A method for adjusting the air and pulverized coal balance of a tangentially fired boiler with corners cut

Abstract

The present invention provides a method for leveling the air and pulverized coal in a tangentially fired boiler with four-corner tangential burners. The present invention includes a four-drive leveling valve device and, based on the on-line measurement data of air and pulverized coal, the central controller adjusts the opening combinations of the four-drive leveling valves to level the air and pulverized coal velocities and concentrations in each air and pulverized coal pipeline, so as to ensure the balanced output of each layer of burners during the operation of the tangentially fired boiler with four-corner tangential burners, which is of great significance to the safety and economy of the boiler.

Description

Technical Field

[0001] The present invention relates to the field of combustion control of tangentially fired boilers with four corners, specifically to the technical field of four-wheel drive leveling technology for tangentially fired boilers with four corners based on on-line monitoring of primary air powder, and particularly to a method for leveling air powder in a tangentially fired boiler with four corners. Background Art

[0002] Currently, during the operation of coal-fired boiler units in thermal power plants, the uneven output of each burner has always been a problem that cannot be adjusted during operation, posing a potential safety hazard to the operation of the boiler.

[0003] In the design of the boiler, it is default that the output of each layer of burners is balanced. However, during actual operation, after the air powder in the coal mill is carried out of the coal mill by the primary air and reaches the four primary air powder pipelines at the outlet, there will be varying degrees of differences in the air powder speed and concentration entering each pipeline. When the differences in air powder speed and concentration in each pipeline are relatively large, the combustion dynamic field in the furnace will be skewed, resulting in coking and high-temperature corrosion. At the same time, the flame center will rise, the temperature of the reheater tube wall will rise, and the burnout rate will decrease. During stable combustion at low loads, since the outlet of the coal mill decreases significantly, the burners corresponding to the pipelines with low concentration in the primary air powder pipelines will experience unstable combustion, and seriously, the flame detection signal will be lost.

[0004] In summary, the following problems exist in the prior art: During the actual operation of a tangentially fired boiler with four corners, there are varying degrees of differences in the air powder speed and concentration in the four air powder pipelines at the outlet of the coal mill, resulting in uneven output of each layer of burners, and seriously, the flame detection signal will be lost, affecting the safety and economy of the boiler operation. Summary of the Invention

[0005] The present invention provides a method for leveling air powder in a tangentially fired boiler with four corners to solve the problem in the prior art that during the operation of a tangentially fired boiler with four corners (tangentially fired coal-fired boiler), there are varying degrees of differences in the air powder speed and concentration in the four air powder pipelines at the outlet of the coal mill, resulting in uneven output of each layer of burners, and seriously, the flame detection signal will be lost, so as to ensure the balanced output of burners during the operation of a tangentially fired boiler with four corners and improve the safety and economy of the boiler operation.

[0006] For this purpose, the present invention proposes a method for leveling air powder, and particularly a method for leveling air powder in a tangentially fired boiler with four corners.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for leveling air powder in a tangentially fired boiler with four corners includes the following steps:

[0009] 1), Install a set of four-wheel drive leveling valves on the powder feeding pipelines at the outlets of the separators of each coal mill respectively;

[0010] 2) The DCS performs on-line monitoring on the air-powder velocity and air-powder concentration in the outlet pipeline of the coal mill to obtain on-line monitoring data of air-powder.

[0011] 3) The DCS introduces the on-line monitoring data of air-powder into the PLC, and the PLC calculates the on-line monitoring data of air-powder in the air-powder pipeline to obtain the average value of the on-line monitoring data of air-powder in the air-powder pipeline.

[0012] 4) Based on the average value of the on-line monitoring data of air-powder in the air-powder pipeline, the central controller (central control cabinet) performs opening combination adjustment on the four-wheel leveling valve to level the air-powder velocity and air-powder concentration in the air-powder pipeline.

[0013] Further, one end of the four-wheel leveling valve is connected to the coal mill through the powder delivery pipeline at the separator outlet, and the other end is connected to the burner through the pulverized coal pipeline.

[0014] Further, the four-wheel leveling valve is installed on the vertical pipeline at the outlet of each coal mill separator.

[0015] Further, the four-wheel leveling valve includes a valve body 1, a valve core baffle, a valve core drive shaft and a drive motor; the valve body 1 includes: a circumferentially closed side wall and a cylindrical hollow region surrounded by the side wall, the bottom end of the hollow region is the inlet end, and the top end of the hollow region is the outlet end. The valve core baffle is arranged at the outlet end on the top of the valve body. One end of the valve core baffle is hinged to the side wall on the top of the valve body 1 through the valve core drive shaft, and the other end of the valve core baffle is a movable end that can be opened and closed up and down; the valve core baffle is connected to the valve core drive shaft and is driven by the valve core drive shaft to open and close; the valve core drive shaft is connected to the drive motor and is arranged on the side of the valve body.

[0016] Further, the side wall on the top of the valve body 1 is alternately connected by straight line segments and arc segments to form a circumferentially closed area.

[0017] Further, the valve core drive shaft is arranged on the straight line segment, and both ends of the valve core drive shaft are connected to the arc segments respectively.

[0018] Further, except for the valve core baffle, the rest of the top of the valve body 1 is a hollow region.

[0019] Further, the hollow region is divided into five regions, and the five regions include a hollow region 6 at the central position on the top of the valve body 1 and the other four regions; the hollow region 6 communicates with the other four regions.

[0020] Furthermore, the valve core drive shaft is strip-shaped and there are four of them, namely the first valve core drive shaft 7, the second valve core drive shaft 8, the third valve core drive shaft 9 and the fourth valve core drive shaft 10; the first valve core drive shaft 7 and the third valve core drive shaft 9 are parallel to each other, the second valve core drive shaft 8 and the fourth valve core drive shaft 10 are parallel to each other, and the first valve core drive shaft 7 and the second valve core drive shaft 8 are perpendicular to each other.

[0021] Furthermore, the valve core baffle is of a rectangular structure and there are four of them, namely the first valve core baffle 2, the second valve core baffle 3, the third valve core baffle 4 and the fourth valve core baffle 5; the structures and sizes of the four valve core baffles are the same.

[0022] Furthermore, the other four regions are fan-shaped regions, and the area of each fan-shaped region is smaller than the area of each valve core baffle.

[0023] The present invention is a method for leveling the air-powder velocity and air-powder concentration in an air-powder pipeline by performing opening combination adjustment on a four-wheel drive leveling valve based on online air-powder measurement data. This method creatively applies the four-wheel drive leveling valve device.

[0024] The valve body 1 of this four-wheel drive leveling valve includes: a circumferentially closed side wall and a cylindrical hollow region surrounded by the side wall. The bottom end of the hollow region is the inlet end, and the top end of the hollow region is the outlet end. The valve core baffle is arranged at the outlet end on the top of the valve body. One end of the valve core baffle is hinged to the side wall on the top of the valve body 1 through the valve core drive shaft, and the other end of the valve core baffle is a movable end that can be opened and closed up and down; the valve core baffle is connected to the valve core drive shaft and is driven by the valve core drive shaft to open and close, so as to achieve coal powder leveling. Compared with the prior art, the beneficial effects of the present invention are: through the hollow type without a central axis design of the four-wheel drive leveling valve, the interference of non-adjustment components of the existing special leveling valve to the coal powder flow is avoided, the pipeline air resistance and energy consumption are not increased in the non-adjustment state, and the damage to the equipment body caused by coal powder erosion is reduced; at the same time, this four-wheel drive leveling valve does not require a reduced diameter design, which can reduce the physical space of the equipment and is convenient for adapting to the on-site working conditions and installation and maintenance.

[0025] In addition, the valve core drive shaft is strip-shaped and there are four of them, namely the first valve core drive shaft 7, the second valve core drive shaft 8, the third valve core drive shaft 9, and the fourth valve core drive shaft 10; the first valve core drive shaft 7 and the third valve core drive shaft 9 are parallel to each other, the second valve core drive shaft 8 and the fourth valve core drive shaft 10 are parallel to each other, and the first valve core drive shaft 7 and the second valve core drive shaft 8 are perpendicular to each other; the valve core baffle is of a rectangular structure and there are four of them, namely the first valve core baffle 2, the second valve core baffle 3, the third valve core baffle 4, and the fourth valve core baffle 5; the four valve core baffles have the same structure and size; the valve core baffle can, through multiple independent drive motors and valve core drive shafts, under the unified coordination of the central controller 15, adjust for flow rate deviation and concentration deviation simultaneously or separately according to the actual air-powder measurement data, reducing the mutual interference during the parameter adjustment process. Description of the Drawings

[0026] Figure 1 Schematic top view of the four-wheel drive leveling valve of the present invention;

[0027] Figure 2 Flow chart of the method of the present invention.

[0028] Explanation of the reference numerals in the drawings: 1, valve body; 2, first valve core baffle; 3, second valve core baffle; 4, third valve core baffle; 5, fourth valve core baffle; 6, hollow area; 7, first valve core drive shaft; 8, second valve core drive shaft; 9, third valve core drive shaft; 10, fourth valve core drive shaft; 11, first drive motor; 12, second drive motor; 13, third drive motor; 14, fourth drive motor; 15, central controller; 16, fan-shaped area; 17, fan-shaped area; 18, fan-shaped area; 19, fan-shaped area; 20, disassembly and maintenance baffle; 21, disassembly and maintenance baffle; 22, disassembly and maintenance baffle; 23, disassembly and maintenance baffle. Detailed Description of the Invention

[0029] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the present invention will now be described.

[0030] The present invention provides a method for leveling air-powder in a tangentially fired boiler with four corners, including the following steps, as Figure 2 shown:

[0031] 1. Install a set of four-wheel drive leveling valves on the vertical pipe section of each primary air-powder pipeline at the outlet of each pulverizer.

[0032] 2. Connect the on-line speed and concentration signals of the air-powder from the DCS (Distributed Control System) to the PLC of this system.

[0033] The DCS conducts on-line monitoring of the air-powder velocity and air-powder concentration in the mill outlet pipeline to obtain on-line monitoring data of air-powder; the on-line monitoring data of air-powder is introduced into the PLC through the DCS. The PLC calculates the on-line monitoring data of air-powder in the pipeline to obtain the average value of the on-line monitoring data of air-powder in the air-powder pipeline. The air-powder measurement data is introduced into the PLC through hard wiring. The PLC is a local control cabinet, which calculates the air-powder data in the four air-powder pipelines to obtain the average value, and sends the adjustment instruction to the corresponding four-wheel leveling valve to adjust each valve core baffle.

[0034] 3. Configure the DCS boiler mill screen to enable the operator to adjust and control the timely monitoring of whether the air-powder is balanced.

[0035] The DCS is connected to the central controller through the Modbus protocol, and the interface is RS485.

[0036] 4. Conduct equipment and system commissioning after the mill starts and operates normally to ensure the normal operation of the system.

[0037] A four-wheel leveling valve device according to the present invention, as Figure 1 shown, includes a valve body 1, a valve core baffle, a valve core drive shaft and a drive motor; the valve body 1 includes: a circumferentially closed side wall and a cylindrical hollow region surrounded by the side wall. The bottom end of the hollow region is the inlet end, and the top end of the hollow region is the outlet end. The valve body is a hollow cylinder structure without a central axis, so that when adjusting the coal powder flow deviation in the powder delivery pipeline, non-adjusting components have no influence on the system adjustment; the valve core baffle is arranged at the outlet end on the top of the valve body. One end of the valve core baffle is hinged to the side wall on the top of the valve body 1 through the valve core drive shaft. The other end of the valve core baffle is a movable end, which can be opened and closed up and down. The opening and closing angle between the other end of the valve core baffle and the top plane of the valve body is an acute angle or a right angle. The valve core baffle is connected to the valve core drive shaft and is driven by the valve core drive shaft to open and close; the valve core drive shaft is connected to the drive motor and is arranged on the side of the valve body.

[0038] The valve core drive shaft and the drive motor are arranged on the outer side of the valve body.

[0039] Further, the valve core drive shaft is strip-shaped, and the number is four, which are the first valve core drive shaft 7, the second valve core drive shaft 8, the third valve core drive shaft 9 and the fourth valve core drive shaft 10 respectively; the first valve core drive shaft 7 and the third valve core drive shaft 9 are parallel to each other, the second valve core drive shaft 8 and the fourth valve core drive shaft 10 are parallel to each other, and the first valve core drive shaft 7 and the second valve core drive shaft 8 are perpendicular to each other.

[0040] The number of the driving motors is four, namely a first driving motor 11, a second driving motor 12, a third driving motor 13, and a fourth driving motor 14. The valve core baffle is adjusted to open and close up and down according to system instructions through a plurality of independent driving motors and a valve core driving shaft, so as to realize the leveling of pulverized coal. At the same time, the multi-drive structure can enrich the system adjustment algorithms and strategies. Multiple independently driven valve core baffles can be adjusted according to the actual air-powder measurement data, simultaneously or separately, for flow rate deviation and concentration deviation under the unified coordination of the central controller 15, reducing the mutual interference during the parameter adjustment process.

[0041] The valve body and the valve core baffle are all wrapped with high wear-resistant ceramic materials. The valve core driving shaft has no contact with the pulverized coal, and the overall service life of the equipment exceeds 7 years.

[0042] Further, the side wall of the top of the valve body 1 is alternately connected by straight line segments and arc segments to form a circumferentially closed area, so as to arrange the valve core baffle at the top of the valve body 1.

[0043] Further, the valve core driving shaft is arranged on the straight line segment. The plane where the straight line segment is located is a vertical plane. Both ends of the valve core driving shaft are respectively connected with the arc segment, so as to firmly fix the valve core driving shaft and realize the up-and-down opening and closing adjustment of the valve core baffle.

[0044] Further, except for the valve core baffle, the rest of the top of the valve body 1 is a hollow area, so that when the valve core baffle is completely closed, the pipeline can still maintain a through-flow rate of more than 40%.

[0045] Further, the hollow area is divided into five areas. The five areas include a hollow area 6 at the center position of the top of the valve body 1 and the other four areas. The hollow area 6 communicates with the other four areas, so that when the four-wheel drive leveling valve is in a non-working state, the valve core baffle retracts against the side wall of the valve body, making the pipeline in a completely hollow state, and the side wall of the valve body and the non-working state valve core baffle are on the same vertical plane.

[0046] Further, the four-wheel drive leveling valve is connected with a coal mill through a powder feeding pipeline at the outlet of the coal mill separator from the inlet end, and is connected with a burner through a pulverized coal pipeline at the outlet end, so as to ensure that the pulverized coal flow deviation in each powder feeding pipeline at the outlet of the coal mill is within 10%, and at the same time meet the requirements of various on-site installation conditions.

[0047] The four-wheel drive leveling valve is installed on the powder feeding pipeline at the outlet of the coal mill separator. The best position is the vertical pipeline at the outlet of the coal mill separator. In special cases, it can be installed on the horizontal pipeline at the first wear-resistant elbow at the outlet of the coal mill separator.

[0048] Further, the first spool drive shaft 7, the second spool drive shaft 8, the third spool drive shaft 9, and the fourth spool drive shaft 10 are all located in a plane so that the spool baffles are in the same plane in the non-operating state.

[0049] The four-wheel drive leveling valve further includes disassembly, installation, and maintenance baffles. The number of disassembly, installation, and maintenance baffles is four, namely disassembly, installation, and maintenance baffle 20, disassembly, installation, and maintenance baffle 21, disassembly, installation, and maintenance baffle 22, and disassembly, installation, and maintenance baffle 23. The disassembly, installation, and maintenance baffles are arranged on the outer side of the valve body 1 and can protect the spool baffles.

[0050] Further, the spool baffles are rectangular structures, and the number is four, namely the first spool baffle 2, the second spool baffle 3, the third spool baffle 4, and the fourth spool baffle 5. The structures and sizes of the four spool baffles are the same, so that the four-wheel drive leveling valve does not require a diameter-changing design, and the physical space of the equipment can be reduced.

[0051] The spool baffles 2, spool baffle 3, spool baffle 4, and spool baffle 5 intersect to form a cross-shaped structure. Among them, the spool baffle 2 and the spool baffle 4 are set on the horizontal line of the cross-shaped structure and are arranged oppositely, and the spool baffle 3 and the spool baffle 5 are set on the vertical line of the cross-shaped structure and are arranged oppositely, aiming to control the four independent opening and closing directions of the four-wheel drive leveling valve.

[0052] Further, the other four regions are fan-shaped regions, namely fan-shaped region 16, fan-shaped region 17, fan-shaped region 18, and fan-shaped region 19. The area of each fan-shaped region is smaller than the area of each spool baffle, so that when the spool baffle is fully closed, the pipeline can still maintain a flow rate of more than 40%.

[0053] The four-wheel drive leveling valve device further includes a spool drive shaft fixing bracket. The spool drive shaft fixing bracket is arranged on the outer side of the valve body 1, and the spool drive shaft fixing bracket plays a role in fixing and supporting the spool drive shaft.

[0054] Based on the on-line monitoring of the pulverized coal and air mixture, the present invention adjusts the opening combination of the spool baffles belonging to the four-wheel drive leveling valve through the central controller to achieve the purpose of balancing the pulverized coal and air velocity and the pulverized coal and air concentration in each primary air and pulverized coal pipeline at the outlet of the coal mill. The four-wheel drive leveling valve device is connected to the coal mill through the pulverized coal conveying pipeline at the outlet of the coal mill separator from the inlet end, and the outlet end is connected to the burner through the pulverized coal pipeline. According to the measured data of the pulverized coal and air measurement system arranged between the device and the burner, under the unified coordination of the central controller 15, the intelligent actuator with bus communication function - the drive motor independently configured drives the spool drive shaft to rotate, and then drives the spool baffle arranged at the outlet end of the top of the valve body to open and close up and down through the spool drive shaft, so as to realize the leveling of the pulverized coal in each pulverized coal conveying pipeline.

[0055] The above are only illustrative specific embodiments of the present invention and are not intended to limit the scope of the present invention. Each component of the present invention can be combined with each other under the condition of no conflict. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for leveling air and pulverized coal in a tangentially fired boiler with corners cut, characterized in that, It includes the following steps: S1. Install a set of four-wheel drive leveling valves on the powder feeding pipelines at the outlets of the separators of each coal mill respectively; S2. Use DCS to on-line monitor the air-powder velocity and air-powder concentration in the outlet pipeline of the coal mill to obtain on-line monitoring data of air-powder; S3. Introduce the on-line monitoring data of air-powder into the PLC through DCS, and the PLC calculates the on-line monitoring data of air-powder in the air-powder pipeline to obtain the average value of the on-line monitoring data of air-powder in the air-powder pipeline; S4. Based on the average value of the on-line monitoring data of air-powder in the air-powder pipeline, the central controller adjusts the opening combination of the four-wheel drive leveling valve to level the air-powder velocity and air-powder concentration in the air-powder pipeline; The four-wheel drive leveling valve includes a valve body (1), a valve core baffle, a valve core drive shaft and a drive motor; the valve body (1) includes: a circumferentially closed side wall and a cylindrical hollow area surrounded by the side wall, the bottom end of the hollow area is the inlet end, the top end of the hollow area is the outlet end, the valve core baffle is arranged at the outlet end on the top of the valve body, one end of the valve core baffle is hinged to the side wall on the top of the valve body (1) through the valve core drive shaft, the other end of the valve core baffle is a movable end and can be opened and closed up and down; the valve core baffle is connected to the valve core drive shaft and is driven by the valve core drive shaft to open and close; the valve core drive shaft is connected to the drive motor and is arranged on the side of the valve body.

2. A method for leveling air and pulverized coal in a tangentially fired boiler according to claim 1, characterized in that, One end of the four-wheel drive leveling valve is connected to the coal mill through the powder feeding pipeline at the separator outlet, and the other end is connected to the burner through the pulverized coal pipeline.

3. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four corners according to claim 1, characterized in that, The four-wheel drive leveling valve is installed on the vertical pipeline at the outlet of the separator of each coal mill.

4. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four corners according to claim 1, characterized in that The side wall on the top of the valve body (1) is alternately connected by straight line segments and arc segments to form a circumferentially closed area.

5. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four corners according to claim 4, characterized in that, The valve core drive shaft is arranged on the straight line segment, and both ends of the valve core drive shaft are connected to the arc segments respectively.

6. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four-corner firing according to claim 1, characterized in that, Except for the valve core baffle, the top of the valve body (1) is a hollow area.

7. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four corners according to claim 6, characterized in that, The hollow area is divided into five areas, and the five areas include a hollow area (6) at the center position on the top of the valve body (1) and the other four areas; the hollow area (6) communicates with the other four areas.

8. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four-corner tangential firing according to claim 1, characterized in that, The valve core drive shaft is strip-shaped and has four numbers, which are the first valve core drive shaft (7), the second valve core drive shaft (8), the third valve core drive shaft (9) and the fourth valve core drive shaft (10); the first valve core drive shaft (7) and the third valve core drive shaft (9) are parallel to each other, the second valve core drive shaft (8) and the fourth valve core drive shaft (10) are parallel to each other, and the first valve core drive shaft (7) and the second valve core drive shaft (8) are perpendicular to each other.

9. A method for adjusting the air and pulverized coal leveling of a tangentially fired boiler with four-corner tangential firing according to claim 1, characterized in that, The valve core baffle is of rectangular structure and has four numbers, which are the first valve core baffle (2), the second valve core baffle (3), the third valve core baffle (4) and the fourth valve core baffle (5); the structures and sizes of the four valve core baffles are the same.

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