| 摘要 |
A fire tube boiler (1) employing hot water as heat medium and for gas firing is divided into two water chambers (2 and 3). The flue (4) is situated in the first water chamber (2), and the smoke tubes (5) are situated in the second water chamber (3). The water chambers (2 and 3) are interconnected by means of a connecting channel (7) provided with a temperature sensor (8). The temperature sensor controls a valve (10) situated in the connecting channel (7) or preferably on the return stub (9) of the boiler (1) in such a manner that the water leaving the connecting channel (7) in order to enter the second water chamber (3) is of a temperature higher than or equal to the dew point temperature of the smoke. In this manner the boiler can operate without the addition of supply water to the return water irrespective of the temperature of said return water, i.e. without a shunt circuit. Furthermore the correct heating surface temperatures are ensured solely by a control of the water flow through the boiler, and the boiler is automatically closed from the plant during idle periods. As a consequence thereof the burner of the boiler need not keep the boiler hot during the idle periods which provides a reduced consumption of fuel. |
