Downstream qasifier with multi-axis actuated bed interface to the reduction zone

Description

[0001] The present invention relates to a fuel gas generator acting as a gasifier and preferred as a downstream gasifier for the gasification of various solid fuels preferred such as bio fuels from wood or other sources but not limited to this, to supply at least one propulsion engine with a fuel gas which is, for the regular operation of the propulsion engine, at least partially one source of fuel, whereby the propulsion engine is a combustion engine, and whereby the combustion engine, in particular driving an energy conversion unit to transform mechanic energy into another form of energy, is connected to one or more energy consumers. In favor, this energy consumer can be a generator to generate electric energy. The gasifier's thermo- chemical reduction zone does not contain a conventional bed in its lower end, as it is known from other gasifiers. Instead, it is built as a horizontal rotating and oscillating as well as vertical oscillating device which can be actuated in a controlled and free manner against the fixed parts of the gasifier's components, especially the thermo- chemical reaction pipe of the gasifier of which the described invention is the floor bed.

State of the art

[0002] For more than 60 years it is now known and published that fixed bed gasification reactors can be equipped with rotating beds which can also include numerous fingers which reach into the reduction zone to improve the homogeneity of the gasification process and to prevent from "dead zones". Especially Dr.-lng. Brill, Dipl.-lng. Linneborn and Dr. Spengler from the lmbert Gesellschaft describe the underlaying physical principles as well as detailed design solutions in their patent Nr. 235261 , which was issued 16. March 1945 from the Eidg. Amt fuer Geistiges Eigentum of Suisse. More than 60 years later, Thiessen et al. were able to claim the same principles and technologies in their US patent US 2007/0169411A1 which was published 26 JuI 2007. Both patents claim rotating beds which essentially rotate perpendicular to the shaft to facilitate even heating and gasification of the fuel. Also in their patent Thiessen et al. "inverted" the well known old lmbert patent, utilizing an application for upstream gasification. On page 4 (90) to page 5 (18) the lmbert patent Nr. 235261 claims detailed that the perpendicular rotation is not limited to a constant speed rotation but also includes oscillating rotation and uneven rotation. Also it states that the geometry of the finger, acting as mixer for the bed, is not limited to the number one and not limited to the given geometry in the attached example. Further, the given example relates close to the claimed solution in US 2007/0169411 Al Both claim that their technical solutions enable homogenous burn-off and prevent inhomogeneous thermal operating performance.

Background and description of the invention

[0003] Rotating beds and fingers are not a new approach and there have been invented many gasifier systems showing such features. However these technical solutions are limited where high dynamic of the gasification process is required, for instance for electric power generation in insulated grids. Another aspect is that these technical solutions are limiting the suitability of the gasifier and the power generation system for different solid fuel sources, for instance such as wood-waste, residues from winery or seed oil manufacturing, or coal or peat.

[0004] Another most important aspect is the robustness of the gasification apparatus in terms of maintenance free operation time, reliability, and cost effectiveness. Ideally, the apparatus needs to self adjust its geometry to compensate for wear, slagging, contamination with foreign inert material, and optimized gasification efficiency with regard to required power output and specific properties of the input material.

[0005] Therefore, in view of the foregoing, it is desirable to have an improved gasification system that solves these and other problems of the prior art.

[0006] Therefore, the primary feature or advantage of the present invention is an improved gasifier, economical to operate and durable in use.

[0007] Another feature or advantage of the present invention is the provision of a gasifier that more uniformly heats and distributes the material inside the reactive zone to improve efficiency and dynamic.

[0008] Another feature or advantage of the present invention is to improve the gaseous oxidation agents through the fuel material.

[0009] These and the other features or advantages of the present invention are described and claimed in the following.

[0010] The embodiment of the gasification reactor (gasifier) exemplarily shown in figure 1 is a downstream fixed bed gasifier used to generate energy. In this conventional gasification apparatus the bottom of the reactor which is the bed, can be a fixed bed or a rotating bed as described in Suisse patent Nr. 235261 , issued 16. March 1945. The gasifier's outer shell (2) contains the components and parts of the gasifier and provides a gas sealed confinement. Pipe-style feedthroughs (3) supply the gaseous oxidation agent into the oxidation zone (5) of the thermo-chemical reactor. Downstream, the thermo-chemical reaction pipe features the area of the reduction zone (10). The gaseous oxidation agent flows (4) through the oxidation zone, where it chemically and exothermically reacts with the solid fuel, and which likewise falls downstream through the gasifier (1). In the reduction zone (10) the

Boudouard- and water-gas reactions will reform the final fuel gas with its high content in carbon monoxide, hydrogen and some methane as well as inert components such as water or carbon dioxide or nitrogen. A device to remove ash and other particle residues is exemplarily given in (8) which is a screw conveyor. The suction pipe (9) removes the raw fuel gas from the gasifier and is connected to a de-dusting device. The bed (6) which can be a rotating bed, features a fix gap (7) towards the thermo- chemical reaction pipe, which allows fuel gas as well as ash and particles to exit the thermo-chemical reaction pipe and to enter the bottom area of the gasifier.

[0011] The present invention relates to the family of not fixed bed gasifiers. The present invention can be used in systems such as shown in figure 2. However, the present invention can be used in any type of system where a gasifier for gasifying solid fuels is desired.

[0012] Figure 3, 4, 5, 6 and 7 show cut away side views of the lower part of the described downdraft gasifier to illustrate the invention.

[0013] As in figure 1 the gasifier assembly in figure 3 features an assembly's outer shell (2) which is not completely drafted in figure 3. Figure 3 shows the important changes and improvements to the gasifier. The bed (6) with the fix gap (7) of the gasifier in figure 1 is replaced by the piston-like rotating stroke-bed (21). This stroke- bed features a brush-assembly (22) in the lower section and a cone shaped upper part with a stir-head (23). Between the thermo-chemical reaction pipe and the piston- like rotating stroke-bed the gap δ exists through which the fuel gas and particles like ash etc escape from the thermo-chemical reaction pipe and then will be sucked through the fuel gas outlet pipe (9). In this particular assembly the gap-width δ is fixed and constructive given. However the length z of the gap is a function of the vertical movement of the bed in X-axis. The flow resistance of the fuel gas-particle mixture through this gap is a gasifier performance influencing factor, and is depending on the length of z which can be varied completely free by a stroke h of the bed in X-axis. The material of the piston-like rotating stroke-bed in this invention features a low thermal conductivity as for instance ceramic materials do. Further the piston-like rotating stroke-bed can move free in X-direction. As an additional cleaning function the total stroke of the device allows to either completely remove the bed from the thermo-chemical reaction pipe or to completely insert the bed into the thermo-chemical reaction pipe, in a way that the brush (22) can clean the inner surface of the pipe. Further the piston-like rotating stroke-bed can be rotated free around its vertical axis. The rotation speed ωo can be chosen in both spinning directions and free in value. Further both motions the rotation and the vertical oscillation of the piston-like rotating stroke-bed can completely free be superpositioned. This motion, for example can be transferred via the beds shaft at the bottom which can for instance be mounted to a hydraulic device or be part of a hydraulic device or all other suiting devices to create and to transfer speed-varied multi-axis movements. As the flow resistance through the gap is controlled by the device, it also becomes an efficient method to compensate for wear and plugging.

[0014] As in figure 1 and figure 3 the gasifier assembly in figure 4 also features an assembly's outer shell (2) which is not completely drafted, too. Figure 4 shows another important configuration of the changes and improvements to the gasifier. Again, the bed (6) with the fix gap (7) of the gasifier in figure 1 is replaced by the piston-like rotating stroke-bed (21). In this application the thermo-chemical reaction pipe (24) and the stroke bed feature a conical shape (25) with the same flank gradient over the entire length z, as shown in the left part of the assembly in figure 4. Alternative, as shown in the right part of the assembly in figure 4, the thermo- chemical reaction pipe (24) and the stroke bed feature a conical shape (26) with different flank gradients over the length. Between the thermo-chemical reaction pipe and the piston-like rotating stroke-bed the gap 6 ₂ exists through which the fuel gas and particles like ash etc. escape from the thermo-chemical reaction pipe and then will be sucked through the fuel gas outlet pipe (9). Additionally, the stroke bed may feature a shape which improves mass transportation through the gap δ ₂ between thermo-chemical reaction pipe and stroke bed when the stroke bed moves or rotates as for instance screw conveyor blades do. An essential feature of this particular assembly is that the gap-width δ ₂ is varied and controlled by the stroke movement of the head of the stroke-bed in X-axis. As indicated, the flow resistance through the gap δ ₂ is a gasifier performance influencing factor, and is depending on the length of z, which both can be varied by a variation of the stroke h of the bed in X-axis. The material of the piston-like rotating stroke-bed in this invention features a low thermal conductivity as for instance ceramic materials do. Further the piston-like rotating stroke-bed can move free in X-direction. As an additional cleaning function the total stroke of the device allows to either completely remove the bed from the thermo- chemical reaction pipe or to insert the bed into the thermo-chemical reaction pipe, in a way that the gap gets completely closed and the surfaces of bed and pipe get into physical contact, removing contaminations of particles and plugged ash by rubbing and scuffing. Further the piston-like rotating stroke-bed can be rotated free around its vertical axis. The rotation speed ωo can be chosen in both spinning directions and free in value. Further both motions the rotation and the vertical oscillation of the piston-like rotating stroke-bed can completely free be superpositioned. This motion, for example can be transferred via the beds shaft at the bottom which can for instance be mounted to a hydraulic device or be part of a hydraulic device or all other suiting devices to create and to transfer speed-varied multi-axis movements. As the flow resistance through the gap is controlled by the device, it also becomes an efficient method to compensate for wear and plugging.

[0015] As in figure 1, 3 and 4 the gasifier assembly in figure 5 also features an assembly's outer shell (2) which is not completely drafted, too. Figure 5 shows another important configuration of the changes and improvements to the gasifier. Again, the bed (6) with the fix gap (7) of the gasifier in figure 1 is replaced by the piston-like rotating stroke-bed (21). In this application the thermo-chemical reaction pipe (28) and the stroke-bed (27) features a conical shape with the same flank gradient over the entire length z. The important change to the assemblies in figure 3

and 4 are that the piston-like stroke bed is formed as a closed conical cylindrical pot, encompassing the likewise conical cylindrical shaped thermo-chemical reaction pipe from the outside. Additional the stroke-bed may feature a shape which improved mass transportation when rotating as for instance a screw conveyor does. Between the thermo-chemical reaction pipe and the piston-like rotating stroke-bed the gap δi exists through which the fuel gas and particles like ash etc are escaping the thermo- chemical reaction pipe and the sucked through (9). In this particular assembly the gap-width δ and the length z of the gap is varied by the stroke movement of the head in X-axis. As shown before, the flow resistance is a gasifier performance influencing factor, and is depending on the length of z and gap-width δ which can be varied by a stroke h of the bed in X-axis. The material of the piston-like rotating stroke-bed in this invention features a low thermal conductivity as for instance ceramic materials do so. Further the piston-like rotating stroke-bed can be moved free in X-direction. As an additional cleaning function the total stroke of the device allows to either completely remove the piston-like stroke bed, formed as a closed conical cylindrical pot, from the likewise outside conical shaped thermo-chemical reaction pipe or to completely impose on it, that the gap gets closed and the surface of the pipe contacts the bed. Further the piston-like rotating stroke-bed can be rotated free around its vertical axis. The rotation speed ω ₀ can be in both directions and free in value. Further both motions the rotation and the vertical oscillation can completely free be superpositioned. This motion, for example can be transferred via the beds shaft at the bottom which can for instance be mounted to a hydraulic device or be part of a hydraulic device or all other suiting devices to create and to transfer oscillating multi- axis movements. As the flow resistance through the gap can be controlled by the device, it also becomes a method to compensate for wear and plugging.

[0016] As in figure 5 the gasifier assembly in figure 6 shows the same features as described in [0015]. However, in addition to this, the piston-like stroke bed is formed as a closed conical cylindrical pot, with an additional geometric hollow sink in the inner centre (29), allowing potentially intruded foreign particles such as for instance nails, screws, stones etc. to rest in a neutral location, preventing the whole system from a malfunction due to blockage or scuffing.

[0017] The gasifier assembly in figure 7 is a superposition of the assemblies shown in figure 3, 4 and 5, featuring the sum of the described features in [0013], [0014] and [0015].

[0018] The invented assemblies feature functional properties which allow to control the amount of fuel gas flow through the gasifier by varying the flow resistance of the gap between bed and thermo-chemical reaction pipe.

[0019] The invented assemblies also feature functional properties which allow to remove contaminations from the thermo-chemical reaction pipe and the surfaces of the gap by varying the width of the gap in combination with a superimposed rotation.

[0020] The invented assemblies also feature functional properties which allow to adjust and compensate for the wear and thermal elongation of the gap by varying the width of the gap in combination with a superimposed rotation.