Described herein are membrane processes for separating CO.sub.2 from flue gas. An exemplary process involves passing a fluid stream including the flue gas across a membrane permeable to CO.sub.2 and H.sub.2O, removing treated gas from a feed side of the membrane that has less CO.sub.2 than the flue gas, and removing permeate from a permeate side of the membrane comprising CO.sub.2 and H.sub.2O. Suitably, the permeate is removed at a sub-atmospheric vacuum pressure. The permeate is then cooled to remove at least some of the H.sub.2O from the permeate and form a smaller volume of H.sub.2O-depleted, CO.sub.2 enriched permeate.

A cement clinker producing system, capable of providing a gas containing a carbon dioxide gas at a high concentration by increasing a carbon dioxide gas concentration for a part of an exhaust gas, includes a cyclone preheater to preheat a cement clinker raw material, a rotary kiln to burn the preheated cement clinker raw material so as to provide cement clinker, a calcination furnace to promote decarbonation of the cement clinker raw material, a clinker cooler to cool the cement clinker, a kiln exhaust-gas discharge passages to discharge an exhaust gas generated in the rotary kiln, a combustion-supporting gas supply device to supply a combustion-supporting gas having a higher oxygen concentration than air, a combustion-supporting gas supply passage to guide the combustion-supporting gas to the calcination furnace, and a calcination furnace exhaust-gas discharge passage to discharge a carbon dioxide gas-containing exhaust gas generated in the calcination furnace.

Methods of sequestering carbon dioxide (CO.sub.2) are provided. Aspects of the methods include contacting an aqueous capture ammonia with a gaseous source of CO.sub.2 under conditions sufficient to produce an aqueous ammonium carbonate. The aqueous ammonium carbonate is then combined with a cation source under conditions sufficient to produce a solid CO.sub.2 sequestering carbonate and an aqueous ammonium salt. The aqueous capture ammonia is then regenerated from the from the aqueous ammonium salt. Also provided are systems configured for carrying out the methods.

The invention relates to a method for reduction of HCl emission from a cement plant based on a treatment of a preheater (1) and/or bypass gas stream, characterized in that a cement raw meal, as a HCl absorber, is dispersed in the gas stream(s) from which HCl is to be removed; the cement raw meal is introduced from a raw mill (6) and/or a silo (8) into a pipe with a up going gas flow; the pipe being arranged in fluid communication at a point after a gas conditioning tower (7) and/or before a particle filter unit (5) and/or in a by-pass line before particle filter (4).

Provided herein are methods of removing carbon dioxide from an aqueous stream or gaseous stream by: contacting the gaseous stream comprising carbon dioxide, when present, with an aqueous solution comprising ions capable of forming an insoluble carbonate salt; contacting the aqueous solution comprising carbon dioxide with an electroactive mesh that induces its alkalinization thereby forcing the precipitation of a carbonate solid from the solution and thereby the removal of dissolved inorganic carbon by electrolysis; and removing the precipitated carbonate solids from the solution, or the surface of the mesh where they may deposit. Also provided herein are flow-through electrolytic reactors comprising an intake device in fluid connection with a rotating cylinder comprising an electroactive mesh, and a scraping device and/or liquid-spray based device for separating a solid from the mesh surface.

Method and installation for treating a CO.sub.2- and H.sub.2O-containing flue gas generated by an industrial process unit before CCUS, whereby the flue gas evacuated from the unit is subjected to cooling to a temperature T2 between 100 and 600° C., whereby the cooled flue gas is pretreated in one or more particle removal and/or gas cleaning and/or drying stages and the temperature of the cooled flue gas is further reduced to a temperature T3<T2, before a first part of pretreated flue gas is subjected to CCUS, a second part of the pretreated flue gas being recycled at temperature T3 as a cooling agent and mixed with the flue gas during the controlled cooling thereof, partially or fully purified CO.sub.2 from the CCUS may be recycled at temperature T4<T2 may be recycled as a cooling agent and mixed with the flue gas during the controlled cooling.

An apparatus includes a housing that defines a first zone, a second zone, a third zone, and a fourth zone. The apparatus includes an inlet, a first outlet, a second outlet, and a conveyor belt. The inlet is configured to receive a carbon dioxide-containing fluid in the first zone. The first outlet is configured to discharge a carbon dioxide-depleted fluid from the first zone. The second outlet is configured to discharge a carbon dioxide-rich fluid from the third zone. The conveyor belt passes through each of the zones. The conveyor belt includes a carbon dioxide sorbent. Within the first zone, the carbon dioxide sorbent is configured to adsorb carbon dioxide from the carbon dioxide-containing fluid to produce the carbon dioxide-depleted fluid. Within the third zone, the carbon dioxide sorbent is configured to desorb the captured carbon dioxide to produce the carbon dioxide-rich fluid.

The removal of acid gases (e.g., non-carbon dioxide acid gases) using sorbents that include salts in molten form, and related systems and methods, are generally described.

A method for reducing pollution in exhaust gases and a system for treating exhaust gas are provided. The method includes the step of treating an exhaust gas stream with a treating fluid. In one application, the treating fluid is injected by spraying droplets into the exhaust gas stream. A system for treating exhaust gas includes a reagent, and a nozzle to spray the reagent into the exhaust gas stream.

Techniques for drift elimination in a liquid-gas contactor system include configuring a pre-fabricated mechanical frame coupled to a drift eliminator material to produce a framed drift eliminator assembly with substantially no air gaps between the drift eliminator material and the pre-fabricated mechanical frame, and coupling the framed drift eliminator assembly to the liquid-gas contactor system.