Patent GB-719725-A (GB)
Title: Improvements in plant for the removal of ash and dust
Inventor: PROLE JOHN HAROLD ARNOLD
IPC: F23J3/06
Filed: 1952-03-24
Abstract: 719,725. Ash removal from furnaces. BABCOCK & WILCOX, Ltd. March 23, 1953, [March 24, 1952.] No. 7535/52. Class 78 (1). In plant for the removal of ash and dust arising from the combustion of pulverized fuel in the furnace of a steam boiler, ashes from a collecting chamber 5 disposed below the ash outlet 4 of the furnace and fine dust particles from a gas pass 20 are discharged by water at relatively high pressure issuing from nozzles 12, 21, respectively, on to an inclined sluiceway 16 down which they are washed by water at relatively low pressure supplied by a nozzle 36 to ash pits 43a, 43b. Each. pit holds the daily output of ash and they are used alternatively by diverting the discharge from the sluiceway 16 to a branch 16a or 16b by moving the valve 41. The pits are divided by a central wall 44, Fig. 3, of less height than their sides and are closed at the end remote from the sluiceway by a water-permeable wall 45 composed of pre-formed concrete elements 48, Fig. 6. This wall separates the ash pits from a drain pit 60, the bottom 61 of which is below the level of the bottoms of the pits 43a, 43b and slopes downwardly towards a suction pit 62 in which are the inlets 68 of a pair of low pressure rotary pumps 65, only one of which is in use at a time. The pumps are in a pit 64 which is separated from the pit 62 by a water-impervious wall 63. The outlet of the pumps is connected to the pipe 37 supplying the nozzle 36 and also to a pipe 72 delivering to a shallow trough 73 extending along the side of a reservoir 74. The lip 77 of this trough consists of a number of relatively short lengths of metal plate which are adjustable vertically. The bottom 78 of the reservoir 74 slopes downwards to a trough 79 in which are the inlet ends of pipes 80, 83. The pipe 80, which has stop valves 81, 82 actuated manually and automatically, respectively, opens into the pit 60. The pipe 83 has similar valves 84, 85 and an overflow pipe 86 which terminates at 87 above the normal level of the water in the reservoir 74. The pipe 83 opens into a trough 88 at one end of a long settling tank 90 which is arranged below the level of the reservoir 74 with its bottom higher than the bottoms of the pits 43a, 43b. The inlets 96 to two high-pressure pumps 93 and a low-pressure pump 97 are at the other end of the tank go and are shielded by a wire mesh screen 91 placed across the tank. Only one of the pumps 93 is in use at any time. The pumps 93 deliver to the pipe 22 which supplies the nozzles 12, 21 and the pump 97 discharges to waste. The valve 82 is controlled in accordance with the water level in the pit 62 by means which include pendant electrodes 120a, 120b, 120c, Figs. 2, 6, with their lower ends at different levels and an electromagneticallyoperated relay provided with a hold-on winding of the kind described in. Specification 449,453, [Group XXXV]. These means control a circuit which when energized causes the valve 82 to open when the water level falls to a ... a, Fig. 6, and when de-energized causes the valve to close when the water level rises to b ... b. An excessive rise in the water level is prevented by electrodes 121a, 121b, 121c which control the energization of the motors 69 driving the pumps 65 in accordance with the level of the water. A manually operated switch is provided by which the motors may be energized regardless of the water level. Similar means are provided in the end portion goa of the tank go for maintaining a minimum predetermined water level and preventing an excessive rise. A transporter 110 runs on rails extending along the plant and carries a grab 111 which transfers the ash from the pits 43a, 43b, the reservoir 74 and the settling tank go to a barge 117 or to a concrete platform 114 on which it may be left .to drain.