GB1248912A - Improvements in or relating to self-recuperative burners for furnaces - Google Patents

Abstract

1,248,912. Burners; concentric-tube heat exchangers. GAS COUNCIL. 12 May, 1969 [14 Feb., 1968], No. 7196/68. Headings F4S and F4T. A self recuperative furnace burner in which fuel and combustion air are delivered separately by way of coaxial passages 10 and 42 respectively to a nozzle 14 or respective nozzles directed into a combustion chamber 33, where the fuel and air are ignited, includes a heat exchanger through which the products of combustion pass in counterflow to the combustion air to preheat the combustion air and which comprises a products passage 40 coaxial with and in heat exchange relationship with the air passage 42 which products passage 40 extends from the combustion chamber 33 and is then doubled back upon itself at the end of the heat exchanger remote from the nozzle 14 to form a double-back part so that products of combustion are caused to flow back towards the nozzle 14 before they leave the heat exchanger, an outer air passage 45 being provided which leads to the air passage 42 and surrounds the doubled-back part of the products passage 40 and through which air passes in counterflow to the products of combustion in the doubled-back part of the products passage 40. The fuel passage comprises a pipe 10 surrounded by a coaxial cylindrical casing 23 and in the annular space between the pipe 10 and the casing 23 is defined the passages of the heat exchanger by means of coaxial tubes 25, 26, 27, 28. The two parts of the products passage 40 are defined respectively between the tube 25 and the tube 26, and between the tube 27 and the tube 28, the space between the tube 26 and the tube 27 being dead space, and the outer air passage 45 is defined between the tube 28 and the casing 23. Annular end pieces 37, 38 respectively interconnect the tubes 26 and 27, and the tubes 25 and 28 at their ends remote from the nozzle 14, and the heat exchanger is surrounded by insulating jackets 35 and 36. The outer air passage 45 is supplied by an inlet 46 which opens either tangentially, Fig. 3 (not shown) or volutely, Fig. 4 (not shown) into the casing 23 and the air passage 42 leading to the nozzle 14 is formed between the fuel pipe 10 and the tube 25 which are interconnected remote from the nozzle 14 by an end wall 23<SP>1</SP>. The mixture in the chamber 33 is ignited by an ignition electrode 20 and either a flame detector electrode (22), Fig. 5, (not shown) is included, or an inspection window is provided in a plate 11 at the rear of the fuel pipe 10 and one or more holes in the nozzle 14 through which the combustion chamber may be viewed. The products passage 40 may be provided with flow guides in the form of angularly spaced fins.