Under-fire air control method for burners that takes operating mode of coal pulverizing system into consideration, and device

Abstract

The present invention relates to an under-fire air control method for burners that takes the operating mode of a coal pulverizing system into consideration, and a device, which are applied to direct-flow burners arranged in a four-corner tangential manner. The method comprises: in response to an operation signal of a coal feeder A, using a coal pulverizing system A as a lowest-layer burner, calculating an AA-layer under-fire air damper opening degree on the basis of a coal feeding amount of the coal feeder A, and outputting same to an AA-layer damper actuator; and in response to the operation signal of the coal feeder A and a non-operation signal of a coal feeder B, using a coal pulverizing system B as the lowest-layer burner, calculating an AB-layer under-fire air damper opening degree on the basis of a coal feeding amount of the coal feeder B, and outputting same to an AB-layer damper actuator. Compared with the prior art, the present invention has the advantages of an improved fire-supporting effect, a high degree of automation, minimal disturbance to boiler combustion, etc.

Description

Burner underrun control method and equipment considering the operation mode of pulverizing system Technical Field

[0001] This invention relates to the field of burner control technology, and in particular to a burner bottom air control method and device that takes into account the operation mode of the pulverizing system. Background Technology

[0002] For DC burners with a four-corner tangential arrangement, the lowest secondary air baffle is often used as the flame support air. During boiler operation, the support air mainly supports the pulverized coal in the lower burner to prevent segregation and prevents the flame from rushing down into the cold ash hopper. This prevents coking in the cold ash hopper of the solid ash discharge furnace and the increase in the actual flame tangential diameter caused by the overall sinking of the flame, thus reducing the carbon content of the ash discharge. It plays a crucial role in the stability and economy of boiler combustion.

[0003] With the changing energy structure, the demand for deep peak shaving of thermal power units is becoming increasingly prominent, and the requirements for the boiler's low-load stable combustion capability are also higher. In order to take into account the steam temperature regulation during low-load operation, the lowest-level A-set pulverizing system is generally not used, and the next lower-level B / C-set pulverizing system is mainly used. For a 660MW unit, when the B-set pulverizing system is running with the lowest-level burner, the distance between the B-set burner nozzle and the AA-set secondary air nozzle is generally about 1.3 to 1.5 meters, while the distance between the A-set burner and the AA-set secondary air nozzle is 0.3 meters. This makes it impossible for the bottom-level bottom-supporting air to effectively support the flame, causing the flame to sink.

[0004] Considering the troubleshooting situation of the B-set pulverizing system, when the C-set pulverizing system is at the bottom, the distance between it and the AA-set is larger. In addition, during low-load operation, in order to control NOx generation, the opening of the burnout air damper may be larger, resulting in lower overall secondary air box pressure, secondary air velocity may deviate from the design value, the bottoming effect is worse, and the pulverized coal airflow will also tilt downwards simultaneously, leading to a decrease in the boiler's stable combustion capability.

[0005] In summary, there is currently a lack of a burner underrun control method to solve or partially solve the aforementioned problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art by providing a burner under-fire control method and device that takes into account the operation mode of the pulverizing system, so as to solve or partially solve the problem of unsatisfactory flaming effect caused by the switching of the pulverizing system.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] One aspect of the present invention provides a burner underrun control method that takes into account the operation mode of the pulverizing system, applied to a DC burner with a tangential arrangement at the four corners, comprising the following steps:

[0009] In response to the operating signal of coal feeder A, the A set of pulverizing system is used as the bottom burner. The bottom air opening of the AA layer is calculated based on the coal feed rate of the coal feeder A and output to the AA layer baffle actuator.

[0010] In response to the operating signal of coal feeder A and the non-operating signal of coal feeder B, the B set of pulverizing system is used as the bottom burner. Based on the coal feed rate of coal feeder B, the bottom air opening of the AB layer is calculated and output to the AB layer baffle actuator.

[0011] As a preferred technical solution, the following steps are also included:

[0012] In response to the operating signal of coal feeder A, the operating signal of coal feeder B, and the non-operating signal of coal feeder C, the pulverizing system C is used as the bottom burner. Based on the coal feed rate of coal feeder C, the bottom air opening of the BC layer is calculated and output to the BC layer baffle actuator.

[0013] As a preferred technical solution, the following steps are also included:

[0014] In response to the operating signal of at least one coal feeder, the pressure difference between the target large air box and the furnace outlet is calculated based on the acquired total air volume, and the actuators of the baffles of the non-bottom burners are subjected to negative feedback control based on the pressure difference between the target large air box and the furnace outlet.

[0015] As a preferred technical solution, the following steps are also included:

[0016] In response to receiving a baffle opening offset request, the actuator of the target baffle is controlled to match the target baffle with the requested opening offset.

[0017] As a preferred technical solution, the following steps are also included:

[0018] In response to the stop signal of the coal feeder C, the preset minimum purging and cooling flow rate corresponding to the opening degree is output to the BC layer baffle actuator;

[0019] In response to the stop signal of coal feeder B, the preset minimum purging cooling flow rate corresponding to the opening degree is output to the AB layer baffle actuator;

[0020] In response to the stop signal of coal feeder A, the preset minimum purging and cooling flow rate corresponding to the opening degree is output to the AA layer baffle actuator.

[0021] As a preferred technical solution, the baffle actuator uses a preset ratio of the current opening degree as the maximum rate of change, and adjusts the baffle opening degree under the premise that the rate of change is less than the maximum rate of change.

[0022] As a preferred technical solution, after obtaining the coal feed rate, filtering processing is also included.

[0023] As a preferred technical solution, the process of generating the operating signal of the coal feeder A includes:

[0024] In response to a remote start signal, the coal feeder A is started, generating a running signal for the coal feeder A.

[0025] In another aspect, an electronic device is provided, comprising: one or more processors and a memory, the memory storing one or more programs, the one or more programs including instructions for executing the aforementioned burner underrun control method taking into account the operating mode of the pulverizing system.

[0026] In another aspect, the present invention provides a computer-readable storage medium including one or more programs executable by one or more processors of an electronic device, said one or more programs including instructions for performing the aforementioned burner underrun control method taking into account the operating mode of the pulverizing system.

[0027] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0028] (1) Improved fire support effect: In response to the problem that the switching of the pulverizing system does not take into account the impact on the fire support effect, the present invention automatically determines and controls the baffle corresponding to the bottom burner according to the operating status of the coal feeder. The selection of the bottom air layer can be adjusted in a timely manner according to the changes of the lower pulverizing system, resulting in a better fire support effect.

[0029] (2) High degree of automation: The present invention can realize the fully automatic switching of the bottom air layer when the operation mode of the pulverizing system changes. No operator intervention is required throughout the process, and no complicated manual operation is required, which reduces the risk of accidents.

[0030] (3) Minimal disturbance to boiler combustion: During instruction switching, the rate of instruction change is limited, reducing disturbance to boiler combustion. Attached Figure Description

[0031] Figure 1 is a schematic diagram of the DC burner arrangement with tangential circles at the four corners in the embodiment;

[0032] Figure 2 is a schematic diagram of the secondary wind control command logic for layer AA in the embodiment;

[0033] Figure 3 is a schematic diagram of the secondary wind control command logic for layer AB in the embodiment;

[0034] Figure 4 shows the windbox / furnace pressure difference command logic in the embodiment. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] Example 1

[0037] To address the problems existing in the prior art, this embodiment provides a burner bottom air control method that takes into account the operation mode of the pulverizing system. It is applied to a DC burner with a tangential arrangement at the four corners as shown in Figure 1. Referring to Figure 1, (a) is a front view of the burner and (b) is a side view of the burner. The burner includes, from top to bottom, primary air B2, secondary air B0, primary air B1, secondary air AB, primary air A, direct-blown secondary air A1, and bottom secondary air AA layer.

[0038] The secondary air nozzles of the DC burner, arranged in a tangential pattern at the four corners, are mainly divided into the main combustion zone and the burnout air zone. For the main combustion zone, there are: a fuel air layer surrounding the pulverized coal nozzle, which constrains the pulverized coal airflow and increases the oxygen in the initial stage of combustion; a secondary air layer, which provides oxygen to the main combustion zone and helps the flame to swirl; and a bottom secondary air layer, which acts as a bottom support air layer. The fuel air layer and the secondary air layer are arranged alternately.

[0039] Taking the A-set pulverizing system as an example, the bottom-supporting secondary air of the AA layer is controlled by its own small baffle. The baffle opening command is a function calculation value of the coal quantity of the A coal feeder. As the coal quantity of the A-set pulverizing system increases, the opening is synchronized to meet the requirements of bottom-supporting air quantity and reducing the carbon content of slag. The small baffles of other secondary air layers control the overall secondary air box pressure to meet the requirements of secondary air velocity in different load sections.

[0040] When the B-set pulverizing system is the lower burner, the AB-layer secondary air damper no longer controls the secondary air box pressure, but instead tracks the coal quantity of the B coal feeder, using the AB-layer secondary air as the bottom air, while the AA-layer secondary air switch to control the secondary air box pressure.

[0041] Similarly, when C is the lowest layer, the secondary air in layers BC serves as the bottom support air. After the coal feeder stops operating, the corresponding secondary air opening is automatically set to the minimum opening of 10%.

[0042] The specific logic settings are as follows:

[0043] When the A-set pulverizing system is the lowest burner, the remote operation signal of feeder A is used as its operating basis. The AA-layer baffle command is the calculated value of the corresponding function of feeder A. See Figure 2 for the logic diagram of the AA-layer secondary air control command. The AND operation of feeder A's operating signal and feeder B's non-operating signal serves as the logical criterion for the lowest burner in the B-set pulverizing system. The AB-layer baffle command is the calculated value of the corresponding function of feeder B's coal quantity. See Figure 3 for the logic diagram of the AB-layer secondary air control command. The AND operation of feeder A's operating signal, feeder B's operating signal, and feeder C's non-operating signal serves as the logical criterion for the C-set pulverizing system to be the lowest burner. The BC-layer baffle command is the calculated value of the corresponding function of feeder C's coal quantity. Their corresponding function relationships are shown in Table 1.

[0044] Table 1. Correspondence between coal feed rate and bottom vent opening degree

[0045] In non-bottom-support air control mode, the AB / BC layer dampers follow the same control logic as other secondary air dampers, controlling the pressure difference between the secondary air box and the furnace negative pressure. This is controlled by the overall air box / furnace differential pressure command, the target value of which is a function of the total measured air flow rate. The deviation between the target and actual pressure differences is calculated using PID control to obtain the air box / furnace differential pressure command. See Figure 4 for the air box / furnace differential pressure command logic in this embodiment. Each secondary air damper is allowed to have an opening offset set based on the overall command to meet the oxygen requirements of different coal types. After the corresponding coal feeder stops operating, the corresponding secondary air damper closes to 10% to meet the minimum purging cooling flow rate requirement and no longer participates in regulation. Similarly, the AA layer damper closes to 10% after the A coal feeder stops operating and no longer participates in regulation. The functional correspondence between the large air box and the furnace outlet pressure difference is shown in Table 2.

[0046] Table 2. Relationship between Total Air Volume, Large Air Box, and Furnace Outlet Pressure Difference Function

[0047] During the switching between the bottom-supporting air control mode and the wind box / furnace differential pressure control mode, the baffles of the AA / AB / BC layers limit the rate of change of the command to 10% / min to prevent sudden changes in air volume from disturbing boiler combustion. To control the furnace cross-section and volumetric heat load, the secondary air of the CD layer is not considered as the bottom-supporting air to prevent excessive flame concentration and ensure the safety of the upper spiral tube.

[0048] This method has the following advantages:

[0049] (1) The selection of the bottom air layer can be adjusted in a timely manner according to the changes in the lower pulverizing system, resulting in a better pulverizing effect.

[0050] (2) The bottom air layer can be automatically switched when the operation mode of the pulverizing system changes, and no intervention from the operators is required throughout the process.

[0051] (3) During instruction switching, the rate of instruction change is limited to reduce disturbance to boiler combustion.

[0052] (4) The logic criteria for the operation of the bottom pulverizing system adopt the remote start and stop signal of the coal feeder, which will not make misjudgments when the coal feeder is tested on the spot, and will not switch prematurely during the start-stop purging phase of the pulverizing system.

[0053] Example 2

[0054] This embodiment provides an electronic device, including: one or more processors and a memory, wherein the memory stores one or more programs, the one or more programs including instructions for executing the burner underrun control method taking into account the pulverizing system operation mode as described in Embodiment 1.

[0055] Example 3

[0056] This embodiment provides a computer-readable storage medium including one or more programs executable by one or more processors of an electronic device, the one or more programs including instructions for performing a burner underrun control method taking into account the operating mode of a pulverizing system as described in Embodiment 1.

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A burner underrun control method considering the operation mode of a pulverizing system, characterized in that, The following steps are included in the application of a DC burner with a tangential arrangement at the four corners: In response to the operating signal of coal feeder A, the A set of pulverizing system is used as the bottom burner. The bottom air opening of the AA layer is calculated based on the coal feed rate of the coal feeder A and output to the AA layer baffle actuator. In response to the operating signal of coal feeder A and the non-operating signal of coal feeder B, the B set of pulverizing system is used as the bottom burner. Based on the coal feed rate of coal feeder B, the bottom air opening of the AB layer is calculated and output to the AB layer baffle actuator.

2. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, It also includes the following steps: In response to the operating signal of coal feeder A, the operating signal of coal feeder B, and the non-operating signal of coal feeder C, the pulverizing system C is used as the bottom burner. Based on the coal feed rate of coal feeder C, the bottom air opening of the BC layer is calculated and output to the BC layer baffle actuator.

3. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, It also includes the following steps: In response to the operating signal of at least one coal feeder, the pressure difference between the target large air box and the furnace outlet is calculated based on the acquired total air volume, and the actuators of the baffles of the non-bottom burners are subjected to negative feedback control based on the pressure difference between the target large air box and the furnace outlet.

4. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, It also includes the following steps: In response to receiving a baffle opening offset request, the actuator of the target baffle is controlled to match the target baffle with the requested opening offset.

5. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, It also includes the following steps: In response to the stop signal of the coal feeder C, the preset minimum purging and cooling flow rate corresponding to the opening degree is output to the BC layer baffle actuator; In response to the stop signal of coal feeder B, the preset minimum purging cooling flow rate corresponding to the opening degree is output to the AB layer baffle actuator; In response to the stop signal of coal feeder A, the preset minimum purging and cooling flow rate corresponding to the opening degree is output to the AA layer baffle actuator.

6. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, The baffle actuator uses a preset ratio of the current opening as the maximum rate of change, and adjusts the baffle opening as long as the rate of change is less than the maximum rate of change.

7. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, After obtaining the coal feed rate, filtering processing is also performed.

8. The burner underrun control method considering the operation mode of the pulverizing system according to claim 1, characterized in that, The process of generating the operating signal for coal feeder A includes: In response to a remote start signal, the coal feeder A is started, generating a running signal for the coal feeder A.

9. An electronic device, characterized in that, include: One or more processors and a memory, the memory storing one or more programs, the one or more programs including instructions for executing the burner underrun control method taking into account the operating mode of the pulverizing system as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, Includes one or more programs executed by one or more processors of an electronic device, said one or more programs including instructions for performing the burner underrun control method taking into account the operating mode of the pulverizing system as described in any one of claims 1-8.

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