Built-in heat exchange double fluidized bed reaction device

Abstract

The application discloses a built-in heat exchange double fluidized bed reaction device, which is used for hydrogen production from biomass raw materials and comprises a gasification chamber, a combustion chamber and a return material unit. The gasification chamber is in a cylindrical structure and is provided with a conical surface at the bottom. The conical surface is provided with a hole for passing in bubbling fluidization wind. The combustion chamber is in a tubular structure and is sleeved in the gasification chamber. The bottom of the combustion chamber is in an open state and is arranged in the conical surface area for passing in vertical upward combustion-supporting wind. The return material unit is arranged at the upper part of the reaction device, is multiple in number and is uniformly arranged in the circumferential direction. The return material unit is used for carrying high-temperature bed material particles from the combustion chamber to the annular gasification area outside the combustion chamber and mixing the bed material particles with biomass raw materials in the gasification area for hydrogen production. The return material unit is provided with a loosening chamber and a return material chamber. The bottom plate of the loosening chamber is arranged in an inclined manner towards the return material chamber. The built-in design of the double fluidized bed avoids exposure of the feeding pipe and the return material device to room temperature, reduces heat loss of the reactor and gives enough regeneration time to the bed material under the condition of keeping a high solid conveying rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen production from biomass, and particularly relates to an internal heat exchange double fluidized bed reaction device. BACKGROUND

[0002] As a kind of efficient clean energy, hydrogen energy is developing at the right moment. Among various technical routes for hydrogen production from biomass, the use of fluidized bed reactors for efficient thermal conversion to produce hydrogen-rich gas has a promising prospect.

[0003] There are existing applications of double fluidized beds in the prior art. The double fluidized bed reactor has the following advantages: it decouples combustion and gasification, indirect heating, and high hydrogen production rate; 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; and the tar content is lower than that of conventional routes, facilitating subsequent tar removal treatment.

[0004] Chinese Patent Application CN109704278A discloses a device and method for preparing hydrogen gas by double fluidized bed biomass pyrolysis gasification. 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 pipe, and the rear end of the pyrolysis furnace riser pipe is connected with a pyrolysis furnace cyclone separator. The upper part of the pyrolysis furnace cyclone separator is connected with a shift reactor, and the lower part is connected with a pyrolysis furnace return valve. The other outlet of the pyrolysis furnace return valve is connected with the fluidized bed combustion furnace. The fluidized bed combustion furnace includes a combustion furnace riser pipe. The other outlet of the pyrolysis furnace return valve is connected with the bottom of the combustion furnace riser pipe. An oxygen carrier cyclone separator is arranged in the middle of the combustion furnace riser pipe, and a CO2absorbent cyclone separator is arranged at the top. In the preparation process of this scheme, pure oxygen is not needed as a gasification agent. The system only needs to supplement air as a gasification agent to meet the production demand, and the production cost is low. Moreover, the pyrolysis furnace does not use air for fluidization, and the effective component content in the biomass gas is high.

[0005] The existing double fluidized bed separates the gasification chamber and the combustion chamber, uses a feeding pipe and a return valve for heat and bed material exchange, and produces a certain amount of heat loss during transportation between the two fluidized beds. The biomass raw material, which already has a low calorific value, cannot be self-heated by the combustion of residual carbon to supply the gasification reaction, and additional fuel needs to be added in the combustion chamber. This reduces the economy. In addition, the low-temperature bed particles stick together and form bridges during transportation to the combustion chamber, which blocks the reactor feeding pipe and affects the circulation of the reactor, restricting the operation cycle of the device.

[0006] In addition, since the AER bed material (AER technology compared with ordinary double fluidized bed technology, adding three effects of absorption (Absorb), enhance (Enhance), reform (Reform)) regeneration needs a certain time, and the existing double fluidized bed device combustion chamber is mostly fast fluidized bed, so although a higher solid conveying rate can be maintained, the bed material regeneration time is short.

[0007] In addition, the existing double fluidized bed application returns the material, the volume of the loosening chamber is small, and the corners are easy to appear fluidized dead zone. In the process of hydrogen production from biomass, the coke particles in the solid particles in the return material and the biomass particles are easy to form hardening, causing coking.

[0008] Therefore, an internal heat exchange double fluidized bed reaction device is needed to avoid the use of external feeding pipe, avoid the exposure of feeding pipe and return material to room temperature, reduce the heat loss of the reactor, improve the economy of the route and the operation cycle of the device, maintain a higher solid conveying rate, and give the bed material enough regeneration time.

[0009] The information disclosed in this part of the background is only intended to increase the understanding of the overall background of the present application, and should not be considered as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0010] The purpose of the present application is to provide an internal heat exchange double fluidized bed reaction device, which changes the external double fluidized bed to internal, avoids the exposure of feeding pipe and return material to room temperature, and reduces the heat loss of the reactor. At the same time, the device can give the bed material enough regeneration time while maintaining a higher solid conveying rate.

[0011] Another purpose of the present application is to provide an internal heat exchange double fluidized bed reaction device, which can effectively avoid the fluidized dead zone of the loosening chamber in the return material unit.

[0012] To achieve the above purpose, the present application provides an internal heat exchange double fluidized bed reaction device for hydrogen production process of biomass raw material, which comprises: a gasification chamber which is a cylindrical structure and is provided with a conical surface at the bottom, and a hole is opened on the conical surface for passing in bubbling fluidization wind; a combustion chamber which is a tubular structure and is sleeved in the gasification chamber, the bottom of the combustion chamber is in an open state and is arranged in the conical surface area for passing in vertical upward combustion supporting wind; a return material unit which is arranged at the upper part of the reaction device and is multiple in number and uniformly arranged in the circumferential direction, for carrying high temperature bed material particles from the combustion chamber to the annular gasification area outside the combustion chamber and mixing with the biomass raw material in the gasification area for hydrogen production; the return material unit is provided with a loosening chamber and a return chamber, and the bottom plate of the loosening chamber is inclinedly arranged towards the return chamber.

[0013] Further, in the above technical solution, each return material unit can be fixed and penetrated on the wall surface of the combustion chamber; the loosening chamber is arranged on the side close to the combustion chamber, and the upper portion is communicated with the cyclone separator through the feeding pipe; and the cyclone separator is arranged in the combustion chamber.

[0014] Further, in the above technical solution, the return material chamber is arranged on the side close to the gasification chamber, and is communicated with the annular space of the gasification chamber through the feeding pipe.

[0015] Further, in the above technical solution, the loosening chamber receives the bed material particles from the combustion chamber and blocks the gas, the middle and upper portions of the loosening chamber are separated from the return material chamber through the partition plate; the lower portion of the loosening chamber is provided with the first air distribution wind cavity; and the lower portion of the return material chamber is provided with the second air distribution wind cavity.

[0016] Further, in the above technical solution, the air caps or air holes can be arranged on the bottom plates of the loosening chamber and the return material chamber; the first air distribution wind cavity and the second air distribution wind cavity can be supplied with air through the air pipes extending to the outside of the reaction device. The air pipes can be arranged in a cross shape.

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

[0018] Further, in the above technical solution, the feeding 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 mode can be set to be screw feeding.

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

[0020] Further, in the above technical solution, the chute structure can specifically include: a first conical surface extending downwardly and obliquely from the outer wall surface of the combustion chamber; and a second conical surface extending upwardly and obliquely from the outer wall surface of the combustion chamber and surrounding the first conical surface and the outer wall surface of the combustion chamber to form a relatively closed structure; and the chute is formed between the second conical surface and the conical surface of the bottom of the gasification chamber.

[0021] Further, in the above technical solution, the closed structure can be a wind cavity for introducing the secondary air from the outside of the reaction device.

[0022] Further, in the above technical solution, the upper portion of the wind cavity and the wall surface of the combustion chamber can be provided with the upwardly inclined secondary air holes, 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.

[0023] Further, in the above technical solution, the air holes on the conical surface of the bottom of the gasification chamber can be arranged to gradually decrease in diameter from bottom to top.

[0024] Further, in the technical scheme, 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 by heat in the combustion chamber to generate carbon dioxide and is discharged with flue gas.

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

[0026] 1) The present application adopts an "inbuilt" design, i.e., the combustion chamber is arranged inside the gasification chamber to form a jacket structure, which can avoid the feeding pipe and the material return device in the prior art ("outbuilt" design) from being exposed to room temperature, effectively reduces the heat loss of the reaction device, and improves the economic efficiency of the route and the operation cycle of the device.

[0027] 2) The "inbuilt" design of the present application can also effectively improve the heat transfer efficiency. The combustion chamber can not only transfer heat through the circulating bed material, but also transfer heat to the gasification zone between the outer wall of the combustion chamber and the cylinder of the gasification chamber through the heat conduction of the device wall.

[0028] 3) The plurality of material return units of the present application are uniformly arranged in the circumferential direction. When the temperature in the different regions of the gasification chamber changes abnormally due to abnormal fluidization of the particles in the regions, the material falling speed can be controlled by controlling the size of the material return air of the material return units at different positions, so as to more uniformly and accurately control the temperature of the gasification zone and control the depth of the biomass gasification reaction.

[0029] 4) The material return unit of the present application is fixed on the device wall of the combustion chamber (i.e., in the reaction device) and penetrates the device wall of the combustion chamber. The feeding pipe directly enters the annular gasification zone, which avoids the heat loss and blockage caused by the exposure of the feeding pipe in the prior art material return device to room temperature.

[0030] 5) The cross-sectional size of the loosening chamber of the material return unit of the present application is designed to be larger than that of the material return chamber, so that the bed material in the loosening chamber is in dense phase conveying, which can effectively inhibit the backflow of gas and form a seal. Considering that the bottom corners of the loosening chamber are prone to form a fluidized dead zone during dense phase conveying, the bottom plate of the loosening chamber is arranged in an inclined manner, which can effectively solve the coking problem caused by the fluidized dead zone.

[0031] 6) The cyclone separator of the present application is also an "inbuilt" design, which avoids the exposure of the cyclone separator to room temperature and can effectively improve the heat transfer efficiency. The lighter ash particles are carried out of the reaction device by the gas flow, and then removed in the tail gas cyclone, so that the reaction device of the present application does not need to be provided with a separate slag discharge port.

[0032] 7) The inclined chute structure used at the bottom of the gasification chamber of the present application widens the operation 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 realize the effect of seal because it reduces the size of the original particle passage.

[0033] 8) The combustion chamber secondary air distribution arrangement, the combustion-supporting air at the bottom can be appropriately reduced, so that the particles are in a bubbling state at the bottom of the combustion chamber, and when the particle bubbling fluidization approaches the secondary air, it is accelerated by the inclined upward secondary air and is quickly transported to the return material unit. The upper part of the secondary air is a fast fluidized bed. Through this design, the residence time of particles in the high-temperature zone at the bottom can be increased, and the tar on the surface can be more effectively burned, which can provide more heat for gasification, reduce the tar content in the flue gas, facilitate the post-processing of the flue gas, and improve the economic efficiency of the process; when the AER process is applied, the particle regeneration rate is also improved, 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 a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application and can be implemented according to the content of the specification, at the same time, in order to make the above and other purposes, technical features and advantages of the present application more easily understood, one or more preferred embodiments are listed below, and the details are described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

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

[0036] Figure 2 is a perspective view of the built-in heat exchange double fluidized bed reaction device of the present application.

[0037] Figure 3 is a perspective view of the built-in heat exchange double fluidized bed reaction device of the present application.

[0038] Figure 4 is a perspective view of the built-in heat exchange double fluidized bed reaction device of the present application.

[0039] Figure 5 is a perspective view of the built-in heat exchange double fluidized bed reaction device of the present application.

[0040] Figure 6 is a perspective view of the built-in heat exchange double fluidized bed reaction device of the present application.

[0041] 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-gas hole, 2-combustion chamber, 21-combustion air inlet, 3-return material unit, 30-air pipe, 31-loosening chamber, 310-first air distribution cavity, 311-loosening chamber inclined bottom plate, 32-return material chamber, 320-second air distribution cavity, 33-baffle, 34-feeding pipe, 4-cyclone separator, 40-feeding inlet, 41-feeding pipe, 42-flue gas outlet, 5-air cavity, 50-secondary air hole, 51-first conical surface, 52-second conical surface, 53-inclined chute. DETAILED DESCRIPTION

[0044] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of the present application is not limited by the specific embodiments.

[0045] Unless otherwise clearly indicated, throughout the description and the claims, the term "comprise" or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated element or group of elements but not the exclusion of any other element or group of elements.

[0046] In this document, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein interpreted accordingly.

[0047] In this document, the terms "first", "second", etc. are used to distinguish between two different elements or components, and are not used to define a particular position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can be interchanged with each other.

[0048] The present application adopts a double fluidized bed to carry out a biomass hydrogen production process (see process flow chart Figure 1), combined with AER technology, compared with ordinary double fluidized bed technology, the advantage is to add three effects of absorption (Absorb), enhancement (Enhance), and reforming (Reform). Water vapor is responsible for reforming the tar generated by gasification as gasification wind, so as to reduce the content of tar in product gas; and the bed material not only plays the role of heat carrier, but also undertakes the task of absorption and enhancement. AER bed material is mostly metal oxide, which absorbs carbon dioxide in the gasification chamber to complete carbonation and release heat, not only reducing the content of carbon dioxide in product gas and improving the quality of product gas, but also providing part of the heat for the gasification reaction and enhancing the biomass gasification process. The carbonated bed material is decomposed in the combustion chamber to release carbon dioxide, so that the carbon dioxide is transported to the flue gas, and the bed material returns to the oxide form and enters the gasification chamber to recapture carbon dioxide.

[0049] The inventor found through research that the double fluidized bed for hydrogen production from biomass has the following advantages: the double fluidized bed reactor decouples combustion and gasification, indirect heating, and high hydrogen production rate. The hydrogen content in the dry gas at the outlet of the double fluidized bed reactor can reach more than 50%, and the hydrogen content in the dry gas can reach 78% combined with the method of in-situ carbon dioxide capture; the double fluidized bed reactor, i.e. only solid and heat exchange between the combustion chamber and the gasification chamber, can achieve high heat flux and high processing capacity with small volume; the tar content in the double fluidized bed gas is 2-10 g / m 3 , which is lower than that of conventional routes, facilitating subsequent tar removal treatment. The built-in double fluidized bed reaction device of the present application forms an annular space outside the tubular structure as a gasification zone by designing the combustion chamber as a tube and placing it inside the cylindrical gasification chamber. This avoids the exposed feeding pipe and returner caused by the complete separation of the gasification chamber and the combustion chamber in the prior art (i.e. external type), which can greatly reduce heat loss; it can also effectively avoid the phenomenon of particle bonding, bridging, etc. between particles caused by the increase in adhesion of the tar on the surface of the low-temperature bed material particles during the transportation process to the combustion chamber. At the same time, the modification of the bottom of the gasification chamber can not only maintain a high solid conveying rate, but also give the bed material regeneration time.

[0050] As Figure 2 , 3As shown, this invention provides a built-in heat exchange dual fluidized bed reactor 100 (with a product gas outlet 101 at the top) for hydrogen production from biomass feedstock. The biomass feedstock inlet (not shown in the figure) can be located at the bottom of the feed layer, above the feed layer, and / or at the top of the reactor in the gasification chamber 1 of the reactor 100 (feeding at different locations depending on the type and particle density of the feedstock). The feeding method can be a spiral feed. The built-in heat exchange dual fluidized bed reactor 100 of this invention includes at least a gasification chamber 1, a combustion chamber 2, and a return unit 3. The gasification chamber 1 has a cylindrical structure and a conical surface 11 at the bottom. The conical surface 11 has openings for introducing bubbling fluidizing air (see reference). Figure 5 Combustion chamber 2 is a tubular structure housed within gasification chamber 1. The bottom of combustion chamber 2 is open and located within the conical region at the bottom of the gasification chamber, used to introduce vertically upward combustion air (see reference). Figure 5 The combustion air inlet 21 is located in the upper part of the reaction device 100. Multiple return units 3 are arranged circumferentially and are used to transport the high-temperature bed material particles from the combustion chamber to the annular gasification zone outside the combustion chamber 2, where they are mixed with the biomass feedstock in the gasification zone to produce hydrogen. The return unit 3 has a loosening chamber 31 and a return chamber 32. The bottom plate 311 of the loosening chamber is inclined towards the return chamber 32 (see reference). Figure 4 This invention integrates the combustion chamber 2 within the gasification chamber 1, effectively solving the problems of high heat loss and easy clogging of the external feed pipe in a dual fluidized bed device. It effectively reduces heat loss and prevents particles from clogging the feed pipe due to cooling. The bed material particles can be inert materials such as olivine or quartz sand, with olivine being the preferred material. Figure 1 The calcium oxide particles and other materials used in the process can be used as bed materials for in-situ carbon dioxide capture using AER technology. In this invention, multiple return units are uniformly arranged circumferentially. When abnormal particle fluidization occurs in different areas of the gasification chamber, leading to abnormal temperature changes, the material drop speed can be controlled by adjusting the return air volume of the return units at different locations. This achieves more uniform and precise temperature control in the gasification zone, thereby controlling the depth of the biomass gasification reaction. The inclined bottom plate 311 of the loosening chamber of the return unit 3 effectively avoids the problem of fluidization dead zones at the corners of the loosening chamber.

[0051] Specifically, further reference Figure 2 , Figure 3 The "built-in" structural design of this invention features a jacketed structure for the gasification chamber 1 and the combustion chamber 2. The combustion chamber 2 has a vertically upward-facing combustion air supply at its bottom, while the gasification chamber 1 has a fluidizing air supply via a vertical conical inlet 11 at its bottom (see reference). Figure 5Combustion air is air, and fluidizing air is water vapor; both can be introduced via air caps. The pore size of the fluidizing air caps gradually decreases from bottom to top (i.e., the fluidization state of the solid particles gradually decreases from bottom to top, acting as a material seal). The ratio of fluidizing air to combustion air is optimized to ensure that air does not diffuse into gasification chamber 1. Combustion chamber 2 contains a rapid fluidized bed, while the area outside combustion chamber 2 (i.e., the bottom of gasification chamber 1) is a bubbling fluidized bed. The combustion chamber 2 walls and the heated bed material provide as much heat as possible to the gasification chamber. Further details are as follows... Figures 2 to 4 As shown, a cyclone separator 4 can be connected to the upper part of the combustion chamber 2 to separate flue gas, fly ash, and hot bed material. Flue gas, fly ash, and hot bed material enter the feed inlet 40. Flue gas and fly ash are discharged through the flue gas outlet 42 at the top of the cyclone separator, while bed material particles enter the loosening chamber 31 of the return unit 3 through the feed pipe 41 at the bottom. The height of the gasification chamber in this invention differs from that of existing biomass dual fluidized beds (such as gussing fluidized beds). The combustion chamber 2 can not only transfer heat through the circulation of hot bed material, but also transfer heat to the gasification zone through heat conduction through the reactor wall, avoiding heat loss caused by the external dual fluidized bed reactor combustion chamber and feed pipe being exposed to room temperature.

[0052] Further as 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 located near the combustion chamber 2, and its upper part is connected to the cyclone separator 4 through the feed pipe 41, and the cyclone separator 4 is located inside the combustion chamber 2. The return material chamber 32 is located near 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. The middle and upper parts of the loosening chamber 31 are separated from the return material chamber 32 by the partition plate 33. The lower part of the loosening chamber is provided with a first air distribution chamber 310; the lower part of the return material chamber 32 is provided with a second air distribution chamber. The bottom plate of the loosening chamber 31 and the bottom plate of the return material chamber 32 are both provided with air caps or air holes (not shown in the figure). The first air distribution chamber 310 and the second air distribution chamber 320 are supplied with gas through the air pipe 30 extending to the outside of the reaction device. By introducing external air 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 limitingly, the air pipes 30 are arranged in a cross shape (see reference). Figure 2 This makes the circumferential air distribution more uniform.

[0053] The existing return feeder loosening chamber and return chamber are usually designed to be small and consistent with the diameter of the material leg part, so as to facilitate the rapid circulation of the bed material, and the bed material is generally transported in the dilute phase in the return feeder loosening chamber. The inventor has found through research that the existing return feeder is used for the air gasification of biomass in a circulating fluidized bed reactor, and the hydrogen gas concentration of the synthesis gas generated by air gasification is low, so the return feeder can bear the function of bed material transportation and prevent gas backflow. However, the hydrogen gas concentration generated by the dual fluidized bed reactor for hydrogen production from biomass is high, and as described above, it can generally reach 50% VOL-78% VOL. The inhibitory effect of the conventional return feeder on gas backflow is not ideal when the bed material is transported in the dilute phase, and a fluidized dead zone is formed at the bottom corner of the loosening chamber 11 when the bed material is transported in the dense phase, which leads to the blockage of the return material due to the cooling of the bed material and coke particles, and affects the stable operation of the reactor. Based on this, through the improvement of the return material unit of the present application, the bed material is in the form of dense phase accumulation to form a material seal in the loosening chamber 31 of the return material unit 3. Further, the present application designs the cross-sectional size of the loosening chamber 31 to be 1.1 to 1.5 times the cross-sectional size of the return chamber 32, and the bottom plate 311 of the loosening chamber is inclined, which can effectively solve the above-mentioned problems in the prior art. In addition, the overall return material unit 3 is arranged on the wall of the combustion chamber 2 (i.e. inside the reaction device), which avoids the heat loss and blockage problem caused by the exposure of the feeding pipe in the existing return material device to room temperature (for the specific bed material particle direction, see the dotted arrow in Figure 4 .

[0054] Further as shown in Figures 2-4 , the cyclone separator 4 of the present application can be arranged in multiple, preferably the same number as the return material unit 3, and arranged in a circumferential direction, which can more effectively separate fly ash, flue gas and bed material particles, and avoid the temperature reduction of the bed material particles, thereby improving the heat exchange efficiency.

[0055] Further as shown in Figure 6 , based on the first embodiment of the bottom of the gasification chamber described above Figure 5 , a chute structure for prolonging the residence time of the bed material particles at the bottom and for gas sealing can also be arranged at the taper 11 of the gasification chamber 1 (i.e. the second embodiment of the bottom of the gasification chamber). The chute structure specifically includes a first taper 51 and a second taper 52. The first taper 51 extends downwardly and obliquely from the outer wall surface of the combustion chamber 2; the second taper 52 extends upwardly and obliquely from the outer wall surface of the combustion chamber and is enclosed with the first taper 51 and the outer wall surface of the combustion chamber 2 to form a relatively closed structure. In this way, the second taper 52 and the taper 11 at the bottom of the gasification chamber 1 form a chute 53. The closed structure is an air cavity 5 for introducing secondary air from the outside of the reaction device. Preferably but not limitedly, an inclined upward secondary air hole 50 is arranged on the upper part of the air cavity 5 and the wall surface of the combustion chamber 2, and the secondary air cooperates with the combustion-supporting air at the bottom of the combustion chamber 2 to prolong the residence time of the bed material particles at the bottom.

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

[0057] The biomass hydrogen production process using the reaction device shown in the present application is described in detail as follows: Figure 3 The biomass hydrogen production process using the reaction device shown in the present application is described in detail 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 fluidization state with the bed material in the gasification chamber 1, absorbs the heat of the bed material, and undergoes a gasification reaction with steam to produce hydrogen-rich gas and semicoke. The semicoke particles and the cooled bed material particles move downward, while the gas moves upward, achieving preliminary gas-solid separation here;

[0059] 2) The hydrogen-rich gas is discharged from the outlet 101 of the gasification chamber 1, and the semicoke and cooled bed material are loosened by the tapered steam (i.e. fluidization air) and enter the bottom of the combustion chamber to be in a fast fluidization state under the action of combustion-supporting air (air). The steam at the bottom of the gasification chamber plays a blocking role for the hydrogen-rich gas and air and a fluidization role for the particles; Figure 5

[0060] 3) In the combustion chamber 2, the carbon-containing semicoke particles are ignited in the air, which raises the temperature of the bed material particles in the combustion chamber; after the semicoke is burned out, the remaining ash particles, semicoke particles that are not completely burned, bed material, and fine powder generated by the abrasion of the bed material enter the cyclone separator 4 from the feed inlet 40 (refer to Figure 4 ). Due to the large difference in density and particle size between other particles and bed material particles, they are discharged from the flue gas outlet 42 at the top of the cyclone separator, and the bed material is discharged from the lower part of the cyclone separator 4 and enters the loosening chamber 31 of the return material unit 3 from the feed pipe 41;

[0061] ​4) The hot bed material particles form a 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 seal, the particles are carried by the return air of the return unit into the gasification chamber 1, and in the process of falling, the rising synthesis gas is mixed with the fluidizing gas, which promotes the further removal of the synthesis gas tar, improves the quality of the hydrogen-rich synthesis gas, and 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 the bed material in the double fluidized bed system.

[0062] Example 1

[0063] The normal temperature biomass raw material in the hopper is sent into the gasification chamber of the built-in heat exchange double fluidized bed reaction device of the present application by the screw feeder, the raw material falls to the dense phase zone of the fluidized bed by gravity and mixes with the hot inert bed material with a temperature of 1200K, is blown by the 600K fluidizing air in the bubbling fluidization state at the lower part of the gasification chamber, the fluidizing gas can be nitrogen or steam, the biomass particles generate hydrogen, carbon monoxide, carbon dioxide, low-carbon hydrocarbon mixed hydrogen-rich gas, tar and other liquids, and semi-coke particles and ash particles and other solid particles by heating. If the gasification gas is steam, the tar will also undergo a reforming gasification reaction with the steam to decompose into low-carbon hydrocarbon gas, which is discharged together with the hydrogen-rich gas as product gas, and the hydrogen yield in the product dry gas can reach 55%. The cooled bed material particles and semi-coke particles and ash particles are loosened by the steam introduced through the conical surface at the bottom of the gasification chamber and enter the bottom of the combustion chamber, which is in a fast fluidization state under the action of the combustion air (air), a part of the semi-coke particles contact the 600K combustion air with a faster flow rate in the combustion chamber, burn and release a large amount of heat to heat the cooled bed material particles, and the flue gas generated by the combustion carries the bed material particles, semi-coke particles and ash particles that are not completely burned into the cyclone separator. The bed material particles can be more thoroughly separated from the flue gas and other particles, the flue gas and other particles are discharged from the top end 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 seal, the hot bed material particles at 1200K are fluidized by the loosening air (which can be nitrogen or steam) of the return unit, are carried by the return air (which can be nitrogen or steam) into the gasification chamber, and fall into the dilute phase zone of the fluidized bed under the action of gravity, first heat the rising synthesis gas mixed with the fluidizing gas to promote the further removal of the tar in the synthesis gas, and then heat the biomass particles falling into the dense phase zone of the gasification chamber. In this way, the bed material completes the circulation in the built-in heat exchange double fluidized bed reaction device of the present application, does not participate in any reaction, and only serves as a heat carrier.

[0064] Example 2

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

[0066] The cooled calcium carbonate bed material particles and semi-coke particles and ash particles are loosened by water vapor at the conical surface at the bottom of the gasification chamber, enter the bottom of the combustion chamber, and are in a fast fluidization state under the action of the combustion air (air). A part of the semi-coke particles contact the 600K combustion air with a faster flow rate in the combustion chamber, burn to release a large amount of heat, heat the cooled calcium carbonate bed material particles, and the calcium carbonate bed material is heated to remove carbon dioxide and regenerate calcium oxide bed material, completing the task of "transporting" carbon dioxide from the product gas to the flue gas. The flue gas produced by combustion carries the bed material particles, semi-coke particles that are not completely burned, and ash particles into the cyclone separator. The bed material particles can be more thoroughly separated from the flue gas and other particles, 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 material unit, the particles gradually accumulate to form a seal, the hot bed material particles at 1200K are fluidized by the return material loosening wind (which can be nitrogen or water vapor), are transported by the return material wind (which can be nitrogen or water vapor), enter the gasification chamber, and fall into the fluidized bed dilute phase zone under the action of gravity. First, heat the rising synthesis gas and fluidizing gas mixture to promote further removal of tar in the synthesis gas, and then heat the biomass particles falling into the dense phase zone of the gasification chamber and further capture carbon dioxide to complete carbonation. In this way, the bed material completes a cycle in the built-in heat exchange double fluidized bed reaction device of the application and serves as a carrier for heat and carbon dioxide.

[0067] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and various modifications and variations are possible in light of the above teachings. It is intended that the embodiments be limited only by the claims. A variety of changes and modifications can be suggested by the above description, and it is intended that the application encompass such changes and modifications as fall within the scope of the claims. Any simple modifications, equivalent changes, and modifications based on the above-described exemplary embodiments should fall within the protection scope of the application.

Claims

1. An internally heat-exchanging dual fluidized bed reactor apparatus, characterized by, A hydrogen production process for biomass raw material, comprising: a gasification chamber, which is a cylindrical structure and is provided with a conical surface at the bottom, and a hole is opened on the conical surface for passing in the bubbling fluidization wind; a combustion chamber, which is a tubular structure and is sleeved in the gasification chamber, the bottom of the combustion chamber is in an open state and is arranged in the conical surface area for passing in the vertical upward combustion-supporting wind; a return material unit, which is arranged at the upper part of the reaction device and is multiple in number and is uniformly arranged in the circumferential direction, for carrying the high-temperature bed material particles from the combustion chamber to the annular gasification area outside the combustion chamber and mixing with the biomass raw material in the gasification area for hydrogen production; the return material unit is provided with a loosening chamber and a return material chamber, and the bottom plate of the loosening chamber is arranged obliquely towards the return material chamber; each return material unit is fixed and penetrates the wall surface of the combustion chamber; the loosening chamber is arranged close to the combustion chamber and the upper part is communicated with a cyclone separator through a feeding pipe, and the cyclone separator is arranged in the combustion chamber.

2. The built-in heat exchange double fluidized bed reactor apparatus according to claim 1, wherein The return material chamber is arranged close to the gasification chamber and is communicated with the annular space of the gasification chamber through a feeding pipe.

3. The built-in heat exchange double fluidized bed reactor apparatus according to claim 2, wherein The loosening chamber receives the 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 material chamber by a partition; the lower part of the loosening chamber is provided with a first air distribution wind cavity; and the lower part of the return material chamber is provided with a second air distribution wind cavity.

4. The built-in heat exchange double fluidized bed reactor apparatus according to claim 3, wherein Air caps or air holes are arranged on the bottom plates of the loosening chamber and the return material chamber; and the first air distribution wind cavity and the second air distribution wind cavity are supplied with air through air pipes extending to the outside of the reaction device.

5. The built-in heat exchange double fluidized bed reactor apparatus according to claim 4, wherein The air pipes are arranged in a cross shape.

6. The built-in heat exchange double fluidized bed reactor apparatus according to claim 1, wherein The cross-sectional dimension of the loosening chamber is 1.1 to 1.5 times that of the return material chamber.

7. The built-in heat exchange double fluidized bed reactor apparatus according to claim 1, wherein The feeding port of the biomass raw material is 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 mode is screw feeding.

8. The built-in heat exchange double fluidized bed reactor apparatus according to claim 1, wherein The conical surface of the gasification chamber is provided with a chute structure for prolonging the residence time of the bed material particles at the bottom and for gas sealing.

9. The internal heat exchange double fluidized bed reactor apparatus according to claim 8, wherein The chute structure specifically comprises: 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 forms a relatively closed structure with the first conical surface and the outer wall surface of the combustion chamber; and a chute is formed between the second conical surface and the conical surface of the bottom of the gasification chamber.

10. The internal heat exchange double fluidized bed reactor apparatus according to claim 9, wherein The closed structure is an air cavity for passing in the secondary wind from the outside of the reaction device.

11. The internal heat exchange double fluidized bed reactor apparatus according to claim 10, wherein An obliquely upward secondary wind air hole is arranged on the upper part of the air cavity and the wall surface of the combustion chamber, and the secondary wind cooperates with the combustion-supporting wind at the bottom of the combustion chamber for prolonging the residence time of the bed material particles at the bottom.

12. The internal heat exchange double fluidized bed reactor apparatus according to claim 1, wherein The air holes on the conical surface of the bottom of the gasification chamber gradually decrease in size from bottom to top.

13. The built-in heat exchange double fluidized bed reactor apparatus according to claim 1, wherein The bed material particles are inert bed material or metal oxide bed material.

14. The internal heat exchange double fluidized bed reactor apparatus according to claim 13, wherein The metal oxide bed material adopts calcium oxide bed material for capturing carbon dioxide in the gasification chamber to generate calcium carbonate, and the calcium carbonate is decomposed by heat in the combustion chamber to generate carbon dioxide and is discharged with the flue gas.

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