An air volume measuring device for a swirl burner and a swirl burner

Abstract

The present invention relates to an air volume measuring device for a swirl burner, which includes a first ring body with holes, a second ring body, and a pressure measuring component for measuring the wind pressure inside the measuring holes. The first ring body is sleeved outside the second ring body, and an air duct is formed between the first ring body and the second ring body. The air duct includes a first section and a second section. The first section of the air duct is a straight section, and the diameter of the second section of the air duct forms a change from large to small and then to large; a swirl burner includes a secondary air inlet pipe and an air volume measuring device. The secondary air inlet pipe is an annular pipe, the second ring body is connected to the outer side surface of the secondary air inner pipe, and the first ring body is connected to the inner side surface of the secondary air outer pipe. The shape of the present invention matches the secondary air inlet pipe of the swirl burner, which is convenient for the installation of the device, has low manufacturing and maintenance costs, and is convenient for large-scale implementation; the structure of a Venturi tube is provided, which can accurately measure the secondary air volume of the swirl burner and realize long-term reliable, stable, and accurate measurement of the secondary air volume of the swirl burner.

Description

Technical Field

[0001] The present invention belongs to the field of combustion boilers, and particularly relates to an air volume measuring device for a swirl burner and a swirl burner. Background Art

[0002] Opposed fired boilers account for a large proportion in domestic large-scale coal-fired units due to characteristics such as easier implementation of large-scale due to the burner layout. However, during actual operation, they often face problems such as oxygen-deficient combustion of burners near the side wall, high CO content in flue gas, and severe high-temperature corrosion on both side walls. Especially after the implementation of more stringent ultra-clean emission standards, the above problems are more prominent. Ensuring uniform combustion of burners on the same layer is crucial for opposed fired boilers. The most core is how to accurately measure the secondary air volume of each burner. However, limited by the structural characteristics of the swirl burner, it is very difficult to measure the air volume of the secondary air of the burner. Therefore, currently, the swirl burners of opposed fired boilers in China basically do not install on-line air volume measuring devices. Debugging personnel often can only be forced to adjust the inner and outer secondary air baffles of the corresponding burners by the flue gas composition distribution in the cross-section of the tail flue, and this method has a large error. For operating personnel, due to the lack of on-line air volume measuring equipment, accurate adjustment of the air volume is even more out of the question.

[0003] Existing on-line air volume measuring devices for swirl burners are mainly arc-shaped whistle tubes and multi-point backrest tubes. Since the secondary air contains certain dust and other impurities, the above-mentioned air measuring devices are extremely prone to blockage problems during use, which have a great impact on air volume measurement and seriously affect the accuracy of air volume measurement. The problem that the boiler cannot achieve uniform combustion due to the inability to accurately measure the secondary air volume of the burner still cannot be solved.

[0004] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide an air volume measuring device for a swirl burner, which is used to accurately measure the air volume of the swirl burner.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] An air volume measuring device for a swirl burner includes a first ring body, a second ring body and a pressure measuring component. Holes are formed on the first ring body and / or the second ring body. The pressure measuring component is used to measure the pressure of the air in the holes. An inner convex part protruding from the inner peripheral surface of the first ring body and / or an outer convex part protruding from the outer peripheral surface of the second ring body are formed.

[0008] In the use state, the first ring body is sleeved outside the second ring body, and an air duct is formed between the inner peripheral surface of the first ring body and the outer peripheral surface of the second ring body. The air duct includes a first section and a second section. The first section of the air duct is a straight section. The inner convex part of the first ring body and / or the outer convex part of the second ring body causes the diameter of the second section of the air duct to change from large to small and then to large. The holes include first holes opened on the first ring body and / or the second ring body located in the first section of the air duct, and second holes opened on the first ring body and / or the second ring body located in the second section of the air duct.

[0009] Preferably, the holes are opened on both the first ring body and the second ring body. In the use state, the holes on the first ring body are distributed on its upper half circumferential surface, and the holes on the second ring body are distributed on its lower half circumferential surface.

[0010] More preferably, the first holes and the second holes are opened on both the first ring body and the second ring body.

[0011] Even more preferably, a plurality of the first holes and a plurality of the second holes are opened. In the use state, the angles between adjacent two of the first holes on the projection plane in the radial direction of the first ring body and the second ring body are equal; the angles between adjacent two of the second holes on the projection plane in the radial direction of the first ring body and the second ring body are equal.

[0012] Even more preferably, one first hole and one second hole on the first ring body form a group, and the first hole and the second hole in this group are distributed along the axial direction of the first ring body; one first hole and one second hole on the second ring body form a group, and the first hole and the second hole in this group are distributed along the axial direction of the second ring body.

[0013] Even more preferably, the device further includes branch pipes and a main pipe. The branch pipes are communicated with the holes, and the branch pipes communicating with the first holes are all communicated with one main pipe; the branch pipes communicating with the second holes are all communicated with the other main pipe.

[0014] Even further preferably, a plurality of the first holes and a plurality of the second holes are opened. A plurality of annular pipes are respectively opened around the axis in the first ring body and around the axis in the second ring body. The plurality of first holes of the first ring body, the plurality of second holes of the first ring body, the plurality of first holes of the second ring body, and the plurality of second holes of the second ring body are respectively communicated with one annular pipe, and a plurality of branch pipes are provided. One annular pipe is communicated with one branch pipe.

[0015] Even further preferably, part of the branch pipes is located inside the first ring body and the second ring body.

[0016] Preferably, in the use state, the first ring body and the second ring body are coaxially arranged; both the first ring body and the second ring body are circular rings.

[0017] Preferably, the second hole is opened on the first ring body and / or the second ring body at the smallest diameter position of the second section of the air duct.

[0018] Preferably, the inner convex part of the first ring body and the outer convex part of the second ring body have the same shape.

[0019] More preferably, in the use state, the minimum diameter of the second section of the air duct is 1 / 3 of the diameter of the first section of the air duct, and the aperture of the second hole is 1 / 3 of the diameter of the first section of the air duct.

[0020] Even more preferably, both the inner convex part and the outer convex part include a first surface, a second surface, and a third surface connected in sequence. The first surface of the inner convex part is connected to the inner surface of the first section of the first ring body. The first surface of the inner convex part is an inclined surface. The second surface of the inner convex part is parallel to the axis of the first ring body. The third surface of the inner convex part is an inclined surface. The first surface of the outer convex part is connected to the outer surface of the first section of the second ring body. The first surface of the outer convex part is an inclined surface. The second surface of the outer convex part is parallel to the axis of the second ring body. The third surface of the outer convex part is an inclined surface.

[0021] Still more preferably, the included angle between the first surface and the second surface of the inner convex part is 20 - 22°, and the included angle between the third surface and the second surface of the inner convex part is 7 - 15°; the included angle between the first surface and the second surface of the outer convex part is 20 - 22°, and the included angle between the third surface and the second surface of the outer convex part is 7 - 15°.

[0022] The object of the present invention is to provide a swirl burner for achieving uniform combustion.

[0023] To achieve the above object, the technical solution adopted by the present invention is:

[0024] A swirl burner includes a secondary air inlet pipe and also includes the air volume measuring device for the swirl burner. The secondary air inlet pipe is an annular pipe and includes a secondary air inner pipe and a secondary air outer pipe sleeved outside the secondary air inner pipe. The second ring body is connected to the outer side surface of the secondary air inner pipe, and the first ring body is connected to the inner side surface of the secondary air outer pipe.

[0025] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0026] The shape of the present invention matches the secondary air inlet pipe of the swirl burner, facilitating the installation of the device. At the same time, the manufacturing and maintenance costs are relatively low, making it convenient for large-scale implementation. It is provided with a Venturi tube structure, which can accurately measure the secondary air volume of the swirl burner, solving the problem that there is no effective air volume measurement device for the secondary air volume of the swirl burner. It overcomes the deficiencies of the existing air volume measurement devices, such as blockage and inability to accurately measure for a long time, and realizes long-term reliable, stable and accurate measurement of the secondary air volume of the swirl burner, laying a solid foundation for the uniform combustion of the opposed firing boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Appendix Figure 1 is a schematic structural diagram of the air volume measurement device in this embodiment;

[0028] Appendix Figure 2 is a schematic structural diagram of the air volume measurement device when it is arranged in the secondary air inlet pipe in this embodiment;

[0029] Appendix Figure 3 is an axial sectional view of the air volume measurement device when it is arranged in the secondary air inlet pipe in this embodiment.

[0030] In the above drawings: 11, the first ring body; 12, the second ring body; 21, the inner convex part; 22, the outer convex part; 23, the first surface; 22, the second surface; 25, the third surface; 26, the air duct; 3, the first hole; 4, the second hole; 5, the branch pipe; 6, the annular pipe; 7, the secondary air inner pipe; 8, the secondary air outer pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] As Figure 1 , 3 shown, a device for measuring the air volume of a swirl burner includes a first ring body 11, a second ring body 12 and a pressure measuring component. The first ring body 11 and the second ring body 12 are both provided with holes, and the pressure measuring component is used to measure the pressure of the air in the holes.

[0035] Both the first ring body 11 and the second ring body 12 are circular rings and have the same length. An inner convex portion 21 protruding from its surface is formed on the inner peripheral surface of the first ring body 11, and an outer convex portion 22 protruding from its surface is formed on the outer peripheral surface of the second ring body 12. The inner convex portion 21 of the first ring body 11 and the outer convex portion 22 of the second ring body 12 have the same shape. In this embodiment, the materials of the first ring body 11 and the second ring body 12 are heat-resistant alloy steel ZG 30 Cr 20 Ni 14 , which has strong high-temperature resistance and wear resistance, greatly extending the service life. In the use state, the first ring body 11 and the second ring body 12 are coaxially arranged, and an air duct 26 is formed between the inner peripheral surface of the first ring body 11 and the outer peripheral surface of the second ring body 12. The air duct 26 includes a first section and a second section. The first section of the air duct 26 is a straight section, and the second section of the air duct 26 is formed between the inner convex portion 21 of the first ring body 11 and the outer convex portion 22 of the second ring body 12. Moreover, the inner convex portion 21 and the outer convex portion 22 are symmetrically arranged, so that the diameter of the second section of the air duct 26 changes from large to small and then to large. In the use state, the air flows from the first section of the air duct 26 to its second section. This embodiment can be used as the structure of a Venturi tube to measure the air volume.

[0036] The inner convex part 21 of the first annular body 11 and the outer convex part 22 of the second annular body 12 both include a first surface 23, a second surface 24, and a third surface 25 that are sequentially connected. The first surface 23 of the inner convex part 21 is connected to the first-section inner surface of the first annular body 11. The first surface 23 of the inner convex part 21 is an inclined surface. The second surface 24 of the inner convex part 21 is parallel to the axis of the first annular body 11. The third surface 25 of the inner convex part 21 is an inclined surface. The first surface 23 of the outer convex part 22 is connected to the first-section outer surface of the second annular body 12. The first surface 23 of the outer convex part 22 is an inclined surface. The second surface 24 of the outer convex part 22 is parallel to the axis of the second annular body 12. The third surface 25 of the outer convex part 22 is an inclined surface. In the working state, the wind flows through the first surface 23, the second surface 24, and the third surface 25 in sequence. Along the wind flow direction, the diameter of the first section of the air duct 26 is L, and the cross-sectional area is S1. The first surfaces 23 of the inner convex part 21 and the outer convex part 22 gradually approach to form a contraction section of the second section of the air duct 26. The second surfaces 24 of the inner convex part 21 and the outer convex part 22 are parallel to each other to form a throat straight pipe section of the second section of the air duct 26. The throat straight pipe section of the second section of the air duct 26 is the narrowest part of the air duct 26, and its length and diameter are both 1 / 3L, and the cross-sectional area is S2. The third surfaces 25 of the inner convex part 21 and the outer convex part 22 gradually move away from each other to form a diffusion section of the second section of the air duct 26. The angle between the first surface 23 and the second surface 24 of the inner convex part 21 is the same as the angle between the first surface 23 and the second surface 24 of the outer convex part 22, and the angle range is between 20 - 22°. The angle between the second surface 24 and the third surface 25 of the inner convex part 21 is the same as the angle between the second surface 24 and the third surface 25 of the outer convex part 22, and the angle range is between 7 - 15°. The specific size of the device can be flexibly adjusted according to the actual installation environment.

[0037] The holes include first holes 3 opened on the first annular body 11 and the second annular body 12 located in the first section of the air duct 26, and second holes 4 opened on the first annular body 11 and the second annular body 12 located in the second section of the air duct 26. A plurality of first holes 3 and a plurality of second holes 4 are opened on the first annular body 11. A plurality of first holes 3 and a plurality of second holes 4 are opened on the second annular body 12. The first holes 3 are located in the first section of the air duct 26, and the second holes 4 are located in the throat straight pipe section of the second section of the air duct 26. The diameter of the second holes 4 is equal to the length of the throat straight pipe section where they are located, and is also 1 / 3L. One first hole 3 and one second hole 4 located on the first annular body 11 form a group. The first hole 3 and the second hole 4 in this group are distributed along the axial direction of the first annular body 11. One first hole 3 and one second hole 4 located on the second annular body 12 form a group. The first hole 3 and the second hole 4 in this group are distributed along the axial direction of the second annular body 12. What is measured for the first hole 3 is the positive pressure when the wind flows through the device, and what is measured for the second hole 4 is the negative pressure when the wind flows through the device. Therefore, the air duct 26 of the device can form a Venturi structure. This structure has small pressure loss, good dust prevention effect, no strict requirements for the straight pipe section, and a high dynamic pressure amplification multiple and is more accurate. The multi-section uniform and stable measurement can be realized by using the Venturi structure.

[0038] The first holes 3 and the second holes 4 on the first annular body are located in two opposite semi - rings relative to the first holes 3 and the second holes 4 on the second annular body. In the use state, the axial directions of the first annular body 11 and the second annular body 12 are horizontally arranged. The first holes 3 and the second holes 4 on the first annular body 11 are both distributed on the inner circumferential surface of its upper semi - ring, and the holes on the second annular body 12 are distributed on the outer circumferential surface of its lower semi - ring. Then the holes are all opened upwards, further achieving the purpose of effectively preventing ash and blockage, so as to realize the long - term reliable, stable and accurate measurement of the secondary air measurement device of the swirl burner. In the use state, the angles between adjacent two first holes 3 on the projection planes in the radial direction of the first annular body 11 and the second annular body 12 are equal, that is, they are equally distributed on the cross - section of the air flow direction. The angles between adjacent two second holes 4 on the projection planes in the radial direction of the first annular body 11 and the second annular body 12 are equal, that is, they are equally distributed on the cross - section of the air flow direction. In this embodiment, six first holes 3 are provided, with three on each of the first annular body 11 and the second annular body 12. Six second holes 4 are provided, with three on each of the first annular body 11 and the second annular body 12.

[0039] The device further includes a plurality of branch pipes 5, a plurality of annular pipes 6, and two main pipes. The annular pipes 6 are arranged inside the first annular body 11 and the second annular body 12 and are respectively arranged around the axis of the first annular body 11 and the axis of the second annular body 12. A plurality of first holes 3 on the first annular body 11 are all communicated with one annular pipe 6, a plurality of second holes 4 on the first annular body 11 are all communicated with one annular pipe 6, a plurality of first holes 3 on the second annular body 12 are all communicated with one annular pipe 6, and a plurality of second holes 4 on the second annular body 12 are all communicated with one annular pipe 6, that is, four annular pipes 6 are provided. Part of the branch pipes 5 are located inside the first annular body 11 and the second annular body 12, and the material is made of stainless steel. The branch pipes 5 are directly led out along the axial direction. In the use state, they do not occupy the space inside the burner body, are convenient for installation, and are convenient for large - scale installation of the device. One annular pipe 6 is communicated with one branch pipe 5, that is, four branch pipes 5 are provided. The branch pipes 5 extend out of the first annular body 11 and the second annular body 12 and are communicated with the main pipes. The branch pipes 5 communicating with the first holes 3 are all communicated with one main pipe, and the branch pipes 5 communicating with the second holes 4 are all communicated with the other main pipe. The pressure - measuring device is connected to the two main pipes. The pressure - measuring device can adopt a differential pressure transmitter, a micro - pressure gauge or a U - shaped manometer. The pressure - measuring device can measure the pressure P1 of the main pipe communicating with the first holes 3 and the pressure P2 of the main pipe communicating with the second holes 4.

[0040] Such as Figure 2 、 3As shown in the figure, a swirl burner includes a secondary air inlet pipe. The secondary air inlet pipe is an annular pipe and includes a secondary air inner pipe 7 and a secondary air outer pipe 8 sleeved outside the secondary air inner pipe 7. The swirl burner further includes the above-mentioned air volume measuring device for the swirl burner. According to the size of the annular secondary air inlet pipe of the swirl burner, a suitable air volume measuring device is manufactured, and the air volume measuring device is placed into the annular secondary air inlet pipe of the swirl burner and fixed to the secondary air inlet pipe of the swirl burner by welding. The outer peripheral surface of the first ring body 11 is connected to the inner side surface of the secondary air outer pipe 8, the inner peripheral surface of the second ring body 12 is connected to the outer side surface of the secondary air inner pipe 7, and the branch pipe 5 extends outward from the air inlet side.

[0041] The working principle of this embodiment is specifically described as follows:

[0042] The air volume measuring device is horizontally installed in the secondary air inlet pipe. The cross-sectional area of the first section of the air duct 26 is measured as S1, the cross-sectional area of the throat straight pipe section of the second section is measured as S2, and the pressure P1 of the main pipe communicating with the first hole 3 and the pressure P2 of the main pipe communicating with the second hole 4 are obtained, so as to obtain the pressure difference (P1 - P2) of the air flow in the device. Then, through Bernoulli's theorem, the secondary air flow velocity in the annular secondary air inlet pipe of the swirl burner can be calculated, and further the flow rate can be calculated.

[0043] According to Bernoulli's equation, Equation (1): ;

[0044] In the formula, P is the pressure of a certain point in the secondary air, v is the flow velocity of this point in the secondary air, ρ is the fluid density, g is the acceleration due to gravity, h is the height of this point in the secondary air, and C is a constant.

[0045] For this annular Venturi air volume measuring device, because the axis is horizontally arranged during use and the height of the first section and the height of the throat straight pipe section of the second section are the same, therefore, Bernoulli's equation of Equation (1) is transformed into:

[0046] Equation (2): ;

[0047] In the formula, v1 is the flow velocity of the secondary air flowing through the first hole 3, and v2 is the flow velocity of the secondary air flowing through the second hole 4.

[0048] Also, because the volume of the secondary air flowing through in the same time is the same, Equation (3) can be obtained: .

[0049] Therefore, according to Equation (2) and Equation (3), the secondary air flow velocity at the first section (i.e., the inlet end) of the air duct 26 can be obtained as:

[0050] Equation (4): .

[0051] Then, the mass flow rate Q of the secondary air inlet pipe of the swirl burner can be calculated by Equation (V).

[0052] Equation (V): 。

[0053] Solve the long-existing problem that there is no effective air volume measuring device for the secondary air volume of the swirl burner, overcome the deficiencies of the existing device such as blockage and inability to accurately measure for a long time, realize the long-term reliable, stable and accurate measurement of the secondary air volume of the swirl burner, and at the same time its application lays a solid foundation for the uniform combustion of the opposed firing boiler.

[0054] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. An air volume measuring device for a swirl burner, characterized in that: It includes a first annular body, a second annular body and a pressure measuring component. The first annular body and the second annular body are provided with holes. The pressure measuring component is used to measure the pressure of the air in the holes. An inner convex part protruding from it is formed on the inner circumferential surface of the first annular body, and an outer convex part protruding from it is formed on the outer circumferential surface of the second annular body. The device further includes a branch pipe and a main pipe. The branch pipe is communicated with the hole. In the use state, the first annular body is sleeved outside the second annular body. An air duct is formed between the inner circumferential surface of the first annular body and the outer circumferential surface of the second annular body. The air duct includes a first section and a second section. The first section of the air duct is a straight section. The inner convex part of the first annular body and the outer convex part of the second annular body cause the diameter of the second section of the air duct to change from large to small and then to large. The holes include first holes opened on the first annular body and the second annular body located in the first section of the air duct, and second holes opened on the first annular body and the second annular body located in the second section of the air duct. One first hole and one second hole on the first annular body form a group. The first hole and the second hole in this group are distributed along the axial direction of the first annular body; one first hole and one second hole on the second annular body form a group. The first hole and the second hole in this group are distributed along the axial direction of the second annular body. The branch pipes communicating with the first holes are all communicated with one main pipe; the branch pipes communicating with the second holes are all communicated with the other main pipe. A plurality of first holes and second holes are provided. A plurality of annular pipes are respectively opened in the first annular body around its axis and in the second annular body around its axis. The plurality of first holes of the first annular body, the plurality of second holes of the first annular body, the plurality of first holes of the second annular body, and the plurality of second holes of the second annular body are respectively communicated with one annular pipe. A plurality of branch pipes are provided. One annular pipe is communicated with one branch pipe.

2. The air volume measuring device for a swirl burner according to claim 1, characterized in that: In the use state, the holes on the first annular body are distributed on its upper half circumferential surface, and the holes on the second annular body are distributed on its lower half circumferential surface.

3. The air volume measuring device for a swirl burner according to claim 1, wherein: In the use state, the included angles of the projections of two adjacent first holes on the radial projection planes of the first annular body and the second annular body are equal; the included angles of the projections of two adjacent second holes on the radial projection planes of the first annular body and the second annular body are equal.

4. The air volume measuring device for a swirl burner according to claim 1, characterized in that: In the use state, the first annular body and the second annular body are coaxially arranged; both the first annular body and the second annular body are circular rings.

5. The air volume measuring device for a cyclone burner according to claim 1, characterized in that: The shapes of the inner convex part of the first annular body and the outer convex part of the second annular body are the same.

6. A swirl burner, comprising a secondary air inlet duct, characterized in that It further includes the air volume measuring device for a swirl burner according to any one of claims 1-5. The secondary air inlet pipe is an annular pipe and includes a secondary air inner pipe and a secondary air outer pipe sleeved outside the secondary air inner pipe. The second annular body is connected to the outer side surface of the secondary air inner pipe, and the first annular body is connected to the inner side surface of the secondary air outer pipe.

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