A mill inlet air duct device, a primary air volume temperature equalization control system and method

Abstract

The present invention belongs to the field of control of the primary air duct at the inlet of a coal mill, and provides a coal mill inlet air duct device, a primary air volume equalizing and temperature regulating system and method. Among them, the coal mill inlet air duct device includes a hot primary main pipe, a plurality of hot primary air branch pipes arranged on one side of the hot primary main pipe and communicating with the hot primary main pipe, and a cold primary air pipe arranged on one side of the hot primary air branch pipe and communicating with the hot primary air branch pipe. An upstream hot primary opposed regulating door is provided in the hot primary air branch pipe and on the side where the cold primary air pipe interface is close to the hot primary main pipe, and a downstream hot and cold mixed air opposed regulating door is provided in the hot primary air branch pipe and on the side where the cold primary air pipe interface is far from the hot primary main pipe; a cold primary air regulating door is arranged in the cold primary air pipe at a certain angle. The present invention improves the flow equalization of the primary air duct at the inlet of the coal mill, improves the flow field and temperature field states at the measuring device under the premise of a small pressure loss, and improves the accuracy of the measurement of the air volume and temperature at the inlet of the coal mill.

Description

Technical Field

[0001] The present invention belongs to the technical field of the control of the primary air duct at the inlet of a coal mill, and particularly relates to an air duct device at the inlet of a coal mill, a primary air volume and temperature equalizing regulation system and method. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] In large-scale thermal power plant coal-fired boilers, a direct-fired pulverized coal system is generally adopted for coal mills. The stability and accuracy of the measurement of the primary air volume of the coal mill are crucial. It not only affects the accuracy of the air-coal ratio but also is one of the important factors for improving the economy and stability of the combustion system. However, there is generally a problem of uneven flow velocity in the pipe of the primary air duct of large coal mills. Due to complex actual operating conditions, the adverse guiding effect of the existing thermal primary air regulating valve on the flow field, defects of the air volume measuring instrument, etc., there are problems such as abnormal fluctuations in air volume measurement and poor regulating characteristics of the air damper, resulting in a large deviation between the measured primary air volume and the actual value, and further affecting the temperature of the primary air. In recent years, the structure of the primary air duct system has become more and more compact, the distance of the primary air duct is shorter, and the existence of conventional regulating valves makes the flow field in the pipe more complex, and even there is a phenomenon that the air volume measured by the air volume measuring device changes in the opposite direction to the opening of the air damper.

[0004] However, the current solutions focus on improving the accuracy of the measuring instrument and installing more flow equalizing devices additionally, which does not fundamentally solve the problem caused by uneven flow velocity of the upstream primary air, and installing more flow equalizing devices additionally makes the structure of the primary air duct complex, increases the cost and will bring a large pressure drop and increase the operating cost. In addition, when multiple pipes operate in parallel, the temperature of the mixed air in each pipe is different, resulting in uneven preheating of each coal mill due to uneven temperature, and causing uneven combustion. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes an air duct device at the inlet of a coal mill, a primary air volume and temperature equalizing regulation system and method. The present invention improves the flow equalization of the primary air duct at the inlet of the coal mill, improves the flow field and temperature field states at the measuring device under the premise of small pressure loss, and improves the accuracy of the measurement of the air volume and temperature at the inlet of the coal mill.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an air duct device at the inlet of a coal mill.

[0008] A mill inlet air duct device, comprising a hot primary main pipe, a plurality of hot primary air branch pipes arranged on one side of the hot primary main pipe and communicating with the hot primary main pipe, and a cold primary air pipe arranged on one side of the hot primary air branch pipes and communicating with the hot primary air branch pipes. An upstream hot primary split adjusting door is arranged inside the hot primary air branch pipe and on the side where the cold primary air pipe interface is close to the hot primary main pipe, and a downstream hot and cold mixed air split adjusting door is arranged inside the hot primary air branch pipe and on the side where the cold primary air pipe interface is far from the hot primary main pipe; a cold primary air adjusting door is arranged inside the cold primary air pipe at a certain angle.

[0009] In a second aspect, the present invention provides a regulating system for the uniform temperature of the primary air volume at the mill inlet.

[0010] A regulating system for the uniform temperature of the primary air volume at the mill inlet, comprising the mill inlet air duct device described in the first aspect. A temperature sensor is arranged inside the hot primary air branch pipe and at each mill inlet position. The temperature sensor is connected to a controller, and the controller is connected to a driving mechanism and a speed measuring device;

[0011] The temperature sensor is used to detect the temperature of each pipe entering the mill and send the temperature of each pipe entering the mill to the controller;

[0012] The speed measuring device is used to measure the local speed in the air duct downstream of the fan blade and send the local speed in the air duct downstream of the fan blade to the controller;

[0013] The controller is used to calculate the average temperature according to the temperature of each pipe entering the mill, select the fan blades in the hot primary air branch pipes that need to be regulated according to the difference between the temperature of each pipe entering the mill and the average temperature, and calculate the opening and closing angles of the fan blades according to the local speed in the air duct downstream of the fan blade; until the difference meets the set range.

[0014] Further, the speed measuring device includes a speed probe, or the driving mechanism includes a servo motor.

[0015] Further, the selection of the fan blades in the hot primary air branch pipes that need to be regulated includes: preferentially selecting the fan blades in the hot primary air branch pipe with the highest temperature and the fan blades in the hot primary air branch pipe with the lowest temperature for adjustment.

[0016] Further, the fan blades in the hot primary air branch pipes include the first fan blades of the upstream hot primary split adjusting door and the second fan blades of the downstream hot and cold mixed air split adjusting door.

[0017] In a third aspect, the present invention provides a method for regulating the uniform temperature of the primary air volume at the mill inlet.

[0018] A method for regulating the average temperature of the primary air volume at the inlet of a coal mill, using the primary air volume average temperature regulation system described in the second aspect, includes:

[0019] A temperature sensor collects the temperature of each pipe entering the coal mill and sends the temperature of each pipe entering the coal mill to the controller;

[0020] A speed measuring device collects the local speed in the air duct downstream of the fan blade and sends the local speed in the air duct downstream of the fan blade to the controller;

[0021] The controller calculates the average temperature according to the temperature of each pipe entering the coal mill, selects the fan blade in the hot primary air branch pipe that needs to be regulated according to the difference between the temperature of each pipe entering the coal mill and the average temperature, and calculates the opening and closing angle of the fan blade according to the local speed in the air duct downstream of the fan blade; until the difference meets the set range.

[0022] Further, the process of calculating the opening and closing angle of the fan blade according to the local speed in the air duct downstream of the fan blade adopts the following formula:

[0023]

[0024] Where Δα is the change angle of the fan blade of the fan, V i is the local speed (the speed of each measuring point) in the air duct downstream of the fan blade, is the average speed (the arithmetic average of the speeds of each measuring point) in the air duct downstream of the fan blade, the angle α is the initial angle, which is the included angle between the fan blade and the pipe cross-section.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1) The present invention creatively proposes a primary air volume regulation system at the inlet of a coal mill that has both a flow regulation function and a rectifying and flow equalizing function. The above regulation can ensure that the temperature of each mixed air is uniform, avoid the problem of uneven preheating caused by uneven temperature, and cause uneven combustion.

[0027] 2) Based on the existing primary air duct of the coal mill, a primary air volume regulation system at the inlet of the coal mill with flow regulation, rectifying and flow equalizing functions is creatively proposed, and a system for dynamically regulating the flow according to the temperature of different primary air pipes. It includes two multi-leaf opposed regulating valves upstream and downstream to achieve dual control and dual flow equalization, solves the problem from the source of uneven primary air flow velocity at the inlet of the coal mill, has obvious flow equalizing effect, can improve the accuracy and stability of the measurement of the air volume and temperature at the inlet of the coal mill, and then improve the economy and stability of the combustion system. And the device has a simple structure, avoids the problems of excessive pressure drop and increased operating cost caused by the additional installation of a flow equalizing device in the existing flow equalizing technology, and has high economic benefits. Description of the Drawings

[0028] The attached drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0029] Figure 1 Fig. 1 shows a schematic diagram of the overall structure of the primary air duct at the inlet of a coal mill for a primary air volume and temperature regulation system provided by the present invention;

[0030] Figure 2 Fig. 2 shows a partial three-dimensional structure diagram of a primary air volume and temperature regulation system at the inlet of a coal mill provided by the present invention in an open state;

[0031] Figure 3 Fig. 3 shows a partial three-dimensional structure diagram of a primary air volume and temperature regulation system at the inlet of a coal mill provided by the present invention in a closed state;

[0032] Fig. 4(a) shows an isometric view of one of the multi-leaf opposed regulating dampers in the air volume regulation system of the present invention in an open state;

[0033] Fig. 4(b) shows an isometric view of one of the multi-leaf opposed regulating dampers in the air volume regulation system of the present invention in a closed state;

[0034] Figure 5 Fig. 5 shows the velocity distribution and streamline diagram at the vertical central section of the primary air duct at the inlet of a coal mill in the prior art;

[0035] Figure 6 Fig. 6 shows the velocity distribution and streamline diagram at the vertical central section of the primary air duct at the inlet of a coal mill using the regulation system of the present invention;

[0036] Fig. 7(a) shows the velocity distribution contour map at the cross-section of the air duct using the prior art;

[0037] Fig. 7(b) shows the velocity distribution contour map at the cross-section of the air duct using the regulation system provided by the present invention;

[0038] Figure 8 Fig. 8 shows a schematic diagram of the system structure;

[0039] Figure 9 Fig. 9 shows a schematic diagram of the fan blade angle;

[0040] Figure 10 Fig. 10 shows a block diagram of the damper opening control process for temperature regulation;

[0041] Figure 11 Fig. 11 shows the layout diagram of temperature sensors arranged at the inlet position of the coal mill;

[0042] In the figure, 1 is the primary hot air main pipe, 2 is the primary hot air branch pipe, 3 is the primary cold air pipe, 4 is the upstream primary hot air opposed regulating valve, 5 is the downstream hot and cold mixed air opposed regulating valve, 6 is the primary cold air regulating valve, and 7 is the temperature measuring device at the inlet of the coal mill. Detailed implementation manners

[0043] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0044] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0045] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0046] In the present invention, terms such as "upper", "lower", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present invention and do not specifically refer to any component or element of the present invention. It should not be construed as a limitation to the present invention.

[0047] In the present invention, terms such as "connected" and "coupled" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those skilled in the relevant scientific research or technology in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances and should not be construed as a limitation to the present invention.

[0048] Embodiment 1

[0049] This embodiment provides a coal mill inlet air duct device, which includes a primary hot air main pipe, a plurality of primary hot air branch pipes arranged on one side of the primary hot air main pipe and communicating with the primary hot air main pipe, and a primary cold air pipe arranged on one side of the primary hot air branch pipe and communicating with the primary hot air branch pipe. An upstream primary hot air opposed regulating valve is provided inside the primary hot air branch pipe and on the side where the interface of the primary cold air pipe is close to the primary hot air main pipe, and a downstream hot and cold mixed air opposed regulating valve is provided inside the primary hot air branch pipe and on the side where the interface of the primary cold air pipe is far from the primary hot air main pipe; a primary cold air regulating valve placed at a certain angle is provided inside the primary cold air pipe.

[0050] As one or more embodiments, the upstream hot primary opposed regulating door includes a plurality of first fan blades. Among them, a certain distance can be set between the first fan blades, which is set artificially, and the specific distance range is determined according to the inner diameter of the hot primary air branch pipe and the number of fan blades.

[0051] As one or more embodiments, the downstream cold and hot mixed air opposed regulating door includes a plurality of second fan blades. Among them, a certain distance can be set between the second fan blades, which is set artificially, and the specific distance range is determined according to the inner diameter of the hot primary air branch pipe and the number of fan blades.

[0052] As one or more embodiments, the opening direction of the first fan blade and the opening direction of the second fan blade are perpendicular to each other. For example, the opening direction of the first fan blade can be vertical and the opening direction of the second fan blade can be horizontal; or, the opening direction of the first fan blade can be horizontal and the opening direction of the second fan blade can be vertical. Or, the opening direction of the first fan blade is inclined, and the opening direction of the second fan blade is also inclined and perpendicular to the opening direction of the first fan blade.

[0053] Embodiment 2

[0054] Figures 1-9 Shows the overall structural schematic diagram of the primary air duct at the inlet of a coal mill using a primary air volume and temperature regulation system for the inlet of a coal mill according to the present invention. As Figure 1 shown, a primary air volume and temperature regulation system for the inlet of a coal mill includes a primary air duct at the inlet of the coal mill. The primary air duct at the inlet of the coal mill includes a hot primary air main pipe 1, hot primary air branch pipes 2 (more than 3 branch pipes, actually there may be more), and cold primary air pipes 3;

[0055] A plurality of parallel mixing pipes are provided, and temperature sensors are provided at each coal mill inlet position for detecting the temperature of the mixed air after mixing in each mixing pipe; the multiple temperature values are weighted and averaged to obtain an average temperature. Then, the difference between the temperature of each mixing pipe and the average temperature is used to adjust the angle of the regulating door according to the size of the difference to adjust the amount of hot air entering the mixing pipe. The opening of the air door can be adjusted according to the temperature of different air pipes to make the temperature of each air pipe roughly the same.

[0056] When the temperature difference is within a reasonable range, keep running in the current state. When the temperature difference is not within a reasonable range, adjust.

[0057] Define the temperature relative variance as:

[0058]

[0059] Where T i is the temperature measured by each temperature sensor, It is the average value of all temperature sensors. When the relative temperature variance exceeds 20%, first adjust the two mixing pipes with the highest and lowest temperatures. For the pipe with the highest temperature, adjust the included angle of the fan blades of the adjusting door to be smaller, and for the pipe with the lowest temperature, adjust the included angle of the fan blades to be larger, so as to adjust the amount of hot air entering, and then adjust the temperature difference after mixing to reach a reasonable range, as small as possible less than 20%.

[0060] Then adjust the remaining two mixing pipes with the highest and lowest temperatures according to the above steps; until the temperature difference finally reaches a reasonable range.

[0061] Preferably, both the cold air and the hot air come from the atmospheric environment. Part of the cold air forms the primary hot air after passing through the air preheater. The heat of the primary hot air comes from the flue gas, but the cold air does not mix with the flue gas in the preheater, but is indirectly heat-exchanged. The outlet of the primary hot air leads to the coal mill, which is used to preheat and dry the pulverized coal in the coal mill.

[0062] The primary cold air directly comes from the atmosphere. The primary hot air is mixed with the primary cold air because the temperature of the primary hot air is higher than the temperature allowed by the coal mill (explosion may occur at too high a temperature), and it must be adjusted to a suitable temperature by mixing in cold air.

[0063] This embodiment proposes a primary air flow rate regulating system at the inlet of the coal mill that has the function of flow regulation and also has the functions of rectifying and equalizing the flow. The above regulation can ensure that the temperature of each mixing air is uniform, avoid the problem of uneven preheating caused by uneven temperature, and avoid the problem of uneven combustion.

[0064] In each of the primary hot air branch pipes 2, an upstream primary hot air opposed regulating door 4 (including the fan blades, see Figure 2 -4) is provided before intersecting with the primary cold air pipe 3, and an upstream primary hot air opposed regulating door 5 (the fan blades are the same as those of 4, but rotated 90° in direction) is provided after intersecting with the primary cold air pipe 3. The opposed regulating doors 4 and 5 can achieve the functions of double control of the flow rate and double equalization of the flow, solve the problem from the source of the uneven flow rate of the primary air at the inlet of the coal mill, have an obvious equalizing effect, can improve the accuracy and stability of the measurement of the air volume and temperature at the inlet of the coal mill, and further improve the economy and stability of the combustion system. And the device has a simple structure, avoids the problems of excessive pressure drop and increased operation cost caused by the additional installation of an equalizing device in the existing equalizing technology, and has high economic benefits.

[0065] The hot air flow rate needs to be carefully controlled. The opposed regulating damper in this embodiment has both the function of equalizing the flow and the function of flow regulation. In the past, a common damper (a damper facing one direction) was generally used to control the flow rate, and an orifice plate was used for flow equalization. However, the common damper will deflect the primary hot air from one side to the other side, which will exacerbate the degree of flow disorder in the pipeline. And the orifice plate will significantly reduce the flow area, resulting in a large resistance.

[0066] As long as the opposed dampers are not in a nearly closed state, they have little impact on the flow area. The fan blades of the opposed dampers cause the air flow to bypass both sides of the blades, rather than guiding the air flow to one side as in the case of ordinary dampers. During this process, a certain resistance is imposed on the flow, reducing the flow velocity in the area with a higher flow velocity and inducing the air flow to pass through the area with a lower flow velocity. Especially when two sets of mutually perpendicular opposed dampers are used, the flow equalization effect is better. At the same time, changing the angle of the fan blades of the opposed dampers (the angle between the fan blades and the cross-section) can also play a role in regulating the flow rate. By comparison, the flow field of the conventional damper with an orifice plate shows obvious velocity non-uniformity ( Figure 5 、 Figures 7(a)-7(b) ), while the flow field of the opposed dampers is relatively uniform ( Figure 6 、 Figures 7(a)-7(b) ).

[0067] Optionally, the cold primary air regulating damper 6 has a multi-blade structure, and the adjacent blades have an opposed regulating structure. By setting the opposed regulating structure, the inlet air of the input cold primary air can be made uniform.

[0068] Optionally, the upstream hot primary air regulating damper 4 and the downstream primary air regulating damper 5 are arranged in different directions. The fan blades of the upstream hot primary air regulating damper 4 open horizontally, and the fan blades of the downstream primary air regulating damper 5 open vertically, or the fan blades of the upstream hot primary air regulating damper 4 open vertically, and the fan blades of the downstream primary air regulating damper 5 open horizontally. When the regulating damper is partially opened, each pair of opposed fan blades can guide the flow to both sides. The upstream hot primary air regulating damper 4 can cause the flow velocity to spread in the horizontal direction, and the downstream primary air regulating damper 5 can cause the flow velocity to spread in the vertical direction; after the regulating dampers 4 and 5 are combined, since the two sets of dampers are perpendicular to each other, the flow can be spread in four directions, namely horizontal and vertical, and the degree of uniformity is higher.

[0069] Optionally, during the regulation of the two sets of opposed dampers, the opening angles of all the fan blades in the hot primary air branch pipes can be controlled. Preferably, the opening angles are controlled by servo motors. Generally, one hot primary air branch pipe is controlled by two servo motors. One servo motor controls all the fan blades of the hot primary air regulating damper 4 in one hot primary air branch pipe, and the other servo motor controls all the fan blades of the downstream primary air regulating damper 5. When the local flow velocity is too high, the fan blades can adopt a smaller angle, thereby increasing the local resistance and causing the gas to move in the direction with a lower flow velocity, further improving the uniformity of the flow field.

[0070] Optionally, the width of each fan blade of the multi-leaf opposed regulating door can be determined according to the actual primary air distribution in the pipeline. Preferably, the pipeline diameter is 9-11 times the blade spacing, preferably 10 times. With the above dimensions, the flow equalization effect is obvious, which can improve the accuracy and stability of the air volume and temperature measurement at the mill inlet, and then improve the economy and stability of the combustion system. Moreover, the device has a simple structure, avoiding the problems of excessive pressure drop and increased operating costs caused by the additional installation of flow equalization devices in the existing flow equalization technology, and has high economic benefits.

[0071] Optionally, since the air volume regulating system adopts an opposed form, it not only has the function of flow regulation, but also has the functions of rectification and flow equalization.

[0072] Optionally, the air volume regulating system can achieve double control and double flow equalization to achieve a better flow equalization effect. The primary hot air from the primary hot air main pipeline will first pass through the upstream primary hot air regulating door. After passing through this regulating door, its rectification effect makes the velocity distribution of the primary hot air relatively uniform. Subsequently, the primary cold air is connected. Due to the different temperatures and velocities of the primary cold air, the uneven velocity and temperature after mixing increase. The mixed primary air passes through the second multi-leaf opposed regulating door again, and a better uniform distribution of velocity and temperature can be achieved after passing through the second regulating door.

[0073] Optionally, all the fan blades of the same primary hot air regulating door 4 of the multi-leaf opposed regulating door are adjusted together. Preferably, the opening angle of the fan blades is controlled by a servo motor. Since the pressure loss caused by the fan blades at different opening and closing angles is different, the rectification and flow equalization effects are also different. Due to the T-shaped structure formed by the primary hot air main pipeline and the mixing pipeline, the incoming primary hot air itself has uneven velocity. Therefore, the fan blade angle can be finely adjusted according to the velocity distribution state of the incoming primary hot air.

[0074] Preferably where Δα is the change angle of the fan blade, V i is the local velocity (the velocity at each measuring point) in the air duct downstream of the fan blade, is the average velocity (the arithmetic mean of the velocities at each measuring point) in the air duct downstream of the fan blade. The angle α is the initial angle, which is the angle between the fan blade and the cross-section of the pipeline. Optionally, it is 25-35°, and further preferably 30°. Due to the uneven flow velocity at different positions in the air duct, the local velocity in the air duct downstream of the fan blade referred to here is the air duct flow velocity at the position of the velocity probe.

[0075] When the blade angle is small (tending to the closed state), the flow resistance is large; conversely, when the blade angle is large (tending to the open state), the flow resistance is small. If the flow velocity is high at a certain location, the nearby blades should be at a small angle (tending to close), which can induce the fluid to flow towards the area with a large blade angle, achieving a flow equalization effect. If all the blade angles are the same, although a flow equalization effect can also be achieved, the effect is slightly worse.

[0076] By adjusting the above-mentioned angles, it is possible to achieve the best flow equalization effect under the minimum resistance.

[0077] Optionally, several velocity probes are placed near the downstream of the blades. For example, a pitot tube is set within 1 m downstream of the blades for velocity measurement. According to the velocities measured by each velocity probe and the calculated average velocity, the opening angle of the blades is calculated. The opening angle is the included angle α between the blade and the cross-section of the pipeline, as Figure 9 shown.

[0078] Optionally, the width of each blade of the multi-blade opposed regulating door can be determined according to the actual primary air distribution in the pipeline. Preferably, the width = blade spacing, and the blade spacing = pipeline diameter / 10. This is because different blade sizes will also bring different pressure losses and different rectifying and flow equalization effects, which can be determined according to the incoming primary air velocity distribution and temperature distribution state to achieve a better flow equalization effect.

[0079] Optionally, both the upstream hot primary air regulating door 4 and the downstream primary air regulating door 5 are opposed dampers, and the blade spacing of the air damper is 210 mm. The cold primary air pipeline 3 is a cold air duct with a diameter of 800 mm; the hot and cold primary air mixing pipeline 2 is a hot air duct with a diameter of 2100 mm.

[0080] Embodiment 3

[0081] The present invention provides a method for regulating the temperature and flow rate of primary air at the inlet of a coal mill, including the following steps:

[0082] 1) Read the data of the temperature sensors set at each coal mill inlet position, and perform weighted averaging on multiple temperature values to obtain the average temperature. Then, calculate the difference between the temperature of each mixing pipeline and the average temperature;

[0083] 2) When the temperature difference is within a reasonable range, maintain the current operating state. When the temperature difference is not within a reasonable range, perform adjustment;

[0084] 3) When the temperature difference is not within a reasonable range, first adjust the two mixing pipelines with the highest and lowest temperatures. For the pipeline with the highest temperature, reduce the included angle of the regulating door blades, and for the pipeline with the lowest temperature, increase the blade included angle, thereby adjusting the amount of hot air entering, and adjusting the temperature difference after mixing to reach a reasonable range;

[0085] 4) Then adjust the remaining two mixing pipes with the highest and lowest temperatures according to the above steps until the temperature difference reaches a reasonable range.

[0086] A number of temperature sensors are installed at the outlets of multiple mixing air ducts, i.e., at the inlet 7 of each coal mill. Figure 11 The black dot is a sensor) which is used to detect the mixed air temperature T in each mixing duct. i . The outlet temperature of the mixing duct T i The values are weighted averaged according to the flow rate to obtain the average temperature Then, the difference between the temperature of each mixing duct and the average temperature is adjusted according to the size of the difference, and the angle of the upstream hot primary air regulating door 4 is adjusted to adjust the amount of hot air entering the mixing duct. When the temperature difference is within a reasonable range, keep running. When the temperature difference is not within a reasonable range, make adjustments. First adjust the two mixing ducts with the highest temperature and the lowest temperature. For the one with the highest temperature, reduce the angle of the regulating door blades, and for the one with the lowest temperature, increase the angle of the blades, so as to adjust the amount of hot air entering, and thus adjust the temperature difference after mixing to a reasonable range. Then adjust the remaining two mixing ducts with the highest temperature and the lowest temperature, and adjust according to the above steps; until the temperature difference finally reaches a reasonable range. The above adjustment can ensure that the temperature of each mixed air is uniform, avoid uneven preheating caused by uneven temperature, and cause uneven combustion.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A primary air volume and temperature uniform regulation system at the inlet of a coal mill, characterized in that, It includes a coal mill inlet air duct device, which includes a hot primary main pipe, several hot primary air branch pipes arranged on one side of the hot primary main pipe and communicating with the hot primary main pipe, and a cold primary air pipe arranged on one side of the hot primary air branch pipe and communicating with the hot primary air branch pipe. It is characterized in that an upstream hot primary opposed regulating gate is provided inside the hot primary air branch pipe and on the side where the cold primary air pipe interface is close to the hot primary main pipe, and a downstream hot and cold mixed air opposed regulating gate is provided inside the hot primary air branch pipe and on the side where the cold primary air pipe interface is far from the hot primary main pipe; a cold primary air regulating gate placed at a certain angle is provided inside the cold primary air pipe; A temperature sensor is provided inside the hot primary air branch pipe and at each coal mill inlet position, the temperature sensor is connected to a controller, and the controller is connected to a driving mechanism and a speed measuring device; The temperature sensor is used to detect the temperature of each pipe entering the coal mill and send the temperature of each pipe entering the coal mill to the controller; The upstream hot primary opposed regulating gate includes several first fan blades; The downstream hot and cold mixed air opposed regulating gate includes several second fan blades; The speed measuring device is used to measure the local speed inside the air duct downstream of the fan blade and send the local speed inside the air duct downstream of the fan blade to the controller; The controller is used to calculate the average temperature according to the temperature of each pipe entering the coal mill, select the fan blades inside the hot primary air branch pipe that need to be regulated according to the difference between the temperature of each pipe entering the coal mill and the average temperature, and calculate the opening and closing angle of the fan blade according to the local speed inside the air duct downstream of the fan blade; until the difference meets the set range.

2. The primary air volume temperature equalization control system at the inlet of the coal mill according to claim 1, wherein The opening direction of the first fan blade and the opening direction of the second fan blade are in a perpendicular relationship.

3. The primary air volume temperature equalization control system at the inlet of the coal mill according to claim 1, wherein The speed measuring device includes a velocity probe, or, the driving mechanism includes a servo motor.

4. The primary air volume temperature equalizing control system at the inlet of the coal mill according to claim 1, wherein Selecting the fan blades inside the hot primary air branch pipe that need to be regulated includes: selecting the fan blades inside the hot primary air branch pipe with the highest temperature and the fan blades inside the hot primary air branch pipe with the lowest temperature for adjustment.

5. A method for regulating and controlling the uniform temperature of the primary air volume at the inlet of a coal mill, characterized in that, Adopting the coal mill inlet primary air volume equalizing control system according to any one of claims 1-4, including: The temperature sensor collects the temperature of each pipe entering the coal mill and sends the temperature of each pipe entering the coal mill to the controller; The speed measuring device collects the local speed inside the air duct downstream of the fan blade and sends the local speed inside the air duct downstream of the fan blade to the controller; The controller calculates the average temperature according to the temperature of each pipe entering the coal mill, selects the fan blades inside the hot primary air branch pipe that need to be regulated according to the difference between the temperature of each pipe entering the coal mill and the average temperature, and calculates the opening and closing angle of the fan blade according to the local speed inside the air duct downstream of the fan blade; until the difference meets the set range.

6. The primary air volume equalizing temperature control method at the mill inlet according to claim 5, characterized in that The process of calculating the opening and closing angle of the fan blade according to the local speed inside the air duct downstream of the fan blade adopts the following formula: Among them is the variable angle of the fan blade, V i is the local velocity in the downstream air duct of the fan blade, is the average velocity in the downstream air duct of the fan blade, angle is the initial angle, which is the included angle between the fan blade and the cross-section of the pipeline.

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