MVR-heat pump coupled multi-effect evaporation water treatment system and working method thereof

Abstract

The invention discloses an MVR-heat pump coupled multi-effect evaporation water treatment system and a working method thereof. The system comprises an MVR multi-effect evaporation cycle and a compression heat pump cycle. The method comprises the steps that a part of secondary steam in a first-effect evaporator serves as a heat source of a next-effect evaporator, a part of the secondary steam is mixed with last-effect secondary steam obtained after first-stage compression, the mixture enters a second steam compressor to be compressed and then enters the first-effect evaporator, a part of heat of first-effect condensate water is recycled through an evaporator of a compressor heat pump, and another air source evaporator absorbs heat from ambient air and is used for evaporating a part of the condensate water in the first-effect evaporator to generate steam, thereby maintaining stable operation of the system. The method for evaporating a part of the condensate water through the compression type heat pump completely meets the requirement for extra fresh steam supply during operation of an MVR multi-effect evaporation system; and by means of the method for directly compressing a part of high-pressure secondary steam, the purposes of reducing compression energy consumption, reducing the size of a compressor and reducing initial investment can be achieved.

Description

technical field [0001] The invention belongs to the technical field of industrial water treatment and heat recovery, and relates to a water treatment system coupled with an MVR multi-effect evaporation and a compression heat pump and a working method thereof. Background technique [0002] In many industrial fields such as chemical industry, petroleum, pharmaceuticals, etc., it is an indispensable method to use evaporation technology to treat industrial wastewater. High unit operations. The energy consumption and the waste heat of the evaporation system in traditional industries are still relatively serious. The traditional single-effect distillation concentration method, the secondary steam cannot be reused, and most of them only recycle and recover about 30% of waste heat and waste heat. The discharge of secondary steam not only wastes the latent heat of steam, but also some materials will flow out of the evaporation system together with the secondary steam, which will cau...

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Problems solved by technology

[0002] In many industrial fields such as chemical industry, petroleum, pharmaceuticals, etc., it is an indispensable method to use evaporation technology to treat industrial wastewater. high unit operations

The energy consumption and the waste heat of the evaporation system in traditional industries are still relatively serious. The traditional single-effect distillation concentration method, the secondary steam cannot be reused, and most of them only recycle and recover about 30% of waste heat and waste heat. The discharge of secondary steam not only wastes the latent heat of steam, but also some materials will flow out of the evaporation system together with the secondary steam, which will cause certain pollution to the environment

[0003] At present, the most commonly used method for recovery of waste heat from low-temperature secondary steam is mechanical steam recompression. However, the heat energy provided by the high-temperature and high-pressure steam produced by the traditional MVR multi-effect evaporation system is not enough to meet the The heat energy required for one-effect evaporation often needs to be supplemented by other forms of heat source steam, so a method with good stability and low energy consumption is urgently needed to provide heat source steam, and it is best to solve the problem of generating supplementary steam more reasonably. source of water

[0004] In addition, with the increase of the number of evaporators in the multi-effect MVR system, the steam pressure of the terminal evaporator is low. When using MVR to recover the steam waste heat, the compressor pressure ratio is large and the energy consumption is large. The volumetric flow rate of the machine will also be particularly large, resulting in large compressor size and initial investment, which severely limits the application and promotion of MVR multi-effect evaporation technology, so it is necessary to effectively solve the problems of high energy consumption and large volumetric flow rate of the compressor

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