Closed ultrahigh-temperature fluidized calcining tank

Abstract

The invention discloses a three-dimensional circulation closed-loop type high-temperature calcination device and process, and belongs to the technical field of mineral fertilizer calcination. The device comprises a vertical sealed calcining tank, a plurality of vertical air distribution and supply pipes, a central exhaust pipe and a variable-frequency auger, the air distribution and supply pipe and the central exhaust pipe are all provided with micropores, so that a three-dimensional circulation structure with external air supply and internal air exhaust is formed, and a material layer with the height of 5 meters is uniformly heated. The process comprises the following steps: sealing and calcining at 1250 DEG C for 1 hour, blowing out the furnace and preserving heat for 1 hour, and pumping out high-temperature waste heat through a central exhaust pipe for preheating materials in another calcining tank, thereby realizing multi-furnace linkage and gradient utilization of waste heat. The device can control the calcination temperature difference within + / -20 DEG C, has the characteristics of sealing, environmental protection, uniform heating, sufficient reaction, high waste heat utilization rate and the like, and is particularly suitable for industrial high-temperature calcination production of silicon-calcium-magnesium fertilizer small-particle materials.

Description

Technical Field

[0001] This invention relates to the field of high-temperature calcination technology for mineral fertilizers, specifically to a three-dimensional circulating closed-loop high-temperature calcination device and process, which is particularly suitable for the uniform calcination, sealing and heat preservation, and waste heat preheating utilization of small granular silicon-calcium-magnesium fertilizer materials at an ultra-high temperature of 1250℃. Background Technology

[0002] Traditional silicon-calcium-magnesium fertilizer calcination equipment is mostly of an open structure or a unidirectional air supply structure, which has the following problems: 1. The deep bed material layer has a large height, resulting in uneven hot air penetration, large temperature difference, and unstable calcination quality; 2. Direct emission of high-temperature flue gas results in significant waste of waste heat and high energy consumption; 3. Without a heat preservation process, the internal reaction of the material is insufficient, which can easily lead to over-burning or under-burning; 4. Unorganized emissions of flue gas fail to meet environmental standards; 5. It is impossible to achieve multi-furnace linkage and waste heat cascade utilization.

[0003] To address the aforementioned shortcomings, this invention achieves high-temperature uniform calcination and high-efficiency energy saving through an integrated design that incorporates three-dimensional circulating air supply, central exhaust, sealed calcination, timed heat preservation, and waste heat preheating across the furnace. Summary of the Invention

[0004] 1. Technical problems to be solved 1. Achieve a temperature difference of ≤±20℃ for 5-meter-high, 50-ton-capacity silicon-calcium-magnesium fertilizer granules at 1250℃; 2. Achieve fully sealed calcination with no smoke leakage, meeting environmental protection requirements; 3. Adding a heat preservation process after calcination allows for more complete material reaction and more stable quality; 4. High-temperature waste heat can be recovered and used for preheating of the next furnace, significantly reducing energy consumption.

[0005] 2. Technical Solution Device components: - Vertical sealed calcining tank, completely airtight; - Seven vertical air distribution ducts, densely covered with micropores throughout the entire height, providing three-dimensional air supply; - A central 200mm exhaust pipe with densely packed micropores throughout its height for negative pressure exhaust; - Multiple variable frequency screw conveyors enable three-dimensional agitation of materials; - Multiple furnaces can be linked together, and waste heat can be transferred across furnaces for preheating.

[0006] Process section: - Charging → Three-dimensional circulating hot air heating → Calcination at 1250℃ for 1 hour → Sealing and heat preservation for 1 hour → Central exhaust to recover waste heat → Waste heat sent to another furnace for preheating → Sealing and cooling of this furnace for discharge → Rapid heating and calcination of the next furnace.

[0007] 3. Beneficial effects 1. Uniform temperature: Temperature difference ≤ ±20℃ at 1250℃, ensuring stable product quality; 2. Sealed and environmentally friendly: Fully enclosed structure, no dust or smoke leakage; 3. Complete reaction: Calcination for 1 hour + heat preservation for 1 hour ensures consistent reaction inside and outside the material; 4. Extreme energy saving: High-temperature waste heat is not emitted, but is used entirely for preheating the next furnace, resulting in a significant reduction in overall energy consumption; 5. Continuous production: Multiple furnaces work together, with a preheating-calcining-holding-cooling cycle, resulting in high efficiency. Attached Figure Description Figure 1 This is a schematic diagram of the structure of the three-dimensional circulating closed-loop high-temperature calcination device described in this invention. Detailed Implementation

[0008] 1. Loading Small granules of silicon-calcium-magnesium fertilizer are loaded into a vertical sealed calcining tank, with the material layer height controlled at 2.5 to 3 meters.

[0009] 2. Three-dimensional circulating heating Seven air distribution ducts supply hot air at 1200-1300℃, while the central exhaust duct simultaneously draws air, forming a three-dimensional circulation; the auger variable frequency stirring makes the material micro-fluidized and uniformly heated.

[0010] 3. Calcination at high temperature for 1 hour The temperature was stabilized at 1250℃, and the mixture was sealed and calcined for 1 hour.

[0011] 4. Shut down the furnace and maintain the temperature for 1 hour. Stop heating and air supply, maintain a completely sealed state, and keep warm for 1 hour to ensure uniform internal temperature and complete reaction of the material.

[0012] 5. Waste heat extraction and cross-furnace preheating After the heat preservation is completed, the high-temperature residual heat air is extracted through the central 200mm exhaust pipe and sent to another calcining tank to preheat the new material, raising the material temperature to 300-500℃.

[0013] 6. Cooling and discharging the material. After the waste heat is extracted, the furnace cools down naturally in a sealed state, and discharges the material in a sealed manner once the discharge temperature is reached.

[0014] 7. Next batch of rapid calcination The preheated material is rapidly heated to 1250℃ and enters a calcination-heat preservation-waste heat recovery cycle.

Claims

1. A three-dimensional circulating closed-loop high-temperature calcination device, characterized in that, The system includes a vertical sealed calcining tank; at least seven vertical air distribution and supply pipes are installed inside the sealed calcining tank, and the pipe walls are evenly distributed with a number of micro-holes for three-dimensionally spraying hot air into the material layer inside the tank; an exhaust pipe with a diameter of 200mm is installed at the center of the sealed calcining tank, and the pipe wall is also covered with micro-holes for extracting high-temperature flue gas from the central area of ​​the material layer; the hot air delivered by the air distribution and supply pipes forms a three-dimensional flow field inside the tank, and the hot air is pushed by the hot air and the negative pressure of the central exhaust pipe to form a hot air circulation; the sealed calcining tank is a completely sealed structure with no external direct exhaust flue gas outlet. After the high-temperature flue gas is extracted through the exhaust pipe, it enters the waste heat recovery or cross-furnace preheating system, forming a fully sealed closed-loop flue gas circulation system.

2. The apparatus according to claim 1, characterized in that, The opening ratio of the air distribution pipe is evenly distributed along the height of the tank, which enables three-dimensional hot air penetration of the 5-meter-high material layer and avoids local overheating or cold spots.

3. The apparatus according to claim 1, characterized in that, The air volume of the central exhaust duct is matched with the air volume of the distribution duct, so that the tank maintains a thermal balance state of slight positive or slight negative pressure, which not only prevents the leakage of waste gas, but also promotes uniform circulation of hot air.

4. The apparatus according to claim 1, characterized in that, The sealed calcining tank is equipped with at least three screw conveyors, which are driven by frequency converters with a rotation speed range of 10 to 35 rpm. These screw conveyors are used to agitate the material in three dimensions during the high-temperature calcination process, so that the material forms a microfluidic state in the hot airflow, thereby ensuring that the temperature difference is controlled within ±20℃ at the calcination temperature of 1250℃.

5. The apparatus according to claim 1, characterized in that, The sealed calcining tank can form a linkage system with another sealed calcining tank of the same structure. The high-temperature waste heat air of this furnace is transported to another furnace through the central exhaust pipe for preheating the material of the next furnace.

6. A three-dimensional circulating closed-loop high-temperature calcination process, characterized in that, Includes the following steps: 1) Load the small granular silicon-calcium-magnesium fertilizer material into a vertical sealed calcining tank, controlling the material layer height to be 2.5-3 meters; 2) Hot air at 1200-1300℃ is sprayed into the tank through seven air distribution pipes, and the hot air is made to penetrate the 5-meter material layer in three dimensions by using micropores. 3) The central exhaust duct uses negative pressure to draw out the high-temperature flue gas inside the tank, causing the surrounding hot air to converge towards the center, forming a three-dimensional circulation. 4) The auger uses a variable frequency speed to agitate the material, causing it to become microfluidized in the hot airflow and be heated evenly; 5) Heat the material to 1250℃ and calcine it in a sealed container for 1 hour; 6) After calcination, stop the temperature and furnace, and keep it in a fully sealed state for 1 hour to ensure that the internal reaction of the material is complete and the temperature is uniform; 7) After the heat preservation is completed, the high-temperature waste heat air inside the tank is extracted through the central 200mm exhaust pipe and introduced into another sealed calcining tank to preheat the next batch of silicon-calcium-magnesium fertilizer material. 8) After the waste heat is extracted from this furnace, it enters the sealing and cooling stage. After cooling is completed, the material is discharged. The next furnace is preheated and then quickly heated to the calcination temperature, realizing multi-furnace linkage and cascade utilization of waste heat.

7. The process according to claim 6, characterized in that, The calcination temperature is 1250℃, the calcination time is 1 hour, and the holding time is 1 hour. By stopping the furnace and holding the heat, the temperature difference between the inside and outside of the material is further reduced, ensuring the uniformity of calcination.

8. The process according to claim 6, characterized in that, Waste heat and hot air are extracted centrally through a central exhaust pipe and are not discharged to the outside. They are used entirely for preheating materials in another furnace, achieving full sealing, zero leakage, and high efficiency and energy saving.

9. The process according to claim 6, characterized in that, The next batch of materials, after being preheated by waste heat, can be rapidly heated from room temperature to 300-500°C, shortening the heating time and reducing fuel consumption.

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