactants is . The average specific heat of the reaction products is .

The reaction chamber is a vertical Inconel cylinder,  in diameter and 3ft high, with suitable auxiliary facilities for continuous feed and discharge. Assume that the whole lnconel cylinder is maintained at .

The Inconel cylinder will be insulated on the outside with a refractory material for which  and . Will a  layer of insulation (making total furnace diameter   allow to operate furnace autogenously?  Make other reasonable assumption if necessary.



Use 

Solution:

 

 

 

This heat must be dissipated in order to maintain  furnace temperature.
Heat balance is

 

.
Solution gives

Heat loss would be  which is lower than.
Hence  feet layer is not sufficient.