An absorption column is equipped with: a CO.sub.2 absorption section absorbing CO.sub.2 from CO.sub.2-containing exhaust gas using a lean solution; a main rinse section recovering an entrained CO.sub.2 absorbent using rinse water; a rinse water circulation line circulating a rinse water containing the CO.sub.2 absorbent recovered in a liquid storage section of the main rinse section; a pre-rinse section provided between the CO.sub.2 absorption section and the main rinse section; a rinse section extraction liquid supply line extracting a portion of the rinse water containing the CO.sub.2 absorbent from the rinse water circulation line, and introducing the same into a reflux section of an absorption liquid regeneration tower; and a refluxed water supply line extracting a portion of refluxed water, introducing the same as pre-rinse water for the pre-rinse section, and connected on the pre-rinse section side.

Elemental sulfur carrying capacity of a hydrocarbonaceous solvent is improved by first loading the solvent with sulfur and subsequent hydrotreatment under conditions that convert at least some of the elemental sulfur in the sulfur loaded solvent to hydrogen sulfide while preserving at least 95% of the monoaromatic and polyaromatic components in the solvent.

A process and system for treating a hydroprocessing unit effluent gas stream for recycling includes introducing the effluent gas stream into a hydrogen purification zone and recovering a hydrogen-rich gas stream and a liquid stream containing a mixture that includes C1 to C4 hydrocarbons and H.sub.2S which is then mixed with an oxidant and fed to an oxidation unit containing catalyst for conversion of the H.sub.2S to elemental sulfur vapors that is separated for recovery of the elemental sulfur, and recovering a sweetened mixture that includes C1 to C4 hydrocarbons. Alternatively, the hydroprocessing unit effluent gas stream containing H.sub.2S is cooled, contacted with a solvent to absorb the C1 to C4 hydrocarbons and H.sub.2S, with the hydrogen-rich stream being recovered for recycling to the hydroprocessing unit, and the rich liquid solvent being flashed to produce a lean solvent stream for recycling to the adsorption zone and a mixed gas stream that includes the C1 to C4 hydrocarbons and H.sub.2S that is passed to an oxidation zone and is reacted with an oxidant in the presence of a catalyst to complete the process as described above for the recovery of elemental sulfur and a mixture that includes the sweetened C1 to C4 hydrocarbons.

The present disclosure is directed to methods for treating an organic material, including the steps of transporting the organic material into a first vessel; heating the organic material in the first vessel and applying a negative pressure to the organic material in the first vessel to a boiling point of the organic material, wherein the heat and negative pressure separates a portion of an ammonia from the organic material; removing the portion of the ammonia from the first vessel; transporting the removed portion of the ammonia from the first vessel to an acid solution in a second vessel; and separating a portion of the ammonia from the acid solution.

A system for purifying mother liquid steam of polytetrafluoroethylene dispersion liquid comprises a concentration kettle (1), a defoaming pot (2), a gas-liquid separator (3) and a falling film absorption tower (4). A steam exit of the concentration kettle (1) is connected to an entrance of the defoaming pot (2). An exit of the defoaming pot (2) is connected to a feeding port of the gas-liquid separator (3). A gas exit of the gas-liquid separator (3) is connected to the falling film absorption tower (4). A liquid exit of the gas-liquid separator (3) is connected to the concentration kettle (1). A method for purifying mother liquid steam of polytetrafluoroethylene dispersion liquid by using the system is further provided.

A carbon dioxide capture system includes: a washing unit which uses cleaning water to clean absorption unit exhaust gas or stripping unit exhaust gas; and a gas-liquid separation device which allows condensed water generated by cooling washing unit exhaust gas to be separated from the washing unit exhaust gas. The condensed water is mixed into the cleaning water by a condensed water line. If the amount of the cleaning water becomes more than a predetermined amount, the cleaning water is mixed into an absorbing liquid by a cleaning water line. A controller controls a condensed water valve.

The present invention provides a carbon dioxide recovery apparatus capable of recovering heat energy of carbon-dioxide-containing gas which includes an absorbing tower to generate and discharge a rich liquid absorbing carbon dioxide as carbon-dioxide-containing gas is introduced and contacted to an absorbing liquid to absorb carbon dioxide, carbon dioxide release devices to discharge semi-lean liquids which have steam containing a part of carbon dioxide released by heating the rich liquid discharged from the absorbing tower, and a regeneration tower to generate a lean liquid which has steam containing remaining carbon dioxide released and separated by heating the semi-lean liquids discharged from the carbon dioxide release devices and to return the lean liquid to the absorbing tower.

The present invention relates to an improved method for removing contaminants from a gaseous stream substantially comprising carbon dioxide. More specifically, the method comprises the step of subjecting the gaseous stream to an absorption step in which the absorbent is liquid carbon dioxide wherein the waste of carbon dioxide is minimized by utilizing a compressing means for generating a pressure difference between two streams in a reboiler.

The object is to prevent deterioration and loss of dicyanobenzene in producing dicyanobenzene by ammoxidation of xylene to thereby achieve industrial and economical advantage in producing of dicyanobenzene. The method for producing dicyanobenzene of the present invention includes: contacting a xylene-ammoxidation reaction gas containing dicyanobenzene in ammoxidation of xylene with an organic solvent so as to obtain a dicyanobenzene-absorbing solution; contacting the dicyanobenzene-absorbing solution with a basic aqueous solution containing a salt such as ammonium carbonate so as to extract a water-soluble salt formed by neutralization reaction between carboxylic acid in the dicyanobenzene-absorbing solution and a base in the basic aqueous solution into an aqueous phase; separating the mixture of the dicyanobenzene-absorbing solution and the basic aqueous solution into an organic phase and an aqueous phase; decomposing the salt such as ammonium carbonate contained in the organic phase for separation of the salt from the organic phase; and distilling the organic phase to separate low boiling point compounds contained in the organic phase from the organic phase so as to obtain dicyanobenzene.

A process for purification of waste from zootechnical sources or from small agri-food companies is provided. A plant for carrying out the wastewater treatment process is also provided.