Method for recovering sewage of artificial board production system

Abstract

The invention relates to a method for recovering sewage of an artificial board production system, belonging to the technical field of energy saving, environmental friendliness and comprehensive utilization for artificial board production. The technical scheme of the invention is as follows: the characteristics that the existing artificial board production system has a water washing process and needs a lot of air to dry wood fibers are utilized, a vacuum concentrating and heating device is additionally arranged, the sewage produced by the artificial board production system is evaporated under the conditions of low temperature and low pressure and is changed into water vapor, the air of the artificial board production system is ingeniously adopted as a cooling medium, the water vapor is cooled as high-added-value condensed water for recycling, and meanwhile, the heat of the water vapor is transferred to the air so as to increase the temperature of the air, thus the energy consumption of a dry air heater is lowered, the heat utilization ratio is high, the operating cost is low, the existing large sewage treatment device can be completely replaced, and the zero discharge of sewage is realized. The method is simple, feasible, energy-saving and environmental-friendly; compared with the background art, the investment is decreased by over 80%, and the operating cost is decreased by over 50%.

Description

technical field [0001] The invention relates to a method for recycling and treating sewage in a wood-based panel production system, and belongs to the technical fields of energy saving, environmental protection and comprehensive utilization of wood-based panel production. Background technique [0002] The sewage generated in the production process of wood-based panels is mainly wood chips and other raw materials washing and drainage, cork screw extrusion water, wood chip cooking wastewater, ground washing water, etc.; the sewage contains a large amount of suspended matter such as mud, bark, wood chips, fibers, etc. , wood powder, etc., and also contains some plant fiber extracts such as cellulose, lignin, resinous compounds, etc.; resinous compounds include resinous acids, long-chain fatty acids, tannin compounds, etc. This kind of wastewater has the characteristics of high concentration of organic matter and suspended matter, and is a kind of high-concentration organic wast...

AI Technical Summary

Problems solved by technology

The traditional treatment process for this kind of sewage generally adopts pretreatment, anaerobic biochemical treatment, aerobic biochemical treatment and sludge treatment. During the treatment process, more coagulants, flocculants, acids, alkalis and other Auxiliaries, etc.; the main problems are large investment, high treatment cost, complicated operation, unstable external drainage indicators, and easy pollution to the environment; at the same time, organic compounds such as cellulose, lignin, and resins in wastewater have undergone flocculation and precipitation Part of it enters the sludge, and part of it is decomposed into carbon dioxide after biochemical treatment, and the treated water COD, BOD and other indicators meet the standards, but the concentration of salt substances increases significantly and cannot be fully recycled, resulting in water resources and cellulose, wood, etc. waste of organic compound resources such as pigments and resins

[0003] In response to the above problems, someone proposed a zero-discharge process for wood chip washing wastewater, for example: as described in Chinese Patent No. 201110328244.9, the main problem of this process is: when the moisture content of the raw material is low, generally the relative moisture content is ≤50% (weight percentage) When the cork screw squeezes out less water, the wood chip washing and circulating water system can consume this part of the water, which can realize zero discharge of sewage; ), the amount of water extruded by the cork screw is large, and the wood chip washing circulating water system cannot consume this part of the water, causing the circulating water system to swell and be forced to drain, causing environmental pollution

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