Built-in heat exchange double fluidized bed reaction device

Abstract

The invention discloses a built-in heat exchange double fluidized bed reaction device, which is used for a biomass raw material hydrogen production process, and comprises: a gasification chamber, which is of a cylindrical structure and is provided with a conical surface at the bottom, and the conical surface is provided with a hole for introducing bubbling fluidizing air; the combustion chamber is of a tubular structure and is arranged in the gasification chamber in a sleeved mode, the bottom of the combustion chamber is in an open state, and the combustion chamber is arranged in the conical surface area and used for introducing vertically-upward combustion-supporting air; the material returning units are arranged at the upper part of the reaction device, are uniformly arranged along the circumferential direction and are used for carrying the high-temperature bed material particles from the combustion chamber to an annular gasification area outside the combustion chamber and mixing the high-temperature bed material particles with biomass raw materials in the gasification area to produce hydrogen; the material returning unit is provided with a loosening chamber and a material returning chamber, and a bottom plate of the loosening chamber is obliquely arranged towards the material returning chamber. Through the built-in design of the double fluidized beds, the feeding pipe and the return feeder are prevented from being exposed at room temperature, and the heat loss of the reactor is reduced; and meanwhile, the device can provide enough regeneration time for the bed material under the condition of keeping a relatively high solid conveying rate.

Description

Technical Field

[0001] The invention relates to the technical field of biomass hydrogen production, and in particular to a built-in heat exchange double fluidized bed reaction device. Background Art

[0002] As a highly efficient and clean energy source, the development of hydrogen energy is timely. Among the various technical routes for producing hydrogen using biomass as raw materials, the prospect of using fluidized bed reactors for efficient thermal conversion to produce hydrogen-rich gas is relatively promising.

[0003] The application of double fluidized bed has already existed in the prior art. The double fluidized bed reactor has the following advantages: it decouples combustion and gasification, performs indirect heating, and has a high hydrogen production rate; there is only efficient exchange of solids and heat between the combustion chamber and the gasification chamber, and high heat flux and high processing capacity can be achieved in a smaller volume; the tar content is lower than that of the conventional route, which is convenient for subsequent detarring treatment.

[0004] Chinese patent application CN109704278A discloses a device and method for preparing hydrogen by pyrolysis and gasification of biomass in a double fluidized bed. The double fluidized bed includes a fluidized bed pyrolysis furnace and a fluidized bed combustion furnace. The fluidized bed pyrolysis furnace includes a pyrolysis furnace riser. The rear end of the pyrolysis furnace riser is connected to a pyrolysis furnace cyclone separator. The upper part of the pyrolysis furnace cyclone separator is connected to a conversion reactor, and the lower part is connected to a pyrolysis furnace return valve. The other outlet of the pyrolysis furnace return valve is connected to a fluidized bed combustion furnace. The fluidized bed combustion furnace includes a combustion furnace riser; the other outlet of the pyrolysis furnace return valve is connected to the bottom of the combustion furnace riser; an oxygen carrier cyclone separator is arranged in the middle of the combustion furnace riser, and a CO2 absorbent cyclone separator is arranged on the top; in the preparation process of this scheme, pure oxygen is not required as a gasifying agent. The system only needs to supplement air as gasification to meet production needs. The production cost is low, and the pyrolysis furnace does not use air for fluidization, and the content of effective components in its biomass fuel gas is high.

[0005] The existing dual fluidized bed separates the gasification chamber from the combustion chamber, and uses a feed pipe and a return feeder to exchange heat with the bed material. During the transportation between the two fluidized beds, a certain amount of heat loss will occur, making it impossible for the biomass raw materials with low calorific value to be supplied to the gasification reaction through the combustion of residual carbon, and additional fuel needs to be added to the combustion chamber. This has led to a reduction in economic efficiency; in addition, during the process of transporting the low-temperature bed material particles to the combustion chamber, the tar adhered to the surface becomes more viscous when the temperature drops, making it easy for the particles to become compacted and bridged, blocking the reactor feed pipe, affecting the circulation of the reactor, and restricting the operation cycle of the device.

[0006] In addition, since the regeneration of AER bed material (compared with ordinary dual fluidized bed technology, AER technology has three additional effects: absorption, enhancement, and reforming) takes a certain amount of time, and the combustion chambers of existing dual fluidized bed devices are mostly fast fluidized beds, although a relatively high solid transport rate can be maintained, the bed material regeneration time is short.

[0007] Furthermore, the returner used in the existing double fluidized bed has a small loose chamber volume and fluidization dead zones are prone to occur at the corners. During the biomass hydrogen production process, the coke particles in the solid particles in the returner are prone to form agglomeration with the biomass particles, causing coking.

[0008] Therefore, there is an urgent need for a built-in heat exchange double fluidized bed reaction device that avoids the use of an external feed pipe and avoids the feed pipe and return device from being exposed to room temperature, thereby reducing reactor heat loss, improving the economy of the route and the operating cycle of the device; while maintaining a high solid transport rate, sufficient regeneration time can be given to the bed material; and the coking phenomenon during the return process can be effectively reduced.

[0009] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0010] The purpose of the present invention is to provide a built-in heat exchange double fluidized bed reaction device, which changes the external double fluidized bed into a built-in type, avoids the feed pipe and the return device from being exposed to room temperature, and reduces the heat loss of the reactor; at the same time, the device can give the bed material sufficient regeneration time while maintaining a relatively high solid conveying rate.

[0011] Another object of the present invention is to provide a built-in heat exchange double fluidized bed reaction device, which can effectively avoid the fluidization dead zone of the loose chamber in the return unit.

[0012] To achieve the above-mentioned purpose, the present invention provides a built-in heat exchange double fluidized bed reaction device for use in a biomass raw material hydrogen production process, comprising: a gasification chamber, which is a cylindrical structure and has a conical surface at the bottom, and the opening on the conical surface is used to introduce bubbling fluidizing air; a combustion chamber, which is a tubular structure and is sleeved in the gasification chamber, and the bottom of the combustion chamber is in an open state and is arranged in the conical surface area, for introducing vertically upward combustion-supporting air; a return unit, which is arranged at the upper part of the reaction device, and the number is multiple and evenly arranged along the circumference, for transporting high-temperature bed material particles from the combustion chamber to the annular gasification zone outside the combustion chamber and mixing with the biomass raw materials in the gasification zone to produce hydrogen; the return unit is provided with a loosening chamber and a return chamber, and the bottom plate of the loosening chamber is inclined toward the return chamber.

[0013] Furthermore, in the above technical solution, each return material unit can be fixed on and penetrate the wall of the combustion chamber; the loosening chamber is arranged on the side close to the combustion chamber, and the upper part is connected to the cyclone separator through the feed pipe, and the cyclone separator is arranged in the combustion chamber.

[0014] Furthermore, in the above technical solution, the return chamber is arranged on a side close to the gasification chamber, and is connected to the annular space of the gasification chamber through a feed pipe.

[0015] Furthermore, in the above technical solution, the loosening chamber receives bed material particles from the combustion chamber and blocks the gas, and the middle and upper parts of the loosening chamber are separated from the return chamber by a partition; a first air distribution cavity is provided at the lower part of the loosening chamber; and a second air distribution cavity is provided at the lower part of the return chamber.

[0016] Furthermore, in the above technical solution, both the loosening chamber bottom plate and the return chamber bottom plate may be provided with air caps or air holes; the first air distribution air cavity and the second air distribution air cavity may be supplied with air through air pipes extending to the outside of the reaction device. The air pipes may be arranged in a cross shape.

[0017] Furthermore, in the above technical solution, the cross-sectional diameter of the loosening chamber can be set to be 1.1 to 1.5 times the cross-sectional diameter of the return chamber.

[0018] Furthermore, in the above technical solution, the feed port of the biomass raw material can be arranged at the bottom of the material layer of the gasification chamber, above the material layer and / or at the top of the reaction device, and the feeding method can be set to spiral feeding.

[0019] Furthermore, in the above technical solution, an inclined chute structure for prolonging the residence time of bed material particles at the bottom and for gas sealing may be provided at the conical surface of the gasification chamber.

[0020] Furthermore, in the above technical solution, the inclined chute structure may specifically include: a first conical surface, which extends obliquely downward from the outer wall surface of the combustion chamber; a second conical surface, which extends obliquely upward from the outer wall surface of the combustion chamber and is enclosed by the first conical surface and the outer wall surface of the combustion chamber to form a relatively closed structure; an inclined chute is formed between the second conical surface and the conical surface at the bottom of the gasification chamber.

[0021] Furthermore, in the above technical solution, the enclosed structure may be an air cavity for introducing secondary air from outside the reaction device.

[0022] Furthermore, in the above technical solution, secondary air holes inclined upward may be provided on the upper part of the air cavity and the wall of the combustion chamber, and the secondary air cooperates with the combustion-supporting air at the bottom of the combustion chamber to extend the residence time of the bed material particles at the bottom.

[0023] Furthermore, in the above technical solution, the pores on the conical surface at the bottom of the vaporization chamber can be arranged so that the pore diameters gradually decrease from bottom to top.

[0024] Furthermore, in the above technical solution, the bed material particles can be inert bed material or metal oxide bed material. The metal oxide bed material can be calcium oxide bed material, which is used to capture carbon dioxide in the gasification chamber to generate calcium carbonate, and the calcium carbonate is decomposed into carbon dioxide by heat in the combustion chamber and discharged with the flue gas.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The present invention adopts an "internal" design, that is, the combustion chamber is arranged inside the gasification chamber to form a jacket structure, which can avoid the feed pipe and the return device in the prior art ("external" design) from being exposed to room temperature, effectively reducing the heat loss of the reaction device, and improving the economic efficiency of the route and the operation cycle of the device;

[0027] 2) The present invention can also effectively improve the heat transfer efficiency through the "built-in" design. The combustion chamber can not only transfer heat through the hot bed material circulation, but also transfer heat to the gasification zone between the outer wall of the combustion chamber and the gasification chamber cylinder through the heat conduction of the wall;

[0028] 3) The multiple return material units of the present invention are evenly arranged along the circumference. When the particle fluidization in different areas of the gasification chamber is abnormal, resulting in abnormal temperature changes in the area, the falling speed can be controlled by giving the return material wind size of the return material units at different positions, so as to achieve the purpose of more uniform and accurate regulation of the gasification zone temperature and thus control the depth of the biomass gasification reaction;

[0029] 4) The present invention fixes the return unit on the wall of the combustion chamber (i.e., in the reaction device) and penetrates the wall of the combustion chamber, and the feed pipe directly leads to the annular gasification zone, thereby avoiding the heat loss and blockage problems caused by the feed pipe being exposed to room temperature in the existing return device;

[0030] 5) The cross-sectional diameter of the loosening chamber of the return material unit of the present invention is designed to be larger than the cross-sectional diameter of the return material chamber, so that the bed material in the loosening chamber is densely transported, which can effectively suppress the backflow of gas and form a material seal; considering that the bottom corners of the loosening chamber are prone to form a fluidized dead zone during dense phase transportation, the loosening chamber bottom plate is tilted to effectively solve the coking problem caused by the fluidized dead zone;

[0031] 6) The cyclone separator of the present invention is also of built-in design, which avoids the cyclone separator being exposed to room temperature and can effectively improve the heat exchange efficiency; the lighter ash particles are entrained out of the reaction device by the air flow and then removed in the tail gas cyclone, so that the reaction device of the present invention does not need to be provided with a separate slag discharge port;

[0032] 7) The inclined chute structure adopted at the bottom of the gasification chamber of the present invention broadens the operating range of the reaction device, so that the reactor can adapt to more complex raw materials and process conditions; at the same time, the inclined chute structure can better achieve the material sealing effect by reducing the diameter of the original particle channel;

[0033] 8) The secondary air distribution setting of the combustion chamber of the present invention can appropriately reduce the combustion-supporting air at the bottom, so that the particles are in a bubbling state at the bottom of the combustion chamber. When the particles bubble and fluidize near the secondary air, they are accelerated by the secondary air that is inclined upward and quickly transported to the return unit. The fast fluidized bed is above the secondary air. This design can increase the residence time of the particles in the high-temperature zone at the bottom, and the tar on its surface can be burned more effectively, which can provide more heat for gasification, reduce the tar content in the flue gas, facilitate the post-treatment of the flue gas, and improve the economic efficiency of the process; when the AER process is applied, it also has the effect of improving the particle regeneration rate, which is more conducive to the capture of carbon dioxide in the gasification chamber, thereby increasing the hydrogen production concentration.

[0034] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the double fluidized bed process flow when calcium oxide is used as bed material particles in the present invention.

[0036] Figure 2 It is a perspective schematic diagram of the built-in heat exchange double fluidized bed reaction device of the present invention.

[0037] Figure 3 It is a schematic internal cross-sectional view of the built-in heat exchange double fluidized bed reaction device of the present invention.

[0038] Figure 4 It is a schematic internal cross-sectional view of the material return unit of the present invention.

[0039] Figure 5 It is a partial schematic diagram of the bottom of the built-in heat exchange double fluidized bed reaction device of the present invention (showing the first embodiment; without secondary air chamber and inclined chute structure).

[0040] Figure 6 It is a partial schematic diagram of the bottom of the built-in heat exchange double fluidized bed reaction device of the present invention (showing the second embodiment; having a secondary air chamber and an inclined chute structure).

[0041] Description of main reference numerals:

[0042] 100-built-in heat exchange double fluidized bed reaction device, 101-product gas outlet;

[0043] 1-gasification chamber, 11-conical surface, 110-air hole, 2-combustion chamber, 21-combustion air inlet, 3-return unit, 30-air pipe, 31-loosening chamber, 310-first air distribution chamber, 311-inclined bottom plate of loosening chamber, 32-return chamber, 320-second air distribution chamber, 33-partition, 34-feeding pipe, 4-cyclone separator, 40-feeding port, 41-feeding pipe, 42-smoke outlet, 5-air chamber, 50-secondary air hole, 51-first conical surface, 52-second conical surface, 53-inclined chute. DETAILED DESCRIPTION

[0044] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0045] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0046] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the figure. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document should be interpreted accordingly.

[0047] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0048] The present invention adopts a dual fluidized bed biomass hydrogen production process (see the process flow chart for details) Figure 1), combined with AER technology, compared with ordinary dual fluidized bed technology, the advantage is that it adds three effects: absorption (Absorb), enhancement (Enhance), and reforming (Reform). While water vapor serves as the gasification air, it is also responsible for reforming the tar produced by gasification to reduce the tar content in the product gas; and the bed material not only serves as a heat carrier, but also has the tasks of absorption and enhancement. AER bed materials are mostly metal oxides, which absorb carbon dioxide in the gasification chamber to complete carbonation and release heat, which not only reduces the carbon dioxide content in the product gas and improves the quality of the product gas, but also provides part of the heat for the gasification reaction, thereby enhancing the biomass gasification process. The carbonated bed material is decomposed by heat in the combustion chamber and releases carbon dioxide. In this way, the carbon dioxide is transported to the flue gas, and the bed material continues to return to the oxide form and enters the gasification chamber to re-capture carbon dioxide.

[0049] The inventors have found through investigation that the dual fluidized bed biomass hydrogen production has the following advantages: the dual fluidized bed reactor decouples combustion and gasification, performs indirect heating, and has a high hydrogen production rate. The hydrogen content in the dry gas at the outlet of the dual fluidized bed reactor can reach more than 50%, and the hydrogen content in the dry gas can reach 78% when combined with the in-situ capture of carbon dioxide. The dual fluidized bed reactor is used, that is, there is only efficient exchange of solids and heat between the combustion chamber and the gasification chamber, which can achieve high heat flux and high processing capacity with a small volume. The tar content in the gas from the dual fluidized bed is 2-10g / m 3 , the tar content is lower than that of the conventional route, which is convenient for subsequent detarring treatment. The built-in dual fluidized bed reaction device of the present invention designs the combustion chamber to be tubular and built into the cylindrical gasification chamber, so as to form an annular space outside the tubular structure as a gasification zone. It avoids the exposed feed pipe and return device caused by "the gasification chamber and the combustion chamber are completely separated" (i.e., external) in the prior art, which can greatly reduce heat loss; it can also effectively avoid the tar adhered to the surface of the low-temperature bed material particles in the prior art becoming more viscous when the temperature is lowered during the process of being transported to the combustion chamber, making it easy for the particles to become compacted and bridged. At the same time, the modification of the bottom of the gasification chamber can maintain a high solid transport rate and give the bed material regeneration time.

[0050] like Figure 2 , 3As shown, the present invention provides a built-in heat exchange double fluidized bed reaction device 100 (with a product gas outlet 101 at the top), which is used in the biomass raw material hydrogen production process. The feed port of the biomass raw material (not shown in the figure) can be arranged at the bottom of the material layer of the gasification chamber 1 of the reaction device 100, above the material layer and / or the top of the reaction device (feeding at different positions according to the type of raw materials and particle density), and the feeding method can be selected as spiral feeding. The built-in heat exchange double fluidized bed reaction device 100 of the present invention comprises at least a gasification chamber 1, a combustion chamber 2 and a return unit 3. Among them, the gasification chamber 1 is a cylindrical structure and has a conical surface 11 at the bottom. The opening on the conical surface 11 is used to pass bubbling fluidizing air (reference Figure 5 The combustion chamber 2 is a tubular structure and is sleeved in the gasification chamber 1. The bottom of the combustion chamber 2 is open and is arranged in the conical area at the bottom of the gasification chamber for introducing vertical upward combustion air (refer to Figure 5 The return material unit 3 is arranged at the upper part of the reaction device 100, and the number of return material units 3 is multiple and evenly arranged along the circumference, and is used to transport the high-temperature bed material particles from the combustion chamber to the annular gasification zone outside the combustion chamber 2 and mix them with the biomass raw materials in the gasification zone to produce hydrogen; the return material unit 3 is provided with a loosening chamber 31 and a return material chamber 32, and the bottom plate 311 of the loosening chamber is inclined toward the return material chamber 32 (refer to Figure 4 ). The present invention places the combustion chamber 2 inside the gasification chamber 1, which can effectively solve the problem of large heat loss and easy blockage of the external feed pipe of the double fluidized bed device, effectively reduce the heat loss, and prevent the particles from blocking the feed pipe due to cooling. The bed material particles can be selected from inert bed materials such as olivine and quartz sand, preferably Figure 1 The calcium oxide particles in the process can be used as bed materials for in-situ capture of carbon dioxide using AER technology. The multiple return material units of the present invention are evenly arranged along the circumference. When the abnormal fluidization of particles in different areas of the gasification chamber causes abnormal changes in regional temperature, the falling speed can be controlled by giving the return material wind size of the return material units at different positions, so as to achieve more uniform and accurate regulation of the gasification zone temperature and thus control the depth of the biomass gasification reaction. The inclined setting of the loosening chamber bottom plate 311 of the return material unit 3 can effectively avoid the problem of fluidization dead zone at the corners of the loosening chamber.

[0051] Specifically, refer to Figure 2 , Figure 3 The "built-in" structure of the present invention adopts a jacket structure, the gasification chamber 1 and the combustion chamber 2 are provided with a vertical upward combustion-supporting air at the bottom of the combustion chamber 2, and the fluidizing air with a vertical cone 11 entering the bottom of the gasification chamber 1 (reference Figure 5). The combustion-supporting air is air, and the fluidizing air is water vapor, both of which can be introduced by means of a hood, wherein the pore size of the hood for fluidizing air gradually decreases from bottom to top (i.e., the fluidization state of the solid particles gradually decreases from bottom to top, which has the effect of sealing the material). The fluidizing air and the combustion-supporting air are reasonably proportioned to ensure that the air does not diffuse into the gasification chamber 1. The combustion chamber 2 is a fast fluidized bed, and the combustion chamber 2 is outside (i.e., the bottom of the gasification chamber 1) is a bubbling fluidized bed, which can provide as much heat as possible to the gasification chamber through the combustion chamber 2 wall and the hot bed material. Further, as Figures 2 to 4 As shown, a cyclone separator 4 can be connected to the upper part of the combustion chamber 2 to separate the flue gas, fly ash and hot bed material. The flue gas, fly ash and hot bed material enter the feed port 40, and the flue gas and fly ash are discharged through the flue gas outlet 42 at the upper part of the cyclone separator, and the bed material particles enter the loosening chamber 31 of the return unit 3 through the lower feed pipe 41. The height of the gasification chamber of the present invention is different from that of the existing biomass double fluidized bed (such as gussing fluidized bed). The combustion chamber 2 can not only transport heat through the hot bed material circulation, but also transfer heat to the gasification zone through the heat conduction of the wall, avoiding the heat loss caused by the external double fluidized bed reactor combustion chamber and the feed pipe exposed to room temperature.

[0052] Further Figure 4 As shown, the specific structure of the return material unit 3 of the present invention is as follows: each return material unit 3 is fixed and penetrates the wall of the combustion chamber 2; the loosening chamber 31 is arranged on the side close to the combustion chamber 2, and the upper part is connected to the cyclone separator 4 through the feed pipe 41, and the cyclone separator 4 is arranged in the combustion chamber 2. The return material chamber 32 is arranged on the side close to the gasification chamber 1, and is connected to the annular space of the gasification chamber 1 through the feed pipe 34. The loosening chamber 31 receives the bed material particles from the combustion chamber 2 and blocks the gas, and the middle and upper parts of the loosening chamber 31 are separated from the return material chamber 32 by a partition 33. A first air distribution chamber 310 is provided at the lower part of the loosening chamber; a second air distribution chamber is provided at the lower part of the return material chamber 32. Wind caps or air holes (not shown in the figure) are provided on the bottom plate of the loosening chamber 31 and the bottom plate of the return material chamber 32. The first air distribution chamber 310 and the second air distribution chamber 320 are supplied with air through the air pipe 30 extending to the outside of the reaction device. By passing an external air source into the first air distribution chamber 310 and the second air distribution chamber 320, bubbles are formed in the lower part of the loosening chamber and the return chamber, and the bed material particles are transported to the feeding pipe 34 and then flow into the gasification chamber 1. Preferably, but not restrictively, the air pipes 30 are arranged in a cross shape (refer to Figure 2 ), making the circumferential wind distribution more uniform.

[0053] The existing return material loosening chamber and return material chamber are usually designed to be relatively small, consistent with the diameter of the material leg part, so as to facilitate the rapid circulation of the bed material. The bed material is generally transported in the loosening chamber of the return material. The inventor has found through research that this existing return material is used for air gasification of biomass in a circulating fluidized bed reactor. Since the hydrogen concentration of the synthesis gas produced by air gasification is relatively low, it can undertake the functions of bed material transportation and preventing gas blowby. However, the hydrogen concentration produced by the double fluidized bed reactor used for biomass hydrogen production is relatively high. As mentioned above, it can generally reach 50%VOL-78%VOL. The conventional return material has an unsatisfactory effect in suppressing gas backflow when the bed material is transported in the dilute phase. During dense phase transportation, the bottom corners of the loosening chamber 11 will form a fluidized dead zone, resulting in poor return of the bed material and coke particles due to cooling blockage, affecting the stable operation of the reactor. Based on this, through the improvement of the return material unit of the present invention, the bed material in the loosening chamber 31 of the return material unit 3 is in the form of dense phase accumulation to form a material seal. Furthermore, the cross-sectional diameter of the loosening chamber 31 is designed to be 1.1 to 1.5 times the cross-sectional diameter of the return chamber 32, and the loosening chamber bottom plate 311 is tilted, which can effectively solve the above-mentioned problems in the prior art. In addition, the return unit 3 is entirely arranged on the wall of the combustion chamber 2 (i.e., inside the reaction device), avoiding the heat loss and blockage problems caused by the feed pipe in the existing return device being exposed to room temperature (for specific bed material particle orientation, see Figure 4 The dashed arrows in the figure indicate the direction).

[0054] Further Figure 2-4 As shown, the cyclone separators 4 of the present invention can be set to multiple, preferably the same number as the return unit 3, and arranged in a circumferential direction, so that the fly ash, flue gas and bed material particles can be separated more effectively, and the temperature of the bed material particles can be avoided from being reduced, thereby improving the heat exchange efficiency.

[0055] Further Figure 6 As shown in the aforementioned Figure 5 On the basis of the first embodiment of the bottom of the gasification chamber, an inclined chute structure for extending the residence time of the bed material particles at the bottom and for gas sealing can also be set at the conical surface 11 of the gasification chamber 1 (i.e., the second embodiment of the bottom of the gasification chamber). The inclined chute structure specifically includes a first conical surface 51 and a second conical surface 52. Among them, the first conical surface 51 extends obliquely downward from the outer wall of the combustion chamber 2; the second conical surface 52 extends obliquely upward from the outer wall of the combustion chamber and is enclosed by the first conical surface 51 and the outer wall of the combustion chamber 2 to form a relatively closed structure. In this way, an oblique chute 53 is formed between the second conical surface 52 and the conical surface 11 at the bottom of the gasification chamber 1. The closed structure is an air cavity 5 for introducing secondary air from outside the reaction device. Preferably, but not restrictively, a secondary air hole 50 inclined upward is provided on the upper part of the air cavity 5 and the wall of the combustion chamber 2, and the secondary air cooperates with the combustion-supporting air at the bottom of the combustion chamber 2 to extend the residence time of the bed material particles at the bottom.

[0056] The inclined chute 53 is equivalent to reducing the diameter of the particle running channel, so that the bed material can still maintain the gas seal under high-speed circulation. This design broadens the operating range of the reaction device, allowing the reaction device to adapt to more complex raw materials and process conditions; at the same time, the first cone 51 and the second cone 52 can be used to distribute the secondary air in the combustion chamber 2. In the case of secondary air, the combustion-supporting air at the bottom can be appropriately reduced to make the particles in a bubbling state at the bottom of the combustion chamber 2. When the particles bubble and fluidize to the vicinity of the secondary air, they are accelerated by the inclined upward secondary air and quickly transported to the return unit 3. The fast fluidized bed is above the secondary air. This design can increase the residence time of the particles in the high-temperature zone at the bottom, burn the tar on its surface more effectively, provide more heat for gasification, reduce the tar content in the flue gas, facilitate the post-treatment of the flue gas, and improve the economic efficiency of the process; when the AER process is applied, it also has the effect of improving the particle regeneration rate, which is more conducive to the capture of carbon dioxide in the gasification chamber, thereby increasing the hydrogen production concentration.

[0057] The following is an application of the present invention Figure 3 The biomass hydrogen production process of the reaction device shown is specifically described as follows:

[0058] 1) The biomass enters the gasification chamber 1 filled with hot bed material from the hopper through the feeding screw, and is in a bubbling fluidized state together with the bed material in the gasification chamber 1, absorbs the heat of the bed material, and undergoes a gasification reaction with water vapor to produce hydrogen-rich gas and semi-coke. The semi-coke particles and the cooled bed material particles move downward, while the gas moves upward, and preliminary gas-solid separation is achieved here;

[0059] 2) The hydrogen-rich gas is discharged from the outlet 101 of the gasification chamber 1, and the semi-coke and the cooling bed material are subjected to the conical water vapor (i.e. Figure 5 The fluidizing air (shown in the figure) is loosened and enters the bottom of the combustion chamber. Under the action of the combustion-supporting air (air), it is in a fast fluidized state. Here, the water vapor at the bottom of the gasification chamber plays a barrier role for the hydrogen-rich gas and air and a fluidizing effect on the particles.

[0060] 3) In the combustion chamber 2, the carbon-containing semi-coke particles are ignited in the air, which increases the temperature of the bed particles in the combustion chamber; the ash particles remaining after the semi-coke is burned out, the semi-coke particles that are not completely burned, the bed material, and the fine powder generated by the wear of the bed material enter the cyclone separator 4 from the feed port 40 (refer to Figure 4 ), since the density and particle size of other particles and bed material particles are quite different, they are discharged from the flue gas outlet 42 at the top of the cyclone separator together with the flue gas, and the bed material is discharged from the bottom of the cyclone separator 4 and enters the loosening chamber 31 of the return unit 3 from the feed pipe 41;

[0061] 4) The hot bed material particles form a material seal in the loosening chamber 31 of the return unit, the synthesis gas generated in the gasification chamber 1 is blocked in the return chamber 32 of the return unit 3, and the flue gas is blocked in the loosening chamber 31 by the material seal. The particles are transported to the gasification chamber 1 by the return wind of the return unit, and the rising mixed flow of synthesis gas and fluidizing gas is heated during the falling process to promote further removal of synthesis gas tar and improve the quality of hydrogen-rich synthesis gas. The hot bed material particles continue to fall and mix with the biomass particles to provide heat for the gasification reaction, thus forming a circulation of bed material in the dual fluidized bed system.

[0062] Example 1

[0063] The room temperature biomass raw materials in the hopper are fed into the gasification chamber of the built-in heat exchange double fluidized bed reaction device of the present invention through a screw feeder. The raw materials fall into the dense phase area of ​​the fluidized bed by gravity, mix with the hot inert bed material at a temperature of 1200K, and are swept by 600K fluidizing wind in the lower part of the gasification chamber in a bubbling fluidized state. The fluidizing gas can be nitrogen or water vapor. The biomass particles are heated to produce hydrogen, carbon monoxide, carbon dioxide, mixed hydrogen-rich gas of low-carbon hydrocarbons, tar and other liquids, and solid particles such as semi-coke particles and ash particles. If the gasification gas is water vapor, tar will also undergo a reforming gasification reaction with water vapor, decompose into low-carbon hydrocarbon gases, and be discharged as product gas together with hydrogen-rich gas. The hydrogen yield in the product dry gas can reach 55%. The cooled bed material particles, semi-coke particles and ash particles are loosened by the water vapor introduced into the conical surface at the bottom of the gasification chamber and enter the bottom of the combustion chamber. Under the action of the combustion-supporting wind (air), they are rapidly fluidized. Some semi-coke particles come into contact with the faster-flowing 600K combustion-supporting air in the combustion chamber, and burn to release a large amount of heat, heating the cooled bed material particles. The flue gas generated by the combustion carries the bed material particles, incompletely burned semi-coke particles and ash particles into the cyclone separator. The bed material particles can be separated from the flue gas and other particles more thoroughly. The flue gas and other particles are discharged from the top of the cyclone separator, and the bed material particles are discharged from the bottom of the cyclone separator and fall into the loosening chamber of the return unit. The particles gradually accumulate to form a material seal. The 1200K hot bed material particles are fluidized by the loosening wind (which can be nitrogen or water vapor) of the return unit, and are transported by the return wind (which can be nitrogen or water vapor) and enter the gasification chamber. Under the action of gravity, they fall into the dilute phase area of ​​the fluidized bed, first heating the rising mixed gas flow of synthesis gas and fluidizing gas to promote further removal of tar in the synthesis gas, and then heating the biomass particles falling into the dense phase area of ​​the gasification chamber. In this way, the bed material completes the cycle in the built-in heat exchange double fluidized bed reaction device of the present invention, does not participate in any reaction, and only serves as a heat carrier.

[0064] Example 2

[0065] When combined with AER technology, the role of the bed material is different from that in Example 1. The room temperature biomass raw material in the hopper is fed into the gasification chamber of the built-in heat exchange double fluidized bed reaction device of the present invention through a screw feeder. The raw material falls into the dense phase area of ​​the fluidized bed by gravity, mixes with the hot calcium oxide bed material at a temperature of 1200K, and is swept by 600K fluidizing wind in the lower part of the gasification chamber in a bubbling fluidized state. The fluidizing gas is water vapor, and the biomass particles are heated to produce hydrogen, carbon monoxide, carbon dioxide, a mixed hydrogen-rich gas of low-carbon hydrocarbons, tar and other liquids, and solid particles such as semi-coke particles and ash particles. Carbon dioxide combines with calcium oxide bed material to form calcium carbonate bed material, which releases a certain amount of heat, and supplies part of the gasification reaction energy while capturing carbon dioxide in the gas; tar and water vapor undergo reforming gasification reaction, decompose into low-carbon hydrocarbon gas, and are discharged as product gas together with hydrogen-rich gas. In this way, the hydrogen content in the product dry gas can reach 78%.

[0066] The cooled calcium carbonate bed material particles, semi-coke particles and ash particles are loosened by the water vapor at the bottom cone of the gasification chamber and enter the bottom of the combustion chamber. Under the action of the combustion-supporting wind (air), they are in a fast fluidized state. A part of the semi-coke particles come into contact with the 600K combustion-supporting air with a faster flow rate in the combustion chamber, and a large amount of heat is released during combustion, which heats the cooled calcium carbonate bed material particles. The calcium carbonate bed material is heated, carbon dioxide is removed, and calcium oxide bed material is regenerated, completing the task of "transporting" carbon dioxide from the product gas to the flue gas. The flue gas generated by the combustion carries the bed material particles, the semi-coke particles that are not completely burned, and the ash particles into the cyclone separator. The bed material particles can be separated from the flue gas and other particles more thoroughly. The flue gas and other particles are discharged from the top of the cyclone separator, and the bed material particles are discharged from the bottom of the cyclone separator and fall into the loosening chamber of the return unit. The particles gradually accumulate to form a material seal. The 1200K hot bed material particles are fluidized by the loosening wind (which can be nitrogen or water vapor) of the return unit, and are transported by the return wind (which can be nitrogen or water vapor) and enter the gasification chamber. Under the action of gravity, they fall into the dilute phase area of ​​the fluidized bed, first heating the rising mixed gas flow of synthesis gas and fluidizing gas to promote further removal of tar in the synthesis gas, and then heating the biomass particles falling into the dense phase area of ​​the gasification chamber, and further capturing carbon dioxide to complete carbonation. In this way, the bed material completes the cycle in the built-in heat exchange double fluidized bed reaction device of the present invention, serving as a carrier of heat and carbon dioxide.

[0067] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A built-in heat exchange double fluidized bed reaction device, characterized in that: Used in biomass raw material hydrogen production process, including: The gasification chamber is a cylindrical structure with a conical surface at the bottom, and a hole is opened on the conical surface for introducing bubbling fluidizing air; The combustion chamber is a tubular structure and is sleeved in the gasification chamber. The bottom of the combustion chamber is open and arranged in the conical area for introducing vertically upward combustion-supporting air; A return material unit is arranged at the upper part of the reaction device, and there are multiple units therein that are evenly arranged along the circumference, and is used to transport high-temperature bed material particles from the combustion chamber to the annular gasification zone outside the combustion chamber and mix them with the biomass raw materials in the gasification zone to produce hydrogen; the return material unit is provided with a loosening chamber and a return material chamber, and the bottom plate of the loosening chamber is inclined toward the return material chamber.

2. The built-in heat exchange double fluidized bed reaction device according to claim 1, characterized in that: Each of the return material units is fixed on and penetrates the wall of the combustion chamber; the loosening chamber is arranged on a side close to the combustion chamber, and the upper part is connected to the cyclone separator through a feed pipe, and the cyclone separator is arranged in the combustion chamber.

3. The built-in heat exchange double fluidized bed reaction device according to claim 2, characterized in that: The return chamber is arranged on a side close to the gasification chamber and is communicated with the annular space of the gasification chamber through a feeding pipe.

4. The built-in heat exchange double fluidized bed reaction device according to claim 3, characterized in that: The loosening chamber receives bed material particles from the combustion chamber and blocks the gas. The middle and upper parts of the loosening chamber are separated from the return chamber by a partition. A first air distribution cavity is provided at the lower part of the loosening chamber. A second air distribution cavity is provided at the lower part of the return chamber.

5. The built-in heat exchange double fluidized bed reaction device according to claim 4, characterized in that: The bottom plate of the loosening chamber and the bottom plate of the return chamber are both provided with wind caps or air holes; the first air distribution cavity and the second air distribution cavity are supplied with air through air pipes extending to the outside of the reaction device.

6. The built-in heat exchange double fluidized bed reaction device according to claim 5, characterized in that: The trachea are arranged in a cross shape.

7. The built-in heat exchange double fluidized bed reaction device according to claim 1, characterized in that: The cross-sectional diameter of the loosening chamber is 1.1 to 1.5 times the cross-sectional diameter of the return chamber.

8. The built-in heat exchange double fluidized bed reaction device according to claim 1, characterized in that: The feed inlet of the biomass raw material is arranged at the bottom of the material layer of the gasification chamber, above the material layer and / or the top of the reaction device, and the feeding method is spiral feeding.

9. The built-in heat exchange double fluidized bed reaction device according to claim 1, characterized in that: The conical surface of the gasification chamber is provided with an inclined chute structure for prolonging the residence time of bed material particles at the bottom and for gas sealing.

10. The built-in heat exchange double fluidized bed reaction device according to claim 9, characterized in that: The inclined chute structure specifically comprises: A first conical surface extending obliquely downward from the outer wall of the combustion chamber; The second conical surface extends upward obliquely from the outer wall surface of the combustion chamber and encloses the first conical surface and the outer wall surface of the combustion chamber to form a relatively closed structure; an oblique chute is formed between the second conical surface and the conical surface at the bottom of the gasification chamber.

11. The built-in heat exchange double fluidized bed reaction device according to claim 10, characterized in that: The enclosed structure is an air cavity for introducing secondary air from outside the reaction device.

12. The built-in heat exchange double fluidized bed reaction device according to claim 11, characterized in that: The upper part of the air cavity and the wall of the combustion chamber are provided with secondary air holes inclined upward, and the secondary air cooperates with the combustion-supporting air at the bottom of the combustion chamber to prolong the residence time of the bed material particles at the bottom.

13. The built-in heat exchange double fluidized bed reaction device according to claim 1, characterized in that: The apertures of the pores on the conical surface at the bottom of the gasification chamber gradually decrease from bottom to top.

14. The built-in heat exchange double fluidized bed reaction device according to claim 1, characterized in that: The bed material particles are inert bed material or metal oxide bed material.

15. The built-in heat exchange double fluidized bed reaction device according to claim 14, characterized in that: The metal oxide bed material is a calcium oxide bed material, which is used to capture carbon dioxide in the gasification chamber to generate calcium carbonate. The calcium carbonate is decomposed into carbon dioxide by heat in the combustion chamber and discharged with the flue gas.

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