Mechanical vapor recompression system of concentrated organic waste water and method

Abstract

The invention discloses a mechanical vapor recompression system of concentrated organic waste water and an application method of the mechanical vapor recompression system, and relates to the technical field of energy conservation and emission reduction. A second-stage evaporating unit is added outside a heat exchange pipe of an existing MVR evaporator, secondary heat exchange is conducted on the evaporator through an outer heating source, and therefore the ethanol concentration of a concentrated solution concentrated through MVR is further improved, the energy utilization efficiency is improved, and the waste water volume and energy consumption in the reconcentration process are lowered. Due to an added rectifying tower and an added condensation device, the utilization efficiency of the outer heating source is fully improved, the ethanol concentration in vapor can be reduced, and convenience is provided for making the waste water meet the emission requirements. The procedures are simple, operation is convenient, and a cooling water system can be omitted.

Description

technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a system and method for concentrating low-concentration organic waste water by mechanical vapor recompression. Background technique [0002] Organic wastewater contains a large amount of carbohydrates, fats, proteins, cellulose and other organic matter. If it is directly discharged, it will reduce the dissolved oxygen in the water and affect the growth of fish and other aquatic organisms. Water-soluble organic compounds, such as low-molecular-weight organic alcohols, especially glycols, are often used as good freezing point depressants for deicing, anti-icing, and anti-freezing of vehicles and equipment, which may produce a large amount of low-concentration organic compounds in a short time. Alcohol-containing wastewater, the average COD of such wastewater exceeds 20,000 mg / L. Organic wastewater containing low concentrations of organic matter will seriously harm the ...

AI Technical Summary

Problems solved by technology

Although the device uses a power supply to achieve the concentration of wastewater, and does not need to use Freon and other heat transfer media, which reduces the cost, it is mainly used to treat salty organic wastewater, and it is not effective for organic wastewater that is easily carried out with steam.

[0010] Although the mechanical vapor recompression system has the advantages of reducing energy consumption and reducing the amount of fresh steam, its operating cost and energy consumption are closely related to the boiling point of the material, especially when concentrating low-concentration alcohol-containing wastewater, due to the high boiling point of alcohol-containing wastewater , the temperature difference loss is large, which will lead to a decrease in the evaporation concentration ratio of the MVR system, which is not conducive to increasing the alcohol concentration in the system concentrate

At the same time, since the dihydric alcohol in the wastewater is easily taken out by water vapor during the evaporation of alcohol-containing chemical wastewater, the condensed water after evaporation contains more dihydric alcohol, so it cannot meet the discharge requirements

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