Method for purification of waste gases
AssigneeA. Ahlstrom Corporation
InventorReijo J. Kuivalainen
Life of this patent
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Abstract
A method which provides purification of waste gases by adding particles of reagent and/or absorbent, which react with the pollutants in the waste gases, to the gases, and by introducing the gases into a wetting reactor for activating the reagent or absorbent contained in the gases. Gases are conveyed to at least two levels in the reactor through inlets so that a first portion of the gases is introduced into a wetting zone and a second portion of the gases below the wetting zone. A high density of particles is maintained in the wetting zone by recycling to the wetting zone particles separated from the gas above the wetting zone.
Claims19
A method of purifying of high temperature gases produced during chemical reactions, and containing pollutants therein, utilizing a wetting reactor having at least first and second different levels, and including a first, wetting, zone with spray nozzles at the first level, and a second zone below the first, wetting, zone at the second level, and a third zone above the first, wetting, zone, the third zone including a purified gas outlet;
- said method comprising the steps of:
- (a) outside the wetting reactor, adding to the gases containing pollutants, particles of reagent or absorbent or both, capable of reacting with the pollutants in the gases, to produce a suspension of gas and reagent or absorbent or both having a first particle concentration;
- (b) activating the reagent or absorbent or both by introducing a first portion of the suspension from step (a) into the first level of the wetting reactor, and introducing a second portion of the suspension from step (a) into the second level of the wetting reactor, and with the nozzles spraying water or steam or both into the wetting reactor to wet particles in the suspension in the first, wetting, zone;
- (c) causing the gases of the suspension portions introduced at the first and second levels to flow upwardly into the third zone, while causing wetted particles of the suspension to flow downwardly through the first, wetting, zone countercurrent to the gases;
- (d) separating particles in the gases from the gases in the third zone;
- (e) effecting an internal recirculation of particles separated in the third zone to at least the first, wetting, zone, so that the particle concentration within the wetting reactor below the third zone is higher than the first particle concentration;
- and
- (f) discharging purified gases from the purified gas outlet.
A method of purifying gases produced during chemical reactions, and containing pollutants therein, utilizing a wetting reactor having at least first and second different levels, and including a first, wetting, zone with spray nozzles at the first level, a second zone below the first, wetting zone at a second level, and a third zone above the first, wetting zone, the third zone including a purified gas outlet;
- said method comprising the steps of:
- (a) outside the wetting reactor, adding to the gases containing pollutants, particles capable of reacting with the pollutants and the gases, to produce a suspension of gas and particles having a first particle concentration;
- (b) introducing a first portion of the suspension from step (a) into the first level of the wetting reactor;
- (c) introducing a second portion of the suspension from step (a) into the second level of the wetting reactor;
- (d) with the spray nozzles, spraying water or steam or both into the wetting reactor to wet particles in the suspension in the first, wetting, zone;
- (e) separating particles in the gases from gases in the third zone;
- (f) effecting an internal recirculation of particles separated in the third zone to at least the first, wetting, zone, so that the particle concentration within the wetting reactor below the third zone is higher than the first particle concentration;
- and
- (g) discharging purified gases from the purified gas outlet.
Dependencies are inferred from the claim text.