EP3181664A1 - Method and installation for continuous dewatering of water-containing goods, especially for dewatering brown coal - Google Patents

Abstract

It is a method for the continuous dewatering of water-containing material, in particular for dewatering lignite, wherein the material to be dewatered is first preheated in a preheater (9) and wherein the preheated material 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

Description:

The invention relates to a method and a system for the continuous dewatering of water-containing material, in particular 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, consists, 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.

Incidentally, one knows from the DE 10 2008 012 873 A1 a process for the treatment of lignite coal using screw presses, extruders or expanders. DD 608 B2 describes a method for improving brown coal briquettes by treating loose dry brown coal with a vapor-air mixture.

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 under condensation the Lignite warms. 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 principle known knowledge that the good, especially lignite, particularly efficient in a continuous process with a continuously operating Dewatering press dewatering, with 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 requires a certain processing time. 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 in the dewatering press in the course of dewatering resulting press vapors (which is a vapor-air mixture) sucked off and the preheater are supplied 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. For this purpose, it has two endless conveyor belts circulating around each deflection rollers, between which a passage gap is formed for the material to be preheated. 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, via a mixture line with the preheating be connected, 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 Anfahrprozesses not yet sufficient amounts of press broths available and then a steam-air mixture of 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 ,

Fig. 1

eine erfindungsgemäße Anlage zur Entwässerung von Braunkohle in einer vereinfachten Seitenansicht,

Fig. 2

einen vergrößerten Ausschnitt aus der Anlage nach Fig. 1,

Fig. 3

schematisch vereinfacht eine Vorwärmeinrichtung der Anlage nach Figuren 1 und 2 in einem Querschnitt durch die Matte M.

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

Fig. 1

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

Fig. 2

an enlarged section of the plant after Fig. 1 .

Fig. 3

schematically simplifies a preheating the plant after FIGS. 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 plant is a continuous dewatering press 1, in which the brown coal is dehydrated mechanically-thermally using pressure and heat. Such a dewatering press 1 is formed in the embodiment as a double belt press. It has an upper heatable press plate 2 in the press upper part and a lower heatable press plate 3 and endlessly rotating press belts 4 in the lower press part, these press belts 4 being guided around deflection rollers 5. The pressing belts 4 are with the interposition of Wälzkörperaggregaten 6, z. As rolling rods, supported on the press plates 2, 3, 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, for. B. hydraulic pressure cylinders 8 applied, 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 dewatering press 1 is preceded by a pre-heater 9, with respect to the working direction A, with which the lignite or a lignite-scattered mat is preheated to the subsequent Optimize drainage process. The preheater 9 is formed as a continuous preheating device 9 in the manner of a preheating, which operates 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, which are guided around deflecting rollers 11, wherein between the sieve belts 10 a passage gap 12 is formed, through which the mat (from eg lignite) to be preheated is led.

It is in Fig. 1 indicated that for the formation of this mat, the brown coal is first crushed in a crushing device 13 and then scattered by means of a scattering station 14 on a conveyor belt 15, wherein the mat thus formed is then supplied to the preheater 9.

In the preheater 9, the brown coal or lignite mat is flowed through by a vapor-air mixture. For this purpose, the preheating 9 on the one hand at least one feeder 16 and a feeder box 16 and on the other hand, a suction device 17, z. B. a suction box 17. Details are in Fig. 2 and 3 recognizable. In the embodiment, a plurality of feed boxes 16 and suction boxes 17 are provided. About the Zuführkästen 16, the vapor-air mixture D is supplied and sucked through the suction through the suction or the suction boxes 17 through the mat. In this case, the vapor fraction in the vapor-air mixture condenses and the air fraction L of the mixture is sucked off via the exhaust hood 17. 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 Fig. 2 directed.

Because according to the invention used in the dewatering press 1 press broths are used for preheating. The dewatering press 1 is provided with (lateral) suction devices 18, via which the press vapors produced in the dewatering press are extracted. Via a vapor line 19, these press broths are fed to a mixing chamber 20. In this mixing chamber 20, the press vapors 19, which are formed as a vapor-air mixture, mixed with live steam, which is supplied via a main steam line 21. This makes it possible to vary the proportion of steam in the vapor-air mixture and thus to adjust the dew point to the desired level, with simultaneous utilization of the resulting in the dewatering press 1 press vapors. The thus mixed steam-air mixture is supplied from the mixing chamber 20 via the mixture line 22 of the preheater 9.

It is in Fig. 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. This means that a first feed box 16 above the mat and a first suction box 17 below the mat and then a second feed box 16 below the mats and a second suction box 17 are arranged above the mat.

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

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

However, if sufficient amounts of press vapors are still not available during a starting process in the dewatering press 1, a steam-air mixture of pure live steam and air is used for the preheating in the preheating device, so that a steam-air Mixture of pure steam is produced by adding air. During this phase, the still occurring in the dewatering press 1 press vapors can be discharged via a bypass line 24. In retracted operation, the vapors extracted from the press are mixed in the mixing chamber 20 by means of live steam supply to the desired dew point.

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

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

Claims (10)

Process for the continuous dewatering of water-containing material, in particular for dewatering lignite,
wherein the material to be dehydrated is first preheated in a preheating device (9) and
wherein the preheated material is dewatered in a continuous dewatering press (1) using pressure and heat,
characterized in that the material to be dehydrated 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) obtained in the course of dewatering press vapors sucked and the preheater (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 startup of the dewatering press (1) is acted upon by a steam-air mixture of live steam and air. Plant for dewatering water-containing material, in particular for dewatering lignite, in particular by a process according to one of claims 1 to 4,
with a preheating device (9), with which the material to be drained is preheated and
with a continuously operating dewatering press (1), preferably with heatable press plates (2, 3) and endless circulating press belts (4) which form a press nip (7) through which the material to be dewatered is passed through for dewatering by means of pressure and heat,
characterized in that the preheating device (9) is designed as a continuously operating preheating device (9), in which the continuous and to be drained Good flows through a vapor-air mixture. Installation 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) rotating conveyor belts (10), z. B. screen belts, between which a passage gap (12) is formed for the material to be preheated. Installation according to claim 5 or 6, characterized in that the dewatering press (1) is equipped with at least one suction device (17) for sucking off the press vapors, wherein the suction device (17) is connected via a vapor line (19) to 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) is connected. Plant according to claim 7 or 8, characterized in that to the mixing device (20) has a Dampfzuführleitung (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 discharging the press vapors, z. B. is connected during a startup process.

Images