Multi-section tandem fluidized bed reaction system and use method thereof

Abstract

The invention relates to a multi-section tandem fluidized bed reaction system in the technical field of gas-solid fluidized beds. The multi-section tandem fluidized bed reaction system comprises a gas-solid separation area, a multi-section tandem reaction area and a solid material receiving and circulating area which are sequentially communicated from top to bottom, a reactor and a stocker which are connected from top to bottom are arranged in a segmented reaction area of the multi-segment tandem reaction area, a distributor is arranged in an inner cavity of the reactor, a material disperser is arranged at the bottom of the reactor, a coated raw material feeding line is connected to the side wall of the distributor, and a loose air feeding line is connected to the bottom of the stocker; according to the invention, the problems of short retention time of a single reactor, incapability of continuously supplementing heat for solid particles and the like in a C-type ultrafine particle fluidized bed CVD coating technology are solved, repeated relay coating under the condition of the same raw material and multi-layer coating of different raw materials under the condition of one-time passing can be realized, the yield and the yield of a target product are favorably improved, and the production cost is reduced. The operation stability of a fluidized bed reaction system is improved, and equipment investment and dust pollution are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of gas-solid fluidized beds, and in particular to a multi-stage series fluidized bed reaction system and a use method thereof. Background Art

[0002] Fluidized bed reactors have attracted more and more attention in the field of chemical vapor deposition (CVD) due to their advantages such as high heat and mass transfer efficiency, uniform bed temperature, and large operational flexibility. Fluidized bed CVD technology can be used to uniformly coat one or more functional films or coatings on the surface of ultrafine solid particles, greatly improving their performance and application areas. For example, using fluidized bed CVD technology to coat the surface of ultrafine graphite with silicon and / or amorphous carbon can greatly improve the capacity, stability, and rate performance of lithium-ion batteries.

[0003] However, the particle size of ultrafine solid particles used for fluidized bed coating is generally less than 20 μm, and they belong to Class C particles according to the Geldart particle classification method. There are strong van der Waals forces and electrostatic forces between their particles. During the fluidization process, channeling, agglomeration, aggregation or node surges are easily generated, causing bed pressure instability and serious deterioration of the coating effect. This phenomenon is particularly prominent in the commonly used upward fluidized bed. In addition, the above-mentioned coating reactions are mostly strongly endothermic reactions, and heat needs to be continuously added to the system during the reaction process. In order to solve this problem, the existing technology generally adopts an external heating furnace in a fixed fluidized bed reactor or a rotary tunnel kiln reactor mode. The common disadvantages are low reaction efficiency, uneven coating layer or agglomerate coating phenomenon, and it is difficult to apply the coating process of a variety of raw materials, which has become a technical problem that needs to be solved in the field of ultrafine solid particle coating.

[0004] The existing Chinese invention patent CN114950283B discloses a fluidized reaction device for coating the surface of ultrafine particles and a method of using the same. The ultrafine particles are uniformly coated on the surface of the ultrafine particles by circulating multiple times between the descending fluidized reaction zone and the ascending fluidized reaction zone, which effectively solves the fluidization and wall adhesion reaction problems existing in the ultrafine particle fluidized CVD coating technology and improves the yield and quality of ultrafine powder coating materials. However, since there is only one descending bed reactor, the residence time of the ultrafine particles therein is limited. Each coating raw material requires multiple cycle reactions to achieve a sufficient coating layer thickness, and each production cycle can only complete the coating process of one raw material. There are still many problems caused by low product yield and difficulty in switching between different coating raw materials. Chinese invention patent CN105130727B discloses a three-stage series fluidized bed reactor for methanol to olefins reaction and a method for preparing olefins using the reactor. After the reaction product and the unreacted methanol raw material are separated from the catalyst, they enter the next reactor to continue the reaction. The catalyst flows continuously in the three-stage reactor. The first reactor adopts a fast bed, the second reactor adopts a turbulent bed, and the third reactor adopts a bubbling bed. The invention adopts a multi-stage series reactor to achieve graded utilization of the catalyst, maximizes the performance of the catalyst, and reduces the charcoal burning load of the regenerator. However, since the present invention is developed based on the characteristics of the methanol to olefins reaction, its reactor is in the form of an ascending fluidized bed, and each stage of the reactor adopts a parallel arrangement mode. Its catalyst meets the technical requirements of ordinary fluidized bed B-type particles, and the catalyst particles need to be continuously ascended and mixed in the reactor. Therefore, the residence time of the catalyst in the same reactor varies greatly, which is completely unsuitable for the fluidization and coating process of C-type ultrafine particles. Chinese invention patent CN102766480B discloses a two-stage series fluidized bed pyrolysis gasification device for solid organic fuel, comprising a primary fluidized bed reactor and a secondary fluidized bed reactor, a gas-solid separation device and a gas-liquid separation device arranged in series up and down. First, the organic solid fuel is burned or gasified in the primary fluidized bed reactor, and the discharged high-temperature flue gas or fuel gas is sent to the secondary fluidized bed reactor for gasification or pyrolysis. The organic solid raw material is used as the reaction raw material of the secondary fluidized bed, and the unburned solids of the secondary fluidized bed and the newly entered organic solid raw materials are used as the combustion raw materials of the primary fluidized bed. The advantage is that the heat released during the combustion or gasification of the organic solid fuel is fully utilized, which not only improves the quality of the pyrolysis gas, but also can produce high-quality and high-calorific value solid fuel, fuel gas and tar products; although the two-stage fluidized bed of the invention adopts the form of upper and lower series connection, its reactors are all upward fluidized beds and the supply process of the raw materials is completely different from the fluidized bed CVD coating, so it is also not suitable for the fluidized coating process of Class C ultrafine particles.

[0005] To this end, we designed a multi-stage series fluidized bed reaction system and its use method. Summary of the invention

[0006] In order to overcome the deficiencies in the background technology, the present invention discloses a multi-stage serial fluidized bed reaction system, which aims to solve the problems existing in the fluidized bed CVD coating technology of Class C ultrafine solid particles, such as short residence time of a single reactor, inability to continuously replenish heat for the solid particles, multiple circulations of solid particles required to achieve sufficient coating layer thickness, and only one raw material coating process can be completed in each production cycle. The purpose of simultaneously achieving coating of multiple raw materials and increasing the yield of target products is achieved in the multi-stage serial descending fluidized bed reaction system.

[0007] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0008] A multi-stage series fluidized bed reaction system, comprising a gas-solid separation zone, a multi-stage series reaction zone and a solid material receiving circulation zone, which are sequentially connected from top to bottom;

[0009] The segmented reaction zone of the multi-stage series reaction zone has a reactor and a hopper connected from top to bottom, the reactor cavity is provided with a distributor, the bottom is provided with a stepped material disperser without a bottom, the side wall of the distributor is connected to a coated raw material feed line, the bottom of the hopper is connected to a loose air feed line, and the bottom of the hopper is connected to the next segmented reaction zone or the solid material receiving circulation zone through a plug valve;

[0010] The cladding material feed line and the loose air feed line have preheating components as required;

[0011] The periphery of the dense phase zone of the reactor and the periphery of the storage container are both wrapped with reaction heaters; the gas phase outlet at the top of the reactor is connected to the gas-solid separation zone;

[0012] The solid material receiving circulation area includes a feed pipe whose upper end is connected to the multi-stage series reaction area, the lower end of the feed pipe is connected to a product tank, and the body of the feed pipe is connected to a solid product sampling assembly, a lifting pipe and a lifting air duct, wherein the upper end of the lifting pipe is connected to the gas-solid separation area, and the outlet of the lifting air duct corresponds to the inlet of the lifting pipe;

[0013] Specifically, the riser, the solid product sampling assembly and the product tank all have control valves;

[0014] The lift duct has a preheating component as required.

[0015] Preferably, the gas-solid separation zone has, from top to bottom, a gas collecting chamber, an upper separation chamber and a lower separation chamber, the inner top wall of the upper separation chamber is evenly distributed with multiple filters whose gas phase outlets are connected to the gas collecting chamber, the lower separation chamber is provided with multiple / groups of cyclone separators whose gas phase outlets are connected to the upper separation chamber, and the cyclone separators are connected one by one with the gas phase outlets and risers of each segmented reaction zone in the multi-stage series reaction zone; the top of the gas collecting chamber is connected with an exhaust gas outlet line, and the bottoms of the upper separation chamber and the lower separation chamber have discharge channels correspondingly connected to the feed inlets of the multi-stage series reaction zones.

[0016] Preferably, the bottoms of the upper separation chamber and the lower separation chamber are both inclined upward and downward, and the lower end of the bottom of the lower separation chamber is provided with a separation zone discharge pipe corresponding to the solid particle filling and preheating zone, and the lower end of the bottom of the upper separation chamber is provided with an upper separation chamber discharge pipe with a discharge port close to the separation zone discharge pipe;

[0017] Preferably, a solid particle filling and preheating zone is provided between the gas-solid separation zone and the multi-stage series reaction zone;

[0018] The solid particle filling and preheating zone includes an intermediate tank whose top feed port is connected to the discharge channel of the gas-solid separation zone, the top feed port of the intermediate tank is also connected to a solid particle filling line, an intermediate tank heater is wrapped around the outer periphery of the intermediate tank, and a feed control valve corresponding to the feed ports of the multi-stage series reaction zones is provided at the bottom of the intermediate tank.

[0019] Preferably, the multiple series reaction zones are arranged from top to bottom in a straight line, slanting downward or in a Z shape.

[0020] Preferably, the reaction heater adopts a heater with zone heating and temperature control functions.

[0021] Preferably, the distributor is located at the junction of the material disperser and the reactor.

[0022] The present invention also provides a method for using a multi-stage series fluidized bed reaction system, which is characterized by comprising the following process:

[0023] Process 1: solid particles enter the first segmented reaction zone of the multi-stage series reaction zone, and the reactor in the segmented reaction zone moves downward uniformly, the coating raw material enters the reactor from the distributor through the coating raw material feed line, the upward coating raw material contacts the downward solid particles in reverse to react with the coating, and a coating layer of a certain thickness is formed on the surface of the solid particles; the solid particles coated once enter the storage container along the material disperser, and then enter the loose fluidized state under the action of the fluidized loose wind entering through the loose wind feed line, and are reheated to the temperature required for the secondary coating reaction under the action of the reaction heater; finally, the solid particles enter the second segmented reaction zone of the multi-stage series reaction zone along the plug valve until they flow out of the multi-stage series reaction zone; the gas phase product carrying a small amount of solid particle fine powder in each segmented reaction zone of the multi-stage series reaction zone enters the gas-solid separation zone; wherein, the coating raw materials introduced into each segmented reaction zone of the multi-stage series reaction zone are the same or different;

[0024] Process 2: The coated particles flowing out of the multi-stage series reaction zone are divided into three routes: the first route is connected to the solid product sampling component, the second route is connected to the product tank, and the third route is connected to the lifting pipe; the coated particles are analyzed by the solid product sampling component. If the analysis is qualified, the lifting air duct is closed, and the qualified coated particles are sent to the product tank along the second route. If the analysis is unqualified, the lifting air duct is opened, and under the action of the lifting air transported through the lifting air duct, the coated particles enter the gas-solid separation zone along the lifting pipe;

[0025] Process 3: The solid particles separated from the gas-solid separation zone enter the first segmented reaction zone of the multi-stage series reaction zone again for cyclic coating operation.

[0026] Preferably, the fluidizing and loosening wind and the lifting wind are inert gases.

[0027] The present invention also provides another method for using a multi-stage series fluidized bed reaction system, which is characterized by comprising the following process:

[0028] Process 1: solid particles enter the first segmented reaction zone of the multi-stage series reaction zone, and the reactor in the segmented reaction zone moves downward uniformly, the coating raw material enters the reactor from the distributor through the coating raw material feed line, the upward coating raw material contacts the downward solid particles in reverse to react with the coating, and a coating layer of a certain thickness is formed on the surface of the solid particles; the solid particles coated once enter the storage container along the material disperser, and then enter the loose fluidized state under the action of the fluidized loose wind entering through the loose wind feed line, and are reheated to the temperature required for the secondary coating reaction under the action of the reaction heater; finally, the solid particles enter the second segmented reaction zone of the multi-stage series reaction zone along the plug valve until they flow out of the multi-stage series reaction zone; the gas phase product carrying a small amount of solid particle fine powder in each segmented reaction zone of the multi-stage series reaction zone enters the gas-solid separation zone; wherein, the coating raw materials introduced into each segmented reaction zone of the multi-stage series reaction zone are the same or different;

[0029] Process 2: The coated particles flowing out of the multi-stage series reaction zone are divided into three routes: the first route is connected to the solid product sampling component, the second route is connected to the product tank, and the third route is connected to the lifting pipe; the coated particles are analyzed by the solid product sampling component. If the analysis is qualified, the lifting air duct is closed, and the qualified coated particles are sent to the product tank along the second route. If the analysis is unqualified, the lifting air duct is opened, and under the action of the lifting air transported through the lifting air duct, the coated particles enter the gas-solid separation zone along the lifting pipe;

[0030] Process three, the gas-solid flow entering the cyclone separator is subjected to gas-solid separation in the corresponding cyclone separator, and the separated solid particles descend along the cyclone separator legs to the bottom of the inner cavity of the lower separation chamber; the gas containing a small amount of solid particle powder ascends from the cyclone separator outlet and enters the upper separation chamber, the gas therein passes through the filter into the gas collecting chamber, and leaves from the exhaust gas outlet line, the solid particle powder intercepted by the filter falls to the bottom of the inner cavity of the upper separation chamber, and the solid particles at the bottom of the lower separation chamber inner cavity and the bottom of the upper separation chamber inner cavity enter the first segmented reaction zone of the multi-stage series reaction zone again from the corresponding discharge channel for cyclic coating operation.

[0031] Preferably, the fluidizing loosening wind and lifting wind are inert gases.

[0032] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0033] 1. The combination of multiple series-connected descending fluidized bed reactors increases the residence time of solid particles in the reaction system, solving the problem of insufficient residence time in a single descending bed reactor;

[0034] 2. Heaters that can be heated and controlled independently are installed in the dense phase section and material storage section at the bottom of the reactor in each reaction area to supplement heat and raise the temperature of the solid particles that have undergone coating reaction multiple times, so as to flexibly increase sufficient heat for subsequent coating reactions;

[0035] 3. Different reaction areas can use the same coating raw material or different coating raw materials, which can realize multiple relay coating of solid particles under the same raw material atmosphere, or multiple raw materials and multiple layers of coating of solid particles in one pass, thereby improving the coating efficiency and product output of solid particles;

[0036] 4. The lower part of each reactor adopts a terraced material disperser with no bottom seal. The upward lifting effect of the fluidized loose wind in the storage section is used to form a stable dense phase bed at the lower part of the reactor, prolonging the residence time of solid particles in the reactor, which is conducive to increasing the thickness of the coating layer;

[0037] 5. Each reaction zone is connected to the lower separation chamber of the gas-solid separation zone through its own gas phase outlet line. Since the outlet pressure is exactly the same, the pressure of the fluidized bed reaction system can be kept stable to prevent the materials in each reaction zone from mixing with each other;

[0038] 6. The gas-solid separation zone and the multi-reaction zone are stacked in series up and down, which avoids multiple lifting of solid particles between different reactors, reduces equipment wear and the generation of fine powder, is conducive to improving the yield of coated products and extending the service life of the equipment;

[0039] 7. The gas-solid separation area is divided into multiple independent areas, and a combination of cyclone separation and filtration separation is used for solid-containing gas, which significantly improves the gas-solid separation efficiency and the recovery rate of ultrafine solid particles, reduces the dust content of exhaust gas, and is beneficial to protecting the production environment;

[0040] In summary, compared with the prior art, the present invention solves the problems existing in the fluidized bed CVD coating technology for Class C ultrafine particles, such as the short residence time of a single reactor and the inability to continuously replenish heat for solid particles. It can realize multiple relay coatings with the same raw material and multi-layer coatings of different raw materials in one pass, which is beneficial to improving the yield and output of the target product, enhancing the stability of the operation of the fluidized bed reaction system, and reducing equipment investment and dust pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the present invention.

[0042] In the figure: I. Gas-solid separation zone:

[0043] 1-1, tail gas outlet line; 1-2, gas collecting chamber; 1-3, filter; 1-4, upper separation chamber; 1-5, circulating material cyclone; 1-6, three reverse cyclone; 1-7, two reverse cyclone; 1-8, one reverse cyclone; 1-9, lower separation chamber; 1-10, upper baffle of separation chamber; 1-11, lower baffle of separation chamber; 1-12, discharge pipe of upper separation chamber; 1-13, discharge pipe of separation zone;

[0044] II. Solid particle filling preheating area:

[0045] 2-1, solid particle filling line; 2-2, intermediate tank; 2-3, intermediate tank heater; 2-4, feed control valve;

[0046] III. First reaction zone:

[0047] 3-1, first reactor; 3-2, a heater; 3-3, a distributor; 3-4, a material disperser; 3-5, a material storage device; 3-6, a feed pipe; 3-7, a plug valve; 3-8, a raw material preheating component; 3-9, a fluidized loosening air preheating component; 3-10, a gas phase outlet line;

[0048] IV. Second reaction zone:

[0049] 4-1, second reactor; 4-2, second reactor heater; 4-3, second reactor distributor; 4-4, second reactor material disperser; 4-5, second reactor storage; 4-6, second reactor discharge pipe; 4-7, second reactor plug valve; 4-8, second reactor raw material preheating assembly; 4-9, second reactor fluidization loosening air preheating assembly; 4-10, second reactor gas phase outlet line;

[0050] V. The third reaction zone:

[0051] 5-1, the third reactor; 5-2, the three-reactor heater; 5-3, the three-reactor distributor; 5-4, the three-reactor material disperser; 5-5, the three-reactor storage device; 5-6, the three-reactor discharge pipe; 5-7, the three-reactor plug valve; 5-8, the three-reactor raw material preheating component; 5-9, the three-reactor fluidized loosening air preheating component; 5-10, the three-reactor gas phase outlet line;

[0052] VI. Solid material receiving and circulation area:

[0053] 6-1, lifting air preheating assembly; 6-2, solid product sampling assembly; 6-3, discharge control valve; 6-4, product tank; 6-5, circulation control valve; 6-6, lifting pipe;

[0054] 7. One-rotation lead wire; 7-1. One anti-gas phase valve; 8. Two-rotation lead wire; 8-1. Two anti-gas phase valves; 9. Three-rotation lead wire; 9-1. Three anti-gas phase valves;

[0055] S, solid particles; F1, first-reverse coating raw material; F2, first-reverse fluidization loosening wind; F3, second-reverse coating raw material; F4, second-reverse fluidization loosening wind; F5, third-reverse coating raw material; F2, third-reverse fluidization loosening wind; F7, lifting wind; P1, tail gas; P2, intermediate sample; P3, solid product. DETAILED DESCRIPTION

[0056] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "back", "left", "right", etc. indicating directions or positional relationships, they only correspond to the drawings of the present application and are for the convenience of describing the present invention; it should be understood that if there are terms such as "end", "side", "end portion", "lateral", "lateral", "transverse", "longitudinal", etc. indicating directions or positional relationships, they only correspond to the length and width of the corresponding components, that is, the "end portion" indicates the head and tail areas in the length direction of the corresponding component, and the "side portion" indicates the head and tail areas in the width direction of the corresponding component; this is for the convenience of describing the present invention and is not to indicate or imply that the device or element referred to must have a specific direction.

[0057] Combined with Figure 1 , a multi-stage series fluidized bed reaction system, comprising a gas-solid separation zone I, a multi-stage series reaction zone and a solid material receiving circulation zone VI which are sequentially connected from top to bottom; as required, a solid particle filling preheating zone II can also be provided between the gas-solid separation zone I and the multi-stage series reaction zone.

[0058] For the convenience of explanation, the multi-stage series reaction zone is described as having three segmented reaction zones, which are respectively the first reaction zone III, the second reaction zone IV, and the third reaction zone V from top to bottom; wherein.

[0059] At this time, the reaction system includes a gas-solid separation zone I, a solid particle filling and preheating zone II, a first reaction zone III, a second reaction zone IV, a third reaction zone V and a solid material receiving and circulating zone VI; the gas-solid separation zone I is located at the top of the entire reaction system, and is connected to the solid particle filling and preheating zone II, the first reaction zone III, the second reaction zone IV, the third reaction zone V and the solid material receiving and circulating zone VI in sequence from top to bottom. The connecting channels therebetween are mainly used for the solid particles to flow from top to bottom, and the solid material receiving and circulating zone VI is connected to the gas-solid separation zone I via the riser 6-6 upward. , the solid particles that do not meet the coating requirements are lifted back to the gas-solid separation zone I, so that the circulation of most of the solid particles in the reaction system is established; the gas phase products of the first reaction zone III, the second reaction zone IV, and the third reaction zone V are connected to the gas-solid separation zone I through the corresponding gas phase outlet lines 3-10, 4-10, and 5-10, and the gas-solid separation is completed efficiently through the combination of cyclone separation + filtration, and a small amount of ultrafine solid particles and fine powders brought out by the gas phase products and the lifting wind are recovered. At the same time, the pressure of the reaction system can be kept stable to prevent the materials in each segmented reaction zone from mixing with each other;

[0060] The gas-solid separation zone I is the separation place of all gas phases and solid phases of the reaction system, including the tail gas outlet line 1-1, the gas collecting chamber 1-2, the filter 1-3, the upper separation chamber 1-4, the circulating material cyclone separator 1-5, the third anti-cyclone separator 1-6, the second anti-cyclone separator 1-7, the first anti-cyclone separator 1-8, the lower separation chamber 1-9, the upper partition plate 1-10 of the separation chamber, the lower partition plate 1-11 of the separation chamber, the upper separation chamber feed pipe 1-12 and the separation zone discharge pipe 1-13; the gas-solid separation The separation zone I is divided into three mutually isolated areas from top to bottom by the upper and lower partitions of the separation chamber: the gas collecting chamber 1-2, the upper separation chamber 1-4 and the lower separation chamber 1-9; as required, the gas collecting chamber 1-2 is in the shape of a flat cylinder, the top of which is connected to the tail gas outlet line 1-1, and the bottom surface, i.e., the upper partition 1-10 of the separation chamber, is sealed with a filter 1-3 with multiple gas phase outlets facing the gas collecting chamber 1-2. As required, the pore size of the filter 1-3 is 1 μm, and its function is to counteract the cyclone. The solid particle fine powder not removed by the separator is filtered and separated, which greatly reduces the content of solid particles in the exhaust gas and maximizes the yield of solid particles; the bottom surface of the upper separation chamber 1-4 located in the middle of the gas-solid separation zone I, that is, the lower partition 1-11 of the separation chamber is an inclined structure; it should be noted that: the angle between the bottom surface of the upper separation chamber 1-4 and the horizontal plane must be greater than the repose angle of the solid particles used, the first anti-cyclone separator 1-8, the second anti-cyclone separator 1-7, the third anti-cyclone separator 1- 6 and the gas phase outlet line of the circulating material cyclone separator 1-5 pass through the lower partition 1-11 of the separation chamber and are connected to the upper separation chamber 1-4; the lower separation chamber 1-9 located in the lower area of ​​the gas-solid separation zone I is equipped with an anti-cyclone separator 1-8, a second anti-cyclone separator 1-7, a third anti-cyclone separator 1-6 and a circulating material cyclone separator 1-5, and its lower bottom surface is an inclined structure. It should be noted that: the angle between the bottom surface of the lower separation chamber 1-9 and the horizontal plane must be greater than the repose angle of the solid particles used;

[0061] According to the needs, the first anti-cyclone separator 1-8, the second anti-cyclone separator 1-7, the third anti-cyclone separator 1-6 and the circulating material cyclone separator 1-5 can adopt a single-stage mode or a multi-stage mode in which multiple units are connected in series or in parallel.

[0062] The upper separation chamber discharge pipe 1-12 is installed at a position close to the wall of the separation chamber at the lowest point, and extends downward to a position close to the lower middle part of the lower separation chamber, so as to introduce the solid particle powder collected by the upper separation chamber 1-4 into the lower separation chamber 1-9; the separation zone discharge pipe position 1-13 is located at the lowest end of the lower separation chamber 1-9, and its outlet is connected to the top of the intermediate tank 2-2, so as to circulate the solid particles collected in the gas-solid separation zone I back to the intermediate tank 2-2.

[0063] Solid particle filling and preheating zone II is the place for filling fresh solid particles and preheating circulating solid particles in the reaction system, including solid particle filling line 2-1, intermediate tank 2-2, intermediate tank heater 2-3 and feed control valve 2-4; solid particle filling line 2-1 and separation zone discharge pipe 1-13 are both connected from the top of the intermediate tank, and the intermediate tank heater 2-2 is wrapped around the outside of the intermediate tank 2-2 to heat the solid particles entering the intermediate tank to the temperature required for a coating reaction; the feed control valve 2-4 is installed on the discharge pipeline at the bottom of the intermediate tank, which can accurately control the flow rate of solid particles entering the first reactor 3-1;

[0064] The first reaction zone III is a primary coating reaction site for solid particles in the reaction system, comprising a first reactor 3-1, a reverse heater 3-2, a reverse distributor 3-3, a reverse material disperser 3-4, a reverse accumulator 3-5, a reverse feed pipe 3-6, a reverse plug valve 3-7, a reverse raw material preheating assembly 3-8, a reverse fluidized loosening wind preheating assembly 3-9 and a reverse gas phase outlet line 3-10; wherein the first reactor 3-1 is located at the top of the first reaction zone III, and is connected downward in sequence to a reverse accumulator 3-5, a reverse plug valve 3-7 and a reverse feed pipe 3-6; the first reactor 3-1 is cylindrical at the top and a terraced, bottomless reverse material disperser 3-4, such a structure can utilize the upward lifting effect of the fluidized loosening wind of the reverse storage container 3-5 to form a stable dense phase bed at the bottom of the reverse heater 3-2, prolong the residence time of the solid particles in the reverse heater 3-2, and help increase the thickness of the coating layer; a reverse distributor 3-3 is located at the junction of the first reactor cylinder and the reverse material disperser 3-4, and the reverse distributor 3-3 passes through the reverse heater from the side wall. The cylinder of the reactor 3-2 is connected with a reverse coating raw material feeding line and a reverse raw material preheating assembly 3-8; that is, a reverse coating raw material enters a reverse distributor 3-3 through a reverse coating raw material feeding line; a reverse accumulator 3-5 is of equal diameter to the cylinder of the first reactor 3-1 and is sealed and connected to the lower part of the first reactor 3-1; a reverse loosening air feeding line passes through a reverse loosening air preheating assembly 3-9 and then passes through the wall of the reverse accumulator 3-5 from the side to enter the bottom of the reverse accumulator 3-5; that is, a reverse fluidized loosening air F2 enters the reverse accumulator 3-5 through a reverse loosening air feeding line; A reverse heater 3-2 is wrapped around the lower dense phase section of the first reactor and the outside of a reverse storage container 3-5; as needed, the reverse heater 3-2 can adopt a zone heating and temperature control method corresponding to the above two areas to achieve the function of flexibly adjusting the temperature of different areas, and conveniently achieve the reheating of the solid particles after the coating reaction; an anti-gas phase outlet line 3-10 is connected to the top of the reverse heater 3-2, and is connected to an anti-cyclone separator 1-8 through a cyclone lead 7; the first reaction zone III is connected to the second reaction zone IV through a reverse feed pipe 3-6;

[0065] It should be noted that: the anti-distributor 3-3 is an existing device, and its specific structure and operating principle will not be repeated here.

[0066] It should be noted that: the first reaction storage container 3-5 is open at the upper end, and the upper edge of the first reaction material disperser 3-4, the upper edge of the first reaction storage container 3-5 and the lower edge of the first reactor 3-1 are connected together.

[0067] The second reaction zone IV and the third reaction zone V are respectively the secondary and tertiary coating reaction sites of the solid particles in the reaction system. According to needs, their structural compositions and connection methods are exactly the same as those of the first reaction zone I. The solid particles flowing out of the previous reaction zone undergo the same process as that of the first reaction zone, which will not be described in detail here. It is only necessary to explain that: the second reverse coating raw material F3 of the second reaction zone IV enters the second reaction zone IV through the second reverse coating raw material feed line, and the second reverse fluidized loosening wind F4 of the second reaction zone IV enters the second reaction zone IV through the second reverse loosening wind feed line; the third reverse coating raw material F5 of the third reaction zone V enters the third reaction zone V through the third reverse coating raw material feed line, and the third reverse fluidized loosening wind F6 of the third reaction zone V enters the third reaction zone V through the third reverse loosening wind feed line.

[0068] According to the needs, the first reaction zone III, the second reaction zone IV, and the third reaction zone V can be reduced to 2, or increased to more than 3; their layout can be attached Figure 1 The "Z" shape shown can also be arranged in a way that it tilts leftward or rightward from top to bottom; this multiple reaction zones are stacked in series, which increases the residence time of solid particles in the reaction system, solves the problem of insufficient residence time of a single down-flowing bed reactor, and also avoids multiple lifting of solid particles between different reactors, reduces equipment wear and the generation of fine powder, and is conducive to improving the yield of coated products and extending the service life of the equipment;

[0069] The solid material receiving circulation area VI is a place for sampling and analysis of solid particles after coating reaction, product recovery and recycling of solid particles that do not meet the coating thickness requirements, including a lifting air preheating component 6-1, a solid product sampling component 6-2, a discharge control valve 6-3, a product tank 6-4, a circulation control valve 6-5 and a lifting pipe 6-6; the three-reaction discharge pipe 5-6 of the third reaction zone V is inclined downward and connected to the lifting pipe 6-6, the solid product sampling component 6-2, the discharge control valve 6-3 and the product tank 6-4 in sequence; the lifting air preheating component 6-1 is connected to the inlet end (the lowest end) of the lifting pipe 6-6, and the outlet end of the lifting pipe 6-6 is connected to the circulating material cyclone separator 1-5 in the gas-solid separation area.

[0070] It should be noted that the above-mentioned heater, preheating component and solid product sampling component all adopt existing equipment, and their structural structure and operating principle will not be repeated here.

[0071] A method for using a multi-stage series descending fluidized bed reaction system, comprising the following use process:

[0072] Process 1: Filling and preheating of solid particles

[0073] Solid particles S are added into the intermediate tank 2-2 along the solid particle filling line 2-1, and the solid particles are preheated to the temperature required for the primary coating reaction by the intermediate tank heater 2-3, and then uniformly enter the top of the first reactor 3-1 at a certain outflow rate through the feed control valve 2-4;

[0074] Process 2: primary coating reaction

[0075] The solid particles entering the top of the first reactor 3-1 move downward uniformly. After being heated to a predetermined temperature by a reverse raw material preheating assembly 3-8, the first reverse coating raw material F1 enters from a reverse distributor 3-3 located at the lower part of the first reactor 3-1. The upward first reverse coating raw material F1 contacts the downward hot solid particles in reverse order to cause a coating reaction, and a coating layer of a certain thickness is formed on the surface of the solid particles. The solid particles that have been coated once enter an reverse storage container 3-5 along an reverse material disperser 3-4, and are then in a loose fluidized state under the action of a reverse fluidizing loosening wind F2 preheated by a reverse fluidizing loosening wind preheating assembly 3-9. At the same time, they are reheated to the temperature required for the secondary coating reaction under the action of a reverse heater 3-2. Then, they are moved along a reverse plug valve 3-7 and a reverse stop valve 3-8. The reverse feed pipe 3-6 feeds the second reactor 4-1 from the top of the second reactor; the presence of a reverse fluidized loosening wind F2 promotes the speed at which the solid particles are heated again. At the same time, the reverse fluidized loosening wind F2 also limits the flow of the primary coated particles from the first reactor 3-1 to the reverse storage tank 3-5 during the upward process from the reverse material disperser 3-4, which helps to form a dense phase section at the bottom of the first reactor 3-1 and prolong the residence time and reaction time of the primary coated particles in the first reactor 3-1; a reverse gas phase product carrying a small amount of solid particle fine powder enters an anti-cyclone separator 1-8 in the gas-solid separation zone along an anti-gas phase outlet line 3-10 and a cyclone lead 7; according to needs, the reverse fluidized loosening wind F2 is an inert gas, preferably nitrogen;

[0076] Process 3, secondary coating reaction

[0077] The primary coated solid particles entering the second reactor 4-1 undergo a reaction and reheating process similar to process 2 under the action of the secondary coating raw material F3, the secondary fluidized loosening wind F4 and the secondary heater 4-2. The secondary gas phase product carrying a small amount of solid particles enters the secondary cyclone separator 1-7 in the gas-solid separation zone along the secondary gas phase outlet line 4-10 and the secondary cyclone lead 8. The secondary coated particles preheated again in the secondary storage tank 4-5 are fed into the third reactor 5-1 from the top of the third reactor through the secondary plug valve 4-7 and the secondary discharge pipe 4-6 at a certain flow rate; the secondary coating raw material F3 can be the same as the primary coating raw material F1, or different from the primary coating raw material F1; according to needs, the secondary fluidized loosening wind F4 is an inert gas, preferably nitrogen;

[0078] Process 4, three-coating reaction

[0079] The secondary coated solid particles entering the third reactor 5-1 undergo a reaction and reheating process similar to process 2 under the action of the three-reverse coating raw material F5, the three-reverse fluidized loosening wind F6 and the three-reverse heater 5-2. The three-reverse gas phase product carrying a small amount of solid particle fine powder enters the three-reverse cyclone separator 1-6 in the gas-solid separation zone along the three-reverse gas phase outlet line 5-10 and the three-cyclone lead 9. The preheated three-coated particles in the three-reverse storage container 5-5 enter the solid material receiving circulation zone VI through the three-reverse plug valve 5-7 and the three-reverse discharge pipe 5-6 at a certain flow rate; the three-reverse coating raw material F5 can be the same as the first-reverse coating raw material F1 and the second-reverse coating raw material F3, or different from the first-reverse coating raw material F1 and the second-reverse coating raw material F3; according to needs, the second-reverse fluidized loosening wind F4 is an inert gas, preferably nitrogen;

[0080] Process 5: Receiving and recycling of solid materials

[0081] The tertiary coated particles flowing out of the three-reaction discharge pipe 5-6 are divided into three routes, wherein the first route is connected to the solid product sampling component 6-2, the second route is connected to the discharge control valve 6-3 and the product tank 6-4, and the third route is connected to the lifting pipe 6-6; the tertiary coated particles are sampled as the intermediate product P2 through the solid product sampling component 6-2. If P2 is qualified in the analysis, the circulation control valve 6-5 is closed, the discharge control valve 6-3 is opened, and the qualified solid particles are sent to the product tank 6-4 along the second route as the solid product P3; if P2 is unqualified, the circulation control valve 6-5 is opened, the discharge control valve 6-3 is closed, and under the action of the lifting air F7 preheated by the lifting air preheating component 6-1, the lifting air F7 is transported to the circulating material cyclone separator 1-5 of the gas-solid separation zone I along the lowest end of the lifting pipe 6-6; as needed, the lifting F7 is an inert gas, preferably nitrogen;

[0082] Process 6: Gas-solid separation

[0083] The gas-solid flow entering the first anti-cyclone separator 1-8, the second anti-cyclone separator 1-7, the third anti-cyclone separator 1-6 and the circulating material cyclone separator 1-5 is subjected to gas-solid separation in the corresponding cyclone separators, and the separated solid particles flow down along the cyclone separator legs to the inclined bottom plate of the lower separation chamber 1-9, and slide along the bottom plate to the lowest point of the lower separation chamber; the gas containing a small amount of solid particle fine powder that flows upward from the cyclone separator outlet enters the upper separation chamber 1-4, and the gas therein passes through the filter 1-3 and enters the gas collecting chamber 1-2 as The tail gas P1 leaves the multi-stage series fluidized bed reaction system along the tail gas outlet line 1-1, and the solid particle fine powder intercepted by the filter 1-3 falls onto the inclined lower partition 1-11 of the separation chamber, and slides along the lower partition 1-11 of the separation chamber to the upper separation chamber discharge pipe 1-12, and then flows downward from the upper separation chamber discharge pipe 1-12 into the lower separation chamber 1-9, and together with the solid particle fine powder flowing down from the cyclone separator leg of the lower separation chamber, enters the intermediate tank 2-2 from the top along the separation area discharge pipe 1-13, thereby completing the circulation coating process of the solid particle material.

[0084] It should be noted that: if it is necessary to control the thickness of the coating layer formed on the surface of the solid particles by the same coating raw material, it can be achieved by adjusting the flow rate of the feed control valve of the solid particle filling preheating zone and using the same coating raw material in different reaction zones, as well as by using a combination of them. If the above means have not yet achieved the required coating layer thickness, the method of circulating the solid particles again can be continued. If it is necessary to achieve the coating of two or more coating raw materials, and there are requirements for the coating layer thickness of each raw material, after one raw material reaches the coating requirement, it can be switched to another raw material for cyclic coating. The smaller the solid particle circulation amount or the more cycles, the thicker the coating layer, and vice versa.

[0085] Example 1: The reaction system comprises two reaction zones connected in series, each of which uses the same coating raw material and different temperature conditions, and the solid particles pass through once without circulation;

[0086] Specifically, the solid S to be coated is graphite particles with a D50 particle size of 8 μm; the first-coating raw material F1 and the second-coating raw material F3 are both a mixture of acetylene (C2H2) and hydrogen (H2), wherein the molar ratio of acetylene is 0.30; the first-coating fluidized loosening wind F2 and the second-coating fluidized loosening wind F4 are high-purity nitrogen with a purity of 99.999%; the gas stripping wind is ordinary nitrogen with a purity of 99.9%;

[0087] Open the first anti-gas phase valve 7-1 and the second reaction gas phase valve 8-1;

[0088] 24 kg of graphite particles are added to the intermediate tank 2-2 along the solid particle filling line 2-1, the intermediate tank heater 2-4 is turned on, the graphite particles in the intermediate tank 2-2 are preheated to 920±5°C, and the feed control valve 2-4 is opened to allow the preheated graphite particles to enter the first reactor 3-1 of the first reaction zone I at a rate of 6 kg / h; a reverse coating raw material F1 preheated to 750±3°C by a reverse raw material preheating component 3-9 enters the bottom of the first reactor from a reverse distributor 3-3 at a flow rate of 1000NL / h, and C2H2 gas ascends along the reactor, contacts with the descending hot graphite particles and reacts chemically, C2H2 decomposes into H2 and amorphous carbon at high temperature, and the amorphous carbon wraps the surface of the graphite particles to form a carbon coating layer; the bed center temperature of the first reactor 3-1 is controlled at 760±5°C, and the operating pressure is controlled at 65±2KPaG; since the reaction is an endothermic reaction, the temperature of the graphite particles decreases after the reaction. The temperature of the graphite particles coated once flows from a reverse material disperser 3-4 into a reverse storage tank 3-5, and a reverse fluidized loose wind preheating component 3-9 is preheated to high-purity nitrogen of about 800°C, and introduced into the reverse storage tank 3-5 at a flow rate of 280NL / h to make the graphite particles therein in a loose fluidized state; a reverse heater 3-2 is turned on to make the dense phase section at the lower part of the first reactor 3-1 and the once coated graphite particles in the reverse storage tank 3-5 The temperature is raised again to 950±5℃; a reverse fluidized loose wind F2 passes through a reverse storage tank 3-5, and then goes up from a reverse material disperser 3-4 into the first reactor 3-1, so that a dense phase section is formed at the lower part of the reactor; the fluidized loose wind entering the dense phase section of the first reactor is mixed with the H2 generated in the reaction process, and then leaves the first reactor from a reverse gas phase outlet line 3-10, and then enters a reverse cyclone 1-8 located in the gas-solid separation zone I along a cyclone lead 7 for gas-solid separation;

[0089] The opening of the first reverse plug valve 3-7 is controlled to allow the graphite particles that have been coated once to flow down the first reverse feed pipe 3-6 into the second reactor 4-1 at a rate of 6 kg / h; the first reverse coated raw material F3 preheated to 780±3°C by the second reverse raw material preheating assembly 3-9 enters the bottom of the second reactor from the second reverse distributor 4-3 at a flow rate of 1200NL / h, and the C2H2 gas flows upward along the reactor, contacts with the descending hot graphite particles and reacts chemically, and C2H2 decomposes into H2 and amorphous carbon at high temperature, and the amorphous carbon wraps the surface of the graphite particles to form a carbon coating layer; the bed center temperature of the second reactor 4-1 is controlled at 790±5°C, and the operating pressure is controlled at 65±2KPaG; since the reaction is an endothermic reaction, the temperature of the graphite particles decreases after the reaction. The temperature of the second reverse material is about 780°C; the graphite particles after secondary coating flow from the second reverse material disperser 4-4 into the second reverse storage tank 4-5, and the second reverse fluidized loose wind preheating component 4-9 is preheated to high-purity nitrogen of about 800°C, and introduced into the second reverse storage tank 4-5 at a flow rate of 260NL / h to make the graphite particles therein in a loose fluidized state; after the second reverse fluidized loose wind F2 passes through the second reverse storage tank 4-5, it goes up from the second reverse material disperser 4-4 into the second reactor 3-1, so that a dense phase section is formed at the lower part of the reactor; the fluidized loose wind entering the dense phase section of the second reactor is mixed with the H2 generated in the reaction process, and then leaves the second reactor from the second reverse gas phase outlet line 4-10, and then enters the second reverse cyclone 1-7 located in the gas-solid separation zone I along the second cyclone lead 8 for gas-solid separation;

[0090] The operating temperature of the gas-solid separation zone I is controlled to be 790±5°C, and the operating pressure is the same as the pressure of each reaction zone; the ultrafine graphite particles separated from the first anti-rotation fraction 1-8, the second anti-rotation fraction 1-7 and the filter 1-3 flow down the discharge pipe of the separation zone into the intermediate tank 2-2 to continue to participate in the coating reaction;

[0091] Since the feed amount of solid particles is reduced and the feed amount of coating raw materials is increased, after two amorphous carbon coatings, sampling and analysis are carried out through the solid product sampling component 6-2. The analysis results show that the thickness of amorphous carbon on the surface of the graphite particles after two coatings meets the technical requirements and does not need to be circulated and coated again; close the second reverse heater 4-2 and the circulation control valve 6-6, open the discharge control valve 6-3, and transfer all qualified products into the product tank 6-4.

[0092] In this embodiment, two reactors with the same coating raw material are connected in series and passed through the process once, and a total of 24.64 kg of graphite particle coating products that meet the requirements are obtained.

[0093] Example 2: The reaction system comprises two reaction zones connected in series, each reaction zone uses the same coating raw material and the same reaction conditions, and the solid particles are cyclically coated;

[0094] Specifically, the solid S to be coated is graphite particles with a D50 particle size of 8 μm; the first-coating raw material F1 and the second-coating raw material F3 are both a mixture of acetylene (C2H2) and hydrogen (H2), wherein the molar ratio of acetylene is 0.15; the first-coating fluidized loosening wind F2 and the second-coating fluidized loosening wind F4 are high-purity nitrogen with a purity of 99.999%; the gas stripping wind is ordinary nitrogen with a purity of 99.9%;

[0095] Open the first anti-gas phase valve 7-1 and the second anti-gas phase valve 8-1;

[0096] 20 kg of graphite particles are added to the intermediate tank 2-2 along the solid particle filling line 2-1, the intermediate tank heater 2-4 is turned on, the graphite particles in the intermediate tank 2-2 are preheated to 950±5°C, and the feed control valve 2-4 is opened to allow the preheated graphite particles to enter the first reactor 3-1 of the first reaction zone I at a rate of 10 kg / h; a reverse coating raw material F1 preheated to 800±3°C by a reverse raw material preheating component 3-9 enters the bottom of the first reactor from a reverse distributor 3-3 at a flow rate of 1500NL / h, and C2H2 gas ascends along the reactor, contacts with the descending hot graphite particles and reacts chemically, C2H2 decomposes into H2 and amorphous carbon at high temperature, and the amorphous carbon wraps the surface of the graphite particles to form a carbon coating layer; the bed center temperature of the first reactor 3-1 is controlled at 780±5°C, and the operating pressure is controlled at 75±2KPaG; since the reaction is an endothermic reaction, the temperature of the graphite particles decreases after the reaction. The graphite particles after the primary coating flow from the first material disperser 3-4 into the first storage tank 3-5, and the high-purity nitrogen gas preheated to about 800°C by the first fluidized loose wind preheating component 3-9 is introduced into the first storage tank 3-5 at a flow rate of 320NL / h to make the graphite particles therein in a loose fluidized state; the first heater 3-2 is turned on to make the first coated graphite particles in the lower dense phase section of the first reactor 3-1 and the first storage tank 3-5 The temperature is raised again to 950±5℃; a reverse fluidized loose wind F2 passes through a reverse storage tank 3-5, and then goes up from a reverse material disperser 3-4 into the first reactor 3-1, so that a dense phase section is formed at the lower part of the reactor; the fluidized loose wind entering the dense phase section of the first reactor is mixed with the H2 generated in the reaction process, and then leaves the first reactor from a reverse gas phase outlet line 3-10, and then enters a reverse cyclone 1-8 located in the gas-solid separation zone I along a cyclone lead 7 for gas-solid separation;

[0097] The second reaction zone uses the same raw materials and feed amount, operating conditions and operating procedures as the first reaction zone;

[0098] Sampling and analysis are performed through the solid product sampling component 6-2. The analysis results show that the thickness of amorphous carbon on the surface of the graphite particles after two coatings does not meet the technical requirements and needs to be recycled and coated again; the second reverse heater 4-2 and the circulation control valve 6-6 are opened, and the discharge control valve 6-3 is closed; the lifting air F7 is preheated to 790±5℃ by the lifting air preheating component 6-1, and the unqualified secondary coated graphite particles are sent to the circulating material cyclone 1-5 in the gas-solid separation area along the lifting pipe 6-6 by the lifting air F7 for gas-solid separation;

[0099] The operating temperature of the gas-solid separation zone I is controlled to be 790±5°C, and the operating pressure is the same as the pressure of each reaction zone; the ultrafine graphite particles separated from the first anti-cyclonic fraction 1-8, the second anti-cyclonic fraction 1-7, the circulating material cyclonic fraction 1-5 and the filter 1-3 flow down the discharge pipe of the separation zone into the intermediate tank 2-2 to continue to participate in the coating reaction;

[0100] This embodiment adopts two reactors connected in series for two cycles of the same coating raw material, and obtains a total of 24.43 kg of graphite particle coating products that meet the requirements.

[0101] Example 3: The reaction system comprises three reaction zones connected in series, each of which uses the same coating raw materials and reaction conditions;

[0102] Specifically, the solid S to be coated is graphite particles with a D50 particle size of 8 μm; the first-coating raw material F1, the second-coating raw material F3 and the third-coating raw material F5 are all a mixture of acetylene (C2H2) and hydrogen (H2), wherein the molar ratio of acetylene is 0.15; the first-coating fluidized loosening wind F2, the second-coating fluidized loosening wind F4 and the third-coating fluidized loosening wind F6 are high-purity nitrogen with a purity of 99.999%; the gas stripping wind is ordinary nitrogen with a purity of 99.9%;

[0103] Open the first anti-gas phase valve 7-1, the second anti-gas phase valve 8-1 and the third anti-gas phase valve 9-1;

[0104] 50 kg of graphite particles are added to the intermediate tank 2-2 along the solid particle filling line 2-1, the intermediate tank heater 2-4 is turned on, the graphite particles in the intermediate tank 2-2 are preheated to 950±5°C, and the feed control valve 2-4 is opened to allow the preheated graphite particles to enter the first reactor 3-1 of the first reaction zone I at a rate of 10 kg / h; a reverse coating raw material F1 preheated to 750±3°C by a reverse raw material preheating component 3-9 enters the bottom of the first reactor from a reverse distributor 3-3 at a flow rate of 2000NL / h, and C2H2 gas ascends along the reactor, contacts with the descending hot graphite particles and reacts chemically, C2H2 decomposes into H2 and amorphous carbon at high temperature, and the amorphous carbon wraps the surface of the graphite particles to form a carbon coating layer; the bed center temperature of the first reactor 3-1 is controlled at 780±5°C, and the operating pressure is controlled at 70±2KPaG; since the reaction is an endothermic reaction, the temperature of the graphite particles decreases after the reaction. The graphite particles after the primary coating flow from the first material disperser 3-4 into the first storage tank 3-5, and the high-purity nitrogen gas preheated to about 800°C by the first fluidized loose wind preheating component 3-9 is introduced into the first storage tank 3-5 at a flow rate of 300NL / h to make the graphite particles therein in a loose fluidized state; the first heater 3-2 is turned on to make the first coated graphite particles in the lower dense phase section of the first reactor 3-1 and the first storage tank 3-5 The temperature is raised again to 950±5℃; a reverse fluidized loose wind F2 passes through a reverse storage tank 3-5, and then goes up from a reverse material disperser 3-4 into the first reactor 3-1, so that a dense phase section is formed at the lower part of the reactor; the fluidized loose wind entering the dense phase section of the first reactor is mixed with the H2 generated in the reaction process, and then leaves the first reactor from a reverse gas phase outlet line 3-10, and then enters a reverse cyclone 1-8 located in the gas-solid separation zone I along a cyclone lead 7 for gas-solid separation;

[0105] Open a reverse plug valve 3-7, and the graphite particles that have been coated once flow down a reverse feed pipe 3-6 into the second reactor 4-1;

[0106] The second reaction zone IV and the third reaction zone V adopt the same reaction conditions as the first reaction zone III;

[0107] The operating temperature of the gas-solid separation zone I is controlled to be 790±5°C, and the operating pressure is the same as the pressure of each reaction zone; the ultrafine graphite particles separated from the first anti-rotation fraction 1-8, the second anti-rotation fraction 1-7, the third anti-rotation fraction 1-6 and the filter 1-3 flow down the discharge pipe of the separation zone into the intermediate tank 2-2 to continue to participate in the coating reaction;

[0108] The graphite particles after three coating reactions go along the three-reverse discharge pipe 5-6 into the solid material receiving circulation area VI, and are sampled and analyzed through the solid product sampling component 6-2. The analysis results show that the thickness of amorphous carbon on the surface of the graphite particles after three coatings meets the technical requirements and does not need to be recycled and coated again. Close the circulation control valve 6-6, open the discharge control valve 6-3, and transfer all qualified products into the product tank 6-4.

[0109] In this embodiment, three reactors of the same coating raw material are connected in series and passed through the process once, and a total of 54.10 kg of graphite particle coating products that meet the requirements are obtained.

[0110] Example 4: The multi-stage serial descending fluidized bed reaction system comprises four reaction zones connected in series, the first and second reaction zones are used for coating silicon, using the same coating raw materials (methylsilane, SiH4 + hydrogen, H2) and reaction conditions, and the molar ratio of SiH4 to H2 is 0.20; the third and fourth reaction zones are used for coating amorphous carbon, using the same coating raw materials (acetylene, C2H2 + hydrogen, H2) and reaction conditions, and the molar ratio of C2H2 to H2 is 0.20;

[0111] The solid S to be coated is graphite particles with a D50 particle size of 8 μm; the first reverse fluidization loosening air, the second reverse fluidization loosening air, the third reverse fluidization loosening air, and the fourth reverse fluidization loosening air are high-purity nitrogen with a purity of 99.999%; the gas stripping air is ordinary nitrogen with a purity of 99.9%;

[0112] Open the gas phase valve on the cyclone lead from each reactor to the gas-solid separation zone;

[0113] 30kg of graphite particles are added into the intermediate tank 2-2 along the solid particle filling line 2-1, and the intermediate tank heater 2-4 is turned on to preheat the graphite particles therein to 720℃±5℃, and the operating pressure is controlled at 80±3KPaG; the feed control valve 2-4 is opened to allow the preheated graphite particles to enter the first reactor 3-1 in the first reaction zone at a rate of 10kg / h; a reverse coating raw material SiH4 preheated to 380±2℃ by a reverse raw material preheating component 3-9 enters the bottom of the first reactor from a reverse distributor 3-3 at a flow rate of 1800NL / h, and the SiH4 gas ascends along the reactor, contacts with the descending hot graphite particles and reacts chemically, and SiH4 is decomposed into H2 and Si at high temperature, Si coats the surface of graphite particles; since the reaction is an exothermic reaction, the center temperature of the bed of the first reactor 3-1 is controlled at 740±5°C and the operating pressure is controlled at 80±3KPaG by lowering the feed temperature and the preheating temperature of the graphite particles; the graphite particles coated once flow from an anti-material disperser 3-4 into an anti-stocker 3-5, and high-purity nitrogen preheated to about 400°C by an anti-fluidized loose wind preheating component 3-9 is introduced into the anti-stocker 3-5 at a flow rate of 300NL / h to make the graphite particles therein in a loose fluidized state; in order to reduce the temperature of the once coated graphite particles, a reverse heater 3-2 is turned off, and the once coated particles are cooled down to 720°C±5°C again by high-purity nitrogen;

[0114] The coating raw materials, operating conditions and operating process used in the second reactor of the second reaction zone are exactly the same as those of the first reactor mentioned above; before the third coating reaction, the particles that have undergone the secondary coating reaction need to be heated to a temperature that meets the temperature required for the third coating reaction, and the second reverse fluidized loosening air with a flow rate of 300NL / h is preheated to 800±5°C, and the second reverse heater 3-2 is turned on to preheat the graphite particles that have undergone the secondary coating reaction to 920±5°C; the opening of the second reverse plug valve 4-7 is controlled to allow the secondary coated particles to enter the third reactor 5-1 along the second reverse feed pipe 3-6 at a flow rate of 10kg / h;

[0115] The three-reaction coating raw material C2H2 preheated to 750±3℃ by the three-reaction raw material preheating component 5-8 enters the bottom of the third reactor from the three-reaction distributor 5-3 at a flow rate of 2000NL / h. The C2H2 gas goes up along the reactor and contacts the graphite particles that have undergone two silicon coating reactions. C2H2 is decomposed into H2 and amorphous carbon at high temperature, and the carbon coating reaction continues to occur around the silicon coating layer to form an amorphous carbon coating layer. The center temperature of the bed of the third reactor 5-1 is controlled at 800±5℃, and the operating pressure is controlled at 70±2KPaG. Since the reaction is an endothermic reaction, the temperature of the graphite particles after the reaction is reduced to about 790℃. The graphite particles that have undergone one carbon coating flow from the three-reaction material disperser 5-4 into the three-reaction storage tank 5-5, and the three-reaction fluidized loose air preheating device 5-6 is used to preheat the three-reaction raw material. The heat assembly 5-9 is preheated to high-purity nitrogen of about 800°C, and introduced into the three-reaction storage tank 5-5 at a flow rate of 350NL / h to make the graphite particles therein in a loose fluidized state; the three-reaction heater 5-2 is turned on to reheat the primary carbon-coated graphite particles in the lower dense phase section of the third reactor 5-1 and the three-reaction storage tank 5-5 to 920±5°C; the three-reaction fluidized loose wind F6 passes through the three-reaction storage tank 5-5, and then goes up from the three-reaction material disperser 5-4 into the third reactor 5-1, so as to form a dense phase section at the lower part of the reactor; the fluidized loose wind entering the dense phase section of the third reactor is mixed with the H2 generated in the reaction process, and then leaves the third reactor from the three-reaction gas phase outlet line 5-10, and then enters the three-reaction cyclone 1-6 located in the gas-solid separation zone I along the three-rotation lead 9 for gas-solid separation;

[0116] The fourth reaction zone uses the same types and feed amounts of coating raw materials as the third reaction zone, and the operating conditions and operating steps are also completely the same as those of the third reaction zone;

[0117] The operating temperature of the gas-solid separation zone I is controlled to be 790±5°C, and the operating pressure is the same as the pressure of each reaction zone; the ultrafine graphite particles separated from the first anti-rotation fraction, the second anti-rotation fraction, the third anti-rotation fraction, the fourth anti-rotation fraction and the filter flow down along the discharge pipe of the separation zone into the intermediate tank 2-2 to continue to participate in the coating reaction;

[0118] After the first and second reaction zones were connected in series to coat silicon, and the third and fourth reaction zones were connected in series to coat amorphous carbon, the product met the technical requirements and there was no need for cyclic coating of graphite particles. In this embodiment, a total of 32.24 kg of graphite particle coated products that met the requirements were obtained.

[0119] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and it is intended that all changes that fall within the meaning and scope of equivalent elements are included in the present invention.

Claims

1. A multi-stage series fluidized bed reaction system, characterized in that: It includes a gas-solid separation zone, a multi-stage series reaction zone and a solid material receiving circulation zone which are sequentially connected from top to bottom; The segmented reaction zone of the multi-stage series reaction zone has a reactor and a hopper connected from top to bottom, the reactor cavity is provided with a distributor, the bottom is provided with a stepped material disperser without a bottom, the side wall of the distributor is connected to a coated raw material feed line, the bottom of the hopper is connected to a loose air feed line, and the bottom of the hopper is connected to the next segmented reaction zone or the solid material receiving circulation zone through a plug valve; The periphery of the dense phase zone of the reactor and the periphery of the storage container are both wrapped with reaction heaters; the gas phase outlet at the top of the reactor is connected to the gas-solid separation zone; The solid material receiving circulation area includes a feed pipe whose upper end is connected to the multi-stage series reaction area, the lower end of the feed pipe is connected to the product tank, and the body of the feed pipe is connected to the solid product sampling component, the lifting pipe and the lifting air duct, wherein the upper end of the lifting pipe is connected to the gas-solid separation area, and the lifting air duct outlet corresponds to the lifting pipe inlet.

2. The multi-stage series fluidized bed reaction system according to claim 1, characterized in that: The gas-solid separation zone comprises an air collecting chamber, an upper separation chamber and a lower separation chamber from top to bottom, the inner top wall of the upper separation chamber is evenly distributed with filters whose gas phase outlets are connected to the air collecting chamber, the lower separation chamber is provided with multiple / groups of cyclone separators whose gas phase outlets are connected to the upper separation chamber, and the cyclone separators are connected one by one with the gas phase outlets and risers of each segmented reaction zone in the multi-stage series reaction zone; the top of the air collecting chamber is connected with an exhaust gas outlet line, and the bottoms of the upper separation chamber and the lower separation chamber are provided with discharge channels correspondingly connected to the feed inlets of the multi-stage series reaction zones.

3. The multi-stage serial fluidized bed reaction system according to claim 2, characterized in that: The bottoms of the upper separation chamber and the lower separation chamber are both inclined up and down, and the lower end of the bottom of the lower separation chamber is provided with a separation zone discharge pipe corresponding to the solid particle filling and preheating zone, and the lower end of the bottom of the upper separation chamber is provided with an upper separation chamber discharge pipe with a discharge port close to the separation zone discharge pipe.

4. The multi-stage series fluidized bed reaction system according to claim 1, characterized in that: A solid particle filling and preheating zone is provided between the gas-solid separation zone and the multi-stage series reaction zone; The solid particle filling and preheating zone includes an intermediate tank whose top feed port is connected to the discharge channel of the gas-solid separation zone, the top feed port of the intermediate tank is also connected to a solid particle filling line, an intermediate tank heater is wrapped around the outer periphery of the intermediate tank, and a feed control valve corresponding to the feed ports of the multi-stage series reaction zones is provided at the bottom of the intermediate tank.

5. The multi-stage serial fluidized bed reaction system according to claim 1, characterized in that: The multiple series reaction zones are arranged in a straight line from top to bottom, slanting downward or in a Z shape.

6. The multi-stage serial fluidized bed reaction system according to claim 1, characterized in that: The reaction heater adopts a heater with zone heating and temperature control functions.

7. The multi-stage series fluidized bed reaction system according to claim 1, characterized in that: The distributor is located at the junction of the material disperser and the reactor.

8. A method for using the multi-stage series fluidized bed reaction system according to claim 1, characterized in that: The process includes: Process 1: solid particles enter the first segmented reaction zone of the multi-stage series reaction zone, and the reactor in the segmented reaction zone moves downward uniformly, the coating raw material enters the reactor from the distributor through the coating raw material feed line, the upward coating raw material contacts the downward solid particles in reverse to react with the coating, and a coating layer of a certain thickness is formed on the surface of the solid particles; the solid particles coated once enter the storage container along the material disperser, and then enter the loose fluidized state under the action of the fluidized loose wind entering through the loose wind feed line, and are reheated to the temperature required for the secondary coating reaction under the action of the reaction heater; finally, the solid particles enter the second segmented reaction zone of the multi-stage series reaction zone along the plug valve until they flow out of the multi-stage series reaction zone; the gas phase product carrying a small amount of solid particle fine powder in each segmented reaction zone of the multi-stage series reaction zone enters the gas-solid separation zone; wherein, the coating raw materials introduced into each segmented reaction zone of the multi-stage series reaction zone are the same or different; Process 2: The coated particles flowing out of the multi-stage series reaction zone are divided into three routes: the first route is connected to the solid product sampling component, the second route is connected to the product tank, and the third route is connected to the lifting pipe; the coated particles are analyzed by the solid product sampling component. If the analysis is qualified, the lifting air duct is closed, and the qualified coated particles are sent to the product tank along the second route. If the analysis is unqualified, the lifting air duct is opened, and under the action of the lifting air transported through the lifting air duct, the coated particles enter the gas-solid separation zone along the lifting pipe; Process 3: The solid particles separated from the gas-solid separation zone enter the first segmented reaction zone of the multi-stage series reaction zone again for cyclic coating operation.

9. A method for using the multi-stage series fluidized bed reaction system according to claim 2, characterized in that: The process includes: Process 1: solid particles enter the first segmented reaction zone of the multi-stage series reaction zone, and the reactor in the segmented reaction zone moves downward uniformly, the coating raw material enters the reactor from the distributor through the coating raw material feed line, the upward coating raw material contacts the downward solid particles in reverse to react with the coating, and a coating layer of a certain thickness is formed on the surface of the solid particles; the solid particles coated once enter the storage container along the material disperser, and then enter the loose fluidized state under the action of the fluidized loose wind entering through the loose wind feed line, and are reheated to the temperature required for the secondary coating reaction under the action of the reaction heater; finally, the solid particles enter the second segmented reaction zone of the multi-stage series reaction zone along the plug valve until they flow out of the multi-stage series reaction zone; the gas phase product carrying a small amount of solid particle fine powder in each segmented reaction zone of the multi-stage series reaction zone enters the gas-solid separation zone; wherein, the coating raw materials introduced into each segmented reaction zone of the multi-stage series reaction zone are the same or different; Process 2: The coated particles flowing out of the multi-stage series reaction zone are divided into three routes: the first route is connected to the solid product sampling component, the second route is connected to the product tank, and the third route is connected to the lifting pipe; the coated particles are analyzed by the solid product sampling component. If the analysis is qualified, the lifting air duct is closed, and the qualified coated particles are sent to the product tank along the second route. If the analysis is unqualified, the lifting air duct is opened, and under the action of the lifting air transported through the lifting air duct, the coated particles enter the gas-solid separation zone along the lifting pipe; Process three, the gas-solid flow entering the cyclone separator is subjected to gas-solid separation in the corresponding cyclone separator, and the separated solid particles descend along the cyclone separator legs to the bottom of the inner cavity of the lower separation chamber; the gas containing a small amount of solid particle powder ascends from the cyclone separator outlet and enters the upper separation chamber, the gas therein passes through the filter into the gas collecting chamber, and leaves from the exhaust gas outlet line, the solid particle powder intercepted by the filter falls to the bottom of the inner cavity of the upper separation chamber, and the solid particles at the bottom of the lower separation chamber inner cavity and the bottom of the upper separation chamber inner cavity enter the first segmented reaction zone of the multi-stage series reaction zone again from the corresponding discharge channel for cyclic coating operation.

10. The method for using the multi-stage serial fluidized bed reaction system according to claim 8 or 9, characterized in that: The fluidizing loosening wind and lifting wind are inert gases.

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