The disclosure provides seven integrated methods for the chemical sequestration of carbon dioxide (CO.sub.2), nitric oxide (NO), nitrogen dioxide (NO.sub.2) (collectively NO.sub.x, where x=1, 2) and sulfur dioxide (SO.sub.2) using closed loop technology. The methods recycle process reagents and mass balance consumable reagents that can be made using electrochemical separation of sodium chloride (NaCl) or potassium chloride (KCl). The technology applies to marine and terrestrial exhaust gas sources for CO.sub.2, NOx and SO.sub.2. The integrated technology combines compatible and green processes that capture and/or convert CO.sub.2, NOx and SO.sub.2 into compounds that enhance the environment, many with commercial value.

The present invention discloses a process for preparing sulfur from reduction of sulfate/nitrate by iron-carbon and recovering desulfurization/denitration agents. High-concentration SO.sub.2 flue gas produced by calcination of a sulfate and NOx produced by heating decomposition of a nitrate can be directly reduced to elemental sulfur vapor and N.sub.2 through reaction with an iron-carbon material at a high temperature. Then, after dust removal, cooling and fine dust removal, sulfur is recovered by a sulfur recovery device, and metal oxides can replace alkaline mineral resources such as limestone as raw materials of desulfurization (denitration) agents. This process can recycle the desulfurization and denitration agents.

The present disclosure provides an automatic control system for emission indexes of a desulfurization device of a thermal power unit, which comprises a first controller, a second controller and a flow controller. At the same time, the present disclosure provides an automatic control method for emission indexes of a desulfurization device of a thermal power unit. The present disclosure runs through the production and operation data of waste gas desulfurization treatment facilities, and establishes a pH optimization set value prediction model according to the data, and can realize automatic regulation and control of pH value by optimizing and controlling the pH optimization set value and the slurry flow optimization set value every moment through the dynamic model, thus solving the problem that the pH value control process is large in lag and slow in dynamics, and improving the pH value control quality.

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 invention discloses a process for preparing sulfur from reduction of sulfate/nitrate by iron-carbon and recovering desulfurization/denitration agents. High-concentration SO.sub.2 flue gas produced by calcination of a sulfate and NOx produced by heating decomposition of a nitrate can be directly reduced to elemental sulfur vapor and N.sub.2 through reaction with an iron-carbon material at a high temperature. Then, after dust removal, cooling and fine dust removal, sulfur is recovered by a sulfur recovery device, and metal oxides can replace alkaline mineral resources such as limestone as raw materials of desulfurization (denitration) agents. This process can recycle the desulfurization and denitration agents.

The invention relates to an intelligent multi-pollutant ultra-low emission system and a global optimization method thereof. The intelligent multi-pollutant ultra-low emission system comprises a device layer, a sensing layer, a control layer and an optimization layer from bottom to top. The global optimization method comprises: obtaining an accurate description multiple pollutants in the generation, migration, transformation and removal process in multiple devices by means of accurate modeling of a multi-device multi-pollutant simultaneous removal process of the ultra-low emission system; accurately evaluating multi-pollutant emission reduction costs under different loads, coal qualities, pollutant concentrations and operating parameters through a global operating cost evaluation method of the ultra-low emission system; realizing minute-level planning and optimization of emission reductions of a global pollutant emission reduction device under different emission targets through a multi-pollutant, multi-target and multi-condition global operating optimization method; and guaranteeing reliable emission reduction and margin control of the pollutants through an advanced control method for reliable up-to-standard ultra-low emission of the pollutants.

A carbon dioxide recovery system for collecting carbon dioxide from an exhaust gas generated in a facility including a combustion device includes: a first exhaust gas passage through which the exhaust gas containing carbon dioxide flows; a fuel cell including an anode, a cathode disposed on the first exhaust gas passage so that the exhaust gas from the first exhaust gas passage is supplied to the cathode, and an electrolyte transferring, from the cathode to the anode, a carbonate ion derived from carbon dioxide contained in the exhaust gas from the first exhaust gas passage; and a second exhaust gas passage diverging from the first exhaust gas passage upstream of the cathode so as to bypass the cathode. A part of the exhaust gas is introduced to the second exhaust gas passage.

A device includes a desulfurization system which forms a hydrogen sulfide-containing acid gas; a system for extracting elemental sulfur and a hydrogen sulfide-containing tail gas as exhaust gas; a device for generating electricity and gypsum from the tail gas; and a gas line system for supplying acid gas from the desulfurization system to the system for extracting elemental sulfur and to the device for generating electricity and gypsum, and for supplying tail gas from the system for extracting elemental sulfur to the device for generating electricity and gypsum. The gas line system has a gas distributing apparatus which supplies acid gas solely to the system in a first position, supplies acid gas solely to the device in a second position, and supplies a first part of the acid gas to the system and a second part of the acid gas to the device in a distributing position.

A method of reducing selenium contamination in a waste water stream is described herein. The method includes channeling a flue gas stream through an absorber, contacting the flue gas stream with an aqueous alkaline-based slurry, such that any selenium byproduct in the flue gas stream forms a selenium compound within the aqueous alkaline-based slurry, controlling oxidation of the selenium compound in the aqueous alkaline-based slurry, and adding a precipitation agent to the aqueous alkaline-based slurry to cause the selenium compound within the aqueous alkaline-based slurry to precipitate.

Controlling aerosol production during absorption in ammonia-based desulfurization. The absorption reaction temperature, the oxygen content and water content of the process gas may be controlled, and an absorption circulating liquid containing ammonium sulfite may be used for removing sulfur dioxide in flue gas, so as to control aerosol production during absorption in the ammonia-based desulfurization