Bypass dust and nitrogen heat integrated treatment system and control method

Abstract

The present application belongs to the technical field of denitration and dust removal device, and discloses a bypass air release dust and nitration integrated treatment system and a control method. The system comprises a rotary kiln, a decomposition furnace connected with the kiln tail of the rotary kiln, and a chimney. A bypass air release port is arranged at the connection of the rotary kiln and the decomposition furnace. The system further comprises a cooler, a cyclone separator, a dust and nitration integrated treatment device, a mixed air chamber and a waste heat recovery furnace connected between the bypass air release port and the chimney in sequence. The cyclone separator comprises a separation bin body and a control part for controlling the flow of flue gas entering the separation bin body from the cooler. The control part comprises a detection mechanism arranged in a flue gas treatment gas path formed by the cooler, the cyclone separator and the dust and nitration integrated treatment device, and an air inlet chamber arranged on the air inlet of the separation bin body and a first gate installed on the air inlet chamber for controlling the opening degree of the air inlet of the separation bin body. The system is optimized in integrated design to realize compact process flow, reduce operation energy consumption and operation and maintenance cost.

Description

Technical Field

[0001] This invention belongs to the technical field of denitrification and dust removal devices, and specifically relates to a bypass venting dust, nitrification and heat integrated treatment system and control method. Background Technology

[0002] The cement industry reduces carbon emissions by co-processing municipal solid waste (household waste, sludge, and hazardous waste) and increasing the use of alternative fuels (AFRs). However, as the cement industry continues to increase its co-processing of solid waste and the substitution rate of alternative fuels, the enrichment effect of volatile harmful elements such as chlorine, sulfur, and alkali in the calcination system becomes increasingly significant. This easily induces scaling and blockage in preheaters and decomposition furnaces, severely restricting the stability of clinker production and quality. Therefore, using bypass venting technology to extract, rapidly cool, and remove high-temperature flue gas is a necessary means to prevent the cyclic enrichment of harmful elements.

[0003] Current industry standards require that the hourly average concentration of nitrogen oxide emissions from cement kilns not exceed 50 mg / m³. 3 Because the flue gas generated by bypass venting itself has a high NOx concentration, under stringent emission limits, existing bypass venting systems without denitrification are often forced to reduce venting volume to avoid exceeding emission standards. This, in turn, severely restricts the large-scale use of alternative fuels. Therefore, in order to meet ultra-low emission standards while achieving a high proportion of alternative fuel substitution, deep denitrification treatment of bypass venting exhaust gas has become an inevitable trend in the industry.

[0004] However, existing cement kiln bypass venting technologies generally employ a "rapid cooling + conventional bag filter" process. Limited by the temperature resistance of ordinary filter bags (such as P84 and PPS), it is necessary to cool the venting gas, which is around 1100℃, to 200℃ or even lower by mixing in a large amount of cold air. This approach has significant technical drawbacks: First, energy utilization efficiency is low, as the high-grade sensible heat in the 400℃ to 200℃ range of the flue gas is wasted, and effective waste heat recovery is impossible. Second, the SCR denitrification tower, installed to meet ultra-low emission standards, increases floor space and investment costs; moreover, in the high-dust, high-chlorine, and high-alkali environment of the bypass venting gas, the SCR catalyst is highly susceptible to poisoning and wear. Finally, the system coupling stability is poor; the returned low-temperature gas after treatment easily disrupts the system's pressure and temperature balance, even exceeding its capacity. Furthermore, the complex pipeline layout and high system operating resistance significantly increase fan power consumption.

[0005] Therefore, the industry urgently needs a short-process treatment technology that can take into account both heat recovery and efficient dust removal and denitrification. Summary of the Invention

[0006] The purpose of this invention is to provide a bypass venting dust, nitrogen, and heat integrated treatment system that can control the separation effect of the cyclone separator in a timely manner, thereby achieving efficient dust removal, denitrification, and waste heat recovery and utilization.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a bypass venting dust-nitrification-heat integrated treatment system, the system comprising a rotary kiln, a decomposition furnace connected to the kiln tail of the rotary kiln, and a chimney, wherein a bypass vent is provided at the connection between the rotary kiln and the decomposition furnace, and the system further comprising a cooler, a cyclone separator, a dust-nitrification integrated treatment device, a mixing chamber, and a waste heat recovery furnace sequentially connected between the bypass vent and the chimney.

[0008] The cyclone separator includes a separation chamber and a control unit for controlling the flow rate of flue gas entering the separation chamber from the cooler. The control unit includes a detection mechanism located in the flue gas treatment gas path formed by the cooler, cyclone separator, and integrated dust and nitrogen oxide treatment device, an air inlet chamber located on the air inlet of the separation chamber, and a first gate installed on the air inlet chamber for controlling the opening degree of the air inlet entering the separation chamber.

[0009] In another embodiment, the detection mechanism includes a detection chamber connected in parallel to the air outlet of the separation chamber, or a detection chamber connected in parallel to the air inlet and air outlet of the separation chamber, a second gate disposed on the detection chamber for controlling the connection or isolation between the detection chamber and the separation chamber, and an online laser detector disposed on the detection chamber for detecting the particulate concentration in the flue gas inside the detection chamber when the detection chamber is isolated from the separation chamber.

[0010] In another embodiment, the cyclone separator further includes a discharge chamber for discharging particulate matter located at the lower end of the separation chamber, an anti-backflow cone located inside the discharge chamber and in the shape of a cone, and a connecting rod connecting the inner circumferential surface of the discharge chamber and the outer circumferential surface of the anti-backflow cone. The upper end of the anti-backflow cone is closed and the lower end is open, and a gap is formed between its outer wall and the inner wall of the discharge chamber to allow particulate matter to descend and airflow to ascend.

[0011] In another embodiment, the distance between the outer peripheral surface of the anti-return cone and the inner peripheral surface of the discharge chamber decreases from top to bottom.

[0012] In another embodiment, the mixing chamber includes a first mixing duct connected between the outlet of the integrated dust and nitrogen oxide treatment device and the inlet of the waste heat recovery furnace, spiral guide vanes disposed within the first mixing duct, and a second mixing duct connected to the first mixing duct. The first mixing duct introduces at least a portion of the hot air discharged from the waste heat recovery furnace into the first mixing duct. The pitch of the guide vanes increases from the outlet of the integrated dust and nitrogen oxide treatment device towards the inlet of the waste heat recovery furnace. The guide vanes are used to mix the gas discharged from the outlet of the integrated dust and nitrogen oxide treatment device and a portion of the hot air discharged from the waste heat recovery furnace in the first mixing duct. Uniform mixing occurs within the pipe; the front section of the guide vanes adopts a high-density, small-pitch design, forcing the fluid to quickly swirl and generate high-intensity shear force, rapidly breaking up two airflow clusters of different temperatures; the rear section smoothly transitions to a low-density, large-pitch design, which, while inducing axial secondary flow to enhance turbulent mixing, effectively widens the flow channel to reduce frictional resistance along the flow path. This, combined with the relatively small flow rate of high-temperature bypass flue gas entering the mixing chamber tangentially, utilizes the tangential kinetic energy of the bypass flue gas to form a vortex core enhancement effect with the guide vanes, driving the gas discharged from the outlet of the integrated dust and nitrogen oxide treatment device to generate a long-path spiral motion. Under the premise of minimizing system pressure loss, this breaks down the hot and cold stratification and achieves homogenization of the flue gas temperature field.

[0013] In another embodiment, an eccentric reducer for preventing particulate matter accumulation is connected to the air inlet of the integrated dust and nitrogen treatment device. The eccentric reducer is connected between the cyclone separator and the integrated dust and nitrogen treatment device. The upper side of the inner wall of the eccentric reducer is horizontal and the lower side is inclined. The diameter of the eccentric reducer increases from one end of the air inlet of the integrated dust and nitrogen treatment device to the other end. By using an eccentric reducer with a flat top and inclined bottom, the stepped dust accumulation dead corner at the bottom of the traditional horizontal pipe is eliminated, ensuring the flow velocity threshold at the bottom of the pipe.

[0014] In another embodiment, the curved section of the connecting pipe between the cyclone separator and the integrated dust and nitrogen oxide treatment device is equipped with an arc-shaped guide plate that matches the curved section; this effectively rectifyes and eliminates the low-speed zone of secondary eddies induced by centrifugal force, thereby reducing the natural dust settling rate inside the pipe by 85%, and extending the stable operation cycle of the system to more than 60 days, and enabling simultaneous maintenance with the kiln system; this not only eliminates the production capacity loss caused by frequent shutdowns for dust removal, but also reduces the cost of manual maintenance.

[0015] In another embodiment, the system further includes a bypass ash hopper connected to the integrated dust and nitrification treatment device.

[0016] The present invention also provides a control method based on the above system, which includes the following steps:

[0017] a. Start the system and use a detection mechanism to detect the concentration and particle size distribution of particulate matter in the flue gas at the inlet or outlet of the cyclone separator, and obtain the corresponding staged removal efficiency η(d) under different opening degrees of the first gate and flue gas velocities. p For the dataset, the hierarchical removal efficiency η(d) p The Theodore-De Paola empirical formula was used to estimate:

[0018]

[0019] Where, d p d represents the particle size of any particle; 50 The particle diameter at which the separation efficiency is 50% is a key indicator for measuring the precision of the separator, also known as d. 50 The smaller the value, the better the particle separation effect of the cyclone separator; based on the classic Lapple model, the physical parameters are set as follows:

[0020] μ: Dynamic viscosity of flue gas (Pa·s), which is temperature-dependent;

[0021] W: Inlet width (m). Due to the obstruction by the baffle, the effective width here is Weff = W·α;

[0022] N e : The effective number of rotations within the cyclone separator (usually 5-10 rotations);

[0023] V in The tangential air velocity at the air inlet (m / s) is obtained from the above formula;

[0024] ρ p Clinker particle density (kg / m³) 3 );

[0025] ρ g Smoke density (kg / m³) 3 );

[0026] Therefore, the formula for calculating the particle size distribution is:

[0027] ;

[0028] The formula for calculating the effective number of rotations of a cyclone separator is:

[0029]

[0030] in

[0031] H: Height of the air inlet;

[0032] L b : The length of the cylindrical section of the cyclone separator;

[0033] L c : The length of the conical section of the cyclone separator;

[0034] b. Based on the first gate opening, wind speed, and graded removal efficiency η(d) in the dataset p The corresponding relationship is used to control the opening of the first gate, thereby adjusting the graded removal efficiency η(d). p ).

[0035] The present invention also provides a control method based on the above system, which includes the following steps:

[0036] A. After the system has been running for a period of time, take out the ash sample from the bypass ash hopper and test the ash sample to establish the mapping relationship between the ash sample components and the separation efficiency;

[0037] B. The system periodically monitors the chloride ion concentration at the ash discharge port of the integrated dust and nitrogen oxide treatment unit; when the chloride concentration in the fine ash is low, it indicates that the separation efficiency of the cyclone separator is insufficient, i.e., the classification particle size d is too low. 50 If the cyclone separator is too large, a large amount of low-chlorine-concentration raw materials and coarse kiln ash particles will not be removed by the cyclone separator and will enter the ceramic filter, diluting the high-purity chlor-alkali ash. This not only increases the amount and cost of hazardous waste disposal but also exacerbates the physical wear of the ceramic filter tubes. In this case, the opening of the first gate can be reduced to decrease the flow area, increase the inlet air velocity, enhance centrifugal force, improve the collection efficiency of coarse particles, reduce the escape of coarse particles, and increase the chlorine concentration of fine ash. When the chlorine concentration of fine ash meets the standard, but the chlor-alkali cycle of the system is not broken, excessively reducing the baffle opening in pursuit of higher separation efficiency will result in the cyclone separator having too small a classifying particle size, and may even begin to collect some coarser chlor-alkali salt crystals. This will cause too much high-chlorine-content chlor-alkali salt to return to the cement kiln with the coarse ash, causing the chlor-alkali components to re-accumulate in the kiln and failing to achieve the purpose of bypass venting to remove harmful elements. Therefore, further analysis of the chlorine content in the cement kiln is needed. If an abnormal increase occurs, the kiln opening needs to be increased to ensure that fine chlor-alkali salts can escape smoothly from the cyclone and enter the back-end collection, thus being truly discharged from the firing system. If no abnormal increase occurs, the kiln opening should be kept unchanged.

[0038] The beneficial effects of this invention are as follows:

[0039] (1) By integrating dust removal and denitrification functions using high-temperature ceramic fiber filter tubes, the reliability and stability of the system under high temperature are improved;

[0040] (2) Increase the temperature of the recovered flue gas, make full use of the surplus capacity of the existing waste heat recovery furnace, increase the waste heat utilization rate, and improve energy utilization efficiency;

[0041] (3) Optimize system integration design to achieve a compact process flow, reduce operating energy consumption and reduce operation and maintenance costs. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the system structure in Example 1;

[0043] Figure 2 This is a schematic diagram of the cyclone separator in Example 1;

[0044] Figure 3 This is a schematic diagram of the mixing chamber in Example 1;

[0045] Figure 4 This is a schematic diagram of the curved section in Example 1;

[0046] Figure 5 This is a schematic diagram of the eccentric reducer in Example 1;

[0047] Figure 6 This is a schematic diagram of the system structure in Example 2;

[0048] Figure 7 This is a schematic diagram of the cyclone separator in Example 2;

[0049] Figure 8 This is a schematic diagram of the system structure in Example 3;

[0050] The components include: 1. Rotary kiln; 2. Decomposition furnace; 3. Cooler; 4. Cyclone separator; 5. Integrated dust and nitrogen treatment device; 6. Mixing chamber; 7. Waste heat recovery furnace; 8. Control unit; 9. Chimney; 0. Bypass ash bin; 40. Separation bin; 41. Discharge bin; 42. Anti-backflow cone; 50. Bending section; 51. Eccentric reducer; 52. Guide plate; 61. First mixing duct; 62. Second mixing duct; 63. Guide vane; 81. Detection chamber; 82. Second gate; 83. Online laser detector; 84. Air inlet chamber; 85. First gate; 86. Linear electric cylinder; 87. Detection mechanism. Detailed Implementation

[0051] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings:

[0052] Example 1, as Figure 1-5 As shown, the bypass venting dust-nitrification-heat integrated treatment system includes a rotary kiln 1, a decomposition furnace 2 connected to the outlet of the rotary kiln 1, and a chimney 9. A bypass vent is provided at the connection between the rotary kiln 1 and the decomposition furnace 2. The system also includes a cooler 3, a cyclone separator 4, a dust-nitrification integrated treatment device 5, a mixing chamber 6, and a waste heat recovery furnace 7, which are connected in sequence between the bypass vent and the chimney 9.

[0053] The cyclone separator 4 includes a separation chamber 40 and a control unit 8 for controlling the flow rate of flue gas entering the separation chamber 40 from the cooler 3. The control unit 8 includes a detection mechanism 87 located in the flue gas treatment gas path formed by the cooler 3, the cyclone separator 4, and the integrated dust and nitrogen treatment device 5, an air inlet chamber 84 located on the air inlet of the separation chamber 40, a first gate 85 installed on the air inlet chamber 84 for controlling the opening of the air inlet entering the separation chamber 40, and a linear electric cylinder 86 for controlling the movement of the first gate.

[0054] The detection mechanism 87 includes a detection chamber 81 connected in parallel to the outlet of the separation chamber 40, a second gate 82 disposed on the detection chamber 81 for controlling the connection or isolation between the detection chamber 81 and the separation chamber 40, and an online laser detector 83 disposed on the detection chamber 81 for detecting the particulate concentration in the flue gas in the detection chamber 81 when the detection chamber 81 is isolated from the separation chamber 40.

[0055] The cyclone separator 4 also includes a discharge chamber 41 for discharging particulate matter, located at the lower end of the separation chamber 40; a conical anti-backflow cone 42 located inside the discharge chamber 41; and a connecting rod connecting the inner circumferential surface of the discharge chamber 41 and the outer circumferential surface of the anti-backflow cone 42. The upper end of the anti-backflow cone 42 is closed, and the lower end is open. A gap is formed between its outer wall and the inner wall of the discharge chamber 41 to allow particulate matter to descend and airflow to ascend. The distance between the outer circumferential surface of the anti-backflow cone 42 and the inner circumferential surface of the discharge chamber 41 decreases from top to bottom.

[0056] The mixing chamber 6 includes a first mixing duct 61 connected between the outlet of the integrated dust and nitrogen oxide treatment device 5 and the inlet of the waste heat recovery furnace 7, spiral guide vanes 63 disposed within the first mixing duct 61, and a second mixing duct 62 connected to the first mixing duct 61. The first mixing duct 61 introduces at least a portion of the hot air discharged from the waste heat recovery furnace 7 into the first mixing duct 61. The pitch of the guide vanes 63 increases from the outlet of the integrated dust and nitrogen oxide treatment device 5 towards the inlet of the waste heat recovery furnace 7. The guide vanes 63 are used to uniformly mix the gas discharged from the outlet of the integrated dust and nitrogen oxide treatment device 5 and the hot air discharged from the main treatment passage within the first mixing duct 61. The main treatment passage's processing equipment... The method is existing technology and will not be described in detail here. The front section of the guide vane 63 adopts a high-density, small-pitch design, which forces the fluid to quickly swirl and generate high-intensity shear force, rapidly breaking up the two airflow clusters with different temperatures. The rear section smoothly transitions to a low-density, large-pitch design, which, while inducing axial secondary flow to enhance turbulent mixing, effectively widens the flow channel to reduce frictional resistance along the flow path. Combined with the relatively small flow rate of the bypass high-temperature flue gas entering the mixing chamber tangentially, the tangential kinetic energy of the bypass flue gas and the guide vane 63 form a vortex core enhancement effect, driving the gas discharged from the outlet of the dust and nitrogen oxide integrated treatment device 5 to generate a long-path spiral motion. Under the premise of minimizing system pressure loss, it breaks the cold and hot stratification and achieves the homogenization of the flue gas temperature field.

[0057] An eccentric reducer 51 for placing particulate matter accumulation is connected to the air inlet of the integrated dust and nitrogen treatment device 5. The eccentric reducer 51 is connected between the cyclone separator 4 and the integrated dust and nitrogen treatment device 5. The upper side of the inner wall of the eccentric reducer 51 is horizontal and the lower side is inclined. The diameter of the eccentric reducer 51 increases from one end of the air inlet of the integrated dust and nitrogen treatment device 5 to the other end of the eccentric reducer 51. By adopting the eccentric reducer 51 with a flat top and inclined bottom, the stepped dust accumulation dead corner at the bottom of the traditional horizontal pipe is eliminated, ensuring the flow velocity threshold at the bottom of the pipe.

[0058] The curved section 50 of the connecting pipe between the cyclone separator 4 and the integrated dust and nitrogen treatment device 5 is equipped with an arc-shaped guide plate 52 that matches the curved section; this effectively rectifyes and eliminates the low-speed zone of the secondary eddy current induced by centrifugal force, which can reduce the natural settling rate of dust inside the pipe by 85%, and increase the stable operation cycle of the system to more than 60 days, and can achieve synchronous maintenance with the kiln system; this not only eliminates the production capacity loss caused by frequent shutdowns for dust cleaning, but also reduces the cost of manual maintenance.

[0059] Formulas for calculating the opening degree and inlet velocity:

[0060] The system air volume is determined by the power of the overall system fan, and can be considered a constant value when stable. However, by setting a first gate at the inlet of the cyclone separator, the inlet air velocity can be adjusted without changing the overall fan power. The relationship between the inlet air velocity and the gate opening is as follows:

[0061] Q: Flue gas volumetric flow rate entering the cyclone separator (m³) 3 / s);

[0062] Amax: Cross-sectional area of ​​the cyclone separator inlet when fully open (m²) 2 Amax is typically a rectangle, where Amax = H × W (height × width).

[0063] α: The percentage of opening of the first gate (%, with a value range of 0 < α < 1);

[0064] Cv: Flow coefficient (corrects for the fluid contraction effect caused by baffle throttling, usually taken as 0.95-0.98);

[0065] Therefore, the formulas for calculating the inlet air velocity Vin and the baffle opening α are:

[0066]

[0067] The inlet velocity v is inversely proportional to the opening α. By controlling α to vary between 0% and 80%, under the premise of constant flow rate Q, the tangential velocity of the airflow entering the cyclone can be forcibly increased by reducing the flow area. Thus, without increasing the energy consumption of the fan, the required high-speed flow field can be obtained by changing the physical structure.

[0068] The control method based on the above system includes the following steps:

[0069] a. Start the system and use a detection mechanism to detect the concentration and particle size distribution of particulate matter in the flue gas at the inlet or outlet of the cyclone separator 4, to obtain the corresponding staged removal efficiency η(d) under different opening degrees of the first gate 85 and flue gas velocities. p For the dataset, the hierarchical removal efficiency η(d) p The Theodore-De Paola empirical formula was used to estimate:

[0070]

[0071] Where, d p d represents the particle size of any particle; 50 The particle diameter at which the separation efficiency is 50% is a key indicator for measuring the precision of the separator, also known as d. 50 The smaller the size, the better the particle separation effect of cyclone separator 4; based on the classic Lapple model, the physical parameters are set as follows:

[0072] μ: Dynamic viscosity of flue gas (Pa·s), which is temperature-dependent;

[0073] W: Inlet width (m). Due to the obstruction by the baffle, the effective width here is Weff = W·α;

[0074] N e : The effective number of rotations within the cyclone separator 4 (usually 5-10 rotations);

[0075] V in The tangential air velocity at the air inlet (m / s) is obtained from the above formula;

[0076] ρ p Clinker particle density (kg / m³) 3 );

[0077] ρ g Smoke density (kg / m³) 3 );

[0078] Therefore, the formula for calculating the particle size distribution is:

[0079] ;

[0080] The formula for calculating the effective number of rotations of cyclone separator 4 is as follows:

[0081]

[0082] in

[0083] H: Height of the air inlet;

[0084] Lb: Length of the 4 cylindrical sections of the cyclone separator;

[0085] Lc: Length of the 4-conical section of the cyclone separator;

[0086] b. Based on the first gate opening of 85°, wind speed, and graded removal efficiency η(d) in the dataset. p The corresponding relationship is used to control the opening degree of the first gate at 85 degrees, thereby adjusting the graded removal efficiency η(d). p ).

[0087] When more particles need to be intercepted, reducing the baffle opening increases the airflow velocity at the inlet, thus increasing the centrifugal force on the particles squared. This, combined with the particle size calculation formula, d... 50 The size of particles will also decrease simultaneously, meaning that the removal efficiency of smaller particles can reach 50%, which means that the separation accuracy is improved and fine particles that could have escaped will also be captured.

[0088] Based on theoretical calculations and empirical estimations, the approximate correspondence between sliding door opening degree, wind speed, and particle removal efficiency is shown in the table below:

[0089]

[0090] Based on the table above, the optimal adjustment method for the inlet particle concentration and opening degree can be obtained as shown in the following table:

[0091]

[0092] Example 2, as Figure 6-7 As shown, the difference between this embodiment and embodiment one is only that: the detection chamber 81 has two inlets and outlets connected in parallel to the separation chamber 40. Connecting another detection chamber 81 in parallel to the inlet can verify that the opening degree of the first gate is controlled by the concentration difference between the inlet and outlet, which can improve the accuracy of the control timing and the precision of the opening degree.

[0093] Example 3, as Figure 8As shown, the bypass venting dust-nitrification-heat integrated treatment system includes a rotary kiln 1, a decomposition furnace 2 connected to the outlet of the rotary kiln 1, and a chimney 9. A bypass vent is provided at the connection between the rotary kiln 1 and the decomposition furnace 2. The system also includes a cooler 3, a cyclone separator 4, a dust-nitrification integrated treatment device 5, a mixing chamber 6, a waste heat recovery furnace 7, and a bypass ash silo 0 connected to the dust-nitrification integrated treatment device 5.

[0094] The cyclone separator 4 includes a separation chamber 40 and a control unit 8 for controlling the flow rate of flue gas entering the separation chamber 40 from the cooler 3. The control unit 8 includes a detection mechanism in the flue gas treatment gas path formed by the cooler 3, the cyclone separator 4, and the integrated dust and nitrogen treatment device 5, as well as an air inlet chamber 84 on the air inlet of the separation chamber 40 and a first gate 85 installed on the air inlet chamber 84 for controlling the opening degree of the air inlet entering the separation chamber 40.

[0095] The testing facility includes detectors for testing ash samples in bypass ash bin 0.

[0096] The cyclone separator 4 also includes a discharge chamber 41 for discharging particulate matter located at the lower end of the separation chamber 40, an anti-backflow cone 42 located inside the discharge chamber 41 and in the shape of a cone, and a connecting rod connecting the inner circumferential surface of the discharge chamber 41 and the outer circumferential surface of the anti-backflow cone 42. The upper end of the anti-backflow cone 42 is closed and the lower end is open. A gap is formed between its outer wall and the inner wall of the discharge chamber 41 for the particulate matter to descend and the airflow to ascend.

[0097] The distance between the outer circumferential surface of the anti-return cone 42 and the inner circumferential surface of the discharge chamber 41 decreases from top to bottom.

[0098] The mixing chamber 6 includes a first mixing duct 61 connecting the outlet of the integrated dust and nitrogen oxide treatment device 5 and the inlet of the waste heat recovery furnace 7, a spiral guide vane 63 disposed within the first mixing duct 61, and a second mixing duct 62 connected to the first mixing duct 61. The first mixing duct 61 introduces at least a portion of the hot air discharged from the waste heat recovery furnace 7 into the first mixing duct 61. The pitch of the guide vane 63 increases from the outlet of the integrated dust and nitrogen oxide treatment device 5 to the inlet of the waste heat recovery furnace 7. The guide vane 63 is used to uniformly mix the gas discharged from the outlet of the integrated dust and nitrogen oxide treatment device 5 and the hot air discharged from the main treatment passage within the first mixing duct 61. The guide vane 63 features a high-density, small-pitch design at its front end, which forces the fluid to quickly swirl and generate high-intensity shear force, rapidly breaking up two airflow clusters at different temperatures. The rear end smoothly transitions to a low-density, large-pitch design, which, while inducing axial secondary flow to enhance turbulent mixing, effectively widens the flow channel to reduce frictional resistance along the flow path. This, combined with the relatively small flow rate of the bypass high-temperature flue gas entering the mixing chamber tangentially, utilizes the tangential kinetic energy of the bypass flue gas to form a vortex core enhancement effect with the guide vane 63. This drives the gas discharged from the outlet of the integrated dust and nitrogen oxide treatment device 5 to generate a long-path spiral motion, breaking up the hot and cold stratification and achieving homogenization of the flue gas temperature field while minimizing system pressure loss.

[0099] An eccentric reducer 51 for placing particulate matter accumulation is connected to the air inlet of the integrated dust and nitrogen treatment device 5. The eccentric reducer 51 is connected between the cyclone separator 4 and the integrated dust and nitrogen treatment device 5. The upper side of the inner wall of the eccentric reducer 51 is horizontal and the lower side is inclined. The diameter of the eccentric reducer 51 increases from one end of the air inlet of the integrated dust and nitrogen treatment device 5 to the other end of the eccentric reducer 51. By adopting the eccentric reducer 51 with a flat top and inclined bottom, the stepped dust accumulation dead corner at the bottom of the traditional horizontal pipe is eliminated, ensuring the flow velocity threshold at the bottom of the pipe.

[0100] The curved sections of the connecting pipes of the cyclone separator 4 and the integrated dust and nitrogen treatment device 5 are equipped with arc-shaped guide plates 52 that match the curved sections; this effectively rectifyes and eliminates the low-speed zone of secondary eddies induced by centrifugal force, which can reduce the natural settling rate of dust inside the pipe by 85%, and extend the stable operation cycle of the system to more than 60 days, and can achieve synchronous maintenance with the kiln system; this not only eliminates the production capacity loss caused by frequent shutdowns for dust removal, but also reduces the cost of manual maintenance.

[0101] The control method based on the above system includes the following steps:

[0102] A. After the system has been running for a period of time, take out the ash sample from the bypass ash hopper and test the ash sample to establish the mapping relationship between the ash sample components and the separation efficiency;

[0103] B. The system periodically monitors the chloride ion concentration at the ash discharge port of the integrated dust and nitrogen oxide treatment unit; when the chloride concentration in the fine ash is too low, it indicates that the separation efficiency of cyclone separator 4 is insufficient, i.e., the classification particle size d is too low. 50 If the opening is too large, a large amount of low-chlorine-concentration coarse particles from raw and clinker will not be removed by the cyclone separator and will enter the ceramic filter, diluting the high-purity chlor-alkali ash. This not only increases the amount and cost of hazardous waste disposal but also exacerbates the physical wear of the ceramic filter tubes. In this case, the opening of the first gate can be reduced based on the recommended setting. By reducing the flow area, increasing the inlet air velocity, and enhancing the centrifugal force, the collection efficiency of coarse particles can be improved, reducing the escape of coarse particles and increasing the chlorine concentration of fine ash. When the chlorine concentration of fine ash meets the standard, but the chlor-alkali cycle of the system is not broken, excessively reducing the baffle opening in pursuit of higher separation efficiency will result in the grading particle size of cyclone separator 4 being too small, and even the capture of some coarser chlor-alkali salt crystals. This will cause too much high-chlorine-content chlor-alkali salt to return to the cement kiln with the coarse ash, causing the chlor-alkali components to re-accumulate in the kiln and failing to achieve the purpose of bypass venting to discharge harmful elements. Therefore, further analysis of the chlorine content in the cement kiln is needed. If an abnormal increase occurs, the kiln opening needs to be increased to ensure that fine chlor-alkali salts can escape smoothly from the cyclone and enter the back-end collection, thus being truly discharged from the firing system. If no abnormal increase occurs, the kiln opening should be kept unchanged.

[0104] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A bypass venting dust, nitrification, and heat integrated treatment system, characterized in that, The system includes a rotary kiln, a decomposition furnace connected to the kiln tail of the rotary kiln, and a chimney. A bypass vent is provided at the connection between the rotary kiln and the decomposition furnace. The decomposition furnace has a main exhaust port, which is connected to a main processing passage. The system also includes a cooler, a cyclone separator, an integrated dust and nitrogen oxide treatment device, a mixing chamber, and a waste heat recovery furnace, which are sequentially connected between the bypass vent and the chimney. The cyclone separator includes a separation chamber and a control unit for controlling the flow rate of flue gas entering the separation chamber from the cooler. The control unit includes a detection mechanism in the flue gas treatment gas path formed by the cooler, the cyclone separator, and the integrated dust and nitrification treatment device, an air inlet chamber on the air inlet of the separation chamber, and a first gate installed on the air inlet chamber for controlling the opening degree of the air inlet entering the separation chamber. The cyclone separator also includes a discharge chamber for discharging particulate matter located at the lower end of the separation chamber, and an anti-backflow cone located inside the discharge chamber in the shape of a cone. The upper end of the anti-backflow cone is closed and the lower end is open. A gap is formed between its outer wall and the inner wall of the discharge chamber to allow particulate matter to descend and airflow to ascend. The distance between the outer circumferential surface of the anti-return cone and the inner circumferential surface of the discharge chamber decreases from top to bottom; The mixing chamber includes a first mixing duct connected to the main processing passage, a second mixing duct connected between the outlet of the integrated dust and nitrogen oxide treatment device and the inlet of the waste heat recovery furnace, and spiral guide vanes disposed in the first mixing duct. The pitch of the guide vanes increases from the outlet of the integrated dust and nitrogen oxide treatment device to the inlet of the waste heat recovery furnace.

2. The bypass venting dust, nitrogen, and heat integrated treatment system according to claim 1, characterized in that: The detection mechanism includes a detection chamber connected in parallel to the air outlet of the separation chamber or a detection chamber connected in parallel to the air inlet and air outlet of the separation chamber, a second gate disposed on the detection chamber for controlling the connection or isolation between the detection chamber and the separation chamber, and an online laser detector disposed on the detection chamber for detecting the particulate concentration in the flue gas inside the detection chamber when the detection chamber is isolated from the separation chamber.

3. The bypass venting dust, nitrogen, and heat integrated treatment system according to claim 1, characterized in that: The air inlet of the integrated dust and nitrogen oxide treatment device is connected to an eccentric reducer for preventing particulate matter accumulation. The eccentric reducer is connected between the cyclone separator and the integrated dust and nitrogen oxide treatment device. The upper side of the inner wall of the eccentric reducer is horizontal and the lower side is inclined. The diameter of the eccentric reducer increases from one end of the air inlet of the integrated dust and nitrogen oxide treatment device to the other end of the eccentric reducer.

4. The bypass venting dust, nitrogen, and heat integrated treatment system according to claim 1, characterized in that: The curved section of the connecting pipe between the cyclone separator and the integrated dust and nitrification treatment device is equipped with an arc-shaped guide plate that matches the curved section.

5. The bypass venting dust, nitrogen, and heat integrated treatment system according to claim 1, characterized in that: The system also includes a bypass ash hopper connected to the integrated dust and nitrification treatment device.

6. A control method based on the system according to any one of claims 1-4, characterized in that, It includes the following steps: a. Start the system and use a detection mechanism to detect the concentration and particle size distribution of particulate matter in the flue gas at the inlet or outlet of the cyclone separator, and obtain the corresponding staged removal efficiency η(d) under different opening degrees of the first gate and flue gas velocities. p For the dataset, the hierarchical removal efficiency η(d) p The Theodore-De Paola empirical formula was used to estimate: ； Where, d p d represents the particle size of any particle; 50 The particle diameter at which the separation efficiency is 50% is a key indicator for measuring the precision of the separator, also known as d. 50 The smaller the value, the better the particle separation effect of the cyclone separator; based on the classic Lapple model, the physical parameters are set as follows: μ: Dynamic viscosity of flue gas (Pa·s), which is temperature-dependent; W: Inlet width (m). Due to the obstruction by the baffle, the effective width here is Weff = W·α; N e The effective number of rotations within the cyclone separator is 5-10. V in The tangential air velocity at the air inlet (m / s) is obtained from the above formula; ρ p Clinker particle density (kg / m³) 3 ); ρ g Smoke density (kg / m³) 3 ); Therefore, the formula for calculating the particle size distribution is: ； The formula for calculating the effective number of rotations of a cyclone separator is: ； in H: Height of the air inlet; L b : The length of the cylindrical section of the cyclone separator; L c : The length of the conical section of the cyclone separator; b. Based on the first gate opening, wind speed, and graded removal efficiency η(d) in the dataset p The corresponding relationship is used to control the opening of the first gate, thereby adjusting the graded removal efficiency η(d). p ).

7. A control method based on the system of claim 5, characterized in that, It includes the following steps: A. After the system has been running for a period of time, take out the ash sample from the bypass ash hopper and test the ash sample to establish the mapping relationship between the ash sample components and the separation efficiency; B. The system periodically monitors the chloride ion concentration at the ash discharge port of the integrated dust and nitrogen oxide treatment device. When the chloride concentration in the fine ash is too low, the opening of the first gate is reduced. When the chloride concentration in the fine ash meets the standard, but the chlor-alkali cycle of the system is not broken, further analysis is needed in conjunction with the chloride content in the cement kiln. If an abnormal increase occurs, the opening needs to be increased. If no abnormal increase occurs, the opening remains unchanged.

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