GB331583A - Air heating installations for furnaces - Google Patents

Abstract

331,583. Howden & Co., Ltd., J., and Hume, J. H. April 6, 1929. Regenerators.-An air heating installation for boiler furnaces of the kind comprising nests of tubes or corrugated plates comprises a casing divided by partitions into sections having baffles whereby one supply of air passes through at least one air pass of a section and is delivered to the furnace as heated forced draught secondary air and another supply of air passes through at least two passes of a heater section and is delivered as heated primary air. Fig. 1 shows a tubular air heater for a pulverized-fuel furnace divided by partitions 6 into wing sections 7 for secondary air and a central section 8 for primary air. Air is supplied by a fan to the inlets 10 of the wing sections and is caused to take a tortuous path by baffles 9 over the waste gas tubes 3 and is finally delivered as secondary air to the furnace through the legs 12. Air enters the primary air heater from the atmosphere through the inlet 16 and is caused by a baffle 14 to pass back and forth over the tubes 3 before leaving by the outlet 17 connected to the pulverized fuel fan. The inlet 16 may be supplied by the fan connected to the air inlets 10. When primary air is required at a higher temperature than the secondary air the primary air heater 8 is divided by baffles into four passes and receives air from the atmosphere or from one of the passes of the secondary air heaters 7. Fig. 6 shows an air heater for furnaces having grates adapted to supply air at a higher temperature above the grate than below. The heater is of the corrugated plate type and comprises two sections A. Air is supplied to a chamber 26 of each section and is divided into two independent streams. One stream for delivery below the firebars passes as shown by arrows through the passages 35 - - 38 and 24 and the other stream for delivery above the firebars through passages 27 - - 34 and 23. A slightly modified arrangement is employed for boiler furnaces employing pulverized fuel in which the primary air for the pulverizer is required at the highest possible temperature. The secondary air makes four passes of the corrugated plate heater and then divides into two parts, one part passes direct to the furnace and the 'remainder passes through two subsidiary passes and is further heated for use as primary air. Where space is limited, one pass only of each heater section is used for secondary air, while four subsidiary passes at the bottom of each section are employed for the primary air supplied to the pulverizer. Various other arrangements of primary and secondary air passages in the heater sections are also described and illustrated.