DE102009060733A1 - Apparatus for continuous conversion of biomass and energy generation system therefrom - Google Patents

Abstract

The invention relates to a reactor battery (100; 200) for the continuous conversion of biomass, with several cells (102; 202), each of which has a feed area (208) for drying, degassing and converting the biomass to a combustible gas and a flame area (206) for converting the biomass to a solid conversion product, the conversion taking place pyrolytically in the feed area of each cell (102; 202).

Description

The present invention relates to a reactor battery for the continuous conversion of biomass and a system for generating energy from biomass.

The DE 10 2005 038 135 B3 discloses an apparatus for the continuous production of charcoal in a moving bed of wood or other biomass. The apparatus comprises a wood or other biomass feed device, a well in which the moving or wood biomass bed is dried, degassed and charred, one or more air supply means located in the lower part of the well and one in the lower part of the well grating. The charcoal passing through the grate is collected below it in a water basin, cooled, conveyed out of the water basin and must be dried before further use.

The FR 2 677 661 describes a plant for the carbonization of wood to coal without smoke emission. The coal is automatically discharged from the plant after carbonation. For carbonization several separate stoves are used. The floors of the ovens are inclined to a bottom flap. When these bottom flaps are opened, a batch of charcoal from the ovens may slip into a common container. The air supply of the individual ovens leads to several places in the ovens and is controlled by closing mechanisms. Carbonisation produces smoke in a chimney.

The EP 1535982 A1 describes a device with a combustion chamber for the batch production of charcoal. For the device, a controllable ventilation opening is provided which directs air through a two-pipe system in the upper region of the combustion chamber. In the combustion chamber resulting smoke is dissipated in the lower part of the combustion chamber and blown out through a fireplace. EP 1535 982 A1 also describes the use of a grid in the bottom of the combustion chamber, as well as several openings in the ground. This arrangement serves to provide and burn off an additional fuel which treats the raw material to be processed in the combustion chamber in a high temperature refining step.

The object of the present invention is to provide an energy-efficient and simple device for the continuous conversion of biomass and a system for obtaining energy from biomass.

According to the invention, this object is achieved by the subject matter of the independent claims. Variants and preferred embodiments of the invention will become apparent from the claims, the following description and the drawings.

The reactor battery according to claim 1 for the continuous conversion of biomass comprises a plurality of cells each having a supply area for drying, degassing and converting (a part of) the biomass to a combustible gas and a flame area for converting the biomass into a solid conversion product. In this case, the conversion takes place pyrolytically in the feed region of each cell.

The supply range of a cell takes z. As a moving bed of biomass, especially wood, and is divided into an upper section for drying, a middle section for degassing and for pyrolytic conversion of the biomass. A lower portion of the cell forms a flame zone for charring the biomass to a solid conversion product, especially charcoal. Under the flame area z. As a grid may be arranged, which supports the moving bed and which is permeable to the solid conversion product down.

Continuous conversion offers time advantages over batch or batch processes. In such processes, a portion of biomass is first fully processed before the next position can be processed. If necessary, the system must always be restarted. However, the device according to the invention enables a continuous operation; So also when supplying biomass and the discharge or removal of conversion products.

In the feed area, moist biomass is largely dehumidified or dried by charring hot gases upstream of the charring in the flame area. This increases the calorific value of the solid conversion product. The temperature in the feed area can be between 500-900 ° C. Such temperatures allow for largely oxygen-free conditions pyrolytic decomposition of biomass. Pyrolysis is generally the term for the thermal decomposition of organic compounds, whereby high temperatures (500-900 ° C) break up bonds within large molecules. Mostly, this happens under exclusion of oxygen (anaerobic) to prevent combustion. One speaks also of a Verschwelung.

Depending on the flow velocity of the biomass moving bed, the pyrolytic transformation is more or less complete (partial pyrolysis) instead of. With longer residence time more flammable gas is generated. With shorter residence time, more unconverted biomass reaches the flame area.

The arrangement of a plurality of cells, each carrying out the processes described above, in a reactor battery enables improved process control, in that the oxygen or air supply can each be adjusted to a relatively small range. Thus, pyrolysis or partial pyrolysis and charring can be reliably controlled for each cell. For larger undivided reactors, however, there may be unregulated, local chimney and combustion effects that hinder the desired teilpyrolytischen decomposition effect.

According to a development, the reactor comprises an adjustable air supply per cell. Preferably, the supply of air from below the grid is such that a desired amount of air enters the flame area of each cell. In the flame area, the biomass is charred at substoichiometric oxygen supply or relative lack of oxygen, z. B. to charcoal. At appropriate temperatures, partial combustion of volatiles of the biomass takes place while carbon (eg, charcoal) falls down through the grid.

The released waste heat increases the volume of the combustion gases, which are driven so convectively in the cell upwards and dry and degas the biomass in the feed area. The oxygen supplied via the air supply is almost completely consumed for decomposition in the flame region. The combustion gases driven upwards are thus substantially oxygen-free or oxygen-poor and thus create temperatures and conditions for a pyrolytic or partially pyrolytic conversion of the biomass in the feed region.

Conventional Karbonisierungsanlagen lead, in contrast, air or oxygen at several points in a combustion chamber so that in a large combustion chamber, a char is easily controllable, but due to the oxygen no simultaneous pyrolytic, d. H. essentially oxygen-free, conversion takes place.

According to a development, the reactor battery comprises a control device for measuring the temperature, in particular the exhaust gas temperature, in individual cells or in the collected exhaust gases in the reactor battery, and for controlling the amount of air supplied via the air supply.

If the temperature is measured in individual cells, this can serve as a manipulated variable for the control device in order to control the air supply to the individual cells in such a way that a desired temperature profile or a temperature profile over the supply region of each cell is maintained.

A reactor battery can also be partially started or stopped by cell-controlled air supply. In addition, a desired temperature gradient can be generated by cell-controlled air supply. For example, an elevated temperature may be required in the outer cells of the reactor battery to compensate for heat losses to the environment. In addition, conditions for higher gas production in some of the cells of the reactor battery and conditions for higher production of solid conversion products in another part of the cells can also be set.

There are embodiments in which the reactor battery comprises a central exhaust gas removal device. This includes manifolds that lead from upper portions of the individual cells to a collection tank and / or chimney. The temperature can be detected, for example, centrally to the collected exhaust gases to obtain a common control variable for the control device for controlling all air supplies.

According to a development, the reactor battery comprises a supply device for the continuous supply of biomass, in particular wood chips. The feeder has z. As a rotary valve on biomass largely under exclusion of gas continuously in the individual cells can promote. The supply device may also comprise distributor tubes which convey the biomass from a biomass store via the rotary feeder to the individual cells.

According to a development, the reactor battery comprises a discharge device per cell in order to discharge the solid conversion product. There are embodiments with headers, which lead starting from the areas of the reactor battery, which are below the grid of each cell, in a slight gradient to a gas-tight container in which the solid conversion product is taken up and cooled.

According to a development, the reactor battery is thermally insulated on its outer side. There are also embodiments in which the cells are designed in their structure or arrangement so that the reactor is a teilpyrolytische conversion of biomass into a solid conversion product and a combustible gas.

According to a development, the reactor battery is modular with individual reactor cells formed rectangular section. Such individual reactors can be assembled particularly simply by juxtaposing into a likewise cuboid reactor battery. A honeycomb structure is also possible. Such a modular design allows to add or remove individual cells. In this case, the cells of the reactor battery are single-walled and double-walled.

When a reactor battery is made by a common outer reactor wall and several intermediate or partition walls, the cells may be designed to be single-walled and single-walled. This variant is more material-saving.

A biomass energy production system comprises a reactor battery according to the invention, a combined heat and power plant for burning the combustible gas and a press for pelleting or briquetting the solid conversion product, in particular charcoal.

According to a development, the system also includes a kiln for burning the pressed conversion product. The kiln, the reactor battery and / or the pelleting or briquetting device may also be arranged separately from each other.

Such a system allows a high energy yield of the biomass with high spatial flexibility, since the resulting in the conversion of gases z. B. can be used locally in eifern cogeneration plant, while the solid conversion product by pelleting or briquetting is easily transportable and metered and in remote facilities z. B. can be used in households.

Hereinafter, further embodiments of the invention will be explained in more detail with reference to schematic drawings. Showing:

1 shows a schematic view of an embodiment of the reactor battery according to the invention

2 shows a partially broken side view of an embodiment of the reactor battery according to the invention

1 shows a reactor battery according to the invention 100 for the continuous conversion of woodchips. The reactor battery 100 here comprises seven times six individual reactors, hereinafter referred to as cells 102 referred to, which are arranged in cuboid. The reactor battery is from a common reactor outer wall 104 surround. To separate the individual cells 102 Six transverse and five longitudinal partitions run from each other 106 within the outer walls of the reactor 104 ,

All cells 102 are continuously supplied wood chips, as indicated by the arrow 108 in 1 indicated schematically. Woodchips from a woodchip storage are passed via pipes to a rotary valve (not shown) and from there via distribution pipes (not shown) to the individual cells.

In a teilpyrolytischen conversion arise in the cells in addition to non-combustible and combustible gases with high calorific value, z. As methane, carbon monoxide and hydrogen, and solid conversion products, for. B. charcoal. The gases are removed at the top of each cell as indicated by arrow 110 in 1 indicated schematically and are collected via pipes (not shown), compressed and stored or else used thermally (combustion). The solid conversion products conduct manifolds 112 below each cell if necessary gas-tight in a collecting container (not shown).

The reactor outer wall 104 is thermally insulated with rock wool or other suitable insulating material. Within the reactor battery wall heat exchange takes place through the transverse and partition walls 106 therethrough. The cells 102 however, remain materially isolated from each other. This causes lower heat losses compared to thermally decoupled cells. Every cell 102 is provided with a controllable / adjustable / adjustable air supply z. B. is controllable via a the exhaust gas temperature sensing control. The control can take place cell by cell (locally) or by reactor (globally). It is also possible to make a local manual or automatic presetting (eg marginal cells other than central cells) and then to perform a globally controlled air supply control during operation - albeit cell by cell.

2 shows a reactor battery according to the invention 200 like the ones in 1 shown reactor battery 100 includes several reactors, hereinafter referred to as cells 202 be designated. The cells 202 are unlike the cells 102 in 1 each with its own cell wall 204a . 204b fitted. Between cell walls 204b of juxtaposed cells 202 is in 2 a schematic distance visible, but in fact does not have to be present. The cells are as close together as possible to ensure good heat exchange between the cells 202 to be able to produce. In the reactor battery 200 External cells are on their outer cell walls 204a thermally insulated, on their internal cell walls 204b Not. A honeycomb structure can improve the thermal properties (lower outer surface).

In the in 2 2 cells are distinguishable. In a lower area, the flame area 206 , woodchips are charred to charcoal with substoichiometric oxygenation. The resulting hot gases rise up the supply area 208 , The hot gases themselves contain only little or no oxygen, as they are almost used up during charring. In the supply area, these hot gases at temperatures of 500 to 900 ° C cause drying, degassing and pyrolytic or teilpyrolytische conversion of wood chips to combustible gases. This so-called wood gas essentially comprises hydrogen, carbon monoxide, methane, carbon dioxide and nitrogen.

In the drying of biomass resulting water vapor "shifts" the pyrolysis slightly towards a gasification, whereby more combustible gas can arise. However, if too much water is contained in the biomass, the heat required to dry the biomass can lower the temperature below the temperature necessary for pyrolysis. The dehumidification or drying can be controlled via the control of the air supply, so that the process for differently composed biomasses (eg variable water content) is adjustable.

The air required for charring (with oxygen) in the flame area passes through regular, controllable or adjustable air supply, indicated schematically by the arrows 210 , in every cell. The cell walls 204b prevent uncontrolled combustion channels 212 between the cells 202 , Would the cells be 202 the reactor battery 200 combined into a single large combustion chamber, so could air from the air supply 210 a cell and air from an adjacent air supply 210 to a point in this large combustion chamber and to flow local combustion channels 212 form, in which wood chips would burn completely, whereby essentially only combustible and non-combustible gas but no charcoal would be generated, and the process would be disturbed. Controlled partial pyrolytic decomposition would not be possible.

In general, a grid will support 212 the reaction material, ie the biomass. Below the grid 212 is air through a z. B. feed pipe 210 approximately centrally of a respective single cell 202 fed. The amount of air is precisely controlled and z. B. regulated by the temperature of an exhaust stream. Directly above the grid 212 Under the conditions of relative lack of oxygen, carbonization of the biomass (wood, etc.) or charring thereof occurs with substoichiometric oxygen supply. The relative lack of oxygen due to throttled air supply leads to the combustion (or partial combustion) of the volatiles of the reaction material, while the solid carbon in the form of carbon concentrate down through the grid 212 falls 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 meters above the grid 212 is the oxygen consumed by the pollination process. Below this range is thus the oxygen zone, above begins the pyrolysis zone.

The now largely oxygen-free reaction gas, which contains mainly nitrogen and CO ₂ leaves the oxygen zone upwards at a temperature of about 500 to 600 ° C. Biomass, which reaches this area on its way from the top, contains virtually no water. It is heated under these conditions and wood gas is expelled pyrolytically. This continues to rise and can leave the cell 202 discharged discharged into a cogeneration plant or the like and used for energy or as district heating.

Other aspects and variations of the invention will become apparent to those skilled in the art from the appended claims.

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 102005038135 B3 [0002]
• FR 2677661 [0003]
• EP 1535982 A1 [0004]

Claims (10)

Reactor battery ( 100 ; 200 ) for the continuous conversion of biomass, comprising: a plurality of cells ( 102 ; 202 ), each having a supply area ( 208 ) for drying, degassing and converting the biomass into a combustible gas and a flame zone ( 206 ) for converting the biomass to a solid conversion product, wherein the conversion is pyrolytic in the feed region ( 208 ) of each cell ( 102 ; 202 ) he follows. Reactor battery ( 100 ; 200 ) according to claim 1, with an adjustable air supply ( 210 ) per cell ( 102 ; 202 ). Reactor battery ( 100 ; 200 ) according to claim 2, comprising a control device for measuring the temperature, in particular the temperature of gases in individual cells ( 102 ; 202 ) and / or in the reactor battery ( 100 ; 200 ), and for controlling the air supply ( 210 ) amount of air supplied. Reactor battery ( 100 ; 200 ) according to one of the preceding claims, with a supply device for the continuous supply of biomass, in particular wood chips. Reactor battery ( 100 ; 200 ) according to one of the preceding claims, with a discharge device ( 112 ) per cell ( 102 ; 202 ) to discharge the solid conversion product. Reactor battery ( 100 ; 200 ) according to claim 4, wherein the discharge device comprises collecting pipes ( 112 ) for collecting the solid conversion product. Reactor battery ( 100 ; 200 ) according to one of the preceding claims, which is thermally insulated to the outside and / or in which the cells ( 102 ; 202 ) are designed in their structure or arrangement such that they undergo a partial pyrolytic conversion of biomass into a solid conversion product and a combustible gas. Reactor battery ( 100 ; 200 ) according to one of the preceding claims, which is modularly composed of individual reactors ( 202 ) is constructed with a rectangular cross-section. System for generating energy from biomass, in particular wood, comprising: a reactor battery ( 100 ; 200 ) according to one of claims 1 to 8, a cogeneration plant for combusting the combustible gas and a press for pelleting or briquetting of the solid conversion product, in particular charcoal. A system according to claim 9, including a kiln for burning the solid, pressed conversion product.

Images