A method for reducing carbon dioxide to manufacture a multi-carbon hydrocarbon compound includes steps as follows. A reduction reaction with separation and purification system is provided, which includes a carbon dioxide absorption tower, a reactor, a gas-liquid separation device, a liquid-phase purification device and a gas-phase purification device. An absorption step is performed, wherein a carbon dioxide gas is absorbed to form a mixed solution. A photocatalysis step is performed, wherein the mixed solution is reacted with a photocatalyst to form a carbon-based compound. A separation step is performed, wherein the carbon-based compound is separated to form a liquid-phase mixture and a gas-phase mixture. A liquid-phase purification step is performed, wherein the liquid-phase mixture is purified. A gas-phase purification step is performed, wherein the gas-phase mixture is separated and purified to form a multi-carbon hydrocarbon compound.

An apparatus for purifying gas where gas is treated in a multistage treatment having at least two ejector stages, a motive medium including liquid, steam or gaseous agent at high pressure injected by an ejector of the ejector stage, and the gas is sucked into the same ejector and mixed with the motive medium for forming a mixture, at least a part of gas and/or liquid phase of the mixture is supplied to a second ejector stage having so that a second motive medium which includes liquid, steam or gaseous agent is injected to the ejector and the gas and/or the liquid phase is sucked into the same ejector in which the gas and/or liquid phase is mixed with the second motive medium for forming a second mixture, at least one of the mixtures includes an additive for removing impurities of the gas, and a purified gas is formed.

An apparatus is disclosed including a desulfurization device which removes sulfur oxides contained in boiler flue gas, a spray drying device which sprays desulfurization waste water discharged from the desulfurization device and which dries the waste water by introducing a drying gas, a flue gas supplying line L.sub.13 which returns, to a main flue L.sub.11, flue gas obtained after the desulfurization waste water is evaporated and dried, an alkaline agent supplying unit which adds an alkaline agent to a desulfurization waste water line L.sub.21, and a pH meter which measures the pH in the desulfurization waste water at locations before and after the alkaline agent supplying unit in the desulfurization waste water line L.sub.21, wherein the alkaline agent is added in accordance with a measurement result of a measured pH to cause the desulfurization waste water added with the alkaline agent to have a pH fall within a predetermined pH.

Methods and systems for producing aromatics and light olefins from a mixed plastics stream are described. The method may include feeding a plastic feedstock to a dechlorination operation to melt the plastic feedstock to release HCl and generate a liquid plastic stream; feeding the liquid plastic stream to a pyrolysis reactor, the pyrolysis reactor to generate hydrocarbon vapors; feeding the hydrocarbon vapors to an acid gas removal reactor with a solid inorganic alkali salt disposed within the reaction vessel to remove residual HCl and sulfur-containing compounds from the hydrocarbon vapors to generate a plastic derived oil; and feeding the plastic derived oil to a steam enhanced catalytic cracking reactor to generate a product stream comprising light olefins having a carbon number of C.sub.2-C.sub.4 and aromatics. The associated system for processing mixed plastics into aromatics and light olefins is also described.

Methods and systems for producing aromatics and light olefins from a mixed plastics stream are described. The method may include feeding a plastic feedstock to a dechlorination operation to melt the plastic feedstock to release HCl and generate a liquid plastic stream; feeding the liquid plastic stream to a pyrolysis reactor, the pyrolysis reactor to generate hydrocarbon vapors; feeding the hydrocarbon vapors to an acid gas removal reactor with a solid inorganic alkali salt disposed within the reaction vessel to remove residual HCl and sulfur-containing compounds from the hydrocarbon vapors to generate a plastic derived oil; and feeding the plastic derived oil to a fluid catalytic cracking reactor to generate a product stream comprising light olefins having a carbon number of C.sub.2-C.sub.4 and aromatics. The associated system for processing mixed plastics into aromatics and light olefins is also described.

A desulfurization gas process includes water vapor, CO.sub.2 and SO.sub.x (x=2 and/or 3). In a treatment unit, the gas contacts a cooled alkaline aqueous solution having a temperature lower than an initial gas temperature, water and a carbonate of an alkali metal, to cool the gas, condense some water vapor and absorb SO.sub.x in the carbonate-containing solution, produce an SO.sub.x-depleted gas and an acidic aqueous solution including sulfate and/or sulfite ions. The SO.sub.x-depleted gas and a portion of the acidic aqueous solution can then be withdrawn from the treatment unit. Carbonate of the alkali metal can be added to remaining acidic aqueous solution to obtain a made-up alkaline aqueous solution. This solution can be cooled and reused as the cooled alkaline aqueous solution. An SO.sub.x absorbent solution includes a bleed stream from a CO.sub.2-capture process, sodium or potassium carbonate, and an acidic aqueous solution obtained from desulfurization.

Disclosed is a compact venturi scrubber, used for removing undesirable materials from a gas stream, that includes a gas inlet section, a discharge section aligned with the gas inlet section, the discharge section having a base defined by the intersection of the gas inlet section and the discharge section, a diverging interior surface, and a diverging angle defined by the diverging interior surface, a nozzle, and a liquid inlet through which a liquid scrubbing medium is introduced to the nozzle, wherein the nozzle produces a full spray pattern directed towards the base of the discharge section with a sufficiently large discharge angle so that a cross-sectional area of the full spray pattern produced by the nozzle at the point it intersects with the base of the discharge section fully covers, and substantially matches the size and shape of, the cross-sectional area of the base of the discharge section.

A method and system for reducing ion concentration of a solution and converting gas. The system comprising a multi-chamber unitary dialysis cell comprising a gas chamber, a product chamber, and an acid chamber. Ion exchange barriers separate the chambers of the dialysis cell. A first anion exchange barrier is positioned between the product chamber and the acid chamber and a first cation exchange barrier is positioned between the product chamber and the gas chamber. Anions from the solution being treated associate with cations from the acid chamber to form an acid solution in the acid chamber, and cations from the solution being treated associate with anions from the fluid comprising gas to form salt, thereby reducing the ion concentration of the solution being treated and converting at least a portion of the gas into salt.

The invention pertains to methods of reducing dissolved elements such as arsenic, selenium and mercury in aqueous solutions using, for example, various barium compounds to partition said elements to a solid phase. Such methods are particularly useful for reducing such elements at various points in coal and oil-fired power plants prior to final waste water treatment.

A method and system for electrochemically regenerating hydroxide (MOH) and carbon dioxide (CO.sub.2) from an alkali metal carbonate (M.sub.2CO.sub.3) via an electrochemical reactor that can replace a conventional thermochemical causticizing operation in a DAC system. The electrochemical reactor comprises: a cathode having an inlet for receiving an electrolyte feed stream comprising MOH, M.sub.2CO.sub.3 and H.sub.2O, and an outlet for discharging an electrolyte product stream comprising MOH, M.sub.2CO.sub.3, H.sub.2O and H.sub.2; a porous hydrophilic transport barrier in adjacent contact with the cathode; a porous hydrophilic anode in adjacent contact with the transport barrier configured and operable to generate CO.sub.2 in the presence of MOH while suppressing their recombination; a porous hydrophobic CO.sub.2 and O.sub.2 separation barrier in adjacent contact with the anode; and a product gas exit channel in adjacent contact with the CO.sub.2 and O.sub.2 separation barrier and for discharging an anode product stream comprising at least CO.sub.2.