A paper mill wastewater zero discharge and resource recycling method based on waste heat drive

Abstract

The invention relates to a paper mill sewage zero-emission and resource recovery method based on waste heat drive, and belongs to the technical field of papermaking processes and energy-saving and environmental protection. The whole system comprises four process modules of a thermal method sewage treatment and resource module, a demineralization water module, a boiler and heat recovery module anda papermaking process waste heat recovery module. According to the present invention, various waste heats in the plant are used as the driving heat source for the sewage evaporation and crystallization device, evaporation concentration reduction, thermal method evaporation and high-purity salt separation are performed on the whole plant wastewater, the high-grade steam for heating deaerators, process water, heating backwater and the like or the flue gas high-temperature section sensible heat and the like are used for waste heat evaporation crystallization, purification and mother liquor drying, and the secondary steam on the sewage side is used for preheating the heated object; and the papermaking drying process high-temperature and high-humidity waste heat, the raw material cooking and grinding pulping process normal-pressure secondary waste steam and the flue gas waste heat are used for negative pressure waste heat evaporation and concentration , the recovered clear water can be usedfor demineralization water supplementing, and the solid matter can be used as industrial raw material, building materials and boiler blending fuels.

Description

technical field [0001] The invention relates to a waste heat-driven zero discharge and resource recovery method for paper mill sewage, which belongs to the technical field of papermaking technology and energy saving and environmental protection. Background technique [0002] Paper mills belong to the traditional high-energy-consumption, high-pollution, and high-emission industries. Currently, one of the biggest environmental problems and industry bottlenecks plaguing this industry is the massive discharge of sewage, especially high-salt wastewater, which seriously pollutes the environment, especially for underground soil and groundwater. The pollution of resources etc. is becoming more and more serious, and it is extremely difficult to recover. Although there are social voices, policy expectations and enterprise attempts to universally implement zero discharge of sewage and water resource reuse, the current conventional treatment methods, including the technical route of pre...

AI Technical Summary

Problems solved by technology

[0002] Paper mills belong to the traditional high-energy-consumption, high-pollution, and high-emission industries. Currently, one of the biggest environmental problems and industry bottlenecks plaguing this industry is the massive discharge of sewage, especially high-salt wastewater, which seriously pollutes the environment, especially for underground soil and groundwater. The pollution of resources etc. is getting worse and it is extremely difficult to recover

Although there are social voices, policy expectations and enterprise attempts to universally implement zero discharge of sewage and water resource reuse, the current conventional treatment methods, including the technical route of pretreatment + membrane treatment + MVR evaporation or multi-effect evaporation, exist. The biggest problem is: the initial investment is huge (at present, the investment demand for a ton of sewage, which is usually equivalent to 1t / h, is about 300,000 to 1 million yuan), and the operating energy consumption and operation and maintenance costs are too high (currently, it is usually equivalent to 30 to 90 yuan per ton of sewage treatment. At the same time, a large amount of waste salt and other solids discharged during the process of achieving zero sewage discharge are usually treated as hazardous waste, which must be disposed of in accordance with legal regulations, including disposal fees, environmental protection taxes The total comprehensive disposal cost, including the cost, is about 4,000-8,000 yuan / t

When adopting the above-mentioned waste heat utilization method for zero discharge of sewage, the incremental energy consumption is almost negligible except for the power consumption of the relevant water pumps, so the energy cost of the zero discharge of sewage is mainly the electricity cost for the operation of the water pumps in the process, etc.

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