Device for generating a flammable gas mixture

Abstract

Device for generating a flammable gas mixture from a carbon-containing starting material, comprising a feed unit (2) for supplying the starting material to a reactor (1), wherein the reactor (1) comprises at least one oxidation zone (10) for oxidizing the starting material and a reduction zone (12) for reducing at least one intermediate product of the oxidation, wherein the feed unit (2) comprises at least one storage device (4, 34) for intermediate storage of the starting material, which has at least one opening (9, 39) for introducing the starting material, wherein the opening (9, 39) can be closed with a closing element (6, 36) which interacts with the sealing surfaces (7, 37) of a seal in the area of ​​a closing surface, characterized in that the feed unit (2) has at least one inlet lock arranged in the direction of movement of the starting material and comprising at least two gas-tight closing elements (6, 36),and that at least one closure element (6, 36) seals against a sealing surface (7, 37) of the seal which is oriented substantially in the direction of movement of the starting material and which is designed as a hollow cylinder, and that the closure element (6, 36) extends into the seal along the sealing surface (7, 37) and is pivotable about a rotation axis (5, 45) arranged outside the closure surface.

Description

[0001] The invention relates to a device for producing a flammable gas mixture from a carbon-containing starting material according to the preamble of claim 1. State of the art

[0002] European patent EP 1 436 364 B1 of the applicant discloses a device for generating a combustible gas mixture, in particular wood gas, preferably for an internal combustion engine, wherein a virtually tar-free wood gas can be generated by oxidation and subsequent reduction in the reactor. For this purpose, the reactor is fed laterally with wood chips via an intermediate storage tank and is equipped with a level sensor for detecting the fill level of the reactor.

[0003] Furthermore, the aforementioned publication already discloses a nearly gas-tight sealing element in front of the intermediate tank, which can be designed as a slide valve, a rotatable or pivoting flap, or the like. The embodiment with a pivoting flap was also illustrated in an exemplary drawing. However, since this flap has a pivot axis within the sealing element or the inlet opening, the problem arises that lumpy feedstock, such as wood chips, can become lodged on the sealing surface, specifically on the rotating plate of the shut-off valve, potentially blocking the subsequent closing action of the flap. A nearly gas-tight seal is then no longer achieved, which impairs the chemical reaction in the reactor and leads to a problematically high tar content in the synthesis gas.

[0004] On the other hand, the alternative valve design, using a slide valve, also presented the problem of leaks. In this case, they result from the accumulation of contaminants on the sealing surface. This problem is particularly pronounced in the device according to the invention for generating a combustible gas mixture, since intermediate products of gas production spread to a certain extent from the reactor into the storage device. Consequently, a gas atmosphere prevails at the valve that contains a tar content, even if only a very small one, which causes wood chip fragments, dust, or sawdust to be deposited more readily on surfaces, forming a sticky layer.

[0005] Devices for closing an opening in a vessel or conduit containing a dust-containing, flowable material are known in the prior art. For example, AT 005 651 U1 discloses a flap for closing an opening, wherein both the flap and the opening have a sealing surface, and wherein a device is provided for rinsing the sealing surface of the closure body and / or for rinsing the sealing surface of the opening to be closed. The rinsing device is arranged directly on the sealing surface of the closure body and / or directly on the sealing surface of the opening to be closed. It is thus a rinsing medium, such as a rinsing solution, with which the deposition of particles on the sealing surfaces is prevented.However, such a medium would impair the chemical reactions in the reactor / oxidation reactor, so such a device cannot be used in the production of a flammable gas mixture. Furthermore, the application in question does not describe a series of two sealing elements to form an inlet airlock. This is important, however, to prevent the uncontrolled ingress of ambient air or the escape of reaction gas.

[0006] Further patents of the applicant, such as DE 20 2008 006 737 U1, are also considered prior art. This patent presents a generic device which, in addition to an adjustment element in the reactor, also features improved air nozzles for introducing the oxidizing agent.

[0007] Several dozen wood gasification combined heat and power (CHP) plants are already in operation, utilizing a device known in expert circles as the "Joos gasifier." Economic viability presents a particular challenge, especially for these relatively small CHP plants. While the "Joos gasifiers" can be manufactured and operated relatively cheaply, experience has shown that the resulting, incompletely mineralized ash and its disposal costs represent a significant factor.

[0008] Many of these plants are operated in such a way that ash, as waste or residual material, is removed from the reactor along with the combustible gas mixture or wood gas, which undergoes post-treatment before being fed to a combustion engine. Often, a dust filter or similar device is used to clean the wood gas of ash, etc., thus ensuring trouble-free operation of the CHP unit and simultaneously automating the removal of the resulting ash.

[0009] This ash, with its carbon content of approximately 70%, is also known as black ash or coal dust. The consistency, quantity, and carbon content of this ash can vary depending on the wood gasification process. In the Joos gasifier, it is present as a powdery substance, with the majority of particles ranging in size from one micrometer to one millimeter. This substance is prone to clogging. Other components include polycyclic aromatic hydrocarbons (PAHs), which are absorbed by the coal dust through the condensation of tars in the combustible gas mixture. A 30 kW electrical output system produces approximately 70-120 liters of coal dust per day. Landfilling such material is prohibited by law, leaving only costly disposal options. This negatively impacts the overall economic viability of the system.

[0010] Further disadvantages include the problem of transport, which arises from the strong dust formation of the substance and the loss of energy in the form of carbon from the substance itself.

[0011] Related inventions, which include an element for the post-treatment of carbon-containing residues generated in a first process (this element can also be referred to as a post-treatment unit), are described, for example, in German patent applications EP 1 201 731 A1 and DE 10 2007 006 981 B4. Both devices pursue the same objective as the present application: to make gasification residues readily suitable for landfill disposal. However, unlike in the present invention, the post-treatment takes place in the same unit as the upstream first oxidation zone. This results in an unfavorable interaction between process step 1 and the post-treatment process. Furthermore, both gas generators are operated using fluidized bed technology.On the one hand, these are therefore very complex systems compared to the present patent specification; on the other hand, the post-treatment unit cannot be transferred one-to-one, since these are arranged below the fluidized bed without spatial separation by a flap or the like.

[0012] Likewise, post-treatment units according to patents EP 1 365 003 A1 or DE 20 2011 002 845 U1 cannot be operated on a system according to the preamble. The former is a device for the disposal and utilization of waste materials that may contain various pollutants. In a first process step, a carbon-containing melt is produced. The process referred to as post-treatment then aims to utilize or combust the contained carbon by injecting oxygen. However, a melt is not comparable to the black, carbon-containing ash of the device according to the invention. Due to the melt, the aforementioned system does not require a sealing element, for example, since the melt bath itself ensures an airtight seal for the reactor. The drain opening is simply located below the melt level.The device described in DE 20 2011 002 845 U1, unlike the invention presented here, has neither a flap nor an intermediate container for storing the residual material.

[0013] A further device for the thermal and material recovery of residues and waste materials is described in DE 44 46 803 A1. The starting material can again contain any type of pollutant, with the recovery taking place via several cascaded stages connected in succession, ultimately leading to a gasification reactor with an open flame reaction. Since the residue generated in a first process step is further processed using an entrained flow process, the disadvantages here are again the high cost and the lack of compatibility with the device according to the invention. Purpose and advantages of the invention.

[0014] The object of the invention, in contrast, is to propose a device for generating a combustible gas mixture from a carbon-containing feedstock, in particular from various types of wood, which improves upon the prior art and / or enables largely automatic and trouble-free operation. In an advantageous embodiment, greater economic efficiency is also achieved compared to the prior art.

[0015] This problem is solved, starting from a device of the type mentioned in the introduction, primarily by the features of claim 1. Advantageous embodiments and further developments of the invention are possible through the measures mentioned in the dependent claims.

[0016] Accordingly, a device according to the invention is characterized in that the inlet gate of the reactor feed unit and preferably the storage unit of the oxidation reactor have at least one sealing seal with a sealing surface oriented essentially in the direction of movement of the feed material or the residue. It has been found that during continuous operation – especially when using wood chips as feed material – leaks can occur from time to time at the feed opening or the filling opening of the storage device or the post-treatment unit and / or the inlet gate.

[0017] Such leaks impair the chemical reactions in the reactor / oxidation reactor. In contrast to conventional seals, which were oriented transversely to the direction of movement of the feedstock or residue and became leaky due to the accumulation of contaminants or other deposits such as wood chip fragments or sawdust, such impairment is effectively prevented by the sealing surface oriented according to the invention. This ensures gas-tight operation of the device or post-treatment unit even during continuous operation, thus leading to economical and reliable operation.

[0018] To prevent these leaks, in the described construction at least one closing element of the entrance lock seals against the sealing surface according to the invention at an end face or edge, so that the closing element enters the seal or along the sealing surface or is closed.

[0019] For this purpose, the closure element is designed such that it pivots about a pivot axis arranged outside the closure surface of the closure element and pivots or enters the seal with the sealing surface according to the invention with the end faces of the closure surface or the closure element to close the corresponding filling or feeding opening.

[0020] According to the invention, the seal or sealing surface is designed as a hollow cylinder within which the closing surface or closing element is arranged in the closed state and advantageously presses against the seal or sealing surface. This effectively prevents the accumulation of sawdust or dust in the area of ​​the sealing surface, or allows it to be removed or pushed away by retracting or pivoting the closing element according to the invention. This ensures a permanently tight seal even under the most difficult conditions when using wood chips or similar materials.

[0021] For example, the insertion or pivoting of the sealing element into the sealing surface aligned with the direction of movement of the starting material also removes stubborn sticky deposits, as this process essentially means scraping off the dirt lengthwise along the sealing surface.

[0022] Preferably, the device according to the invention has a post-treatment unit comprising an oxidation reactor having at least one oxidation zone for oxidizing the residual material, wherein at least one storage unit for storing the residual material is arranged between an entry opening of the post-treatment unit which can be closed in a substantially gas-tight manner with at least one closing unit and the oxidation reaction.

[0023] This measure ensures the most complete possible mineralization of the residual material, essentially producing a "white ash." The largely gas-tight sealing unit, which effectively seals the feed opening of the post-treatment unit, guarantees controlled oxidation within the oxidation reactor. This prevents unintended or detrimental reaction products that could potentially lead to more expensive disposal of the ash or waste materials from the post-treatment unit.

[0024] The advantageous storage unit, which is arranged downstream of the feed opening (which can be sealed as gas-tight as possible) in the direction of flow of the residue from the reactor, allows for the decoupling of the filling of the post-treatment unit from the feed of the residue to the oxidation reactor. Preferably, the post-treatment unit is filled discontinuously with a comparatively short opening time of the feed opening and a largely continuous feed of the residue to the oxidation or oxidation reactor. It has been shown that such an advantageous continuous filling of the residue to the oxidation reactor is highly beneficial for the complete mineralization of the residue or ash. This enables comparatively cost-effective disposal of the ash or waste materials generated by the post-treatment according to the invention. Consequently, the entire system is...The operation of the device for generating a flammable gas mixture from a carbon-containing starting material according to the invention is significantly improved compared to the prior art.

[0025] Numerous elaborate tests have demonstrated that a virtually gas-tight sealing unit and a storage unit are crucially advantageous, or even essential, to ensure the controlled, trouble-free, and, if necessary, continuous introduction of the residue or fine coal dust. Otherwise, the residue, coal dust, or embers would be adversely stirred up from / within the oxidation zone, causing air currents and turbulence that would then lead to the residue or fine coal dust being expelled from the post-treatment unit or the coal dust furnace through the feed opening.

[0026] In principle, the post-treatment unit can include, in addition to the oxidation reactor according to the invention, further process steps or components, such as one or more filter or cleaning stages, in particular cloth filters, gas scrubbers, oil baths, etc., and / or heat exchangers or coolers and / or catalysts or the like.

[0027] Preferably, the storage unit is arranged horizontally to the side of the oxidation reactor, or the feed of the residual material from the storage container or storage unit to the oxidation reactor is carried out horizontally to the side of the oxidation reactor. It has been shown that such a filling arrangement is advantageous for the oxidation process in the oxidation reactor.

[0028] Preferably, the post-treatment unit includes at least one conveying device for transferring the residual material from the storage unit to the oxidation reactor. This allows for controlled and preferably continuous filling of the oxidation reactor with residual material. This is beneficial for the oxidation of the residual material.

[0029] Advantageously, the conveying device has at least one drive motor for driving at least one conveying element. For example, an electric motor designed as a drive motor can be advantageously controlled and operated so that the feed or conveying of the residue to the oxidation reactor can be implemented as optimally and controlled as possible, and preferably continuously. Furthermore, the drive motor can also be used to effectively prevent or eliminate blockages, clumping, bridging, or similar issues with the residue or fine coal dust.

[0030] Alternatively or in combination with this, the feed of the residual material to the oxidation reactor can be achieved by gravity, for example by means of an incline or chute. That is, in this embodiment, the conveying device is designed as an incline or chute for the residual material and / or oxidized waste material, in accordance with the invention. For example, in a first advantageous embodiment of the invention, the conveying direction of the residual material between the storage unit and the oxidation reactor is designed as a conveying direction that descends at least partially in a vertical direction.

[0031] Alternatively or in combination with this, in a second advantageous variant of the invention, the conveying direction of the residual material between the oxidation reactor and a discharge opening for discharging waste material from the post-treatment unit is designed as a conveying direction of the residual material that descends at least partially in a vertical direction.

[0032] These two variants enable advantageous automatic or gravity-driven conveying of the residual material or oxidized waste through at least a part or section of the post-treatment unit. This is particularly beneficial in the hot or glowing oxidation zone of the post-treatment unit. This allows for very few, or even no, moving parts / components to be located in the oxidation zone. This increases operational reliability, as moving parts in the glowing or very hot oxidation zone can be subjected to high thermal stresses, which can lead to adverse effects or material wear.

[0033] Furthermore, gravity-driven conveying reduces both the design and economic costs.

[0034] In general, an (electro-)mechanically or motor-driven conveying device in the area of ​​the storage unit is advantageous in order to counteract or break up clumping and / or bridging of the residual material or fine coal dust. Thus, in a preferred embodiment of the invention, the storage unit has a conveying device for transporting the residual material, in particular at least one screw conveyor, a slide gate, a so-called scraper floor, or the like. A gravity-driven conveying or conveying unit is advantageous in the oxidation reactor or in the oxidation zone and / or in the discharge zone / section of the post-treatment unit.

[0035] The conveying device can also have a conveying direction that is at least partially vertical. This means that the oxidation reactor is preferably filled laterally by means of an ascending conveying device. This creates a space above the oxidation zone of the oxidation reactor where hot, rising gases or gas mixtures, as well as vapors, can collect and preferably condense without flowing or diffusing against the ascending conveying direction of the residue towards the reactor, in the direction of the storage unit or the closing unit of the post-treatment unit. This prevents moving components of the closing unit or the conveying device from being affected by corresponding chemical substances that can be formed as intermediate products in the oxidation reactor.According to this advantageous variant of the invention, the corresponding substances remain in the area of ​​the oxidation reactor and are, if necessary, at least partially reintroduced to the oxidation zone of the oxidation reactor by subsequent residual materials from the storage unit and are accordingly decomposed or oxidized.

[0036] Advantageously, the oxidation reactor or oxidation zone has at least one guiding element for directing, moving, or circulating the residue and / or waste material and / or the oxidizing agent or air. This helps prevent the residue from clumping, encrusting, or similar formations in the oxidation reactor or oxidation zone. It also ensures that the oxidation process is not impaired, meaning that the oxidation is as complete as possible and occurs over a large area, not just superficially. By moving, circulating, or stirring the residue, the entire residue is brought into advantageous contact with the air or oxidizing agent, particularly during gravity-driven conveying within the oxidation zone.

[0037] For example, the guiding elements can be designed as static or fixed elements and / or as ramps, crossbeams, etc., arranged at the bottom of the oxidation reactor, and / or as paddles, guide elements, struts, or rods, etc., arranged laterally and / or at the top of the oxidation reactor. This ensures effective circulation and contact with the oxidizing agent / air and can be implemented with minimal structural effort. Furthermore, the airflow in the oxidation zone can be advantageously guided or redirected / controlled using these guiding elements.

[0038] Advantageously, the housing of the post-treatment unit comprises at least one sieve element with numerous openings for the flow of air and / or oxidizing agent. This improves the flow of the air or oxidizing agent and also prevents, or minimizes, the discharge of residual material, which is often largely or entirely in the form of dust, from the post-treatment unit. Preferably, the sieve element is designed as a filter for filtering or retaining the residual material.

[0039] This allows the flow velocity of the air or oxidizing agent in the post-treatment unit to be significantly increased compared to a single, relatively large opening, without any residual material being discharged. A relatively high flow velocity of the air or oxidizing agent also leads to improved oxidation and advantageous mineralization, thus optimizing the production of white ash. Furthermore, a comparatively high flow velocity of the air or oxidizing agent contributes significantly to the advantageous functioning of the post-treatment unit or the pulverized coal furnace by ensuring, for example, a relatively rapid and as uniform as possible spread of the oxidation zone through sparks from already glowing residual material or pulverized coal. Additionally, a relatively high flow velocity allows more oxygen to enter the oxidation zone per unit of time.

[0040] Preferably, the sieve element is arranged between the oxidation reactor and the storage unit. The sieve element can be designed, for example, as a grid, mesh, fabric, steel cable or wire mesh, sieve, perforated sheet, or the like. In this way, the sieve element forms a defined beginning and / or end of the air or oxidizing agent flow path through the post-treatment unit. In a co-current flow variant of the invention, the sieve element is at least the beginning, and in a counter-current flow variant of the invention, the sieve element is at least the end of the air or oxidizing agent flow path within the post-treatment unit or the pulverized coal furnace according to the invention.

[0041] On the opposite side of the air or oxidizing agent flow path, a second opening or the second end / beginning can also be designed as a second sieve element or as a relatively large opening. It has been shown that a single sieve element, designed as a control element or flow control element, is sufficient to generate an advantageous flow or flow velocity within the post-treatment unit.

[0042] The second end or beginning of this flow path can advantageously also be designed as a discharge opening for the oxidized residue or waste material.

[0043] In a particular embodiment of the invention, the conveying device is designed as a scraper and / or cleaning unit for scraping or cleaning the screen element. The conveying device can, for example, extend from the area of ​​the storage unit to at least the screen element and / or to the oxidation zone, or even beyond, in order to simultaneously clean the screen element and remove or scrape off material or dust accumulations, or the like. This can advantageously be achieved by means of a screw conveyor, with the conveying path being designed as a pipe, a round conveying channel, or the like. The housing of the conveying path or the conveying channel encompasses the screen element, or numerous holes or openings are incorporated into the housing by means of drilling, laser cutting, punching, etc.

[0044] Advantageously, at least partially the conveying device or the conveying spiral and / or conveying channel and / or the guiding elements and / or the sieve element or the grid, sieve, net or the like are made of a heat-resistant material or of steel, in particular stainless steel, or ceramic or mineral fiber or of advantageous composite materials.

[0045] Optionally, the oxidation reactor includes at least one pyrolysis unit for the chemical transformation of the residue. It has been shown that certain chemically more complex compounds present in the residue can be advantageously at least partially chemically transformed or decomposed by pyrolysis. This measure allows even formerly more complex chemical compounds in the residue to be largely mineralized or decomposed in the post-treatment unit and, in particular, subsequently in the oxidation zone of the oxidation reactor.

[0046] In a particular embodiment of the invention, at least one level sensor is provided for measuring the fill level or fill degree of the storage unit and / or the oxidation reactor. Preferably, this level sensor is designed as a mechanically scanning level sensor. It has been shown that the control of the post-treatment unit and / or the oxidation reactor can be advantageously implemented using such a level sensor. A mechanically scanning level sensor is particularly distinguished by its high operational reliability.

[0047] In principle, compared to the prior art, the device according to the invention can significantly improve the economic efficiency of a device for producing a combustible gas mixture from carbon-containing feedstocks, in particular wood. This is made possible, among other things, by the advantageous oxidation of the resulting residue or coal dust outside the gasifier or reactor of the wood gasification plant.

[0048] After the oxidation of the coal dust in the post-treatment unit, i.e., in the so-called "coal dust furnace," a mineral waste material or waste product is present that is essentially free of harmful, toxic, or environmentally relevant pollutants, such as PAHs or the like, and / or advantageously has a carbon content of less than approximately 5%. This waste product of the post-treatment unit according to the invention can also be called "white ash." Compared to the coal dust, i.e., the residue from the gasifier, this "white ash" has a significantly smaller volume, can be disposed of cost-effectively due to its lower carbon content, and is considerably less prone to dust formation. Furthermore, energy in the form of heat is released during the oxidation of the coal dust, which can be advantageously utilized by the invention.

[0049] As a byproduct of the post-treatment or oxidation process according to the invention, an exhaust gas is produced that contains an increased amount of carbon dioxide. This exhaust gas is generally non-combustible and is similar, for example, to that of a wood-burning appliance. This exhaust gas can then be released into the open air or the atmosphere via a simple opening, chimney, or the like, or it can be fed to the wood gasification device or the gas engine.

[0050] In an advantageous embodiment of the invention, the heat generated during the post-treatment or oxidation of the residue or the coal dust can be further utilized by means of a heat exchanger unit. The heat exchanger unit can, in particular, comprise a cooling jacket, which is, for example, formed by a double-walled pipe and / or is arranged at least partially around the oxidation reactor and, if necessary, extending beyond it. The heat transferred by the heat exchanger unit can be supplied to a fluid, preferably to the cooling circuit of the combined heat and power plant.

[0051] Generally, the initial energy for starting the oxidation or igniting the oxidation zone can preferably be supplied at the airflow inlet, for example, using an external energy source such as a blowtorch or similar device. This process can take several seconds or minutes and is subsequently not required again for the entire duration of operation or during the oxidation process, as the oxidation can then advantageously proceed automatically. After an interruption of the oxidation, for example, due to a break in the feedstock, the oxidation must be restarted accordingly.

[0052] The oxidized residue or waste material from the post-treatment unit or the pulverized coal furnace, i.e., the white ash, can, for example, be transferred to a storage unit. This storage unit can be emptied and / or refilled automatically or manually, e.g., at regular or predetermined intervals, from the oxidation reactor.

[0053] In one embodiment of the invention, an advantageously closable discharge opening is provided for the post-treatment unit or the oxidation reactor. By opening the discharge opening, the storage unit can then be advantageously filled, preferably by gravity.

[0054] To solve the problem according to the invention, a device according to claim 1 and / or according to the preamble of claim 1 can be designed such that at least one adjustable grate device with a grate element rotatable eccentrically about an axis of rotation is provided. It has been shown that such an eccentrically rotatable grate device of the reactor and / or the oxidation reactor is / are of great advantage compared to previous grate devices according to the prior art.

[0055] Existing grate systems are sometimes designed to rotate centrally around a pivot axis or feature correspondingly centrally rotatable grate elements. However, impurities such as stones, nails, screws, or metal fragments, which are quite common in wood chips, have led to these grate systems becoming clogged or impaired over time, disrupting or impairing the production of the combustible gas mixture or wood gas. Initial tests have shown, however, that this is effectively prevented by an eccentric rotation of a grate element, particularly an upper grate element, preferably arranged vertically above a stationary second grate element. This facilitates the removal of residual material, dust / ash, and / or impurities produced in the reactor and / or oxidation reactor to the outside. This further increases operational reliability.This reduces the susceptibility to malfunctions of the reactor or oxidation reactor, resulting in a particularly economical operating mode.

[0056] It is also generally advantageous to have movable scrapers or similar devices arranged on the grate or grate assembly, or at a distance from it. These result in beneficial movement of the ember bed or oxidation zone of the reactor / oxidation reactor.

[0057] For example, when the grate elements alternate, each with at least one fixed and one movable element, the fixed grate elements can be fixed not only in the direction of rotation but also in the vertical direction. It has been shown that this advantageous design significantly reduces the weight load on the lower grate elements and greatly reduces wear.

[0058] According to the invention, the feed unit of the reactor, and advantageously the storage unit of the post-treatment unit or the oxidation reactor, comprises at least one, or at least two, inlet locks for the feed material or the residue arranged one behind the other in the direction of movement of the feed material or the residue. With such an advantageous inlet lock, it can be ensured that, for example, the device or the post-treatment unit, and thus the reactor or the oxidation reactor, never has free access to the atmosphere during filling or feeding. For example, one of the two closure elements of the inlet lock is always kept in a gas-tight closed state, while the other closure element is opened briefly if necessary. Preferably, the outwardly oriented "outer" closure element of the inlet lock is only briefly open for feeding or feeding.The filling port is open and otherwise designed to be largely gas-tight, closing the entrance lock.

[0059] The "inner" sealing element of the inlet lock can remain open for most of the operation, so that under normal operating conditions only the "outer" sealing element of the inlet lock ensures the gas tightness of the device or the post-treatment unit. The "inner" sealing element of the inlet lock is only closed for filling or feeding. During this process, the feedstock or residual material is temporarily stored in the inlet lock.

[0060] After the outer sealing element has been gas-tightly closed, the inner sealing element of the inlet lock can be reopened, allowing the stored material in the inlet lock to be conveyed, or preferably fall, into the storage device or the supply unit. The inner sealing element of the inlet lock can then remain open until the next loading or filling of the storage device or the supply unit. Example of implementation

[0061] An embodiment of the invention is shown in the drawing and is explained in more detail below with reference to the figures.

[0062] In detail: Fig. 1 a schematic representation of a device according to the invention up to the generation of the gas mixture, Fig. 2 a schematic representation of a device after gas mixture generation and with a first after-treatment unit according to the invention, Fig. 3 a schematic detail of an eccentrically rotatable grate of a device according to the invention, Fig. 4 a schematic representation of a device after gas mixture generation and with a second after-treatment unit according to the invention and Fig. 5 a schematic representation of a device after gas mixture production and with a third after-treatment unit according to the invention.

[0063] In Fig. Figure 1 shows a reactor 1, a feed unit 2 and only a section of a storage silo 3.

[0064] The starting material, for example, wood chips from waste or residual wood, are stored in the storage silo 3 in a manner not shown in detail. The storage silo 3 has a storage volume many times larger than the volume of a storage device 4 of the feed unit 2. The comparatively large volume of the silo 3 allows for the storage of wood chips for a relatively long operating time of the device according to the invention, such as one or more weeks or months.

[0065] If necessary, the wood in silo 3 is pre-dried using heat, in particular waste heat from reactor 1. Silo 3 may be designed as an open-topped storage area with a feeding device for feeding the device according to the invention or the like. The storage device 4 has, for example, a volume sufficient to operate reactor 1 for approximately several hours or about a day without opening a nearly gas-tight, rotatable flap 6 about a pivot axis 5, or without feeding from silo 3.

[0066] The wood chips are fed, for example, from silo 3 to the device according to the invention by means of a screw conveyor. For feeding, the largely gas-tight flap 6 is opened. The feeding phase can last a few minutes or seconds, in particular until the storage device 4 is partially filled and the flap 6 can be closed again almost gas-tight.

[0067] A level sensor 22 may determine the fill level of the storage device 4, e.g., a rotary paddle level sensor, ultrasonic sensor, or the like. Preferably, the flap 6 is actuated hydraulically, pneumatically, mechanically, and / or electrically, with a flap 6 that can be largely automatically controlled and actuated being advantageous.

[0068] The flap 6 seals against a sealing surface 7 at its end face. This sealing surface is oriented essentially parallel to the direction of fall or filling of the residual material and is designed as a hollow cylinder. During the closing process, the flap 6 retracts, removing any contaminants such as dust, sawdust, or the like from the sealing surface. This ensures a permanently gas-tight seal of the device according to the invention and / or of the intermediate storage tank 4. The seal is therefore self-cleaning.

[0069] The wood chips are transported or fed from the storage device 4 into the reactor 1 by means of a motor 8 and a screw drive or the like.

[0070] The screw drive can be fitted with both a heat exchanger for cooling the generated combustible gas mixture and a heat exchanger for recovering the heat contained in an exhaust gas stream of the gas engine not shown, in a manner not shown in detail.

[0071] The combustible gas mixture produced by reactor 1 is discharged from reactor 1 via a gas connection 9 to a gas engine (not shown in detail), whereby the gas mixture is first cleaned by a gas purification / gas filtration system, such as a cyclone, cloth filter, or the like, and mixed with air by means of an air mixer. The residue separated from the gas, or the ash produced by the gas purification, is fed to a post-treatment unit 30 according to Fig. 2 is administered. The follow-up treatment using unit 30 will be discussed in more detail below.

[0072] Reactor 1 comprises, in particular, an oxidation zone 10 and a reduction zone 11. To determine the fill level of the wood chips, reactor 1 has a level sensor 15. This sensor, acting as a mechanical sensor 15, can detect the fill level of reactor 1 and, at a predetermined fill level, actuate an electrical switching element, so that wood chips are fed into reactor 1 via the screw drive. Both phased and nearly continuous feeding of wood chips is possible.

[0073] The oxygen supply to the reactor or to the oxidation zone 10 is effected in particular by means of several, e.g. approximately five, air nozzles 16. The use of individual air nozzles 16 has the advantage that the air flowing through them leads to an advantageous cooling of the air nozzles 16, which eliminates the need for potentially complex cooling of the nozzles 16 and / or allows the use of relatively low heat-resistant materials for the air nozzles 16.

[0074] A largely gas-tight sealable service cover 13 is provided for igniting or burning the wood chips in reactor 1 and / or for maintenance or repair purposes.

[0075] The ember bed can be moved by means of a vibrating grate 19 that is at least partially rotatable about a pivot axis 20. Separate grate elements are provided, with an upper grate element 21 rotating eccentrically according to the invention by means of the motor-driven pivot axis 20. A lower grate element 23 is stationary. Fig. Figure 3 shows an enlarged view of the grate. The eccentric mounting of the rotating grate element 21, in comparison to the centrally mounted, stationary grate element 23, is also clearly visible. The generated gas mixture flows between the two grate elements 21 and 23, for which advantageous knobs or protrusions 24 are provided to form a clear passage for the gas. The gas then flows out through the gas outlet 9.

[0076] The gas carries ash, dust, particles, or the like, which are separated from the gas, for example, by means of a cloth filter or similar device; i.e., the gas is cleaned. According to the invention, this residual material is then oxidized or combusted in the aftertreatment unit 30 (see figure). Fig. 2) For this purpose, an oxidation reactor 31 is provided, which has air nozzles 32 for supplying oxidizing agent, preferably air.

[0077] Furthermore, unit 30 includes a storage unit 34 or an intermediate storage unit 34. Unit 30, or the storage unit 34, i.e., its filling opening 39, is sealed as gas-tight as possible during operation, which is achieved by means of an inlet airlock having at least two sealing elements. One of these sealing elements 36 has a rotary axis 45 arranged outside the sealing surface.

[0078] To fill unit 30, the largely gas-tight flap 6 is opened. The filling phase can take a few minutes or seconds, especially until the storage unit 34 is partially filled and the flap 36 can be closed again almost gas-tight.

[0079] A level sensor 42 may determine the fill level of the storage unit 34, e.g., a rotary paddle level sensor, ultrasonic sensor, or the like. Preferably, the flap 36 is actuated hydraulically, pneumatically, mechanically, and / or electrically, with a largely automated controllable and actuated flap 6 being advantageous.

[0080] The flap 36 seals against a sealing surface 37 at its end face. This sealing surface is oriented essentially parallel to the direction of fall or filling of the residual material and is designed as a hollow cylinder. During the closing process, the flap 36 retracts, removing any contaminants such as dust or similar substances from the sealing surface, thus ensuring a permanently gas-tight seal of the unit 30. The seal is therefore self-cleaning.

[0081] The residual materials are transported or fed from the storage unit 34 laterally and upwards into the oxidation reactor 31 by means of a motor 38 and a screw drive or the like.

[0082] The exhaust gas produced by oxidation reactor 31 contains some flammable components and can therefore be fed to reactor 1 and / or the gas engine (not shown in detail). The exhaust gas from oxidation reactor 31 can also be released into the atmosphere via an exhaust pipe, chimney, etc. Exhaust gas cleaning may be necessary to comply with legal regulations.

[0083] The oxidation reactor 31 comprises an oxidation zone 40, particularly in the area below the air nozzles 32 or directly above the grate. Since the residue rests directly on the grate and generally oxidizes or burns on the outer surface, a ring of glowing material forms on the grate. A scraper or similar device (not shown in detail in the figure) advantageously moves the residue or powdery ash from above, downwards through the feed chute, essentially from the center, to the outside, thus feeding the glowing material ring. Burned material or residue preferably falls downwards around the periphery and can be collected and / or preferably automatically removed from the oxidation reactor.

[0084] To determine the fill level of the residual material, the oxidation reactor 31 has a level sensor 35. This sensor, acting as a mechanical sensor 35, can detect the fill level of the oxidation reactor 31 and, at a predetermined fill level, actuate an electrical switching element, so that residual materials are fed into the oxidation reactor 31 via the screw drive. Both phased and nearly continuous feeding of residual materials is possible.

[0085] Oxygen is supplied to the oxidation reactor 31 or to the oxidation zone 40, in particular by means of several, e.g. approximately five, air nozzles 36. A service cover 33, which can be sealed largely gas-tight, is provided for igniting or burning off the residues in the oxidation reactor 31 and / or for maintenance or repair purposes.

[0086] The ember bed can be moved by means of a vibrating grate 19 that is at least partially rotatable about a pivot axis 20. Separate grate elements are provided, with an upper grate element 21 rotating eccentrically according to the invention by means of the motor-driven pivot axis 20. A lower grate element 23 is stationary. As already mentioned, the oxidation reactor can have a movable, and in particular rotatable, scraper arranged above a stationary grate element, optionally with several curved or spiral wings or the like, for moving the residue or ash outwards in a radial direction to form an advantageous ring of embers.

[0087] In Fig. Figure 3 shows an enlarged illustration of an alternative embodiment of a grate, which also means that the two grates of reactor 1 and oxidation reactor 31 can be identically designed. The eccentric mounting of the rotating grate element 21 is also clearly shown in comparison to the centrally mounted, stationary grate element 23. In oxidation reactor 31, however, the generated gas mixture advantageously flows outwards or circumferentially and through a gas outlet 39.

[0088] In a second advantageous embodiment of a post-treatment unit 30 or a pulverized coal furnace 30 according to the invention, residual material 50 or pulverized coal 50 from the gasifier 1 is moved largely uniformly over one or more surfaces 52 by means of one or more conveying or moving units 51, which are arranged, for example, centrally or laterally, using rotating screw conveyors 53 or movable slides, buckets, or plates. The air 54 used for oxidation flows in the same direction as, or in the conveying or moving direction 55 of, the pulverized coal 50 and exits through an outlet or opening 39 in the lower part of the post-treatment unit.

[0089] Furthermore, a housing 57 is provided which may optionally house a heat exchanger unit 58 (see Fig. 5) exhibits. The housing 57 extends (without further illustration) advantageously perpendicular to the plane of the leaf such that the surfaces 52 are realized as relatively large planes. Accordingly, a large reaction surface of the residue 50 with the air 54 is realized.

[0090] In the variant according to Fig. 4 This housing has comparatively large inlet openings 59 for the inflow of air 54. In this embodiment, a relatively large oxidation surface can be created in a comparatively small space. As a result, the air 54 for oxidation can be moved at a comparatively low velocity, whereby little or no coal dust 50 is captured and carried along by the airflow 54.

[0091] The movement units 51 can also be used to close off the storage unit 34 from the oxidation reactor 40 or the oxidation zone 40. Fig. Figure 4 also shows that the surfaces 52 are inclined downwards with respect to the horizontal plane or descend vertically. This allows the residual material to be easily pushed by the movement units 51 in the area of ​​the oxidation reactor 40 or the oxidation zone 40 over the surfaces 52, which are inclined at, for example, approximately 2° to 25°, and falls into a collection chamber 60. The oxidized residual material, i.e., the waste material 61 or the white ash 61, is collected here. Without further detail, a discharge flap or similar device can be provided by means of which the white ash is discharged or removed from time to time and disposed of or deposited.

[0092] In the embodiments according to the invention, a nearly gas-tight closing unit 36 ​​in the form of two superimposed flaps (not shown), one of which is designed as a rotary flap 36, a sealing surface 37, and a storage unit 34 are of decisive advantage in order to ensure a controlled and, for example, continuous or discontinuous introduction of the coal dust 50 into the post-treatment unit 30. Otherwise, uncontrolled air currents could cause the coal dust 50 in the storage unit 34 to oxidize or escape from the inlet opening 39.

[0093] The heat generated during the oxidation of coal dust 50 can be dissipated via the airflow 54 and preferably supplied to the cooling circuit of the combined heat and power plant via a heat exchanger 58.

[0094] Furthermore, one or more conveying spirals 53 can be located in the storage unit 34 of the post-treatment unit 30. These spirals may also serve as storage units 34 and advantageously ensure a uniform distribution over the entire length (perpendicular to the plane of the blade) of the pulverized coal furnace 30. A conveying spiral can also be used in the lower section or in the collection chamber 60 (without further description). This has proven advantageous for discharging white ash.

[0095] In general, the pulverized coal furnace 30 should be made of a relatively heat-resistant material. The initial energy for igniting the oxidation of the oxidation zone 40 is preferably supplied at the inlet 59, 39 of the airflow 54, e.g., using a blowtorch or similar device. This process can take several seconds or minutes and is subsequently not required again for the entire duration of operation.

[0096] The waste material 61 from the pulverized coal furnace 30, or the white ash 61, can enter a storage unit (not shown) where it is stored. This storage unit can be emptied automatically or manually at regular intervals.

[0097] In Fig. Figure 5 schematically depicts a third variant of a post-treatment unit 30 according to the invention. Here, comparable components are provided with the corresponding reference numerals of the aforementioned embodiments of the invention. In this particular embodiment of the pulverized coal furnace 30, the pulverized coal 50 is moved through a conveying tunnel 65 or conveying channel 65 by means of a conveying spiral 53. The air 54 required for oxidation is moved in the opposite direction to the conveying movement 55 of the residue 50 or the conveying spiral 53 and exits the post-treatment unit 30 via a sieve element 63, e.g., a grid, sieve, mesh, or the like, wherein the sieve element 63 is arranged on the conveying tunnel 65 and / or extends at least partially around it.

[0098] This advantageous sieve or filter element 63 allows a relatively high air velocity to be achieved in the conveying tunnel 65 without (a significant amount of) coal dust leaving the coal dust furnace 30. The air velocity advantageously contributes to the optimal functioning of the coal dust furnace 30 by, for example, ensuring a rapid and uniform distribution of the oxidation zone 40 through a certain amount of sparking from already glowing coal dust 50. Furthermore, a relatively high flow velocity allows more oxygen to enter the oxidation zone 40.

[0099] By arranging or attaching the filter element 63 to an outer wall 57 of the conveying tunnel 65, it is cleaned or scraped by the auger 53. It has been shown that this effectively prevents the filter element 63 from becoming clogged or blocked.

[0100] In this design as well, a virtually gas-tight closing unit 36 ​​and a storage unit 34 are of decisive advantage in order to ensure the most controlled and / or continuous introduction of the coal dust 50. Otherwise, the coal dust 50 or embers from the oxidation zone 40 may be stirred up, which could then, due to adverse air currents 54, leave the coal dust furnace 30 through the feed opening 39.

[0101] The heat generated during the oxidation of coal dust 50 can be supplied to a fluid, preferably to the cooling circuit of the combined heat and power plant, via a cooling jacket 58, which can be, for example, a double-walled pipe.

[0102] The waste material 61 from the coal dust furnace 30 or the white ash 61 can exit at the end of the conveying tunnel 65 and, for example, enter a storage unit where it is stored.

[0103] The screw conveyor 53 or the conveying device 51 is driven by an electric motor (not shown in detail). Initial tests have shown that it is advantageous for the storage unit 34 to be emptied mechanically, i.e., that the residual material 50 is fed to the oxidation zone 40 by means of a mechanical drive or conveying mechanism. This effectively prevents clumping, crusting, or bridging of the sometimes very fine residual material 50 or coal dust 50.

[0104] In a preferred embodiment of the invention, which is not described in detail, the two variants can be combined according to Fig. 4 and Fig. 5 are advantageously combined with one another. This means that the storage unit 34 is emptied mechanically, e.g. by means of a screw conveyor 53, wherein the conveying device 51 or screw conveyor 53 extends only to before or only to the beginning of the oxidation zone 40. That is, compared to the variant in Fig. 5 is “cut off” or shortened. This advantageously ensures the (controlled) emptying of the storage unit 34 and simultaneously protects the conveying device 51 or auger 53 from high thermal stress in the very hot oxidation zone 40 or in the oxidation reactor 40. Furthermore, the costs for correspondingly long conveying devices 51 or augers 53 are avoided.

[0105] The transport in oxidation zone 40 or in oxidation reactor 40 takes place according to the variant as per Fig.4, i.e. by means of gravity or by an inclined or sloping arrangement of the oxidation zone 40 or the oxidation reactor 40 and thus the surface 52. Accordingly, residual material 50 or coal dust 50 is mechanically driven into the oxidation zone 40 or into the oxidation reactor 40 and then pushed through the conveying tunnel 65 or the material to be oxidized slides through the tunnel 65 automatically and out of the rear or out of the opening 39.

[0106] For example, in the area of ​​the oxidation zone 40 or in the oxidation reactor 40, guiding elements such as ramps or the like can be arranged on the floor or surface 52 so that the material or coal dust 50 sliding or conveyed over them is moved or churned. This positively influences the oxidation process. Alternatively or in combination with this, guiding elements such as sheets and / or rods, etc., can also be provided on the side or on the upper ceiling area of ​​the conveying tunnel 65 or the oxidation zone 40 or the oxidation reactor 40, which advantageously project into the residue 50 or, if necessary, extend to the surface 52 and can thus also generate a movement or churning of the residue 50 or coal dust 50 in the area of ​​the oxidation zone 40 or in the oxidation reactor 40.

[0107] In principle, the resulting exhaust gas and / or the outflowing air 54 can be collected or combined and released into the atmosphere via a chimney or similar device (not shown in detail). This exhaust gas is generally non-combustible. Utilizing the heat from the exhaust gas can improve the heat utilization and overall efficiency.

Claims

[1] Device for producing a flammable gas mixture from a carbon-containing starting material, comprising a feed unit (2) for supplying the starting material to a reactor (1), wherein the reactor (1) comprises at least one oxidation zone (10) for oxidizing the starting material and a reduction zone (12) for reducing at least one intermediate product of the oxidation, wherein the feed unit (2) comprises at least one storage device (4, 34) for intermediate storage of the starting material, which has at least one opening (9, 39) for introducing the starting material, wherein the opening (9, 39) can be closed with a closure element (6, 36) which interacts with the sealing surfaces (7, 37) of a seal in the area of ​​a closure surface, characterized by, that the feed unit (2) has at least one inlet lock arranged in the direction of movement of the feed material and comprising at least two gas-tight sealing elements (6, 36), and that at least one sealing element (6, 36) seals against a sealing surface (7, 37) of the seal which is designed as a hollow cylinder and is oriented substantially in the direction of movement of the feed material, and that the sealing element (6, 36) enters the seal along the sealing surface (7, 37) and is pivotable about a rotation axis (5, 45) arranged outside the sealing surface. [2] Device according to claim 1, characterized by, that the reactor (1) comprises at least one output unit (9) for outputting a carbon-containing residue (50) and that at least one after-treatment unit (30) is provided for after-treatment of the residue (50), which comprises at least one oxidation reactor (31) having at least one oxidation zone (40) for oxidizing the residue (50) and that at least one storage unit (34) for storing the residue (50) is arranged between an input opening (39) of the after-treatment unit (30) that can be closed in a substantially gas-tight manner with at least one closing unit (36) of the oxidation reactor (31, 40). [3] Device according to claim 2, characterized by , that the storage unit (34) is arranged laterally on the side of the oxidation reactor (31). [4] Device according to claim 2, characterized by, that the post-treatment unit (30) comprises at least one conveying device (51, 53) for conveying the residual material (50) from the storage unit (34) at least to the oxidation reactor (31, 40) and that the conveying device (51, 53) has at least one drive motor for driving at least one conveying element (53). [5] Device according to claim 2, characterized by , that a conveying direction (55) of the residual material (50) between the storage unit (34) and the oxidation reactor (31) is designed as a conveying direction (55) of the residual material (50) that descends at least partially in a vertical direction. [6] Device according to claim 2, characterized by , that a conveying direction (55) of the residual material (50) between the oxidation reactor (31) and a discharge opening (39) for the discharge of a waste material (61) of the post-treatment unit (30) is designed as a conveying direction (55) of the residual material (50) that descends at least partially in a vertical direction. [7] Device according to claim 4, characterized by , that a housing (57) of the post-treatment unit (30) comprises at least one sieve element (63) having numerous openings for the flow of air (54) and / or oxidizing agent. [8] Device according to claim 7, characterized by , that the conveying device (51,53) is designed as a scraper and / or as a cleaning unit for scraping or cleaning the sieve element (63). [9] Plant for generating heat energy and / or electrical energy comprising a device for generating a combustible gas mixture from at least one carbon-containing feedstock, an internal combustion engine for burning the gas mixture and / or a generator for generating electrical energy, characterized by that the device is designed according to one of the aforementioned claims.

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