Phenol-ammonia coal gasification sewage treatment method

Abstract

The invention relates to a phenol-ammonia coal gasification sewage treatment method, which comprises the four steps of single-tower alkali injection stripping deacidification and deamination, sedimentation filtration, extraction dephenolization and raffinate-phase solvent removal and flashing heat exchange. Phenol-ammonia coal gasification sewage is divided into cold flow and hot flow according to a proportion, the cold flow and the hot flow enter a stripping tower from the top and the middle upper part of the stripping tower respectively, and hot feedstock is the flow, directly heated by steam generated by flashing, of the sewage which is subjected to deamination and acidic gas removal and emitted from the bottom of the stripping tower; acidic gas is emitted from the top of the stripping tower, and a gas mixture is extracted from the side to obtain high-concentration ammonia by three-stage segregation; alkali is injected to a position blow the side to convert an ammonium salt into free ammonia for removal; stripping tower bottoms from which the ammonia and the acidic gas are removed are subjected to counter-current extraction with diisopropyl ether for dephenolization after being flashed and cooled, an extracting agent is recovered through a solvent recovery tower and a water stripping tower, and a crude phenol byproduct is also obtained. According to the method, the treated coal gasification sewage can reach a standard, and meanwhile, the sewage treatment energy consumption is lowered.

Description

technical field [0001] The invention relates to the technical field of coal gasification sewage treatment, in particular to a method for treating phenol ammonia coal gasification sewage. Background technique [0002] my country is a big coal country. With the increasing shortage of petroleum resources, coal chemical industries such as coal-to-oil and coal-to-gas industries are in the ascendant, and serious environmental pollution problems follow. A large amount of highly polluted sewage is produced during the coal gasification process. The sewage comes from the gas washing process. The composition of the sewage is complex. The pollutants mainly include ammonia, carbon dioxide, unit phenols, polyphenols, fatty acids, etc., and also contain a small amount of sulfide. Hydrogen and other pollutants, but also contains a certain amount of inorganic salts and dust. If such sewage is discharged without treatment, it will cause huge damage to the environment. The one-vote veto syst...

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Problems solved by technology

[0004] At present, there are more or less problems in the following aspects in the main processes of coal chemical sewage treatment: 1. The deacidification process is unreasonable, and the acid gases such as ionic carbon dioxide and hydrogen sulfide dissolved in sewage cannot be economically and effectively Converted into free state, the residual amount of acid gas is too high; 2. During deammonization, the separation of ammonia and phenol is not complete, resulting in high content of phenol and acid gas in ammonia products, increasing the load of subsequent ammonia refining; 3. Due to the Contains a certain amount of suspended solids, resulting in serious fouling of heat exchangers and other equipment, poor heat transfer effect of heat exchangers, resulting in high energy consumption for sewage treatment, and the temperature of the extracted sewage after deamination is high, which still needs to be cooled by a subsequent cooler processing, consumes a large amount of circulating cooling water

Therefore, although the coal gasification sewage treatment device can realize the discharge of sewage up to the standard, the energy consumption and operating costs are high, resulting in high production costs, which cannot be afforded by enterprises.

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