| 摘要 |
<p>The flue gas duct is intended for a water-heating boiler, and is in the form of a heat exchanger, with one or more flue ducts (18) and one or more water feed channels (20). The water feed channel can be divided into two sections with separate unions, one for heating and the other for service water. The duct can comprise two concentric tubes, the inner one for the flue gases, and the outer one for the water. The latter runs in a spiral round the inner one, or has guide baffles directing the water flow in a spiral pattern.</p> |
