Packaged treatment method capable of reducing hardness of grey water and reducing volume of grey water discharged out by system

Abstract

The invention discloses a packaged treatment method capable of reducing hardness of grey water and reducing volume of the grey water discharged out by a system. The method comprises the following steps: cooling the grey water discharged out by a grew water tank of a coal gasification system by virtue of a heat exchanger until water temperature is not higher than 35 DEG C; enabling the cooled grey water to enter an EDR device to be treated, so as to obtain softened water and concentrated water, wherein the softened water enters the grey water to be recycled, and the concentrated water enters a black water settling tank of the coal gasification system; according to the hardness and alkalinity of black water, continuously adding a flocculating agent into the black water in the black water settling tank, and also continuously or discontinuously adding a right amount of hardness reducing agent, so that the produced precipitation particles which are calcium salt and magnesium salt mainly are flocculated and settled to the bottom of the black water settling tank along with suspended solids; and enabling the grey water overflowing at the upper part of the black water settling tank to enter the grey water tank, carrying out filter pressing on mud produced at the bottom of the black water settling tank through flocculation settling, and discharging out the obtained filter cake. The method has the advantages that the hardness of circulating grey water of the coal gasification system is effectively reduced, scale formation is delayed, and the failure rate of the system equipment is reduced; meanwhile, the water circulation utilization rate of the coal gasification system is greatly improved.

Description

Technical field: [0001] The invention belongs to the water treatment technology of a coal gasification slag water system, and in particular relates to a complete treatment method for reducing the hardness of ash water in a coal gasification system and significantly reducing the amount of ash water discharged from the coal gasification system. Background technique [0002] Coal gasification technology is a key common technology in the field of clean coal technology; it has the characteristics of high efficiency and ultra-clean, and is the mainstream of coal technology development in the world today. Among coal gasification technologies, entrained bed coal gasification technology is more suitable for large-scale industrial production. [0003] In the past ten years, dozens of sets of this type of devices have been installed in China, and all of them have been successful. Coal gasification in foreign countries is mainly used to produce fuel gas and cycle power generation. The ...

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Problems solved by technology

[0004] At present, due to the constraints of coal quality, water resources and environmental protection and other factors, the suspended solids, alkalinity and hardness in the gray water of the coal gasification system continue to increase, which makes the scaling and blockage of the entire coal gasification system increasingly serious, seriously affecting the coal gasification system. The long-term continuous and stable operation of the coal gasification system also causes a large amount of drainage and replenishment water in the coal gasification system. Therefore, in addition to the conventional flocculation and sedimentation and scale inhibition and dispersion treatment of the black ash water of the coal gasification system, a method to reduce the hardness of the ash water in the coal gasification system and significantly There is a very strong necessity and urgency for the complete set of treatment process to reduce the amount of drainage outside the system

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