Dilute sulfuric acid and MVR coupled freeze concentration system and method thereof

Abstract

A dilute sulfuric acid and MVR (mechanical vapor recompression) coupled freeze concentration system and a method thereof belong to the fields of energy saving and environmental protection. The systemincludes a raw material tank, a freezing tank, a water washing tank, an ice thawing tank, a product tank, a condensate water tank, a preheater, a throttle valve, adsorbing devices, a motor, a vapor compressor and the like. The method is characterized in that a dilute sulfuric acid solution is pressurized by a circulating water pump, enters the preheater, is preheated, and exchanges heat with a low-temperature liquid low-boiling point working medium in the freezing tank, the-low boiling point working medium absorbs the heat and becomes a gas, the gas enters the compressor and is compressed, thesulfuric acid solution releases heat to make water precipitated in an ice cube form, obtained ice cubes are flushed by the water washing tank, enter the ice thawing tank, and are heated and thawed bythe high-temperature high-pressure gaseous working medium which is compressed by the compressor in order to form water, and the water is collected into the condensate water tank in order to separatewater in the dilute sulfuric acid solution and realize the low-temperature concentration of the dilute sulfuric acid solution. The system and method have the characteristics of low energy consumptionand low corrosiveness, and are suitable for the efficient recycling of dilute sulfuric acids in industries of chemical engineering, foods, medicines, hardware, electroplating and steel.

Description

technical field [0001] The invention relates to a dilute sulfuric acid MVR coupled freeze concentration system and method, belonging to the field of energy saving and environmental protection. Background technique [0002] With the advancement of science and technology and the rapid development of industry, rational use of energy and protection of the ecological environment have become an urgent need for many industries. Sulfuric acid is one of the most widely used chemical products in my country. In many industrial production processes, the utilization rate of sulfuric acid is low and the discharge of waste acid is large, which not only causes waste of resources, but also aggravates environmental pollution. Change. [0003] At present, sulfuric acid is mainly recovered and reused through extraction, dialysis, heating and concentration. The extraction method uses an extractant to separate sulfuric acid from sulfuric acid waste liquid, and can obtain sulfuric acid with a conc...

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Problems solved by technology

Sulfuric acid is the most widely used chemical product in my country. In many industrial production processes, the utilization rate of sulfuric acid is low and the discharge of waste acid is large, which not only causes waste of resources, but also aggravates environmental pollution. Therefore, the recycling of sulfuric acid is urgently needed Change

[0003] At present, sulfuric acid is mainly recovered and reused by methods such as extraction, dialysis, and heating and concentration. The extraction method uses an extractant to separate sulfuric acid from sulfuric acid waste liquid, and can obtain sulfuric acid with a concentration of 60%. However, the process is complicated and energy consumption Larger; dialysis method is aimed at the separation of acid and salt in waste liquid, and cannot obtain higher concentration of sulfuric acid; heating concentration can be divided into direct heating and indirect heating concentration, direct heating includes drum concentration, immersion combustion method, spray evaporation concentration method and Venturi concentration method, etc., indirect heating methods include pot concentration method, vacuum concentration method, etc.

[0004] Graphite multi-effect evaporator is a widely used concentration equipment with good heat transfer performance and high concentration efficiency, but its cost is high; MVR technology is an energy-saving and environmental protection technology advocated by the state. It passes the secondary vapor evaporated in the material liquid through The compressor is compressed into high-temperature and high-pressure steam, which is used as a heat source again to heat the feed liquid, making full use of the potential of the secondary steam, and can realize the concentration of dilute sulfuric acid. They all belong to the heating and evaporation process, with strong production capacity and high concentration. Sulfuric acid, but due to the need for high temperature and vacuum conditions, the energy consumption is large, and sulfuric acid is highly corrosive in a high temperature environment, and it is easy to damage the equipment

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