Device for optimizing measurement and distribution uniformity of air volume at inlet of coal mill

Abstract

The utility model relates to the technical field of primary air of a thermal power plant, and discloses a device for optimizing air volume measurement and distribution uniformity at an inlet of a coal mill, which comprises a flow equalizing element, a rectifying element and a flow guide element which are all arranged in a primary air duct at the inlet of the coal mill and can be used independently or cooperatively; the arrangement direction of the flow equalizing elements or the flow rectifying elements is perpendicular to the circulation direction of the air inlet branch pipes. The arrangement direction of the flow guide elements is parallel to the circulation direction of the air inlet branch pipes. According to the utility model, the flow equalizing element, the rectifying element and the flow guiding element are used as adjusting means to adjust the air volume in the primary air duct and improve the air flow velocity uniformity, so as to optimize the air volume distribution uniformity at the inlet of each coal mill and improve the measuring precision of the air volume measuring element.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of thermal power plant primary air, especially relates to a device for optimizing coal mill inlet air volume measurement and distribution uniformity. BACKGROUND

[0002] At present, in the actual operation of numerous thermal power plants, the limitation of the structure arrangement of the hot primary air duct becomes one of the key factors restricting the stable operation of the coal mill. Due to the complex design of the air duct, too many elbows or different lengths of branch pipes, there is a significant deviation in the air volume distribution at the inlets of different coal mills. This deviation makes part of the coal mills obtain more air volume than required, while another part appears the "air shortage" phenomenon due to insufficient air volume, directly affecting the combustion efficiency and equipment life. Simply relying on the primary air regulating door for global adjustment can partially alleviate the problem, but cannot fundamentally eliminate the uneven distribution caused by structural defects, and it is urgent to realize precise regulation and control through technical means.

[0003] The short mixed section of the coal mill inlet air duct is another core pain point. Due to space limitations, the installation position of the primary air volume measurement element (such as pitot tube, Venturi tube, multi-point matrix type measurement element, etc.) often cannot meet the standard requirements, resulting in that the measurement point is in the unstable airflow area (such as the downstream of the elbow or the variable diameter section). This arrangement makes the measurement results disturbed by turbulence, vortex, etc., and the speed distribution CV value (coefficient of variation) is generally high (more than 20% before transformation), and the air volume display value and the actual value have a significant deviation. Due to the lack of accurate data, the operator cannot perform closed-loop control on the coal mill inlet air volume, further exacerbating the "air shortage" or "excessive air" problem, forming a vicious cycle. Insufficient air volume at the coal mill inlet will directly lead to insufficient drying of the pulverized coal, poor conveying, unstable combustion, NOx emission exceeding the standard, and even increased equipment vibration. Excessive air volume may cause the pulverized coal to be too fine, increase the power consumption for coal grinding, and further exacerbate the wear of the primary air duct. UTILITY MODEL CONTENTS

[0004] To solve the existing problems, the utility model provides a device for optimizing coal mill inlet air volume measurement and distribution uniformity, which aims to use flow uniformity elements, rectification elements and flow guide elements as adjustment means to adjust the air volume in the primary air duct and improve the airflow velocity uniformity, so as to optimize the inlet air volume distribution uniformity of each coal mill and improve the measurement accuracy of the air volume measurement element.

[0005] In order to achieve the above purpose, the utility model provides the following technical scheme.

[0006] The utility model relates to a device for optimizing the inlet air volume measurement and distribution uniformity of a coal mill, characterized in that it comprises a flow equalizing element, a flow rectifying element and a flow guiding element, which are arranged in the inlet primary air duct of the coal mill and can be used independently or in combination, the flow equalizing element or the flow rectifying element is arranged perpendicularly to the flow direction of the inlet air branch pipe, and the flow guiding element is arranged parallel to the flow direction of the inlet air branch pipe.

[0007] As a further improvement of the utility model, the flow equalizing element is in the form of a perforated plate with a thickness of 5-6 mm.

[0008] As a further improvement of the utility model, the flow rectifying element is formed by the staggered connection of a row of slats and a column of slats.

[0009] As a further improvement of the utility model, the flow guiding element is formed by the combination of a plurality of circular arc plates that are adapted to the elbow of the air duct.

[0010] As a further improvement of the utility model, the row of slats or the column of slats is retractable.

[0011] As a further improvement of the utility model, the row of slats or the column of slats is retractable along the width direction and is provided with a spring damper along the width direction.

[0012] As a further improvement of the utility model, the row of slats or the column of slats is retractable along the thickness direction and is provided with a spring damper along the thickness direction.

[0013] As a further improvement of the utility model, the flow equalizing element is arranged 0.5 m upstream of the air volume measurement element arranged in the inlet primary air duct of the coal mill.

[0014] As a further improvement of the utility model, when the inlet air volume of the coal mill is in the first third of the air volume values of the coal mills of the unit, the porosity of the flow equalizing element is 0.5-0.7.

[0015] As a further improvement of the utility model, when the inlet air volume of the coal mill is in the middle third of the air volume values of the coal mills of the unit, the porosity of the flow equalizing element is 0.7-0.8.

[0016] The utility model has the following beneficial effects:

[0017] The flow equalizing element, the rectifying element and the flow guiding element can be used alone or in combination, and are suitable for different air duct structures and air volume deviation scenarios; the flow equalizing element / rectifying element is perpendicular to the flow direction to enhance the rectifying effect, and the flow guiding element is parallel to the flow direction to reduce the resistance of the elbow, so as to realize the best matching of the air flow direction and the element function, effectively improve the measurement accuracy of the air volume at the inlet of the coal mill and the uniformity of the distribution, improve the working efficiency and stability of the coal mill, and reduce the equipment wear and operation failure caused by uneven air volume.

[0018] Preferably, the design of the thickness of the perforated plate being 5-6 mm can minimize the material cost and the additional pressure drop of the air duct while ensuring the structural strength, and will neither affect the strength and flow equalizing effect due to being too thin, nor increase unnecessary resistance due to being too thick, so as to balance the economy and practicability while ensuring the performance and prolong the service life of the element.

[0019] Preferably, the row of strip plates and the column of strip plates are staggered to form the rectifying element, and form a grid rectifying structure, which can effectively eliminate the air flow rotation and vortex, comb and rectify the air flow, and make the velocity distribution more uniform, thereby improving the measurement stability.

[0020] Preferably, the flow guiding element composed of the multiple layers of circular arc plates is matched with the curvature of the elbow of the air duct, gradually corrects the air flow direction, avoids the deflection and pressure loss caused by the sharp turn, and makes the air flow maintain a good flow state before entering the coal mill, which is beneficial to the uniform distribution and accurate measurement of the air volume; in the air shortage branch pipe, the air volume can be improved, and the noise and vibration can be reduced.

[0021] Preferably, by changing the extension degree of the strip plate, the rectifying effect can be optimized, and various complex air flow conditions can be better adapted to, thereby further improving the uniformity of the air volume distribution and the accuracy of the measurement.

[0022] Preferably, the strip plate is extendable along the width direction and is equipped with a spring damping element, can dynamically adapt to different air volume conditions with a cutting angle, absorbs the air flow pulsation energy through the spring damping element, stabilizes the wind speed fluctuation, and further improves the measurement and control accuracy.

[0023] Preferably, this design can make fine adjustment in the thickness direction according to the pressure and flow rate changes of the air flow, optimize the air flow channel, make the rectifying effect more accurate, and at the same time, align the air volume, so that the spring damping element can also play a buffering and protection role, thereby improving the reliability and stability of the equipment.

[0024] Preferably, the flow equalizing element is arranged at a position 0.5 meters upstream of the air volume measuring element, can make the air flow sufficiently and uniformly dispersed before reaching the measuring element, eliminate the influence of the unevenness of the air flow on the measurement result, thereby improving the accuracy of the air volume measurement, and providing more reliable data support for the operation control of the coal mill.

[0025] Preferably, when the coal mill inlet air volume is large (in the first third of the air volume value of each mill of the unit), the flow uniformizing element with a porosity of 0.5-0.7 is selected, the through area of the airflow can be reasonably controlled, the excessive air volume is properly adjusted and dispersed, the air volume entering the coal mill is more uniform, the local overloading or accelerated wear of the equipment caused by the excessive air volume is avoided, and the safe and stable operation of the coal mill is ensured.

[0026] Preferably, in the case that the coal mill inlet air volume is moderate (in the middle third of the air volume value of each mill of the unit), the flow uniformizing element with a porosity of 0.7-0.8 is adopted, the airflow can be uniformly dispersed while ensuring the smooth passing of the airflow, the air volume distribution is further optimized, the coal mill is operated under the optimal air volume condition, the combustion efficiency and the coal milling quality are improved, and the energy consumption and the equipment wear are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings described herein are for illustrative purposes only, and do not limit the scope of the present disclosure in any way. In addition, the shapes and proportional sizes of the components in the drawings are only illustrative, and are used to help understand the present disclosure, and are not specific limitations on the shapes and proportional sizes of the components. In the drawings:

[0028] Figure 1 A schematic view of the structure of the primary air duct at the inlet of the coal mill in Example 1;

[0029] Figure 2 A flow uniformizing element of the device for optimizing the air volume measurement and distribution uniformity at the inlet of the coal mill according to Example 1;

[0030] Figure 3 A flow uniformizing element of the device for optimizing the air volume measurement and distribution uniformity at the inlet of the coal mill according to Example 1;

[0031] Figure 4 A flow uniformizing element of the device for optimizing the air volume measurement and distribution uniformity at the inlet of the coal mill according to Example 1;

[0032] Figure 5 A flow uniformizing element of the device for optimizing the air volume measurement and distribution uniformity at the inlet of the coal mill according to Example 2 (elastic damping element arranged in the thickness direction);

[0033] Figure 6 A flow uniformizing element of the device for optimizing the air volume measurement and distribution uniformity at the inlet of the coal mill according to Example 2 (elastic damping element arranged in the width direction);

[0034] 1, the mill inlet primary air duct; 2, the air volume measuring element; 3, the flow uniformizing element; 4, the rectifying element; 5, the flow guiding element; 41, the row of strip plates; 411, the rectifying plate slot; 412, the rectifying expansion plate; 413, the spring damping element; 42, the column of strip plates. DETAILED DESCRIPTION

[0035] In order to make the personnel in the technical field better understand the technical solutions in the utility model, the technical solutions in the utility model embodiments will be clearly and completely described below in combination with the drawings in the utility model embodiments. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the personnel in the art without creative labor should belong to the protection scope of the utility model.

[0036] It should be noted that when an element is referred to as "being disposed on" another element, it can be directly on the other element or there can be a middle element. When an element is referred to as "being connected" to another element, it can be directly connected to the other element or there can be a middle element. The terms "vertical", "horizontal", "left", "right", and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiments.

[0037] Except for some terms which have been defined below, all the technical and scientific terms used herein have the same meanings as those commonly understood by the personnel in the technical field to which the utility model belongs. The terms used in the specification of the utility model herein are only for the purpose of describing the specific embodiments and are not intended to limit the utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0038] Embodiment 1

[0039] The embodiment also discloses a device for optimizing the air volume measurement and distribution uniformity of the mill inlet, comprising a flow uniformizing element 3, a rectifying element 4 and a flow guiding element 5, wherein the flow uniformizing element 3, the rectifying element 4 and the flow guiding element 5 are all arranged in the mill inlet primary air duct 1 and can be used independently or in combination; the arrangement direction of the flow uniformizing element 3 or the rectifying element 4 is perpendicular to the flow direction of the air inlet branch pipe; and the arrangement direction of the flow guiding element 5 is parallel or adaptive to the flow direction of the air inlet branch pipe.

[0040] Specifically, as shown in Figure 2 The flow uniformizing element 3 is a multi-hole plate structure. Preferably, the thickness of the multi-hole plate is 5-6 mm.

[0041] Specifically, as shown in Figure 3As shown, the rectifying element 4 is formed by the interlaced connection of the row strip plates 41 arranged in rows and the column strip plates 42 arranged in columns.

[0042] Specifically, as shown in Figure 4 As shown, the flow guiding element 5 is formed by the combination of multiple layers of circular arc plates adapted to the elbow of the air duct.

[0043] Specifically, the flow uniformizing element is arranged at a position 0.5 meters upstream of the air volume measuring element arranged in the inlet primary air duct of the coal mill. Generally, the air volume measuring element is arranged in the middle section of the straight pipe section (closest to the inlet of the coal mill) of the inlet primary air duct of the coal mill.

[0044] Specifically, when the inlet air volume of the coal mill is in the first third of the air volume value of each coal mill in the unit, the porosity of the flow uniformizing element is 0.5-0.7.

[0045] Specifically, when the inlet air volume of the coal mill is in the middle third of the air volume value of each coal mill in the unit, the porosity of the flow uniformizing element is 0.7-0.8.

[0046] Preferably, the large air volume group is installed with the flow uniformizing element with a porosity of 0.5-0.7, which significantly increases the air duct resistance (reduces the air volume), improves the measurement accuracy through the porous plate rectification, and avoids the problems of excessive air supply leading to excessively fine coal powder and increased power consumption for coal preparation.

[0047] Preferably, the medium air volume group is installed with the flow uniformizing element with a porosity of 0.7-0.8, which moderately increases the resistance to fine-tune the air volume while maintaining the measurement accuracy, balances the air volume distribution and system energy consumption, and avoids affecting the overall efficiency due to excessive resistance.

[0048] The use principle of optimizing the inlet air volume measurement and distribution uniformity of the coal mill includes:

[0049] When the hot primary air dampers of multiple coal mills are fully opened and the boiler is adjusted to full load, the initial measurement of the inlet air volume of the multiple coal mills is performed.

[0050] According to the inlet air volume of each coal mill, the flow uniformizing element 3, the rectifying element 4, or the flow guiding element 5 is used to adjust the air volume of the inlet air branch pipe of each coal mill.

[0051] The hot primary air dampers of multiple coal mills are again fully opened, and the boiler is adjusted to full load. The inlet air volume of the multiple coal mills is measured and compared with the measurement before the adjustment for evaluation.

[0052] As shown in Figure 1 As shown, the initial measurement of the inlet air volume is obtained by the air volume measuring element 2 installed near the outlet of the inlet primary air duct 1 of the coal mill.

[0053] Wherein, the air flow of each mill inlet is adjusted by using flow uniforming element 3, flow straightening element 4 or flow guiding element 5, including the following steps:

[0054] According to the air flow of each mill inlet, the mills are divided into large air flow group, medium air flow group and small air flow group;

[0055] The flow uniforming element 3 is arranged at a position 0.5 meters upstream of the air flow measuring element 2 of the mill in the large air flow group, and the porosity of the flow uniforming element 3 is 0.5-0.7;

[0056] The flow uniforming element 3 is arranged at a position 0.5 meters upstream of the air flow measuring element 2 of the mill in the medium air flow group, and the porosity of the flow uniforming element 3 is 0.7-0.8;

[0057] The flow straightening element 4 and the flow guiding element 5 are installed at a position 0.5 meters upstream of the air flow measuring element 2 of the mill in the small air flow group.

[0058] The specific implementation process of the reconstruction of a certain 1000 MW thermal power plant in the embodiment is as follows:

[0059] 1. Under the condition of full load of the boiler, the air flow of the mill inlet is measured manually in the field under the condition that the hot primary air door of all the mills is fully opened, and the air flow of the inlet of each mill is recorded. For example, there are 6 mills in total, and the two mills with the largest air flow, the two mills with the smallest air flow and the two mills with the intermediate air flow are selected.

[0060] 2. The two mills with the largest air flow are the mills with no air shortage, and the flow uniforming element 3 is added, and the porosity of the flow uniforming element 3 is 0.5-0.7. After the installation of the flow uniforming element 3, the air duct resistance of the two mills is increased, which reduces the air flow of the mill inlet, but improves the measurement accuracy of the measuring device.

[0061] 3. The two mills with the intermediate air flow (moderate air flow) also increase the flow uniforming element 3, and the porosity of the flow uniforming element 3 is 0.7-0.8. After the installation of the flow uniforming element 3, the air duct resistance of the two mills is increased by a small amount, which reduces the air flow of the mill inlet by a small amount, but improves the measurement accuracy of the measuring device.

[0062] 4. The two mills with the smallest air flow are the mills with air shortage, and the flow straightening element 4 combined with the flow guiding element 5 is added. After the addition of the device, the resistance of the two mills is reduced, the primary air flow of the mill inlet is increased, and the measurement accuracy of the measuring device is improved.

[0063] 5. The porosity of the flow uniforming element 3 and the flow straightening element 4 combined with the flow guiding element 5 are obtained by numerical simulation calculation to obtain an accurate design scheme.

[0064] Table 1 and Table 2 are the results of the air volume distribution of the mill inlet before and after the modification and the cross-sectional velocity distribution CV value of the measuring element. The CV value is used to statistically measure the degree of dispersion.

[0065] Table 1 Air volume distribution of the mill before and after the modification

[0066]

[0067] According to the inlet air volume of each mill before the modification, the six mills are grouped. Mill A and D are large air volume group mills, which use flow uniformizing element 3; mill B and C are medium air volume group mills, which use flow uniformizing element 3; mill E and F are small air volume group mills, which use rectifying element 4 and flow guiding element 5. The above Table 1 reflects that through the modification, the uniformity of the inlet air volume of each mill is obviously better.

[0068] Table 2 CV value of cross-sectional velocity distribution of measuring element before and after the modification

[0069]

[0070] The above Table 2 reflects that through the modification, the speed variation coefficient corresponding to the inlet air volume of each mill is reduced to 20%, which significantly improves the measurement accuracy of the air volume measuring element 2. Therefore, the modification meets the expectation, and the optimization result is acceptable.

[0071] Through the initial measurement of fully opening the hot primary air damper and adjusting to the full load of the boiler, the air volume benchmark data under the real working condition is obtained, which provides the basis for subsequent accurate allocation; the measurement is measured again and compared and evaluated to quantitatively verify the allocation effect, forming a closed-loop optimization process of “measurement-adjustment-verification”, which significantly improves the uniformity of air volume distribution and reduces the problem of unstable combustion caused by air volume deviation. Through the structured classification allocation, element function optimization and dynamic adjustment mechanism, the problems of air volume measurement distortion and uneven distribution of mill inlet in thermal power plants are systematically solved, which significantly improves the combustion efficiency and reduces the equipment wear and operation and maintenance cost.

[0072] The mills are divided into large air volume group, medium air volume group and small air volume group, and different elements are used accordingly to avoid “one-size-fits-all” adjustment; the flow uniformizing element improves the airflow uniformity through the multi-hole plate rectification and reduces the measurement error; the cooperation of the rectifying element and the flow guiding element reduces the resistance in the air shortage branch pipe and guides the smooth flow of airflow, while increasing the air volume, which solves the fundamental air shortage problem.

[0073] The air volume measuring element is arranged near the outlet of the mill inlet primary air duct to avoid the turbulent flow area such as elbow and variable diameter, so that the measurement point is in the stable airflow section, the cross-sectional velocity distribution CV value is reduced, and the measurement accuracy is improved, which provides reliable data support for air volume regulation and control.

[0074] Example 2

[0075] The difference between this embodiment and embodiment 1 is:

[0076] 1) The row of strip plates or the column of strip plates is retractable.

[0077] 2) The row of strip plates or the column of strip plates is retractable along the width direction, and a spring damper is arranged along the width direction.

[0078] 3) The row of strip plates or the column of strip plates is retractable along the thickness direction, and a spring damper is arranged along the thickness direction.

[0079] Specifically, the rectifying element 4 is formed by the row of strip plates 41 arranged in a row and the column of strip plates 42 arranged in a column being connected in an interleaved manner. The thickness direction of the rectifying element 4 is parallel or adapted to the air inlet direction, and the width direction of the rectifying element 4 is perpendicular to the air inlet direction or the thickness direction. As shown in FIG. 1, Figure 5 The row of strip plates 41 includes a rectifying plate slot 411, a rectifying retractable plate 412, and a spring damper 413. Figure 5 The rectifying retractable plate 412 and the spring damper 413 in FIG. 1 are in dashed lines to show the perspective effect. The rectifying plate slot 411 has a long and thin plate structure, and the long and thin plate structure is half-opened to form a long and thin slot, which accommodates the rectifying retractable plate 412. The spring damper 413 is filled between the rectifying plate slot 411 and the rectifying retractable plate 412 along the thickness direction. As shown in FIG. 2, Figure 6 The spring damper 413 is filled between the rectifying plate slot 411 and the rectifying retractable plate 412 along the width direction. Figure 6 The rectifying retractable plate 412 and the spring damper 413 in FIG. 2 are in dashed lines to show the perspective effect. The spring damper 413 is filled along the width direction, and the rectifying retractable plate 412 can absorb the wind force blown at a certain angle to the strip plate, and flexibly guide the wind to achieve the purpose of rectification. The column of strip plates 42 has the same structure of the spring damper 413 as the row of strip plates 41.

[0080] The rectifying element 4 in this embodiment can efficiently rectify the airflow and significantly reduce the turbulence degree of the airflow. When the wind pressure fluctuates, the rectifying retractable plate 412 can automatically retract (the amplitude is controlled between ±5 mm). If the wind blows at a certain angle to the plate, under the buffering effect of the rectifying retractable plate 412, the wind can be rectified to flow along the direction of the plate. For the traditional steel plate, the wind will be bounced back and flow downstream at a small angle. The spring damper 413 absorbs the fluctuating energy of the airflow to reduce the vibration frequency of the rectifying retractable plate 412, so as to prevent the row of strip plates 41 or the column of strip plates 42 from loosening or breaking.

[0081] Optionally, the bottom of the rectifier plate slot 411 is provided with a drain hole, which cooperates with the slope of the air duct to prevent condensate from accumulating and causing spring corrosion or coal powder caking. The surface of the row of strip plates 41 or the column of strip plates 42 can be optionally sprayed with a silicon carbide ceramic coating (thickness selected as 0.5 mm) to increase hardness and significantly reduce wear rate under high coal powder concentration conditions.

[0082] The installation process of the rectifying element 4 in the embodiment:

[0083] Confirm that the opening direction of the long and thin slot is the same as the airflow direction, and there is no burr or slag in the slot;

[0084] Pre-press the spring damping part 413, calculate the pre-tightening force according to the design wind speed;

[0085] After the rectifying telescopic plate 412 is inserted into the thin slot, manual sliding should not be stuck, and the gap between the top of the rectifying telescopic plate 412 and the top of the air duct is less than or equal to 5 mm.

[0086] The above embodiment is only one of the implementation manners capable of realizing the technical scheme of the present application, and the scope of the present application is not limited to the above embodiment, but also includes any changes, substitutions and other implementation manners easily thought of by those skilled in the art within the technical scope disclosed by the present application. Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A device for optimizing the measurement and distribution uniformity of inlet air volume in a coal mill, characterized in that, It includes a flow equalization element, a rectification element, and a flow guiding element. The flow equalization element, the rectification element, and the flow guiding element are all installed in the primary air duct at the inlet of the coal mill, and the three can be used individually or in combination. The direction of the flow equalization element or the rectification element is perpendicular to the flow direction of the inlet branch pipe. The direction of the flow guiding element is parallel to the flow direction of the inlet branch pipe.

2. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 1, characterized in that, The current equalization element is a porous plate structure with a thickness of 5mm-6mm.

3. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 1, characterized in that, The rectifier element is formed by alternating rows of strips and columns of strips.

4. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 1, characterized in that, The airflow guiding element is composed of multiple layers of arc plates adapted to the bends of the air duct.

5. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 3, characterized in that, The strips arranged in rows or columns are retractable.

6. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 5, characterized in that, The strips arranged in rows or columns are expandable and contractible along the width direction, and are provided with spring damping elements along the width direction.

7. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 5, characterized in that, The strips arranged in rows or columns are expandable and contractible along the thickness direction, and are provided with spring damping elements along the thickness direction.

8. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 7, characterized in that, A flow equalization element is installed 0.5 meters upstream of the air volume measuring element in the primary air duct at the inlet of the coal mill.

9. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 8, characterized in that, When the inlet air volume of the coal mill is one-third of the air volume of each coal mill in the unit, the porosity of the flow equalization element is 0.5-0.

7.

10. The device for optimizing the measurement and distribution uniformity of coal mill inlet air volume according to claim 8, characterized in that, When the inlet air volume of the coal mill is one-third of the middle value of the air volume of each coal mill in the unit, the porosity of the flow equalization element is 0.7-0.8.

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