Kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion coupling alternative fuel system
By using a system of alternative fuels coupled with kiln head oxy-rich combustion and kiln tail oxy-rich combustion in the cement industry, the problems of insufficient combustion of alternative fuels and difficulty in temperature control in the pre-burning furnace are solved, more efficient combustion and more stable working conditions are achieved, and subsequent processing costs are reduced.
Patent Information
- Application Number
- CN202510232219.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-05-30
AI Technical Summary
When existing cement companies use alternative fuels, they can easily lead to high chloride ions in clinker products, insufficient combustion of decomposition furnaces, difficulty in temperature control in pre-burning furnaces, and local overtemperature in the furnaces.
A system that uses a system that couples the alternative fuel with oxygen-rich combustion at the kiln head and oxygen-rich combustion at the kiln tail. The oxygen-rich gas is supplied to the rotary kiln and pre-burning furnace through the oxygen-rich gas supply module. Combined with the step structure of the pre-burning furnace and the grate system, the stable feeding and uniform advance of the alternative fuel are achieved, and the fly ash is treated through the bypass air discharge system and the fly ash water washing system.
The combustion efficiency of alternative fuels is improved, the discharge speed is stabilized, local overtemperature in the pre-burning furnace is avoided, the amount of fly ash is reduced, the concentration of chlorine in the ash is increased, and the cost of the washing process is reduced.
Smart Images
Figure CN120062991A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the cement industry, and particularly relates to a system for coupling oxy-fuel combustion at the kiln head and oxy-fuel combustion at the kiln tail to replace fuels. Background Art
[0002] At present, most cement enterprises are prone to problems such as high chloride ion content in clinker products and insufficient combustion in the decomposition furnace after using alternative fuels. Taking waste textile alternative fuels as an example, the calorific value is only 70%-80% of that of coal, the chlorine element is about 140 times that of coal, under the condition of replacing coal with equal heat, the required oxygen amount is 1.13 times that of coal, and the particle size is 1000 times that of coal.
[0003] On the one hand, due to the high chlorine element in the alternative fuel, the chlorine element is cyclically enriched in the decomposition furnace flue gas chamber. In order to break the balance, a bypass air release system generally needs to be equipped. However, the chlorine element in the fly ash generated by the air release is too high, and the treatment price is expensive, further reducing the economy of the alternative fuel. Therefore, the prior art needs to treat the fly ash generated by the air release to reduce the fly ash amount, increase the chlorine element concentration in the ash, and reduce the cost of the subsequent water washing process.
[0004] On the other hand, the alternative fuel has high moisture, unstable quality, slow combustion speed, large oxygen demand, insufficient oxygen supply in the decomposition furnace, and cannot support the full combustion of the alternative fuel in the decomposition furnace, resulting in a large amount of CO at the outlet of the preheater, directly affecting the performance of the alternative fuel. In addition, the transportation structure of the alternative fuel is unreasonable. Using the method of directly injecting the alternative fuel into the decomposition furnace, due to the intermittency of the feeding, the thermal working conditions in the decomposition furnace are prone to instability. Although some cement enterprises currently use pre-combustion furnace systems such as step furnaces and hot plate furnaces to couple with alternative fuels, it also brings problems such as difficult temperature control in the pre-combustion furnace and local overheating in the furnace, seriously affecting the service life of the refractory materials in the furnace and requiring further improvement. Summary of the Invention
[0005] The purpose of the present invention is to provide a system for coupling oxy-fuel combustion at the kiln head and oxy-fuel combustion at the kiln tail to replace fuels, which is used to solve the technical problems in the prior art that during the process of preprocessing alternative fuels and inputting them into the decomposition furnace by the pre-combustion furnace system, there are problems such as unstable feeding, low combustion efficiency in the decomposition furnace, and local overheating in the pre-combustion furnace that easily affects the service life of equipment.
[0006] The system for coupling oxy-fuel combustion at the kiln head and oxy-fuel combustion at the kiln tail to replace fuels includes an oxygen-rich gas supply module, a rotary kiln, a pre-combustion furnace, a decomposition furnace, a bypass air release system, a fly ash water washing system, and a raw meal mill. The oxygen-rich gas supply module supplies oxygen-rich gas to the kiln head of the rotary kiln and the pre-combustion furnace respectively through pipelines. The kiln tail of the rotary kiln is connected to the bottom of the decomposition furnace. The discharge port of the pre-combustion furnace communicates with the bottom cone of the decomposition furnace from the side. The side of the bottom cone is connected to the bypass air release system through a pipeline. The bypass fly ash collected by the bypass air release system is processed by the fly ash water washing system and then transported to the raw meal mill. The raw meal produced by the raw meal mill is transported into the decomposition furnace.
[0007] Preferably, the pre-combustion furnace is divided into three sections from the feed end to the discharge end. The first section is provided with a stepped structure of a stepped furnace, and air cannons are arranged on each step of the stepped structure to jet air towards the discharge end. The second section is provided with a grate system, and the material realizes the uniform advancement of the replacement fuel through the reciprocating movement of the movable grate bars in the grate system. The third section is provided with a stepped structure, and air cannons and thermocouples are arranged at the stepped structure.
[0008] Preferably, the grate system includes a grate structure composed of a number of grate bars. The grate bars include fixed grate bars and movable grate bars. The front end of the movable grate bar is slidably connected to the fixed grate bar. The movable grate bar is installed on the movable grate cross beam through a connecting rod. The grate drive mechanism is connected to the bottom end of the movable grate cross beam, and the grate drive mechanism is connected to the power structure and driven by the power structure to perform reciprocating movement.
[0009] Preferably, the grate system further includes a ventilation structure. The ventilation structure includes a number of air inlets evenly arranged along the extension direction of the second section. The air inlets are communicated with the oxygen-rich gas supply module through air inlet pipelines. The power structure of the grate system is an electric push rod, and the grate drive mechanism is a transmission rod. The transmission rod is axially fixedly connected to the output end of the push rod, and the transmission rod is also fixedly connected to the movable grate cross beam.
[0010] Preferably, the grate system further includes a sealing structure. The sealing structure includes a gasket or a sealing sheet arranged between each grate bar. The sealing structure seals the gap between adjacent grate bars, making it difficult for solid materials to leak from the gap, while the input oxygen-rich gas can enter the space above the grate structure through the gap between the grate bars.
[0011] Preferably, the first section is provided with a spiral auger for inputting replacement fuel and a tertiary air duct at the top of the feed end. In the third section, the thickness of the castable is thickened at the stepped structure, and the thermocouple is arranged 1 - 3 m above the stepped structure.
[0012] Preferably, in the pre - combustion furnace, the range of the number of steps of the stepped structure in the first stage is 3 - 5 levels, and the range of the number of steps of the stepped structure in the third stage is 0 - 2 levels. Along the stepped direction, several layers of grate plates are arranged in the grate structure, the number of layers of the grate plates ranges from 5 to 10 layers, and the angle of the flat part of the grate plate relative to the horizontal plane ranges from 15° to 25°.
[0013] Preferably, a cyclone separator is provided between the conical part of the decomposition furnace and the bypass air bleed system. The gas outlet of the cyclone separator is connected to the bypass air bleed system, the solid outlet of the cyclone separator is connected to the decomposition furnace, and the inlet of the cyclone separator is connected to the conical part.
[0014] Preferably, the oxygen - enriched gas supply module includes an oxygen - making system and an oxygen mixer. Through pipelines, a part of the oxygen - enriched gas passes through the oxygen mixer and is mixed with the air input from the outside to form a re - mixed oxygen - enriched gas within a certain oxygen concentration range. Then, the re - mixed oxygen - enriched gas is transported through pipelines to the inlet of the primary air fan at the kiln head, and after being pressurized by the primary air fan, it is sent into the rotary kiln.
[0015] Preferably, the oxygen - making system produces oxygen - enriched gas with an oxygen concentration of ≥80%. The oxygen - making method adopted by the oxygen - making system is any one of cryogenic method, vacuum pressure swing adsorption or membrane method; the oxygen concentration of the re - mixed oxygen - enriched gas is within the range of 30 - 45%.
[0016] The advantages of the present invention are as follows: In the first stage of the pre - combustion furnace of the present invention, the feeding speed of the alternative fuel can be controlled and the tertiary air is introduced. Since the oxygen content provided by the tertiary air is insufficient, the alternative fuel mainly undergoes drying and partial pyrolysis on the upper steps, preventing a significant increase in temperature caused by the full combustion of the alternative fuel. In the subsequent second stage, oxygen - enriched gas with a certain concentration is supplied into the system from below the grate. The oxygen - enriched gas enters the furnace interior through the gaps between the grate plates through an independent air chamber, providing an oxygen - enriched environment for the pre - combustion furnace while cooling the grate plates. At the same time, the grate structure can drive the alternative fuel to move forward continuously and evenly through the reciprocating movement of the grate plates. In this way, the feeding speed of the alternative fuel can be further stabilized, ensuring the continuous and stable feeding of the alternative fuel into the decomposition furnace and reducing the adverse impact of feeding fluctuations on the thermal working conditions of the decomposition furnace. In the third stage of the present invention, the thickness of the castable is thickened, which can prevent local high - temperature points from being generated by the thermal radiation of the decomposition furnace at the connection part with the decomposition furnace, avoiding damage to the mechanical structure of the pre - combustion furnace; at the same time, through the temperature - measuring function of the thermocouple at this place, when it overheats here, the system will increase the blowing speed of the air cannon and the reciprocating pushing speed of the grate furnace, shortening the residence time of the alternative fuel in the pre - combustion furnace and avoiding over - burning in the pre - combustion furnace.
[0017] In addition, the present invention also realizes the addition of oxygen-rich gas to the kiln head and the kiln tail (supplementing oxygen-rich gas to the kiln tail through a pre-combustion furnace), improves the calcination capacity in the rotary kiln, alleviates the problem of oxygen deficiency in the decomposition furnace, and at the same time accelerates the combustion of alternative fuels by increasing the temperature of the tertiary air entering the decomposition furnace.
[0018] The setting of the bypass air release system and the fly ash water washing system can realize the treatment and reuse of bypass fly ash. The cyclone separator arranged between the bypass air release system and the decomposition furnace can extract large particle ash in the flue gas for separation and re-send it into the decomposition furnace, achieving the effects of reducing the fly ash amount, increasing the chlorine element concentration in the ash, and reducing the cost of subsequent water washing processes. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic flow diagram of the system for coupling alternative fuels by oxygen-enriched combustion at the kiln head and oxygen-enriched combustion at the kiln tail of the present invention.
[0020] Figure 2 It is a schematic structural diagram of the pre-combustion furnace and the decomposition furnace of the present invention.
[0021] Figure 3 It is a schematic internal structural diagram of the second stage of the pre-combustion furnace of the present invention.
[0022] The reference numerals in the drawings include: 1, decomposition furnace; 2, tertiary air duct; 3, spiral auger; 4, first stage; 5, second stage; 51, fixed grate bars; 52, movable grate bars; 53, movable grate cross beam; 54, transmission rod; 55, electric push rod; 56, air inlet; 6, third stage; 7, air cannon. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0023] The following further describes the specific embodiments of the present invention in detail with reference to the drawings through the description of the embodiments, so as to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.
[0024] As Figures 1 to 3 shown, the present invention provides a system for coupling alternative fuels by oxygen-enriched combustion at the kiln head and oxygen-enriched combustion at the kiln tail, including an oxygen-rich gas supply module, a rotary kiln, a pre-combustion furnace, a decomposition furnace 1, a bypass air release system, a fly ash water washing system and a raw material mill. The oxygen-rich gas supply module supplies oxygen-rich gas to the kiln head of the rotary kiln and the pre-combustion furnace respectively through pipelines. The kiln tail of the rotary kiln is connected to the bottom of the decomposition furnace 1. The discharge port of the pre-combustion furnace is connected to the bottom cone of the decomposition furnace 1 from the side. The side of the bottom cone is connected to the bypass air release system through a pipeline. The bypass fly ash collected by the bypass air release system is processed by the fly ash water washing system and then transported to the raw material mill. The raw material produced by the raw material mill is transported into the decomposition furnace 1.
[0025] The pre - combustion furnace is divided into three sections from the feed end to the discharge end. The first section 4 is provided with a stepped structure of a stepped furnace. On each step of the stepped structure, an air cannon 7 is provided to jet air towards the discharge end. The second section 5 is provided with a grate system. The material realizes the uniform advancement of the alternative fuel through the reciprocating movement of the movable grate bars 52 in the grate system. The third section 6 is provided with a stepped structure, and an air cannon 7 and a thermocouple are provided at the stepped structure.
[0026] The first section 4 is provided with a screw auger 3 for inputting alternative fuel and a tertiary air duct 2 located at the top of the feed end. The tertiary air duct 2 introduces part of the tertiary air to enter from above the pre - combustion furnace. The screw auger 3 can control the feeding speed of the alternative fuel. During operation, in the first section 4, after the alternative fuel enters the pre - combustion furnace, it preferentially accumulates on the steps. The alternative fuel is sprayed into the next lower step or the lower area through the regularly operating air cannon 7. Due to the insufficient oxygen content provided by the tertiary air, the alternative fuel mainly undergoes drying and partial pyrolysis on the upper steps, preventing a significant increase in temperature caused by the full combustion of the alternative fuel.
[0027] The grate system includes a grate structure composed of several grate bars. The grate bars include fixed grate bars 51 and movable grate bars 52. The front end of the movable grate bar 52 is slidably connected to the fixed grate bar 51. The movable grate bar 52 is installed on the movable grate cross - beam 53 through a connecting rod. The grate drive mechanism is connected to the bottom end of the movable grate cross - beam 53, and the grate drive mechanism is connected to the power structure and driven by the power structure to perform reciprocating motion.
[0028] The grate bars are made of alloy steel with high temperature resistance, wear resistance and good oxidation resistance, such as steel containing alloy elements such as chromium, nickel, molybdenum, etc. These elements can significantly improve the high - temperature strength, hardness and oxidation resistance of the steel, ensuring that the grate bars will not be damaged due to high - temperature deformation, excessive wear or corrosion during the long - term combustion process, thus ensuring the normal operation and service life of the grate furnace.
[0029] The grate system also includes a ventilation structure. The ventilation structure includes a number of air inlets 56 evenly arranged along the extension direction of the second section 5. The air inlets 56 are connected to the oxygen - enriched gas supply module through an intake pipeline. The air inlets 56 are located below the grate structure. In this way, a certain concentration of oxygen - enriched gas is simultaneously supplied to enter the system from below the grate. The oxygen - enriched gas enters the furnace interior through the gaps between the grate bars from the independent air chamber, while cooling the grate bars, providing an oxygen - enriched environment for the pre - combustion furnace, and indirectly supplementing oxygen to the calciner 1 system.
[0030] The grate system also includes a combustion structure. The combustion structure includes the furnace chamber and refractory materials in the second section 5. The interior of the furnace chamber provides a space for fuel combustion, and the refractory materials protect the outer wall of the furnace chamber, reducing the heat loss to the surrounding environment and improving the thermal efficiency.
[0031] The grate system further includes a power structure, which is an electric push rod 55. In the electric push rod 55, the motor drives the screw rod to rotate through a speed reducer. The nut on the screw rod is connected to the push rod. The rotation of the screw rod makes the nut move linearly along the screw rod, pushing the push rod to make a reciprocating motion. The grate transmission mechanism is a transmission rod 54, and the transmission rod 54 is fixedly connected coaxially with the output end of the pushing push rod. The transmission rod 54 is also fixedly connected to the movable grate cross beam 53.
[0032] The grate system further includes a sealing structure, which includes gaskets or sealing sheets provided between each grate plate. The sealing structure ensures that the gaps between adjacent grate plates are effectively blocked. While making it difficult for solid materials to leak from the gaps, the input oxygen-rich gas can enter the space above the grate structure through the gaps between the grate plates. The second section 5 also provides an ash hopper below the grate plates to collect the residue of the alternative fuel leaking from the gaps between the grate plates and send it into the decomposition furnace 1 regularly.
[0033] The second section 5 can drive the alternative fuel to move forward continuously and evenly through the reciprocating motion of the grate plates. In this way, the feeding speed of the alternative fuel can be further stabilized, ensuring the continuous and stable feeding of the alternative fuel into the decomposition furnace 1, reducing the adverse impact of the feeding fluctuation on the thermal working conditions of the decomposition furnace 1. At the same time, a certain concentration of oxygen-rich gas is supplied to enter the system from below the grate, cooling the grate plates while providing an oxygen-rich environment for the pre-combustion furnace and indirectly supplementing oxygen to the decomposition furnace 1 system.
[0034] In the third section 6, the thickness of the castable is thickened at the stepped structure, which can prevent local high-temperature points from being generated at the connection part with the decomposition furnace 1 due to the thermal radiation of the decomposition furnace 1 and damage the mechanical structure of the pre-combustion furnace. In the third section 6, in order to control the combustion speed of the alternative fuel, a thermocouple is provided 1-3 m above the stepped structure. When the temperature of the thermocouple exceeds 1050 °C, the system will increase the blowing speed of the air cannon 7 and the reciprocating pushing speed of the grate furnace, shortening the residence time of the alternative fuel in the pre-combustion furnace and avoiding overburning in the pre-combustion furnace.
[0035] A cyclone separator is provided between the conical part of the decomposition furnace 1 and the bypass air extraction system. The gas outlet of the cyclone separator is connected to the bypass air extraction system, the solid outlet of the cyclone separator is connected to the decomposition furnace 1, and the inlet of the cyclone separator is connected to the conical part. In this way, when taking air from the kiln tail smoke chamber into the bypass air extraction system, it can prevent the chlorine element in the alternative fuel from circulating and enriching in the kiln, resulting in kiln tail crusting. At this time, the bypass air volume should be designed according to the chlorine element characteristics of the alternative fuel. Generally, the bypass air volume should be controlled at about 3%-20%. The cyclone separator extracts and separates large particle ash in the flue gas during the bypass air extraction process, and then re-feeds it into the decomposition furnace 1 to reduce the fly ash volume, increase the chlorine element concentration in the ash, and reduce the cost of subsequent water washing process; the separation efficiency of the high-temperature cyclone separator is recommended to be greater than or equal to 80%
[0036] The fly ash water washing system can wash and remove chlorine from the fly ash, control the chlorine content in the fly ash below 2%, and then send it to the raw material mill to be used in combination with the raw material. The raw material produced by the raw material mill is then input into the rotary kiln to realize the reuse of the fly ash, and at the same time solve the problems of difficult disposal of chlorine-removed ash and high outsourcing treatment costs.
[0037] In terms of some system parameters and material selection, specifically as follows: The input amount of the tertiary air into the pre-combustion furnace needs to control the excess air coefficient range in the furnace to be 0.3-0.5 to avoid the too-fast combustion of the alternative fuel in the pre-combustion furnace. In the pre-combustion furnace, the range of the steps of the stepped structure in the first section 4 is 3-5 levels, and the range of the steps of the stepped structure in the third section 6 is 0-2 levels. The grate structure is provided with several layers of grate plates along the stepped direction, the number of layers of the grate plates ranges from 5 to 10 layers, and the angle of the plane part of the grate plate relative to the horizontal plane ranges from 15° to 25°. Two air cannons 7 are provided on each layer of the stepped structure and the stepped structure. For each air cannon 7, the pressure range is 0.4-0.6 MPa, the interval time is set to 5 s, and the cycle time is 100 s. The inner wall of the pre-combustion furnace uses microcrystalline materials as refractory materials to inhibit the growth of furnace lining crusting.
[0038] The oxygen-rich gas supply module includes an oxygen production system and an oxygen mixer. The oxygen production system produces oxygen-rich gas with an oxygen concentration of ≥80%. The oxygen production method adopted by the oxygen production system is any one of cryogenic method, vacuum pressure swing adsorption or membrane method. Through the pipeline, a part of the oxygen-rich gas passes through the oxygen mixer and is mixed with the air input from the outside to form a re-mixed oxygen-rich gas within a certain oxygen concentration range, and then the re-mixed oxygen-rich gas is transported to the inlet of the primary air fan at the kiln head through the pipeline, and after being pressurized by the primary air fan, it is sent into the rotary kiln to realize oxygen-rich combustion at the kiln head and improve the calcination ability in the rotary kiln.
[0039] The above system structure and operation mode can increase the temperature of the secondary air and the tertiary air in the range of 50 - 150 °C, while reducing the excess air coefficient in the rotary kiln, reducing the secondary air volume by 5% - 8%, and increasing the tertiary air volume, so as to supplement the oxygen in the calciner 1 and relieve the problem of oxygen deficiency in the calciner 1. At the same time, the system accelerates the combustion of the alternative fuel by increasing the temperature of the tertiary air entering the calciner 1. The oxygen concentration of the remixed oxygen-enriched gas is in the range of 30 - 45%. During operation, the system also transports the oxygen-enriched gas (oxygen concentration ≥ 80%) to the second section 5 of the pre-combustion furnace through a pipeline, where the oxygen concentration in a local area of the pre-combustion furnace is increased.
[0040] The present invention has been described exemplarily above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the inventive concept and technical solution of the present invention, or the inventive concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.
Claims
1. A system of coupling alternative fuels with oxygen-enriched combustion at the kiln head and oxygen-enriched combustion at the kiln tail, characterized by: The invention comprises an oxygen-enriched gas supply module, a rotary kiln, a precombustion furnace, a decomposition furnace (1), a bypass venting system, a fly ash washing system and a raw meal mill. The oxygen-enriched gas supply module supplies oxygen-enriched gas to the kiln head of the rotary kiln and the precombustion furnace through pipelines respectively. The kiln tail of the rotary kiln is connected to the bottom of the decomposition furnace (1). The discharge port of the precombustion furnace is connected to the bottom cone of the decomposition furnace (1) from the side. The side of the bottom cone is connected to the bypass venting system through a pipeline. The bypass fly ash collected by the bypass venting system is processed by the fly ash washing system and then transported to the raw meal mill. The raw meal produced by the raw meal mill is transported to the decomposition furnace (1).
2. The system of coupling alternative fuels of oxygen-enriched combustion at the kiln head and oxygen-enriched combustion at the kiln tail according to claim 1 is characterized in that: The pre-combustion furnace is divided into three sections from the feeding end to the discharging end. The first section (4) is provided with a stepped structure of a stepped furnace. An air cannon (7) is provided on each step of the stepped structure to spray air toward the discharging end. The second section (5) is provided with a grate system. The material is moved forward at a uniform speed by the reciprocating motion of the movable grate plates (52) in the grate system. The third section (6) is provided with a step structure and an air cannon (7) and a thermocouple are provided at the step structure.
3. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 2 is characterized in that: The grate system comprises a grate structure composed of a plurality of grate plates, wherein the grate plates comprise fixed grate plates (51) and movable grate plates (52), the front end of the movable grate plates (52) being slidably connected to the fixed grate plates (51), the movable grate plates (52) being mounted on movable grate cross beams (53) via connecting rods, the grate transmission mechanism being connected to the bottom end of the movable grate cross beam (53), and the grate transmission mechanism being connected to a power structure and being driven by the power structure to perform reciprocating motion.
4. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 3 is characterized in that: The grate system also includes a ventilation structure, which includes a plurality of air inlets (56) evenly arranged along the extension direction of the second section (5), and the air inlets (56) are connected to the oxygen-enriched gas supply module through an air intake pipe; the power structure of the grate system is an electric push rod (55), and the grate transmission mechanism is a transmission rod (54), and the transmission rod (54) is coaxially fixedly connected to the output end of the push rod, and the transmission rod (54) is also fixedly connected to the movable grate cross beam (53).
5. The system of coupling alternative fuels of oxygen-enriched combustion at the kiln head and oxygen-enriched combustion at the kiln tail according to claim 3 is characterized in that: The grate system also includes a sealing structure, which includes sealing pads or sealing sheets arranged between each grate sheet; the sealing structure blocks the gaps between adjacent grate sheets, making it difficult for solid materials to leak from the gaps, while the input oxygen-rich gas can enter the space above the grate structure through the gaps between the grate sheets.
6. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 2 is characterized in that: The first section (4) is provided with a spiral auger (3) for inputting alternative fuel and a tertiary air duct (2) located at the top of the feed end; in the third section (6), the thickness of the castable is thickened at the step structure, and the thermocouple is arranged 1-3m above the step structure.
7. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 2 is characterized in that: In the pre-combustion furnace, the step structure of the first section (4) is provided with steps ranging from 3 to 5, and the step structure of the third section (6) is provided with steps ranging from 0 to 2. The grate structure is provided with a plurality of layers of grate plates along the step direction, the number of layers of the grate plates is ranging from 5 to 10, and the angle of the plane part of the grate plates relative to the horizontal plane is set in the range of 15° to 25°.
8. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 1 is characterized in that: A cyclone separator is provided between the conical part of the decomposition furnace (1) and the bypass venting system, the gas outlet of the cyclone separator is connected to the bypass venting system, the solid outlet of the cyclone separator is connected to the decomposition furnace (1), and the inlet of the cyclone separator is connected to the conical part.
9. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 1 is characterized in that: The oxygen-enriched gas supply module includes an oxygen production system and an oxygen mixer. Through pipelines, a part of the oxygen-enriched gas passes through the oxygen mixer and is mixed with air input from the outside to form remixed oxygen-enriched gas within a certain oxygen concentration range. The remixed oxygen-enriched gas is then transported to the primary air fan inlet at the kiln head through the pipeline and is pressurized by the primary air fan before being sent to the rotary kiln.
10. The system of coupling alternative fuels of kiln head oxygen-enriched combustion and kiln tail oxygen-enriched combustion according to claim 1 is characterized in that: The oxygen production system produces oxygen-rich gas with an oxygen concentration of ≥80%. The oxygen production method adopted by the oxygen production system is any one of cryogenic method, vacuum pressure swing adsorption or membrane method; the oxygen concentration of the mixed oxygen-rich gas is within the range of 30-45%.