Abstract: Reduction of nitrogen oxides emissions from large scale combustors, such as coal-fired boilers and incinerators which produce effluents with high solids concentrations, is improved. High solids loading and other operational factors can cause such large temperature gradients transverse to the direction of effluent flow that SNCR cannot be practiced in conventional fashion. The process entails defining a near-wall zone having a temperature effective for SNCR and a central zone where the temperature is too high. NOx-reducing composition is introduced into the effluent within the near-wall zone in fine droplets, and can be introduced into the central zone after the gases have cooled or as large droplets effective to survive the high temperatures.

Abstract: The removal of SO.sub.x and particulates, and preferably also NO.sub.x, from the combustion gases of a large boiler, is simplified while efficiency is improved. In a primary treatment zone, a slurry comprising an alkaline SO.sub.x -reducing composition and preferably a nitrogen-containing composition effective to reduce NO.sub.x, is introduced into combustion gases at a temperature of from about 900.degree. to about 1300.degree. C. The gases are cooled by initial contact with steam-generating means, and then by contact with an gas-to-gas heat exchanger. Cooled gases are then subjected to a secondary treatment in which they are first humidified and further cooled by introduction of a water spray or aerosol to reduce the temperature to 100.degree. C. or below. Contact between the SO.sub.x -reducing composition and the humidified gases is maintained for a reaction period of at least 2 seconds. Particulate solids are then separated from the gases with a fabric filter.

Abstract: A fluidizing feed apparatus (20) for supplying particulate material to a fluidized bed furnace (12) having a housing (22) which defines a chamber which is divided by a multi-tiered perforated distribution plate (24) into a plurality of independent gas plenums (26, 36, 52) beneath the respective tiers (23, 25, 27) of the distribution plate, a particulate fluidizing plenum (28) above the upper outer position (25) of the distribution plate (24) and a particulate feed plenum (30) superadjacent the lower central portion (25) of the distribution plate (24). Conveying gas is independently fed under pressure to each of the gas plenums to pass upwardly through the respective tiers of the perforated distribution plate.

Abstract: A fluidizing feed apparatus (20) for supplying particulate material to a fluidized bed furnace (12). A housing (22) defines a chamber which is divided by a perforated distribution plate (24) into a gas plenum (26) beneath the plate and a particulate fluidizing plenum (28) above the plate. Conveying gas is fed under pressure to the gas plenum to pass upwardly therefrom through the perforated distribution plate. The upwardly directed conveying gas fluidizes the particulate material so as to establish a discrete bed (60) of fluidized particulate material superadjacent the distribution plate (24) and a splash zone (70) thereabove. Transport conduits (14) open into the splash zone (70) at a selected distance above the surface (65) of the discrete bed (60) to receive particulate material and conveying gas therefrom for transport to the fluidized bed (16) of the furnace (12).

Abstract: A loose fitting movable cover plate (36), suitable for the severe service encountered in a fluidized bed combustor (10), restricts the flow of solids into the combustor drain lines (30) during shutdown of the bed. This cover makes it possible to empty spent solids from the bed drain lines which would otherwise plug the piping between the drain and the downstream metering device. This enables use of multiple drain lines each with a separate metering device for the control of solids flow rate.

Abstract: Apparatus for supporting a perforated plate (24) air distributor for a fluidized bed combustion boiler. The plate (24) is supported (26) around its entire periphery, and at given points (42) within its periphery, in such a manner that it is free to expand due to thermal growth in a horizontal direction, while still being capable of supporting a vertical load (12) without sagging, buckling, or being subject to failure.

Abstract: The air-supply system for a fluidized-bed furnace includes two air conduits for the same combustion zone. The conduits feed separate sets of holes in a distributor plate through which fluidizing air flows to reach the bed. During normal operation, only one conduit and set of holes is used, but the second conduit and set of holes is employed during start-up.