GB340780A - Improvements in furnaces - Google Patents

Abstract

340,780. Returning combustion products to furnaces. BABCOCK & WILCOX, Ltd., Babcock House, Farringdon Street, London.-(Babcock & Wilcox Co. ; 85, Liberty Street, New York, U.S.A.) Jan. 2, 1930, No. 109. [Class 51 (i).] A furnace for heating fluids such as oil, mercury &c. where it is undesirable to subject the heating surfaces to very high temperatures comprises a flue 13 leading upwardly from a combustion chamber 10 and containing a heat transfer device 22, and a downwardly-extending flue 16 for returning part of the gases to the combustion chamber, separated from the flue 13 by a partition wall 14 and connected with a horizontal flue overlying the combustion chamber and communicating therewith by an opening 19 above a combustion arch 12 over the burner 11. The gases pass upwardly through the flue 15, over the fluid heater 22, through a flue 25 to an air preheater 26 and through an induced draught fan 29 to the gas outlet 30. A curved gas-deflecting plate 24 located in the flue 25 diverts some of the cooled waste gases into the flue 16 in which they flow downwardly, owing to the difference in density between these gases and the hot gases in the flue 15, and enter the combustion chamber through openings 18, 19 in the roof 17 controlled by dampers 20, 21. The amount of waste gases returned to the furnace may be regulated by a damper 22<1> and air may be mixed with the waste gases, entering through openings 23. The combustion arch 12 provided above the burner 11 is kept cool by the waste gases entering through the opening 19. The fluid heater 22 may be partly in each flue 15, 16. In starting up the furnace the dampers 20, 21 are closed. Air is drawn through the preheater 26 by a fan and supplied to the burner 11 through conduits 32. The furnace may be of the chain grate or stoker fired type.