EP2675872A1

EP2675872A1 - Generating carbon and combustible gases from brown coal

Info

Publication number: EP2675872A1
Application number: EP12704699.3A
Authority: EP
Inventors: Bernd Schottdorf
Original assignee: European Charcoal AG
Current assignee: European Charcoal AG
Priority date: 2011-02-17
Filing date: 2012-02-15
Publication date: 2013-12-25
Also published as: CN103517969A; WO2012110236A1

Abstract

In a method for obtaining carbon and combustible gases from wet brown coal or dry brown coal which is moistened at the start of the method, the brown coal is caused to pass continuously from top to bottom in the direction of gravity through four zones in a moving bed in a suitable reactor: a first or drying zone, in which the wet or moistened brown coal is dried by ascending hot vapours and gases; a second or pyrolysis zone, in which the dried brown coal is pyrolysed with a high, preferably at least 98% substoichiometric amount of oxygen, to give off pyrolysis gas; a third or flame zone and a fourth or smoulder zone, which together form an ember zone, in which remaining organic and metallic compounds are subjected to oxidization and/or combustion/gasification, with a substantially stoichiometric supply of oxygen, based on the organic and metallic compounds; the uncombusted residue comprises substantially pure - at least about 90% - carbon, which is removed continually.

Description

GENERATION OF CARBON AND FLAMMABLE GASES

BROWN COAL

Field of the invention

The invention relates to a process for the production of carbon and combustible gases from lignite.

Background of the invention

Lignite is the largest German fossil energy source. German brown coal has an average water content of about 50%. Their calorific value is relatively low, usually at most 28.5 MJ / kg, while that of hard coal is in the range of 35 MJ / kg.

Lignite is usually dried and burned to burn in house fire

Lignite briquettes processed. Dried lignite typically contains about 60-75% carbon, 6.0-5.8% hydrogen, 17-34% oxygen, 0.5-3% sulfur and 1-1, 2% nitrogen.

In the conventional combustion of lignite for the production of energy, eg electricity, arise as combustion gases, especially C0 ₂ , S0 _{2 and} NO _x . The latter two gases are very harmful to the environment and must be removed from the exhaust of lignite power plants.

The object of the invention was to convert lignite into substances that can be burned in simpler, cheaper and less prone to failure facilities than in

conventional brown coal incinerators.

Summary of the Invention The invention relates to a process for recovering carbon and combustibles

Humid lignite or dry lignite gases humidified at the beginning of the process by continuously feeding the lignite from top to bottom in the direction of gravity into four zones in a moving bed in a suitable reactor permeate: a first zone or drying zone in which the moist or humidified lignite is dried by rising hot vapors and gases, a second zone or pyrolysis zone in which the dried lignite has a strong, preferably at least 98%, stoichiometric excess of oxygen pyrolyzed under evolution of pyrolysis gas, a third zone or zone of flame and a fourth zone or Glimmzone, which together form a Glutzone, in the remaining organic and metal-containing compounds at substantially stoichiometric oxygen supply, based on the organic and metal-containing compounds, oxidized and / or be burned / gasified, the unburned residue in the

Essentially pure, at least about 90% carbon comprises, which is continuously removed.

BRIEF DESCRIPTION OF THE DRAWING Fig. 1 shows a suitable one for carrying out the method according to the invention

Conversion device.

Fig. 2 shows a suitable for carrying out the method according to the invention

Reactor battery.

FIG. 3 shows a further reactor battery suitable for carrying out the process according to the invention.

Detailed description

It was surprisingly found that brown coal advantageous in one

In a moving bed continuously into a carbon concentrate (such as charcoal), ash and pyrolysis gas, which are thermally and electrically easy to recycle, can be converted.

The method is based on wet lignite or dry lignite, e.g. in the form of lignite briquettes, which before the start of the procedure by means of a

Moistening device is moistened to a water content of about 30%, continuously from top to bottom in the direction of gravity four zones in one

Walk through moving bed in a suitable reactor: a first zone

(Drying zone) in which the wet or humidified brown coal is dried by rising hot vapors and gases, a second zone (pyrolysis zone) in which the dried lignite with a high stoichiometric deficit (e.g.

at least 98% or at least 99% or even higher deficiency) of oxygen or preferably substantially free of oxygen with evolution of

Pyrolysis gas is pyrolyzed, a third zone (flame zone) and a fourth zone

(Glimmzone) (together: Glutzone), in the remaining organic and metal-containing compounds at substantially stoichiometric oxygen supply, based on the organic and metal-containing compounds, oxidized and / or burned / gasified, wherein the unburned residue is substantially pure carbon (at least about 90%, eg, at least about 95% carbon, depending on the purity of the lignite), which is continuously removed.

"Substantially oxygen-free" means that 0.5% by volume or less of oxygen is contained in the gas atmosphere.

"Substantially stoichiometric oxygenation based on the organic and metal-containing compounds" means that no more than about 5% by weight of these compounds, based on the product of charring, i. the

Carbon Concentrate in which the latter remain and that the gas which rises from the Glutzone not more than about 2 vol .-%, preferably not more than about 1 vol .-% and particularly preferably not more than about 0.5 vol .-% oxygen.

In the drying zone and in the pyrolysis zone, by rising hot vapors and gases, a temperature of about 450 ° C to about 900 ° C, preferably from about 500 ° C to about 550 ° C. The temperature of lignite residues in the flame zone is less than 600 ° C, while the flames have the usual flame temperature of more than 1000 ° C. The glow zone has a temperature of about 500 ° C to about 600 ° C, which is slightly below the combustion temperature of carbon on. With lignite having a variable water content, the temperature in the drying and pyrolysis zone can be controlled by controlling the air supply to maintain the required pyrolysis temperature. The moist or humidified brown coal in the drying zone also serves as adsorbent for longer-chain hydrocarbons and any sulfur-containing gases that are generated in the underlying pyrolysis zone and evaporate upwards. As the lignite migrates down into the pyrolysis zone, the longer-chain hydrocarbons are then further pyroylzed.

In the pyrolysis zone, organic compounds which may also contain nitrogen and sulfur as well as metals are pyrolyzed in the practical absence of oxygen. This produces a pyrolysis gas which is mainly carbon monoxide (CO), carbon dioxide (C0 ₂ ), nitrogen (N ₂ ), methane (CH ₄ ), hydrogen (H ₂ ), short-chain hydrocarbons and optionally sulfur-containing gases, such as H ₂ S, COS, CS ₂ , contains.

Very stable organic compounds, such as highly condensed aromatics, are burned in the flame zone and glow region (incandescent zone) to C0 _2, H ₂ 0 and, optionally, S0 ₂ or charred and metals are at least partially oxidized.

If sulfur-containing gases such as H ₂ S, COS and / or CS _{2 are formed} in appreciable quantities, they can be removed in a conventional manner, for example by means of desulfurization filters, from the gas leaving the reactor. Possibly contained S0 ₂ can also be removed by conventional methods, eg by lime washing.

There is no fly ash in this process.

The carbon formed and the pyrolysis gas containing CO, H ₂ , methane and short-chain hydrocarbons can be utilized thermally and electrically. Installations for the combustion of these products are much simpler, cheaper and less disruptive than plants for burning the raw lignite. DE 10 2005 038 135 B3 discloses an apparatus and a method for

continuous production of charcoal in a moving bed of wood or other biomass described. WO 2010/124761 discloses a further development of the device and the method.

In particular, the devices disclosed in WO 2010/124761 and in PCT / EP2010 / 007964 can be advantageously used for the process of converting charcoal into ash, pure carbon and pyrolysis gas. Fig. 1 shows such a conversion device 100, which is for continuous

Conversion of brown coal 102 is suitable, with a vertical

Supply area 104 and a wall 108 which define an interior space 106, and a grid forming a bottom 1 10 and one on a lid 1 12 of the

Feeding area 104 arranged rotary valve 1 16. The rotary valve 1 16 allows for the environment substantially gas-tight loading of the interior 106th Further, a gas outlet 1 18 is disposed on the lid 1 12, which is in communication with the interior 106 in the supply area 104. Under the grate 110, a downwardly tapering funnel 120 is connected with its funnel wall 122 with the interior 106. Through the funnel wall 122, an air supply 134, e.g. in the form of a pipe. At the lower narrow end of the hopper 120, a further downwardly leading pipe section 130 is connected. The pipe section 130 opens into another

Rotary valve 136, which serves as a discharge device. Supports 138, two of which are visible in Fig. 1, support the conversion device 100. The entire

Conversion device 100 or at least the wall 108 and the lid or are thermally insulated. The insulation reduces or prevents the condensation of gases generated in the interior space 106 on the inside of the wall 108.

The conversion device 100 may further be followed by a fluid distribution device. Also, the fluid distribution device may be integrally formed in the conversion device. There are exemplary embodiments in which the fluid distribution device has a mixing device arranged in a mixing device and a

Moistening device comprises. For example, the mixing device as a mixer or scrambled eggs. The mixer can be arranged below the reactor space in a mixing chamber.

By the rotary valve 1 16 lignite 102 passes continuously or

Batchwise into the interior 106. When starting the device is about 3/4 filled with brown coal 102, which is then ignited. In retracted operation, the interior 106 has four zones: a first upper zone (drying zone) 140 in

Supply area 104, in which the brown coal 102 is dried by rising warm vapors and gases 144 in the supply area 104. Below the upper portion 140 is a second zone (pyrolysis zone) 142, in which the dry brown coal is pyrolyzed with a large deficit or practical absence of oxygen to form pyrolysis gas. The adjoining third zone 144 is a flame zone in which remaining organic compounds burn at the air flowing from below through the air supply 134. Below the flame zone 142 is a lowermost zone 146, which is a glow zone in which the temperature is regulated by incoming air through the controlled air supply 134 to a temperature of 500-600 ° C and in which the last organic products present in the lignite are carbon, leaving essentially carbon or a carbon concentrate 158, which is so friable that it falls through the grid 1 10.

The carbon 158 falls through the pressure of the overlying and continuously advancing brewing coal 102 as well as by gravity due to the grid 110 therethrough. Openings of the grate 1 10 are made adjustable, so that the coal size or the flow rate of the charcoal 102 and the carbon 158 is controlled by the size of the openings. The carbon 158 falls due to gravity through the hopper 120, and the pipe section 130 in the other rotary valve 136, which discharges the carbon 158.

If the further cellular wheel lock 136 carries the carbon 158 into the fluid distribution device, then the carbon 158 can be sprayed / moistened and mixed with water by means of spray nozzles arranged in the walls or in the ceiling of the mixing chamber. Thus, the fluid distribution device may allow a defined supply of water into the carbon 158, so that less any evaporating water, a desired suitable water content of, for example, 15 to 25%, in particular from 18 to 20%, can be achieved in the carbon concentrate.

The air supply 134 in the pipeline 130 shown in FIG. 1 controls the supply of air or oxygen into the interior space 106. The convection-generated gas flow upwards in the supply area 104 draws ambient air through the opened air supply 134 and through the pipeline 130 and Funnel 120 up in the

Interior 160 drawn. If the gas outlet 118 is provided with a fan or the like, the pressure conditions in the upper region of the inner space 106 by the speed of the

Fan controlled. In this case, a pressure measurement takes place in

Interior space 106, preferably in the upper region close to the rotary valve 116 via a correspondingly suitable sensor device which generates a control signal. Depending on the control signal and thus the measured pressure, such as a negative pressure, the speed or speed of the fan and thus the after

externally derived exhaust gas quantity are controlled. Only through this speed control, the entire Verschwelungsprozess can be controlled. Pyrolysis gas 144 exits through the gas outlet 118 and is recycled.

Further suitable devices for the production of carbon from lignite are disclosed in copending PCT / EP2010 / 007964 and shown in Figures 2 and 3. Fig. 2 shows a reactor battery 200 for the continuous conversion of lignite. The reactor battery 200 here comprises seven by six individual reactors, hereinafter referred to as cells 202, which are arranged in a cuboid. The reactor battery is surrounded by a common reactor outer wall 204. For separating the individual cells 202 from each other, six transverse and five longitudinal dividing walls 206 extend within the outer walls 204 of the reactor.

All cells 202 are supplied with lignite continuously, as schematically indicated by the arrow 208 in FIG. Lignite from a brown coal storage is about to pipes a rotary valve (not shown) and from there via distribution pipes (not shown) to the individual cells passed. In a teilpyrolytischen conversion arise in the cells in addition to non-combustible and flammable gases with high calorific value, such as methane, carbon monoxide and hydrogen, and solid conversion product, namely carbon. The gases are removed at the top of each cell, as indicated schematically by arrow 210 in FIG. 2, and are collected via pipes (not shown), compressed and stored or else used thermally (combustion). The solid conversion product directs headers 212 below each cell, if necessary

gastight in a collecting container (not shown).

The reactor outer wall 204 is thermally insulated with rockwool or other suitable insulating material. Within the reactor battery wall, heat exchange takes place through the transverse and partition walls 206. The cells 202, however, remain materially isolated from each other. This causes lower heat losses compared to thermally decoupled cells. Each cell 202 is provided with a controllable / adjustable air supply

FIG. 3 shows a reactor battery 300 according to the invention which, like the reactor battery 200 shown in FIG. 2, comprises a plurality of reactors, which are referred to below as cells 302. In contrast to the cells 202 in FIG. 2, the cells 302 are each provided with their own cell wall 304a, 304b. Between cell walls 304b of juxtaposed cells 302, a schematic distance is visible in Fig. 2, but in fact does not have to be present. The cells are as close to each other as possible to allow good heat exchange between the cells 302. In the reactor battery 300 external cells are at their outer

Cells walls 304a thermally insulated, 304b not on their inner cell walls. A honeycomb honeycomb structure can improve the thermal properties (smaller outer surface). In the cells shown in Fig. 3, two conversion regions are distinguishable. In a lower region, the flame region 306, which comprises a flame zone and a glowing zone, lignite is charred in the case of substoichiometric oxygen supply to carbon. The resulting hot gases rise up the supply area 308th Die hot gases even contain little or no oxygen, since this is almost used up during charring. In the supply area, these hot gases cause drying, degassing and pyrolytic or partially pyrolytic conversion of lignite to combustible gases at temperatures of 500 to 900 ° C. This gas essentially comprises hydrogen, carbon monoxide, methane, short-chain hydrocarbons, carbon dioxide, nitrogen and possibly sulfur-containing gases which are removed.

In the drying of humidified brown coal resulting water vapor, the pyrolysis "shifts" slightly towards a gasification, whereby more combustible gas can arise. However, if too much water contained in the lignite, the heat required to dry the lignite can lower the temperature below the temperature necessary for pyrolysis. The dehumidification or drying can be controlled by controlling the air supply, so that the process for lignite with variable

Water content is adjustable.

The control of the pyrolysis is carried out by regular, controllable or adjustable air supply lines (arrows 310) or gas outlets in each cell. The cell walls 304b thereby prevent uncontrolled combustion channels 212 between the cells 302. If the cells 302 of the reactor battery 300 were combined into a single large combustion chamber, air from the air supply 310 of one cell and air from an adjacent air supply 310 could flow to a location in that large combustion chamber and form local combustion channels 312 in which lignite would burn completely, essentially producing only combustible and non-combustible gases but no more carbon and disrupting the process. Controlled partial pyrolytic decomposition would not be possible.

In general, a grid 314 supports the reaction material, ie the lignite. Below the grid 314, air is supplied through a feeder tube 310, for example, centrally to a respective single cell 302. The amount of air is precisely controlled and z. B. regulated by the temperature of an exhaust stream. Directly above the grating 314, under the conditions of relative lack of oxygen, charring of the brown coal or charring thereof occurs with substoichiometric oxygen supply. The relative lack of oxygen due to throttled air supply leads to combustion (or Partial combustion) of the volatiles of the reaction material while the solid carbon in the form of carbon concentrate falls down through the grid 314 out of the cell. The heat generated in this conflagration fire leads to the expansion of the resulting combustion gases, so that they are driven upwards in the reactor. About 0.5 to 0.8 m above the grating 314, the oxygen is consumed by the Verschwelungsprozess. Below this range is thus the oxygen zone, above begins the pyrolysis zone.

The now largely oxygen-free reaction gas, which mainly contains nitrogen and C0 ₂ , leaves the oxygen zone upwards at a temperature of about 500 to 600 ° C. Brown coal, which reaches this area on their way from above contains virtually no more water. It is heated under these conditions and gas is expelled pyrolytically. This rises further up and can be led out of the cell 302 led into a cogeneration plant or the like and the

Energy generation or used as district heating.

The conversion device 100 and the cells 302 can be designed as containers or in container form, for example as overseas freight containers. Several such containers can form a container battery. The containers are easily transportable by conventional means and can be assembled on site to form a container battery. The containers can be erected upright or transversely and connected to one another via a suitably suitable connecting means or connection, for example a framework, a flu, T-beam, screws, welded joints, etc.

Overseas containers are typically sea freight containers and ISO containers designed with 20- and 40-foot length and 8-foot width. Such overseas containers are not only ideal for transport on container ships, but also for transport by truck or rail.

Conversion devices in container form these easily accessible hard coal deposits can be transported, for example, in China, Russia or Canada. Also, the operation, replacement and maintenance of such Complete system of a conversion device in container form is easier.

Claims

claims

1. A process for the recovery of carbon and combustible gases from wet brown coal or dry brown coal, which is humidified at the beginning of the process by allowing the lignite to travel continuously from top to bottom in the direction of gravity through four zones in a moving bed in a suitable reactor: a first zone or drying zone in which moist or humidified lignite is dried by rising hot vapors and gases, a second zone or zone

Pyrolysis zone in which the dried lignite with a strong, preferably at least about 98% stoichiometric deficit of oxygen with evolution of

Pyrolysis gas is pyrolyzed, a third zone or flame zone and a fourth zone or Glimmzone, which together form a Glutzone, in the remaining organic and metal-containing compounds at substantially stoichiometric oxygen supply, based on the organic and metal-containing compounds, oxidized and / or burned / gasified wherein the unburned residue comprises substantially pure, at least about 90% carbon which is continuously removed.

2. The method according to claim 1, characterized in that the temperature in the drying zone and in the pyrolysis zone about 450 to about 900 ° C, preferably about 500 to about 550 ° C and that the temperature in the Glutzone about 500 to about 600 ° C is.

3. The method according to claim 1 or 2, characterized in that the

Oxygen supply depending on the amount of water in the lignite is controlled so that the temperature in the drying zone and pyrolysis zone at about 450 to about 900 ° C, preferably about 500 to about 550 ° C aufrecherhalten.

4. The method according to any one of claims 1 to 3, characterized in that the gas emerging from the reactor and pyrolysis gas optionally after

Desulfurization essentially contains CO, H ₂ , methane, short-chain hydrocarbons, N ₂ , and C0 ₂ .