Power plants – Combustion products used as motive fluid – With closed pocket turbine
Patent
1982-03-24
1984-09-11
Casaregola, Louis J.
Power plants
Combustion products used as motive fluid
With closed pocket turbine
60 39182, F02C 328
Patent
active
044702558
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to fluidised bed furnaces and to a power generating plant including a fluidised bed furnace.
According to one aspect of the invention there is provided a fluidised bed furnace including, connected in a circulatory arrangement, a combustion chamber section, a separating section and a heat transfer bed space section, the combustion chamber section being arranged to be supplied with fuel particles and fluidising gases at a relatively high velocity and discharge combustion products to the separating section, the separating section being arranged to effect separation of solids particles from combustion gases in the combustion products and discharge the solids particles to the heat transfer bed space section and the combustion gases from the furnace and the heat transfer bed space section being arranged to be supplied with fluidising gases at a relatively low velocity to effect flow of the solids particles around heat transfer surfaces and discharge to the combustion chamber section.
According to another aspect of the invention there is provided power generation plant including the fluidised bed furnace and a coal devolatilisation unit, the coal devolatilisation unit being connected to receive air from an air heater arranged to derive heat from the fluidised bed furnace and to discharge combustible gases to burner means connected to a gas turbine and the fluidised bed furnace being connected to receive char from the coal devolatilisation unit and exhaust gas from the gas turbine, and being provided with vapour generating and vapour heating surfaces in a heat transfer bed space of the fluidised bed furnace and in a combustion gas pass connected to discharge vapour to a vapour turbine.
The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:
FIG. 1 is a representation of a fluidised bed combustor together with a steam generating and heating unit;
FIG. 2 is an isometric representation of a form of fluidised bed combustor; and
FIG. 3 is a representation of the combustor in conjunction with gas turbine and coal devolatilisation plants.
As shown in FIG. 1, the fluidised bed combustor 2 includes an upright, refractory lined, combustion chamber 4 discharging through a lateral duct 6 from an upper region 8 to a separation region 10. A particulate solids return duct 12 extends downwardly from the separation region 10 to a weir chamber 14 having a weir plate 16 and, adjacent the weir plate, spaced fluidising air nozzles 18. The weir chamber 14 discharges, over the weir plate 16, to a heat transfer bed space 20 formed as parallel extending compartments by vertical partitions each provided with spaced fluidising air nozzles 22 and heat exchange tube banks 24. Particle recirculation ducts 26 lead from the bed space 20 to the combustion chamber 4.
The heat exchange tube banks 24 in the bed space 20 form a part of the flow circuit of a forced flow steam generating and superheating unit, the remaining tube banks 30, 32, 34 and 36 of which are positioned in a combustion gas pass 38 leading from the separation region 10. The flow circuit of the unit also includes tube lengths (not shown) lining the walls of the bed space 20 and the combustion gas pass 38. An airheater 40 is positioned in the combustion gas pass 38 downstream, in the gas flow path, of the tube bank 30 and the pass is connected to discharge, through a bag filter and induced draught fan, to a stack (all not shown).
The combustion chamber 4 is formed with a convergent base 42 provided with primary fluidising air nozzles 44, an inlet 46 for dust particles collected from the combustion gas pass 38 and the bag filter and an outlet 48 for ash particles. A screw feeder 50 for coal particles is positioned adjacent the level of the particle recirculation ducts 26 whilst secondary fluidising air nozzles 52 extend through the convergent base wall from a windbox 54 superjacent the screw feeder 50.
In operation, combustion is initiated in the combustion chamber 4 by utilising a
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patent: 3978657 (1976-09-01), Fulton et al.
patent: 3986348 (1976-10-01), Switzer
patent: 4103646 (1978-08-01), Yerushalmi et al.
patent: 4160009 (1979-07-01), Hamabe
Hilliard Peter T.
Pattle Derek G.
Rowlands William B. M.
Casaregola Louis J.
Fluidised Combustion Contractors Limited
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