RU2624163C1 - Method for reducing coal humidity during its benefication - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for reducing coal humidity during its benefication involves heating the coal mixture, moved by the scraper conveyor by direct contact with the surface of this conveyor, while simultaneously forcing the evaporated moisture out of the heating zone. Only a grade of coal with a particle size from 0.5 to 13 mm is exposed to heating, the surface temperature is controlled in the range from 150 to 250°C, and the speed of moving the working branches of the scraper conveyor is from 0.3 to 1.0 m/s, depending on the percentage of coal of different grades in the initial coal mixture, as well as on the actual humidity parameters of at least two coal grades with a particle size up to 0.5 mm and from 0.5 to 13 mm after their benefication.

EFFECT: method allows to efficiently and safely bring the final moisture content of the coal concentrate to the conditioned without the organization of a separate technological process.

2 cl, 1 dwg

Description

The invention relates to the coal industry and is intended to produce coal concentrate with predetermined moisture content parameters.

One of the obstacles to increasing the calorific value of supplied coal is moisture. The maximum mechanical dehydration of the concentrate during its enrichment in all engine classes using modern high-energy vibrating screens with a separation factor of 4.5G, vibration and sedimentation-filtering centrifuges in most cases can reduce the external moisture of the final concentrate to 6-7%.

However, depending on the granulometric composition of coal (for example, with a larger percentage of small to large classes), its brittleness and internal humidity, in certain cases, achieve conditioned concentrate humidity (not more than 9% in summer and not more than 7% in winter) without using thermal drying is not possible.

 Known and currently used methods of thermal drying have a common significant drawback: they are a separate technological process that requires additional: equipment (often complex and expensive), capacities and production facilities.

Thus, a known method of drying coal (see patent application RU 2007116728, IPC C10L5 / 00, publication date 11/20/2008), containing the following stages:

(a) providing a heat treatment unit in which the product is received and which includes devices for receiving at least two sources of heat to be applied to the product;

(b) providing a first heat exchanger operably connected to the heat treatment unit;

(c) supplying a first source of waste heat to the first heat exchanger, the heat contained in the first source of waste heat being supplied to the heat treatment unit as one of the heat sources;

(d) providing a second heat exchanger operably connected to the heat treatment unit;

(e) supplying a second source of waste heat, the type of which is different from the type of the first heat source, to a second heat exchanger, the heat contained in the second source of waste heat being supplied to the heat treatment unit as a second heat source;

(f) keeping the product inside the heat treatment unit under the combined action of the first and second heat sources at a temperature and for a time that are sufficient to provide the necessary degree of heat treatment;

(g) unloading the product from the heat treatment plant.

The known method is low-tech because it requires at least two different heat sources and is a separate process that requires a complex production line.

A known method of drying coal (see patent application RU 2013126220, IPC C10L5 / 00, publication date 12/20/2014), comprising contacting moist coal fines with at least one water-collecting material, where the water-collecting material includes activated aluminum and, according to at least a portion of the water present in the mixture becomes bound to the water-collecting material.

The main disadvantages of this method are:

- the need for introducing into the coal volume the required water-collecting material to collect moisture, moreover, for more effective moisture removal, it is desirable to mix such material with a coal mass;

- the need for separation of the water-collecting material and coal after binding moisture and the subsequent removal of the water-collecting material.

In addition, depending on the initial moisture content of the coal mass, it may be necessary to conduct several cycles of application of the method (due to the fact that the amount of moisture that a certain amount of water-collecting material can bind is finite and limited by the physical characteristics of the latter).

A known method of drying dispersed (bulk) materials (see patent RU 2549394, IPC F26B 3/20, 3/30, F26B11 / 10, published 04/27/2015), which is carried out inside a vertically mounted cylindrical tank, the bottom of which is heated from the outside directionally -focused radiation in the near infrared region, wet bulk material is periodically poured into the container on the bottom, dried, heated and periodically removed (poured out) of the container, the bottom or the entire container is mesh or perforated, heating the bottom of the bottom or days from the bottom, and the side surface outside along the generatrix to a predetermined temperature, rotating the container relative to its axis, and the initially moistened material to be dried is continuously poured into the hollow stationary pipe, which is installed vertically inside the container coaxially with a uniform gap between the outer surface of the pipe and the inner cylindrical surface of the container so that the gap between the lower end of the pipe and the bottom of the tank is less than the gap between the outer surface of the pipe and the inner cylindrical surface the capacity of the container, while the material inside the pipe is moved down to the middle (to the center) of the heated bottom, from this middle the material is moved along the surface of the bottom from its middle to its edges and further up between the cylindrical wall of the rotating container and the outer surface of the fixed pipe, and near the top the edges of the container on top of the dried material is captured by the suction torch of the pneumatic conveying device and the dried material is continuously removed from the container, in addition, a uniformly uniformly placed outside pipe flat or curved blades in uneven or uneven rows along the length of the pipe, ensuring the interaction of these blades with the material to be dried during its rotation together with the container by tedding the material, and at the same time, the rate of continuous supply of the material to be dried inside the pipe, the rate of continuous removal of the dried material from the container, rotation speed capacity and heating temperature are set, controlled and maintained in automatic mode.

The implementation of the known method requires special equipment that cannot be inserted into existing technological complexes.

A known method of drying using a device for drying ore materials, mainly coal (see patent RU 127437, IPC F26B17 / 04, published 04/27/2013), adopted as a prototype, in which the drying of coal is as follows: hot water passing through the channels in the bottom of the pan of the scraper conveyor, heats it evenly, and the material (coal) moving along the heated pan is drained. At the same time, conveyor scrapers carry out tedding of coal, which additionally accelerates the process of removing moisture from coal and contributes to its more uniform drying.

Using this method improves the safety of drying coal and does not require the installation of devices for cleaning flue gases.

However, the drying efficiency is low due to the limitation of the maximum temperature of the coolant (no more than 70-80 ° C), loss of thermal energy in the pipelines and during heating itself (at least half of the heat is removed from the bottom of the pan without contacting the coal mass).

In addition, in the case of incorporation into finished production lines, serious problems arise for a centralized coolant supply (due to the huge number of elements involved in the coal enrichment process through which a piping system must be drawn).

The task to be solved by the claimed method is aimed is the guaranteed reduction in the humidity of coal concentrate to the normative value directly at the enrichment stage (without organizing a separate technological process).

The technical results of the proposed solution are: moisture removal efficiency, environmental friendliness, explosion and fire safety, manufacturability.

Technical results are achieved by the fact that in the method of reducing the moisture content of coal during its enrichment, including heating the coal mixture moved by a scraper conveyor by direct contact with the surface of this conveyor while simultaneously forcing the evaporated moisture from the heating zone, only a class of coal with particle sizes is heated from 0.5 to 13 mm, the surface temperature is regulated in the range from 150 to 250 ° C, and the speed of movement of the working branches of the scraper conveyor is from 0.3 to 1.0 m / s, depending on the percentage the total content of coal of different classes in the initial coal mixture, as well as the actual moisture parameters of at least two classes of coal with particle sizes up to 0.5 mm and from 0.5 to 13 mm after their enrichment.

In this case, in the case of separation of a class of coal with particle sizes from 0.5 to 13 mm during enrichment into subclasses, only a subclass of coal with particle sizes from 0.5 to 3.0 mm is heated.

The claimed technical solution is illustrated by the drawing, which schematically shows a zone of humidity reduction, built into the processing line for coal enrichment.

   The coal enrichment line includes coal separation zone 1 into classes, coal transportation lines of each class 2, 3, 4 into coal processing zones 5, 6, 7, respectively, and coal transportation lines 8, 9, 10 of each class after processing into the storage zone 11. At the same time, in the middle-class coal transportation line 9, a moisture reduction zone 12 is built in, including a scraper conveyor 15 with a surface 14 in which the heating elements 17 are installed, which are installed in the heat-insulating casing 13, with heating elements 17 installed, and are powered by an external power supply 18.

The implementation of the proposed method is as follows.

The process of coal enrichment initially involves the separation of the coal mixture into classes, conventionally called: “large” - with particle sizes above 13 mm, “medium” - with particle sizes from 0.5 to 13 mm and “small” - with particle sizes up to 0, 5 mm. In addition, in some processing plants there is the possibility of additional separation of the "middle" class into 2 subclasses "a" and "b" with particle sizes "a" - from 0.5 to 3.0 mm and "b" - from 3 to 13 mm This separation is carried out in zone 1 and then the coal of each class is transported along lines 2, 3, 4 to zones 5, 6, 7 of the enrichment of each class, respectively. It should be noted that this separation is due to the fact that for the enrichment of each class of coal they use their own methods: for “large” - heavy separation, for “medium” - deposit, for “small” - flotation.

In the materials of this application, the terms “large class”, “middle class”, “small class”, as well as subclasses “a” and “b” are interpreted in accordance with the particle size ranges indicated in the previous paragraph.

After enrichment, coal of each class is transported via lines 8, 9, 10 to storage zone 11. The middle class coal transported through line 9 enters the case 13 of the humidity reduction zone 12, where it moves along the surface 16 and is heated by it, because the heating elements 17 are placed in it. During the heating process, the moisture contained in the coal evaporates into the internal volume of the case 13 and subsequent removal through the hole 14 from the zone 12. The implementation of the housing 13 heat-insulating avoids heat loss in the process of reducing humidity and thereby increases the efficiency, and the execution of the conveyor 15 scraper provides additional effective mixing of coal during the movement in zone 12 and, accordingly, its more uniform heating and more efficient evaporation of moisture from it.

The necessary power consumption is provided by supplying the heating plates 17 from an external power supply 18. This also provides constructive simplicity of installation, which ensures the implementation of the method, and allows it to be integrated into the existing production line of any processing plant without any difficulties.

The control of the speed of the conveyor 15 and the intensity of heating of the surface 16 is carried out in accordance with the moisture indicators of each class of coal after leaving the enrichment zones. For this, humidity sensors can be installed in the areas of exit from zones 8, 9, 10 of enrichment. However, since real moisture indicators of large-class coal after heavy separation are stable, there is no strict need for their measurement, it is sufficient to control the moisture content of medium and small-class coal.

In cases where there is an additional division of middle-class coal into subclasses at the processing plant, a moisture reduction zone 12 is built into the transportation line that moves subclass “a” of middle-class coal with particle sizes from 0.5 to 3.0 mm, making the claimed method with respect to only this subclass.

According to the results of testing the proposed method at the Chernigovskaya PF, it was possible to achieve an additional decrease in the total humidity of the coal concentrate by 3.4% without changing the overall technological sequence of actions on the PF.

The inventive method of reducing the moisture content of coal in the process of enrichment allows you to effectively and safely bring the final moisture content of coal concentrate to conditional without organizing a separate process.

Claims (2)

1. A method of reducing the moisture content of coal during its enrichment, including heating the coal mixture transported by a scraper conveyor by direct contact with the surface of this conveyor with simultaneous forced removal of the evaporated moisture from the heating zone, characterized in that only the class of coal with particle sizes from 0.5 to 13 mm, the surface temperature is regulated in the range from 150 to 250 ° C, and the speed of movement of the working branches of the scraper conveyor is from 0.3 to 1.0 m / s, depending on the percentage of coal p znyh classes in the initial mixture of the coal and the actual humidity parameters, at least two grades of coal with a particle size up to 0.5 mm and from 0.5 to 13 mm after their enrichment. 2. The method according to p. 1, characterized in that the heating is subjected exclusively to a subclass of coal with particle sizes from 0.5 to 3.0 mm

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