| 摘要 |
PROBLEM TO BE SOLVED: To lower the heat loss, lower the heating load at the start-up time, and miniaturize and simplify an apparatus by preventing a circulating gas in a circulating gas route for a furnace containing a solvent vapor for a coating material from passing a directly heating-type combustion heating apparatus. SOLUTION: Directly heating type combustion heating apparatuses 19b, 19c for a furnace are respectively installed in a first and a second heat keeping zones 1b, 1c. Fresh air OA not yet containing a solvent vapor for a coating material is heated and mixed with a circulating gas RA in the circulating gas route 9b, 9c for the furnace to heat the insides of the zones 19b, 19c. Moreover, a part of a high temperature clean gas PA in a circulating gas route 20 for heat radiation which does not contain the solvent vapor for the coating material is separated as a high temperature clean gas PA" and mixed with the circulated gas RA in a circulating gas route 9a for the furnace. With this structure, the solvent vapor for the coating material in the circulating gas RA in the circulating gas routes 19a-19c for the furnace is prevented from being exposed to and reacted with burning flame and thus reaction product formation can be prevented. |
