Abstract: Interaction between two different species of particles in a fluid stream is promoted by generating turbulent eddies in the fluid stream. The turbulent eddies are designed to be of such size and/or intensity that the two species of particles are entrained into the eddies to significantly different extents. Consequently, the different species of particles follow different trajectories, and the likelihood of collisions or interactions between the particles is increased. Optimum collision rates will occur for a system which maintains a Stokes Number (St) much less than 1 for one species, and or order 1 or greater for the other species. The invention has particular application in air pollution control, by promoting agglomeration of fine pollutant particles in air streams into larger particles to thereby facilitate their subsequent removal from the air streams.

Abstract: A reactor cools humidifies gases produced by combustion or the like. The reactor has a chamber with an inlet at a lower end to receive a flow of gas, and an outlet at a upper end. The gas flows in a generally upward direction through the reactor. The horizontal cross-section of the chamber increases with height and the flow velocity of the gas decreases as it flows upwardly. The reactor includes at least one device for injecting water droplets into the upper region of the chamber, counter to the gas flow. As the water droplets fall, they gradually evaporate and lose mass and encounter a counterflow of increasingly higher velocity and temperature until the force of the upwardly flowing gas is sufficient to reverse their flow and carry them in an upward direction.

Abstract: A reactor cools humidifies gases produced by combustion or the like. The reactor has a chamber with an inlet at a lower end to receive a flow of gas, and an outlet at a upper end. The gas flows in a generally upward direction through the reactor. The horizontal cross-section of the chamber increases with height and the flow velocity of the gas decreases as it flows upwardly. The reactor includes at least one device for injecting water droplets into the upper region of the chamber, counter to the gas flow. As the water droplets fall, they gradually evaporate and lose mass and encounter a counterflow of increasingly higher velocity and temperature until the force of the upwardly flowing gas is sufficient to reverse their flow and carry them in an upward direction.

Abstract: Interaction between two different species of particles in a fluid stream is promoted by generating turbulent eddies in the fluid stream. The turbulent eddies are designed to be of such size and/or intensity that the two species of particles are entrained into the eddies to significantly different extents. Consequently, the different species of particles follow different trajectories, and the likelihood of collisions or interactions between the particles is increased. Optimum collision rates will occur for a system which maintains a Stokes Number (St) much less than 1 for one species, and or order 1 or greater for the other species. The invention has particular application in air pollution control, by promoting agglomeration of fine pollutant particles in air streams into larger particles to thereby facilitate their subsequent removal from the air streams.

Abstract: The energisation of an electrostatic precipitator is controlled in order to reduce arcing and/or back corona between the precipitator electrodes, using the precipitator current as a feedback parameter. A high speed switching device is used to control the energisation of the precipitator electrodes so that the precipitator current is regulated to a desired level with a response time that is significantly less than the arc generation time constant. The energisation is controlled so that the precipitator current is regulated to a predetermined value below the current level at which arcing occurs. The energisation response is proportional to the severity of the arcing, which can be based on the power and frequency of arcing. If back corona is detected, the energisation can also be controlled to reduce back corona.

Abstract: Interaction between two different species of particle(s) in a fluid stream is promoted by generating turbulent eddies in a fluid stream. The turbulent eddies are designed to be of such size and/or intensity that the different sized particle(s) are entrained into the eddies to significantly different extents and forced to follow different trajectories, increasing the likelihood of collisions and interactions. Optimum collision rates will occur for a system which maintains a Stokes Number much less than 1 for one sized particle, and or order 1 or greater for the other sized particle. The invention has particular application in air pollution control, whereby agglomeration of fine particles into larger particles is promoted, subsequent to their removal.

Abstract: An electrostatic filter (1) has a chamber (11) into which a gas stream is introduced. An ioniser (19) in the form of an electrode array (20) is located in the chamber (11) and creates an ionising zone through which the gas stream passes. A charged outlet (21) is located downstream from the ioniser (19). As the gas stream passes through the ionising zone, the unwanted particles therein are charged and urged away from the outlet (21) by the ioniser (19). Charged particles approaching the outlet (21) are also electrostatically repelled therefrom, permitting “clean” gas to be extracted through the outlet.

Abstract: Fine particles of dust and other pollutants in gas streams are agglomerated to form larger particles which are more easily filtered in downstream processing. In one embodiment, particles in successive portions of the gas stream are charged with opposite polarity, and the gas stream is introduced into an Evasé portion (12) to slow it down. Particles of different sizes have differential deceleration and therefore mix generally in the direction of flow, leading to agglomeration of oppositely-charged particles. In another embodiment, a gas stream is divided into substreams in respective parallel passages, and the particles in adjacent passages are charged to opposite polarity. Deflectors at the downstream end of the passages cause substreams of particles of opposite polarity to mix, with resultant agglomeration of oppositely charged particles.

Abstract: An electrostatic filter (1) has a chamber (11) into which a gas stream is introduced. An ioniser (19) in the form of an electrode array (20) is located in the chamber (11) and creates an ionising zone through which the gas stream passes. A charged outlet (21) is located downstream from the ioniser (19). As the gas stream passes through the ionising zone, the unwanted particles therein are charged and urged away from the outlet (21) by the ioniser (19). Charged particles approaching the outlet (21) are also electrostatically repelled therefrom, permitting “clean” gas to be extracted through the outlet.