The present application pertains to methods for making metal oxides and/or citric acid. In one embodiment, the application pertains to a process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium. The process may include reacting a material comprising calcium carbonate and magnesium carbonate. Separating, concentrating, and calcining may lead to the production of oxides such as calcium oxide or magnesium oxide. In other embodiments the application pertains to methods for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt. Such processes may include, for example, reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution. Other useful steps may include desorbing, separating, and/or calcining.

The present application pertains to methods for making metal oxides and/or citric acid. In one embodiment, the application pertains to a process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium. The process may include reacting a material comprising calcium carbonate and magnesium carbonate. Separating, concentrating, and calcining may lead to the production of oxides such as calcium oxide or magnesium oxide. In other embodiments the application pertains to methods for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation—carboxylic acid anion salt. Such processes may include, for example, reacting an alkaline-earth cation—carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth—bisulfite and aqueous carboxylic acid solution. Other useful steps may include desorbing, separating, and/or calcining.

The present disclosure relates to a system and a method for removing noxious gas from cleaning liquid discharged from an exhaust gas treatment apparatus and, more particularly, to a system and a method for removing noxious gas from cleaning liquid discharged from an exhaust gas treatment apparatus, which are capable of adjusting the discharge rate of the cleaning liquid in a noxious gas removal unit, which removes noxious gas remaining in a gaseous state in the cleaning liquid discharged from the exhaust gas treatment apparatus and discharges the cleaning liquid from which the noxious gas in the gaseous state has been removed, on the basis of a result of measurement of the level of the cleaning liquid in the noxious gas removal unit.

A process for producing ethanol from lignocellulosic biomass includes adding at least one of sulfur dioxide and sulfurous acid to the lignocellulosic biomass to provide an equivalent sulfur dioxide loading of at least 10 wt % sulfur dioxide to dry lignocellulosic biomass. The acidified lignocellulosic biomass is pretreated at a temperature above about 185° C. and for a pretreatment time less than about 10 minutes, to provide a pretreated biomass composition wherein the biomass is readily hydrolyzed by enzymes. Advantageously, sulfur dioxide from at least one of the flash stream and a stream derived from the flash is recovered and recycled back into the process.

A flue gas denitration system includes a catalytic reactor accommodating a plurality of catalytic modules, into which a flue gas flows, and a flue gas heater provided on an upstream side of the catalytic reactor in a flow direction of the flue gas. In the flue gas denitration system, switched are a first denitration state in which the flue gas is denitrated by using the plurality of catalytic modules in the catalytic reactor and a second denitration state in which the flue gas is denitrated by using a catalytic module(s) less than those used in the first denitration state while a temperature of the flue gas flowing into the catalytic reactor is made higher than that in the first denitration state by using the flue gas heater. Thus, by making the temperature of the flue gas flowing into the catalytic reactor higher, it is possible to suppress deterioration in denitration performance in the case of using part of the plurality of catalytic modules for denitration.

The present disclosure relates to a system and a method for removing noxious gas from cleaning liquid discharged from an exhaust gas treatment apparatus and, more particularly, to a system and a method for removing noxious gas from cleaning liquid discharged from an exhaust gas treatment apparatus, which are capable of adjusting the discharge rate of the cleaning liquid in a noxious gas removal unit, which removes noxious gas remaining in a gaseous state in the cleaning liquid discharged from the exhaust gas treatment apparatus and discharges the cleaning liquid from which the noxious gas in the gaseous state has been removed, on the basis of a result of measurement of the level of the cleaning liquid in the noxious gas removal unit.

This disclosure provides a method for treating natural gas comprising causing at least some of a sour natural gas stream comprising hydrocarbon gas and hydrogen sulfide to contact an amine or pass through a separation system. A sweet natural gas stream comprising hydrocarbon gas and a waste gas stream comprising hydrogen sulfide are formed by contacting the sour natural gas with an amine or by passing it though a separation device. At least some of the hydrogen sulfide in the waste gas stream is oxidized, forming an exhaust gas stream comprising sulfur dioxide, which is then contacted with water or reactant and water solution or slurry to destroy or convert SO.sub.2 into a less environmentally harmful compound.

A method (200) for desulfurization of a flue gas in a desulfurization unit of an industrial plant, includes receiving (202) a plurality of baseline parameters corresponding to the desulfurization unit of the industrial plant. The method further includes measuring (204), using a stack sensor, an emission value of sulfur oxides in the flue gas. The method also includes estimating (208), using a controller, a desirable value of a slurry parameter for desulfurization of the flue gas based on the measured emission value of the sulfur oxides. The method further includes determining (208), using the controller, at least one desulfurization parameter based on the desirable value of the slurry parameter. The method also includes controlling (210), using the controller, operation of the desulfurization unit based on the at least one desulfurization parameter to modify consumption of at least one of a slurry and an auxiliary power in the industrial plant.

Oxygen is removed from a gas feed such as a landfill gas, a digester gas or an industrial CO.sub.2 off-gas by heating the feed gas, optionally removing siloxanes and silanols from the heated feed gas, optionally removing part of the sulfur-containing compounds in the heated feed gas, injecting one or more reactants for oxygen conversion into the heated feed gas, carrying out a selective catalytic conversion of any or all of the volatile organic compounds (VOCs) present in the gas, including sulfur-containing compounds, chlorine-containing compounds and any of the reactants injected, in at least one suitable reactor, and cleaning the resulting oxygen-depleted gas. The reactants to be injected comprise one or more of H.sub.2, CO, ammonia, urea, methanol, ethanol and dimethyl ether (DME).

Provided is an operation support system for a desulfurization apparatus evaluates soundness of the desulfurization apparatus by comparing an analytic performance calculated based on operation data of the desulfurization apparatus and a measured performance and creates support information including an operation condition candidate set based on the evaluation result and a balance forecast.