| 摘要 |
A recirculating air heater for an oven is fired by a burner and connected with the oven by a return air duct and an outlet duct. The return air duct has two sets of louvers for admitting controlled amounts of return air to a combustion chamber and a burner bypass chamber in the oven. The combustion gases and return air in the combustion chamber are mixed and directed through a catalytic converter before being mixed with the return air in the burner bypass chamber and directed back into the oven. A portion of the gases directed through the catalytic converter are discharged to atmosphere and an equal amount of preheated fresh air is admitted to the heater. The inlet and exhaust ducts are provided with blowers and dampers so that the mass flow rates of fresh air and exhaust air are substantially equal. During oven preheating some of the combustion gases and heated return air are caused to bypass the catalytic converter and flow directly back into the oven. |
