| 摘要 |
Corrosion-resistant air heater using combustion products coming from thermal equipment and containing polluting and corrosive agents, such as particularly oxidised compounds of sulphur and sodium and vanadium salts, which comprises at least one bundle of tubes, through which the air to be heated passes and which are placed in the path of the corrosive fumes before they pass into the atmosphere, said corrosive fumes circulating in counterflow with the air to be heated which passes through the tubes. This heater is characterised in that it comprises a protective tube bundle (24, 24') located upstream of said bundle of tubes (18, 16), this protective bundle being supplied with a constant stream of cold air circulating in the same direction as the fumes, this flow of cold air and the exchange surface of said protective bundle being selected in such a way that the temperature of the first tubes (18) of the tube bundle of the heater (10) is always below the critical temperature of corrosion by sodium and vanadium, and in that the constant air flow leaving said protective bundle is subsequently redistributed at the entrance or exit of the tube bundle of the heater (10), depending on the particular operating conditions, in such a way that the skin temperature of the tubes of this tube bundle is always slightly higher than the temperature of the acid dew point of the fumes. …<IMAGE>… |
