Hot wastewater concentration system directly draining hot-air natural circulation water and method

Abstract

The invention discloses a hot wastewater concentration system directly draining hot-air natural circulation water and a method. According to the system and the method, air is heated by a heat exchanger from an air inlet unit, hot air is obtained, the hot air is taken as carrier gas and enters from an air inlet of a distilling concentration tower, the hot air forms convection with hot wastewater which is sprayed from the upper end of the distilling concentration tower, preheated by a preheater and heated by the heat exchanger in the distilling concentration tower, part of water in the wastewater is taken away by air, and wet saturated air and a wastewater concentrated solution are obtained respectively. After the wet saturated air is subjected to phase change heat exchange by the preheater,water steam is condensed to form condensed water and dehumidified air, the dehumidified air enters the air inlet unit for natural circulation, and the condensed water and the wastewater concentratedsolution in a conical concentrated solution collecting bucket are drained naturally.

Description

technical field [0001] The invention relates to the field of waste water treatment, and relates to the concentration and weight reduction of waste water, in particular to a hot waste water concentration system with direct discharge of hot air natural circulation water and a waste water air distillation concentration method based on the system. The waste water can be desulfurization waste water. Background technique [0002] The desulfurization wastewater zero discharge system generally includes three parts: a pretreatment unit, a concentration reduction unit, and a terminal solidification unit. [0003] At present, the concentration and weight reduction technologies used at home and abroad mainly include thermal concentration (such as: MVC / MED evaporation concentration), membrane concentration (such as: RO high-pressure reverse osmosis, FO forward osmosis concentration). [0004] MVC / MED thermal concentration technology: it can concentrate the desulfurization wastewater pret...

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Problems solved by technology

[0004] MVC / MED thermal concentration technology: it can concentrate the desulfurization wastewater pretreatment water to TDS≤200,000ppm. The main problems are as follows: 1) Due to the strong corrosiveness of high-salinity wastewater, all equipment components in contact with wastewater The use of expensive metal materials results in higher equipment costs; 2) Since the heat transfer surface of steam and wastewater is extremely important, if scaling is formed on the heat transfer surface, the system performance will be greatly reduced. 3) When the salinity of wastewater is high, the corresponding boiling point rise is also high (for example, the boiling point of sodium chloride solution rises to 13°C under saturated concentration conditions), and the energy efficiency of evaporation and concentration technology is not high at this time. , resulting in increased operating costs

Therefore, there are common problems such as high investment, operation and maintenance costs, large floor area, and serious scaling and corrosion of equipment.

[0005] Membrane concentration technology: FO forward osmosis and RO high-pressure reverse osmosis concentration technology can concentrate desulfurization wastewater pretreatment water to TDS ≤ 180,000 ppm and TDS ≤ 100,000 ppm respectively, and the investment, operation and maintenance costs and floor area are slightly lower than MVC / MED thermal concentration technology, 1) In order to prevent fouling of membrane elements, it has high requirements for wastewater pretreatment, which increases the investment and operation and maintenance costs of pretreatment; 2) The membrane elements continue to deteriorate during operation, requiring regular Cleaning and replacement increase the cost of operation and maintenance; 3) Due to the limitation of membrane technology, the concentration ratio of wastewater is low, and the discharge of concentrated water is higher than that of MVC / MED thermal concentration technology, which increases the cost of terminal treatment (such as: evaporation crystallization, etc.) Investment and operation and maintenance costs; 4) Common problems such as difficult cleaning of membrane systems, short cleaning cycle and service life, and poor load impact resistance

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