Systems and methods for producing chlorine dioxide in a single vessel process include a simplified control of sodium sulfate concentration, particularly for small to medium scale chlorine dioxide generators. The benefits of the described systems and methods include high chlorate efficiency, compact design and low sulfuric acid use. In some embodiments, the described systems and methods produce chlorine dioxide and separate the chlorine dioxide for use in the treatment of drinking water. The separated chlorine dioxide for use in the treatment of drinking water has no chlorate of chlorite or levels of chlorate or chlorite that are well below allowed limits. Novel compositions from which to produce chlorine dioxide include mixtures of hydrogen peroxide and a miner al acid and mixtures of an alkali metal chlorate, alkali metal salt and hydrogen peroxide are also described.

A process of separating phosgene and hydrogen chloride, comprises: conveying a mixed stream containing hydrogen chloride and phosgene into a distillation column; withdrawing from the distillation column a bottom stream containing phosgene; withdrawing a top stream containing hydrogen chloride; compressing at least a portion of the top stream and at least partially condensing the compressed top stream to form a liquid stream, decompressing at least a portion of the liquid stream to form a cooled liquid stream and a cooled gas stream; and recycling the cooled liquid stream to the top of the distillation column as a reflux; the process additionally comprising temporarily introducing an absorbing solvent into the distillation column, in particular during starting-up and/or shutting-down of the process. The process allows for safe operation even when hydrogen chloride production only gradually begins or decreases, without the necessity of storing hydrogen chloride.

A system includes an ion separation unit that may receive dilute hydrochloric acid and may generate a concentrated hydrochloric acid and a chamber fluidly coupled to the ion separation unit. The chamber may receive the concentrated hydrochloric acid and may separate the concentrated hydrochloric acid into a liquid concentrated hydrochloric acid and a vapor containing vaporized hydrochloric acid. The system also includes a scrubber fluidly coupled to the chamber. The scrubber may receive the vapor from the chamber, and the scrubber is may remove at least a portion of the vaporized hydrochloric acid from the vapor via a purified condensate to generate a purified vapor and the dilute hydrochloric acid. The system also includes a condenser fluidly coupled to the scrubber The condenser may receive the purified vapor from the scrubber to condense the purified vapor into the purified condensate, and to output the purified condensate to the scrubber.

A hydrogen gas recovery system according to the present ingestion is configured by a condensation and separation apparatus (A) that condenses and separates chlorosilanes from a hydrogen-containing reaction exhaust gas exhausted from a polycrystalline silicon production step, a compression apparatus (B) that compresses the hydrogen-containing reaction exhaust gas, an absorption apparatus (C) that absorbs and separates hydrogen chloride by contacting the hydrogen-containing reaction exhaust gas with an absorption liquid, a first adsorption apparatus (D) comprising an adsorption column filled with activated carbon for adsorbing and removing methane, hydrogen chloride, and part of the chlorosilanes each contained in the hydrogen-containing reaction exhaust gas, a second adsorption apparatus (E) comprising an adsorption column filled with synthetic zeolite that adsorbs and removes methane contained in the hydrogen-containing reaction exhaust gas, and a gas line (F) that recovers a purified hydrogen gas having a reduced concentration of methane.

A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler. Some embodiments of a biogas cleaning method can also include precooling the biogas waste stream, adsorbing siloxanes from the biogas waste stream and adsorbing hydrogen chloride from the biogas stream.

A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler. Some embodiments of a biogas cleaning method can also include precooling the biogas waste stream, adsorbing siloxanes from the biogas waste stream and adsorbing hydrogen chloride from the biogas stream.

Provided is a method for producing a hydrogen chloride that is capable of efficiently producing a hydrogen chloride with a simple facility. The hydrogen chloride is produced by a method including causing an inert gas to be in gas-liquid contact with a hydrochloric acid in which a concentration is 20 mass % to 50 mass %, distilling the hydrochloric acid with which the inert gas is in gas-liquid contact in the gas-liquid contact and separating a hydrogen chloride from the hydrochloric acid to obtain a crude hydrogen chloride, dehydrating the crude hydrogen chloride obtained in the separating, and compressing and liquefying the dehydrated crude hydrogen chloride obtained in the dehydrating, and purifying the liquid crude hydrogen chloride by distillation.

Provided is a method for producing a hydrogen chloride that is capable of efficiently producing a hydrogen chloride with a simple facility. The hydrogen chloride is produced by a method including causing an inert gas to be in gas-liquid contact with a hydrochloric acid in which a concentration is 20 mass % to 50 mass %, distilling the hydrochloric acid with which the inert gas is in gas-liquid contact in the gas-liquid contact and separating a hydrogen chloride from the hydrochloric acid to obtain a crude hydrogen chloride, dehydrating the crude hydrogen chloride obtained in the separating, and compressing and liquefying the dehydrated crude hydrogen chloride obtained in the dehydrating, and purifying the liquid crude hydrogen chloride by distillation.

Provided is a calcium carbonate generation method and system in which calcium carbonate having a high purity can be generated using a calcium-containing waste. Provided is a calcium carbonate generation method of generating calcium carbonate from a calcium-containing waste, the calcium carbonate generation method including: a calcium dissolution step of adding aqueous hydrochloric acid to a calcium-containing waste and dissolving calcium to generate an aqueous solution containing a calcium ion; a separation step of adjusting a hydrogen ion concentration index of the aqueous solution containing a calcium ion and separating a component containing at least one selected from the group consisting of Si, Al, Mg, and heavy metal from the aqueous solution; and a calcium carbonate collection step of generating calcium carbonate using an aqueous solution obtained in the separation step and an aqueous solution containing potassium carbonate and/or sodium carbonate.

Provided is a calcium carbonate generation method and system in which calcium carbonate having a high purity can be generated using a calcium-containing waste. Provided is a calcium carbonate generation method of generating calcium carbonate from a calcium-containing waste, the calcium carbonate generation method including: a calcium dissolution step of adding aqueous hydrochloric acid to a calcium-containing waste and dissolving calcium to generate an aqueous solution containing a calcium ion; a separation step of adjusting a hydrogen ion concentration index of the aqueous solution containing a calcium ion and separating a component containing at least one selected from the group consisting of Si, Al, Mg, and heavy metal from the aqueous solution; and a calcium carbonate collection step of generating calcium carbonate using an aqueous solution obtained in the separation step and an aqueous solution containing potassium carbonate and/or sodium carbonate.