Method for multi-effect evaporation and dehydration of solid material

Abstract

The present invention provides a method for multi-effect evaporation and dehydration of a solid material, which comprises preparation of a plurality of digesters. The digesters are connected in parallel relative to the flow direction of the solid material, and each digester can repeatedly heat, evaporate and dehydrate the solid material step by step from a low temperature to a high temperature according to a time sequence. In the preferential embodiment, at least part of the digesters needs vacuum pumping prior to final discharge.

Description

field of invention [0001] The present invention relates to a method of dewatering solid materials. Background technique [0002] Lignite is a kind of coal with a low degree of coalification. It has a high water content and is easily weathered in the air. It contains a certain amount of primary humic acid, and its volatile content is generally between 45-55%. Due to the high moisture content and low calorific value of lignite, it is easy to weather and spontaneously combust, and the transportation cost per unit energy is high, which is not conducive to long-distance transportation and storage. The thermal efficiency of direct combustion of lignite is also very low. Lignite as a raw material needs to reduce the moisture in the coal to less than 10% in the process of liquefaction, dry distillation and gasification. Therefore, lignite upgrading and processing is called the key to the efficient development and utilization of lignite. The so-called upgrading of lignite means th...

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Problems solved by technology

The cooking device disclosed in the patent CN1989227A has a complex structure, especially wherein the equipment for separating gas, liquid and solid from each other is carried out by a separate liquid separator, which includes a porous rotary table or a porous cone inside the device and The porous tube and the separation table at the bottom of the device, in which only the porous tube plays the role of liquid-solid separation, while the porous rotary table and the separation table seriously occupy the internal space of the device, and the patent requires that the porous rotary table and the separation table can be rotated , it is also necessary to equip the corresponding power equipment and transmission equipment in the device, and make these power equipment and transmission equipment able to withstand the high temperature and high pressure in the device, which further complicates the device

In addition, in this patent, the porous pipe only plays the role of drainage, and the entry and exit of steam depends on the arrangement of multiple steam inlets and steam outlets along the height direction of the device, which also complicates the device

And this patented method does not use the flash steam and hot water produced in cooking to preheat the raw materials, so the raw steam (heat energy) consumption is high (about 2-3 times that of this patented technology)

In addition, the K-fuel technology digester is equipped with upper and lower lock hoppers for continuous cooking and intermittent material feeding (discharging). The material containing lignite passes through the lock valve under differential pressure, and the solid matter in the material will wear the valve greatly; Before the lower lock hopper is discharged, it is difficult to drain the free water first, which will have a negative impact on the quality improvement efficiency

[0006] However, the D-K non-evaporative dehydration technology can only realize semi-continuous operation at present, which affects the production capacity and operation stability of the device, and the water content of the lignite after cooking is still high, which needs to be further reduced

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