84 results about "Mercury oxidation" patented technology

In a method for removing mercury from flue gas produced by combustion devices burning coal and other fuels that contain mercury and chlorine the combustion process is controlled to generate a flue gas comprising fly ash containing at least 0.25% unburned carbon, and preferably at least 5.0% unburned carbon. In addition the flue gas is rapidly cooled from a temperature within the range of 1450° F. to 900° F. to a temperature below 900° F. at a rate of at least 1000° F. per second. This step will enhance the concentrations of Cl-atoms and Cl₂, which accelerates the rates of mercury oxidation in both the gas phase and on particle surfaces. Finally, the flue gas is directed to the particle removal device for removal of the fly ash to which some of the mercury is bound, and also directed to a wet scrubber for retention of the oxidized mercury vapor in wastewater and solid effluents.

The present invention provides a system for removing mercury in exhaust gas, in which mercury is removed from exhaust gas of a boiler, characterized in that between a denitrification apparatus and a wet type desulfurization apparatus, an NH₃ decomposition catalyst and a mercury oxidation catalyst are provided, and mercury having been oxidized into mercury chloride is removed by the wet type desulfurization apparatus. Also, it provides a method for removing mercury in exhaust gas, characterized in that the mercury removing method includes an NH₃ decomposition process and a mercury oxidation process, which are provided between the denitrification process and a wet desulfurization process, and mercury having been oxidized into mercury chloride is removed in the wet desulfurization process.

The invention discloses a copper-based composite catalyst for gas-state zero valent mercury oxidation in the field of smoke control and a preparation method and the purpose thereof. The copper-based catalyst is a copper-based composite oxide catalyst and/or a copper-based composite halide catalyst. The catalyst can utilize oxygen and trace HCI existing in smoke to achieve high efficiency conversion of zero valent mercury (HgO) and divalent mercury (Hg2+) under low temperature in a wider temperature range (500-300 DEG C) and can even achieve high efficiency oxidation of simple substance mercury in smoke free of HCI. The catalyst is suitable for catalytic oxidation of mercury in fire coal smoke, and the product Hg2+ of oxidation can be easily dissolved in water and can be removed by other pollutant control devices. The catalyst is simple in preparation method, wide in suitable temperature range, high in oxidation efficiency, weak in dependency on CI in the smoke, good in stability and high in SO2 poisoning resistance and has good application prospects and economical benefits in the fire coal smoke mercury discharge control fields including power station boilers, industrial boilers, industrial kilns and the like.

The invention discloses flue gas mercury absorption liquid with functions of oxidizing and fixing, which consists of calcium-based desulphurization slurry, Fenton reagent and soluble thiosulfate. The Fenton reagent is used as oxidant to oxidize zero-state mercury, and the thiosulfate is used as a stabilizing agent to precipitate and stabilize the absorbed mercury. The precipitated mercury and the generated gypsum are precipitated together to form a solid phase, a part of the absorbed sulfur dioxide is absorbed into a liquid phase and oxidized into gypsum under the action of redundant oxidant, the absorption liquid separates the gypsum from the liquid phase through solid-liquid separation modes such as precipitation and the like, and the mercury is separated and removed at the same time. The mercury absorption liquid of the invention can be used for flue gas purification, and has the capacities of mercury oxidation absorption and liquid phase stabilization.

A filter contains a textile having on at least one side a plurality of treated activated carbon particles. The treated activated carbon particles contain a plurality of activated carbon particles, a hydrophobic agent, a mercury oxidation facilitation agent, and optionally a binder.

The invention discloses a method and device for the collaborative removal of mercury in flue gas, and belongs to the purification field of the flue gas in atmospheric pollutants of power plant boilers. The method comprises the following steps that: after primary hot air or secondary hot air of a temperature boiler is introduced to mix with a mercury removal oxidant and an SCR (selective catalytic reduction) denitration reductant, and then the flue gas is injected to mix again, an obtained mixture enters an SCR denitration device to denitrate along a flow path of the flue gas, and simultaneously, elemental mercury Hg0 is oxidated into gaseous bivalent mercury oxide Hg<2+>; then, the gaseous bivalent mercury oxide Hg<2+> enters a dust remover to carry out dust removal, and simultaneously, granular mercury Hg is removed; and then, the obtained product is subjected to desulfurization in a wet flue gas desulfurization device, and simultaneously, the bivalent mercury oxide Hg<2+> is removed. The device comprises an SCR denitration system, and a device for mixing hot air, a mercury removal oxidant and the SCR denitration reductant. The method and the device for the collaborative removal of the mercury in the flue gas, disclosed by the invention, fully use the collaborative function of the existing SCR denitration system, the dust remover and the WFGD (wet flue gas desulfurization device), and are few in system changes and good in mercury removal effect.

Disclosed is a novel demercuration catalyst. As mercury has extremely high accumulation performance in the environment and in organisms, it has very strong toxicity for mankind and wild animals and plants even the concentration is very low. In recent years, mercury is considered as another pollution problem in the world. Present existing demercuration catalysts have disadvantages of poor anti-poisoning capability and high cost, and are difficult to realize industrialization. In order overcome these advantages, a novel demercuration catalyst is invented. The product is prepared from TOx (T is Cu, Fe and V) and ROy (R is La and Ce) with the addition of titanium dioxide pillared montmorillonite. The invention belongs to the technical field of separation. The demercuration catalyst can be used for elemental mercury removal from flue gas. The invention is characterized in that the catalyst has high mercury adsorption capability and mercury oxidation catalysis capability. The catalyst has very strong anti-poisoning capability.

The present invention provides a method for removing mercury in exhaust gas, in which mercury in exhaust gas discharged from combustion equipment is removed, characterized by including a mercury oxidation process in which mercury in the exhaust gas is converted to mercury chloride in the presence of a catalyst; a contact process in which the exhaust gas is brought into contact with an absorbing solution in a scrubber to absorb and remove mercury components from the exhaust gas; and a control process in which blowing of air or addition of an oxidizing agent into the scrubber is accomplished, and the amount of blown air or the added amount of oxidizing agent is regulated to control the oxidation-reduction potential of the absorbing agent, and a system for removing mercury in exhaust gas. According to the mercury removing method in accordance with the present invention, a phenomenon that mercury chloride is reduced into metallic mercury by SO₂ etc. and the metallic mercury scatters in the exhaust gas can be prevented, and mercury in the exhaust gas can be decreased effectively.

A flue gas treatment system and a flue gas treatment method capable of drastically reducing operating cost and an amount of waste water and capable of controlling an amount of a NOx reducing agent and a mercury oxidation agent to be supplied are provided. The flue gas treatment system sprays an aqueous solution containing ammonium halide into a flue, reduces NOx and oxidizes mercury in a deNOx section, and removes SOx and the mercury in a desulfurization section. The flue gas treatment system adds at least one of ammonium sulfate and ammonium carbonate to waste water which is discharged from the desulfurization section and from which CaSO₄ is separated to generate the ammonium halide. The waste water containing the ammonium halide is sprayed as the aqueous solution.

The invention discloses a method for oxidizing elemental mercury by improving a gas selective catalytic reduction (SCR) denitration processing system, wherein a traditional SCR catalyst layer is distributed in front of a mercury oxidation catalyst, and 1-2 layers of modified SCR catalysts are further distributed. A method for preparing a modified SCR catalyst is that predecessors of V2O5 and WO3 are added in the preparation of a SCR catalyst of V2O5-WO3/TiO2, and cerous nitrate, cupric nitrate or cobalt nitrate is further added at the same time, and the oxidation efficiency of mercury in gas is above 80%. The method for oxidizing the elemental mercury by improving the gas SCR denitration processing system has the advantages that the method for oxidizing the elemental mercury by improving the gas SCR denitration processing system does not need to improve equipment based on an original gas SCR denitration processing system, does not need to use additional additives, does not need to be further provided with mercury removal equipment, and achieves to effectively denitration and mercury oxidation by utilizing the SCR catalyst and the modified SCR catalyst. Simultaneously, the method for oxidizing the elemental mercury by improving the gas SCR denitration processing system prevents the influence of NH3 to mercury oxidation by reasonably arranging the SCR catalyst and the modified SCR catalyst, thereby improving mercury discharge efficiency.

A method for oxidizing elemental mercury contained in flue gas uses a catalytic barrier filter. The method comprises directing the flue gas towards the catalytic barrier filter; passing the flue gas through the catalytic barrier filter in the presence of an oxidant; and outletting the flue gas from the catalytic barrier filter, wherein about 50 percent to about 99 percent of the elemental mercury is oxidized.

A catalyst is provided having higher mercury oxidation performance than a conventional catalyst without increasing catalyst quantity or enhancing SO₂ oxidation performance and constitutes an oxidation catalyst for metal mercury, which contains a molybdenum and vanadium complex oxide, for example, MoV₂O₈, as a main component having a catalytic activity and is formed by placing the molybdenum and vanadium complex oxide in layers only on the surface of a plate-like or honeycomb-like porous carrier. The porous carrier contains Ti and W and has a function of an NOx removal catalyst as a whole.

The invention relates to a composite catalyst based on a denitration and demercuration reinforcing function of prepositive SCO smoke of a coal-fired power plant and a preparation method thereof. Main active ingredients of the composite catalyst are Co3O4 and CuCl2, and a carrier ingredient is Ce-doped TiO2. The preparation method includes: adopting a sol-gel method to prepare a Ce-doped TiO2 carrier, adopting an impregnation method to sequentially load Co3O4 and CuCl2. A selective catalytic oxidation unit using the catalyst as a main body is arranged at the front end of an SCR unit, oxidation of Hg0 does not be influenced by the ammonification process of the SCR unit, and high mercury oxidation removing efficiency can be realized in a chlorine-free condition. In addition, the catalyst can convert part of NO into NO2 while efficiently oxidizing Hg0, so that reaction efficiency of subsequent SCR process is improved remarkably. The catalyst is easy-to-get in raw material, simple in preparation method, easy-to-implement in technical process and conducive to industrial application.

The invention discloses a cerous phosphate based catalyst for zero-valent mercury oxidation. The catalyst is mainly composed of cerous phosphate, and comprises modification components; wherein the modification components are composed of at least one oxide of cobalt, manganese, copper, iron, vanadium, cerium, molybdenum, tin, and the like. The invention also discloses a preparation method and applications of the catalyst. The preparation process is simple, and the operation is convenient. Compared to the prior art, the catalyst has the following advantages: (1) the active components of the catalyst are all common metal oxides, the common metal phosphate is taken as the carrier, the raw materials are simple and easily available, and the operation is convenient; (2) the catalyst has a very good sulfur-resistant performance; (3) the CePO4 catalyst, which has been modified by metal oxides, is well adapt to the flue gas. The provided catalyst can fully utilizes the NO in flue gas to greatly promote the oxidation of zero-valent mercury. The great dependence on HCl of conventional catalysts is gotten rid of.

The invention discloses a device for removing gas mercury by photo-catalysis, which adopts the method for loading nanometer TiO2-SiO2 on fibers of a titanium mesh and installing a UV ultraviolet source on the middle part. The gaseous mercury passing through the fibers of the titanium mesh is oxidized as Hg2+ through arranging multi-branched double-cylinder pipe which can be detached in sections in a gas duct, and then the gaseous mercury can be removed through the lime slurry of equipment for removing sulfur by wet process. The reaction sections of the device for removing the gas mercury by photo-catalysis in the invention are separately connected, so the reaction sections can be conveniently detached and changed, the removing efficiency is over 60%, and the economical efficiency is good. Simultaneously the complete device has the advantages of little taken space and good economical efficiency, and the device can be conveniently detached and changed. The device can be applied to the relative fields of removing the gas mercury from power plants, industrial boilers and coal combustion facilities, and has wide prospect on popularization and application of environmental mercury pollution treatment technology.

The invention relates to a preparation method of a composite high-activity demercuration adsorbent, and belongs to the technical field of an demercuration adsorbent. Straw fly ash is subjected to acid soaking modification and is then subjected to soaking modification by copper chloride solution, so that the modified fly ash has good adsorbability; after the treatment and modification on attapulgite, copper oxide is loaded on the attapulgite, so that the loaded attapulgite has good catalyst performance; the mercury oxidation rate is improved. The demercuration adsorbent prepared by the invention has high oxidization rate on mercury and good adsorption rate; physical adsorption and chemical adsorption are combined, so that the demercuration activity is high; compared with the conventional active carbon, the high-activity demercuration adsorbent has the advantages of high mercury adsorption capability and long effective adsorption time.

The invention discloses a denitration, demercuration and dioxin removal catalyst and a preparation method thereof. According to the catalyst, a molecular sieve is adopted as a first carrier; titaniumdioxide is adopted as second carrier; cerium, tin and palladium are used as a first active component; vanadium, zirconium, neodymium and cobalt are used as second active components; two or more of molybdenum, yttrium, silver, lanthanum and nickel are used as cocatalysts; one or more of polyvinyl alcohol, carboxymethyl cellulose, liquid paraffin, ammonium polyacrylate, hydroxypropyl methyl cellulose or amino cellulose are used as forming auxiliaries; catalyst paste is prepared, and the flat plate type denitration catalyst is prepared through aging, coating, drying, shearing and calcining. The prepared catalyst has excellent denitration performance, mercury oxidation performance and dioxin removal performance at 180-400 DEG C, has good sulfur resistance and water resistance, and is suitablefor synergistic removal of coal-fired power plants, waste incineration power plants, steel sintering machines, glass kilns and the like.