A jet feeding device for a flash calcination furnace of light burned magnesium oxide

Abstract

The present invention discloses a jet feeding device for a flash calcination furnace of light-burned magnesia, which includes a receiving chamber. One end of the receiving chamber is connected to the outer wall of an intake pipe through a flange, and a nozzle is installed on the intake pipe. The outer wall of the receiving chamber is provided with a feed pipe. The other end of the receiving chamber is connected to the large-diameter port of a contraction pipe through a flange. The small-diameter port of the contraction pipe is integrally formed with one end of a throat pipe, and the other end of the throat pipe is connected to an expansion pipe through a flange. In this device, high-temperature flue gas is used as the primary fluid, and material particles are used as the entrainment medium. The high-temperature flue gas ejected from the nozzle forms a high-speed airflow that has an entrainment effect on the fluid in the receiving chamber. At the same time, according to Bernoulli's principle, a negative pressure zone is formed in the receiving chamber, making the internal pressure of the receiving chamber less than the pressure at the material particle inlet. Under the dual action of the entrainment of the high-speed gas and the pressure difference, the material particles are violently mixed in the contraction section, and frequent momentum and energy exchanges occur.

Description

Technical Field

[0001] The present invention relates to the technical field of calcining furnaces, and specifically to a jet feeding device for a flash calcining furnace of light-burned magnesia. Background Art

[0002] The flash calcination technology has been applied to magnesite calcination for about six or seven years, shortening the magnesite calcination time from the hour level to the second level reaction, and reducing the energy consumption per ton of product by about 20 - 30%. However, so far, the design of flash calcination furnaces has all been completed relying on production experience, lacking systematic design theory and calculation support. Currently, the calcination raw material of the flash furnace is particulate matter with a particle size of 70 μm, and its feeding is all set with a single feeding port on the side of the main calcining furnace body, resulting in feeding segregation, uneven mixing of high-temperature flue gas and raw material powder, and further leading to drawbacks such as material dropping in the calcining furnace and unstable calcination quality.

[0003] The high-temperature flue gas and the material particles do not contact and mix sufficiently, and the uneven distribution of the material particles due to the unreasonable structure at the feeding part leads to the phenomenon of material dropping in the calcining furnace. Due to the above-mentioned defects existing in the feeding of the existing flash calcination furnace, the heat transfer efficiency between the high-temperature flue gas and the material particles in the calcining furnace has not reached the best, the calcination quality is unstable, and the product recovery rate of the calcining furnace is low. Summary of the Invention

[0004] The purpose of the present invention is to provide a jet feeding device for a flash calcining furnace of light-burned magnesia, so that the material particles entering the calcining furnace can be quickly and evenly mixed with the high-temperature flue gas, improve the heat transfer efficiency of the gas-solid two-phase in the flash furnace, reduce the calcination energy consumption, and improve the product quality.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A jet feeding device for a flash calcining furnace of light-burned magnesia, including a receiving chamber, one end of the receiving chamber is connected to the outer side wall of an inlet pipe through a flange, and a nozzle is installed on the inlet pipe. The outer side wall of the receiving chamber is installed with a feeding pipe. The other end of the receiving chamber is connected to the large-diameter port of a contraction pipe through a flange. The small-diameter port of the contraction pipe is integrally formed with one end of a throat pipe, and the other end of the throat pipe is connected to an expansion pipe through a flange;

[0006] The expansion pipe is connected to the flash calcining furnace through a discharge port.

[0007] Compared with the prior art, the beneficial effects of the present invention are:

[0008] By proposing a jet feeding device for a light-burned magnesia flash calciner, which uses high-temperature flue gas as the primary fluid and material particles as the entrainment medium. The high-temperature flue gas is ejected from the nozzle to form a high-speed airflow that entrains the fluid in the receiving chamber. At the same time, according to Bernoulli's principle, a negative pressure zone is formed in the receiving chamber, making the internal pressure of the receiving chamber less than the pressure at the material particle inlet. Under the dual action of the entrainment of the high-speed gas and the pressure difference, the material particles are violently mixed in the contraction section, and frequent momentum and energy exchanges occur. After the two-phase flow enters the throat and gradually stabilizes, it enters the expansion section, where the velocity gradually decreases and the pressure gradually increases. The two-phase flow is ejected from the discharge port at a certain velocity and pressure and enters the calciner. Moreover, the feeding device described in the present invention can be fed through 1 to 4 feeding pipes according to the feeding requirements, and multiple feeding ports are used, and the mixing effect is better under the same conditions. Compared with the traditional feeding method, the jet feeding device proposed in the present invention can use one or more feeding ports for feeding, realizing the rapid and full mixing of material particles and high-temperature flue gas, solving the problem of mixing segregation of material particles and high-temperature flue gas, eliminating the material dropping phenomenon during feeding, improving the heat and mass transfer between the material in the furnace and the high-temperature flue gas, and improving the product quality and product recovery rate of the calciner. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic structural diagram of the jet feeding device of the present invention.

[0010] Figure 2 It is a schematic sectional view of the jet feeding device of the present invention.

[0011] Figure 3 It is a schematic sectional view of the nozzle of the present invention.

[0012] Figure 4 It is a schematic installation diagram of the jet feeding device of the present invention.

[0013] Figure 5 It is a schematic diagram of the feeding pipe layout of the present invention.

[0014] Figure 6 It is a schematic diagram of the feeding pipe layout of the second embodiment of the present invention.

[0015] Figure 7 It is a schematic diagram of the feeding pipe layout of the third embodiment of the present invention.

[0016] Figure 8 It is a schematic diagram of the feeding pipe layout of the fourth embodiment of the present invention.

[0017] Figure 9 It is a schematic diagram of the mixing index of the comparative example, Example 1, Example 2 and Example 3.

[0018] 1. Inlet pipe; 2. Receiving chamber; 3. Feed pipe; 4. Converging pipe; 5. Throat pipe; 6. Diverging pipe; 7. Discharge port; 8. Flash calciner; 9. First insulation layer; 10. Second insulation layer; 11. Third insulation layer; 12. Nozzle. Detailed implementation manner

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Please refer to Figures 1-5 , the present invention provides a technical solution: a jet feeding device for a light-burned magnesia flash calciner, including a receiving chamber 2. One end of the receiving chamber 2 is connected to the outer side wall of the inlet pipe 1 through a flange, and a nozzle 12 is installed on the inlet pipe 1, so that the nozzle 12 is placed in the inner cavity of the receiving chamber 2. The outer side wall of the receiving chamber 2 is provided with a feed pipe 3, and the feed pipe 3 forms a certain angle with the axis of the receiving chamber 2. The other end of the receiving chamber 2 is connected to the large-diameter port of a converging pipe 4 through a flange. The small-diameter port of the converging pipe 4 is integrally formed with one end of a throat pipe 5, and the other end of the throat pipe 5 is connected to a diverging pipe 6 through a flange;

[0021] The air inlet of the inlet pipe 1 is connected to a vertical hot blast stove; the input end of the feed pipe 3 is connected to a screw feeder; the diverging pipe 6 is connected to a flash calciner 8 through a discharge port 7.

[0022] The first insulation layer 9, the second insulation layer 10 and the third insulation layer 11 are provided in the inlet pipe 1, the receiving chamber 2, the feed pipe 3, the converging pipe 4, the throat pipe 5 and the diverging pipe 6, which not only ensures the temperature resistance of the device but also reduces the heat loss. The thicknesses of the first insulation layer 9, the second insulation layer 10 and the third insulation layer 11 increase layer by layer. The first insulation layer 9 is made of aluminosilicate cotton fiber, the second insulation layer 10 is made of lightweight fireclay bricks, and the third insulation layer 11 is made of heavyweight fireclay bricks. Since the third insulation layer 11 is in direct contact with the material, it has a certain wear resistance.

[0023] The inlet diameter of the nozzle 12 is 3 to 6 times the outlet diameter; the distance between the inlet cross-section and the outlet cross-section of the nozzle 12 is 10 times the outlet diameter of the nozzle 12.

[0024] The diameter of the receiving chamber 2 is 16 times the outlet diameter of the nozzle 12; the length of the receiving chamber 2 is 3.5 times the outlet diameter of the nozzle 12; the diameter of the throat 5 is 10 times the outlet diameter of the nozzle 12; the length of the throat 5 is 2 to 10 times the diameter of the throat 5; the length of the diverging tube 6 is 2 to 3 times the diameter of the throat 5; the diameter of the feed pipe 3 is 1 to 6 times the outlet diameter of the nozzle 12.

[0025] The divergence angle of the diverging tube 6 is 10 to 30 degrees; the angle between the forming line of the converging tube 4 and the axis is 30 degrees.

[0026] Working principle: The intake pipe 1 is connected to a vertical hot blast stove to provide heat for the flash calciner 8, the feed pipe 3 is connected to a screw feeder, and the discharge port 7 is connected to the flash calciner 8 to send a mixture of material particles and high-temperature flue gas into the calciner.

[0027] During operation, high-temperature flue gas under a certain pressure is ejected from the flue gas nozzle 12 at high speed. According to Bernoulli's principle, the high-speed jet entrains the surrounding gas during its forward movement, forming a negative pressure zone in the receiving chamber 2. The material particles enter the receiving chamber 2 under the action of negative pressure and jet entrainment and are violently mixed with the high-temperature flue gas in the throat 5, and then are discharged from the diverging tube 7 and enter the calciner.

[0028] Please refer to Figure 6 , the present invention provides another technical solution. Different from the above technical solution, there are 2 feed pipes 3, and the feed pipes 3 are symmetrically arranged on the outer side wall of the receiving chamber 2. The other technical features remain unchanged.

[0029] Please refer to Figure 7 , the present invention provides a third technical solution. Different from the first technical solution described above, there are 3 feed pipes 3, and the 3 feed pipes 3 are circumferentially arranged on the outer side wall of the receiving chamber 2. The other technical features remain unchanged.

[0030] Please refer to Figure 8 , the present invention provides a fourth technical solution. Different from the first technical solution described above, there are 4 feed pipes 3, and the 4 feed pipes 3 are circumferentially arranged on the outer side wall of the receiving chamber 2. The other technical features remain unchanged.

[0031] This application adopts multi-pipe feeding, jet action and Bernoulli's principle to achieve high-speed mixing of the feed of the light-burned magnesia flash calciner, solve the problem of feed segregation, eliminate the falling material phenomenon of the flash furnace feed on the one hand, and improve the problem of unstable calcination quality on the other hand. The jet-type feeding device described in the present invention can strengthen the heat and mass transfer between the material particles and the high-temperature flue gas, improve the heat utilization rate, improve the product quality, and increase the product recovery rate.

[0032] Embodiment

[0033] Comparison of the parameters of the original structure and the existing structure

[0034]

[0035] Please refer to Figure 9 , when the jet feeding device is adopted, its mixing index is greater than that when the original device is adopted. Moreover, when the jet feeding method is adopted in the design method, the mixing effect of the materials is enhanced, the dispersion of the materials in the furnace is better, which is conducive to the heat transfer and mass transfer between the flue gas and the materials, and has advantages in improving the thermal intensity of the furnace.

[0036] In addition, when pursuing the best material mixing effect, the uniform distribution of the materials in the furnace is further improved, the feeding segregation is improved, and the occurrence of situations such as uneven mixing of the raw material powder leading to material dropping is avoided.

Claims

1. A jet feeding device for a light-burned magnesia flash calciner, characterized in that: It includes a receiving chamber (2), one end of the receiving chamber (2) is connected to the outer wall of the intake pipe (1) through a flange, and a nozzle (12) is installed on the intake pipe (1). The inlet diameter of the nozzle (12) is 3 to 6 times the outlet diameter. The diameter of the receiving chamber (2) is 16 times the outlet diameter of the nozzle (12). A feed pipe (3) is installed on the outer wall of the receiving chamber (2). The other end of the receiving chamber (2) is connected to the large-diameter port of a contraction pipe (4) through a flange. One end of a throat pipe (5) is integrally formed at the small-diameter port of the contraction pipe (4). The other end of the throat pipe (5) is connected to a diffuser pipe (6) through a flange; The diffuser pipe (6) is connected to a flash calciner (8) through a discharge port (7).

2. The jet feeding device of the light-burned magnesia flash calcination furnace according to claim 1, characterized in that: The intake pipe (1), the receiving chamber (2), the feed pipe (3), the contraction pipe (4), the throat pipe (5), and the diffuser pipe (6) are all provided with a first heat-insulating layer (9), a second heat-insulating layer (10), and a third heat-insulating layer (11), and the thicknesses of the first heat-insulating layer (9), the second heat-insulating layer (10), and the third heat-insulating layer (11) increase layer by layer.

3. The jet feeding device of the light-burned magnesia flash calcination furnace according to claim 1, characterized in that: The inlet diameter of the nozzle (12) is 3 to 6 times the outlet diameter; the distance between the inlet cross-section and the outlet cross-section of the nozzle (12) is 10 times the outlet diameter of the nozzle (12).

4. The jet feeding device of the light-burned magnesia flash calciner according to claim 1, characterized in that: The diameter of the receiving chamber (2) is 16 times the outlet diameter of the nozzle (12); the length of the receiving chamber (2) is 3.5 times the outlet diameter of the nozzle (12); the diameter of the throat pipe (5) is 10 times the outlet diameter of the nozzle (12); the length of the throat pipe (5) is 2 to 10 times the diameter of the throat pipe (5); the length of the diffuser pipe (6) is 2 to 3 times the diameter of the throat pipe (5); the diameter of the feed pipe (3) is 1 to 6 times the outlet diameter of the nozzle (12).

5. The jet feeding device of the light-burned magnesia flash calcination furnace according to claim 1, characterized in that: The divergence angle of the diffuser pipe (6) is 10 to 30 degrees; The angle between the forming line of the contraction pipe (4) and the axis is 30 degrees.

6. The jet feeding device of the light-burned magnesia flash calcination furnace according to claim 1, wherein: There is 1 feed pipe (3); or there are 2 feed pipes (3), and the feed pipes (3) are symmetrically arranged on the outer wall of the receiving chamber (2); or there are 3 feed pipes (3), and the 3 feed pipes (3) are circumferentially arranged on the outer wall of the receiving chamber (2); or there are 4 feed pipes (3), and the 4 feed pipes (3) are circumferentially arranged on the outer wall of the receiving chamber (2).

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