Method and system for controlling mercury emissions from coal-fired thermal processes
First Claim
Patent Images
1. A method, comprising:
- providing a mercury-containing gas stream comprising vapor-phase mercury, a vapor-phase iodine, and ash particulates;
introducing a reactive surface agent into the mercury-containing gas stream to form particulates comprising at least part of the vapor-phase mercury and the reactive surface agent; and
thereafter removing particulates from the mercury-containing gas stream to form a treated stream, at least a portion of the vapor-phase mercury being removed from the mercury-containing gas stream with removal of the particulates, wherein at least one of the following is true;
(i) the mercury-containing gas stream comprises about 3.5 ppmw or less vapor-phase iodine;
(ii) in the mercury-containing gas stream, a molar ratio of vapor-phase iodine to vapor-phase mercury is no more than about 600;
(iii) at an air preheater outlet, a concentration of vapor-phase iodine ranges from about 0.1 to about 10 ppmw; and
(iv) a concentration of the iodine is about 30 ppmw or less relative to a weight of a mercury-containing feed material producing the vapor-phase mercury.
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Abstract
The present disclosure is directed to the use of elemental or speciated iodine and bromine to control total mercury emissions.
304 Citations
35 Claims
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1. A method, comprising:
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providing a mercury-containing gas stream comprising vapor-phase mercury, a vapor-phase iodine, and ash particulates; introducing a reactive surface agent into the mercury-containing gas stream to form particulates comprising at least part of the vapor-phase mercury and the reactive surface agent; and thereafter removing particulates from the mercury-containing gas stream to form a treated stream, at least a portion of the vapor-phase mercury being removed from the mercury-containing gas stream with removal of the particulates, wherein at least one of the following is true; (i) the mercury-containing gas stream comprises about 3.5 ppmw or less vapor-phase iodine; (ii) in the mercury-containing gas stream, a molar ratio of vapor-phase iodine to vapor-phase mercury is no more than about 600; (iii) at an air preheater outlet, a concentration of vapor-phase iodine ranges from about 0.1 to about 10 ppmw; and (iv) a concentration of the iodine is about 30 ppmw or less relative to a weight of a mercury-containing feed material producing the vapor-phase mercury. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method, comprising:
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providing a mercury-containing gas stream comprising vapor-phase mercury and a vapor-phase halogen; contacting the mercury-containing gas stream with a reactive surface agent upstream of an air preheater to form particulates comprising at least part of the vapor-phase mercury; and removing the particulates from the mercury-containing gas stream. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification