A coal-fired boiler with emissions monitoring

Abstract

The utility model relates to gas emission monitoring technical field especially discloses a kind of discharging coal-fired boiler that can monitor. The device includes furnace, flue gas system, water circulation system, shell, flue and sampling tube, water circulation system contains 6 annular arrays of straight water pipe, downcomer and tube sheet, which makes working medium circulation by water circulation system, flue gas system provides heat for shell, flue discharges smoke and provides sufficient flue gas sample for sampling tube, sampling tube collects flue gas sample and detects, monitoring device is installed on flue and monitors flue gas emission, to realize real-time early warning of soot, short-circuit risk and obtain flue gas flow velocity vector and other key parameters, cooperate with high-speed signal processing unit to realize data real-time transmission and analysis. The utility model solves the technical problem that traditional smoke pot heat exchange is insufficient, traditional sampling tube collected flue gas sample is poor in representativeness, and traditional monitoring device is single, leading to monitoring data behindhand.

Description

Technical Field

[0001] This utility model relates to the field of gas emission monitoring technology, and in particular to a coal-fired boiler capable of monitoring emissions. Background Technology

[0002] In the industrial production sector, coal-fired boilers, as core energy supply equipment, are widely used in chemical, manufacturing, and heating industries. Their operating efficiency and emission monitoring performance directly affect a company's production benefits and environmental compliance. Currently available traditional coal-fired boilers, after long-term use, have gradually revealed several technical shortcomings, making it difficult to meet the current dual demands of efficient heat exchange and precise environmental monitoring.

[0003] From the perspective of heat exchange efficiency, the flue gas flow path design of traditional coal-fired boilers often has defects. Some boilers use direct-vent flues or simple guide structures, resulting in short residence time of flue gas in the furnace and turbulent flow field. A large amount of high-temperature flue gas is discharged directly without sufficient heat exchange with the water circulation system, resulting in wasted heat energy. At the same time, the water pipe layout in the water circulation system is unreasonable, and dead zones for working fluid flow are prone to appear in some areas, further reducing heat exchange efficiency and increasing the enterprise's coal consumption costs. In addition, the flue gas guide components of traditional boilers are mostly single straight plate structures, which cannot guide the flue gas to uniformly flush the heat exchange surface, easily causing local overheating or insufficient heat exchange, affecting the overall operational stability of the boiler.

[0004] In terms of emissions monitoring, with increasingly stringent environmental regulations, enterprises have a growing need for real-time monitoring of boiler exhaust emissions. However, traditional boiler monitoring solutions have significant shortcomings. Most boilers insert sampling tubes directly into the flue gas duct without considering the non-uniformity of the flue gas flow field, resulting in poor representativeness of the collected flue gas samples and an inability to accurately reflect the composition and concentration of the exhaust gas. Some sampling tubes lack internal pretreatment structures, allowing large dust particles to easily clog sampling channels or contaminate sensors, shortening the lifespan of monitoring equipment and increasing maintenance frequency and costs. Furthermore, traditional monitoring often relies on a single sensor, only acquiring basic parameters such as temperature and concentration. It is difficult to obtain real-time information such as flue gas velocity vectors and pressure pulsations, and cannot promptly warn of problems such as flue gas ash accumulation and airflow short circuits. This leads to delayed monitoring data, affecting enterprises' timely adjustments to boiler operation and potentially resulting in environmental penalties for exceeding emission standards.

[0005] Furthermore, traditional coal-fired boilers have a low degree of overall structural integration, lacking coordinated design between the flue gas system, water circulation system, and monitoring devices. The installation positions of various components interfere with each other, not only occupying more factory space but also increasing the difficulty of equipment assembly and commissioning. Some boilers have poor sealing performance at the connection between the flue and the boiler shell, easily leading to flue gas leaks, which pollute the workshop environment and pose safety hazards. These problems make it difficult for traditional coal-fired boilers to meet the actual production needs of enterprises in terms of high efficiency, energy saving, and accurate environmental monitoring. There is an urgent need for a new type of coal-fired boiler that integrates high-efficiency heat exchange, accurate monitoring, and stable operation to solve the pain points of existing technologies and help enterprises achieve the dual goals of energy saving, cost reduction, and environmental compliance. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model provides a coal-fired boiler with monitorable emissions, solving the technical problems of insufficient heat exchange in traditional boilers, poor representativeness of flue gas samples collected by traditional sampling tubes, and outdated monitoring data due to the simplistic nature of traditional monitoring devices.

[0007] To achieve the above objectives, this utility model provides the following technical solution: A coal-fired boiler with monitored emissions includes a furnace, a flue gas system, a water circulation system, a boiler shell, a flue, and a sampling pipe. The flue gas system includes a flue gas outlet pipe and an annular convection flue. The water circulation system includes six annular arrays of straight water pipes, downcomers, and tube sheets. The annular convection flue includes an outer smoke wall, an inner smoke wall, a straight smoke baffle, and three annular arrays of arc-shaped guide plates. The outer smoke wall and the inner smoke wall are arranged coaxially to form an annular channel. The straight smoke baffle is fixedly connected to the inner side of the outer smoke wall and the outer side of the inner smoke wall. The arc-shaped guide plates are fixedly connected to the outer smoke wall and their upper surfaces face the direction of the exhaust duct.

[0008] Preferably, a grate is detachably installed below the furnace chamber, a boss is fixedly provided below the grate, a base is fixedly connected to the bottom of the boss, and a base angle iron hoop is fixedly provided at the bottom of the base; a furnace door is opened on the side wall of the furnace chamber.

[0009] Preferably, one end of the flue gas outlet pipe is welded to the inside of the furnace shell, and the flue gas outlet pipe forms a 30-degree angle with the axial direction of the furnace shell. Three trapezoidal guide ribs in an annular array are fixedly installed inside the flue gas outlet pipe, and the thick end face of the trapezoidal guide ribs is fixedly connected to the inner wall of the flue gas outlet pipe. The other end of the flue gas outlet pipe is fixedly connected to the inlet end of the annular convection flue, and the joint is sealed.

[0010] Preferred configuration: The straight smoke baffle is positioned away from the flue gas outlet pipe and is fully welded to the inner side of the outer smoke wall and the outer side of the inner smoke wall; The three arc-shaped guide plates are arranged in a ring array and fixedly connected to the upper half of the outer smoke wall. The upper end of the arc-shaped guide plates is close to the exhaust duct to guide the flue gas to converge into the exhaust duct.

[0011] Preferably, the tube sheet is fixedly connected to the top of the inner smoke wall, together forming two independent sealed cavities, one above the other. The downcomer is located at the center of the inner smoke wall and is fixedly connected to the tube sheet to connect the upper and lower sealed cavities; the straight water pipe is fitted with a central tube seat on the outside, and the tube seat is fixedly connected to the tube sheet to realize the connection between the straight water pipe and the sealed cavity.

[0012] Preferred configuration: The boiler shell is fixedly connected to the upper part of the outer smoke wall, and the connection is sealed by welding; The flue gas duct runs vertically through the boiler shell wall. The lower end of the flue gas duct extends to the top of the annular convection flue gas duct, and the upper end of the flue gas duct extends to the outer side of the boiler shell. The connection between the flue gas duct and the boiler shell wall is sealed.

[0013] Preferred configuration: The flue gas exhaust duct is integrated with a Venturi-jet composite efficiency enhancement structure, which consists of a contraction acceleration section, a throat flow stabilization section, and a diffusion rectification section along the flue gas flow direction. The contraction acceleration section is a gradually narrowing cone shape along the direction of flue gas flow; The throat stabilizing section has a uniform diameter structure, and its inner wall has 6 inclined jet holes evenly distributed along the circumference. The jet holes penetrate the wall thickness of the flue and are connected to the outside atmosphere. The axis of the jet holes is inclined in the direction of the flue flow and forms a 30° angle with the axis of the flue. The diffusion and rectification section is a gradually expanding cone shape along the flue gas flow direction. Its inlet diameter is consistent with the outlet of the throat stabilization section, and its outlet diameter is restored to the inner diameter of the flue gas duct. A sampling tube is fixedly installed on the diffusion and rectification section. The sampling tube is at a 30-degree angle to the axis of the flue in the direction of the flue flow, and the lower end face of the sampling tube is close to the throat stabilization section. An infrared sensor and a continuous wave radar are installed on the diffusion and rectification section near the outlet of the flue. The continuous wave radar is equipped with an antenna, which is at a 45-degree angle to the axis of the flue.

[0014] Preferably, the sampling tube is equipped with three spiral ribs that are evenly distributed along the circumference. The upper and middle sections of the sampling tube are rotatably equipped with rotating blades. A central shaft passes through the center of the rotating blades and is connected to the inner wall of the sampling tube via a crossbar. Limiting discs are provided at both ends of the central shaft to prevent axial movement. An interface for installing a sensor is provided near the port of the sampling tube. The sensor contacts the flue gas inside the sampling tube through this interface to monitor parameters.

[0015] Preferably, the contraction acceleration section, the throat stabilization section, and the diffusion rectification section are smoothly connected in sequence without obvious steps or dead angles to ensure the continuous and stable flue gas flow field; the aperture and distribution density of the jet orifice are adapted to the flue gas mixing requirements to ensure the formation of a uniform oblique microjet.

[0016] Preferred configuration: The straight water pipe and the downcomer together form a working fluid circulation loop, and the working fluid can circulate between the straight water pipe, the upper and lower sealed cavities and the downcomer; the channel width of the annular convection flue is matched with the distribution density of the straight water pipe to ensure that the flue gas can fully flush the outer wall of the straight water pipe to achieve efficient heat exchange.

[0017] Compared with the prior art, the present invention has the following beneficial effects: First, this coal-fired boiler utilizes an optimized design of annular convection flue, with straight baffles guiding the flue gas to directionally scour the inner smoke wall. Combined with three annular arrays of arc-shaped guide plates, this achieves orderly flue gas convergence, preventing short-circuiting or localized stagnation and extending the residence time of the flue gas within the furnace. Simultaneously, the combination design of six annular arrays of straight water pipes and centrally located pipe supports ensures uniform heating of the working fluid and eliminates dead zones, effectively reducing heat waste. Furthermore, the trapezoidal guide ribs in the three annular arrays within the flue gas outlet pipe optimize the flue gas flow direction, further improving the heat exchange efficiency between the flue gas and water circulation system. Compared to traditional boilers, this reduces coal consumption and lowers energy costs for enterprises.

[0018] II. Achieving accurate and stable monitoring of exhaust emissions, helping enterprises achieve environmental compliance and reducing maintenance costs. The three-section design of the Venturi-jet composite enhancement structure breaks the low-speed stagnant zone of flue gas through the contraction acceleration section, eliminates concentration stratification through the oblique micro-jet in the throat stabilization section, and stabilizes the flow field in the diffusion rectification section, providing a uniform flow field environment for the sampling tube and monitoring device, solving the problem of poor representativeness in traditional sampling. The combination of spiral ribs and rotating blades inside the sampling tube can both concentrate the flue gas to ensure the sample volume and separate large particulate pollutants to avoid sensor contamination, thus reducing monitoring data errors. At the same time, the collaborative monitoring of infrared sensors and continuous wave radar can provide real-time early warning of dust accumulation and short-circuit risks, and obtain key parameters such as flue gas velocity vectors. With the help of a high-speed signal processing unit, real-time data transmission and analysis are achieved, reducing the frequency of manual inspections, extending the maintenance cycle of monitoring equipment, reducing maintenance costs, and ensuring that enterprises meet environmental regulations in real time and avoid penalties for exceeding emission standards. Attached Figure Description

[0019] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0020] Figure 1 This is a structural diagram of the coal-fired boiler of this utility model; Figure 2 This is a structural diagram of the coal-fired boiler of this utility model; Figure 3 This is a structural diagram of the smoke exhaust duct of this utility model; Figure 4 This is a structural diagram of the sampling tube of this utility model; Figure 5 This is a structural diagram of the flue gas outlet pipe of this utility model.

[0021] Legend: 1. Furnace shell; 2. Boiler shell; 3. Flue; 4. Sampling pipe; 5. Flue gas outlet pipe; 6. Straight water pipe; 7. Downcomer; 8. Tube sheet; 9. Outer smoke wall; 10. Inner smoke wall; 11. Straight baffle; 12. Arc-shaped guide plate; 13. Grate; 14. Boss; 15. Base; 16. Trapezoidal guide rib; 17. Continuous wave radar; 18. Venturi-jet composite enhancement structure; 19. Contraction acceleration section; 20. Throat stabilization section; 21. Diffusion rectification section; 22. Jet orifice; 23. Sensor; 24. Rotating blade; 25. Infrared sensor. Detailed Implementation

[0022] This application provides a coal-fired boiler with monitorable emissions, which effectively solves the technical problems of insufficient heat exchange in traditional boilers, poor representativeness of flue gas samples collected by traditional sampling tubes, and outdated monitoring data due to the single nature of traditional monitoring devices. Example

[0023] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the technical solution in this application embodiment effectively solves the technical problems of insufficient heat exchange in traditional smoke pots, poor representativeness of flue gas samples collected by traditional sampling tubes, and outdated monitoring data due to the single nature of traditional monitoring devices. The overall idea is as follows: Furnace structure: Furnace 1 adopts a cylindrical + semi-circular structure. A cast iron grate 13 is installed below furnace 1. A cast iron boss 14 is set below grate 13. The bottom of boss 14 is welded to steel plate base 15. The bottom of base 15 is fixed to the ground by 4 base angle iron hoops. Furnace door is opened on the side wall of furnace 1 for easy coal addition.

[0024] Flue gas system: The flue gas outlet pipe 5 is made of seamless steel pipe and is welded to the top of the furnace 1 at a 30° angle to the furnace 1 axis. Three trapezoidal guide ribs 16 are evenly distributed along the circumference of the flue gas outlet pipe 5 at 120°. The thick end face of the trapezoidal guide ribs 16 is fully welded to the inner wall of the flue gas outlet pipe 5. The annular convection flue consists of an outer smoke wall 9 and an inner smoke wall 10 forming an annular channel. The straight smoke baffle 11 is made of steel plate and is fully welded to the inner side of the outer smoke wall 9 and the outer side of the inner smoke wall 10 and is far away from the flue gas outlet pipe 5. Three arc-shaped guide plates 12 are evenly distributed and welded along the upper half of the outer smoke wall 9 at 120°. The upper end face of the arc-shaped guide plate 12 is inclined towards the flue gas duct 3.

[0025] Water circulation system: 6 straight water pipes 6 are made of seamless steel pipes and are evenly distributed (circular array) at 120° along the outer side of the inner smoke wall 10. The straight water pipes 6 are fitted with central through pipe seats, and the pipe seats are fully welded to the tube sheet 8. The tube sheet 8 is welded to the middle of the inner smoke wall 10 to form two sealed cavities, upper and lower. The downcomer 7 is a seamless steel pipe located at the center of the inner smoke wall 10. The middle end of the downcomer 7 is fully welded to the tube sheet 8, and the upper end of the downcomer 7 is fully welded to the bottom of the boiler shell 2.

[0026] Boiler shell and flue: Boiler shell 2 is a cylindrical + flat-top conical structure, which is fully welded to the upper part of the outer smoke wall 9; flue 3 is made of stainless steel pipe, which vertically penetrates the wall of boiler shell 2, and the lower end of flue 3 is located at the top of the annular convection flue.

[0027] Venturi-jet composite enhancement structure: The Venturi-jet composite enhancement structure 18 is integrally welded with the flue duct 3. The Venturi-jet composite enhancement structure 18 includes a bottom section contraction and acceleration section 19, a middle section throat stabilizing section 20 (the inner wall of the throat stabilizing section 20 has 6 inclined jet holes 22 evenly distributed along the circumference at 60°, the axis of the jet holes 22 is inclined in the direction of the flow at 30° with the axis of the flue duct 3, and the jet holes 22 penetrate the wall thickness of the flue duct 3), and an upper section diffusion and rectification section 21; the side wall of the diffusion and rectification section 21 is welded with a sampling tube 4 (the sampling tube 4 is a stainless steel tube). The sampling tube 4 is inclined at a 30° angle to the axis of the flue gas duct 3. The lower end face of the sampling tube 4 is close to the outlet of the throat stabilizing section 20. Three spiral ribs are welded along the circumference of the sampling tube 4 at a 120° angle. Stainless steel rotating blades 24 (which can rotate freely with the flue gas) are installed in the upper middle section of the sampling tube 4. A threaded interface is reserved near the port of the sampling tube 4 for installing the flue gas concentration sensor 23. An infrared sensor 25 and a continuous wave radar 17 are welded to the diffusion rectifier section 21 near the outlet of the flue gas duct 3. The antenna of the continuous wave radar 17 is fixed at a 45° angle to the axis of the flue gas duct 3.

[0028] Assembly of the furnace chamber and supporting structure: First, install the grate 13 under the furnace chamber 1, ensuring that the grate 13 fits tightly against the bottom of the furnace chamber 1 without any loose gaps; then, install the boss 14 under the grate 13, fixing the top of the boss 14 to the bottom of the grate 13 to form a stable support; install the base 15 at the bottom of the boss 14 and fix it by welding, ensuring that there is no relative displacement between the base 15 and the boss 14; finally, install the base angle iron hoop at the bottom of the base 15, fixing the entire furnace chamber 1 supporting structure to the preset position on the ground with the base angle iron hoop, ensuring that the furnace chamber 1 is level and without tilting deviation; open the furnace door at the preset position on the side wall of the furnace chamber 1, ensuring that the furnace door can be opened and closed flexibly and that there is no smoke leakage after closing.

[0029] Flue gas outlet pipe assembly: Weld one end of the flue gas outlet pipe 5 to a preset position inside the furnace 1, so that the flue gas outlet pipe 5 and the furnace 1 form a 30-degree angle along the axis, ensuring that the flue gas generated inside the furnace 1 can smoothly enter the flue gas outlet pipe 5; Install a ring array of trapezoidal guide ribs 16 inside the flue gas outlet pipe 5, so that the thick end face of the trapezoidal guide ribs 16 is fixedly connected to the inner wall of the flue gas outlet pipe 5. The installation of the trapezoidal guide ribs 16 must ensure that the position is symmetrical and without deviation.

[0030] Annular convection flue assembly: First, arrange the outer smoke wall 9 and the inner smoke wall 10 coaxially at a preset interval to form an annular channel; fix the straight smoke baffle 11 to the inner side of the outer smoke wall 9 and the outer side of the inner smoke wall 10, and ensure that the straight smoke baffle 11 is far away from the flue gas outlet pipe 5; then fix the three arc-shaped guide plates 12 to the upper half of the outer smoke wall 9 in an annular array, so that the upper surface of the arc-shaped guide plate 12 faces the flue gas outlet 3, ensuring that the flue gas can converge to the flue gas outlet 3 under the guidance of the arc-shaped guide plate 12.

[0031] Connecting the flue gas outlet pipe to the annular convection flue: Fix the other end of the flue gas outlet pipe 5 to the inlet end of the annular convection flue. The connection is sealed by welding to ensure that there is no leakage of flue gas and that all of it can enter the annular convection flue.

[0032] Tube sheet installation: The tube sheet 8 is fixedly connected to the top of the inner smoke wall 10 to form two independent sealed cavities. After the cavities are welded, a sealing test is required to ensure that there is no leakage of the working fluid.

[0033] Straight water pipe and pipe seat assembly: Install the through pipe seat on the outside of the straight water pipe 6, and fix the pipe seat to the pipe plate 8. Then install the 6 straight water pipes 6 with the pipe seat assembled in a ring array to ensure that the straight water pipe 6 and the pipe plate 8 are firmly connected and without loosening.

[0034] Downcomer installation: Install downcomer 7 at the center of the inner smoke wall 10, so that downcomer 7 is fixedly connected to tube sheet 8, ensuring that downcomer 7 is connected to the upper and lower sealed cavities. The top of downcomer 7 is connected to the bottom fixed pipe of boiler shell 2 to realize the circulation of working fluid.

[0035] Boiler shell installation: Fix the boiler shell 2 to the upper part of the outer smoke wall 9. The connection is sealed by welding to ensure that there is no gap between the boiler shell 2 and the outer smoke wall 9 and that it can withstand the working fluid pressure.

[0036] Installation of flue: The flue duct 3 is inserted through the wall of the boiler shell 2, so that the lower end of the flue duct 3 is located at the top of the annular convection flue, and the upper end of the flue duct 3 extends to the outside of the boiler shell 2. The connection between the flue duct 3 and the wall of the boiler shell 2 needs to be sealed to prevent flue gas leakage.

[0037] Assembly of the Venturi-Jet Composite Enhancement Structure: The Venturi-Jet Composite Enhancement Structure 18 is integrated with the flue gas duct 3. The bottom section 19 of the Venturi-Jet Composite Enhancement Structure 18 is a tapered cone along the flue gas flow direction. The inner wall of the middle throat section 20 is provided with an inclined jet hole 22, which penetrates the wall thickness of the flue gas duct 3 and communicates with the external atmosphere. The upper section 21 is a tapered cone along the flue gas flow direction, ensuring smooth connection of the three sections and no dead corners for flue gas stagnation. A sampling tube 4 is installed at a preset position in the diffusion and rectification section 21. The sampling tube 4 is at a 30-degree angle to the axis of the flue gas duct 3 along the flue gas flow direction. The lower end face is close to the throat stabilization section 20 to ensure that the flue gas after flow field optimization can be collected; a spiral rib is installed inside the sampling tube 4, a rotating blade 24 is installed in the upper middle section of the sampling tube 4, and a sensor 23 is installed near the port of the sampling tube 4. The sensor 23 must be installed to ensure full contact with the flue gas and be firmly fixed; an infrared sensor 25 and a continuous wave radar 17 are installed near the outlet of the flue gas duct 3 in the diffusion rectification section 21. The antenna on the continuous wave radar 17 is at a 45-degree angle to the axis of the flue gas duct 3 to ensure that the infrared sensor 25 and the continuous wave radar 17 can accurately monitor the flue gas parameters and that the antenna receives the signal without obstruction.

[0038] Working principle: The first step is to confirm that the furnace shell 1, flue gas system (including flue gas outlet pipe 5, outer smoke wall 9, inner smoke wall 10, straight smoke baffle 11, arc-shaped guide plate 12), water circulation system (including straight water pipe 6, downcomer 7, tube sheet 8), boiler shell 2, and exhaust duct 3 are securely connected and there is no risk of loosening or leakage; check that the sampling pipe 4, infrared sensor 25, continuous wave radar 17 and other monitoring components are installed normally and that the wiring is correct.

[0039] Working medium filling: The working medium is filled into the boiler shell 2. The filling amount must reach the preset liquid level. The sealed cavity formed by the tube sheet 8 and the inner smoke wall 10 is pre-filled with working medium.

[0040] Equipment debugging: Start the high-speed signal processing unit and check whether the infrared sensor 25 and the continuous wave radar 17 are working properly, and whether the data from sensor 23 can be accurately transmitted to the boiler control system; manually check whether the rotating blade 24 inside the sampling tube 4 can rotate freely without any jamming.

[0041] The second step is coal ignition and flue gas circulation: coal is added into the furnace 1 through the fireplace door on the side of the furnace 1 and ignited, so that the coal is fully burned on the grate 13; the generated flue gas gathers in the furnace 1 and enters the annular convection flue through the flue gas outlet pipe 5. Under the guidance of the trapezoidal guide ribs 16 in the flue gas outlet pipe 5, the flue gas flow direction is optimized; after entering the annular convection flue, the flue gas is blocked by the straight baffle plate 11 and directionally washes the inner smoke wall 10, providing heat for the working medium in the straight water pipe 6.

[0042] Working fluid circulation: The working fluid in the straight water pipe 6 absorbs heat from the flue gas and its temperature rises. It then flows upward along the straight water pipe 6 and enters the upper closed cavity formed by the tube sheet 8 and the outer smoke wall 9. The outer wall of the downcomer 7 comes into contact with the high-temperature flue gas and is heated. Condensate forms on the inner wall of the downcomer 7. The condensate flows into the lower closed cavity under the action of gravity, completing the working fluid circulation.

[0043] Flue gas treatment and monitoring: After the flue gas washes over the inner smoke wall 10, it converges downwards into the exhaust duct 3 under the guidance of the arc-shaped guide plate 12, and then flows upwards along the exhaust duct 3, entering the Venturi-jet composite enhancement structure 18; in the contraction acceleration section 19, the flue gas accelerates its flow using the Venturi effect, breaking the low-speed stagnant zone, and the flue gas components are initially mixed; when the high-speed flue gas flows through the throat stabilization section 20, a pressure difference is formed inside and outside the jet orifice 22, and a small amount of external air is drawn in to form an oblique micro-jet, which performs secondary stirring on the flue gas and eliminates concentration stratification; after entering the diffusion rectification section 21, the flue gas decelerates smoothly, and the flow field tends to stabilize, providing a stable monitoring environment for the monitoring device.

[0044] Flue gas sampling and parameter monitoring: After being smoothly decelerated by the diffusion and rectification section 21, the flue gas is directed into the sampling tube 4 (the sampling tube 4 is inclined at a 30° angle to the axis of the exhaust duct 3, with its lower end face close to the outlet of the throat stabilization section 20, ensuring that the collected flue gas is a sample after flow field optimization). When the flue gas flows through the middle and upper section of the sampling tube 4, it drives the stainless steel rotating blades 24 to rotate freely, separating large particulate pollutants in the flue gas during the process, preventing them from adhering and contaminating the subsequent sensor 23; at the same time, three spiral ribs welded along the circumference of the sampling tube 4 at 120° gather the dispersed flue gas, ensuring that the sensor 23 can obtain a sufficient and uniform flue gas sample. The threaded interface reserved near the port of the sampling tube 4 is used to fix and install the flue gas concentration sensor 23, ensuring seamless connection between sampling and detection.

[0045] The infrared sensor 25, installed in the diffusion rectifier section 21 near the outlet of the flue gas duct 3, monitors the flue gas temperature in real time. If abnormal temperature fluctuations occur, it can provide timely warnings of ash accumulation and flue gas short circuit risks in the annular convection flue (composed of outer smoke wall 9 and inner smoke wall 10) or the flue gas duct 3, facilitating timely cleaning and maintenance.

[0046] The continuous wave radar 17 has its antenna fixed at a 45° angle to the axis of the flue gas duct 3 (without signal obstruction). The signal emitted by the radar is reflected after contacting the particulate matter in the flue gas. The horizontal and vertical velocity components of the flue gas are calculated by Doppler frequency offset, and then the velocity vector is synthesized. At the same time, the continuous wave radar 17 synchronously captures the flue gas pressure pulsation signal and transmits it to the high-speed signal processing unit.

[0047] The high-speed signal processing unit calculates the velocity vector and pressure pulsation spectrum data transmitted by the continuous wave radar 17 in real time, and combines them with the pollutant concentration detected by the flue gas concentration sensor 23. After integrating all parameters, the data is transmitted to the boiler control system to realize real-time monitoring, abnormal early warning and dynamic adjustment of combustion conditions of coal-fired boiler exhaust gas emissions.

[0048] In the third step, after the flue gas washes over the inner smoke wall 10, it converges with the arc-shaped guide plate 12 to the bottom of the exhaust duct 3 and flows upward with the exhaust duct 3. When it enters the Venturi-jet composite enhancement structure 18, the flue gas is accelerated by the Venturi effect, breaking the original low-speed stagnant zone and allowing the flue gas components to mix initially. When the high-speed flue gas flows through the throat stabilization section 20, a pressure difference is formed inside and outside the jet hole 22 (the static pressure in the throat is lower than the external atmospheric pressure). A small amount of external air is drawn in through the jet hole 22, forming 6 oblique micro-jet streams in the throat stabilization section 20, which "secondarily stir" the flue gas and further eliminate concentration stratification. This allows the accelerated flue gas to decelerate smoothly and return to the original flow velocity of the exhaust duct 3, providing a stable flow field for the downstream monitoring device.

[0049] The fourth step is to stop adding coal and terminate combustion: Stop adding coal into the furnace. After the remaining coal in the furnace has been fully burned and the flue gas temperature has gradually decreased, stop the combustion process. Working fluid treatment: After the temperature of the working fluid in the water circulation system drops to a safe range, the working fluid is discharged from the preset discharge port to avoid the pipes from freezing and cracking at low temperatures; Equipment Inspection and Maintenance: After shutdown, check the operating status of each component, clean the slag in the furnace 1 and the accumulated ash in the annular convection flue and exhaust flue 3; check whether the rotating blade 24 and sensor 23 in the sampling tube 4 are intact, and replace them in time if damaged; check the seals of each connection part, and replace them in time if they are aged or damaged to ensure stable performance of the device during the next startup. Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A coal-fired boiler with monitorable emissions, comprising a furnace (1), a flue gas system, a water circulation system, a boiler shell (2), a flue gas duct (3), and a sampling pipe (4), characterized in that, The flue gas system includes a flue gas outlet pipe (5) and an annular convection flue, and the water circulation system includes six annular arrays of straight water pipes (6), downcomers (7) and tube sheets (8). The annular convection flue includes an outer smoke wall (9), an inner smoke wall (10), a straight smoke baffle (11), and three annular arrays of arc-shaped guide plates (12). The outer smoke wall (9) and the inner smoke wall (10) are arranged coaxially to form an annular channel. The straight smoke baffle (11) is fixedly connected to the inner side of the outer smoke wall (9) and the outer side of the inner smoke wall (10). The arc-shaped guide plate (12) is fixedly connected to the outer smoke wall (9) and its upper end faces the direction of the exhaust duct (3).

2. A coal-fired boiler with monitorable emissions as described in claim 1, characterized in that, A grate (13) is installed below the furnace chamber (1), a boss (14) is fixedly provided below the grate (13), a base (15) is fixedly connected to the bottom of the boss (14), and a base angle iron hoop is fixedly provided at the bottom of the base (15); a furnace door is opened on the side wall of the furnace chamber (1).

3. A coal-fired boiler with monitorable emissions as described in claim 1, characterized in that, One end of the flue gas outlet pipe (5) is welded to the inside of the furnace shell (1). The flue gas outlet pipe (5) forms a 30-degree angle with the furnace shell (1) axis. Three trapezoidal guide ribs (16) in an annular array are fixedly installed inside the flue gas outlet pipe (5). The thick end face of the trapezoidal guide ribs (16) is fixedly connected to the inner wall of the flue gas outlet pipe (5). The other end of the flue gas outlet pipe (5) is fixedly connected to the inlet end of the annular convection flue, and the joint is sealed.

4. A coal-fired boiler with monitorable emissions as described in claim 3, characterized in that, The straight smoke baffle (11) is set away from the flue gas outlet pipe (5) and is fully welded to the inner side of the outer smoke wall (9) and the outer side of the inner smoke wall (10); Three arc-shaped guide plates (12) are arranged in a ring array and fixedly connected to the upper half of the outer smoke wall (9). The upper surface of the arc-shaped guide plates (12) is close to the exhaust duct (3) to guide the flue gas to converge into the exhaust duct (3).

5. A coal-fired boiler with monitorable emissions as described in claim 1, characterized in that, The tube sheet (8) is fixedly connected to the top of the inner smoke wall (10) to form two independent sealed cavities, one above the other. The downcomer (7) is located at the center of the inner smoke wall (10) and is fixedly connected to the tube sheet (8) to connect the upper and lower sealed cavities; the straight water pipe (6) is fitted with a central tube seat on the outside, and the tube seat is fixedly connected to the tube sheet (8) to realize the connection between the straight water pipe (6) and the sealed cavity.

6. A coal-fired boiler with monitorable emissions as described in claim 1, characterized in that, The boiler shell (2) is fixedly connected to the upper part of the outer smoke wall (9), and the connection part is welded and sealed; The flue (3) penetrates vertically through the wall of the boiler shell (2). The lower end of the flue (3) extends to the top of the annular convection flue, and the upper end of the flue (3) extends to the outside of the boiler shell (2). The connection between the flue (3) and the wall of the boiler shell (2) is sealed.

7. A coal-fired boiler with monitorable emissions as described in claim 6, characterized in that, The flue (3) is integrated with a Venturi-jet composite enhancement structure (18). The Venturi-jet composite enhancement structure (18) is composed of a contraction acceleration section (19), a throat stabilization section (20), and a diffusion rectification section (21) along the flue gas flow direction. The contraction acceleration section (19) is a gradually narrowing cone shape along the direction of flue gas flow; The throat stabilizing section (20) has a uniform diameter structure, and its inner wall is evenly distributed with 6 inclined jet holes (22) along the circumference. The jet holes (22) penetrate the wall thickness of the flue and are connected to the outside atmosphere. The axis of the jet holes (22) is inclined in the direction of the flue flow and forms a 30° angle with the axis of the flue. The diffusion rectification section (21) is a gradually expanding cone shape along the flue gas flow direction. Its inlet diameter is consistent with the outlet of the throat stabilization section (20), and the outlet diameter is restored to the inner diameter of the flue gas duct. A sampling tube (4) is fixedly installed on the diffusion rectification section (21). The sampling tube (4) is at a 30-degree angle to the axis of the flue along the direction of the flue flow, and the lower end face of the sampling tube (4) is close to the throat stabilizing section (20). An infrared sensor (25) and a continuous wave radar (17) are installed on the diffusion rectification section (21) near the outlet of the flue (3). An antenna is provided on the continuous wave radar (17), and the antenna is at a 45-degree angle to the axis of the flue.

8. A coal-fired boiler with monitorable emissions as described in claim 7, characterized in that, The sampling tube (4) is fixed with three spiral ribs evenly distributed along the circumference; The upper middle section of the sampling tube (4) is rotatably equipped with a rotating blade (24). A central shaft is inserted through the center of the rotating blade (24). The central shaft is connected to the inner wall of the sampling tube (4) through a crossbar. Limiting discs are provided at both ends of the central shaft to prevent axial movement. An interface for installing a sensor (23) is provided near the port of the sampling tube (4). The sensor (23) contacts the flue gas inside the sampling tube (4) through this interface to achieve parameter monitoring.

9. A coal-fired boiler with monitorable emissions as described in claim 7, characterized in that, The contraction acceleration section (19), the throat stabilization section (20), and the diffusion rectification section (21) are smoothly connected in sequence without obvious steps or dead angles to ensure the continuous and stable flue gas flow field; the aperture and distribution density of the jet orifice (22) are adapted to the flue gas mixing requirements to ensure that a uniform oblique microjet can be formed.

10. A coal-fired boiler with monitorable emissions as described in claim 1, characterized in that, The straight water pipe (6) and the downcomer (7) together form a working fluid circulation loop, and the working fluid can circulate between the straight water pipe (6), the upper and lower sealed cavities and the downcomer (7); the channel width of the annular convection flue is adapted to the distribution density of the straight water pipe (6) to ensure efficient heat exchange.

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