Process for indirectly drying brown coal through low-temperature steam and system device of process

Abstract

The invention belongs to the technical field of electric power and the chemical industry, and particularly relates to a process for indirectly drying brown coal through low-temperature steam and a system device of the process. The process includes the following steps of making brown coal enter a drying pipe of a dryer from a raw coal bin through a coal feeder, and injecting the low-temperature steam to the portion outside the drying pipe of the dryer, so that brown coal inside the drying pipe indirectly exchanges heat with the steam outside the drying pipe, and the aim of drying the brown coal is achieved. The system device comprises a rotating sealed feed valve and a steam trap, and therefore dew formation caused when dried coal carries a large amount of water steam and enters an embedded scraper transporter is avoided, the heat utilization efficiency of high-temperature steam and the low-temperature steam is well improved, steam consumption is lowered, resources are saved, and economic benefits are improved.

Description

technical field [0001] The invention belongs to the technical field of electric power chemical industry, and in particular relates to a technique and a system device for indirect drying of lignite by low-temperature steam. Background technique [0002] my country has relatively large reserves of lignite, and the proven storage capacity is about 210 billion tons, accounting for 13% of the national coal reserves. This type of coal has high moisture content (35%-50%), low calorific value, high volatile content, and is prone to spontaneous combustion. Large-scale development and utilization and conversion and utilization as raw materials are greatly restricted. In order to make efficient use of lignite, the most economical method is to dry and dehydrate it first. In the power industry, by reducing the moisture in lignite and increasing the calorific value, the investment in follow-up system equipment (milling, boilers, desulfurization, dust removal, etc.) can be reduced; in the...

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Problems solved by technology

[0003] For lignite drying, there are currently two main methods in China; one is a rotary drum dryer or a fluidized bed dryer that uses flue gas (or hot air) as the drying medium, and the drying medium and lignite are directly contacted for heat exchange drying. The temperature of the lignite drying method should not be controlled. Due to the low ignition point, high volatile content and easy combustion of lignite, the industrial operation safety of this method is not guaranteed; the other is a steam tube dryer that uses steam as the heat source. The temperature is easy to control, the amount of exhausted gas in coal drying is small, and the safe operation is guaranteed. It is the best method for drying large-scale lignite at present.

[0004] Indirect steam drying is adopted in China, and the methods for treating exhaust gas in the drying system are different; some use electrostatic precipitators, which have low resistance and no induced draft fan, and the drying system cannot be controlled and adjusted; wet dust collectors are used, coal powder is deposited in water, and sewage treatment air crash

[0005] The Chinese invention patent application with the application number 201210563814.7 discloses a lignite drying process and device. In this process: part of the low-temperature steam has no time to release heat and is discharged into the condensation tank, causing cavitation of the condensate pump and reducing heat utilization efficiency; dry coal carries A large amount of water vapor enters the buried scraper conveyor to condense, causing the buried scraper conveyor to block coal; the lignite particle size is small, the fluidity is poor, the feed capacity of the dryer is low, and the processing capacity is small

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