DD155451A1 - DEVICE FOR THE CONTINUOUS TEMPERING OF BROWN COAL - Google Patents

Abstract

The invention relates to a device for the Entwaesserung of lignite and related substances, such as peat, by heat treatment under pressure. In the cylinder-shaped, directly or indirectly heatable reactor, which has a conical lower part, the granulated coal is treated in countercurrent with a fluid heat carrier at elevated pressure and elevated temperature. After completion of the drainage, the coal is discharged by means of a screw, depending on the pressing pressure, either charcoal accumulates in crumbly form or solid moldings are formed.

Description

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Title of the invention

Apparatus for the continuous dewatering of lignite

Field of application of the invention

The invention relates to a device for dewatering lignite and related substances, such as peat u "a ,, by heat treatment under pressure,

The device can be used in plants which have the aim of dewatering and hydrothermal treatment of brown coal or related products. The final products are suitable for use in lignite high temperature coking, smoldering, pressure gasification, coal extraction as well as for direct energy use.

Characteristic of the known technical solutions

It is known _{# to} carry out the dewatering of lignite in an autoclave at elevated temperature · The pressure heat treatment takes place either with direct contact of the coal with

Saturated steam (according to the Fleissner principle, DR-PS 181 048; DR-PS 520 369) or direct contact with hot water (according to the VIAG principle; DR-PS 466 617; DR-PS 608 486), wherein mutually charged, parallel switched autoclave can be used.

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A disadvantage of the use of autoclaves proves that the procedure is discontinuous and the throughput of coal - due to the time and energy consuming heating and cooling of the apparatuses - is relatively low. In addition, only lumpy coal is used and the autoclave is a partial grain disintegration and bridging the coal.

Furthermore, some attempts are known to carry out the dewatering of lignite in tubular reactors "According to DDR PS 6 219 tubular reactors are used for this purpose, in which there is a built-in screw, which is used to transport the coal within the reactor ·

When using tubular reactors with built-in screw, which also also have a sieve plate over which the coal is discharged before discharge (AU-PS 32 607/68), although the water separation is improved, but the separated water must then in addition to the dust over lead a hydrocyclone ·

Another technical solution using an indirectly heated tubular reactor has been described by BR ₀ Stanmore and AR * Boyd ("Continuous Dewatering of Victorian Brown Coal", 4th Hatl. Chem. Eng. Conf., Adelside , Austral., 1976). To carry out the process, a coal slurry is pressed into the reactor by means of a screw. The resulting carbon molds fall on a sieve belt located in the pressure vessel and are dewatered due to the prevailing temperature and the pressure. The discharge of coal from this pressure vessel is carried out by two rotary valves.

The sensible heat of the expelled water is partially used in this solution by the water is expanded and the steam generated thereby is fed to the heat exchanger. Despite the high cost involved in this technical solution no perfect countercurrent and only a small utilization of the sensible heat of the expelled water is achieved.

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Object of the invention

The aim of the invention is the development of a device for the continuous dewatering of lignite coal and related substances, in which the coal to be dewatered and the heat transfer medium used are conducted in countercurrent with the water separated from the coal so that the applied energy is optimally utilized.

Presentation of W _e sens of the invention

This object is achieved by a device for the continuous dewatering of lignite in a reactor by hydrothermal pressure treatment in countercurrent by erfindungsgeinäß in countercurrent in the cylindrical, directly or indirectly heated reactor, aer a conical lower part has, through the located at the top of the reactor entry Schnekke Granuiiervorrichtung continuously coal fed through a one or more at the bottom of the reactor pipe socket supplied fluid heat carrier at a pressure of 0.3 to 9 MPa and a temperature of 400 to 573 K and the coal after dehydration under pressure by a screw, the is at the lower end of the reactor, is discharged and the fluid heat carrier including the water and the gases are discharged separately at the top of the reactor ·

The reactor can be erected vertically or inclined. Suitable material for the reactor are, in particular, heat-resistant steels or boiler plate. It is advantageous if the granulator device of the coal feed screw has a perforated plate whose bores have a diameter of approximately 10 mm, or is provided with a sieve plate with a mesh size of about · 10 mm.

The coal particles should have a particle size of 0.5 to 10 mm when entering the reactor.

Steam or hot water or hot inert gases or other substances, such as oil, are suitable as heat carriers.

By varying the pressure in the screw, the discharged dewatered coal falls at low pressure in a crumbly structure and at high pressure as solid moldings

From the screw, the compacts pass into a Ausdampfbehälter, in which the coal cools by evaporation of residual water contained in it to 373 K. The released steam is used to preheat the coal ·

The separated from the coal water and the fluid heat carrier and gases produced during the process are removed at the top of the reactor, 'they give off during this process, the majority of their sensible heat to the coal. In addition to the drainage is a. Depletion of the coal of alkali salts and a noticeable increase in the extraction and Schwelausbeute achieved.

The advantages of the device according to the invention are that

- The dewatering of the coal in the reactor can be successfully carried out continuously in countercurrent

- Granules of the same size are generated by the granulation at the end of the entry screw, which is then ensured in the reactor uniform heating within a short time

by the variation of the pressure in the discharge screw, the coal can be obtained crumbly or as solid moldings,

Exemplary embodiments Example 1

The device (see Fig. 1) consists of. a vertical or inclined, cylindrical reactor (4) with a conical lower part, the upper part of which is connected by means of an insertion screw (3) with a coal bunker (2). At the bottom of the reactor are pipe socket (7) for the supply of the heat rage rs. At the end of the conical

Reactor bottom part is a discharge screw (5), which connects the reactor with a flash vessel (9), at the upper part of a line for the expansion steam (11) and at the lower part of a rotary valve (10) are arranged. The water level in the reactor (4) is maintained via a level control (6) »The desired reactor pressure is set by the resulting gases (13) via a pressure control device (8) are derived.

Example 2 (see Fig, I):

The comminuted coal (1) passes through a feed bunker (2), in which it is preheated by flash steam to 373 K, into the feed screw (3) _# which conveys the coal into the reactor (4). In the lower part of the reactor, a temperature of 400 K to 573 K is generated by blowing in steam, depending on the desired degree of dewatering. The pressure in the reactor is maintained between 0.3 and 9 MPa depending on the temperature used. Coal is discharged through a screw at the bottom of the reactor. As it is transported through the reactor, it is warmed in countercurrent with the steam or its condensate and the water separated from the coal. It passes with the prevailing in the lower part of the reactor temperature in the discharge screw (5) and can be pressed by a high pressure in the screw directly to solid formations at pressures between 2 and 100 MPa, are. For the production of such moldings, a temperature between 500 K to 550 K is favorable. The discharged coal enters a Ausdampfgefäß (9), in which there is atmospheric or a weak overpressure. In the evaporation vessel, the water in the coal or on its surface evaporates, whereby the temperature of the coal is reduced to 373 K. The relaxation steam is used for preheating the coal in the feed bunker (2). The expelled water and the condensate of the heating steam are drawn off at the top of the reactor and used for energy purposes by known methods. The level of the water is kept constant via a regulating device (6).

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hold. The resulting in the reaction gases, which consist mainly of CO ₂ , H ₂ S and small amounts of CO, H ₂ and hydrocarbons are withdrawn from the top of the reactor, while maintaining the pressure in the reactor via a control (8) · The coal can be discharged from the evaporation vessel via a rotary valve.

Claims (6)

t 21908 claims of the invention 1 device for the continuous dewatering of lignite in a reactor by hydrothermal pressure treatment in countercurrent, characterized in that in countercurrent in the cylindrical, directly or indirectly heated reactor having a conical lower part, continuously through the located at the top of the reactor feed screw with granulator Coal is fed to a fluid heat supplied by one or more pipe stubs located at the lower part of the reactor, at a pressure of 0.3 to 9 MPa and a temperature of 400 to 573 K, and the coal, after dehydration, under pressure by a screw, which is located at the lower end of the reactor, is discharged and the fluid heat carrier including the removed water from the coal and the gases are discharged separately at the top of the reactor » 2. Apparatus according to item 1, characterized in that the reactor is vertical. « 3 «Device according to item 1, characterized in that the reactor is placed inclined · 4 »device according to item 1, characterized in that the granulating device is provided at the entry screw with a perforated or sieve plate. 5 · Device according to item 1, characterized in that as heat transfer medium, such as hot water, water vapor, hot inert gases or other substances, such as oils, use * 6, device according to point 1, characterized in that the pressing pressure in the screw, through which the dewatered coal is discharged, can be adjusted and varied · For this 1 page drawings