Membrane coal gasifier process water resource utilization process

Abstract

The invention discloses a membrane coal gasifier process water resource utilization process which comprises the following steps: process water is firstly subjected to three-stage flash evaporation treatment and then enters a buffer settling tank for preliminary settling, supernate in the buffer settling tank is conveyed to a membrane device through a pump, and waste residues are discharged from the bottom of the tank; supernate entering a membrane device is treated and then enters a next-stage softening tank, water produced at a concentrated water end of the membrane device flows back to the buffer settling tank, meanwhile, the other concentrated water end of the membrane device is connected with a slag removal device to achieve indirect slag removal, and water produced by the slag removal device also flows back to the buffer settling tank; and a softening tank treats high-salinity and high-hardness water and then recycles the treated high-salinity and high-hardness water to an evaporation hot water tower or a coal gasification furnace ash water system, and recycled water is recycled to an inlet of the flash tank for recycling. According to the process, colloids, suspended solids and solids are separated, no medicament is added, the operation cost is reduced, and the effluent quality is stable.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to a water resource utilization process of a membrane method coal gasification furnace process. Background technique [0002] The coal chemical industry is a key development industry in my country. Its core device is the coal gasifier, and the coal gasification process water system is the main facility to ensure the safe and stable production of the coal gasifier. The coal gasifier produces a large amount of process water during the production process, which has high temperature, High pressure, high turbidity, high suspended solids, high solid content and other characteristics; Generally, the process water containing high hardness, high alkalinity, high ammonia nitrogen and high COD is treated by multi-stage flash evaporation, chemical and gravity sedimentation. Need to add high-temperature flocculant, coagulant, dispersant, scale inhibitor, etc., there are problem...

AI Technical Summary

Problems solved by technology

[0002] The coal chemical industry is a key development industry in my country. Its core device is the coal gasifier, and the coal gasification process water system is the main facility to ensure the safe and stable production of the coal gasifier. The coal gasifier produces a large amount of process water during the production process, which has high temperature, High pressure, high turbidity, high suspended solids, high solid content and other characteristics; Generally, the process water containing high hardness, high alkalinity, high ammonia nitrogen and high COD is treated by multi-stage flash evaporation, chemical and gravity sedimentation. Need to add high-temperature flocculant, coagulant, dispersant, scale inhibitor, etc., there are problems such as high consumption of chemicals, unstable effluent quality, large amount of wastewater discharge, and high difficulty in treatment. This is an objective production problem in the industry and has been troubled for many years. The coal chemical industry also restricts the long-term stable operation of the coal gasifier, which in turn affects the economical operation of the coal gasifier

[0003] In the traditional coal chemical industry, the process water of coal gasifier is firstly treated with chemical agent (flocculant), then settled, and finally treated with slag removal device; after this method, there are the following problems: (1) High suspended solids in water : After treatment, the concentration of suspended solids in the water quality is high, the water quality is poor, and the secondary recycling will cause a certain degree of damage to the system equipment, such as causing blockage of the nozzle, uneven water output, and failure to achieve the purification effect of the process, etc.

(2) High hardness in water: water hardness reaches above 1600-2000mg / l, which can not only induce the formation of calcium carbonate and magnesium scale, but also soften part of the scale, gather together and adhere to the pipe wall, and solid suspended matter It is also easy to deposit in pipelines and equipment, resulting in more serious fouling of equipment pipelines

(3) Due to the above reasons, in order to ensure the stability of the system, a large amount of fresh water can only be continuously injected to increase the external drainage, which increases the load of the sewage treatment system

(4) The sludge dewatering equipment has a large load. Due to the large amount of water, a large amount of flocculant and dispersant are added to the water, which limits the processing capacity of the filter press equipment.

(5) High-speed scouring, large air resistance, resulting in reduced equipment life and reduced strength

Images