| 摘要 |
<p>A natural draft, catalytic heater (10) comprises a tubular body (16) which defines an elongated fluid flow passage (24) having an air/fuel mixture inlet (26) at one end and a combustion product outlet (34) at the other end thereof. A secondary catalytic burner (52) is disposed within the passage (32) downstream of the primary catalytic burner (50) for completing combustion of any un-oxidised fuel in the exhaust from the primary catalytic burner (50). Low pressure drop through the primary burner (50) is achieved by a tubular burner construction held against the passage wall and combustion of most of the reactants is achieved by providing an appropriate catalyst surface area. A stirring element (76) may be placed within the burner (50) for gently urging reactants outwardly towards the catalyst. A low pressure drop through the secondary burner (52) is achieved by providing a plurality of axial passages which present relatively little resistance to gas flow. The surfaces of the passages are coated with a catalyst material to ensure that any un-oxidized reactants are oxidised. <IMAGE></p> |
