Coal chemical industry high-COD and high-salinity concentrated liquor crystallizing and drying method

Abstract

The invention relates to a coal chemical industry high-COD and high-salinity concentrated liquor crystallizing and drying method. The method comprises the following steps that 1, constant-temperature coal chemical industry high-COD and high-salinity concentrated liquor stored in a liquor storage tank is fed into a vacuum rotary drum drying machine through a feeding pump; meanwhile, a heating medium is fed into a center shaft, a bottom material tray and a top clamping sleeve of the vacuum rotary drum drying machine for indirect heat exchange, and solid salt and gas state wastewater are obtained respectively; 2, the gas state wastewater enters a condenser to exchange heat with cooling water, and concentrated wastewater and noncondensable gas are obtained respectively; the concentrated wastewater enters a wastewater collection tank, and the noncondensable gas is pumped out through a vacuum pump to be exhausted; 3, the solid salt is scraped out from the vacuum rotary drum drying machine to fall into a buffer tank, and then is continuously and quantitatively discharged through a two-layer blocking valve. The coal chemical industry high-COD and high-salinity concentrated liquor crystallizing and drying method has the advantages that energy consumption is reduced, cleaning is easy, the grade of needed drying equipment is lowered, and meanwhile the problems of wall sticking and scaling in a conventional evaporator are solved.

Description

technical field [0001] The invention relates to the technical field of coal chemical industry, in particular to a method for crystallization and drying of high-COD and high-salt concentrated liquid in coal chemical industry. Background technique [0002] Globally, coal is more plentiful and relatively cheap than oil and natural gas, and oil shortages are growing. Some coal-rich countries such as the United States, Australia, India, Germany, etc., are stepping up research or development of coal chemical projects. In recent years, my country has also researched and developed new coal chemical technology, established a number of coal chemical demonstration projects, and established the world's largest coal-to-oil project. However, for coal chemical projects in areas rich in coal resources but short of water resources, in the case of large water consumption and sewage discharge, there is an urgent need for feasible coal chemical wastewater collection and reuse treatment technol...

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Problems solved by technology

[0003] At present, the coal chemical process is in a stage of rapid development, but the treatment process of coal chemical wastewater is relatively backward, especially the high COD and high salt concentrated liquid produced by membrane separation or thermal concentration process for coal chemical wastewater with high COD and high salt

The salt content of such high-COD and high-salt concentrates has usually reached saturation, and the composition is complex, except for Cl - , SO 4 2- 、Na + In addition, it also contains calcium and magnesium ions. During the evaporation process, some components in this kind of concentrated liquid are difficult to crystallize (compared to the main components sodium chloride and sodium sulfate), and it will also affect the precipitation of the main salt, especially It is a resource problem that affects the crystallized salt and affects the quality of the salt; in addition, high COD is easy to enrich during the evaporation process, and after enrichment, it also affects the evaporation process, such as making the dope easy to foam, increasing the viscosity, and increasing the heat transfer coefficient. In view of the above problems of high COD, high salt concentrated liquid evaporation and crystallization and the country's increasing emphasis on environmental protection, it is imminent for enterprises to seek an effective and simple way to deal with high COD and high salt concentrated liquid in coal chemical industry

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