A method for cascade upgrading of lignite

Abstract

The invention relates to a gradient upgrading method for lignite. The gradient upgrading method for the lignite comprises the following steps that (1) the lignite is crushed; (2) equipment improvement is carried out, specifically, upgrading equipment is divided into a drying area and an upgrading area through a partition plate, the deformed material section is reshaped to be rectangular as before through the partition plate, and the flue gas heating efficiency is improved; (3) vapor condensation is carried out, specifically, vapor generated in the drying process is collected and condensed independently, the condensation amount is controlled, and 70% (by volume) of vapor in air is made to be standby; and (4) lignite upgrading is carried out, specifically, pyrolysis gas generated in the upgrading area enters a lifting flue of a cyclone barrel, fine powder of a fine coal bin is leaked from the upper end of the flue, the flowing speed of flue gas in the lifting flue is controlled to be 0.5-1.3 Nm<3> / s, and through downward flowing of the fine powder, heat in the flue gas is recycled and coal tar is adsorbed; the fine powder is dried, and the temperature of the fine powder is increased to 150-250 DEG C; upgraded lignite semicoke is obtained by upgrading the lignite in the upgrading area; and the pyrolysis gas is delivered back to a hot blast heater to support combustion. According to the method, the gradient utilization of the lignite is achieved, and the lignite resource utilization rate is high; and a cooling area is reduced, the drying area and the upgrading area are expanded, and the hour output of the equipment is improved.

Description

technical field

[0001] The invention belongs to the field of coal chemical industry, and in particular relates to a method for cascade upgrading of lignite. Background technique

[0002] Lignite belongs to soft coal. Compared with other coals, lignite has high oxygen content, large changes in ash content and ash melting point, low density, easy spontaneous combustion, and coal powder is easy to explode. my country's lignite is a low-quality fuel with high volatile content (about 50%), high moisture content (about 30%), high ash content (about 30%), low calorific value (about 14MJ / kg), and low ash melting point.

[0003] In recent years, with the worldwide energy shortage and the dwindling of high-quality coal resources, the use of lignite in low-quality coal has gradually attracted attention. However, lignite is prone to spontaneous combustion due to its high moisture content, so upgrading its quality is a prerequisite for its large-scale use. Lignite upgrading means that l...

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