JP2018002793A - Gasification of wood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method capable of largely gasifying also a woody component generated by the uncombustion upon gasification of a wood.SOLUTION: Provided is a device where the material to be gasified is fed to the upper region of a gasifier 1, oxygen in the form of air is fed to the central region, and gasification is performed in the stationary reactor of the lower region in which a production gas is draw out from the lowermost region of the gasifier 1 via a product gas line 6 and is introduced into the lower region of a high temperature gas filter 2, solid matters such as grains, ash and foreign matters are separated at a filter cartridge 7, a pure gas is exhausted via a pure gas line 8, and the bottom part region of the high temperature filter 2 is provided with a discharge part 10 for exhausting the remaining solid matters. Oxygen in the form of air is fed to a space between the filter bottom part 13 of the high temperature gas filter 2 and the discharge part 10 via a line 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus and method for gasifying wood or other carbon-containing materials corresponding to the superordinate concept of claim 1 and the superordinate concept of claim 3 and WO 95/24591 (Patent Document 1).

  This document discloses a fluidized bed for a combined cycle power plant where it is provided that the reactor has a secondary air supply and a tertiary air supply that opens at different heights within the reactor. ing.

  US Patent Application Publication No. 2008/0127824 A1 discloses a regeneration filter for a coal gasification plant in which unburned material is combusted by the supply of oxygen performed using a nitrogen-air mixture. ing.

  Analogously, US Pat. No. 6,077,490 (Patent Document 3) contemplates the use of two filter cartridges.

In contrast to the prior art, in general:
Wood is chemically composed of three main components:
-Cellulose-hemicellulose-lignin-balance

Cellulose The main component of all woody plants is composed of about 50% cellulose. Cellulose is a chain-structured molecule composed of several glucose units. The original components of cellulose are cellobiose and disaccharides.

Hemicellulose Hemicellulose is composed of high molecular carbohydrates, and its constituent components are composed of pentose and hexose. Hemicellulose is a polysaccharide similar to cellulose.

Lignin The third component of wood is lignin, which is a polymer consisting of about 25-30% phenylpropane units based on its mass.

The balance In addition to cellulose, hemicellulose, and lignin, there are fats, resins, terpenes, pigments and tannins, and mineral components in the wood.

Elemental composition Woody molecular formula:
C _6.1 H ₉ O _4.2 (1.2)
Comparison household sugar:
C ₁₂ H ₂₂ O ₁₁ (2.2)

Thermo-chemical conversion Through a thermo-chemical finishing process (gasification), a solid bioenergy source is converted in a first line into a gaseous second energy source under heat flow. During gasification, biomass is converted to combustible gas (ie, so-called synthesis gas) as completely as possible at high temperatures. To that end, less than an equivalent oxygen-containing gasifying agent (air) is supplied to the process, thereby converting the carbon contained in the biomass into carbon monoxide. At the same time, the gasification process can take place at any time (autothermal gasification) because the necessary process heat is provided by partial combustion of the input material. The generated low calorie gas is used to supply heat to the banner and to generate a fluid flow in the engine or gas turbine.

DC fixed bed gasification In this type of gasification, solid particles (wood) do not move with the gas flow. The fuel travels through a carburetor in the form of a floor. The gasification residue is received in the lower region of the carburetor. Fuel and gas follow the same path.

Heating and drying The first phase is characterized in that the wood is slowly heated from outside to inside. The liberated water is sent in the form of water vapor. This process is endothermic (requires energy).

Degassing and thermal decomposition (Pyrolyse)
The temperature in the pyrolysis phase or pyrolysis zone moves from 200 ° C to 400 ° C. At this temperature, oxygen (O2) and hydrogen (H2) are degassed. As mentioned in the previous chapter, the woody components are gasified in this phase. During pyrolysis, cellulose and hemicellulose produce carbon dioxide (CO2) and carbon monoxide (CO) as well as acetic acid (CH3COOH), acetone (C3H6O), phenol (C6H5OH) and water (H2O). The long-chain hydrocarbon generated during the thermal decomposition is called tar.

  During pyrolysis of lignin, methanol (CH3OH) and aromatic hydrocarbons (eg, benzene (C6H6)) are produced.

  Charcoal is produced as the pyrolysis solid.

The energy required for oxidative drying, pyrolysis and reduction is formed in this zone. Carbon and hydrogen burn with energy supply (endothermic). In this zone, the temperature moves from 650 ° C. to 1100 ° C., and CO ₂ , H ₂ O and CH ₄ are produced (see below, unsigned).

Reduction In the reduction zone, combustion gas can be generated. In this case, the original gasification of solid carbon occurs. In this reduction zone, CO2 and H2O, which are intermediate products generated by the oxidation in the previous process, are reduced to charcoal that burns red. At that time, CO, H 2 and higher hydrocarbons are generated. This is done at about 1100-650 ° C.

  The reduction proceeds depending on the prevailing temperature. At that time, the conversion of hydrogen and carbon to methane rapidly decreases between 400 ° C and 600 ° C. At temperatures above 1000 ° C., methane is no longer formed. The Boudouard reaction is achieved at high temperatures and good yields of carbon monoxide are obtained. This reaction proceeds relatively slowly.

  There is a tendency opposite to temperature dependence between the production of CO and the production of higher hydrocarbons. Furthermore, the production of hydrogen recedes due to methane formation. Two ingredients increase the value of heat. High hydrogen content increases engine knock problems. Anti-knock methane is a good fuel gas, but for the production of gas resulting from a high methane content, the gas has a high content of tar.

Process of the gasification process First, the wood is heated by the heat supply, and at this time, the water present in the gasification material evaporates. The amount of heat required is generated by the partial combustion of the carbonized gas and the oxidation of carbon and hydrogen.

  The charcoal thus obtained is used as a reaction surface for the oxidation and reduction of carbon, carbon monoxide, carbon dioxide and water. Here, the reaction rate is increased by reducing the charcoal, that is, by increasing the surface area of the particles.

  Here, when the reaction zone is viewed as a whole, it is clear that the reduction and oxidation must proceed simultaneously. Since the reduction of carbon dioxide by charcoal is endothermic, the temperature decreases from the bottom to the top, thereby gradually quenching the reaction. There is no clear boundary between the reduction zone and the oxidation zone.

In the oxidation zone, it is presumed that it becomes CO ₂ by combustion of carbon. This is because the dominant high temperature of 1000-1300 ° C. in the zone no longer provides CO ₂ tolerance.

Thereafter, a portion of the carbon monoxide should be CO ₂ in the combustion in the presence of oxygen. However, it is not stable at high temperatures and is reduced to CO in red burning carbon. When the oxygen is completely exhausted, the CO does not burn any more and remains stable in that concentration despite the temperature becoming lower. However, if one considers it after all, it must be taken into account that CO ₂ is initially present, so that in this case too, it must be started from the reduction reaction.

  As is evident from the above process, by gasification of the mixture from flammable and non-flammable gases, the mixture is decomposed as follows:

1. Flammable gas:
・ Carbon monoxide CO
・ Hydrogen H ₂
・ Methane CH ₄
・ High molecular weight hydrocarbon compounds

2. Incombustible gas:
・ Carbon dioxide CO ₂
・ Nitrogen N ₂
・ Water vapor H ₂ O
・ A small amount of oxygen O ₂

  Process performance, residence time, temperature and fuel type, particle size and humidity affect the composition of the woody gas. Typically, the amount of heating for wood is on the scale of 3.5 to 5.5 MJ / m3, so the wood gas is lean gas.

International Publication No. 95/24591 Pamphlet

  5-10% by weight of the starting material is present as wood residue, which is mainly ash, but not gasified, and must be disposed of properly, which is economically and ecologically relevant. This means that the wood component generated by unburned wood gasification according to the prior art should be gasified as much as possible. This is also the subject of the present invention.

  The present invention solves this problem by a device having the features indicated in the characterizing part of claim 1 and a method having the features indicated in the characterizing part of claim 3. In other words: charcoal, which is incidentally produced without being gasified in the bottom region of the gas generator, is transferred at least in large part to a hot gas filter provided downstream by a gas fluid stream. This can be accomplished by appropriately selecting the fluid flow rate by means of pneumatic transport techniques, as in the more well-known bulk transport. In a hot gas filter, charcoal, and coal dust and accompanying ash are separated on the surface of the filter, which is preferably a filter cartridge. Depending on the pressure loss in the filter, oxygen (usually in the form of air) is introduced into the filter cartridge as violently as possible upstream, so that the filter cake breaks and scatters in the filter cartridge, It then favors pressure rise and temperature, and a second gasification step is performed, whereby a much overwhelming part of the resulting charcoal or pulverized coal is gasified. The part that is not yet gasified is finally gasified by oxygen supplied to the lower part of the filter—again, preferably in the form of air. Depending on the process parameters, which are easy to determine the structure of the device and the operation of the device when unknown in advance, the wood gasification to mineral ash can be carried out essentially completely.

FIG. 1 schematically shows the device of the present invention.

  In the drawing consisting of only one figure, the device according to the invention is represented schematically only. In that case, components that are not causal in context with the present invention are omitted from the components in the figure. In particular, the upstream and downstream components of equipment such as numerous instruments, control and shut-off equipment, steering gear, user bearings, drying means, final product gas purification and conversion are Those skilled in the field of equipment are well-known and no further description is necessary in connection with the present invention.

  The device of the present invention is schematically illustrated in this single view-even in the absence of the elements and components essential to the present invention--such as instruments. These essentially have: a gasifier 1 and a hot gas filter 2. Wood chips, wood pellets, coal, etc. are appropriately supplied from the head to the gasifier 1 via a supply 3 from a storage bunker not shown and are described at the beginning in those known from the prior art. In addition, through the steps of drying, swelling, oxidation and reduction, air is appropriately supplied through the line and distributor 5 in the lower region indicated by reference numeral 4. A typical wood gasifier has a fixed bed that is driven by a homogeneous fluid flow. In its lower region, reduction takes place after oxidation and unburned parts and ash are withdrawn together with the product gas in the bottom region of the gasifier via line 6 and introduced into the central region of the hot gas filter 2 Is done.

  In this lower region of the hot gas filter 2, the filter cartridge 7 projects downward from the filter bottom 13. Although filter cartridges are not essential for continuous operation, even if they are sufficient under certain circumstances, it is advantageous to provide at least two such filter cartridges 7. Through the filter cartridge, the product gas passes and collects and reaches into the upper region of the hot gas filter 2, where a product called pure gas is withdrawn via the pure gas line 8 and is further processed or Supplied for use.

  The filter cartridges 7 are adjustably connected to a pressurized air supply 9, which is used to set intermittently on their pure gas surfaces under overpressure using the pressurized air supply. It is possible to separate and at least partially gasify the filter cases accumulated on these crude gas surfaces. In the lower region of the high-temperature gas filter 2, a take-out part 10 for the components not gasified and a corresponding ash container 11 are provided.

  In accordance with the present invention, now heated oxygen and / or dried oxygen, for example in the form of air, is sent via line 12 to the lower half area of the filter bottom 13 (for example the lower end of the filter cartridge). As a result, in the crude gas region of the hot gas filter 2 a very complete gasification of the wood components which have not yet been gasified proceeds further.

  Thus, the still non-gasified part of the wood can be reduced to essentially mineral ash, which is very noteworthy both for the environment and for economic reasons. In effect, in the prior art, 5-10% by weight of the input fuel cannot be gasified, and therefore proper waste disposal is necessary; The yield of 90% to 95% is increased to 99% by the present invention in addition to 10% to 20% of the waste generated so far. Reduced to! In contrast, the negligible excess costs for enhancing the transport to line 6 and the costs for blowing the reaction air into the hot gas filter 2 via line 12 are also critically important. Absent.

  The present invention is not limited to the illustrated embodiment, and various modifications are possible. Thus, for large equipment, several gasifiers and / or several hot gas filters can be appropriately combined with one another so that continuous operation can be achieved even in the case of maintenance. Depending on the nature of the starting material and the possibility of feedback to the product stream, to the gasifier for wood components that are too heavy even in the increased line, to the gasifier for such parts later It is possible to provide a discharge device that can be fed back or discarded.

  The present invention allows the method or apparatus of the present invention to be combined with different alternatives, so long as the reaction is not hindered in the hot gas filter or is not disturbed by other embodiments of the filter process.

  By performing the second gasification step with a hot gas filter, the state conditions therein are not essentially changed as required to change or adapt the material, so that In the case of a gas filter, all parts and materials envisioned by those skilled in the art can be used.

  The height at which the nozzle or other opening of the supply line 12 enters the hot gas filter 2 is appropriate at the lower end when the filter cartridge 7 is present. There, when the filter cake breaks and scatters, all the material collects, as well as during the operation without problems, as well as the material that is not yet gasified. Operating parameters such as overpressure and volume flow are easily determined by several experiments. If different materials are gasified and it is advantageous under certain circumstances, nozzles are provided at various heights that can be supplied individually or in groups.

  Also, by arranging the nozzles diagonally, a special fluid flow pattern is obtained, thereby further gasification.

  In summary, the present invention is an apparatus for gasifying a hydrocarbon-containing material, in particular wood, by means of the gasifier 1, which is supplied with the material to be gasified in its upper region, and Oxygen, usually in the form of air, is supplied to the central region of the gasifier, and in the lower region of the gasifier, most of the material is gasified in a fixed bed, with the gasification Product gas is withdrawn from the lower region of the vessel 1 via the product gas line 6 and introduced into the lower region of the hot gas filter 2, where it is preferably fed via a filter with a filter cartridge 7. Solids such as ungasified particles, ash and foreign matter are separated, while pure gas arrives there and is transported via the pure gas line 8, where the high temperature Gas filter To eliminate solids remaining in the second base region, which was taken out portion 10 is provided, and said. At that time, the hot gas filter 2 is supplied with oxygen, preferably in the form of air, via the line 12 between the filter bottom 13 and the take-out part 10 in the central height region.

  The invention also relates to a method for gasifying a hydrocarbon-containing material, in particular wood, by means of a gasifier 1 and a hot gas filter 2 downstream in the product stream, in which the front of the filter in the product stream. In addition, the hot gas filter 2 is supplied with oxygen, preferably in the form of air, so that further gasification processes are carried out.

  The term “major” in relation to a material means more than 50% by weight, preferably more than 80% by weight, particularly preferably more than 95% by weight; a reactor, filter, structure or device, or more generally The “lower area” of the object means the lower half of the overall height, especially the lower quarter, and the term “bottom area” is the lower quarter, especially smaller. Means the part; and the term “central region” means the middle third of the total height. All of these indicators are also commonly used to mean “top”, “bottom”, “front”, “back”, etc. and apply to objects observed at their intended location. It should be noted that.

  The term “essentially” is used herein and in the claims to be a 10% deviation from a given value, where physically possible, and that both downward and upward are Yes, only in the other case is it separated by a meaningful direction.

01 Carburetor 02 Hot air filter 03 Feeder 04 Mounting part 05 Distributor 06 Product line 07 Filter cartridge 08 Pure gas line 09 Pressurized air supply 10 Extraction part 11 Ash container 12 Supply line 13 Filter bottom part

Claims (3)

A device comprising a gasifier (1) for gasifying carbon-containing materials, in particular wood, where the material gasifying into the upper region of the gasifier and in its central region, mostly A device in which oxygen is supplied in the form of air and in the lower region is mostly gasified in a fixed bed reactor, with the production from the lowermost region of the gasifier (1) The product gas is withdrawn via the product gas line (6) and introduced into the lower region of the hot gas filter (2), which is preferably fed via a filter with a filter cartridge (7), Solids such as particles, ash and foreign matter that have not been gasified are separated, while clean gas passes through it and is discharged through the clean gas line (8), with the remaining solids The hot gas to discharge Filter pickup section in the bottom region of (2) (10) are provided, a said device,
In the middle height region of the filter between the filter bottom (13) of the hot gas filter (2) and the extraction part (10), oxygen is preferably introduced in the form of air via a line (12). A device as described above, characterized in that it is supplied.   Movement (Zug) in the product line (6) essentially causes particles that have not been gasified in the gasifier, for example by a blower, to move together with the hot gas filter (2). The device according to claim 1, wherein the device is strengthened.   A method for gasifying a carbon-containing material, in particular wood, using a gasifier (1) and a high-temperature gas filter (2) downstream of the product stream, wherein the high-temperature gas filter in the product stream before the filter Process as described above, characterized in that (2) is supplied with oxygen, preferably in the form of air, and thereby undergoes a further gasification process.

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