Clay suspension calcination decomposing furnace

Abstract

The invention relates to the technical field of industrial production calcination, in particular to a clay suspension calcination decomposing furnace which comprises a decomposing furnace body, an external hanging furnace is arranged outside the decomposing furnace body, and the decomposing furnace body comprises a cone mixing chamber, a main combustion chamber, a top vortex mixing chamber and a connecting air pipe which are sequentially communicated with one another. The bottom of the conical mixing chamber is connected with a C1-stage air outlet of the preheater, and the side part of the conical mixing chamber is tangentially communicated with an air outlet pipe of the external furnace; a plurality of material scattering boxes are arranged on the main combustion chamber, and the top vortex mixing chamber is connected with a cyclone cylinder at the lowest stage of the preheater through a connecting air pipe. The temperature of high-temperature flue gas can be adjusted, crusting and material inactivation caused by too high flue gas temperature are prevented, sufficient mixing of the flue gas, materials and fuel is improved, and the decomposing furnace can be controlled to be in a reducing atmosphere.

Description

Technical Field

[0001] This invention relates to the field of industrial calcination technology, specifically a clay suspension calcination decomposition furnace. Background Technology

[0002] In cement production, clay calcination technology is increasingly being promoted and applied because it does not produce carbon dioxide during calcination, only fuel gas. Compared to ordinary cement clinker, it reduces carbon dioxide emissions. The suitable calcination temperature for clay is 650-850℃; temperatures above 950℃ will cause it to lose its activity. If clay is calcined in a reducing atmosphere (where iron in the clay forms Fe3O4), the finished product is grayish-black, and this does not affect the color of the cement when mixed with clinker and ground into cement. However, if clay is calcined in an oxidizing atmosphere (where Fe2O3 is formed), the finished product is generally reddish-brown, and this will affect the color of the cement when mixed with clinker and ground into cement.

[0003] Since clay suspension calcination does not have a rotary kiln to provide high-temperature flue gas, in order to ensure that the fuel in the decomposition furnace can burn quickly, existing clay suspension calcination decomposition furnaces often need to be connected to an external hot blast stove or external furnace to provide initial heat. However, since the hot blast stove or external furnace uses air (with an oxygen content of 21%) as the primary air, the high-temperature flue gas generated by the hot blast stove or external furnace has a relatively high oxygen content and temperature, which cannot meet the calcination requirements of the suspension clay decomposition furnace.

[0004] Therefore, it is necessary to design a calcination furnace to control the oxygen content and temperature of the initial hot air entering the decomposition furnace, so as to ensure that the clay is calcined in a reducing atmosphere in the decomposition furnace and does not lose its activity due to over-burning at high temperature. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a clay suspension calcination decomposition furnace, which, by controlling the temperature of the hot air inlet and the oxygen content, ensures that the clay is calcined in a reducing atmosphere within the furnace. After calcination, the clay is gray in color and does not lose its activity due to overheating.

[0006] The technical solution adopted by this invention to solve its technical problem is: A clay suspension calcination decomposition furnace includes a decomposition furnace with an external furnace. The decomposition furnace includes a conical mixing chamber, a main combustion chamber, a top vortex mixing chamber, and connecting air ducts that are sequentially connected to each other. The bottom of the conical mixing chamber is connected to the C1 stage air outlet of the preheater, and the side of the conical mixing chamber is tangentially connected to the air outlet duct of the external furnace. Several material feeding boxes are provided on the main combustion chamber, and the top vortex mixing chamber is connected to the lowest stage cyclone of the preheater through the connecting air duct.

[0007] Compared with the prior art, the beneficial effects of the present invention are: This invention mixes the flue gas from the preheater C1 outlet with the high-temperature flue gas from the external furnace, which can regulate the temperature of the high-temperature flue gas and prevent crusting and loss of material activity due to excessively high flue gas temperature. Furthermore, by increasing the fuel consumption of the external furnace, the oxygen content in the high-temperature flue gas can be reduced, making it easier to control the reducing atmosphere inside the decomposition furnace. By setting up multiple feeding boxes for graded feeding, it is possible to prevent excessively high temperatures in local areas inside the decomposition furnace, which could lead to over-burning and crusting of materials. The top and bottom of the decomposition furnace adopt swirling structures, which facilitates full contact and mixing of flue gas, materials, and fuel.

[0008] As a preferred embodiment, a further technical solution of the present invention is: Preferably, a circulating air inlet pipe is provided at the bottom of the cone-shaped mixing chamber. The circulating air inlet pipe includes a vertical pipe and a side pipe. The bottom of the vertical pipe is connected to the exhaust assembly, and the side pipe is connected to the C1 stage air outlet of the preheater.

[0009] Preferably, the outflow assembly includes an electric slide gate valve and a flap valve, with the electric slide gate valve positioned above the flap valve.

[0010] Preferably, the main combustion chamber includes a cylinder, and a number of material distribution boxes are arranged from top to bottom on the lower part of the cylinder. A burner is arranged on the cylinder near some of the material distribution boxes.

[0011] Preferably, the swirling direction of the high-temperature flue gas is opposite to the swirling direction of the top vortex mixing chamber. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the decomposition furnace in this invention; Figure 2 yes Figure 1 AA section view; Figure 3 This is a top view of the present invention; Figure 4 yes Figure 1 BB section view; Figure 5 This is a flowchart illustrating the present invention; Explanation of reference numerals in the attached drawings: 1. Conical mixing chamber; 2. Main combustion chamber; 3. Top vortex mixing chamber; 4. Connecting air duct; 5. External boiler; 6. High-temperature flue gas inlet duct; 7. Exit duct; 8. Circulating air inlet duct; 801. Vertical duct; 802. Lateral duct; 9. Electric slide gate valve; 10. Flip valve; 11. Feeding box; 12. Burner; 13. Exhaust fan; 14. Preheater C1 stage; 15. Cyclone. Detailed Implementation

[0013] The present invention will be further illustrated below with reference to specific embodiments. The purpose of this illustration is solely to provide a better understanding of the invention. Therefore, the examples given do not limit the scope of protection of the present invention.

[0014] like Figures 1 to 5 As shown, a clay suspension calcination decomposition furnace is provided. The decomposition furnace mainly consists of a conical mixing chamber 1, a main combustion chamber 2, a top vortex mixing chamber 3, and a connecting air duct 4. The conical mixing chamber 1 is located at the bottom of the main combustion chamber 2, and the outlet of the conical mixing chamber 1 is connected to the inlet of the main combustion chamber 2. The top vortex mixing chamber 3 is located at the top of the main combustion chamber 2, and the inlet of the top vortex mixing chamber 3 is connected to the outlet of the main combustion chamber 2. The connecting air duct 4 is located on one side of the main combustion chamber 2, and the inlet of the connecting air duct 4 is connected to the outlet of the top vortex mixing chamber 3. The outlet of the connecting air duct 4 is connected to the cyclone 15 at the bottom of the preheater.

[0015] An external furnace 5 (hot blast furnace) is installed outside the decomposition furnace. A high-temperature flue gas inlet pipe 6 is installed on the side of the conical mixing chamber 1. The high-temperature flue gas inlet pipe 6 is connected to the outlet pipe 7 at the bottom of the external furnace 5. The high-temperature flue gas (temperature 900℃-1000℃, oxygen content 12%-15%) generated by the external furnace 5 enters the conical mixing chamber 1 tangentially along the outlet pipe 7 and the high-temperature flue gas inlet pipe 6, forming a vortex airflow.

[0016] A circulating air inlet pipe 8 is provided at the bottom of the conical mixing chamber 1. The circulating air inlet pipe 8 consists of a vertical pipe 801 and a side pipe 802, which are in a semi-H-shaped structure. The side pipe 802 is located in the lower middle part of the vertical pipe 801 and its upper end is connected to the vertical pipe 801. The lower end of the side pipe 802 is connected to the outlet of the preheater C1 stage 14 through the induced draft fan 13. Part of the circulating air of the preheater C1 stage 14 (the circulating air is the exhaust gas of the preheater C1 stage, with a wind temperature of about 300°C and an oxygen content of about 2%) enters the vertical pipe through the side pipe 802 at the bottom of the decomposition furnace and enters the conical mixing chamber 1 along the vertical pipe at a higher wind speed.

[0017] An external drainage assembly is installed at the bottom of the vertical pipe. The external drainage assembly consists of an electric slide gate valve 9 and a flap valve 10, with the electric slide gate valve 9 positioned above the flap valve 10 during installation. The electric slide gate valve 9 and the flap valve 10 open periodically to drain the scale that falls from above, preventing the scale from clogging the pipe.

[0018] The main combustion chamber 2 has a cylindrical structure with several material distribution boxes 11 located at the bottom. These boxes are positioned at different heights from top to bottom and are used to disperse the addition of raw clay. Burners 12 are installed near some of the material distribution boxes 11 to inject fuel. The injected fuel, flue gas, and raw clay are thoroughly mixed to prevent high internal temperatures. This embodiment can also ensure a negative oxygen state at the decomposition furnace outlet by adjusting the primary air flow of the burners 12 and the oxygen content of the high-temperature flue gas from the hot blast stove.

[0019] In this embodiment, a swirling channel is provided inside the top vortex mixing chamber 3. The inlet of the swirling channel is connected to the outlet of the main combustion chamber 2, and the outlet of the swirling channel is connected to the inlet of the connecting duct 4. The swirling direction of the vortex airflow formed by the high-temperature flue gas entering the cone mixing chamber 1 is opposite to the swirling direction of the swirling channel inside the top vortex mixing chamber 3.

[0020] The specific working principle of this embodiment is as follows: S1. Circulating air from the outlet of preheater C1 stage 14 enters through the side pipe 802 at the bottom of the decomposition furnace and enters the cone mixing chamber 1 of the decomposition furnace vertically upward along the vertical pipe at a higher wind speed. The electric slide valve 9 and flap valve 10 at the bottom of the vertical pipe are opened at regular intervals to discharge the fallen scale and prevent the scale from blocking the side pipe 802.

[0021] S2. High-temperature flue gas from the external furnace 5 (or hot blast stove) enters tangentially from the side of the cone mixing chamber 1, forming a vortex airflow. The circulating air entering from the bottom carries up the falling raw clay and mixes with the high-temperature flue gas, entering the main combustion chamber 2 upwards.

[0022] S3. In the lower part of the main combustion chamber 2, raw clay is dispersed and filled through the feeding boxes 11 at different heights. Then, fuel is injected through the burner 12 to fully mix the raw clay with the flue gas and fuel. As the material and fuel are mixed and rise with the flue gas, the fuel continues to burn and release heat and consume oxygen. The material further absorbs heat and decomposes, and finally enters the top vortex mixing chamber 3.

[0023] S4. Since the swirling direction in the top vortex mixing chamber 3 is opposite to the swirling direction formed in the cone mixing chamber 1, when the material, unburned fuel and flue gas enter the top vortex mixing chamber 3, the swirling direction changes, which promotes efficient mixing and contact of the material, unburned fuel and flue gas, promotes full contact between the remaining oxygen and fuel, consumes the excess oxygen, improves the fuel combustion rate, and ensures that the outlet of the top vortex mixing chamber 3 is in a negative oxygen state.

[0024] S5. Connecting duct 4 connects the top vortex mixing chamber 3 to the lowest cyclone of the preheater. The oxygen in connecting duct 4 has been exhausted, and the flue gas is in a reducing atmosphere. The calcined clay turns grayish-black. Finally, the high-temperature flue gas carries the decomposed clay into the lowest cyclone 15 of the preheater. The calcined clay material is collected and cooled, and the flue gas goes up to preheat the raw clay.

[0025] This invention mixes the circulating air from the C1 stage outlet of the preheater with the high-temperature flue gas from the hot blast stove. This regulates the temperature of the high-temperature flue gas, preventing crusting and material deactivation caused by excessively high temperatures. It also increases the fuel consumption of the external furnace and reduces oxygen intake, helping to control the reducing atmosphere in the decomposition furnace. Staged combustion and staged feeding in the main combustion chamber effectively prevent localized high temperatures in the decomposition furnace, avoiding overburning and crusting. A semi-H-shaped circulating air inlet pipe is added to the bottom of the decomposition furnace to periodically remove crusting, preventing blockage of side pipes and ensuring stable system operation.

[0026] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. All equivalent changes made based on the description and drawings of the present invention are included within the scope of the present invention.

Claims

1. A clay suspension calcination decomposition furnace, comprising a decomposition furnace, an external furnace disposed outside the decomposition furnace, the decomposition furnace comprising a conical mixing chamber, a main combustion chamber, a top vortex mixing chamber, and connecting air ducts that are sequentially connected to each other, characterized in that: The bottom of the cone-shaped mixing chamber is connected to the C1 stage air outlet of the preheater, and the side of the cone-shaped mixing chamber is tangentially connected to the air outlet pipe of the external boiler. Several material feeding boxes are installed on the main combustion chamber, and the top vortex mixing chamber is connected to the lowest stage cyclone of the preheater through connecting air pipes.

2. The clay suspension calcination decomposition furnace according to claim 1, characterized in that: The bottom of the cone-shaped mixing chamber is equipped with a circulating air inlet pipe, which includes a vertical pipe and a side pipe. The bottom of the vertical pipe is connected to the exhaust assembly, and the side pipe is connected to the C1 stage air outlet of the preheater.

3. The clay suspension calcination decomposition furnace according to claim 2, characterized in that: The external discharge assembly includes an electric slide gate valve and a flap valve, with the electric slide gate valve positioned above the flap valve.

4. The clay suspension calcination decomposition furnace according to claim 1, characterized in that: The main combustion chamber includes a cylinder, and several material feeding boxes are arranged from top to bottom in the lower part of the cylinder. Burners are arranged in the cylinder near some of the material feeding boxes.

5. The clay suspension calcination decomposition furnace according to claim 1, characterized in that: The swirling direction of the high-temperature flue gas is opposite to the swirling direction of the top vortex mixing chamber.

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