Removal of mercury from a combustion gas stream and apparatus
AssigneeBrooks Rand Inc
InventorRichard J. Brooks
Life of this patent
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Abstract
in a hot combustion gas stream are removed therefrom by oxidizing the elemental mercury, to form a mercury compound, and adsorbing the mercury compounds on adsorbent particles such as activated alumina. Oxidation is catalytically promoted. After adsorbing a substantial quantity of mercury compounds, the spent adsorbent particles can be regenerated and re-used by heating the particles to decompose and drive off the mercury compounds. In another embodiment, oxidation of the elemental mercury is catalytically promoted at a catalyzing station, and the mercury compounds are removed from the gas stream by scrubbing.
Claims64
A method for removing, from a stream of combustion gas flowing into the stack of a combustion system, elemental mercury and mercury compounds contained in said gas, said method comprising the steps of:
- flowing a stream of combustion gas containing elemental mercury and mercury compounds downstream toward a combustion system stack;
- oxidizing the elemental mercury contained in said combustion gas, upstream of said stack, either with or without supplemental oxidizing, to produce therefrom at least one compound of mercury;
- providing a mass of adsorbent particles each having a surface substantially the totality of which is relatively adsorbent to said previously-recited mercury compounds and relatively non-adsorbent to said elemental mercury;
- directing said stream into said mass;
- adsorbing, on said surfaces of said mass of adsorbent particles, said previously-recited mercury compounds;
- and then releasing the combustion gas stream into the atmosphere outside said combustion system, after the performance of said adsorbing step;
- said adsorbent particles (i) having a catalytic activity for the oxidation of mercury, at least substantially comparable to that of activated alumina particles and (ii) being sufficiently heat-resistant to accommodate a regeneration process for removing the adsorbed mercury compounds therefrom by heating above the decomposition temperature of said mercury compounds and above the vaporization temperature of mercury to drive off the mercury-containing materials adsorbed on said mass of adsorbent particles.
An apparatus for removing, from a stream of combustion gas flowing into the stack of a combustion system, elemental mercury and mercury compounds contained in said stream, said apparatus comprising:
- means for enabling the oxidation, upstream of said stack, of elemental mercury contained in said stream, to produce a mercury compound;
- a bed located upstream of said stack, said bed comprising a mass of adsorbent particles each having a surface substantially the totality of which is relatively adsorbent to said previously-recited mercury compounds and relatively non-adsorbent to said elemental mercury;
- means for directing said stream through said bed;
- said mass of adsorbent particles comprising means for adsorbing on said surfaces said previously-recited mercury compounds;
- and means for releasing said stream into the atmosphere outside said combustion system, after said stream has passed through said bed;
- said adsorbent particles (i) having a catalytic activity for the oxidation of mercury, at least substantially comparable to that of activated alumina particles and (ii) being sufficiently heat-resistant to accommodate a regeneration process for removing the adsorbed mercury compounds therefrom by heating above the decomposition temperature of said mercury compounds and above the vaporization temperature of mercury to drive off the mercury-containing materials adsorbed on said mass of adsorbent particles.
A method for removing, from a stream of combustion gas flowing into the exhaust stack of a combustion system, elemental mercury and mercury compounds contained in said gas, said method comprising the steps of:
- flowing a stream of combustion gas containing elemental mercury and mercury compounds downstream toward a combustion system stack;
- flowing said gas stream through a catalyzing station located upstream of said stack;
- catalytically promoting the oxidation of at least a major portion of said elemental mercury entering said catalyzing station, in response to the flowing of said gas stream through said catalyzing station, to produce, from said elemental mercury, at least one compound of mercury;
- flowing said gas stream through a mercury compound removal station located downstream of said catalyzing station;
- removing at least a major part of said previously recited mercury compounds from said gas stream in response to the flowing of said gas stream through said removal station;
- and then releasing the combustion gas stream into the atmosphere outside said combustion system, through said stack, after said removing step.
In a combustion system having an exhaust stack, an apparatus for removing, from a stream of combustion gas flowing into said stack, elemental mercury and mercury compounds contained in said gas, said apparatus comprising:
- a catalyzing station located upstream of said stack;
- means for flowing said gas stream through said catalyzing station;
- said catalyzing station comprising means for catalytically promoting the oxidation of at least a major portion of said elemental mercury entering said catalyzing station, in response to the flowing of said gas stream through said catalyzing station, to produce, from said elemental mercury, at least one compound of mercury;
- a mercury compound removal station located downstream of said catalyzing station;
- means for flowing said gas stream through said removal station;
- said removal station comprising means for removing at least a major part of said previously recited mercury compounds from said gas stream in response to the flowing of said gas stream through said removal station;
- and means for releasing the combustion gas stream into the atmosphere outside said combustion system, through said stack, after said removing step.
Dependencies are inferred from the claim text.