CN115215111A - Anti-blocking coal breakage pipe square and round knot and design method thereof - Google Patents
Anti-blocking coal breakage pipe square and round knot and design method thereof Download PDFInfo
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- CN115215111A CN115215111A CN202210663447.1A CN202210663447A CN115215111A CN 115215111 A CN115215111 A CN 115215111A CN 202210663447 A CN202210663447 A CN 202210663447A CN 115215111 A CN115215111 A CN 115215111A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G65/00—Loading or unloading
- B65G65/30—Methods or devices for filling or emptying bunkers, hoppers, tanks, or like containers, of interest apart from their use in particular chemical or physical processes or their application in particular machines, e.g. not covered by a single other subclass
- B65G65/34—Emptying devices
- B65G65/40—Devices for emptying otherwise than from the top
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Abstract
The invention discloses an anti-blocking coal breakage pipe square-round knot and a design method thereof, and belongs to the field of coal-fired power station boiler pulverizing system equipment. The invention designs a square-round knot into a variable cross-section tube, one end of the variable cross-section tube is a square hole, the other end of the variable cross-section tube is a round hole, the cross-sectional area of the square hole is larger than that of the round hole, the center points of the square hole and the round hole are on the same straight line, and the side surface of the variable cross-section tube is formed by smoothly connecting an inclined plane with an inclined angle and an arc surface; the minimum diameter of the round hole is calculated by the cohesive force and the internal friction resistance of raw coal, and the minimum inclination angle of the inclined plane and the cambered surface is determined by the height of the coal dropping pipe and the diameter of the round hole. The invention can prevent the blockage of the raw coal in the design range at the square and round junctions, thereby not influencing the normal production of the unit.
Description
Technical Field
The invention relates to the field of coal-fired power plant boiler pulverizing system equipment, in particular to an anti-blocking coal breakage pipe square-round knot and a design method thereof.
Background
The square and round knot is a connecting pipe section between a coal feeder and a coal mill of a boiler pulverizing system, and once blockage occurs, the coal mill is broken, the coal feeder is tripped, the boiler load is changed in a large range, and even unplanned shutdown accidents occur.
The traditional square-round knot design only considers the coal flow conveying under the stable working condition, and the inner diameter is smaller. In the actual operation process, parameters such as weather conditions, raw coal granularity and water content change all the time, for example, when the water content of local raw coal is increased, the internal friction force and cohesive force among raw coal particles are greatly increased, so that the raw coal at the square and round junction is accumulated and blocked. On the other hand, the instability of the operation condition requires that the square-round junction has strong anti-interference capability, such as: when the coal feeder is unstable in operation and the instantaneous coal flow fluctuation is large, the square-round knot is blocked, so that the anti-shearing force of the raw coal in the square-round knot needs to be checked and calculated, and the coal blockage can automatically collapse under any working condition.
In summary, the conventional square-round junction design has drawbacks and needs to be improved.
Disclosure of Invention
In order to make up for the defects of the prior art, the invention provides an anti-blocking coal breakage pipe square-round knot and a design method thereof, so that the situation that raw coal in a design range is blocked at the square-round knot is prevented.
Therefore, the technical scheme adopted by the invention is as follows: a design method for an anti-blocking coal dropping pipe square-round knot is characterized in that the square-round knot is designed into a variable-section pipe, one end of the variable-section pipe is a square hole, the other end of the variable-section pipe is a round hole, the sectional area of the square hole is larger than that of the round hole, the central points of the square hole and the round hole are on the same straight line, and the side surface of the variable-section pipe is formed by smoothly connecting an inclined plane with an inclined angle and an arc surface;
the minimum diameter of the round hole is calculated by the cohesive force and the internal friction resistance of raw coal, and the minimum inclination angle of the inclined plane and the cambered surface is determined by the height of the coal dropping pipe and the diameter of the round hole.
Further, the shear strength τ of the raw coal particles is calculated by using the stacking characteristic parameters thereof as shown in formula (1).
τ＝σ·tanφ+C (1)
In the formula: σ · tan Φ is the internal friction term, kPa; c is cohesion term, kPa. Sigma is the normal pressure of the shearing surface, kPa; tan phi is the coefficient of internal friction resistance; phi is the internal friction angle, degree (°);
further, the shear stress of the ideal cylindrical piled raw coal is subjected to stress analysis, and the radius r of the round hole of the square-round knot can be calculated according to the formula (2).
τ·2πr·h＝ρ·πr 2 ·h·g (2)
In the formula: h is the height of ideal cylindrical piled raw coal, m; g is the acceleration of gravity, m/s 2 (ii) a Rho is the bulk density of the design raw coal, kg/m 3 ；
Obviously, the normal pressure σ of the shearing surface at this time is 0, and therefore the design value of the radius of the circular hole should be larger than the calculated value of r in the equation (2).
Furthermore, since the sectional area of the square hole is larger than that of the round hole, a tapered section exists at the square-round junction, the normal pressure σ of the shearing surface is larger than 0, and after the radius r of the round hole is selected, the height H of the square-round junction needs to be checked and calculated, so that the height of the square-round junction formed by the formula (2) is the longest height. If the height H of the square-round junction is increased, the radius r of the round hole is further increased until the formula (2) is satisfied.
As a preferred scheme, the size and the side surface of the normal pressure sigma of the shearing surface are related to the inclination angle theta of the central axis of the square-round junction, the theta is 0-90 degrees, and the normal pressure sigma of the cylindrical shearing surface can be obtained by carrying out stress analysis on the square-round junction according to a calculation formula (3).
Further, the larger the square-round knot height H is, the smaller the inclination angle θ is, and the larger the normal pressure σ is, and in order to prevent the instantaneous coal flow from being excessively large, the whole square-round knot is clogged in a short time, and the square-round knot height H is maximized as much as possible.
Further, obviously, the inclination angle theta between the inclined plane of the long side of the square hole and the central axis of the square-round junction is the minimum, the normal pressure sigma has the maximum value, the surface is taken as a checking calculation surface, the equivalent frustum pyramid method is adopted to calculate V, and finally the height H of the square-round junction is calculated.
Wherein V is the equivalent prism volume:
in the formula: and a and b are the width and length of the square hole of the square-round knot, and m.
Further, substituting equations (3) and (4) into equations (1) and (2) can obtain a calculation formula of the square-round junction height H, and the calculation process is as follows, and the result is shown in equation (5):
wherein:
simplifying to obtain:
the invention has the following beneficial effects:
1. can ensure that the square-round knot can never cause coal blockage within the design range of raw coal parameters.
2. The design method is also suitable for the design problem of the square-round knot involved in other feeding systems, and has wide application range.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic perspective view of a square and round knot of an anti-blocking coal dropping pipe according to the present invention;
FIG. 2 is a top view of the square and round knots of the anti-clogging coal dropping pipe of the present invention;
FIG. 3 is a front view of a square and round knot of the anti-blocking coal dropping pipe of the present invention;
FIG. 4 is a left side view of the square and round knot of the anti-clogging coal dropping pipe of the present invention.
Detailed Description
The present invention will be described in detail below with reference to examples to provide those skilled in the art with a better understanding of the present invention, but the present invention is not limited to the following examples.
Unless otherwise defined, terms (including technical and scientific terms) used herein should be construed to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
A design method for an anti-blocking coal dropping pipe square-round knot is characterized in that the square-round knot is designed into a variable cross-section pipe, a schematic diagram is shown in figures 1-4, one end of the pipe is a square hole (width a and length b), the other end of the pipe is a round hole (diameter d), the center points of the square hole and the round hole are on the same straight line, and the side surface of the pipe is formed by smoothly connecting inclined planes 2 and 3 with an inclined angle and an arc surface 1. The minimum diameter of the circular hole is obtained by calculating the cohesive force and the internal friction resistance of raw coal, and the minimum inclination angle theta of the inclined planes 2 and 3 and the cambered surface 1 is determined by the height H of the coal dropping pipe and the diameter d of the circular hole.
The shear strength tau of the raw coal particles is calculated by using the stacking characteristic parameters of the raw coal particles as shown in the formula (1).
τ＝σ·tanφ+C (1)
In the formula: σ · tan Φ is the internal friction term, kPa; c is cohesion term, kPa. Sigma is the normal pressure of the shearing surface, kPa; tan phi is an internal friction resistance coefficient; phi is the internal friction angle, degree (°);
and (3) carrying out stress analysis on the shearing stress of the ideal cylindrical piled raw coal, and calculating the radius r of the round hole of the square-round knot according to the formula (2).
τ·2πr·h＝ρ·πr 2 ·h·g (2)
In the formula: h is the height of ideal cylindrical piled raw coal, m; g is gravity acceleration, m/s 2 (ii) a Rho is the bulk density of the design raw coal, kg/m 3 ；
Obviously, the normal pressure σ of the shearing surface at this time is 0, and therefore the design value of the radius of the circular hole should be larger than the calculated value of r in the equation (2).
Because the sectional area of the square hole is larger than that of the round hole, a tapered section exists at the square-round junction, the normal pressure sigma of the shearing surface is larger than 0, and after the radius r of the round hole is selected, the height H of the square-round junction needs to be checked and calculated, so that the height of the square-round junction formed by the formula (2) is the longest height. If the height H of the square-round junction is increased, the radius r of the round hole is further increased until the formula (2) is satisfied.
The size and the side surface of the normal pressure sigma of the shearing surface are related to the inclination angle theta of the central axis of the square-round junction, the theta is 0-90 degrees, and the normal pressure sigma of the cylindrical shearing surface can be obtained by carrying out stress analysis on the square-round junction according to a calculation formula (3).
The larger the square-round knot height H is, the smaller the inclination angle theta is, the larger the normal pressure sigma is, and in order to prevent the instantaneous coal from flowing too much and block the whole square-round knot in a short time, the height H of the square-round knot is the largest value as possible.
Obviously, the inclination angle theta between the long-side inclined plane of the square hole and the central axis of the square-round junction is minimum, the normal pressure sigma has the maximum value, the plane is taken as a checking calculation plane, the V is calculated by adopting an equivalent frustum method, and finally the height H of the square-round junction is calculated.
Wherein V is the equivalent prism volume:
in the formula: a. and b is the width and length of the square hole of the square-round knot, m.
Substituting the formulas (3) and (4) into the formulas (1) and (2) can obtain a calculation formula of the square-round knot height H, which is shown in a formula (5). The derivation process is (4) to (3), then (3) to (1), and finally (1) to (2), the calculation process is as follows, and the result is as shown in formula (5):
wherein:
(this can be directly obtained by FIG. 4)
Simplifying to obtain:
the above-described embodiments are merely representative of general embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (7)
1. A design method for an anti-blocking coal dropping pipe square-round knot is characterized in that the square-round knot is designed into a variable-section pipe, one end of the variable-section pipe is a square hole, the other end of the variable-section pipe is a round hole, the sectional area of the square hole is larger than that of the round hole, the central points of the square hole and the round hole are on the same straight line, and the side surface of the variable-section pipe is formed by smoothly connecting an inclined plane with an inclined angle and an arc surface;
the minimum diameter of the round hole is calculated by the cohesive force and the internal friction resistance of raw coal, and the minimum inclination angle of the inclined plane and the cambered surface is determined by the height of the coal dropping pipe and the diameter of the round hole.
2. The method for designing the anti-blocking coal breakage pipe square-round knot according to claim 1, wherein the shear strength τ is calculated by using the stacking characteristic parameter of raw coal particles, as shown in formula (1):
τ＝σ·tanφ+C (1)
in the formula: σ · tan Φ is the internal frictional resistance term in kPa; c is cohesive force term with unit of kPa; sigma is the normal pressure of the shearing surface, and the unit is kPa; tan phi is the coefficient of internal friction resistance; phi is the internal friction angle, and the unit is degree;
and (3) carrying out stress analysis on the shear stress of the ideal cylindrical piled raw coal, and calculating the radius r of the round hole of the square-round knot according to the formula (2):
τ·2πr·h＝ρ·πr 2 ·h·g (2)
in the formula: h is the height of ideal cylindrical piled raw coal and the unit is m; g is the acceleration of gravity in m/s 2 (ii) a Rho is the bulk density of the design raw coal and has the unit of kg/m 3 ；
At this time, the normal pressure σ of the shearing surface is 0, and therefore the design value of the radius of the circular hole is larger than the calculated value of r in the equation (2).
3. The design method of the anti-blocking coal breakage pipe square-round knot as claimed in claim 2, wherein the square-round knot has a tapered section, the normal pressure sigma of the shearing surface is greater than 0, and after the radius r of the round hole is selected, the height H of the square-round knot needs to be checked, so that the height of the square-round knot formed by the formula (2) is the longest height; if the height H of the square-round junction is increased, the radius r of the round hole is further increased until the formula (2) is satisfied.
4. The design method of the anti-blocking coal breakage pipe square-round knot as claimed in claim 3, wherein the size and the side surface of the normal pressure sigma of the shearing surface are related to the inclination angle theta of the central axis of the square-round knot, theta is 0-90 degrees, and the normal pressure sigma of the cylindrical shearing surface is obtained by performing stress analysis on the square-round knot according to the calculation formula (3):
the larger the height H of the square-round knot is, the smaller the inclination angle theta is, the larger the normal pressure sigma is, in order to prevent the instantaneous coal from flowing too much, the whole square-round knot is blocked in a short time, the height H of the square-round knot is the largest value as far as possible, obviously, the inclination angle theta between the long-side inclined plane of the square hole and the central axis of the square-round knot is the smallest, the maximum value exists in the normal pressure sigma, the surface is taken as a checking calculation surface, the equivalent prismatic table volume V is calculated by adopting an equivalent prismatic table method, and finally, the height H of the square-round knot is calculated.
5. The design method of the square-round knot of the anti-blocking coal drop pipe as recited in claim 4, wherein the equivalent frustum volume V is:
in the formula: a. and b is the width and length of the square hole of the square-round knot, m.
6. The design method of the anti-clogging coal breakage pipe square-round knot as defined in claim 5, wherein the formula (3) and the formula (4) are substituted into the formula (1) and the formula (2) to obtain a calculation formula of the square-round knot height H, and the calculation process is as follows, and the result is as shown in the formula (5):
wherein：
Simplifying to obtain:
7. the anti-blocking coal breakage pipe square-round knot obtained by the design method of any one of claims 1 to 6.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3716047A1 (en) * | 1987-05-14 | 1988-12-01 | Behn Maschf | Method and device for operating a filling apparatus for dust-like or granular material |
| CN202429562U (en) * | 2011-12-13 | 2012-09-12 | 中国轻工业长沙工程有限公司 | Non-blockage deformed coal bunker |
| CN204979890U (en) * | 2015-09-25 | 2016-01-20 | 安徽新力电业科技咨询有限责任公司 | Raw coal feed feed bin |
| CN205708941U (en) * | 2016-04-26 | 2016-11-23 | 中国电力工程顾问集团中南电力设计院有限公司 | Double-deck split anti-blocking raw coal bucket |
| EP3239609A1 (en) * | 2016-04-29 | 2017-11-01 | The Babcock & Wilcox Company | Simplified submerged chain conveyor for bottom ash conversions |
| CN211971083U (en) * | 2020-04-14 | 2020-11-20 | 李兴民 | Novel concrete unloading mechanism |
-
2022
- 2022-06-13 CN CN202210663447.1A patent/CN115215111B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3716047A1 (en) * | 1987-05-14 | 1988-12-01 | Behn Maschf | Method and device for operating a filling apparatus for dust-like or granular material |
| CN202429562U (en) * | 2011-12-13 | 2012-09-12 | 中国轻工业长沙工程有限公司 | Non-blockage deformed coal bunker |
| CN204979890U (en) * | 2015-09-25 | 2016-01-20 | 安徽新力电业科技咨询有限责任公司 | Raw coal feed feed bin |
| CN205708941U (en) * | 2016-04-26 | 2016-11-23 | 中国电力工程顾问集团中南电力设计院有限公司 | Double-deck split anti-blocking raw coal bucket |
| EP3239609A1 (en) * | 2016-04-29 | 2017-11-01 | The Babcock & Wilcox Company | Simplified submerged chain conveyor for bottom ash conversions |
| CN211971083U (en) * | 2020-04-14 | 2020-11-20 | 李兴民 | Novel concrete unloading mechanism |
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