Mercury absorption system for industrial kiln applications
AssigneeFLSmidth A/S
InventorPeter T. Paone, III
Life of this patent
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Abstract
Disclosed is a method for the reduction of mercury emissions from an industrial plant utilizing a cement or minerals kiln that has a high level of mercury. The invention allows for the repeated treatment of a gas stream to reduce the level of mercury and other pollutants through reduction steps, allowing targeted treatment of specific compounds. The invention utilizes multiple sorbent injections for the step-wise reduction in pollutants. Utilizing the multiple stages of reaction, very high levels of mercury emissions may be controlled to greater reduction percentages than existing methods.
Claims21
A method for the reduction of contaminant emissions including mercury present in vaporized form from the process gases of an industrial plant utilizing a kiln to heat treat a raw material, said method comprising
- (i) directing plant process gases from the plant to a first air pollution control device having a process gas inlet and exit to dedust the process gases;
- (ii) directing the dedusted process gases from the first air pollution control device to a cooling means having a process gas inlet and outlet wherein the dedusted gases are cooled to near the condensation temperature of the contaminants;
- (iii) absorbing such contaminants on a first amount of sorbent that is entrained in the dedusted process gases;
- (iv) directing the process gases in which the first amount of sorbent with absorbed contaminants is entrained from the cooling means to a separation device wherein said sorbent with absorbed mercury is separated from the process gases;
- (v) contacting the process gases from which the sorbent with absorbed mercury was separated with a second amount of sorbent that entrains in the process gases and absorbs contaminants in the process gases;
- and
- (vi) directing the process gases in which the second amount of sorbent with absorbed contaminants is entrained to a second air pollution control device having a process gas inlet and exit wherein said sorbent is separated from the off gases.
A system for reducing contaminants in the process gases of an industrial plant, said contaminants being condensable and including mercury, comprising,
- a kiln for heat treating comminuted raw material;
- a preheater located, in the direction of material flow, upstream from the kiln for preheating the comminuted raw material with off gases from the kiln;
- a first air pollution control device for dedusting process gases;
- means to direct off gases from one or both of the kiln or preheater to the first air pollution device for dedusting;
- a cooling device for cooling dedusted process gases to a temperature near the condensation temperature of mercury;
- means to direct the dedusted gases from the first air pollution control device to the cooling device;
- means to direct a first sorbent for absorbing the mercury into the cooling device for entrainment in the dedusted gases;
- a separation device located downstream from the cooling device for separating entrained sorbent containing absorbed contaminants from the cooled process gases and means to directing at least a portion of the separated sorbent back to the cooling device.
Dependencies are inferred from the claim text.