摘要:
In the pipestill heater (10), the combustion devices (30) are each provided with an air permeable heat accumulator (32) made of a refractory material, a duct part (33) having an oxidizing agent supply path (36) and an exhaust gas discharge path (37), whereby the oxidizing agent for combustion is heated by the exhaust gas through the heat accumulator. The duct part is provided with rotating means (45) to change the area of the heat accumulator for passing the oxidizing agent.