Dewatering drying method for fine slag slurry in coal gasification system and dewatering drying system used by dewatering drying method

Abstract

The invention discloses a dewatering drying method for fine slag slurry in coal gasification system, which comprises the following steps that (a) the fine slag slurry produced by the coal gasification system is pre-dewatered by a pre-dehydration and concentration device to obtain the concentrated fine slag slurry; (b) a waste heat resource produced by the coal gasification system exchanges heat with air for heating the air into hot air; (c) the concentrated fine slag slurry and the hot air are fed into a spray dryer at the same time, so that heat and mass transfer is carried out by the direct contact between the concentrated fine slag slurry and the hot air in the spray dryer, and after most of the water is removed, the concentrated fine slag slurry flows out at the bottom and becomes dry fine slag. The invention also discloses a dewatering drying system used by the method. According to the method, the waste heat resource produced by the coal gasification system is used for heating the air, and then the heated hot air is used for drying the concentrated fine slag slurry by a spray dewatering drying technology, so that the waste heat resource can be fully utilized, the equipment cost and the influence on the site environment can be reduced, and the discharged dry fine slag can be further utilized directly.

Description

technical field [0001] The invention relates to the technical field of processing fine slag slurry in a coal gasification system, in particular to a dehydration and drying method for fine slag slurry in a coal gasification system and a dehydration drying system used therefor. Background technique [0002] In the coal gasification system, coal is transformed into fuel gas or chemical synthesis gas through entrained flow gasification, which contains a large amount of fly ash that needs to be purified and removed. At present, the relatively mature synthesis gas purification process is wet purification, which uses water to quench and wash the synthesis gas to remove fly ash and acid gas in the synthesis gas. The wet purification process will produce a large amount of slag water (black water). The slag water is usually concentrated by flash evaporation and sedimentation to obtain a fine slag slurry, and a large amount of low-pressure flash steam will be generated during the conce...

AI Technical Summary

Problems solved by technology

At present, the low-pressure flash steam generally directly uses a large amount of circulating cooling water for condensation. On the one hand, it needs to consume a large amount of cooling water; The efficiency is usually low, which reduces the waste heat utilization rate of the low-pressure flash steam, so the low-pressure flash steam needs to be further rationally utilized to reduce the energy consumption of the gasification system and improve the energy utilization efficiency of the device

[0003] Dry fine slag can be obtained by dehydrating the fine slag slurry obtained from the concentration of slag water. The dehydration process of fine slag slurry generally adopts mechanical filtration. The mechanical filtration unit occupies a large area, and the actual operation of the industry is poor at present. There are big problems in the long-term operation of the device; after mechanical filtration, the water content of the fine residue filter cake is between 50% and 60%, and the dehydration effect is poor, resulting in poor sanitation conditions in the filter system workshop and related sites such as fine residue transportation and storage

In addition, the fine slag has high carbon content and high combustible content, which has certain use value and can be used as boiler or other raw materials. However, the high water content of the filter cake causes certain difficulties for the subsequent reuse of fine slag, and cannot be directly As a boiler fuel, fine slag with high water content also has many inconveniences in transportation and storage, so further dehydration and drying are required for the fine slag to be recycled.

[0004] In view of the above problems, it is necessary to propose a new technical solution to solve the technical problems of the above-mentioned low utilization rate of waste heat and drying treatment of fine slag slurry

Images