DE102015121869A1 - Process and plant for the continuous dewatering of water contained material, in particular for dewatering lignite - Google Patents

Abstract

It is a process for the continuous dewatering of water contained material, in particular for dewatering lignite, wherein the material to be dewatered is first preheated in a preheater (9) and wherein the preheated good in a continuous dewatering press (1) using Pressure and heat is drained. The method is characterized in that the material to be dewatered in the continuous preheating device (9) is flowed through by a vapor-air mixture.

Description

The invention relates to a method and a system for the continuous dehydration of water contained good, especially for dewatering lignite, wherein the material to be dewatered is first preheated in a preheater and wherein the preheated material is dewatered in a continuous dewatering press using pressure and heat becomes.

The material to be dewatered is particularly preferably coal, in particular lignite, which is treated as part of a mechanical-thermal dewatering process (MTE). Because raw lignite usually has a high water content and the burning of such humid brown coal in power plants is energetically and environmentally unfavorable. Therefore, the dewatering or predrying of lignite before burning is of particular importance. The invention preferably relates to a process for dewatering lignite in a continuous dewatering press, the z. B. is designed as a double belt press, the brown coal usually first crushed and applied as a spreading material mat on a conveyor or scattered and this grit mat is then first passed through a preheater and then through the dewatering press and thereby dehydrated mechanically-thermally. In a double belt press is a continuous press, which in its basic structure of a lower heated press plate or hot plate, an upper heated press plate or hot plate and each endless circulating press belts, z. B. steel strips, which, with the interposition of Wälzkörperaggregaten, z. B. Roll bars, are supported against the press plates and form a press nip.

A method and a system of the type described above are z. B. from the DE 10 2014 016 867 B3 known. Before the press, in which the spreadable material is subjected to pressure and heat, a pre-treatment station can be provided. This can be used for smoothing, for trimming, for steaming, for preheating, for pre-compacting and / or for leveling the spreading material mat. This is intended to compensate for slight unevenness in the scattering with physically or chemically different scattered particles.

Alternative methods of reducing the water content of lignite or sludge are described in US Pat DE 195 35 315 A1 and the DE 195 37 286 B4 described.

In the DE 196 06 152 A1 describes a method for reducing the water content of hydrous, granular lignite under the action of thermal energy and pressure on the surface beetmäßig distributed material in which the brown coal is subjected to a mechanically applied initial surface pressure, which is below the maximum occurring in the process surface pressure and in the the lignite thermal energy is supplied by steam, which heats the lignite under condensation. Thereafter, the surface pressure is increased to such an extent that the water contained in the heated brown coal is squeezed without further steam supply. Before the supply of water vapor, the lignite is preheated by waste heat and used as a waste heat source in the process of lignite pressed hot water. It is envisaged that the hot water is fed directly to the beddish distributed lignite with uniform application and pressed through the brown coal. The drainage takes place in a conventional plate press. A similar procedure is used in the DE 196 35 086 C1 described.

Alternatively, the preheating of lignite by pure saturated steam is known from practice, which is used in power plant processes for drying. Although the known methods have basically proven themselves, they are capable of further development in terms of their efficiency and cost-effectiveness. - This is where the invention starts.

The invention has for its object to provide a method for the continuous dewatering of water contained good, in particular for dewatering of brown coal, which is characterized by particularly high efficiency and efficiency.

To solve this problem, the invention teaches in a generic method of the type described above that the material to be dewatered is flowed through in a continuously operating preheating of a vapor-air mixture.

The invention is initially based on the fundamentally known finding that the material, in particular brown coal, can be dewatered particularly efficiently in a continuous process with a continuously operating dewatering press, wherein such a dewatering press is preferably designed as a double-belt press. As part of the mechanical-thermal dewatering in the continuous double belt press to be drained Good, z. As the lignite, are heated to a certain temperature level at which the process is particularly efficient. This sets a certain processing time ahead. The invention is based on the recognition that this processing time can be shortened in the continuous dewatering press when the material to be drained z. As the lignite is preheated before entering the dewatering press. Thus, the throughput can be increased with the same press length or vice versa achieve the same throughput at a lower press length.

According to the invention, a particularly efficient preheating now takes place, in that the material is flowed through by a vapor-air mixture, because in such a process, the steam-air ratio can be varied and consequently adjusted, and thus the dew point of the steam-air ratio can be specifically controlled. Pretend mixture.

The invention makes use of basically known knowledge from the field of the production of wood-based panels, because the preheating of wood-based materials in the course of the production of wood-based panels using a vapor-air mixture is known and has proven excellent in practice. The scattered mat is flowed through by a vapor-air mixture and thereby heated very quickly, completely and evenly. Corresponding methods are for example in the DE 196 35 410 A1 . DE 102 42 770 A1 . DE 10 2008 039 720 B4 . DE 197 01 596 C2 described. However, such developments did not affect the drainage of lignite.

In addition to the possibility of using a steam-air mixture to heat the lignite or other material to be dehydrated quickly, completely and evenly, it is advantageously possible to vary the steam-air ratio and thus specifically targeted dew points in the manner described to achieve condensation.

By special efficiency, a preferred embodiment of the invention is characterized in which the obtained in the dewatering press in the course of dewatering press vapors (which is a vapor-air mixture) sucked off and the preheater are fed as a vapor-air mixture , Thus, steam-air mixtures can be used, the concept incurred in the process in the (open) dewatering press. These press broths are sucked off, if necessary cleaned (eg with electrostatic precipitators and cyclones) and fed to the preheating device, which is also designed as a continuous preheating device, so that overall a continuous process is realized. This further increases the thermal efficiency of the drainage by avoiding thermal losses through the use of the steam-air mixtures resulting from the dewatering process in the dewatering press.

The ability to vary the composition of the vapor-air mixture to adjust the dew point is of particular importance. This can be when using the press broths z. B. be done by the press broths to adjust the dew point with (separate) steam, z. B. live steam can be mixed. It can be saturated steam. Optionally or additionally, however, it is also within the scope of the invention, the press vapors for adjusting the dew point with air, z. B. fresh air to mix.

In continuous operation, the steam-air mixture of press vapors and optionally admixed (fresh) steam and / or admixed air is therefore generally used for preheating. Optionally, it is possible to work with a vapor / air mixture of steam (eg fresh steam) and air during startup of the dewatering press. The invention is based on the recognition that significant amounts of press vapors from the dewatering press may not yet be available during the start-up process. In this phase of the process, the preheating is fed independently of the press vapors with a vapor-air mixture, z. B. charged with pure live steam, which is adjusted in an upstream mixing chamber to the desired dew point by adding air. In retracted operation, the press vials extracted from the press are also mixed to the desired dew point in this mixing chamber, z. B. by means of live steam supply.

The invention also relates to a plant for dewatering of water-containing material, in particular for dewatering lignite, with a preheater, with which the material to be dewatered is preheated and with a continuous dewatering press, preferably with heated press plates and endless circulating press belts, the one Forming press nip, through which the material to be drained is passed through for dewatering by means of pressure and heat. This plant is preferably designed and set up for dewatering with the described dewatering process. The system according to the invention is characterized in that the preheating device is designed as a continuously operating preheating device, in which the continuous material to be dehydrated flows through a vapor-air mixture.

The preheating device therefore also operates continuously and is preferably designed as a double belt device similar to a double belt press. To do this, she points two endlessly around each Umlenkrollen circulating conveyor belts, between which a passage gap for the preheated Good is formed. These conveyor belts are designed so that the vapor-air mixture can pass through the conveyor belts. So it can be z. B. act to screen belts. The vapor-air mixture thus permeates the mat of material to be preheated passing through the passage gap in a direction substantially perpendicular to the plane of the mat. For this purpose, the preheating z. For example, one or more feed boxes on one side of the mat (eg, above the mat) and one or more suction boxes on the opposite side (eg, below the mat). Optionally, feed boxes and suction boxes can also be arranged on one side and corresponding suction boxes or feed boxes on the opposite side. In any case, the steam-air mixture for preheating the mat by the conveyor belts, z. B. screen belts, and through the preheated good (eg., Lignite) suck through. The vapor content condenses in the mat, resulting in a particularly efficient preheating. In particular, the air fraction of the mixture is then removed by suction via the mixture suction hood.

An embodiment in which the press vapors produced in the dewatering press are used is particularly advantageous. For this purpose, the dewatering press is equipped with at least one suction device for extracting the press vapors, wherein the suction device is connected via a vapor line with a mixing device in which the press vapors are miscible with steam and / or air. This mixing device, for. B. mixing chamber, may be connected via a mixture line with the preheating, so that the mixed steam-air mixture is supplied via the mixture line of the preheater for preheating. Since the press vapors in the mixing device preferably with steam, for. As live steam, are mixed, to the mixing device is preferably a steam supply line for supplying steam, for. B. for supplying live steam / saturated steam, connected.

Furthermore, it is preferably provided that a bypass line for discharging the press vapors is connected to the vapor line before the mixing chamber. Because if z. B. during the start-up process is still not sufficient amounts of press broths available and then a steam-air mixture of live steam and air is used, can be discharged via this bypass line resulting in the press during startup amount of vapor and z. B. be disposed of.

Overall, the dewatering in a continuous process significantly improves the thermal efficiency of the subsequent lignite burning. According to the invention, the drainage is particularly energy efficient by heat recovery. Energy recovery is energetically particularly efficient because the resulting Brück presses can be used directly as a vapor-air mixture or for producing a vapor-air mixture, which flows through the lignite (or other good to be heated) for the purpose of preheating ,

In the following the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. Show it

1 a plant according to the invention for dewatering lignite in a simplified side view,

2 an enlarged section of the plant after 1 .

3 schematically simplifies a preheating the plant after 1 and 2 in a cross section through the mat M.

In the figures, a plant for the dewatering of water contained Good, especially for dewatering of brown coal is shown. The core of such a system is a continuous dewatering press 1 in which the lignite is mechanically-thermally dewatered using pressure and heat. Such a drainage press 1 is formed in the embodiment as a double belt press. It has an upper heatable press plate in the press upper part 2 and in the press base a lower heatable press plate 3 as well as endless revolving press belts 4 on, with these press belts 4 around pulleys 5 are guided. The press belts 4 are with the interposition of Wälzkörperaggregaten 6 , z. B. roller bars, on the press plates 2 . 3 supported, so that between the press belts a press nip 7 is formed. At least one of the press plates, z. B. the upper press plate 2 is with printing units, z. B. hydraulic press cylinders 8th loaded, which may be supported on the press frame of the press frame. Such continuous presses have long been known, especially in connection with the production of wood-based panels. In the context of the invention, they serve the drainage of z. As brown coal, as well as in the DE 10 2014 016 867 B3 is described.

The drainage press 1 is based on the direction of A A preheating 9 upstream, with which the lignite or a lignite-strewn mat is preheated, to the subsequent dewatering process optimize. The preheating device 9 is as a continuous preheating device 9 designed in the manner of a preheating, which works with a vapor-air mixture. It can be used on the marketed by the applicant "ContiTherm preheating". The preheating device has at least two endlessly circulating sieve belts 10 on, around pulleys 11 are guided, being between the screen belts 10 a pass gap 12 is formed, through which the mat to be preheated (from, for example, brown coal) is passed.

It is in 1 indicated that to form this mat, the brown coal first in a crushing device 13 crushed and then with the help of a scattering station 14 on a conveyor belt 15 is sprinkled, wherein the mat thus formed then the preheater 9 is supplied.

In the preheating device 9 the brown coal or lignite mat is flowed through by a vapor-air mixture. For this purpose, the preheating device 9 on the one hand, at least one feeding device 16 or a feeder box 16 and on the other hand a suction device 17 , z. B. a suction box 17 on. Details are in 2 and 3 recognizable. In the embodiment, several feed boxes 16 and suction boxes 17 intended. About the feeder boxes 16 the vapor-air mixture D is supplied and via the suction device or the suction boxes 17 sucked through the mat. In this case, the vapor fraction condenses in the vapor-air mixture and the air content L of the mixture is via the hood 17 aspirated. Laterally from the mat M can also escape the proportion of air L of the mixture or a vapor-air mixture D and optionally sucked.

Adjust the dew point of the steam-air mixture by mixing the steam on the one hand and the air on the other hand. This will be on 2 directed.

Because according to the invention for preheating in the dewatering press 1 used used press broths. The drainage press 1 is with (side) suction devices 18 over which the press vapors produced in the dewatering press are extracted. About a vapor line 19 These press broths become a mixing chamber 20 fed. In this mixing chamber 20 become the press brothes 19 , which are formed as a vapor-air mixture, mixed with live steam, via a main steam line 21 is supplied. This makes it possible to vary the proportion of steam in the vapor-air mixture and so adjust the dew point to the desired level, while using the in the dewatering press 1 arising press broths. The thus mixed steam-air mixture is from the mixing chamber 20 over the mixture line 22 the preheating device 9 fed.

It is in 2 an embodiment shown in which the mat is flowed through in a first section from top to bottom and in a second section from bottom to top. That means a first feeder box 16 above the mat and a first suction box 17 below the mat and then a second feeder box 16 below the mats and a second suction box 17 are arranged above the mat.

The over the suction boxes 17 from the preheating device 9 extracted gases / vapors become a cyclone 23 fed to the separation of water, so that then on the one hand residual condensate of the extracted by the coal vapors and on the other hand residual vapors are derived, which can be reused in the process.

According to the invention are therefore for the preheating in the preheater 9 the press vapors used with steam and / or air to adjust the dew point in the mixing chamber 20 be mixed.

If, however, during a start-up process in the dewatering press 1 not yet sufficient amounts of press broths are available, a steam-air mixture of pure live steam and air is used for preheating in the preheater, so that in the mixing chamber 20 a vapor-air mixture of pure live steam is produced by adding air. During this phase can be in the dewatering press 1 Nevertheless, resulting press bricks via a bypass line 24 dissipate. In the retracted operation are in the mixing chamber 20 the vapors extracted from the press are mixed by means of live steam supply to the desired dew point.

It is in 2 further indicated that in the vapor line 19 a control flap 25 and a butterfly valve 26 There is also a fan 27 may be provided for the transport of the brothers.

To the press 1 can be followed by other processing facilities, z. B. a chain curtain 28 and / or a crushing device 29 that z. B. below the chain curtain 28 can be arranged.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014016867 B3 [0003, 0025]
• DE 19535315 A1 [0004]
• DE 19537286 B4 [0004]
• DE 19606152 A1 [0005]
• DE 19635086 C1 [0005]
• DE 19635410 A1 [0011]
• DE 10242770 A1 [0011]
• DE 102008039720 B4 [0011]
• DE 19701596 C2 [0011]

Claims (10)

Process for the continuous dewatering of water-containing material, in particular for dewatering lignite, wherein the material to be dewatered first in a preheating device ( 9 ) and wherein the preheated material in a continuous dewatering press ( 1 ) is dewatered using pressure and heat, characterized in that the material to be dewatered in the continuous preheating device ( 9 ) is flowed through by a vapor-air mixture. A method according to claim 1, characterized in that in the dewatering press ( 1 ) aspirated in the course of dewatering press broths and the preheating device ( 9 ) are supplied as a vapor-air mixture. A method according to claim 2, characterized in that the press broths for adjusting the dew point of the steam-air mixture with steam, for. As live steam and / or mixed with air. Method according to one of claims 1 to 3, characterized in that the preheating device ( 9 ) during the start of the dewatering press ( 1 ) is acted upon with a steam-air mixture of live steam and air. Plant for dewatering of water-containing material, in particular for dewatering lignite, in particular according to a method according to one of claims 1 to 4, with a preheating device ( 9 ), with which the material to be dewatered is preheated and with a continuously working dewatering press ( 1 ), preferably with heatable press plates ( 2 . 3 ) and endless circulating press belts ( 4 ), which has a press nip ( 7 ) through which the material to be dewatered is passed for dewatering by means of pressure and heat, characterized in that the preheating device ( 9 ) as a continuous preheating device ( 9 ) is formed, in which the continuous and to be drained Good flows through a vapor-air mixture. Plant according to claim 5, characterized in that the preheating device ( 9 ) is designed as a double belt device and at least two endlessly around each deflection rollers ( 11 ) circulating conveyor belts ( 10 ), z. B. screen belts, between which a passage gap ( 12 ) is formed for the preheated goods. Plant according to claim 5 or 6, characterized in that the dewatering press ( 1 ) with at least one suction device ( 17 ) is equipped for sucking off the press vapors, wherein the suction device ( 17 ) via a vapor line ( 19 ) with a mixing device ( 20 ), in which the press vapors are miscible with steam and / or air. Plant according to claim 7, characterized in that the mixing device, for. B. mixing chamber, via a mixture line ( 22 ) with the preheating device ( 9 ) connected is. Plant according to claim 7 or 8, characterized in that to the mixing device ( 20 ) a steam supply line ( 21 ), z. B. for the supply of live steam, is connected. Installation according to one of claims 7 to 9, characterized in that the vapor line ( 19 ), z. B. in front of the mixing chamber ( 20 ), a bypass line ( 24 ) for deriving the press vapors, z. B. is connected during a startup process.

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