Deep self-denitration self-adaptive intelligent pre-decomposition kiln tail system

Abstract

The invention relates to the technical field of pre-decomposition of a cement sintering system, and discloses a deep self-denitration self-adaptive intelligent pre-decomposition kiln tail system which comprises a decomposing furnace, a material distributing valve, a tertiary air pipe, a pulverized coal conveying pipeline, a coal injection nozzle, a material distributing device, a crust cleaning device, a temperature measuring device and a pressure measuring device. The system comprises a kiln tail smoke chamber, a decomposing furnace, a secondary cyclone, a reduction furnace, a crust cleaning device, a pulverized coal conveying pipeline control valve, a high-temperature electric gate valve, a tertiary air inlet, a raw material feeding point, a fuel feeding point, a high-precision gas analyzer and an intelligent control system, and a blanking pipe of the secondary cyclone divides the raw material into two paths through a material distribution valve, and the two paths of raw material are respectively fed into the decomposing furnace and the reducing furnace. According to the invention, accurate adjustment can be realized, manual operation errors can be prevented, the labor intensity of workers can be greatly reduced, and intelligent automatic control of the self-denitration function of the decomposing furnace and maximum development of the system capability can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of pre-decomposition of cement burning systems, and in particular to a deep self-denitrification self-adaptive intelligent pre-decomposition kiln tail system. Background Art

[0002] As an energy resource-based high-temperature decomposition and high-temperature calcination industry, the cement industry has a large scale of nitrogen oxide emissions, and the task of emission reduction is very arduous.

[0003] At present, the main sources of nitrogen oxides in the cement industry are basically divided into the following three ways:

[0004] 1. Fuel-type NOx, which is converted from fuel N, fluctuates with the change of raw material composition and is not easy to control in process operation and system transformation. Fuel-type NOx is mainly generated when fuel is burned in rotary kilns and decomposition furnaces;

[0005] 2. Thermal NOx, mainly produced in the high temperature area of ​​the rotary kiln. When the temperature is greater than 1500°C, as the temperature rises, the formation of NOx increases exponentially. Thermal NOx is the main source of NOx in cement production;

[0006] 3. Rapid NOx: When hydrocarbon fuels burn in an oxygen-rich environment, CH, CH2 and other groups react quickly with N2 in the air. It has weak dependence on temperature and accounts for less than 5% of the total NOx.

[0007] As can be seen from the above, the main sources of nitrogen oxides in the cement industry are fuel-based and thermal-based. The fuel-based ones are mainly produced by fuel combustion in the decomposition furnace and rotary kiln, and the thermal-based ones are mainly produced in the high-temperature area of ​​the rotary kiln. The following solutions are currently used to control NOx content in ordinary cement kiln systems:

[0008] 1. Low NOx combustion control technology, such as air staging technology, fuel staging technology, low NOx burner, etc. From the perspective of usage, fuel staging technology is most suitable for cement industry. It mainly relies on the reducing agent produced by coal powder in an oxygen-deficient environment to reduce NOx to harmless gases such as N2. However, it is limited by the existing decomposition furnace structure, and the reduction time is short, resulting in low denitrification efficiency;

[0009] 2. Flue gas purification technology, mainly SNCR and / or SCR technology, has high denitrification efficiency, but high investment and operating costs. It is difficult to achieve ultra-low NOx emissions with SNCR technology alone, and it will lead to an increase in ammonia consumption; SCR technology alone can achieve ultra-low NOx emissions, but the catalyst consumption is large and the cost is high.

[0010] Taking into account the use cost and effect, the use of only one of the solutions cannot meet the ultra-low emission index requirements of nitrogen oxides. The deep self-denitrification decomposition furnace using fuel grading technology plus SNCR technology can achieve ultra-low emission requirements while significantly reducing the use of ammonia water. However, the O2 content in the smoke chamber, the fuel distribution ratio, the raw material distribution ratio, the tertiary air inlet position and valve opening, the decomposition furnace cone temperature and pressure control value, etc. have a great influence on the initial NOx concentration at the decomposition furnace outlet. The raw fuel and production conditions are complex and changeable, and good control effects cannot be achieved by on-site production exploration and manual adjustment. This patent aims to propose a deep self-denitrification adaptive intelligent pre-decomposition kiln tail system to meet the requirements that the system automatically finds the optimal data of fuel distribution ratio, raw material distribution ratio, tertiary air valve opening, and decomposition furnace cone temperature and pressure control value without or with little manual intervention, so as to achieve the best match between ammonia water consumption and production, which is of great significance to the automated control of nitrogen oxide emission reduction in the cement industry. Summary of the invention

[0011] 1. Technical issues to be resolved

[0012] In view of the deficiencies in the prior art, the present invention provides a deep self-denitrification adaptive intelligent pre-decomposition kiln tail system, which solves the problem that the deep self-denitrification function of the existing preheater decomposition furnace cannot achieve the expected effect.

[0013] (II) Technical solution

[0014] To achieve the above object, the present invention provides the following technical solutions:

[0015] A deep self-denitrification adaptive intelligent pre-decomposition kiln tail system, comprising a decomposition furnace, a material distribution valve, a tertiary air duct, a coal powder conveying pipeline, a coal nozzle, a distributor, a descaling device, a temperature measuring device and a pressure measuring device, and also comprising a secondary cyclone, a reduction furnace, a descaling device, a coal powder conveying pipeline control valve, a high-temperature electric gate valve, a tertiary air inlet, a raw material feeding point, a fuel feeding point, a high-precision gas analyzer and an intelligent control system. The reduction furnace is located between the kiln tail smoke chamber and the decomposition furnace, and the feed pipe of the secondary cyclone divides the raw material into two paths through the material distribution valve, which are respectively fed into the decomposition furnace and the reduction furnace, and correspond to the raw material feeding point 1 and the raw material feeding point 2, the raw material feeding point 1 is located above the tertiary air duct inlet, the raw material feeding point 2 is located at the lower part of the reduction furnace, the high-precision gas analyzer is located at the decomposition furnace outlet and the middle of the kiln tail smoke chamber, the tertiary air duct inlet is located at the junction of the reduction furnace and the decomposition furnace; the high The high-temperature electric gate valve is located on the main line of the tertiary air duct; the decomposition furnace and the reduction furnace are both provided with fuel feeding points, which are respectively located around the fuel feeding surface 1 and the fuel feeding surface 2 which are perpendicular to the center line of the decomposition furnace, the fuel feeding surface 1 is located between the furnace inlet of the tertiary air duct and the raw meal feeding point 1, and the fuel feeding surface 2 is located below the raw meal feeding point 2; the descaling device is located between the raw meal feeding point 2 and the fuel feeding surface 2, slightly higher than the height of the fuel feeding point 2; 4 sets of the temperature measuring device and the pressure measuring device are arranged, which are located around the cross section about 1m above the fuel feeding point 2 and are evenly distributed along the circumference; the gas analyzer, the material distribution valve, the high-temperature electric gate valve, the coal powder conveying pipeline control valve, and the temperature measuring device are all connected to the intelligent control system; there is only kiln gas from the rotary kiln inside the reduction furnace, and this area is an oxygen-poor combustion zone; the decomposition furnace has both flue gas from the reduction furnace and tertiary air from the kiln head, and this area is an oxygen-rich combustion zone.

[0016] Furthermore, the system obtains data such as NOx concentration and O2 concentration in the smoke chamber, temperature of the decomposition furnace and reduction zone, pressure of the reduction furnace, NOx concentration and O2 concentration at the outlet of the decomposition furnace, and then adjusts the pulverized coal injection position in the reduction zone, the raw meal feeding point position and the tertiary air valve opening parameters through the central control system.

[0017] On the basis of the above, the gas analyzer transmits the gas composition analysis results of the decomposition furnace outlet and the kiln tail smoke chamber to the intelligent control system in real time, and the temperature measuring device and the pressure measuring device transmit the reduction furnace cone temperature and pressure to the intelligent control system in real time. The intelligent control system issues adjustment instructions to the dividing valve, high-temperature electric gate valve, and coal powder conveying pipeline control valve according to the set NOx concentration value, O2 content in the kiln tail smoke chamber, and the reduction furnace cone temperature and pressure change rate. The intelligent control system continuously records production data and establishes a database to continuously improve the accuracy of judging the working condition of this system. The intelligent control system is also connected to the production data of the firing system to judge whether the working condition of the firing system has changed due to the adjustment of this system.

[0018] As a further solution of the present invention, the NOx concentration at the outlet of the decomposition furnace is theoretically calculated by the system according to a mathematical model. The system compares the theoretically calculated value with the actual measured value and performs iterative analysis and calculation to infer the relevant calculation coefficients of the actual working conditions on site, thereby forming a mathematical model that adapts to different working conditions.

[0019] Furthermore, the high-temperature electric gate valve adjusts the air volume entering the furnace through the tertiary air duct according to the opening instruction issued by the intelligent control system.

[0020] On the basis of the above, the distribution valve distributes the material in the secondary cyclone discharge pipe to the raw material feeding point 1 and the raw material feeding point 2 according to the distribution ratio issued by the intelligent control system to adjust the temperature in the reduction furnace.

[0021] As a further solution of the present invention, the raw meal feeding point 1 and the raw meal feeding point 2 are both designed with distributors, and the raw meal feeding point 1 and the raw meal feeding point 2 are each designed with multiple branch feeding points at the same feeding height.

[0022] Furthermore, the pulverized coal conveying pipeline control valve adjusts the valve opening of each branch pipeline according to the opening instruction issued by the intelligent control system, thereby controlling the coal feeding ratio of each fuel feeding point on the fuel feeding surface 1 and the fuel feeding surface 2.

[0023] On the basis of the foregoing, the crust removing device starts the program according to the instruction issued by the intelligent control system.

[0024] As a further solution of the present invention, the tertiary air enters the decomposition furnace at a fixed height without the need for upper and lower air division.

[0025] Furthermore, each fuel feeding point is provided with a coal nozzle, and the feeding points and the coal nozzles on the same fuel feeding surface 1 and the fuel feeding surface 2 are symmetrically distributed along the circumference.

[0026] (III) Beneficial effects

[0027] Compared with the prior art, the present invention provides a deep self-denitrification adaptive intelligent pre-decomposition kiln tail system, which has the following beneficial effects:

[0028] 1. In the present invention, the gas residence time in the reduction furnace is long, and the fuel-type and thermal-type NOx generated in the rotary kiln can be completely removed in the reduction furnace through its strong reducing atmosphere, and the generation of some fuel-type NOx in the decomposition furnace can be suppressed. The NOx concentration at the outlet of the decomposition furnace can be controlled to be lower than 250mg / Nm3 by adjustment, thereby reducing the subsequent ammonia consumption; and the intelligent control system analyzes the production data uploaded by the gas analyzer, the temperature measuring device and the pressure measuring device in real time, and automatically issues the operating parameters of the material distribution valve, the high-temperature electric gate valve, the coal powder conveying pipeline control valve, and the descaling device, and adjusts the NOx value at the outlet of the decomposition furnace by controlling the opening of the fuel, raw material, and the tertiary air valve. The descaling device is controlled to start and stop to prevent and clean the possible crusting in the local high-temperature area of ​​the cone of the reduction furnace, and finally realizes the intelligent automatic adjustment of the deep self-denitrification function of the preheater decomposition furnace system.

[0029] 2. The present invention can solve the problem that the deep self-denitrification function of the existing preheater decomposition furnace cannot achieve the expected effect. The system is simple and does not require manual intervention. Through data analysis and in conjunction with subsequent denitrification technologies such as SNCR, ultra-low NOx emissions can be achieved with a small amount of ammonia water. Compared with the existing self-denitrification decomposition furnace technology, the tertiary air of this system enters the furnace at a fixed position and does not require air classification technology. The intelligent control system adjusts the raw material, pulverized coal, and tertiary air according to feedback data to control the reduction furnace to form a strong reducing atmosphere. The longer reduction furnace path increases the gas reaction time, so that the NOx formed by the rotary kiln can be completely removed within this range. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic elevational diagram of a preparation method of a deep self-denitrification adaptive intelligent pre-decomposition kiln tail system in the present invention;

[0031] Figure 2 A schematic diagram of the layout of the coal powder conveying pipeline in a method for preparing a deep self-denitrification adaptive intelligent pre-decomposition kiln tail system in the present invention;

[0032] Figure 3 The present invention is a program control flow chart of a method for preparing a deep self-denitrification adaptive intelligent pre-decomposition kiln tail system.

[0033] In the figure: 3. Reduction furnace; 4. Decomposition furnace; 5. High-temperature electric gate valve; 6. Temperature measuring device; 7. Descaling device; 8. Distribution valve; 9. High-precision gas analyzer; 10. Tertiary air duct; 11. Pressure measuring device. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] Reference Figure 1-Figure 3 A deep self-denitrification adaptive intelligent pre-decomposition kiln tail system, including a decomposition furnace 4, a material distribution valve 8, a tertiary air duct 10, a coal powder conveying pipeline, a coal nozzle, a distributor, a temperature measuring device 6 and a pressure measuring device 11, and also includes a secondary cyclone, a reduction furnace 3, a descaling device 7, a coal powder conveying pipeline control valve, a high-temperature electric gate valve 5, a tertiary air inlet, a raw material feeding point, a fuel feeding point, a high-precision gas analyzer 9 and an intelligent control system. The reduction furnace 3 is located at the kiln tail smoke The feed pipe of the secondary cyclone is between the chamber and the decomposition furnace 4. The raw material is divided into two paths by the feed valve 8, and is fed into the decomposition furnace 4 and the reduction furnace 3 respectively, and corresponds to the raw material feeding point 1 and the raw material feeding point 2. The raw material feeding point 1 is located above the furnace inlet of the tertiary air duct 10, and the raw material feeding point 2 is located at the lower part of the reduction furnace 3. The high-precision gas analyzer 9 is located at the outlet of the decomposition furnace 4 and the middle of the kiln tail smoke chamber. The furnace inlet of the tertiary air duct 10 is located at the junction of the reduction furnace 3 and the decomposition furnace 4. ; The high-temperature electric gate valve 5 is located on the main line of the tertiary air duct 10; the decomposition furnace 4 and the reduction furnace 3 are both provided with fuel feeding points, which are respectively located around the fuel feeding surface 1 and the fuel feeding surface 2 which are perpendicular to the center line of the decomposition furnace 4, the fuel feeding surface 1 is located between the furnace inlet of the tertiary air duct 10 and the raw material feeding point 1, and the fuel feeding surface 2 is located below the raw material feeding point 2; the descaling device 7 is located between the raw material feeding point 2 and the fuel feeding surface 2, slightly higher than the height of the fuel feeding point 2; 4 sets of temperature measuring devices 6 and pressure measuring devices 11 are arranged, which are located around the cross section about 1m above the fuel feeding point 2 and are evenly distributed along the circumference; the gas analyzer, the dividing valve 8, the high-temperature electric gate valve 5, the coal powder conveying pipeline control valve, and the temperature measuring device 6 are all connected to the intelligent control system; there is only kiln gas from the rotary kiln inside the reduction furnace 3, and this area is an oxygen-poor combustion zone; the decomposition furnace 4 has both flue gas from the reduction furnace 3 and tertiary air from the kiln head, and this area is an oxygen-rich combustion zone.

[0037] It should be noted that the system obtains data such as NOx concentration and O2 concentration in the smoke chamber, temperature of the decomposition furnace 4 and the reduction zone, pressure of the reduction furnace 3, NOx concentration and O2 concentration at the outlet of the decomposition furnace 4, and then adjusts the coal powder injection position in the reduction zone, the position of the raw material feeding point and the opening parameters of the tertiary air valve through the central control system, thereby realizing the control of the NOx concentration at the outlet of the decomposition furnace 4. The gas analyzer transmits the gas composition analysis results of the outlet of the decomposition furnace 4 and the smoke chamber at the tail of the kiln to the intelligent control system in real time. The temperature measuring device 6 and the pressure measuring device 11 transmit the cone temperature and pressure of the reduction furnace 3 to the intelligent control system in real time. The intelligent control system adjusts the NOx concentration according to the set NOx concentration value, the O2 content in the smoke chamber at the tail of the kiln, and the cone temperature and pressure of the reduction furnace 3. The rate of change issues adjustment instructions to the material distribution valve 8, the high-temperature electric gate valve 5, and the coal powder conveying pipeline control valve. The intelligent control system continuously records production data and establishes a database to continuously improve the accuracy of the judgment of the working condition of the system. The intelligent control system is also connected with the production data of the burning system to determine whether the working condition of the burning system has changed due to the adjustment of the system. The NOx concentration at the outlet of the decomposition furnace 4 is theoretically calculated by the system according to the following mathematical model. The system can compare the theoretically calculated value with the actual measured value for iterative analysis and calculation, and reversely deduce the relevant calculation coefficients of the actual working condition on site, forming a mathematical model that adapts to different working conditions, thereby improving the system adjustment accuracy and realizing the diversity of adjustment means. The mathematical model is as follows:

[0038]

[0039] F: NOx concentration at the outlet of decomposition furnace 4, mg / Nm3, dry basis @10% O2

[0040] m: NOx concentration in smoke chamber, mg / Nm3, dry basis @10% O2

[0041] x1: O2 concentration in smoke chamber, %, x1>0.5

[0042] n1: impact factor, 0 to 1

[0043] T: Reduction zone temperature, °C, T<1000°C

[0044] n2: Impact factor, 1 to 5

[0045] t: Reduction zone reaction time, s

[0046] x2: O2 concentration at the outlet of decomposition furnace 4, %, x2>0.5

[0047] n3: Impact factor, 0 to 1

[0048] In particular, the high-temperature electric gate valve 5 adjusts the air volume of the tertiary air duct 10 according to the opening instruction issued by the intelligent control system, and the distribution valve 8 distributes the materials in the secondary cyclone discharge pipe to the raw material feeding point 1 and the raw material feeding point 2 according to the distribution ratio issued by the intelligent control system to adjust the temperature in the reduction furnace 3. The raw material feeding point 1 and the raw material feeding point 2 are both designed with distributors. The raw material feeding point 1 and the raw material feeding point 2 are each designed with multiple branch feeding points at the same feeding height. The pulverized coal conveying pipeline control valve adjusts the opening and closing of the pulverized coal conveying pipeline according to the opening and closing of the pulverized coal conveying pipeline. The degree instruction adjusts the valve opening of each branch pipeline, so as to control the coal feeding ratio of each fuel feeding point on the fuel feeding surface 1 and the fuel feeding surface 2. The crust cleaning device 7 starts the program according to the instruction issued by the intelligent control system, so as to prevent the crusting and clean the initial crust in time to ensure the normal operation of the system. The tertiary air enters the decomposition furnace 4 at a fixed height, and there is no need to divide the air up and down. Each fuel feeding point is provided with a coal nozzle. The feeding points and coal nozzles on the same fuel feeding surface 1 and the fuel feeding surface 2 are symmetrically distributed along the circumference to obtain a uniform temperature field.

[0049] Example 2

[0050] Reference Figure 1-Figure 3A deep self-denitrification adaptive intelligent pre-decomposition kiln tail system, including a reduction furnace 3, a decomposition furnace 4, a smoke chamber and a gas analyzer for the decomposition furnace 4, a material distribution valve 8, a tertiary air duct 10, a high-temperature electric gate valve 5, a coal powder conveying pipeline, a coal powder conveying pipeline control valve, a coal nozzle, a distributor, a descaling device 7, a temperature measuring device 6, a pressure measuring device 11 and an intelligent control system; the gas analyzer for the decomposition furnace 4 is installed at the outlet of the decomposition furnace 4, and the gas analyzer for the smoke chamber is located in the middle of the smoke chamber; the bottom of the reduction furnace 3 is connected to the smoke chamber, and the outlet is connected to the bottom of the decomposition furnace 4; the tertiary air duct 10 is at the bottom of the decomposition furnace 4 The tertiary air is fed into the decomposition furnace 4, and a high-temperature electric gate valve 5 is provided on the tertiary air duct 10; a dividing valve 8 is provided on the discharge pipe of the secondary cyclone to divide the material into two routes, the upper route is fed into the upper part of the tertiary air duct 10 through the raw material feeding point 1 (WL1), and the lower route is fed into the cone of the reduction furnace 3 through the raw material feeding point 2 (WL2); the pulverized coal conveying pipeline is divided into: the main coal pipe 1-ZMG1, ZMG1 is divided into two routes, one route goes between WL1 and the entrance of the tertiary air duct 10, code ZMG1.1, and the other route goes to the cone of the reduction furnace 3 and below WL2, code ZMG1.2; the main coal pipe 2-ZMG2, ZMG2 is divided into 2 routes, 1 route goes between WL1 and the entrance of the tertiary air duct 10, code-named ZMG2.1, and 1 route goes to the cone of the reduction furnace 3 and below WL2, code-named ZMG2.2; among them, ZMG1.1, ZMG1.2, ZMG2.1, and ZMG2.2 can be divided into 2 routes to enter the decomposition furnace 4 and the reduction furnace 3 at their respective coal feeding heights, and can be divided into more branches according to actual needs, as a separate embodiment, no further introduction is made here; a descaling device 7 and a temperature measuring device are set between the coal feeding height of ZMG1.2 and ZMG2.2 and WL2 6 and a pressure measuring device 11; pulverized coal conveying pipeline control valves (F1, F2, F1.1, F1.2, F2.1, F2.2) are arranged on the pulverized coal conveying pipeline and its branches, and a coal nozzle is arranged at the end entering the furnace; distributors are arranged at WL1 and WL2; the smoke chamber, the decomposition furnace 4 gas analyzer, the temperature measuring device 6, the pressure measuring device 11, the distribution valve 8, the high-temperature electric gate valve 5, and the descaling device 7 are connected to the intelligent control system, and the intelligent control system performs unified adjustment according to the NOx concentration value at the outlet of the decomposition furnace 4 and the cone temperature of the reduction furnace 3 provided by the temperature measuring device 6.

[0051] As an embodiment of the present invention, we assume a production condition that may be encountered in practice, and explain the adjustment method of the system based on this condition:

[0052] The intelligent control system sets the numerical parameter range, and the NOx concentration at the outlet of decomposition furnace 4 is set to 250mg / Nm 3, the setting range of the cone temperature of the reduction furnace 3 is 850℃-950℃; when the temperature measuring device 6 feeds back that the cone temperature of the reduction furnace 3 is outside the set temperature range, the intelligent control system will try multiple adjustment schemes according to the set ideas, control the pulverized coal pipeline control valve to adjust the coal feeding amount of ZMG1.2 and ZMG2.2, and control the distribution valve 8 to adjust the feeding amount of WL2. The feeding amount ratio of WL2 in this system shall not exceed 75% of the total feeding amount of the system, so that the temperature of the reduction furnace 3 returns to the set range. During the trial process, the intelligent control system will continue to record production data. Because the intelligent control system is connected to the production data of the burning system, it will adopt the best adjustment method according to the indicators of the burning system and record the adjustment method under this working condition. The opening of the distribution valve 8 should be adjusted step by step with a gradient of 2%, and the coal feeding amount should be adjusted at a ratio of 2%; when the NOx concentration at the outlet of the decomposition furnace 4 is greater than the set value, the intelligent control system will continue to record the production data. The control system increases the ventilation volume of the tertiary air duct 10 through the high-temperature electric gate valve 5 to reduce the ventilation in the kiln, and at the same time increases the coal feeding amount of ZMG1.2 and ZMG2.2 and the feeding amount of WL2, and correspondingly reduces the coal feeding amount of ZMG1.1 and ZMG2.1 and the feeding amount of WL1 to increase the reducing atmosphere of the reduction furnace 3. The intelligent control system will also try a variety of adjustment schemes to make the sintering system in the best state. After the adjustment, if the temperature of the reduction furnace 3 is out of the temperature control range, the temperature adjustment steps will be repeated until the monitoring data of the intelligent control system returns to normal. The opening of the high-temperature electric gate valve 5 of the tertiary air duct 10 is adjusted with a gradient of 2%; the intelligent control system will use the pressure data change rate fed back by the pressure measuring device 11. When the pressure has an increasing trend, the command issued will start the skin removal system to prevent the formation of skin and clean the initial skin in time to ensure the normal operation of the system. The intelligent control system continuously records production data, establishes a database, and continuously optimizes the mathematical model to continuously improve the accuracy of judging the system working conditions and reduce misjudgment.

[0053] The present invention can solve the problem that the deep self-denitrification function of the existing preheater decomposition furnace 4 cannot achieve the expected effect. The system is simple and does not require human intervention. Accurate adjustment can be achieved through data analysis, which prevents human operating errors and greatly reduces manual labor intensity. The intelligent automatic control of the self-denitrification function of the decomposition furnace 4 and the maximum exertion of the system capacity can be achieved. In conjunction with subsequent denitrification technologies such as SNCR, the demand for ultra-low NOx emissions can be achieved with a small amount of ammonia water. Compared with the existing self-denitrification decomposition furnace 4 technology, the tertiary air of this system is fixed at the furnace, and no air classification technology is required. The intelligent control system adjusts the raw material, coal powder and tertiary air according to the feedback data to control the reduction furnace 3 to form a strong reducing atmosphere. The longer reduction furnace 3 path increases the gas reaction time, so that the NOx formed by the rotary kiln can be completely removed within this range.

[0054] Finally, it should be noted that the above embodiment is only an implementable technical case of the present invention, and does not limit it. Although the present invention has been described in detail with reference to the aforementioned embodiment, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A deep self-denitrification adaptive intelligent pre-decomposition kiln tail system, comprising a decomposition furnace (4), a material distribution valve (8), a tertiary air duct (10), a coal powder conveying pipeline, a coal injection nozzle, a distributor, a temperature measuring device (6) and a pressure measuring device (11), characterized in that: The invention also comprises a secondary cyclone, a reduction furnace (3), a descaling device (7), a coal powder conveying pipeline control valve, a high-temperature electric gate valve (5), a tertiary air inlet, a raw material feeding point, a fuel feeding point, a high-precision gas analyzer (9) and an intelligent control system. The reduction furnace (3) is located between the kiln tail smoke chamber and the decomposition furnace (4). The feed pipe of the secondary cyclone divides the raw material into two paths through a feed dividing valve (8), which are respectively fed into the decomposition furnace (4) and the reduction furnace (3). A material point 1 and a raw material feeding point 2, wherein the raw material feeding point 1 is located above the furnace inlet of the tertiary air duct (10), the raw material feeding point 2 is located at the lower part of the reduction furnace (3), the high-precision gas analyzer (9) is located at the outlet of the decomposition furnace (4) and the middle of the kiln tail smoke chamber, the furnace inlet of the tertiary air duct (10) is located at the junction of the reduction furnace (3) and the decomposition furnace (4); the high-temperature electric gate valve (5) is located on the main pipe of the tertiary air duct (10); the decomposition furnace (4) and the The reduction furnace (3) is provided with fuel feeding points, which are respectively located around the fuel feeding surface 1 and the fuel feeding surface 2 which are perpendicular to the center line of the decomposition furnace (4); the fuel feeding surface 1 is located between the furnace inlet of the tertiary air duct (10) and the raw material feeding point 1, and the fuel feeding surface 2 is located below the raw material feeding point 2; the descaling device (7) is located between the raw material feeding point 2 and the fuel feeding surface 2, slightly higher than the height of the fuel feeding point 2; the temperature measuring device (6) and the pressure measuring device (11) are arranged Four sets are arranged, located around the cross section about 1 m above the fuel feeding point 2 and evenly distributed along the circumference; the gas analyzer, the material distribution valve (8), the high-temperature electric gate valve (5), the coal powder conveying pipeline control valve, and the temperature measuring device (6) are all connected to the intelligent control system; the reduction furnace (3) has only kiln gas from the rotary kiln, and this area is an oxygen-poor combustion area; the decomposition furnace (4) has both smoke from the reduction furnace (3) and tertiary air from the kiln head, and this area is an oxygen-rich combustion area.

2. A deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1, characterized in that: The system obtains data such as NOx concentration and O2 concentration in the smoke chamber, temperature of the decomposition furnace (4) and the reduction zone, pressure of the reduction furnace (3), NOx concentration and O2 concentration at the outlet of the decomposition furnace (4), and then adjusts the coal powder injection position in the reduction zone, the position of the raw material feeding point and the opening parameters of the tertiary air valve through the central control system.

3. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The gas analyzer transmits the analysis results of the gas composition at the outlet of the decomposition furnace (4) and the kiln tail smoke chamber to the intelligent control system in real time. The temperature measuring device (6) and the pressure measuring device (11) transmit the cone temperature and pressure of the reduction furnace (3) to the intelligent control system in real time. The intelligent control system issues adjustment instructions to the material distribution valve (8), the high-temperature electric gate valve (5), and the coal powder conveying pipeline control valve according to the set NOx concentration value, the O2 content in the kiln tail smoke chamber, and the cone temperature and pressure change rate of the reduction furnace (3). The intelligent control system continuously records production data and establishes a database to continuously improve the accuracy of judging the working condition of the system. The intelligent control system is also connected with the production data of the firing system to judge whether the working condition of the firing system has changed due to the adjustment of the system.

4. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The NOx concentration at the outlet of the decomposition furnace (4) is theoretically estimated by the system according to a mathematical model. The system compares the theoretically estimated value with the actual measured value and performs iterative analysis and calculation to infer the relevant calculation coefficients of the actual working conditions on site, thereby forming a mathematical model suitable for different working conditions.

5. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The high-temperature electric gate valve (5) adjusts the amount of air entering the furnace through the tertiary air duct (10) according to an opening instruction issued by the intelligent control system.

6. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The distribution valve (8) distributes the material in the secondary cyclone discharge pipe to the raw material feeding point 1 and the raw material feeding point 2 according to the distribution ratio issued by the intelligent control system, so as to adjust the temperature in the reduction furnace (3).

7. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The raw meal feeding point 1 and the raw meal feeding point 2 are both designed with distributors, and the raw meal feeding point 1 and the raw meal feeding point 2 are each designed with multiple branch feeding points at the same feeding height.

8. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The pulverized coal conveying pipeline control valve adjusts the valve opening of each branch pipeline according to the opening instruction issued by the intelligent control system, thereby controlling the coal feeding ratio of each fuel feeding point on the fuel feeding surface 1 and the fuel feeding surface 2.

9. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 1 is characterized in that: The skin removal device (7) starts a program according to the instructions issued by the intelligent control system.

10. The deep self-denitrification adaptive intelligent pre-decomposition kiln tail system according to claim 6, characterized in that: The tertiary air enters the decomposition furnace (4) at a fixed height without the need for upper and lower air divisions. Each fuel feeding point is provided with a coal nozzle. The feeding points and coal nozzles on the same fuel feeding surface 1 and the fuel feeding surface 2 are symmetrically distributed along the circumference.

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