A high-temperature wet oxidation method for treating waste caustic soda

Abstract

The invention discloses a method for treating waste lye by high-temperature wet oxidation. At 220°C to 260°C and under the pressure of keeping the waste lye in liquid phase, the waste lye is contacted with air exceeding the theoretical oxygen demand, and the waste lye is used The oxygen in the air oxidizes the inorganic sulfide and organic matter in the waste caustic so that the sulfur in it is converted into sulfate, and the organic matter is oxidized and decomposed into water and carbon dioxide; the reacted material discharged from the wet liquid phase oxidation reactor enters the high-pressure gas-liquid separator , The oxidized spent lye after gas-liquid separation and the waste lye feed are exchanged for heat, and the oxidized spent lye after heat exchange and the gas phase separated from gas and liquid enter the cooling and washing tower. Compared with the prior art, the method of the present invention has low energy consumption, the removal rate of S2- can reach 100%, the removal rate of COD can reach 75%-85%, and the waste lye after treatment can be directly discharged into the sewage treatment system, effectively alleviating the The pressure brought by the high concentration of wastewater in sewage treatment plants.

Description

technical field [0001] The invention relates to a method for treating waste lye by a high-temperature, high-pressure wet oxidation method, in particular to a method for treating waste lye discharged from an alkali refining process in the petroleum refining industry and the ethylene industry. Background technique [0002] In the process of petroleum refining and processing, in order to ensure the quality of oil products and control the SO 2 Alkaline refining is usually carried out for oil products with higher sulfur content. The waste lye discharged during this process contains high concentrations of sodium sulfide, sulfur-containing organic compounds, and organic compounds such as acidic phenols and organic acids. In the ethylene industry, ethylene cracking waste lye also contains a large amount of sulfide and hydrocarbons. The emissions of COD (chemical oxygen demand, chromium method, hereinafter the same), sulfides, phenols, and naphthenic acids in the above-mentioned sp...

AI Technical Summary

Problems solved by technology

[0004] Practice has proved that the above process has the following disadvantages: (1) The high temperature and high pressure wet oxidation process is mainly based on the introduction of foreign complete sets of technology, usually the processing capacity is not high, and the one-time investment and operation costs are high

(2) Although the moderate wet oxidation + SBR process can remove sulfides up to 100% under moderate conditions, the removal rate of COD is only 20% to 40%, which will inevitably increase the subsequent oily sewage System processing load and potential for shock

[0005] With the continuous enlargement of the scale of oil refineries and ethylene plants, the amount of sulfide-containing wastewater produced is also increasing. However, the wastewater treatment capacity of existing wet oxidation reactors is limited. Due to structural limitations, simple expansion Reactor size does not effectively increase throughput

For example, the wet air oxidation reactor disclosed in CN00220715.X for the treatment of waste water containing sulfides and the like adopts a simple sleeve structure, but its disadvantage is that the amount of waste water treatment cannot be effectively increased. After simple size enlargement, the performance of the reactor will decrease It is greatly reduced and cannot meet the needs of the reaction, especially for waste lye with high COD.

Images