145 results about "Flue-gas stack" patented technology

An adsorbent composition for removing mercury from a flue gas stream, and a method of its use. The composition is a powdered activated carbon having at least one of a halogen-containing component and an alkaline component dispersed thereon. A flow agent can be composited with the material to maintain flowability in situ.

The invention presents a device for the removal of elemental mercury from flue gas streams utilizing a layer of activated carbon particles contained within the filter fabric of a filter bag for use in a flue gas scrubbing system.

Disclosed are apparatus and method to treat large amounts of flue gas from a pulverized coal combustion power plant. The flue gas is contacted with solid sorbents to selectively absorb CO₂, which is then released as a nearly pure CO₂ gas stream upon regeneration at higher temperature. The method is capable of handling the necessary sorbent circulation rates of tens of millions of lbs/hr to separate CO₂ from a power plant's flue gas stream. Because pressurizing large amounts of flue gas is cost prohibitive, the method of this invention minimizes the overall pressure drop in the absorption section to less than 25 inches of water column. The internal circulation of sorbent within the absorber assembly in the proposed method not only minimizes temperature increases in the absorber to less than 25° F., but also increases the CO₂ concentration in the sorbent to near saturation levels. Saturating the sorbent with CO₂ in the absorber section minimizes the heat energy needed for sorbent regeneration. The commercial embodiments of the proposed method can be optimized for sorbents with slower or faster absorption kinetics, low or high heat release rates, low or high saturation capacities and slower or faster regeneration kinetics.

A preferred apparatus arrangement utilizes the enthalpy of the flue gas, which can be supplemented if need be, to convert urea (30) into ammonia for SCR. Urea (30), which decomposes at temperatures above 140.degree. C., is injected (32) into a flue gas stream split off (28) after a heat exchanger (22), such as a primary superheater or an economizer. Ideally, the side stream would gasify the urea without need for further heating; but, when heat is required it is far less than would be needed to heat either the entire effluent (23) or the urea (30). This side stream, typically less than 3% of the flue gas, provides the required temperature and residence time for complete decomposition of urea (30). A cyclonic separator can be used to remove particulates and completely mix the reagent and flue gas. This stream can then be directed to an injection grid (37) ahead of SCR using a blower (36). The mixing with the flue gas is facilitated due to an order of magnitude higher mass of side stream compared to that injected through the AIG in a traditional ammonia-SCR process.

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.

A system for removing particulate, sulfur dioxide, nitrogenous oxides and other condensables from the flue gas of a coal, lignite, or other solid fuel combustor. The system can combine biomass filtration, anaerobic digestion, steam absorption refrigeration, and heat exchangers to minimize parasitic energy consumption, solid and liquid waste disposal and interference with combustion efficiency, while achieving near total reduction of contaminants without regard to sulfur or ash content of fuel. Gases at the exit of a multiclone of a fuel-combustor enter a waste heat boiler, generating low pressure steam that drives a steam absorption chiller. The flue gas which still contains small particulate material pass through a moving belt system conveying a mat of chopped biomass that can be impregnated with bacteria that feed on nitrogenous oxides. The mat is sufficiently thick and moist to entrap the remaining solids and smoke in the exhaust stream. The particulate-free flue gas passes through a staged heat exchanger which can utilize ambient air, pond water, and the refrigerated water from the steam absorption chiller to condense the water vapor in the exhaust stream. Sulfur oxides exits the flue gas stream with the condensed water vapor which can be processed in an anaerobic digester. Methanogenic bacteria within the digester can convert the mat and the acidic condensate into a biogas, a combination of methane and carbon dioxide, and plant growth media.

One aspect of the invention relates to a method for removing contaminants from a flue gas stream (22). The method includes: removing fly ash from a flue gas stream (22) utilizing a particle collector (24); contacting the flue gas stream with an alkaline reagent in a wet scrubber (26); discharging a purge liquid (30) from the wet scrubber (26); combining at least a portion of the purge liquid (30) with at least a portion of the fly ash (48) to form moistened fly ash (60); and injecting at least a portion of the moistened fly ash (60) into the flue gas stream (22) upstream of the particle collector (24), whereby the moistened fly ash (60) removes at least a portion of contaminants present in the flue gas stream (22).

The present invention relates to a cylindrical spraying tower for eliminating the sulfur dioxide in the flue gas and a method for eliminating the sulfur dioxide in the flue gas with the spraying tower thereof, wherein the spraying tower is provided with two vertical clapboards and is provided with a defroster at the outlet, the clapboard is provided with an opening thereby dividing the absorbing area to three areas and dividing the serous fluid tank into two sections. The flue gas contacts with the spraying serous fluid concurrently and then countercurrent in the area of the absorbing area and is discharged through the defroster. The excellent desulfurizing effect is realized and the method is especially suitable for the wet limestone gypsum flue gas desulfurization technique of the large-scale thermal power plant with the power more than 300MW.

The present invention provides a method of scrubbing SOx, NOx compounds and other air toxins from a flue gas stream. In the method, two distinct unit operations are amalgamated to scrub SOx, NOx and other air toxins compounds from a flue gas stream. More specifically, there is a dry scrubbing operation and a wet scrubbing operation. The dry injection scrubbing operation involves contacting a flue gas stream containing SOx and NOx compounds with a sorbent for removing substantially all of the SOx and NOx compounds present in the stream. The second wet scrubbing operation involves contacting the stream to remove any residual SOx, NOx compounds, and other air toxins remaining in the stream.

The invention relates to a continuous pyrolysis incineration device for full-scale electronic and electrical product waste. The continuous pyrolysis incineration device structurally comprises a feeder, a pulley feed hopper, a pyrolysis gasifier, a pyrolysis gas flue, a combustion furnace, a G-L air heat exchanger, a quenching absorption tower, a bypass flue, a chimney exhaust port, a cat ladder, an activated carbon storage tank and a chimney. The continuous pyrolysis incineration device has the advantages that dangerous electronic and electrical product waste, medical waste, organic waste and other kinds of dangerous combustible solid waste with a certain heat value are treated through a pyrolysis incineration technology, pyrolysis and high-temperature incineration technologies are combined in an optimized mode, low-temperature gas and high-temperature melt are combined together, waste incineration is conducted in the steps of pyrolysis, premixing and incineration, the synthetic technological process and technological conditions of pyrolysis incineration, energy recovery and flue gas cleaning are achieved and have perspectiveness, the overall technology has the outstanding harmless characteristic, compatibility and resourcezation are remarkable, material applicability is high, no hazardous reaction medium or poisonous and harmful solvent is involved in the process, and nature greenization can be achieved.

Combustion flue gas containing NO_X and SO_X is treated to remove NO_X in a multistep system in which NO_X is reduced in the flue gas stream via selective catalytic reduction or selective non-catalytic reduction with ammonia or an ammonia-forming compound, followed treatment with hydrogen peroxide to remove residual ammonia and, optionally, treatment with an alkali reagent to reduce residual NO_X in the flue gas stream. The NO_X-depleted flue gas stream may also be subjected to a desulfurization treatment for removal of SO_X.

Pollutants in a flue gas stream from a dryer of products, such as wood chips, are removed by a pollution abatement system that includes an electrified filter bed unit for removing solid particulates. To prevent deteriorated operation of the electrified filter bed unit due to condensation of volatile organic compounds, the flue gas stream is heated, prior to admission to the electrified filter bed unit, to a temperature sufficient to convert condensable liquid aerosols to a gaseous state. The electrified filter bed unit then removes solid particulate selectively without collecting condensable organics. After the flue gas stream has passed through the electrified filter bed unit, gaseous pollutants can be removed by an oxidation process, for example.

Combustion flue gas containing SO_X is treated to remove SO_X using a dry particulate sorbent injection procedure in which a sodium-based sorbent precursor is calcined immediately prior to its introduction into the flue gas stream, to activate the sorbent for reaction with SO_X. The sorbent precursor is a NaHCO₃-containing compound, and trona is preferred as the sorbent precursor.

An improved flue gas sensor of a combustion device is disclosed. The flue gas sensor may include a housing and a gas detector disposed within the housing, wherein the gas detector detects or measures at least one gas in a flue gas stream of the combustion device. The housing may also include a water barrier member through which the at least one gas comes into contact with the gas detector. By keeping water and water vapor away from the gas detector, premature failure of the flue gas sensor caused by corrosion may be prevented.

The invention discloses a method for recovering selenium, mercury, gold and silver from acid sludge. The method comprises the steps: (1) putting the acid sludge, generated from a sulfide ore roasting flue gas acid preparing process, into a tubular furnace, and carrying out roasting treatment under the condition of a protective atmosphere, so as to obtain roasting slag and flue gas containing gaseous mercury selenide; (2) cooling the flue gas, so as to cool the gaseous mercury selenide in the flue gas into solid-state mercury selenide and recover selenium and mercury from the acid sludge; (3) extracting gold and silver from the roasting slag obtained in the step (1) by adopting a cyanidation method, so as to recover gold and silver from the acid sludge. According to the method, the solid-state mercury selenide with high added value is obtained by adopting a protective atmosphere roasting process, and gold and silver are recovered by adopting the cyanidation method, so that the method has the advantages of brief flow, high product added value, high purity, high valuable element recovery ratio and little environmental pollution.

A method of removing SO3 from a flue gas stream having increased amounts of SO3 formed by a NOx removal system, includes injecting a sorbent composition into the flue gas stream. The sorbent composition includes an additive and a sodium sorbent such as mechanically refined trona or sodium bicarbonate. The additive is selected magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, and mixtures thereof. The concentration of the SO3 in the flue gas stream is reduced and the formation of a liquid phase NaHSO4 reaction product is minimized.