Abstract: The invention provides methods and apparatuses for removing aerosols and, in some cases, vapor phase contaminants, such as mercury, from a gas stream. One method is directed to the removal of additional aerosols from a gas stream from which aerosols have previously been removed by using a screen in combination with a primary aerosol collection device. Another method is directed to the removal of both aerosols and vapor phase contaminants by using a sorbent in combination with a screen. Another method is directed to the removal of vapor phase contaminants by using a catalyst to convert the contaminant to a form that is more easily removed from the gas stream and optionally injecting a chemical to increase the rate of conversion. The invention also provides various apparatuses for use in performing the various methods of the invention.

Abstract: Methods and apparatuses are described for removing a contaminant, such as a vaporous trace metal contaminant like mercury, from a gas stream. In one embodiment, a primary particulate collection device that removes particulate matter is used. In this embodiment, a sorbent filter is placed within the housing of the primary particulate collection device, such as an electrostatic precipitator or a baghouse, to adsorb the contaminant of interest. In another embodiment, a sorbent filter is placed within a scrubber, such as a wet scrubber, to adsorb the contaminant of interest. In some embodiments, the invention provides methods and apparatuses that can advantageously be retrofit into existing particulate collection equipment. In some embodiments, the invention provides methods and apparatuses that in addition to removal of a contaminant additionally remove particulate matter from a gas stream.

Abstract: A staged-coal injection procedure for coal-fired boilers used in power generation. The procedure includes the steps of combusting a first type of coal in a first zone of a furnace; and combusting a second type of coal in a second zone of the furnace. The second zone is at a position separate from the first zone.

Abstract: The invention provides methods and apparatuses for removing additional aerosols and in some cases additional particulate matter from a gas stream, wherein a certain portion of such aerosols and particulate matter has already been removed using a primary aerosol and particulate collection device. In some embodiments, the invention comprises a method for removing additional aerosols from a gas stream that has aerosols previously removed by a primary aerosol collector, comprising passing a gas stream comprising a plurality of aerosols through a gas duct; removing a first portion of the plurality of said aerosols using a primary aerosol collector; passing the gas stream through a screen; and collecting at least a second portion of the plurality of aerosols on the screen. The invention also provides various apparatuses for use in performing the method of the invention.

Abstract: The present invention provides methods for removing particulate and a vapor phase contaminant from a gas stream including, in one embodiment, directing a gas stream comprising fly ash and a vapor phase contaminant into a particulate collection device, wherein the particulate collection device includes an upstream collection section and a downstream collection section; removing at least a portion of the fly ash from the gas stream in the upstream collection section; injecting a sorbent into the particulate control device between the upstream collection section and the downstream collection section; adsorbing the vapor phase contaminant onto the sorbent to produce spent sorbent; and removing the spent sorbent from the gas stream in the upstream collection section. An apparatus is also provided for performing the methods.

Abstract: The present invention provides a method and apparatus for reducing the concentration of NOx in a gas stream. In one embodiment, the method comprises injecting a reducing agent to a gas stream comprising NOx; injecting a NOx-reducing catalyst into the gas stream; chemically reducing at least a portion of the NOx using said reducing agent and the NOx-reducing catalyst, thereby producing nitrogen and spent NOx-reducing catalyst; and removing the spent NOx-reducing catalyst from the gas stream. The present invention also provides a method and apparatus for reducing the concentration of NOx and another vapor phase contaminant in a gas stream, wherein this additional contaminant is adsorbed by the NOx-reducing catalyst.

Abstract: The present invention provides methods for removing particulate and a vapor phase contaminant from a gas stream comprising, in one embodiment, directing a gas stream comprising fly ash and a vapor phase contaminant into a particulate collection device, wherein the particulate collection device comprises an upstream collection section and a downstream collection section; removing at least a portion of the fly ash from the gas stream in the upstream collection section; injecting a sorbent into the particulate control device between the upstream collection section and the downstream collection section; adsorbing the vapor phase contaminant onto the sorbent to produce spent sorbent; and removing the spent sorbent from the gas stream in the upstream collection section. An apparatus is also provided for performing the methods.

Abstract: The present invention provides a method and apparatus for removing trace contaminants from a gas stream or flue gas. In one embodiment, the present invention an apparatus for removing a trace contaminant from a gas stream, comprising a gas duct configured to receive a gas stream comprising a trace contaminant; a plurality of substrates disposed within the gas duct; a trace contaminant sorbent disposed on at least a portion of each of the substrates; an isolation device for separating the portion of each of the substrates from the gas stream; and a regenerator for regenerating the trace contaminant sorbent. In another embodiment, the present invention provides a method for removing a trace contaminant from a gas stream.

Abstract: A method for efficiently removing vapor-phase contaminants from gas streams is described. A powdered adsorbent such as activated carbon is ground into a fine powder by wet grinding to form a slurry. Chemicals are added to the slurry to impregnate the sorbent to enhance sorbent effectiveness. The slurry chemical mixture is sprayed into the gas stream in the form of small droplets which evaporate to produce an aerosol of fine adsorbent particles. Vapor-phase contaminants in the gas stream adsorb onto the fine adsorbent particle surfaces and the adsorbent particles are removed from the gas stream by a conventional particle collection method.

Abstract: A method of removing trace contaminants, such as mercury, from a flue gas by passing the gas over a sorbent structure on which is coated a renewable layer of sorbent. The sorbent structure can be a tube or plate and can be porous or non-porous and is placed inside a duct through which the flue gas flows. The sorbent particles comprise noble metal or activated carbon particles and can be injected into the gas stream before it passes over the sorbent structures. The sorbent structures can be periodically recoated with sorbent while the gas is still flowing.

Abstract: The present invention provides a method and apparatus for removing trace contaminants from a gas stream or flue gas. In one embodiment, the present invention an apparatus for removing a trace contaminant from a gas stream, comprising a gas duct configured to receive a gas stream comprising a trace contaminant; a plurality of substrates disposed within the gas duct; a trace contaminant sorbent disposed on at least a portion of each of the substrates; an isolation device for separating the portion of each of the substrates from the gas stream; and a regenerator for regenerating the trace contaminant sorbent. In another embodiment, the present invention provides a method for removing a trace contaminant from a gas stream.

Abstract: The present invention provides a method and apparatus for removing trace contaminants from a gas stream or flue gas. In one embodiment, the present invention an apparatus for removing a trace contaminant from a gas stream, comprising a gas duct configured to receive a gas stream comprising a trace contaminant; a plurality of substrates disposed within the gas duct; a trace contaminant sorbent disposed on at least a portion of each of the substrates; an isolation device for separating the portion of each of the substrates from the gas stream; and a regenerator for regenerating the trace contaminant sorbent. In another embodiment, the present invention provides a method for removing a trace contaminant from a gas stream.

Abstract: A process for removing vapor phase contaminants from a gas stream includes the step of adding a raw carbonaceous starting material into a gas stream having an activation temperature sufficient to convert the raw carbonaceous starting material into an activated material in-situ. The raw carbonaceous starting material can be either a solid-phase, liquid phase or vapor-phase material. The activated material then adsorbs the vapor phase contaminants, and the activation material containing the vapor phase contaminants is removed from the gas stream using a particulate collection device. The process is particularly suited for the removal of vapor phase air toxics, such as mercury, from the flue gas of a combustion process. An apparatus for the removal of vapor phase contaminants from a gas stream is also described.

Abstract: A method of treating flue gas includes the steps of generating a flue gas and removing particulate from the flue gas with a first particulate removal technique to produce treated flue gas. The treated flue gas is then applied to a high permeability barrier filter to remove additional particulate from the treated flue gas. The high permeability filter includes high permeability filter bags with air permeability greater than 75 actual cubic feet per minute of air flow per square foot of filter surface area at a pressure drop of one half inch water.

Abstract: The present invention provides a method and apparatus for removing trace contaminants from a gas stream or flue gas. In one embodiment, the present invention an apparatus for removing a trace contaminant from a gas stream, comprising a gas duct configured to receive a gas stream comprising a trace contaminant; a plurality of substrates disposed within the gas duct; a trace contaminant sorbent disposed on at least a portion of each of the substrates; an isolation device for separating the portion of each of the substrates from the gas stream; and a regenerator for regenerating the trace contaminant sorbent. In another embodiment, the present invention provides a method for removing a trace contaminant from a gas stream.

Abstract: The apparatus comprises a NOX reducing unit, a duct to receive a flue gas stream from said NOX and reducing unit, and an activation source associated with the duct. In use, the activation source applies energy to the flue gas stream to facilitate the removal of contaminants from the flue gas stream. Further, the method comprises providing an activation source is downstream of a NOX reducing unit. The activation source is then activated to facilitate the removal of contaminants from the flue gas stream.

Abstract: A process for removing vapor phase contaminants from a gas stream includes the step of adding a raw carbonaceous starting material into a gas stream having an activation temperature sufficient to convert the raw carbonaceous starting material into an activated material in-situ. The activated material then adsorbs the vapor phase contaminants, and the activation material containing the vapor phase contaminants is removed from the gas stream using a particulate collection device. The process is particularly suited for the removal of vapor phase air toxics, such as mercury, from the flue gas of a combustion process. An apparatus for the removal of vapor phase contaminants from a gas stream is also described.

Abstract: A method of removing trace contaminants, such as mercury, from a flue gas by passing the gas over a sorbent structure on which is coated a renewable layer of sorbent. The sorbent structure can be a tube or plate and can be porous or non-porous and is placed inside a duct through which the flue gas flows. The sorbent particles comprise noble metal or activated carbon particles and can be injected into the gas stream before it passes over the sorbent structures. The sorbent structures can be periodically recoated with sorbent while the gas is still flowing.

Abstract: A method of reducing NOX within a gas stream includes the step of placing a NOX reducing catalyst within a flue gas stream. The NOX reducing catalyst activity is enhanced by applying a separate activating source that significantly improves removal of NOX from the flue gas stream. The NOX reducing catalyst may be a stationary NOX reducing catalyst structure positioned in the flue gas stream. Alternately, the NOX reducing catalyst may be injected into the flue gas stream as a NOX reducing catalyst powder. The NOX reducing catalyst powder may be subsequently gathered in a particulate collection device. The NOX reducing catalyst may be further activated in the particulate collection device.

Abstract: An apparatus and method are described for removing vapor phase contaminants from a gas stream by placing a porous element having a sorbent material into ductwork through which the gas stream passes. In a first mode of operation, vapor phase contaminants are adsorbed by the sorbent. In a second mode of operation, the porous element is cleaned of any accumulated deposits, for example fly ash, while in place without having to stop the gas flow. In a third mode of operation, the sorbent can be regenerated in place and without having to stop the gas flow by heating and collecting the desorbed contaminants. This invention is particularly suited for the removal of vapor phase mercury from flue gas generated by a combustion process.