System and method for treating low-rank coal

Abstract

The invention discloses a system and method for treating low-rank coal. The system comprises a low-rank coal pulverizing device, a low-rank coal screening device, a lump coal hot-wind dense-medium sorting device, a pulverized coal hot-wind flow sorting device, a clean coal pulverizing device, a forming device, a pyrolysis device and a waste heat recovery device, wherein the lump coal hot-wind dense-medium sorting device is provided with a lump coal inlet, a first hot wind inlet, a solid dense medium inlet, a first clean coal outlet and a first tail gas outlet; the pulverized coal hot-wind flow sorting device is provided with a pulverized coal inlet, a second hot wind inlet, a second clean coal outlet and a second tail gas outlet; the pyrolysis device is provided with a feed inlet, a semi-coke outlet and a pyrolysis oil gas outlet; the waste heat recovery device is provided with a semi-coke inlet and a hot air outlet, the semi-coke inlet is connected with the pyrolysis device, and the hot air outlet is connected with the first hot wind inlet and the second hot wind inlet. By means of the system, the gangue discharging rate of the low-rank coal can be remarkably increased, and therefore the quality and yield of pyrolyzed products in the subsequent pyrolysis process can be improved; moreover, the energy cost can be obviously lowered by recovering waste heat generated in the pyrolysis process and applying the waste heat to the gangue discharging process.

Description

technical field [0001] The invention belongs to the technical field of coal chemical industry, in particular, the invention relates to a system and method for processing low-rank coal. Background technique [0002] my country's coal resources are characterized by rich coal, poor oil, and little gas. The position of coal in my country's energy resources will not change for a long period of time. In coal resources, low-rank coal reserves are abundant. According to the prediction of international geologists, low-rank coal accounts for about 60% of coal resource reserves. It is one of the main energy sources that can be used in the future. It is mainly distributed in Australia, the United States, Russia, and China. , Indonesia, Germany and Eastern European countries, etc. Low-rank coal mainly includes non-caking coal, weakly caking coal, long-flame coal and lignite, etc., which have the characteristics of high moisture, low density, high volatile content, non-caking, strong che...

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Problems solved by technology

[0003] Although the mineral impurities in low-rank coal can be removed by separation, the full contact between coal and water in the process of wet separation increases the moisture content of the coal preparation product, reduces the calorific value of the product, and partially offsets the effect of coal washing. The goals of quality improvement and dehydration are contradictory, and the surface moisture of coal in the process of dry separation at room temperature makes the probability of adhesion between particles high, and the effect of gangue discharge is poor

Although the independent drying and low-temperature carbonization technology can increase the calorific value of low-rank coal to a certain extent, the mineral impurities such as ash and sulfur in the upgraded coal affect the quality of subsequent processed products, and compounds such as sulfur and nitrogen cause pollution to the environment and equipment corrosion

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