Supercritical water oxidation treatment and resource recovery system and method of alkaline paper-making wastewater

Abstract

The invention discloses a supercritical water oxidation treatment and resource recovery system of alkaline paper-making wastewater, which comprises a supercritical water oxidation unit, a black liquidpretreatment unit, an oxidant supply unit, an alkali recovery unit and a white mud utilization unit, wherein a supercritical water oxidation reactor is a multilayer torch firing and multilayer cooling supercritical reactor and is connected with a starting fuel system and a condensate water circulation system; the black liquid pretreatment unit comprises a lignin recovery system, a black liquid conditioning system and a warming and pressurizing system that are sequentially connected; the oxidant supply unit comprises a liquid oxygen booster pump and an air temperature vaporizer; the alkali recovery unit comprises a saline separation tank and a vertical causticizer; a salt discharge port is formed at the bottom of the supercritical water oxidation reactor; and the supercritical water oxidation reactor is sequentially connected with the saline separation tank and the vertical causticizer. The system is high in treatment efficiency, free of pollution discharge, simple to operate and lowerin treatment cost, can simultaneously achieve recycling of resources and energy sources, and saves investment.

Description

technical field [0001] The invention relates to the fields of sewage treatment and resource energy recycling, in particular to a supercritical water oxidation treatment of alkaline papermaking wastewater and a resource recovery system method. Background technique [0002] The paper industry is a traditional large water user. Papermaking wastewater has the characteristics of large water volume, complex components, and refractory degradation. It is one of the important sources of water pollution. According to statistics, the discharge of papermaking and paper products industrial wastewater at or above the county level in my country accounts for 18.6% of the total industrial discharge in the country, and the COD in the discharged wastewater accounts for about 44.0% of the total industrial COD discharge in the country. [0003] Papermaking wastewater mainly includes pulping and cooking waste liquor (also known as black liquor), mid-stage water produced in the washing and bleachi...

AI Technical Summary

Problems solved by technology

Among them, the pollutants contained in the black liquor account for more than 90% of the total pollution discharge of the whole plant, which is characterized by a large amount of wastewater, large chroma, strong alkalinity, and high concentration of organic pollutants. It is difficult to meet the treatment standard. At present, it is generally incinerated after concentration. The solid content of the black liquor is concentrated to more than 45%, and it is burned after thickening in the alkali recovery furnace. The molten material flowing out of the bottom is recovered through the caustic chemical section. The whole process of the method consumes a lot of energy, and it is often necessary to add additional alkali to increase the alkali content to improve the concentration of black liquor, which leads to a further increase in energy consumption. Mud drying; in the combustion process, nitrogen oxides, dust, dioxins and other pollutants will be produced, which will bring harm to the environment

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