Trona production steam calcining furnace with feeding device with mixing and preheating functions

Abstract

The invention relates to the field of trona chemical production equipment, and discloses a trona production steam calcining furnace with a mixing and preheating function feeding device, the trona production steam calcining furnace comprises a trona inlet and outlet spiral and a steam calcining furnace, the steam calcining furnace is obliquely arranged, the high end is a furnace head end, and the low end is a furnace tail end; the furnace end is connected with an alkali inlet and air outlet spiral through a furnace end seal, a discharge port of the alkali inlet and air outlet spiral extends into the furnace end of the steam calcining furnace, a feed port and an air outlet are formed above a shell of the alkali inlet and air outlet spiral, and a hollow spiral band is arranged in the alkali inlet and air outlet spiral. According to the invention, through inclined layout, sectional type material pushing plate design and heat exchange gap optimization, the problems of furnace end stockpiling, feeding spiral blockage, large material flow resistance and the like which are easy to occur when a traditional synthetic alkali calcining furnace is used for trona production are thoroughly solved, and accidents of shutdown and equipment damage caused by blockage are completely eradicated; and continuous and stable operation of large-scale production is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of natural alkali chemical production equipment, in particular to a natural alkali production steam calcining furnace with a feeding device having mixing and preheating functions. BACKGROUND

[0002] In recent years, with the rising cost of synthetic alkali raw materials and the upgrading of environmental protection requirements, natural alkali, as a low-cost and low-pollution soda ash production raw material, its development and utilization have entered a rapid development period, which promotes the transformation of the soda ash industry to natural alkali production. However, there are essential differences between the production processes of natural alkali and synthetic alkali, and the physical and chemical properties of their crystalline particles are also completely different. The natural alkali crystalline particle size is significantly larger and denser, and the amount of gas produced during calcination decomposition is much less than that of synthetic alkali. These characteristics result in significant differences in material movement state and heat transfer efficiency between natural alkali and synthetic alkali during calcination, which poses new requirements for calcination equipment.

[0003] The existing steam calcining furnaces are all designed based on the characteristics of synthetic alkali, and when directly applied to natural alkali production, they expose many insurmountable bottlenecks. On the one hand, the large particle size and high density of natural alkali lead to an increase in the pressure of the material layer, and the friction and flow resistance of the material in the furnace increase significantly, and the flow rate slows down significantly. Especially in the low-temperature area of the furnace head, the material flowability is very poor, and it is easy to form accumulation and blockage, which not only affects the smoothness of feeding, but also may cause production accidents such as equipment shutdown and component damage. On the other hand, the amount of natural alkali decomposition gas is small, and it cannot assist material flow like synthetic alkali through gas disturbance, which further aggravates the accumulation problem, and also leads to a decrease in heat transfer efficiency in the furnace, insufficient contact between the material and the heat exchange tube, incomplete calcination, unstable product quality, and high energy consumption. These problems seriously restrict the large-scale and continuous development of natural alkali production, and become a key technical obstacle that needs to be broken through during the industry transformation. It is urgent to develop a large-scale steam calcining furnace specially adapted to the characteristics of natural alkali. SUMMARY

[0004] In order to make up for the above shortcomings, the present application provides a natural alkali production steam calcining furnace with a feeding device having mixing and preheating functions, which aims to improve the problem of insufficient adaptability of the existing synthetic alkali steam calcining furnace.

[0005] To achieve the above object, the present application provides the following technical scheme: a natural soda production steam calcining furnace with a mixed and preheating function feeding device, comprising an alkali feeding and gas discharging screw and a steam calcining furnace, the steam calcining furnace is arranged obliquely, the high end is the furnace head end, and the low end is the furnace tail end; the furnace head end is connected with the alkali feeding and gas discharging screw through a furnace head seal, the discharge port of the alkali feeding and gas discharging screw extends into the furnace head of the steam calcining furnace, a feeding port and a gas outlet are arranged above the shell of the alkali feeding and gas discharging screw, and a hollow spiral belt is arranged in the alkali feeding and gas discharging screw; the steam calcining furnace comprises a calcining furnace cylinder, a pipe support plate is fixedly connected to the inner wall of the calcining furnace cylinder, steam heat exchange pipes and push plate fixing rods are supported on the pipe support plate, a gap is left between the steam heat exchange pipes and the pipe support plate, the push plate fixing rods are fixedly connected with the pipe support plate through a fixing rod fixing plate, the push plate fixing rods are arranged in concentric circles, the outer diameter of the concentric circle formed by the push plate fixing rods is smaller than the inner diameter of the concentric circle of the most inner steam heat exchange pipe group, and the number of the push plate fixing rods is less than the number of the most inner steam heat exchange pipe group; front segment spiral push plates and middle and rear segment push plates are fixedly connected to the push plate fixing rods, the front segment spiral push plates are continuous spiral belt structures, the middle and rear segment push plates are intermittent structures, and the front segment spiral push plates and the middle and rear segment push plates are fixedly connected with the push plate fixing rods through push plate fixing reinforcing plates; a front roller ring and a roller set, a rear roller ring and a roller set, and a gear ring and a transmission device are arranged outside the calcining furnace cylinder, the front roller ring and the roller set are located at the front end of the calcining furnace cylinder, the rear roller ring and the roller set are located at the rear end of the calcining furnace cylinder, the gear ring and the transmission device are located at the middle and rear parts of the calcining furnace, and the gear ring and the transmission device comprise a large gear ring connected with the calcining furnace cylinder and a small gear wheel engaged with the large gear ring, the small gear wheel is sequentially connected with a speed reducer and a variable frequency motor; a discharge cover is connected with the furnace tail end through a furnace tail seal, a discharge port is arranged at the bottom of the discharge cover, and the discharge port is connected with a variable frequency star-shaped discharge valve; a steam inlet assembly is arranged at the most tail end of the steam calcining furnace, the steam inlet assembly is connected with a steam chamber at the tail end of the calcining furnace, a steam inlet is arranged above the steam inlet assembly, and a condensed water outlet is arranged below the steam inlet assembly.

[0006] Further, the steam heat exchange pipes are arranged in several groups in concentric circles, and a gap is left between the steam heat exchange pipes in each group in the radial and axial directions, and a gap is left between the most outer steam heat exchange pipes and the inner wall of the calcining furnace cylinder.

[0007] Further, the push plate fixing rods extend from the furnace head to the rear segment of the furnace body and are fixedly connected with the pipe support plate.

[0008] Further, the front segment spiral push plates are arranged at the front segment of the furnace body and are used for enhancing the pushing force of low-temperature materials, and the middle and rear segment push plates are arranged at the rear segment of the furnace body and are suitable for the flowability of high-temperature materials.

[0009] Further, the rear roller ring and the roller set comprise a rear roller ring, two rollers and stop wheels arranged on the front and rear sides of the rear roller ring and are used for controlling the upward movement and downward movement of the steam calcining furnace during operation.

[0010] Further, the connection of the alkali feeding spiral and the furnace head end, and the connection of the discharge cover and the furnace tail end all adopt dynamic and static sealing technology.

[0011] The present application has the following beneficial effects: 1. In the present application, aiming at the core characteristics of natural alkali, such as large particle size, large density and small decomposition gas volume, through inclined layout, segmented push plate design and heat exchange gap optimization, the problems of traditional synthetic alkali calcination furnace used for natural alkali production, such as furnace head material accumulation, feeding spiral blockage and large material flow resistance, are completely solved, the stop caused by blockage and equipment damage accidents are eliminated, and continuous and stable operation of large-scale production is ensured.

[0012] 2. In the present application, a plurality of steam heat exchange pipes arranged in concentric circles are adopted, the contact area of the material and the heat exchange pipe is expanded, and the heat diffusion is more uniform through reasonable gap design between the pipes, so that the heat exchange coefficient is improved by 20% to 30% compared with the traditional equipment; the segmented push plate adapts to the flow difference of the material at different temperatures, the front segment avoids accumulation through strong pushing force, and the rear segment reasonably pushes to ensure the residence time of the material, so that the natural alkali calcination and decomposition are more sufficient, the conversion rate of soda ash is above 98.5%, the product particle size uniformity is improved by 40%, there is no local uncalcined residual material, and the product quality is greatly improved.

[0013] 3. In the present application, an expansion gap is reserved between the steam heat exchange pipe and the pipe frame plate, the damage of thermal expansion and cold shrinkage to the equipment is reduced, and the service life of the heat exchange pipe is prolonged to more than 8 years; the condensed water is recycled and utilized, combined with high-efficiency heat exchange design, the steam consumption per unit product is reduced by 10% to 15%; the variable frequency motor can flexibly adjust the rotation speed of the furnace body, adapt to different production loads, and reduce invalid energy consumption; the continuous operation time of the equipment can reach more than 8000 hours, the shutdown maintenance frequency is reduced, and the maintenance cost and production interruption loss are reduced.

[0014] 4. In the present application, mature dynamic and static sealing technology is adopted for the furnace head sealing and the furnace tail sealing, the air leakage rate is controlled to be below 0.5%, air leakage and air intrusion are effectively prevented, energy loss is avoided, and the calcination atmosphere is stabilized, and pollution emission is reduced; the variable frequency star-shaped discharge valve matched with the discharge cover has the function of locking air, further prevents air and material leakage, maintains the clean production environment, and reduces the safety risk. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A main structure schematic diagram of a natural alkali production steam calcination furnace with a feeding device having mixing and preheating functions is provided for the present application; Figure 2 A front segment spiral push plate side view of a natural alkali production steam calcination furnace with a feeding device having mixing and preheating functions is provided for the present application; Figure 3This is a side view of the middle and rear section pusher plate of a steam calcining furnace for natural alkali production with a feeding device that has both mixing and preheating functions, as proposed in this invention. Figure 4 This is a unfolded diagram of the pusher plate arrangement of a steam calcining furnace for natural alkali production with a feeding device that has both mixing and preheating functions, as proposed in this invention. Figure 5 This is a schematic diagram of the connection between the tube frame plate and the pusher plate fixing rod of a steam calcining furnace for natural alkali production with a feeding device that has both mixing and preheating functions, as proposed in this invention. Figure 6 for Figure 5 Enlarged view of point A in the middle; Figure 7 This is a schematic diagram showing the connection between the pusher plate and the fixing rod of a steam calcining furnace for natural alkali production with a feeding device that combines mixing and preheating functions, as proposed in this invention.

[0016] Legend: 1. Alkali inlet and gas outlet spiral; 101. Furnace head seal; 2. Steam calcining furnace; 201. Calcining furnace cylinder; 202. Steam heat exchange tube; 203. Tube support plate; 204. Front spiral pusher plate; 205. Front roller ring and support roller assembly; 206. Middle and rear pusher plates; 207. Pusher plate fixing rod; 20701. Fixing rod fixing plate; 20702. Pusher plate fixing reinforcement plate; 208. Gear ring and transmission device; 209. Rear roller ring and support roller chock assembly; 210. Furnace tail seal; 211. Discharge hood; 212. Steam inlet assembly. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Reference Figure 1 - Figure 7 The present invention provides an embodiment of a steam calcining furnace for natural alkali production with a feeding device that has both mixing and preheating functions. The furnace includes an alkali inlet and outlet gas screw 1 and a steam calcining furnace 2. The steam calcining furnace 2 is arranged at an incline, with the upper end being the furnace head and the lower end being the furnace tail. The furnace head is connected to the alkali inlet and outlet gas screw 1 through a furnace head seal 101. The outlet of the alkali inlet and outlet gas screw 1 extends into the furnace head of the steam calcining furnace 2. An inlet and an outlet are provided on the upper part of the shell of the alkali inlet and outlet gas screw 1. A hollow spiral band is provided inside the alkali inlet and outlet gas screw 1. The steam calcining furnace 2 includes a furnace cylinder 201. A tube rack plate 203 is fixedly connected to the inner wall of the furnace cylinder 201. Steam heat exchange tubes 202 and pusher plate fixing rods 207 are supported on the tube rack plate 203. A gap is left between the steam heat exchange tubes 202 and the tube rack plate 203. The pusher plate fixing rods 207 are welded to the tube rack plate 203 through fixing rod fixing plates 20701. The pusher plate fixing rods 207 are evenly arranged in concentric circles, and the outer diameter of the concentric circles formed by the pusher plate fixing rods 207 is smaller than the inner diameter of the concentric circles of the innermost group of steam heat exchange tubes 202. The number of pusher plate fixing rods 207 is less than the number of tubes in the innermost group of steam heat exchange tubes 202. A front spiral pusher plate 204 and a middle and rear pusher plate 206 are fixed on the pusher plate fixing rods 207. The front spiral pusher plate 204 is a continuous spiral ribbon structure, and the middle and rear pusher plates 206 are... 206 is an intermittent structure. The front spiral pusher plate 204 and the middle and rear pusher plates 206 are welded and fixed to the pusher plate fixing rod 207 via the pusher plate fixing reinforcing plate 20702. The outer side of the calcining furnace cylinder 201 is provided with a front rolling ring and support roller assembly 205, a rear rolling ring and support roller throttle assembly 209, and a gear ring and transmission device 208. The front rolling ring and support roller assembly 205 is located at the front end of the calcining furnace cylinder 201, the rear rolling ring and support roller throttle assembly 209 is located at the rear end of the calcining furnace cylinder 201, and the gear ring and transmission device 208 is located in the middle and rear part of the calcining furnace. It includes a large gear ring connected to the calcining furnace cylinder 201 and a small gear meshing with the large gear ring. The small gear is connected to a reducer and a frequency conversion motor in sequence. The tail end of the furnace is connected to a discharge hood 211 through a tail seal 210. The bottom of the discharge hood 211 is provided with a discharge port, and the discharge port is connected to a frequency conversion star discharge valve. The steam calcining furnace 2 is provided with a steam inlet assembly 212 at the very end. The steam inlet assembly 212 is connected to the steam chamber at the tail of the calcining furnace. The steam inlet assembly 212 has a steam inlet at the top and a condensate outlet at the bottom. Specifically, the external return steam calciner originally designed for natural alkali production is tailored to the core characteristics of natural alkali, such as large particle size, high density, and low decomposition gas volume. Through the coordinated operation of multiple systems, including inclined layout, segmented feeding, efficient heat exchange, and precise control, it completely solves the pain points of traditional synthetic alkali calciners used for natural alkali production, such as easy material accumulation, blockage, and high energy consumption, and achieves large-scale, long-cycle, high-efficiency, and low-consumption operation.

[0019] The equipment is arranged at an angle, with the furnace head serving as the feed and gas outlet, and the furnace tail as the discharge and steam inlet / outlet. Utilizing an optimized combination of gravity and mechanical thrust, it lays the foundation for the orderly movement of materials along the furnace axis, fundamentally reducing the risk of material accumulation. The feeding process is dominated by the alkali-inlet / gas-outlet spiral 1. After the external mixture enters through the feed inlet, its internal hollow spiral belt innovatively achieves solid-gas separation and transmission. Under the stable push of the spiral belt, the solid material smoothly enters the calcining furnace cylinder 201 without jamming or stagnation, improving feeding efficiency by 1% compared to traditional equipment. The efficiency is above 5%; at the same time, the hollow structure provides sufficient gas phase channels, and the furnace gas generated by calcination can be quickly discharged to the furnace gas treatment system through the gas outlet at the top of the alkali inlet and outlet spiral shell 1, avoiding the accumulation of furnace gas at the furnace head and the resulting pressure increase. This ensures smooth feeding and reduces the interference of furnace gas on material transportation, so that the solid-gas separation efficiency reaches more than 99%. The furnace head seal 101 adopts mature dynamic and static sealing technology, with excellent sealing performance, which can effectively prevent gas and material leakage, and the air leakage rate is controlled below 0.5%, ensuring a clean production environment and no energy loss.

[0020] Heat exchange is the core of the calcination process. Steam enters the tail chamber of the furnace through the steam inlet of the steam inlet assembly 212, and is then evenly distributed into multiple sets of concentric steam heat exchange tubes 202. The steam heat exchange tubes 202 are fixedly supported by tube rack plates 203, with a reasonable expansion gap reserved between the tube rack plates 203 and the heat exchange tubes. This ensures that the heat exchange tubes can freely expand and contract under high-temperature conditions, preventing deformation or breakage due to thermal expansion and contraction, and extending the service life of the heat exchange tubes to more than 8 years. After the material enters the calcination furnace shell 201, it naturally accumulates at the bottom of the furnace, forming a large area of ​​near-surface heat exchange with the high-temperature steam heat exchange tubes 202. The close contact allows for rapid heat absorption through efficient heat conduction, increasing the heat transfer coefficient by 20%–30% compared to traditional equipment. This results in a more complete calcination and decomposition reaction of natural alkali, achieving a soda ash conversion rate of over 98.5%. Optimized gaps are reserved radially and axially between each group of steam heat exchange tubes 202, and a reasonable distance is maintained between the outermost heat exchange tube and the inner wall of the cylinder. This ensures uniform heat diffusion and prevents material from getting stuck between the tubes. The condensate generated after heat exchange flows back along the heat exchange tubes and is discharged centrally through the condensate outlet of the steam inlet assembly 212, achieving steam recycling and reducing steam consumption per unit product by 10%–15%.

[0021] In response to the poor fluidity of natural soda ash at low temperatures and the gradual improvement in fluidity at high temperatures, the in-furnace feeding system adopts a segmented design. The feeding plate fixing rod 207 is firmly welded to the tube rack plate 203 through the fixing rod fixing plate 20701, and the outer diameter of the concentric circle formed by the fixing rod group is smaller than the inner diameter of the concentric circle of the innermost heat exchange tube group. The two maintain a reasonable radial gap, which not only avoids mutual interference during operation, but also reserves sufficient space for material flow. The front section of the furnace body is equipped with a continuous front spiral pusher plate 204. In this area, the material has just entered the furnace and is at a low temperature with extremely poor fluidity. The continuous spiral structure can generate a strong and continuous thrust, forcibly pushing the low-temperature material that is not in direct contact with the heat exchange tubes backward. This completely solves the problem of material accumulation in the low-temperature zone of the furnace head in traditional equipment and eliminates shutdown accidents caused by blockage of the feed spiral outlet. The equipment can run continuously for more than 8,000 hours. The middle and rear sections of the furnace body are equipped with intermittent middle and rear pusher plates 206. At this time, the material temperature has increased after the initial heating and the fluidity has been significantly improved. The intermittent structure can ensure the continuous advancement of the material while avoiding excessive pushing that would cause the material flow rate to be too fast. This extends the residence time of the material in the furnace by about 30%, ensuring full contact with the heat exchange tubes and uniform heating. The particle size uniformity of the soda ash product after calcination is improved by 40%, avoiding the occurrence of uncalcined residues in some areas. The pusher plate is fixed to the fixing rod by a pusher plate fixing reinforcing plate 20702, which has high connection strength and can withstand the impact of high-density materials. It is not easy to deform or be damaged.

[0022] The transmission and support system ensures stable operation of the equipment: The gear ring and transmission device 208 are located in the middle and rear of the calcining furnace. The variable frequency motor drives the reducer, which drives the small gear to mesh with the large gear ring on the outside of the cylinder. The variable frequency motor can flexibly adjust the furnace speed according to the production load to adapt to different material quantities and calcination requirements. The speed adjustment accuracy is ±0.01r / min, ensuring that the pushing strength and the material pushing speed are precisely matched. The front rolling ring and support roller group 205 supports the front end of the furnace body, and the rear rolling ring and support roller group 209 supports the rear end of the furnace body. The guide rollers on both sides of the rear rolling ring can effectively limit the upward and downward movement of the furnace body during operation, ensuring that the furnace body tilt angle is stable and the material movement trajectory is controllable, avoiding uneven material distribution or equipment vibration caused by furnace body offset.

[0023] The material discharge process achieves precise control and sealing assurance: Under the combined action of gravity and the pushing force of the pusher plate, the fully calcined material smoothly reaches the tail of the furnace and enters the discharge hood 211 through the central spiral discharge structure at the tail of the furnace. The tail seal 210 also adopts mature dynamic and static sealing technology, forming a double sealing guarantee with the furnace head seal to further prevent gas and material leakage. The discharge port at the bottom of the discharge hood 211 is connected to a variable frequency star-shaped discharge valve. This valve has both reliable air-locking function and flexible flow regulation function, which not only prevents outside air from entering and affecting the calcination atmosphere, but also avoids the leakage of high-temperature gas in the furnace and the resulting energy loss. At the same time, the discharge speed can be adjusted in real time according to the front-end production load, with an adjustment range of 30% to 120% of the design capacity, to ensure the balance of inlet and outlet, maintain the stability of the material layer in the furnace, and keep the calcination process parameters in the optimal range.

[0024] In summary, through the synergistic optimization of various systems, this external return steam calciner not only perfectly adapts to the calcination characteristics of natural alkali, but can also be applied to the processing of similar high-density, low-decomposition-gas materials such as heavy soda ash and wet ammonium chloride. Its significant advantages in preventing blockages, improving efficiency, reducing energy consumption, and stabilizing operation provide reliable equipment support for large-scale natural alkali production, greatly enhancing the economic benefits and market competitiveness of production enterprises.

[0025] Working Principle: This external return steam calciner for natural alkali production is designed specifically for the characteristics of natural alkali, such as large particle size, high density, and low decomposition gas volume. The overall arrangement is inclined, with the furnace head serving as the feed and gas outlet, and the furnace tail as the discharge and steam inlet / outlet. High-efficiency calcination is achieved through the synergistic effects of material conveying, heat exchange, segmented feeding, stable support, and precise discharge. During operation, the external mixture enters the alkali-feeding and gas-discharging spiral 1 through the feed inlet. The hollow spiral belt inside pushes the solid material to the discharge port extending into the furnace head and into the calcining furnace cylinder. 201. Simultaneously, the furnace gas generated during calcination is discharged to the furnace gas treatment system through the gas outlet at the top of the shell, achieving solid-gas separation. Steam enters the steam chamber through the steam inlet of the steam inlet assembly 212 and is then diverted to the concentrically arranged steam heat exchange tubes 202. The steam heat exchange tubes 202 are supported by the tube rack plate 203 and have reserved expansion gaps. The material contacts the high-temperature heat exchange tubes at the bottom of the furnace body and absorbs heat through heat conduction to complete calcination and decomposition. The condensate after heat exchange is discharged through the condensate outlet. The in-furnace pushing system adapts to changes in material flowability, and the pushing plate... The fixing rod 207 is welded to the tube rack plate 203 via the fixing rod fixing plate 20701, and maintains a radial clearance with the innermost heat exchange tube. The continuous front spiral pusher plate 204 at the front of the furnace provides strong thrust for low-temperature, low-flow materials, preventing the furnace head from accumulating and clogging. The intermittent middle and rear pusher plate 206 ensures that high-temperature materials are in full contact with the heat exchange tube while ensuring material propulsion. The gear ring and transmission device 208 adjust the furnace speed through a variable frequency motor to provide power for pushing the material. The front roller ring and support roller assembly 205, and the rear roller... The ring and support roller assembly 209 ensures stable operation of the furnace body. The calcined material reaches the tail of the furnace under the action of gravity and thrust, and is discharged through the discharge hood 211 and the bottom discharge port. The variable frequency star discharge valve connected to the discharge port has both air-locking and flow regulation functions to prevent gas and material leakage and adapt to production load. The furnace head seal 101 and the furnace tail seal 210 adopt mature dynamic and static sealing technology to ensure the connection sealing performance. The whole system adapts to the calcination requirements of natural alkali and similar materials through multi-system collaboration, realizing long-cycle and high-efficiency operation under large-scale production.

[0026] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A steam calcining furnace for natural alkali production with a feeding device that combines mixing and preheating functions, characterized in that, It includes an alkali inlet and gas outlet spiral (1) and a steam calciner (2). The steam calciner (2) is arranged at an angle, with the upper end being the furnace head and the lower end being the furnace tail. The furnace head end is connected to the alkali inlet and outlet spiral (1) through the furnace head seal (101). The outlet of the alkali inlet and outlet spiral (1) extends into the furnace head of the steam calcining furnace (2). The shell of the alkali inlet and outlet spiral (1) is provided with an inlet and an outlet. A hollow spiral strip is provided inside the alkali inlet and outlet spiral (1). The steam calcining furnace (2) includes a furnace cylinder (201). A tube rack plate (203) is fixedly connected to the inner wall of the furnace cylinder (201). A steam heat exchange tube (202) and a pusher plate fixing rod (207) are supported on the tube rack plate (203). There is a gap between the steam heat exchange tube (202) and the tube rack plate (203). The pusher plate fixing rod (207) is welded to the tube rack plate (203) through a fixing rod fixing plate (20701). The pusher plate fixing rods (207) are arranged in concentric circles. The outer diameter of the concentric circle formed by the pusher plate fixing rods (207) is smaller than the inner diameter of the concentric circle of the innermost steam heat exchange tube (202) group. The number of pusher plate fixing rods (207) is less than the number of tubes in the innermost steam heat exchange tube (202) group. The pusher plate fixing rod (207) is fixed with a front spiral pusher plate (204) and a middle and rear pusher plate (206). The front spiral pusher plate (204) is a continuous spiral strip structure, and the middle and rear pusher plate (206) is an intermittent structure. The front spiral pusher plate (204) and the middle and rear pusher plate (206) are welded and fixed to the pusher plate fixing rod (207) through a pusher plate fixing reinforcing plate (20702). The outer side of the calcining furnace cylinder (201) is provided with a front rolling ring and support roller assembly (205), a rear rolling ring and support roller chock assembly (209), and a gear ring and transmission device (208). The front rolling ring and support roller assembly (205) is located at the front end of the calcining furnace cylinder (201), the rear rolling ring and support roller chock assembly (209) is located at the rear end of the calcining furnace cylinder (201), and the gear ring and transmission device (208) is located in the middle and rear part of the calcining furnace. It includes a large gear ring connected to the calcining furnace cylinder (201) and a small gear meshing with the large gear ring. The small gear is connected in sequence to a reducer and a variable frequency motor. The tail end of the furnace is connected to a discharge hood (211) through a tail seal (210). The bottom of the discharge hood (211) is provided with a discharge port, and the discharge port is connected to a variable frequency star discharge valve. The steam calcining furnace (2) is provided with a steam inlet assembly (212) at the very end. The steam inlet assembly (212) is connected to the steam chamber at the tail of the calcining furnace. A steam inlet is provided above the steam inlet assembly (212) and a condensate outlet is provided below it.

2. The steam calcining furnace for natural alkali production with a mixing and preheating feeding device according to claim 1, characterized in that: The steam heat exchange tubes (202) are arranged in several groups in concentric circles. There are gaps between each group of steam heat exchange tubes (202) in the radial and axial directions. The outermost steam heat exchange tubes (202) have gaps with the inner wall of the calcining furnace cylinder (201).

3. A steam calcining furnace for natural alkali production with a mixing and preheating feeding device according to claim 1, characterized in that: The pusher plate fixing rod (207) extends from the furnace head to the rear section of the furnace body and is fixedly connected to the tube rack plate (203).

4. A steam calcining furnace for natural alkali production with a feeding device that combines mixing and preheating functions, as described in claim 1, is characterized in that: The front spiral pusher plate (204) is located at the front of the furnace body to enhance the pushing force of low-temperature materials; the middle and rear pusher plate (206) is located at the rear of the furnace body to adapt to the flowability of high-temperature materials.

5. A steam calcining furnace for natural alkali production with a feeding device that combines mixing and preheating functions, as described in claim 1, is characterized in that: The rear rolling ring and support roller assembly (209) includes a rear rolling ring, two support rollers, and spur rollers located on the front and rear sides of the rear rolling ring, used to control the upward and downward movement of the steam calcining furnace (2) during operation.

6. A steam calcining furnace for natural alkali production with a feeding device that combines mixing and preheating functions, as described in claim 1, is characterized in that: The connection between the alkali inlet and outlet gas spiral (1) and the furnace head end, and the connection between the discharge hood (211) and the furnace tail end, both adopt dynamic and static sealing technology.

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