A system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber

Abstract

The present invention discloses a system for treating biomass waste using exhaust gas from a kiln tail flue chamber, belonging to the field of cement clinker manufacturing. The system comprises a rotary kiln 1, a flue chamber 2, a high-temperature flue chamber air duct 3, a biomass feed port 4, a raw meal feed port 5, a mixed combustion chamber 6, a compressed air purge device 7, a decomposition furnace 8, a cement kiln tertiary air duct 9, a C1 cyclone 14, a C2 cyclone 13, a C3 cyclone 12, a C4 cyclone 11, and a C5 cyclone 10. The present invention utilizes this system to contact raw material carbonate and biomass with the high-temperature exhaust gas from the kiln tail flue chamber, rotary-cutting them and transporting them into the mixed combustion chamber. The system then performs biomass drying, pyrolysis, and product gas-solid separation in a separate chamber. The biomass, leveraging the high enthalpy and low oxygen concentration of the flue chamber exhaust, undergoes pyrolysis under anoxic conditions to generate reducing gases. The products, when introduced into the decomposition furnace, effectively reduce nitrogen oxide concentrations. This system achieves a dual path of replacing coal with biomass combustion and reducing nitrogen oxide emissions.

Description

Technical Field

[0001] The present invention relates to the field of cement clinker manufacturing, and in particular to a system for treating biomass waste by utilizing waste gas from a kiln tail smoke chamber. Background Art

[0002] The industry has proposed a grate furnace + decomposition furnace technology for solid waste disposal, such as Figure 4 As shown: After simple dehydration, the solid waste is sent to the grate furnace for incineration. The solid waste is evenly distributed on the inclined grate, and the material is passively moved forward by the displacement between the moving grates. Primary air is introduced into the bottom of the device. After being preheated to 200-250℃, the primary air is continuously transported to the surface of the solid waste through the gaps between the grate hearth. Its main function is to slowly dry, heat, and ignite the accumulated materials. This heat treatment process uses the ratio of combustion-supporting air and the movement of the grate device to control the combustion temperature and the residence time of the solid waste disposal, with the aim of achieving pyrolysis of the solid waste as much as possible. The flue gas generated by the heated combustion of the solid waste in the grate furnace is sent to the decomposition furnace through the thermal pipeline for disposal. The remaining slag is cooled by water quenching and sent to the raw mill to replace part of the raw materials.

[0003] Although the industry has already used grate furnace + decomposition furnace technology to dispose of solid waste, the above technology has the following disadvantages:

[0004] ① The system uses cold air preheating to heat the gas. The combustion-supporting gas consumes additional system energy, and the air temperature after preheating is not high, which limits the utilization of solid waste heat in the system.

[0005] ② This technology suffers from low thermal efficiency. After solid waste is thermally decomposed, residue forms on the grate surface. This residue, with its high enthalpy, cannot be returned to the preheater system for reuse, requiring only water quenching for removal, resulting in a waste of calorific value. Furthermore, the flue gas generated by solid waste decomposition is introduced into the decomposition furnace via thermal piping. Heat dissipation occurs on the piping surface, leading to heat loss and reduced thermal efficiency.

[0006] ③ Incomplete solid waste combustion and long residence time. Solid waste is piled on the grate surface. Drying and ignition rely on the combined heat release of primary air and flame combustion. However, solid waste ignition and combustion only occur in a limited shallow space. The combustion of the surface solid waste can only be transferred to the lower layer after decomposition. Therefore, the disposal is subject to incomplete combustion and theoretically requires a longer residence time to achieve complete burnout. Summary of the Invention

[0007] The present invention aims to provide a system for treating biomass waste using waste gas from the kiln tail flue chamber. This system is a cement kiln co-treatment system for domestic waste. Biomass is transported to the high-temperature gas environment of the kiln tail flue chamber for pyrolysis, and then returned to the decomposition furnace for combustion. This system can improve the co-treatment capacity of cement kilns and address the following key issues in the prior art:

[0008] ① Design an online and efficient biomass disposal device next to the cement kiln decomposition furnace, using the high-temperature gas emitted from the smoke chamber of the cement industry production process as a heat source to incinerate the urban and rural domestic waste fed into it.

[0009] ② Establish an independent mixing combustion chamber as a space for biomass thermal decomposition, disperse the materials, accelerate the preheating, drying and predecomposition process of the materials, and improve the stability of the preheating and predecomposition system.

[0010] ③ Along with the biomass disposal process, a reducing atmosphere is generated in the combustion device, and the reducing gas is introduced into the decomposition furnace to achieve nitrogen oxide emission reduction, providing a denitrification method for the decomposition furnace.

[0011] To achieve the above objectives, the present invention provides the following technical solutions:

[0012] A system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber comprises a rotary kiln, a smoke chamber, a high-temperature air duct in the smoke chamber, a biomass feeding port, a raw meal feeding port, a mixed combustion chamber, a compressed air purge device, a decomposition furnace, a cement kiln tertiary air duct, a C1 cyclone, a C2 cyclone, a C3 cyclone, a C4 cyclone, and a C5 cyclone.

[0013] Furthermore, the smoke chamber is the connecting part between the rotary kiln and the decomposition furnace, the smoke chamber inlet is connected to the rotary kiln, and the smoke chamber outlet is connected to the smoke chamber high-temperature air duct.

[0014] Furthermore, the smoke chamber high-temperature air duct is arranged with a raw material feeding port at the front end and a biomass feeding port at the rear end. The smoke chamber high-temperature air duct is connected to the mixed combustion chamber, and the high-temperature exhaust gas from the smoke chamber is conducted to the mixed combustion chamber through the duct.

[0015] Furthermore, the upper part of the mixing combustion chamber is cylindrical, and the high-temperature gas from the smoke chamber carries the raw material and biomass solid components into the mixing combustion chamber in a side-cutting manner. The material moves downward in a continuous swirling flow and is accompanied by a thermal decomposition process; the lower part is conical, which separates the flue gas and the decomposed ash.

[0016] Furthermore, the bottom of the mixing combustion chamber is a sloped structure, which is connected to the decomposition furnace in a downward slanting manner. A compressed air purge device is provided outside the sloped structure. The purpose of setting up this device is to promptly flow the mixture accumulated on the slope into the decomposition furnace by blowing air.

[0017] Furthermore, the feed port of the C4 cyclone is connected to the discharge port of the C3 cyclone, the feed pipe is connected to the decomposition furnace, and its outlet is connected to the feed port of the C3 cyclone.

[0018] Furthermore, the C5 cyclone is connected to the top of the decomposition furnace, the discharge pipe of the C5 cyclone is connected to the smoke chamber, and the air outlet of C5 is connected to the feed port of the C4 cyclone.

[0019] Furthermore, the feed port of the C3 cyclone is connected to the discharge port of the C2 cyclone, and its air outlet is connected to the feed port of the C2 cyclone.

[0020] Furthermore, the C2 cyclone has its feed port connected to the discharge port of the C1 cyclone, and its air outlet is connected to the feed port of the C1 cyclone.

[0021] Furthermore, the feed port of the C1 cyclone is connected to the air outlet of the C2 cyclone.

[0022] The present invention is based on the above technical solution and has the following advantages:

[0023] ①The disposal system uses the thermal enthalpy of the high-temperature exhaust gas in the kiln tail smoke chamber to achieve biomass combustion, which can ensure that most organic matter reacts stably in the mixed combustion chamber, so that it can be completely decomposed and burned to release heat after entering the decomposition furnace.

[0024] ② The biomass moves continuously downward in the mixing combustion chamber in a swirling state, which not only ensures the dispersion of the materials, but also achieves a rapid drying and dehydration effect with the help of high-temperature exhaust gas and full contact with the moisture in the biomass, ensuring that the garbage is burned as soon as possible after entering the decomposition furnace to release heat.

[0025] ③ Because the oxygen content of the high-temperature exhaust gas in the smoke chamber is low, the biomass undergoes a pyrolysis and gasification process after full contact with it in the mixed combustion chamber, accompanied by the production of reducing gaseous volatiles such as CO and H2. The flue gas rich in reducing atmosphere is passed into the decomposition furnace, which helps to achieve self-denitrification and reduce nitrogen oxide emissions.

[0026] Raw meal and biomass are mixed in the combustion chamber. On the one hand, the carbonate decomposition of raw meal and the pyrolysis of biomass are endothermic processes, which can effectively control the temperature in the mixed combustion chamber. On the other hand, the raw meal wraps the biomass to avoid crusting on the surface of the chamber, making it easier to transport the material to the decomposition furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0028] Figure 2 It is a structural diagram of an embodiment of the present invention;

[0029] Figure 3 It is a structural diagram of an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of a grate furnace + calciner in the industry;

[0031] In the figure: 1. Rotary kiln; 2. Smoke chamber; 3. Smoke chamber high-temperature air duct; 4. Biomass feeding port; 5. Raw meal feeding port; 6. Mixing combustion chamber; 7. Compressed air purge device; 8. Decomposition furnace; 9. Cement kiln tertiary air duct; 10. C5 cyclone; 11. C4 cyclone; 12. C3 cyclone; 13. C2 cyclone; 14. C1 cyclone. DETAILED DESCRIPTION

[0032] The present invention provides a system for treating biomass waste by utilizing waste gas from the kiln tail smoke chamber. Figure 1 , a system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber of the present invention is described in further detail.

[0033] A system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber, comprising a rotary kiln 1, a smoke chamber 2, a mixed combustion chamber 6, a decomposition furnace 8, and a C1 cyclone 14, a C2 cyclone 13, a C3 cyclone 12, a C4 cyclone 11, and a C5 cyclone 10. The smoke chamber 2 is the connecting part between the rotary kiln 1 and the biomass waste system, the inlet of the smoke chamber 2 is connected to the rotary kiln 1, and the outlet of the smoke chamber 2 is connected to the smoke chamber high-temperature air duct 3. A raw material feeding port 5 is arranged at the front end of the smoke chamber high-temperature air duct 3, and a biomass feeding port 4 is arranged at the rear end of the smoke chamber high-temperature air duct 3. The other end of the smoke chamber high-temperature air duct 3 is connected to the mixed combustion chamber 6, and the mixed combustion chamber 6 is connected to the decomposition furnace 8.

[0034] The upper part of the mixing combustion chamber 6 is cylindrical. The high-temperature gas from the smoke chamber carries the raw material and biomass solid components into the mixing combustion chamber in a side-cutting manner. The material moves downward in a continuous swirling flow and is accompanied by a thermal decomposition process; the lower part is conical, which separates the flue gas and decomposed ash.

[0035] The bottom of the mixing combustion chamber 6 is a sloped structure, and is connected to the decomposition furnace 8 in an oblique downward manner.

[0036] A compressed air blowing device 7 is provided outside the slope structure, and the compressed air blowing device 7 timely flows the mixture accumulated on the slope structure into the decomposition furnace 8 by blowing air.

[0037] The upper part of the decomposition furnace 8 is connected to the exhaust gas duct at the top of the mixing combustion chamber 6; the middle part of the decomposition furnace 8 is connected to the slope at the bottom of the mixing combustion chamber 6; the lower part of the decomposition furnace 8 is connected to the tertiary air duct 9 of the cement kiln, and the bottom of the decomposition furnace 8 is connected to the smoke chamber 2 through a pipeline.

[0038] The C4 cyclone 11, the feed port of the C4 cyclone 11 is connected to the discharge port of the C3 cyclone 12, the discharge pipe is connected to the decomposition furnace 8, and its outlet is connected to the feed port of the C3 cyclone 12.

[0039] The C5 cyclone 10 is connected to the top of the decomposition furnace 8 , the discharge pipe of the C5 cyclone 10 is connected to the smoke chamber 2 , and the air outlet of the C5 cyclone 10 is connected to the feed port of the C4 cyclone 11 .

[0040] The feed port of the C3 cyclone 12 is connected to the discharge port of the C2 cyclone 13 , and the air outlet thereof is connected to the feed port of the C2 cyclone 13 .

[0041] The feed port of the C2 cyclone 13 is connected to the discharge port of the C1 cyclone 14 , and the air outlet thereof is connected to the feed port of the C1 cyclone 14 .

[0042] The feed port of the C1 cyclone 14 is connected to the air outlet of the C2 cyclone 13 . Specific embodiments

[0043] like Figure 1 As shown, the system brings raw carbonate and biomass into contact with high-temperature exhaust gas from the kiln tail smoke chamber, and transports them into the mixed combustion chamber by rotary cutting to achieve biomass drying, pyrolysis, product gas-solid separation and other processes in a separate chamber.

[0044] The smoke chamber 2 is the connecting part between the rotary kiln 1 and the decomposition furnace 8. The smoke chamber inlet is connected to the rotary kiln 1, and the smoke chamber 2 outlet is connected to the smoke chamber high-temperature air duct 3. The temperature of the high-temperature exhaust gas entering the flue gas is 1200℃.

[0045] The smoke chamber high-temperature air duct 3 is connected to the mixing and combustion chamber 6. The high-temperature exhaust gas from the smoke chamber 2 is conducted into the mixing and combustion chamber 6 through this duct. A raw material feeding port 5 is arranged at the front end of the smoke chamber high-temperature air duct 3, and a biomass feeding port 4 is arranged at the rear end. Both biomass and raw material are transported to the mixing and combustion chamber 6 in the direction of the high-temperature exhaust gas flow.

[0046] The side inlet of the mixing combustion chamber 6 is connected to the high-temperature air duct 3 of the smoke chamber, ensuring that the airflow and mixed materials in the air duct are cut and then introduced from the edge of the combustion chamber. The top of the mixing combustion chamber 6 is the outlet for the mixed high-temperature exhaust gas generated after the decomposition of raw materials and the pyrolysis of solid waste. This exhaust gas is connected to the decomposition furnace 8 through a pipeline. The bottom of the mixing combustion chamber 6 is the outlet for the ash after the reaction of the mixture. The bottom is a sloped structure, connected to the decomposition furnace 8 in a downward-facing manner. A compressed air purge device 7 is installed on the outside of the slope. The purpose of this device is to use air to promptly introduce the mixture accumulated on the slope into the decomposition furnace 8.

[0047] The reaction process in the mixed combustion chamber 6 can be divided into: the raw material carbonate decomposes under high temperature conditions to generate CO2 gas; the biomass is quickly dried and dehydrated, and part of the material is pyrolyzed and gasified to produce reducing gaseous volatiles such as CO and H2. The upper part of the mixed combustion chamber 6 is cylindrical. The high-temperature gas from the smoke chamber 2 carries the raw material and biomass solid components into the mixed combustion chamber 6 in a side-peeling manner. The material continuously swirls downward, and the solid material is dispersed and fully contacts the high-temperature gas, undergoing a thermal decomposition process. The lower part is conical, which separates the flue gas and the decomposed ash. The final reducing flue gas leaves from the top of the mixed combustion chamber 6, and the ash produced by the decomposition of the material leaves from the bottom of the mixed combustion chamber 6, and both enter the decomposition furnace 8.

[0048] The top of the decomposition furnace 8 is connected to the C4 cyclone 11, and the gas-solid mixture enters the C4 cyclone 11 through a pipeline to achieve separation; the upper part of the decomposition furnace 8 is connected to the exhaust gas duct at the top of the mixing combustion chamber 6, and the duct is used to transport the smoke chamber exhaust gas, raw material carbonate decomposition gas, and biomass pyrolysis reducing gas to the decomposition furnace to ensure the gas volume in the furnace and stabilize the system operation; the middle part of the decomposition furnace 8 is connected to the slope at the bottom of the mixing combustion chamber 6, and some of the completely dried but pyrolyzed biomass is introduced into the decomposition furnace through the slope to achieve rapid combustion and release energy for system heat utilization; the lower part of the decomposition furnace 8 is connected to the tertiary air duct 9 of the cement kiln; the bottom of the decomposition furnace 8 is connected to the smoke chamber 2 through a pipeline, and the ash produced in the decomposition furnace 8 can enter the smoke chamber 2 through the pipeline to avoid material accumulation at the bottom of the furnace.

[0049] The feed port of the C4 cyclone 11 is connected to the discharge port of the C3 cyclone 12 , and the discharge pipe is connected to the decomposition furnace 8 , and its gas outlet is connected to the feed port of the C3 cyclone 12 .

[0050] The C5 cyclone 10 is connected to the top of the decomposition furnace 8 , the discharge pipe of the C5 cyclone 10 is connected to the smoke chamber 2 , and the air outlet of the C5 cyclone 10 is connected to the feed port of the C4 cyclone 11 .

[0051] The feed port of the C3 cyclone 12 is connected to the discharge port of the C2 cyclone 13, and its air outlet is connected to the feed port of the C2 cyclone 13. The feed port of the C2 cyclone 13 is connected to the discharge port of the C1 cyclone 14, and its air outlet is connected to the feed port of the C1 cyclone 14. The feed port of the C1 cyclone 14 is connected to the air outlet of the C2 cyclone 13.

[0052] In the system, the biomass takes advantage of the high enthalpy value and low oxygen concentration of the smoke chamber exhaust gas to pyrolyze and generate reducing gas under oxygen-deficient conditions. After the product is passed into the decomposition furnace, it can effectively reduce the concentration of nitrogen oxides in the furnace. This disposal method ultimately achieves a dual path of biomass combustion replacing coal and reducing nitrogen oxide emissions.

Claims

1. A system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber, comprising a rotary kiln (1), characterized in that: The invention also includes a smoke chamber (2), a mixed combustion chamber (6) and a decomposition furnace (8), wherein the smoke chamber (2) is a connecting portion between the rotary kiln (1) and the decomposition furnace (8), the inlet of the smoke chamber (2) is connected to the rotary kiln (1), the outlet of the smoke chamber (2) is connected to the smoke chamber high-temperature air duct (3), the front end of the smoke chamber high-temperature air duct (3) is arranged with a raw material feeding port (5), the rear end of the smoke chamber high-temperature air duct (3) is arranged with a biomass feeding port (4), the other end of the smoke chamber high-temperature air duct (3) is connected to the mixed combustion chamber (6), and the mixed combustion chamber (6) is connected to the decomposition furnace (8); ... The bottom of the chamber (6) is a sloped structure, which is connected to the decomposition furnace (8) in an oblique downward manner; a compressed air purge device (7) is provided outside the sloped structure, and the compressed air purge device (7) promptly flows the mixture accumulated on the sloped structure into the decomposition furnace (8) by blowing air; the upper part of the decomposition furnace (8) is connected to the exhaust gas duct at the top of the mixing combustion chamber (6); the middle part of the decomposition furnace (8) is connected to the bottom slope of the mixing combustion chamber (6); the lower part of the decomposition furnace (8) is connected to the tertiary air duct (9) of the cement kiln, and the bottom of the decomposition furnace (8) is connected to the smoke chamber (2) through a pipeline.

2. The system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber according to claim 1, characterized in that: The upper part of the mixed combustion chamber (6) is cylindrical, and the high-temperature gas from the smoke chamber carries the raw material and biomass solid components into the mixed combustion chamber in a side rotary cutting manner. The materials move downward in a continuous swirling flow and are accompanied by a thermal decomposition process; the lower part is conical, which separates the flue gas and the decomposed ash.

3. The system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber according to claim 1, characterized in that: It also includes a C4 cyclone (11), the feed port of the C4 cyclone (11) is connected to the discharge port of the C3 cyclone (12), and the discharge pipe is connected to the decomposition furnace (8), and the gas outlet is connected to the feed port of the C3 cyclone (12).

4. The system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber according to claim 1, characterized in that: It also includes a C5 cyclone (10), which is connected to the top of the decomposition furnace (8), a discharge pipe of the C5 cyclone (10) is connected to the smoke chamber (2), and an air outlet of the C5 cyclone (10) is connected to the feed port of the C4 cyclone (11).

5. The system for treating biomass waste by utilizing exhaust gas from a kiln tail smoke chamber according to claim 1 is characterized in that: It also includes a C1 cyclone (14), a C2 cyclone (13), and a C3 cyclone (12), wherein the feed port of the C3 cyclone (12) is connected to the discharge port of the C2 cyclone (13), and its air outlet is connected to the feed port of the C2 cyclone (13), the feed port of the C2 cyclone (13) is connected to the discharge port of the C1 cyclone (14), and its air outlet is connected to the feed port of the C1 cyclone (14), and the feed port of the C1 cyclone (14) is connected to the air outlet of the C2 cyclone (13).

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