External-channel-supported double-shaft lime kiln capable of both mixing materials and injecting and production method

Abstract

The present application discloses an externally-channel-supported double-shaft lime kiln for both mixing and injection, and a production method thereof. An extended furnace body structure is adopted. An external circulation flue, an external flue type diagonal support structure, a detachable spray gun, a pneumatic conveying device for ash cleaning of the flue, a waste heat drying, screening and spin suspension preheater at the kiln top, as well as a constant temperature calcination reactor, an electromagnetic induction heating temperature regulation device, etc. are provided on the kiln body. It can realize the conversion of the production functions between a single-shaft vertical kiln and a double-shaft vertical kiln. It can not only be independently used for mixing production with lump solid fuel, but also realize double-shaft heat storage and injection of pulverized fuels such as coal and biomass, and gaseous fuels, and at the same time realize waste heat suspension calcination of powdered lime. It also solves the problems of structural defects, production defects and safety hazards brought by the corbel support and suspension cylinder structure arranged in the furnace of the traditional double-shaft kiln. The solution proposed in the present application is a major innovation and technical improvement of the traditional lime kiln structure and lime production method.

Description

Technical Field

[0001] This application relates to the technical field of industrial vertical kilns, and particularly to a lime kiln for producing lime, specifically an externally-channel-supported double-chamber lime kiln that can achieve dual functions of mixing materials and injection, and a production method for producing lime using the same. Background Art

[0002] Currently, lime is mainly produced through the vertical kiln process. The vertical kiln process is divided into two types: single-chamber vertical kilns and double-chamber vertical kilns. The fuel structure of single-chamber vertical kilns is a mixed-material production process that uses solid lump coal or coke fuel mixed with stone materials for combustion. This production process cannot use pulverized coal and other powdered fuels for production. While double-chamber lime kilns can achieve the injection of coal powder fuels and gas fuels, they cannot use lump solid fuels for production due to process limitations.

[0003] Due to the limitations of the process structure of existing single-chamber mixed-material lime vertical kilns, the fuel varieties selected are single. They can only use expensive high-quality lump anthracite and lump coke, and cannot use low-cost fuels with high volatility such as bituminous coal, lignite, and gas coal. Therefore, this process not only has high fuel costs but also poor quality of lime products. In addition, due to the inability of single-chamber vertical kilns to achieve the heat storage function, the fuel energy consumption has always been higher than that of other kiln types. More importantly, with the development of the economic society, China has gradually phased out and prohibited the construction of single-chamber lime kilns that use solid traditional fossil energy fuels such as coal. Therefore, how to change and improve the production process of traditional single-chamber mixed-material vertical kilns, reduce fuel production costs, improve product quality, and promote the transformation and upgrading of coal for lime fuel selection is of great significance for realizing the green and carbon-reducing upgrade of the lime industry and solving the common bottlenecks in the industry.

[0004] Parallel-flow regenerative double-chamber lime kilns have been widely promoted worldwide due to their unique energy-saving advantages. So far, double-chamber lime vertical kilns have been developed for more than 60 years. The parallel-flow regenerative double-chamber lime kiln has a unique double-chamber structure, and its two chambers can alternately achieve the functions of calcination and heat storage, and can achieve the highest lime activity and the lowest fuel energy consumption. Therefore, it has process advantages that cannot be compared with other lime kilns, especially its ability to use all powdered fuels such as bituminous coal, lignite, and gas coal with high volatility for production.

[0005] Currently, there are mainly two types of double-chamber vertical kilns commonly used at home and abroad: the corbel structure and the hanging cylinder structure. Among them, the corbel support structure of the corbel-type double-chamber kiln is arranged at the lower part of the calcination zone inside the kiln body, and the entire calcination zone and preheating zone of the kiln body are supported by multiple corbel-shaped columns composed of refractory materials.

[0006] (1) Due to the limitations of the corbel structure characteristics, the following disadvantages exist in this structure:

[0007] 1. Because the corbel column feet are set in the furnace, there are multiple dead corners between the corbel columns where air cannot circulate, resulting in poor gas circulation atmosphere in the kiln, and the combustion and cooling effects in the kiln are affected;

[0008] 2. The corbel support parts, arch bridge parts, and the middle layer of refractory materials in the kiln are prone to collapse accidents and collapse due to temperature fluctuations caused by material extrusion or repeated impact of cold air;

[0009] 3. The flue gas circulation channel is seriously ash-accumulated, and the ash accumulation easily forms scabs, nodules and other materials that are difficult to handle. It is necessary to stop production regularly for manual ash removal and nodule removal. Furthermore, because the flue gas channel is set inside the kiln, construction and maintenance are extremely difficult;

[0010] 4. The refractory material has a complex structure, high production requirements, great construction difficulty, large usage, and high investment costs.

[0011] (II) As the second generation technology, the double-chamber kiln suspension cylinder structure overcomes some of the above defects compared to the bull leg support structure, but the existing suspension cylinder technology also has the following defects:

[0012] 1. The structure of the hanging cylinder double-chamber kiln is complex. The hanging cylinder part that bears two-thirds of the weight of the kiln needs to be made of special heat-resistant steel as a whole, which has high production requirements, great production difficulty and high cost;

[0013] 2. The hanging cylinder type fixed structure is difficult to repair and has a high risk of accidents. Once a problem occurs, it is difficult to repair, and in serious cases, the entire structure may collapse.

[0014] 3. The suspension cylinder requires a separate fan to supply air for cooling, which increases power consumption. When a power outage or fan failure occurs, it is easy to cause the cylinder to overheat, affecting the overall service life of the suspension cylinder. When there is a lack of cooling air for a long time, the structure will be burned, which is very likely to cause damage to the cylinder and overall collapse accidents.

[0015] 4. The hanging ring on the hanging cylinder must be made of refractory castables. At the same time, on-site pouring requires formwork support, maintenance, demoulding, and baking, which significantly increases the construction difficulty and construction period.

[0016] It can be seen that the thermal conditions in the traditional double-chamber kiln need to be further improved.

[0017] The thermal engineering principle of lime calcination in a double-shaft lime kiln is through the heat exchange between the solid and gas phases in the air flow among the gaps of stone particles. The condition of the air flow distribution in the kiln directly determines the thermal engineering system of the shaft kiln, and the cleanliness and block size ratio of the limestone entering the kiln determine the air permeability in the kiln. If the screening and cleaning of the stone materials are not thorough, or due to the adhesion of muddy soil to the wet stone materials during the rainy season, dust and powder ash will be generated inside the kiln body, causing the flue gas circulation channels in the kiln to be easily blocked, resulting in unobstructed air flow, uneven temperatures in the two kiln chambers, directly affecting the quality of the finished lime; moreover, after a period of production, the channels are easily blocked, affecting the air flow pressure in the kiln body, requiring manual cleaning, which is time-consuming, laborious, unsafe, and also affects the output. It also causes relatively large damage to the refractory bricks, seriously affecting the service life of the refractory materials.

[0018] In the lime production methods, whether it is a single-shaft mixed firing kiln, a double-shaft kiln or a rotary kiln, these lime kiln types all have the problem of a narrow range of raw stone materials used. The particle size range of limestone used in the lime shaft kiln is 60 - 120 mm, and the particle size range of limestone used in the rotary kiln is 20 - 40 mm. A large amount of small-grained limestone with a particle size less than 20 mm is sold at a low price as stone slag, causing great waste of mineral resources and an increase in the cost of stone mining.

[0019] Nowadays, the lime production method is developing towards energy conservation, waste recycling and comprehensive utilization. Therefore, how to burn the screened inferior products of the limestone used in the lime calcination furnace into quicklime, reduce the production cost of enterprises, generate greater economic benefits and avoid environmental protection problems caused by the abandonment of the screened inferior products is the goal of each lime factory.

[0020] Therefore, based on the current situation of the double-shaft lime kiln, how to solve the defects of the traditional double-shaft shaft kiln; how to organically combine the structural characteristics of the mixed firing single-shaft shaft kiln with the structural characteristics of the double-shaft lime kiln to achieve the integration of the production methods of the two kiln types, and achieve fuel diversification and function diversification; how to transform the traditional mixed material single-shaft shaft kiln into a double-shaft kiln to improve the quality and efficiency of the single-shaft kiln products, and how to burn the screened inferior products of the limestone used in the lime calcination furnace into quicklime to achieve energy conservation and environmental protection while reducing the production cost are the technical problems that need to be solved urgently at present. Summary of the Invention

[0021] This application provides an externally-channel-supported double-shaft lime kiln with dual functions of mixing and injection, to solve the problems of high production cost and relatively low quality of lime production in traditional lime kilns.

[0022] To achieve the above purpose, this application provides the following technical solutions:

[0023] On the one hand, the present application provides an externally fired channel-supported double-shaft lime kiln that can be used for both mixing and injection, including two adjacent vertical kilns. Each vertical kiln includes a kiln body, which has a kiln top, a kiln bottom, a kiln wall, and a kiln chamber. In each kiln chamber, a preheating zone, a calcination zone, and a cooling zone are formed from top to bottom; the preheating zone and the calcination zone are both of straight cylinder type structures, and the cooling zone is of an extended regular cone structure;

[0024] On both kiln tops, there are installed a kiln top combustion-supporting air conversion valve, a kiln top waste gas conversion valve, a two-stage sealed feeding device, and a lifting and rotating composite feeding device;

[0025] On both kiln walls, there are provided a plurality of detachably-mounted spray guns arranged in a ring. The outlet of the detachably-mounted spray gun is arranged at the joint of the bottom of the preheating zone and the upper part of the calcination zone;

[0026] Outside the kiln body at the lower part of each calcination zone, there is provided an external annular flue gas circulation channel. A flue gas control valve is arranged at the tangent part between the external annular flue gas circulation channels on the two kiln bodies;

[0027] In each kiln chamber, there is provided a combustion-supporting air cap,

[0028] At the bottom of each kiln, there is provided an ore discharging system and an ash discharging system. The ore discharging system is used to convey the cooled calcium oxide to the ash discharging system, and the ash discharging system is used to discharge the calcium oxide outside the kiln.

[0029] In the above technical solution, further, the kiln top waste gas conversion valve is connected to the external dust collector pipeline. The two-stage sealed feeding device and the lifting and rotating composite feeding device are used to convey the mixed stone materials and lump coal into the kiln; a manipulator type spreading device is installed on the lifting and rotating composite feeding device, which is used to arrange the large-particle stone materials in the center of the kiln and the small-particle stone materials around the kiln wall.

[0030] Further, on both kiln tops, there are installed kiln top external air inlet pipeline valves.

[0031] Further, a chute type spreading channel is also installed on the lifting and rotating composite feeding device.

[0032] Further, a buffer bin is provided at the top of each kiln. The buffer bin is used to receive the stone materials conveyed by an external elevator. A fixed screening device and a preheating and drying device are arranged inside the buffer bin at the top of the kiln. The fixed screening device at the top of the kiln is used to perform secondary screening on the stone materials. The lower part of the fixed screening device at the top of the kiln is connected to a sieve-through material collection bin. The outlet of the sieve-through material collection bin is connected to a compound crushing device. The outlet of the compound crushing device is connected to a single-cylinder spinning suspension preheater. The outlet of the single-cylinder spinning suspension preheater is connected to a powder suspension calcination channel. A number of baffle plates are arranged inside the powder suspension calcination channel. The outlet of the powder suspension calcination channel is connected to a double-cylinder spinning suspension preheater. The outlet of the double-cylinder spinning suspension preheater is connected to a constant-temperature calcination reactor. The constant-temperature calcination reactor is connected to the exhaust gas outlet pipe of the powder release bin. The constant-temperature calcination reactor performs constant-temperature flash calcination on the lime powder through the high-temperature exhaust gas fed into it, and decomposes the lime powder into active lime.

[0033] Further, an electromagnetic induction heating temperature regulating device is arranged on the exhaust gas outlet pipe of the powder release bin. The electromagnetic induction heating temperature regulating device is used to heat the exhaust gas discharged from the powder release bin to a set temperature, and the exhaust gas heated to the set temperature is fed into the constant-temperature calcination reactor.

[0034] Further, the external annular flue gas circulation channel is fixed on the kiln wall through an inclined flue gas duct support structure arranged below it. The inclined flue gas duct support structure is an external flue gas duct inclined support channel, and a plurality of external flue gas duct inclined support channels are communicated with the external annular flue gas circulation channel.

[0035] Further, the external annular flue gas circulation channel is communicated with the powder suspension calcination channel through a flue gas circulation channel pressure regulating and releasing valve.

[0036] Further, a circulating flue gas ash collection bin is arranged between two external flue gas duct inclined support channels. The lower outlet of the circulating flue gas ash collection bin is communicated with an annular ash cleaning pneumatic conveying pipeline. A pulse ash discharging valve is arranged on the pipeline used to connect the circulating flue gas ash collection bin and the annular ash cleaning pneumatic conveying pipeline.

[0037] Further, the annular ash cleaning pneumatic conveying pipeline is connected to an external ash cleaning pneumatic conveying pipeline, and the external ash cleaning pneumatic conveying pipeline is connected to the powder release bin. A cyclone dust removal and filtration device is arranged in the powder release bin. The cyclone dust removal and filtration device is used to separate dust from flue gas. The separated dust descends and falls into the lower ash hopper, and the separated flue gas ascends and enters the powder suspension calcination channel through a pressure release regulating device.

[0038] Further, the annular ash cleaning pneumatic conveying pipeline is connected to an internal ash cleaning pneumatic conveying pipeline, and the internal ash cleaning pneumatic conveying pipeline is used to discharge the dust materials outside the kiln.

[0039] Further, the ore discharge system includes a plurality of peripheral discharge devices evenly arranged circumferentially along the kiln wall, and a central discharge device arranged at the center of the plurality of peripheral discharge devices.

[0040] Further, the ash discharge system includes a directional rotary ash discharge device and a metering device. The discharge pipes of the peripheral discharge devices and the discharge pipes of the central discharge device are both connected to the directional rotary ash discharge device, and the directional rotary ash discharge device is used to feed calcium oxide into a plurality of metering devices; the metering device is connected to the furnace bottom ash discharge bin, and the furnace bottom ash discharge bin is connected to a multi-stage sealed discharger, and the multi-stage sealed discharger is used to discharge the metered calcium oxide out of the kiln body.

[0041] Further, from the bottom of the calcination zone to the bottom of the cooling zone, the inner diameter of the kiln chamber gradually expands.

[0042] Further, each kiln bottom is provided with an air inlet, and a kiln bottom cooling air conversion valve is arranged on the air inlet.

[0043] Further, a combustion-supporting air cap is arranged in each kiln chamber. The combustion-supporting air cap is located at the kiln bottom and above the ore discharge system.

[0044] On the other hand, the present application provides a production method for producing lime by using the above-mentioned dual-purpose mixing and injection external-channel-supported double-shaft lime kiln. The production method realizes the switching between the mixing production process and the process of injecting pulverized coal and gaseous fuel by switching the opening and closing states of the flue gas control valves arranged between two external annular flue gas circulation channels.

[0045] In the above technical solution, further, closing the flue gas control valve to realize the mixing production process specifically includes the following steps:

[0046] S1: Close the flue gas control valve so that each kiln chamber forms an independent flue gas circulation system. For any one vertical kiln, close its kiln top combustion-supporting air conversion valve and open the kiln top waste gas conversion valve, and a negative pressure is formed in the kiln chamber;

[0047] S2: The mixture of stone and lump coal is conveyed into the kiln by a two-stage sealed feeding device and a lifting rotary composite feeder;

[0048] S3: When the materials in the kiln drop to the calcination zone position, the combustion-supporting air from the combustion-supporting air cap burns with the fuel in the stone, and the CO in the stone 2 decomposes to form calcium oxide;

[0049] S4: When the calcium oxide continues to drop to the lower part of the calcination zone, it exchanges heat and cools with the combustion-supporting air from the kiln bottom. The heat-exchanged combustion-supporting air continues to rise to the calcination zone to participate in combustion; after the combustion exhaust gas passes through the preheating zone and exchanges heat with the stone, the temperature of the exhaust gas drops and is discharged out of the kiln through the kiln top waste gas conversion valve;

[0050] S5: After the calcium oxide continues to descend to the lower space of the combustion air tuyere at the bottom of the kiln, the entire cooling process is completed, and then it enters the ore discharge system and the ash discharge system in sequence, and is discharged outside the kiln by the ash discharge system.

[0051] Furthermore, denote the two vertical kilns as Kiln A and Kiln B respectively, denote the kiln chamber of Kiln A as Chamber A, and denote the kiln chamber of Kiln B as Chamber B; Open the flue gas control valve to implement the production process of injecting pulverized coal and gaseous fuel, which specifically includes the following steps:

[0052] S1: Open the flue gas control valve to enable the waste gas in Chamber A and Chamber B to flow through each other.

[0053] S2: Open the combustion air conversion valve at the top of Kiln A and blow high-pressure combustion air into the preheating zone of Chamber A to make the calcination zone in a positive pressure state.

[0054] S3: Convey pulverized coal fuel or gaseous fuel into Chamber A through a detachable spray gun, and mix it with the high-pressure combustion air flowing from top to bottom to form a hot combustion flame. The combustion flame penetrates the calcination zone to form a high-temperature zone in the calcination zone. The stone materials conduct heat exchange in the high-temperature zone of the calcination zone. During the heat exchange process, the flame and the stone materials move in the same direction to complete the co-current calcination process; During this process, the stone materials decompose to form calcium oxide.

[0055] S4: The calcium oxide slowly descends to the position of the external annular flue gas circulation channel, intersects with the counter-current cooling air flowing from bottom to top generated by the combustion air tuyere at the bottom of the kiln, and forms a positive pressure air flow. The air flow after intersection flows into the external annular flue gas circulation channel.

[0056] S5: During the same time period when the operations in steps S1 - S4 are completed in Chamber A, the following steps are carried out in Chamber B: Close the combustion air conversion valve at the top of the kiln; Stop the fuel supply of the detachable spray gun on it; Open the waste gas conversion valve at the top of the kiln and connect it to the external dust collector pipeline, and make the entire Chamber B in a negative pressure heat storage state under the action of the external dust collector; Due to the pressure difference between Chamber A and Chamber B, the high-temperature waste heat flue gas inside the external annular flue gas circulation channel of Kiln A quickly flows into Chamber B, converges with the high-pressure combustion air in Chamber B, and forms a new positive pressure air flow, so that the high-temperature waste gas in Chamber A and the stone materials in Chamber B penetrate the entire calcination zone and preheating zone from bottom to top for sufficient heat exchange to complete counter-current heat storage; The flue gas after heat storage is discharged outside the kiln through the waste gas conversion valve at the top of the kiln and enters the external dust collector.

[0057] In the above operation steps, the commutation time of Chamber A and Chamber B is set artificially, and Chamber A and Chamber B commutate for calcination according to the set commutation time, and repeat the above operation steps.

[0058] Furthermore, the suspension calcination process of powdered lime can be achieved under both the mixed material production process and the pulverized coal and gas fuel injection production process. The suspension calcination process of powdered lime includes: a buffer bin is arranged at the top of each kiln, a fixed screening device and a preheating and drying device are arranged inside the buffer bin, the fixed screening device at the kiln top is connected to a compound crushing device, the outlet of the compound crushing device is connected to a single-cylinder spinning suspension preheater, the outlet of the single-cylinder spinning suspension preheater is connected to a powdered material suspension calcination channel, the powdered material suspension calcination channel is connected to a double-cylinder spinning suspension preheater, the outlet of the double-cylinder spinning suspension preheater is connected to a constant-temperature calcination reactor, the constant-temperature calcination reactor is connected to the exhaust gas outlet pipe of the powdered material release bin, and an electromagnetic induction heating temperature control device is arranged on the exhaust gas outlet pipe of the powdered material release bin;

[0059] The screened stone powder and coal particle fuel are crushed to the target particle size for suspension calcination by the compound crushing device;

[0060] The mixed powder of the crushed stone material and fuel enters the single-cylinder spinning suspension preheater and the double-cylinder spinning suspension preheater in sequence through the powdered material suspension calcination channel, and finally enters the constant-temperature calcination reactor, and is decomposed and calcined with the exhaust gas from the powdered material release bin to generate active lime.

[0061] Compared with the prior art, the present application has the following beneficial effects:

[0062] The present application provides an externally-channel-supported double-chamber lime kiln that can be used for both mixing and injection. A flue gas control valve is arranged inside the flue between the two kiln chambers to realize the opening and closing of the waste heat flue gas between the two kiln chambers, achieving the independent production function of a single-chamber kiln during the mixed material production and the heat storage function of the flue gas intercommunication between the two kiln bodies during the double-chamber regenerative production; and a detachable spray gun is provided to facilitate the process adjustment when using different fuel structures; the externally-channel-supported double-chamber lime kiln provided by the present application changes the production method of the traditional single-chamber mixed material lime shaft kiln that can only use a single type of solid fuel such as lump anthracite or coke, and can use pulverized bituminous coal and biomass powder fuel with low injection cost, reducing the cost and realizing the benefit improvement; the externally arranged annular flue gas circulation channel makes the kiln body structure more reasonable and safe, and the extended positive conical structure is adopted for the cooling zone inside the kiln, making the waste heat flue gas flow direction in the calcination zone and the cooling zone more reasonable, and making the material cooling time in the cooling zone more sufficient and the lime activity higher. Description of the Drawings

[0063] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. It should be understood that the specific shapes and structures shown in the drawings generally should not be regarded as limiting conditions when implementing the present application; for example, those skilled in the art are capable of making routine adjustments or further optimizations to the addition / removal / attribution division of certain units (components), specific shapes, positional relationships, connection methods, dimensional proportional relationships, etc. based on the technical concepts disclosed in the present application and the exemplary drawings.

[0064] Figure 1 It is a schematic structural diagram of a bracket-type double-shaft kiln;

[0065] Figure 2 It is a schematic structural diagram of a suspension-cylinder double-shaft kiln;

[0066] Figure 3 It is a schematic diagram of the structural principle of an externally-channel-supported double-shaft lime kiln when carrying out a mixing production process by using the externally-channel-supported double-shaft lime kiln provided by the present application in an embodiment. The arrows in the figure indicate the air flow direction;

[0067] Figure 4 From Figure 3 It is a display diagram of a partial drawing intercepted from the upper part;

[0068] Figure 5 From Figure 3 It is a display diagram of a partial drawing intercepted from the middle part;

[0069] Figure 6 From Figure 3 It is a display diagram of a partial drawing intercepted from the lower part;

[0070] Figure 7 It is a schematic diagram of the structural principle of an externally-channel-supported double-shaft lime kiln when carrying out a pulverized coal and gas fuel injection production process by using the externally-channel-supported double-shaft lime kiln provided by the present application in another embodiment. The arrows in the figure indicate the air flow direction;

[0071] Figure 8 From Figure 7 It is a display diagram of a partial drawing intercepted from the upper part;

[0072] Figure 9 From Figure 7 It is a display diagram of a partial drawing intercepted from the middle part;

[0073] Figure 10 From Figure 7 It is a display diagram of a partial drawing intercepted from the lower part;

[0074] Figure 11 It is a schematic diagram of a ring-shaped ash-removing pneumatic conveying pipeline and some related structures arranged on an externally-channel-supported double-chamber lime kiln provided in an embodiment of the present application.

[0075] Explanation of reference numerals:

[0076] 1. Combustion-supporting air conversion valve at the kiln top; 2. Waste gas conversion valve at the kiln top; 3. Two-stage sealed feeding device; 4. Lifting and rotating composite feeding device; 4-1. Manipulator-type material spreading device; 4-2. Chute-type material spreading channel; 5. Detachable spray gun; 6. External ring-shaped flue gas circulation channel; 7. External flue-type inclined support channel; 8. Flue gas control valve; 9. Ash collection bin for the circulating flue; 10. Pulse ash discharge valve; 11. Ring-shaped ash-removing pneumatic conveying pipeline; 12. External connection pipeline for ash-removing pneumatic conveying; 13. Internal connection pipeline for ash-removing pneumatic conveying; 14. Combustion-supporting air cap; 15. Peripheral discharging device; 16. Central discharging device; 17. Directional rotating ash discharging device; 18. Measuring device; 19. Multi-stage sealed discharging device; 20. Waste gas surrounding pipe; 21. Buffer bin; 22. Fixed screening device at the kiln top; 23. Sieve residue collection bin; 24. Pressure regulating and releasing valve for the flue gas circulation channel; 25. Powder suspension calcination channel; 25-1. Baffle plate; 26. Composite crushing device; 27. Single-cylinder spin suspension preheater; 28. Powder release bin; 29. Pressure release and regulating device; 30. Waste gas branch pipe; 31. Double-cylinder spin suspension preheater; 32. Constant-temperature calcination reactor; 33. Electromagnetic induction heating temperature regulating device; 34. Flue gas nozzle I; 35. Flue gas nozzle II. Detailed implementation manners

[0077] The following further details the present application through specific embodiments in conjunction with the accompanying drawings.

[0078] In the description of the present application: Unless otherwise specified, "a plurality of" means two or more. Terms such as "first", "second", "third", etc. in the present application are intended to distinguish the objects being referred to, and do not have special meanings in terms of technical connotations (for example, they should not be understood as emphasizing importance levels or orders, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0079] Terms such as "upper", "lower", "left", "right", "middle", etc. cited in the present application are usually for facilitating intuitive understanding with reference to the accompanying drawings, and are not absolute limitations on the positional relationships in actual products. Without departing from the technical concept disclosed in the present application, changes in these relative positional relationships should also be regarded as within the scope of the present application's description.

[0080] Embodiment 1

[0081] To solve the problems existing in the prior art, the present application provides an externally-channel-supported double-shaft lime kiln that can be used for both mixing and injection (hereinafter referred to as the externally-channel-supported double-shaft lime kiln). This externally-channel-supported double-shaft lime kiln is an active lime production device that can realize the production function conversion between a single-shaft vertical kiln and a double-shaft vertical kiln.

[0082] The externally-channel-supported double-shaft lime kiln provided by the present application is a new type of double-shaft vertical kiln. Through measures such as an external circulation flue, an external flue-type diagonal support structure, a detachable spray gun device, an extended furnace body structure, a flue control valve, a fully automatic external flue ash cleaning pneumatic conveying device, a multi-point rotary weighing ash discharging system, waste heat drying, screening and suspension calcination of powder at the kiln top, etc., it not only realizes the purpose of using block solid fuel independently for mixing production, but also realizes the purpose of double-shaft heat storage and injecting powdered fuel (such as coal, biomass, etc.) and gaseous fuel (such as industrial waste gas, biomass gas, natural gas, etc.) to produce highly active lime, and also realizes the purpose of waste heat suspension calcination of powdered lime.

[0083] In addition, the externally-channel-supported double-shaft lime kiln provided by the present application also solves key problems such as structural defects, production defects, and potential safety hazards caused by the internal corbel support and suspension cylinder structure in traditional double-shaft kilns.

[0084] To highlight the differences between the solution proposed in the present application and traditional double-shaft vertical kilns, the following combines Figure 1 and Figure 2 to illustrate the structural principle of traditional double-shaft vertical kilns.

[0085] Figure 1 Figure 17 is a schematic structural diagram of a corbel-type double-shaft kiln. As can be seen from the figure, two kiln shafts are arranged in parallel, where: at a1 is the internal corbel support part of the kiln. Inside the kiln body, several support structures made of refractory bricks are evenly distributed in a ring to support the kiln body structure in the preheating zone and calcination zone of the whole kiln body. At a2 is the internal annular flue gas channel for connecting the flue gas intercommunication of the two kiln shafts. At a3 are poking holes, and several are arranged above the annular channel for manual ash cleaning. At a4 is a fixed ash discharging device that discharges ash by means of parallel micro-movement. At a5 is a manual tumor cleaning manhole device, and several are arranged outside the kiln body for manual cleaning when the fixed ash discharging device at a4 cannot remove large block material nodules due to small movement. At a6 is an air cannon, and high-pressure air is required to clean the internal accumulated ash at a2 during production.

[0086] Figure 2It is a schematic structural diagram of a suspension cylinder type double-chamber kiln. As can be seen from the figure, there are two kiln chambers arranged in parallel, where: at b1 is the position of the suspension cylinder inside the furnace. Inside the kiln body, the kiln shell in the calcination zone is connected to the upper annular suspension of the annular channel, suspending the kiln body structure of the preheating zone and the calcination zone of the entire kiln body. Special high-pressure blowers are required for ventilation and cooling inside the suspension cylinder. At b2 is the annular flue gas channel inside the kiln, used for the interconnection of flue gases between the two kiln chambers. At b3 are the poking holes, several of which are arranged above the annular channel, used for manual ash cleaning. At b4 is the fixed ash discharging device, which discharges ash by means of parallel micro-movement. At b5 are the manual tumor cleaning manhole devices, several of which are arranged outside the kiln body, used for manual cleaning when the fixed ash discharging device at b4 cannot remove large pieces of material nodules due to the small movement amount. At b6 are the air cannons, and high-pressure air is required for cleaning the accumulated ash inside b2 during production.

[0087] It can be seen from Figure 1 and Figure 2 that in the traditional double-chamber kiln structure, whether it is the bracket type structure or the suspension cylinder structure, they are both arranged inside the furnace, and the annular flue gas channel requires air cannons for ash cleaning and manual ash cleaning during regular shutdowns. The accumulated ash cleaned still falls inside the kiln and cannot be cleaned outside the kiln, and the key problems such as the easy sintering into blocks and nodulation caused by the long-term retention of the accumulated ash in the high-temperature zone of the flue gas circulation channel have not been fundamentally solved. Moreover, the ash discharging device is fixed and cannot rotate to discharge ash, resulting in the inability to remove large pieces of material, and the material surface inside the kiln cannot be adjusted either.

[0088] The structural principle of the double-chamber lime kiln with an external channel support provided in the present application will be described in detail below with reference to the accompanying drawings.

[0089] The double-chamber lime kiln with an external channel support provided in the present application includes two adjacent vertical kilns. Each vertical kiln includes a kiln body, and the kiln body has a kiln top, a kiln bottom, a kiln wall, and a kiln chamber. In each kiln chamber, a preheating zone, a calcination zone, and a cooling zone are formed from top to bottom; the preheating zone and the calcination zone are both of straight cylinder type structures, and the cooling zone is of an extended regular cone structure, and the inner diameter of the kiln chamber gradually expands from the bottom of the calcination zone to the bottom of the cooling zone. On both kiln tops, there are a kiln top combustion-supporting air conversion valve 1, a kiln top waste gas conversion valve 2, a two-stage sealed feeding device 3, a lifting and rotating composite feeding device 4, and a kiln top external air inlet pipe valve. On both kiln walls, there are multiple detachably mounted spray guns 5 arranged in a ring. The outlet of the detachably mounted spray gun 5 is arranged at the joint of the bottom of the preheating zone and the upper part of the calcination zone. Outside the kiln body at the lower part of each calcination zone, there is an external annular flue gas circulation channel 6, and a flue gas control valve 8 is arranged at the tangent part between the external annular flue gas circulation channels 6 on the two kiln bodies. In each kiln chamber, there is a combustion-supporting air cap 14. At each kiln bottom, there is a ore discharging system and an ash discharging system. The ore discharging system is used to convey the cooled calcium oxide to the ash discharging system, and the ash discharging system is used to discharge the calcium oxide outside the kiln.

[0090] The waste gas conversion valve 2 at the kiln top in this application is connected to the external dust collector pipeline. The two-stage sealed feeding device 3 and the lifting and rotating composite feeding device 4 are used to convey the mixed stone materials and lump coal into the kiln. A manipulator-type spreading device 4-1 is installed on the lifting and rotating composite feeding device 4, which is used to arrange large-particle stone materials in the center of the kiln and small-particle stone materials around the kiln wall. A chute-type spreading channel 4-2 is also installed on the lifting and rotating composite feeding device 4.

[0091] A buffer bin 21 is provided at each kiln top. The buffer bin 21 is used to receive the stone materials conveyed by the external elevator. A kiln top fixed screening device 22 and a preheating and drying device are arranged inside the buffer bin 21 at the kiln top. The kiln top fixed screening device 22 is used to perform secondary screening on the stone materials. The lower part of the kiln top fixed screening device 22 is connected to the undersize collecting bin 23. The outlet of the undersize collecting bin 23 is connected to the compound crushing device 26. The outlet of the compound crushing device 26 is connected to the single-cylinder spinning suspension preheater 27. The outlet of the single-cylinder spinning suspension preheater 27 is connected to the powder suspension calcination channel 25. A number of baffle plates 25-1 are arranged in the powder suspension calcination channel 25.

[0092] The powder suspension calcination channel 25 is connected to the double-cylinder spinning suspension preheater 31. The outlet of the double-cylinder spinning suspension preheater 31 is connected to the constant-temperature calcination reaction kettle 32. The constant-temperature calcination reaction kettle 32 is connected to the waste gas outlet pipe of the powder release bin 28. The constant-temperature calcination reaction kettle 32 performs constant-temperature flash calcination on the lime powder through the high-temperature waste gas fed into it, decomposing the lime powder into active lime. Among them: an electromagnetic induction heating temperature regulating device 33 is arranged on the waste gas outlet pipe of the powder release bin 28. The electromagnetic induction heating temperature regulating device 33 is used to heat the waste gas discharged from the powder release bin 28 to the set temperature, and the waste gas heated to the set temperature is fed into the constant-temperature calcination reaction kettle 32.

[0093] The external annular flue gas circulation channel 6 is fixed on the kiln wall through the external flue duct type inclined support channel 7 arranged below it. A plurality of external flue duct type inclined support channels 7 are communicated with the external annular flue gas circulation channel 6. The external annular flue gas circulation channel 6 is communicated with the powder suspension calcination channel 25 through the flue gas circulation channel pressure regulating and releasing valve 24.

[0094] A circulating flue dust collecting bin 9 is arranged between two external flue duct type inclined support channels 7. The lower outlet of the circulating flue dust collecting bin 9 is communicated with the annular dust cleaning pneumatic conveying pipeline 11. A pulse-type ash discharging valve 10 is arranged on the pipeline connecting the circulating flue dust collecting bin 9 and the annular dust cleaning pneumatic conveying pipeline 11.

[0095] The annular dust-removing pneumatic conveying pipeline 11 is connected to the external dust-removing pneumatic conveying pipeline 12, and the external dust-removing pneumatic conveying pipeline 12 is connected to the powder release bin 28; a cyclone dust removal and filtration device is arranged in the powder release bin 28, and the cyclone dust removal and filtration device is used to separate dust and flue gas; the separated dust descends and falls into the lower ash hopper, and the separated flue gas ascends and enters the powder suspension calcination channel 25 through the pressure release and adjustment device 29; the annular dust-removing pneumatic conveying pipeline 11 is connected to the internal dust-removing pneumatic conveying pipeline 13, and the internal dust-removing pneumatic conveying pipeline 13 is used to discharge the dust material outside the kiln.

[0096] The ore discharging system in the present application includes a plurality of peripheral discharging devices 15 evenly arranged circumferentially along the kiln wall, and a central discharging device 16 arranged at the center of the plurality of peripheral discharging devices 15.

[0097] The ash discharging system in the present application includes a directional rotation ash discharging device 17 and a metering device 18. The feeding pipes of the peripheral discharging devices 15 and the feeding pipes of the central discharging device 16 are both communicated with the directional rotation ash discharging device 17, and the directional rotation ash discharging device 17 is used to feed calcium oxide into the plurality of metering devices 18; the metering device 18 is connected to the furnace bottom ash discharging bin, and the furnace bottom ash discharging bin is connected to a multi-stage sealed discharging device 19, and the multi-stage sealed discharging device 19 is used to discharge the metered calcium oxide out of the kiln body.

[0098] 1. The externally supported double-chamber lime kiln provided in the present application is provided with an independent annular flue gas channel outside the kiln shell at the lower part of the calcination zone inside the kiln. The outer shell of the annular flue gas channel is connected to the furnace body shell by steel, and refractory materials are laid inside. The annular flue gas channels between the two kiln chambers are interconnected.

[0099] 2. The annular flue gas channel on the kiln body is connected to the flue gas inside the kiln, and is structurally supported by several independent inclined flue duct type support structures. The outer shell of the inclined flue duct type support structure is connected to the annular flue gas channel and the kiln shell by steel structures, and refractory materials are laid inside. Each inclined flue duct type support structure is hollow inside.

[0100] 3. The preheating zone and the calcination zone on the kiln body adopt a straight cylinder type structure, and refractory materials are laid inside to meet the process requirements for producing lime by the mixed material method; the cooling zone on the kiln body adopts an extended regular cone steel structure, and refractory materials are laid inside to meet the process requirements for the production of a double-chamber kiln body.

[0101] 4. Heat-resistant control valves are arranged at the tangent parts between the annular flue gas channels on the two kiln bodies. When the double-chamber kiln body is used for production, the valves are opened to realize the interconnection of the flue gas in the two kiln chambers and adjust the flue gas flow; when the mixed material method is used for production, the valves are closed to block the interconnection of the flue gas in the two kiln chambers and realize single-chamber mixed material production.

[0102] 5. A circulating flue ash bin is arranged between every two diagonal flue - type support structures at the lower part of the external annular flue gas circulation channel. Refractory materials are laid or cast inside the circulating flue ash bin, and a valve or a feeding device is arranged at the lower outlet of the circulating flue ash bin and connected to the annular pneumatic conveying pipeline.

[0103] 6. An ash discharging system is arranged on the kiln body, including a unidirectional rotary ash discharging device and a metering device. The ash discharging system is a multi - point rotary weighing ash discharging system, which can convey materials to the inside of the weighing device through a rotary mechanism to accurately control the ash discharging amount and adjust the furnace condition.

[0104] 7. A portable detachable spray gun is arranged in the pre - heating zone of the kiln body. The outlet of the spray gun is arranged at the combined part of the bottom of the pre - heating zone and the upper part of the calcination zone, so as to achieve the purpose of injecting solid powdered fuel and gaseous fuel during the production of the double - chamber kiln; the structure of the spray gun is detachable, and the spray gun can be conveniently disassembled when mixed - material production is adopted.

[0105] 8. A fixed screening device 22 and a pre - heating and drying device are arranged inside the buffer bin 21 at the kiln top to screen the stone materials for the second time. The screened fine powder directly enters the compound crushing device 26 for fine crushing; a single - cylinder spin - flash pre - heater 27 is arranged below the compound crushing device 26 for primary pre - heating and decomposition, so that the decomposition temperature of the lime fine powder reaches above 300 °C; a double - cylinder spin - flash pre - heater 31 is arranged below the single - cylinder spin - flash pre - heater 27 for secondary pre - heating and decomposition, so that the decomposition temperature of the lime fine powder reaches above 800 °C; a constant - temperature calcination reactor 32 is arranged below the double - cylinder spin - flash pre - heater 31, and the waste gas at about 600 - 700 °C from the waste gas circulation channel of the lime kiln body is used to carry out constant - temperature flash calcination on the lime powder, and the lime powder is decomposed into active lime within 1 second.

[0106] 9. An electromagnetic induction heating temperature - regulating device 33 is arranged on the waste gas outlet pipeline of the powder release bin 28 to heat the waste gas at about 600 - 700 °C released from the powder release bin 28 to about 1100 °C and convey it into the constant - temperature calcination reactor 32 to increase the temperature, so as to achieve the purpose of constant - temperature flash calcination; the electromagnetic induction heating temperature - regulating device 33 has the function of regulating the temperature, so that the temperature of the constant - temperature calcination reactor 32 is adjustable and can be kept constant within a temperature range.

[0107] The advantages of the externally - channel - supported double - chamber lime kiln provided by this application will be described in detail from the aspects of structure and function below.

[0108] 1. The externally-channel-supported double-shaft lime kiln provided by this application is equipped with an external waste heat flue gas circulation channel, making the kiln body structure more reasonable and safer. The external flue is supported diagonally, enabling uniform distribution of combustion and flue gas circulation inside the kiln without dead ends. For the cooling zone inside the kiln, an extended furnace body structure is adopted. Starting from the bottom of the calcination zone of the kiln body, the diameter of the kiln body gradually expands, making the flow direction of the waste heat flue gas in the calcination zone and the cooling zone more reasonable, and allowing for more sufficient cooling time of the materials in the cooling zone and higher lime activity.

[0109] 2. The externally-channel-supported double-shaft lime kiln provided by this application is provided with several dust removal devices at the lower part of the flue gas circulation channel outside the kiln body. The pneumatic conveying method is used to achieve the conveying and transfer of dust, solving the problems of high-pressure dust cleaning with air cannons and regular shutdown for manual dust cleaning in traditional double-shaft kilns.

[0110] 3. The externally-channel-supported double-shaft lime kiln provided by this application adopts a multi-point rotary weighing ash discharging method, achieving multi-point discharging and material weighing, and enabling adjustment and weighing of different ash discharging amounts in different production processes.

[0111] 4. The externally-channel-supported double-shaft lime kiln provided by this application is equipped with a device for realizing screening at the kiln top and equalizing pressure and drying of flue gas, achieving automatic secondary screening of stones at the kiln top, drying and preheating with some waste gas from the flue gas circulation channel, not only achieving the purpose of equalizing pressure of flue gas, but also making the screening effect more obvious.

[0112] 5. The externally-channel-supported double-shaft lime kiln provided by this application also has the function of suspending the calcination of small-particle stones. A stone powder and fine powder crushing device, namely the compound crushing device 26, is provided at the furnace top. It can crush the stone powder after screening at the kiln top to less than 1 mm, and conduct suspended heat exchange calcination with flue gas waste gas in the constant-temperature calcination reactor 32, directly converting the powder into lime powder (calcium oxide powder), achieving the purpose of energy conservation and waste heat utilization.

[0113] 6. The externally-channel-supported double-shaft lime kiln provided by this application is provided with multiple dust removal devices at the lower part of the external annular flue gas circulation channel 6 of the kiln body. The waste heat flue gas released after pneumatically conveying the dust is reheated by electromagnetic induction, raising the temperature of the waste gas to the decomposition temperature of lime powder during suspended combustion, and recycling the waste heat of the waste gas for lime production, achieving energy conservation and emission reduction.

[0114] 7. The externally-channel-supported double-shaft lime kiln provided by this application is provided with a flue gas control valve inside the flue between the two kiln shafts, realizing the opening and closing of the waste heat flue gas between the two kiln shafts, achieving the independent production function of a single-shaft kiln during mixed-material production and the heat storage function of flue gas intercommunication between the two kiln bodies during double-shaft regenerative production. Moreover, a portable and detachable spray gun is adopted, facilitating process adjustment when using different fuel structures.

[0115] Example 2

[0116] By using the externally-channel-supported double-shaft lime kiln provided in the present application, it is possible to achieve the functional conversion and interchange between the mixed-material single-shaft countercurrent heat exchange production process and the double-shaft co-current calcination countercurrent heat storage production process. The implementation method of the mixed-material production process will be described below.

[0117] The process principle of the mixed-material production process is as follows:

[0118] First, close the isolation valve (i.e., the flue gas control valve 8) at the intermediate interconnection part between the flue gas channels of the two kiln shafts, so that each kiln shaft forms an independent flue gas circulation system, and each individual kiln shaft can operate independently. Then, open the external air intake pipe at the kiln top (connected to the flue gas dust collector at the kiln top) to make the preheating zone inside each independent kiln shaft in a negative pressure state.

[0119] After the stone materials and solid bulk fuels (anthracite or coke with a particle size of 20 mm to 40 mm) are mixed, they enter the preheating zone at the upper part of the kiln. When the stone materials in the preheating zone slowly descend to the upper part of the calcination zone in the furnace, the stone materials reach an initial decomposition temperature of above 890 °C. When the initially decomposed stone materials slowly descend to the middle part of the calcination zone in the furnace, the stone materials reach a temperature of above 1100 °C at which they can be completely decomposed. In this area, carbon dioxide in the limestone can be fully decomposed and released, and the limestone is decomposed into calcium oxide (lime). The decomposed calcium oxide slowly descends to the lower part of the calcination zone in the furnace and exchanges heat with the high-pressure cooling air input from the air inlet at the kiln bottom. Due to the high pressure of the cooling air, the hot air at about 400 - 600 °C after heat exchange rises to the calcination zone to participate in combustion to realize heat energy utilization, so that the temperature of the calcination zone is stabilized within the optimal limestone decomposition temperature range of 1000 - 1200 °C. The calcium oxide (lime) in the cooling zone slowly descends to the lower part of the cooling zone during the cooling process, and after cooling to the range of 50 - 150 °C, it enters the ore discharge system.

[0120] The ore discharge system is arranged at the furnace bottom (i.e., the kiln bottom). The ore discharge system includes a plurality of peripheral discharge bins evenly distributed along the perimeter of the kiln wall and a discharge bin at the furnace center. The calcium oxide (lime) discharged after cooling descends through the peripheral and central feeding pipes to the upper surface of the unidirectional rotary ash discharge device, and then the calcium oxide is discharged through rotation into a plurality of metering devices. After metering, the calcium oxide is discharged into the furnace bottom ash discharge bin through the discharge controller, and the material is discharged out of the furnace by a two-stage sealed discharge device.

[0121] The specific operation process of implementing the mixed-material production process by using the externally-channel-supported double-shaft lime kiln provided in the present application is as follows:

[0122] ① Close the flue gas control valve 8 to make each kiln shaft form an independent and normally operating flue gas circulation system;

[0123] ② Close the combustion air conversion valve 1 at the kiln top, open the waste gas conversion valve 2 at the kiln top to connect with the external dust collector pipeline, and form a negative pressure inside the kiln under the action of the dust collector induced draft fan;

[0124] ③ After mixing the stone materials and lump coal externally, they are transported into the kiln through the internal channels of the two-stage sealed feeding device 3 and the lifting and rotating composite distributing device 4, and uniform distribution of materials inside the kiln is achieved through the lifting device and rotating device of the lifting and rotating composite distributing device 4; Among them: A manipulator type spreading device 4-1 is installed on the lifting and rotating composite distributing device 4, which can arrange large particle stone materials in the center of the kiln and small particle stone materials around the kiln wall;

[0125] ④ The materials inside the kiln slowly descend under the action of the ash discharging device at the kiln bottom. When descending to the calcination zone position, the combustion air from the combustion air cap 14 burns with the fuel in the stone materials, forming an optimal limestone decomposition temperature space body in the range of 1000 - 1200 °C throughout the calcination zone, enabling the CO in the limestone 2 to be rapidly decomposed to form calcium oxide (lime);

[0126] ⑤ When the calcium oxide continues to slowly descend to the lower part of the calcination zone, it exchanges heat and cools with the combustion air from the kiln bottom. The heat-exchanged combustion air continues to rise to the calcination zone to participate in combustion; After the combustion waste gas passes through the preheating zone and fully exchanges heat with the stone materials, the waste gas temperature drops to the range of 120 - 200 °C and is discharged out of the kiln through the waste gas conversion valve 2 at the kiln top and enters the dust removal system;

[0127] ⑥ When the calcium oxide descends to the lower space of the combustion air cap 14 at the kiln bottom, the entire cooling process is completed, cooling the calcium oxide to the range of 50 - 150 °C, and then entering the peripheral discharging device 15 and the central discharging device 16; Through the rotation of the directional rotary ash discharging device 17, the materials are discharged into the metering device 18 at a fixed point; The descending speed of the materials inside the entire kiln depends on the rotation speed of the directional rotary ash discharging device 17 and the set ash discharge amount of the metering device 18; The weighed calcium oxide is discharged out of the kiln through the multi-stage sealed discharging device 19.

[0128] Compared with the traditional mixing production method, the mixing production method using the external channel supported double-chamber lime kiln provided in this application has the following advantages:

[0129] 1. It changes the production method of the traditional single-chamber mixing lime shaft kiln that can only use single solid fuels such as lump anthracite or coke, and can use pulverized bituminous coal and biomass powder fuels with low prices by injection, achieving efficiency improvement.

[0130] 2. It can realize the injection of industrial tail gases (such as blast furnace gas, converter gas, coke oven gas, producer gas, etc.), biomass gas and other gaseous fuels in a single-chamber shaft kiln, achieving environmental governance and carbon reduction benefits.

[0131] 3. Since a spray gun is installed in the kiln and the spray gun is arranged in a cross-section, the combustion effect is more sufficient and uniform, and the overburning rate of lime products is reduced by at least more than 10%, achieving the purpose of improving product quality and efficiency.

[0132] 4. The externally-channel-supported double-chamber lime kiln provided by this application is a double-chamber vertical kiln, which can be obtained by improving on the basis of the structure of a traditional single-chamber mixed-material lime vertical kiln, provided that there must be two lime kilns with the same kiln volume and the distance between the two kilns is appropriate.

[0133] 5. Without changing the main process structure characteristics of traditional coal-fired lime vertical kilns and gas-fired lime shaft furnaces, most lime vertical kilns can be transformed into the externally-channel-supported double-chamber lime kiln provided by this application, which is conducive to industrial promotion.

[0134] 6. Transforming a traditional single-chamber mixed-material lime vertical kiln into a double-chamber lime vertical kiln meets the requirements of environmental protection, energy conservation, etc., and avoids the fate of being phased out of traditional single-chamber mixed-material lime vertical kilns.

[0135] Example Three

[0136] By using the externally-channel-supported double-chamber lime kiln provided by this application, it is possible to realize the functional conversion and interchange between the mixed-material single-chamber countercurrent heat exchange production process and the double-chamber co-current calcination countercurrent heat storage production process. The implementation method of the pulverized coal injection and gas fuel production process will be described below.

[0137] Install a plurality of detachably arranged fuel spray guns arranged in a ring in the preheating zones of the two kiln chambers respectively, and bury them in the stone materials in the preheating zones. The two kiln chambers are alternately produced. When one kiln chamber is in calcination, the other kiln chamber is in a heat storage state. The first kiln chamber and the second kiln chamber are calcined by reversing every 15 minutes or other set times.

[0138] During production, first open the isolation valve at the intermediate interconnection part of the flue gas channels of the two kiln chambers to enable the flue gas of the two kiln chambers to communicate with each other. Then, open the valve of the external air inlet pipeline at the kiln top, and blow high-pressure combustion-supporting air into the preheating zone of the kiln chamber through the combustion-supporting air blower, so that the calcination kiln chamber is always in a positive pressure state during calcination. During the downward flow of the combustion-supporting air in the preheating zone, it exchanges heat with the hot limestone in the preheating zone for preheating. When the preheated combustion-supporting air reaches the calcination zone, it mixes with fuels such as pulverized coal or gas transported by the spray gun and then burns. The high-temperature gas after combustion and the heat-absorbed limestone flow downward together, passing through the entire calcination zone, completing the decomposition of limestone, and the limestone decomposes into calcium oxide (lime), completing the co-current calcination production process in the same direction.

[0139] When the high-temperature flue gas in the calcination zone reaches the intersection of the bottom of the calcination zone and the upper part of the cooling zone, it mixes with the cooling air from the bottom of the kiln to form a new air current. Due to the positive pressure in the kiln, the flue gas flows into the internal channels supported by multiple inclined external flue ducts here and converges in the flue gas circulation channel. The collected waste heat flue gas then flows to another kiln chamber that is storing heat. At this time, since the pressure in the heat storage kiln chamber is lower than that in the calcination chamber, the high-temperature waste gas rises from bottom to top, passes through the entire calcination zone to reach the preheating zone, contacts the limestone in the preheating zone, and conducts heat exchange to complete the countercurrent heat storage process.

[0140] When the calcination chamber is in calcination, the fuel spray gun in the heat storage chamber is closed, and the combustion air valve at the kiln top is also closed. The waste gas rises and releases waste heat to the newly charged stone materials in the upper part of the preheating zone, causing the temperature of the waste gas itself to drop to the range of 60 - 150°C and then be discharged through the waste gas pipeline at the kiln top and enter the external dust removal system of the kiln.

[0141] The calcium oxide (lime) in the cooling zones of the calcination chamber and the heat storage chamber slowly descends to the lower part of the cooling zone during the cooling process, and after cooling to the range of 50 - 150°C, it enters the ore discharge system.

[0142] The ore discharge system arranged at the bottom of the furnace is provided with multiple peripheral discharge bins and a furnace center discharge bin evenly distributed along the periphery of the kiln wall. The cooled calcium oxide (lime) then descends through the peripheral and central feeding pipes to the top of the unidirectional rotary ash discharging device, and the calcium oxide is discharged into multiple metering devices through rotation. The metered calcium oxide is discharged into the furnace bottom ash discharge bin through the discharge controller, and the material is discharged out of the furnace by a two-stage sealed discharge device.

[0143] The specific operation process of realizing the production process of injecting pulverized coal and gaseous fuel by using the externally channel-supported double-chamber lime kiln provided in this application is as follows (for the convenience of distinction, the two kiln chambers are denoted as chamber A and chamber B):

[0144] ① Open the flue duct control valve 8 to enable the waste gas in chamber A and chamber B to flow through each other;

[0145] ② Open the combustion air conversion valve 1 at the top of chamber A, and blow high-pressure combustion air into the preheating zone of the kiln chamber through the combustion air blower, so that the calcination kiln chamber is always in a positive pressure state during calcination;

[0146] ③ Open the detachable spray gun 5 to convey pulverized coal fuel or gaseous fuel into chamber A. After mixing with the high-pressure combustion air flowing from top to bottom, a hot combustion flame is formed. Since the fuel is conveyed by high-pressure air flow, the entire flame can penetrate the entire calcination zone, forming a stable high-temperature region in the calcination zone for heat exchange with the stone materials; during the heat exchange process, the flame and the stone materials move in the same direction to complete the co-current calcination process; during this process, the limestone decomposes to form carbon dioxide and calcium oxide (lime);

[0147] ④The decomposed calcium oxide slowly descends to the position of the external annular flue gas circulation channel 6, and intersects with the countercurrent cooling air flowing upward from the combustion-supporting air cap 14 at the bottom of the kiln to form a positive-pressure airflow; the airflow after intersection flows into the interior of the external annular flue gas circulation channel 6 through the internal channel of the external flue-type inclined support channel 7. A plurality of external flue-type inclined support channels 7 are provided, all of which are connected to the interior of the annular flue gas circulation channel 6;

[0148] ⑤During the same time period when the above entire operation process of Chamber A is completed, in Chamber B, the combustion-supporting air conversion valve 1 at the top of the kiln is closed, the fuel supply of the detachable spray gun 5 thereon is stopped, the waste gas conversion valve 2 at the top of the kiln is opened and connected to the external dust collector pipeline, and a negative-pressure heat storage state is formed in the entire Chamber B under the action of the dust collector induced draft fan; due to the pressure difference between Chamber A and Chamber B, the high-temperature waste heat flue gas inside the annular flue gas circulation channel 6 of Chamber A quickly flows into Chamber B, converges with the high-pressure combustion-supporting air from the combustion-supporting air cap 14 of Chamber B, forms a new positive-pressure airflow, and fully exchanges heat with the high-temperature waste gas from Chamber A and the stone materials in Chamber B from bottom to top through the entire calcination zone and preheating zone to complete countercurrent heat storage; the flue gas after heat storage is discharged out of the kiln through the waste gas conversion valve 2 at the top of the kiln and enters the dust collector;

[0149] ⑥Chamber A and Chamber B are calcined by reversing every 15 minutes or other set time, and the above operation process is repeated.

[0150] In the above operation process, the feeding of Chamber A and Chamber B is completed by the two-stage sealed feeding device 3 and the lifting and rotating composite feeding device 4; the bottom discharge of the furnace is completed by the peripheral discharging device 15, the central discharging device 16, the directional rotating ash discharging device 17, and the metering device 18; the weighed calcium oxide is discharged out of the kiln by the multi-stage sealed discharging device 19.

[0151] During the process of heat storage and calcination when Chamber A and Chamber B are mutually converted, the dust inside the external annular flue gas circulation channel 6 descends into the circulating flue ash collection bin 9, and the dust is transported to the annular cleaning pneumatic conveying pipeline 11 for dilute-phase pneumatic mixing by using the high-pressure airflow pressure naturally formed inside the kiln. The air source for pneumatic conveying comes from a separately provided external fan, and the pressure of the pneumatic conveying air is less than the airflow pressure inside the kiln. The annular cleaning pneumatic conveying pipeline 11 is provided with two external connection interfaces. Among them, the cleaning pneumatic conveying external pipeline 12 is responsible for transporting the dust material to the powder release bin 28. A cyclone dust removal and filtration device is arranged in the powder release bin 28 to separate the dust from the flue gas. The separated dust descends and falls into the lower ash hopper, and the separated flue gas rises and is connected to the powder suspension calcination channel 25 through the pressure release and regulation device 29 to participate in the suspension calcination of the powder; the cleaning pneumatic conveying internal pipeline 13 can directly transport the dust material to the lime bin inside the lower part of the kiln and be discharged out of the kiln together with the finished lime.

[0152] The stones transported by the external elevator enter the buffer bin 21 arranged at the kiln top and are screened by the fixed screening device 22 at the kiln top. The qualified stones on the screen are transported into the kiln through the internal channels of the two-stage sealed feeding device 3 and the lifting and rotating composite distributor 4; the chute-type material spreading channel 4-2 is used for material spreading to meet the process requirements of the stone material spreading during fuel injection. The undersize materials enter the undersize material collection bin 23 and fall into the external pipeline 12 of the pneumatic conveying for dust cleaning through the powder suspension calcination channel 25 and are transported to the powder release bin 28 together.

[0153] A pressure regulating and releasing valve 24 for the flue gas circulation channel is arranged in front of the flue gas control valve 8 in the external annular flue gas circulation channels 6 of the A chamber and the B chamber. When the flue gas inside the external annular flue gas circulation channels 6 of the A chamber and the B chamber needs pressure regulation, part of the waste gas can be released for pressure adjustment. The released high-temperature waste gas enters the powder suspension calcination channel 25. Due to the action of the waste gas pressure, the flue gas rises to the fixed screening device 22 and the buffer bin 21 at the kiln top and exchanges heat with the stones to achieve the purpose of drying the stones and heat exchange. The undersize powder continues to conduct suspension countercurrent heat exchange with the waste gas in the powder suspension calcination channel 25. A plurality of baffle plates 25-1 are arranged in the powder suspension calcination channel 25 to extend the heat exchange time between the flue gas and the stone powder and achieve the purpose of making full use of the waste gas heat energy.

[0154] The powder suspension calcination channel 25 has multiple functions. It can realize the dispersion and suspension of the raw stone powder in the air flow; the heat exchange between the gas and the solid phase is carried out in the whole closed rising pipeline; the waste gas can be circulated into the main waste gas pipeline at the kiln top and then discharged centrally for dust removal treatment. The whole suspension combustion process is an endothermic decomposition reaction. When the waste gas temperature rises to 550 °C, calcium carbonate begins to absorb heat and decompose into CaO, and CO 2 gas is released. As the temperature rises, the decomposition speed accelerates, and a large amount of decomposition begins above 750 °C. The decomposed CO 2 gas and part of the waste gas enter the kiln top waste gas conversion valve 2 through the waste gas branch pipe 30 or enter the main waste gas pipeline through the bypass pipeline.

[0155] Traditional double-chamber lime kilns can realize the injection of pulverized coal powder fuel and gas fuel, but they cannot use lump solid fuel for production due to process limitations. There are mainly two types of currently commonly used double-chamber vertical kilns: the bracket type structure and the hanging cylinder type structure, such as Figure 1 、 2 . Compared with the traditional double-chamber vertical kiln, the double-chamber lime kiln with external channel support provided in this application has at least the following advantages:

[0156] 1. It changes the structural mode of the furnace body calcination zone of the traditional double-chamber vertical kiln that uses in-furnace support and suspension, making the production process simpler and more practical, and solving the key problem of major production accidents that may be caused by the collapse of the in-furnace support and suspension.

[0157] 2. It changes the drawbacks of the traditional double-shaft vertical kiln in which the flue gas circulation channel is arranged inside the furnace: difficult construction and maintenance, and the channel is prone to ash accumulation and hindrance to the normal circulation of flue gas inside the channel, requiring shutdown for regular manual cleaning; the externally-channel-supported double-shaft lime kiln provided in this application sets the flue gas circulation channel outside the furnace, adopts pneumatic automatic ash cleaning and ash transportation, which is environmentally friendly and safe, without manual cleaning, and the construction and maintenance and repair are very convenient.

[0158] 3. It changes the inverted cone structure with a large upper part and a small lower part of the cooling zone of the traditional double-shaft vertical kiln. The present invention adopts a regular cone structure with a small upper part and a large lower part, and the kiln shell of the cooling zone is directly connected to the kiln shell of the calcination zone, making the kiln body more in line with the mechanical structure characteristics, not only reducing the construction difficulty and maintenance difficulty, but also making the air flow distribution inside the kiln more reasonable.

[0159] 4. It changes the drawback of the traditional fixed ash discharge device of the double-shaft kiln that it cannot rotate to discharge ash, resulting in the inability to discharge large lumps of caked materials inside the kiln and requiring manual cleaning. This application adopts a rotating ash discharge method, which can adjust the inclination of the material surface inside the kiln and automatically discharge the caked materials inside the kiln, and can also achieve discharging and weighing.

[0160] 5. Each functional structure of the externally-channel-supported double-shaft lime kiln provided in this application is compact, reasonably arranged, and convenient for operation.

[0161] 6. It changes the kiln body structure, thereby reducing the refractory usage grade inside the kiln. Not only is the selection of refractory types more extensive, but the construction is also simpler, and at the same time, the investment cost of refractory materials is also significantly reduced.

[0162] 7. The externally-channel-supported double-shaft lime kiln provided in this application can be transformed on the basis of the traditional single-shaft vertical kiln, with low construction and use investment, and continues the characteristics of high investment return rate and high investment cost performance of the traditional lime vertical kiln; compared with the investment of the traditional single-shaft mixed coal-fired lime vertical kiln, except for the increased power system, in-kiln injection combustion system and the required pulverized coal preparation system, etc., the investment of the entire production system has not increased; compared with the investment of the traditional double-shaft lime kiln, there is a large room for investment reduction under the same output.

[0163] Example 4

[0164] The externally-channel-supported double-shaft lime kiln provided in this application can also achieve suspended calcination of powdered lime.

[0165] Whether using the mixed production process provided in Example 2 or the injection of pulverized coal and gas fuel production process provided in Example 3, the production of powdered lime can be realized synchronously.

[0166] The general production process of realizing suspended calcined powdered lime is that when the stone material is lifted to the kiln top, it first enters the fixed screening device 22 at the kiln top for screening. The stone materials with a particle size of 0 - 20 mm after screening enter the compound crushing device 26 for crushing; then, by means of the powdered material suspended calcination channel 25 arranged between the two kiln bodies, part of the high-temperature waste gas flue gas in the furnace body circulation channel is released, and countercurrent suspended waste heat exchange decomposition is carried out with the fine powder stone materials with a particle size of 0 - 3 mm after crushing at the kiln top during the descending process. The heat exchange decomposition process is realized from top to bottom by a single-cylinder spinning suspension preheater, a double-cylinder spinning suspension preheater, and a constant-temperature calcination reactor.

[0167] Based on the mixing production process provided in Embodiment 2 below, the process flow of synchronously realizing suspended calcined powdered lime under the mixing production process will be described in detail:

[0168] A compound crushing device 26 is arranged at the lower part of the buffer bin 21 to crush the screened stone powder and coal particle fuel into a particle size suitable for suspended calcination;

[0169] The mixed powder of the crushed stone material and fuel enters the single-cylinder spinning suspension preheater 27 and the double-cylinder spinning suspension preheater 31 in sequence through the powdered material suspended calcination channel 25, and finally enters the interior of the constant-temperature calcination reactor 32 for decomposition and calcination;

[0170] The waste heat of the waste gas in the powdered material suspended calcination channel 25 is adjusted for the flow rate and pressure of the waste gas released into the external annular flue gas circulation channel 6 through the flue gas circulation channel pressure regulating release valves 24 respectively arranged on the two kiln chambers. An exhaust gas pipe 20 is arranged at the outlet of the flue gas circulation channel pressure regulating release valve 24, and a plurality of annularly evenly distributed flue gas nozzles 34 are arranged on the exhaust gas pipe 20 and are connected to the interior of the constant-temperature calcination reactor 32, so as to realize the dispersion, suspension, and combustion of the stone powder and fuel powder in the air flow, realize the constant-temperature flash calcination of lime powder, and decompose the lime powder into active lime.

[0171] The whole suspended combustion process is an endothermic decomposition reaction. When the waste gas temperature rises to 550 °C, calcium carbonate begins to absorb heat and decompose into CaO and release CO 2 gas. As the temperature rises, the decomposition speed accelerates, and a large amount of decomposition begins above 750 °C. When the powdered material enters the interior of the constant-temperature calcination reactor 32, it undergoes a final high-temperature flash decomposition with the high-temperature waste gas above 1000 °C from the electromagnetic induction heating temperature regulating device 33, completely releasing carbon dioxide and completing the decomposition work of the limestone powder. The waste gas of the electromagnetic induction heating temperature regulating device 33 comes from the flue gas after the powdered material release bin 28 releases the powdered material.

[0172] The decomposed CO 2Gas and some waste gases enter into the kiln top waste gas conversion valve 2 or the bypass pipeline through the waste gas branch pipe 30 and then enter into the main waste gas discharge pipeline. During the process, the heat exchange between gas and solid phases takes place inside the single-cylinder spinning suspension preheater 27 and the double-cylinder spinning suspension preheater 31, so as to realize the centralized external dust removal treatment after the waste gas flows into the main waste gas pipeline at the kiln top.

[0173] When adopting the mixing production process, the crushed fine powder stone materials and the fine powder coal fuel enter into the powder suspension calcination channel 25 synchronously. Since the ignition point of the coal fuel is lower than the waste gas temperature in the channel, direct combustion can be realized to participate in the decomposition and calcination of the stone materials. When the decomposition temperature is insufficient, the electromagnetic induction heating temperature regulating device 33 is also used to supplement the heat energy.

[0174] Based on the pulverized coal injection and gas fuel production process provided in Embodiment 3, the process flow of synchronously realizing the suspension calcination of powdered lime under the pulverized coal injection and gas fuel production process is the same as the process flow of synchronously realizing the suspension calcination of powdered lime under the mixing production process described above.

[0175] When adopting the pulverized coal injection and gas fuel production process, when the waste gas and flue gas temperature inside the powder suspension calcination channel 25 fails to reach the decomposition temperature of the fine powder stone materials, the electromagnetic induction heating temperature regulating device 33 is used to supplement the heat energy to reach the ideal decomposition and calcination temperature.

[0176] Whether it is a single-chamber mixed firing kiln, a double-chamber kiln or a rotary kiln, there are problems of narrow raw material stone usage ranges for these lime kiln types. In production practice, a large amount of small-sized limestone with a particle size less than 20 mm is sold at a low price as stone slag, resulting in great waste of mineral resources and an increase in the stone material mining cost. However, the double-chamber lime kiln with an external channel support provided in this application has a suspension combustion system, which can carry out isothermal flash calcination on fine powder stone materials (small particle powders), decompose the lime powder into active lime, and achieve the purpose of producing lime from small particle powders, realizing energy conservation and environmental protection while reducing the production cost.

[0177] The externally-channel-supported double-chamber lime kiln provided by this application uses the waste heat gas suspension method to calcine powdered lime, and can calcine limestone fines with a particle size of less than 10 mm, as well as various other raw materials of the same type. These raw materials include crushed or ground materials, powdered materials in natural or tailings, such as limestone mud cakes, etc., and the system has a wide range of adaptability. Further, this application forms a multi-stage suspension heat exchange system through a single-cylinder spinning suspension preheater 27, a double-cylinder spinning suspension preheater 31, and a constant-temperature calcination reactor 32, with high convective heat transfer efficiency, which can ensure low unit heat consumption of the system and save energy. In addition, this application cleverly utilizes the height of the lime kiln body structure and the process structure characteristics after the combination of two kilns, and performs screening and crushing at the top of the lime kiln, saving the structural and equipment costs of stone feeding, furnace body frame, platform, pipeline, etc., and effectively reducing the investment cost.

[0178] In summary, the externally-channel-supported double-chamber lime kiln provided by this application is a lime production system that transforms a coal-fired mixed-burning lime shaft kiln into a fuel-injected one. The kiln body structure is simple, compact, and practical, with high production efficiency, high output, and good economy. Especially the application of processes such as the transformation, improvement of traditional single-chamber mixed-material lime shaft kilns, and powdered material suspension calcination is of great significance for improving the overall lime production process level, reducing production costs, improving product quality, and reducing pollution and carbon emissions and improving the ecological environment.

[0179] The technical features of the above embodiments can be combined arbitrarily (as long as there is no contradiction in the combination of these technical features). For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written out should also be considered to be within the scope described in this specification.

[0180] In the above text, this application has been described in a relatively specific and detailed manner through general descriptions and specific embodiments. It should be understood that based on the technical concept of this application, several conventional adjustments or further innovations can be made to these specific embodiments; but as long as they do not deviate from the technical concept of this application, the technical solutions obtained through these conventional adjustments or further innovations also fall within the protection scope of the claims of this application.

Claims

1. An externally heated channel-supported double-shaft lime kiln for both mixing and injection, characterized in that, it includes two adjacent vertical kilns. Each vertical kiln includes a kiln body, and the kiln body has a kiln top, a kiln bottom, a kiln wall and a kiln chamber. In each kiln chamber, a preheating zone, a calcination zone and a cooling zone are formed from top to bottom; both the preheating zone and the calcination zone are straight cylindrical structures, and the cooling zone is an extended regular conical structure; on both of the two kiln tops, there are arranged a kiln top combustion-supporting air conversion valve (1), a kiln top waste gas conversion valve (2), a two-stage sealed feeding device (3) and a lifting and rotating composite feeding device (4); on both of the two kiln walls, there are arranged a plurality of detachably mounted spray guns (5) arranged in a ring. The outlet of the detachably mounted spray gun (5) is arranged at the joint of the bottom of the preheating zone and the upper part of the calcination zone; outside the kiln body at the lower part of each calcination zone, there is arranged an external annular flue gas circulation channel (6). At the tangent part between the external annular flue gas circulation channels (6) on the two kiln bodies, there is arranged a flue gas control valve (8); in each kiln chamber, there is arranged a combustion-supporting air cap (14); at the bottom of each kiln, there are arranged an ore discharging system and an ash discharging system. The ore discharging system is used to convey the cooled calcium oxide to the ash discharging system, and the ash discharging system is used to discharge the calcium oxide out of the kiln; the kiln top waste gas conversion valve (2) is connected to the external dust collector pipeline. The two-stage sealed feeding device (3) and the lifting and rotating composite feeding device (4) are used to convey the mixed stone materials and lump coal into the kiln; on the lifting and rotating composite feeding device (4), there is mounted a manipulator-type spreading device (4-1), which is used to arrange the large-particle stone materials in the center of the kiln and the small-particle stone materials around the kiln wall; on both of the two kiln tops, there are arranged kiln top external air inlet pipeline valves; on the lifting and rotating composite feeding device (4), there is also mounted a chute-type spreading channel (4-2); at the top of each kiln, there is arranged a buffer bin (21). The buffer bin (21) is used to receive the stone materials conveyed by the external elevator. Inside the buffer bin (21) at the kiln top, there are arranged a kiln top fixed screening device (22) and a preheating and drying device; the kiln top fixed screening device (22) is used to perform secondary screening on the stone materials. The lower part of the kiln top fixed screening device (22) is connected to a screen undersize collecting bin (23). The outlet of the screen undersize collecting bin (23) is connected to a compound crushing device (26). The outlet of the compound crushing device (26) is connected to a single-cylinder spinning suspension preheater (27). The outlet of the single-cylinder spinning suspension preheater (27) is connected to a powder suspension calcination channel (25). Inside the powder suspension calcination channel (25), there are arranged a number of baffle plates (25-1); the powder suspension calcination channel (25) is connected to a double-cylinder spinning suspension preheater (31). The outlet of the double-cylinder spinning suspension preheater (31) is connected to a constant-temperature calcination reaction kettle (32). The constant-temperature calcination reaction kettle (32) is connected to the waste gas outlet pipe of the powder release bin (28). The constant-temperature calcination reaction kettle (32) performs constant-temperature flash calcination on the lime powder through the high-temperature waste gas fed into it, and decomposes the lime powder into active lime; An electromagnetic induction heating temperature regulating device (33) is provided on the exhaust gas outlet pipe of the powder release bin (28). The electromagnetic induction heating temperature regulating device (33) is used to heat the exhaust gas discharged from the powder release bin (28) to a set temperature, and the exhaust gas heated to the set temperature is sent into the constant temperature calcination reactor (32); The external annular flue gas circulation channel (6) is fixed on the kiln wall through an inclined flue duct type support structure arranged below it. The inclined flue duct type support structure is an external flue duct type inclined support channel (7), and a plurality of external flue duct type inclined support channels (7) are communicated with the external annular flue gas circulation channel (6); The external annular flue gas circulation channel (6) is communicated with the powder suspension calcination channel (25) through a flue gas circulation channel pressure regulating and releasing valve (24); A circulating flue dust collecting bin (9) is arranged between two of the external flue duct type inclined support channels (7). The lower outlet of the circulating flue dust collecting bin (9) is communicated with an annular dust cleaning pneumatic conveying pipeline (11), and a pulse type ash discharging valve (10) is arranged on the pipeline for connecting the circulating flue dust collecting bin (9) and the annular dust cleaning pneumatic conveying pipeline (11).

2. The externally-channel-supported double-chamber lime kiln for both mixing and blowing according to claim 1, characterized in that, The annular dust cleaning pneumatic conveying pipeline (11) is connected to a dust cleaning pneumatic conveying external connecting pipeline (12), and the dust cleaning pneumatic conveying external connecting pipeline (12) is connected to the powder release bin (28); a cyclone dust removal and filtration device is arranged in the powder release bin (28), and the cyclone dust removal and filtration device is used to separate dust and flue gas; The separated dust descends and falls into the lower ash hopper, and the separated flue gas ascends and enters the powder suspension calcination channel (25) through a pressure release regulating device (29); The annular dust cleaning pneumatic conveying pipeline (11) is connected to a dust cleaning pneumatic conveying internal connecting pipeline (13), and the dust cleaning pneumatic conveying internal connecting pipeline (13) is used to discharge the dust material outside the kiln.

3. The externally-channel-supported double-chamber lime kiln for both mixing and blowing according to claim 1, characterized in that, The ore discharging system includes a plurality of peripheral discharging devices (15) evenly arranged circumferentially along the kiln wall, and a central discharging device (16) arranged at the center of the plurality of peripheral discharging devices (15); The ash discharging system includes a directional rotary ash discharging device (17) and a metering device (18). The feeding pipes of the peripheral discharging devices (15) and the feeding pipe of the central discharging device (16) are both communicated with the directional rotary ash discharging device (17), and the directional rotary ash discharging device (17) is used to feed calcium oxide into the plurality of metering devices (18); the metering device (18) is connected to the furnace bottom ash discharging bin, and the furnace bottom ash discharging bin is connected to a multi-stage sealed discharging device (19), and the multi-stage sealed discharging device (19) is used to discharge the metered calcium oxide out of the kiln body.

4. The externally-channel-supported double-chamber lime kiln for both mixing and blowing according to claim 1, characterized in that, From the bottom of the calcination zone to the bottom of the cooling zone, the inner diameter of the kiln chamber gradually expands; Each of the kiln bottoms is provided with an air inlet, and a kiln bottom cooling air conversion valve is arranged on the air inlet; Each kiln chamber is provided with a combustion-supporting air cap (14), and the combustion-supporting air cap (14) is located at the kiln bottom and above the ore discharge system; The structures of the two vertical kilns are symmetrical left and right.

5. A production method for producing lime by using the externally-channel-supported double-chamber lime kiln with dual functions of mixing and injection described in any one of claims 1-4, characterized in that by switching the opening and closing states of the flue gas control valve (8) arranged between the two external annular flue gas circulation channels (6), the switching between the mixing production process and the process of injecting pulverized coal and gaseous fuel is realized; wherein, closing the flue gas control valve (8) to realize the mixing production process specifically includes the following steps: S1: Close the flue gas control valve (8) so that each kiln chamber forms an independent flue gas circulation system. For any one vertical kiln, close its kiln top combustion-supporting air conversion valve (1) and open the kiln top waste gas conversion valve (2) to form a negative pressure in the kiln chamber; S2: The mixture of stone and lump coal is conveyed into the kiln by the two-stage sealed feeding device (3) and the lifting and rotating composite distributor (4); S3: When the materials in the kiln descend to the calcination zone, the combustion air from the combustion air cap (14) burns with the fuel in the stone materials, and the CO in the stone materials 2 decomposes to form calcium oxide; S4: When calcium oxide continues to descend to the lower part of the calcination zone, it exchanges heat and cools with the combustion-supporting air from the kiln bottom. The heat-exchanged combustion-supporting air continues to rise to the calcination zone to participate in combustion; after the combustion exhaust gas passes through the preheating zone and exchanges heat with the stone, the temperature of the exhaust gas drops and is discharged out of the kiln by the kiln top waste gas conversion valve (2); S5: When calcium oxide continues to descend to the lower space of the combustion-supporting air cap (14) at the kiln bottom, the entire cooling process is completed, and then it enters the ore discharge system and the ash discharge system in sequence and is discharged out of the kiln by the ash discharge system; wherein, the two vertical kilns are respectively denoted as vertical kiln A and vertical kiln B, the kiln chamber of vertical kiln A is denoted as chamber A, and the kiln chamber of vertical kiln B is denoted as chamber B; opening the flue gas control valve (8) to realize the process of injecting pulverized coal and gaseous fuel specifically includes the following steps: S1: Open the flue gas control valve (8) to enable the exhaust gases of chamber A and chamber B to communicate with each other; S2: Open the combustion-supporting air conversion valve at the kiln top of vertical kiln A and blow high-pressure combustion-supporting air into the preheating zone of chamber A to make the calcination zone in a positive pressure state; S3: Through the detachable spray gun (5), convey pulverized coal fuel or gaseous fuel into chamber A, and mix it with the high-pressure combustion-supporting air flowing from top to bottom to form a hot combustion flame. The combustion flame penetrates through the calcination zone to form a high-temperature region in the calcination zone. The stone exchanges heat in the high-temperature region of the calcination zone. During the heat exchange process, the flame and the stone move in the same direction to complete the co-current calcination process; during this process, the stone decomposes to form calcium oxide; S4: Calcium oxide slowly descends to the position of the external annular flue gas circulation channel (6), intersects with the counter-current cooling air flowing from bottom to top generated by the combustion-supporting air cap (14) at the kiln bottom, and forms a positive pressure air flow. The air flow after intersection flows into the external annular flue gas circulation channel (6); S5: During the same time period when the operations in Step S1 - S4 are completed in Chamber A, the following steps are carried out in Chamber B: close the combustion air conversion valve at the kiln top; stop the fuel supply to the detachable spray gun (5) thereon; open the connection between the waste gas conversion valve (2) at the kiln top and the external dust collector pipeline, and under the action of the external dust collector, make the whole Chamber B in a negative pressure heat storage state; due to the pressure difference between Chamber A and Chamber B, the high-temperature waste heat flue gas inside the external annular flue gas circulation channel (6) of the A vertical kiln quickly flows into Chamber B, converges with the high-pressure combustion air in Chamber B, forms a new positive pressure airflow, so that the high-temperature waste gas in Chamber A and the stone materials in Chamber B pass through the entire calcination zone and preheating zone from bottom to top for sufficient heat exchange, completing countercurrent heat storage; the flue gas after heat storage is discharged out of the kiln through the waste gas conversion valve (2) at the kiln top and enters the external dust collector. In the above operation steps, the commutation time of Chamber A and Chamber B is set artificially, and Chamber A and Chamber B carry out commutation calcination according to the set commutation time, and the above operation steps are repeated.

6. A production method for producing lime using an external-channel-supported double-chamber lime kiln with dual functions of mixing and injection as claimed in claim 5, characterized in that the suspension calcination process of powdered lime can be realized under both the mixed material production process and the process of injecting pulverized coal and gaseous fuel; the suspension calcination process of powdered lime includes: a buffer bin (21) is arranged at each kiln top, a kiln top fixed screening device (22) and a preheating and drying device are arranged inside the buffer bin (21), the kiln top fixed screening device (22) is connected to a compound crushing device (26), the outlet of the compound crushing device (26) is connected to a single-cylinder spinning suspension preheater (27), the outlet of the single-cylinder spinning suspension preheater (27) is connected to a powdered material suspension calcination channel (25), the powdered material suspension calcination channel (25) is connected to a double-cylinder spinning suspension preheater (31), the outlet of the double-cylinder spinning suspension preheater (31) is connected to a constant-temperature calcination reactor (32), the constant-temperature calcination reactor (32) is connected to the waste gas outlet pipe of a powdered material release bin (28), and an electromagnetic induction heating temperature control device (33) is arranged on the waste gas outlet pipe of the powdered material release bin (28); the screened stone powder and coal particle fuel are crushed to the target particle size for suspension calcination by the compound crushing device (26); the mixed powdered material of the crushed stone materials and fuel enters the single-cylinder spinning suspension preheater (27) and the double-cylinder spinning suspension preheater (31) in sequence through the powdered material suspension calcination channel (25), and finally enters the constant-temperature calcination reactor (32) inside, and decomposes and calcines with the waste gas from the powdered material release bin (28) to generate activated lime.

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