A double-suction centrifugal fire pump with low cavitation performance

Abstract

The present invention provides a double-suction centrifugal fire pump with low cavitation performance. A guide cone is installed in the middle of the inner wall of the volute. The guide cone is formed by the intersection of a first guide cone plane and a second guide cone plane. An inlet turbulence device with a fish skeleton structure is arranged on the outer wall of the volute. The inlet turbulence device is located in the flow channel of the inlet section of the shell. The inlet turbulence device includes a plurality of turbulence guide vanes. The turbulence guide vanes are in an arc plate structure. The arc length of the turbulence guide vanes gradually increases along the water flow direction. A plurality of auxiliary jet holes are symmetrically arranged on the wall surface of the volute near the flow channel side of the inlet section of the shell. The blade booster part is in a pointed angle structure. The pointed angle of the blade booster part and the pointed angle of the guide cone are staggered in the axial direction. Due to the improvement of the fire pump structure, the hump is eliminated, cavitation is reduced, stability is good, vibration is low, reliability is high, and the working performance and operation efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of fluid machinery, and in particular to a double-suction centrifugal fire pump with low cavitation performance. Background Art

[0002] As an important safety equipment, fire pumps play a role in ensuring safety in flammable and explosive dangerous places such as petrochemical and coal chemical industries. When a fire occurs, they can be started in time to extinguish the fire and carry out disaster relief, protect life and property safety, and reduce fire losses. The hump on the performance curve of the fire pump is quite unfavorable to the operation of the pump. The hump can easily cause the water pump to overload and vibrate the pipeline, or cause the flow rate to be sometimes small and sometimes large, high cavitation, and unable to operate stably. This will affect the normal delivery of the fire pump, and sometimes even affect normal production and bring safety hazards.

[0003] The prior art CN220551287U discloses a low-vibration impeller structure for a single-stage fire pump, which is located in the pump body and includes: a back blade, a rear cover plate with a gradual change in the outlet part, and a front cover plate with an extended outlet part. The back blade and the impeller are integrally cast, and the back blade is located on the outside of the impeller rear cover plate, in the middle of the impeller flow channel in the circumferential direction, and is staggered with the impeller blades; the thickness of the rear cover plate outlet position is linearly thinned on the outside to form a slope, and the front cover plate extends slightly toward the outlet direction, and the front cover plate outlet and the rear cover plate outlet are connected on the axial plane to form an inclined surface for water discharge. The number of back blades is consistent with the number of impeller blades, and the back blade outlet diameter is equal to the impeller outer diameter D2. Through the above optimized design, the fire pump has the advantages of simple structure, low modification cost, and convenient maintenance. While reducing the adverse effects of structural deformation on the hydraulic structure, the impeller axial force is balanced, the pressure pulsation is reduced to reduce the vibration and noise of the pump, the reliability of the structure is enhanced, the stable operation of the pump is guaranteed, and the service life of the water pump is increased in disguise, achieving the purpose of improving the market competitiveness of the vertical single-stage fire pump.

[0004] However, the above-mentioned fire pump has design limitations, poor adaptability, humps, high cavitation, strong vibration and poor stability. Therefore, in response to these problems, the applicant proposes a double-suction centrifugal fire pump with low cavitation performance to solve the above-mentioned problems and improve working performance and efficiency. The fire pump significantly improves the corresponding head in the small flow area, and under large flow conditions, the head increase is clearer, so that the head curve has a trend of steepening, effectively eliminating the hump in the small flow area; and the cavitation is low, the flow state outside the impeller outlet is stable, the vibration is low, the stability is good, and the reliability of product operation is improved. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings in the prior art and to propose a double-suction centrifugal fire pump with low cavitation performance.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A double-suction centrifugal fire pump with low cavitation performance comprises a motor and an electric pump, the electric pump comprises a bracket, a coupling, a pump shaft, a pump cover gland, a pump cover, a mechanical seal, a casing, an impeller, a water-guide bearing body, a base, and a volute, the motor is fixed on the bracket, the motor is connected to the pump shaft through a coupling, the pump cover is mounted on the casing around the pump shaft, the pump cover gland is mounted on the pump cover and forms a sealing structure with the mechanical seal, the pump shaft is mounted on the base through the water-guide bearing body, the impeller is mounted on the pump shaft and is located in the volute, the volute is mounted in the casing, the impeller adopts a double-suction impeller structure, and is characterized in that: a guide cone is installed in the middle of the inner side wall of the volute, and the guide cone is formed by the intersection of a first guide cone plane and a second guide cone plane; the first guide cone The angle formed by the plane and the plane of the second guide cone is A, 10°<A<30°; an inlet turbulence device with a fish skeleton structure is arranged on the outer wall of the volute, the inlet turbulence device is located in the flow channel of the inlet section of the outer shell, and the inlet turbulence device includes a plurality of turbulence guide vanes, the turbulence guide vanes are in a circular arc plate structure, and the arc length of the turbulence guide vanes gradually increases along the water flow direction; a plurality of auxiliary jet holes are symmetrically arranged on the wall surface of the volute close to the flow channel side of the inlet section of the outer shell; a blade booster part is arranged at the blade outlet end of the double-suction impeller, the blade booster part is in a pointed structure, and the pointed corner of the blade booster part and the pointed corner of the guide cone are staggered in the axial direction; the flow channel directions of the auxiliary jet holes all point to the middle flow channel formed by the blade booster part and the guide cone.

[0008] Furthermore, the width of the outlet flow channel of the double-suction impeller is L, and the distance between the sharp corner of the blade booster portion and the sharp corner of the guide cone in the radial direction is D1, wherein D1=(1.1-1.6)L.

[0009] Furthermore, the outlet flow channel width of the double-suction impeller is L, and the axial offset distance between the sharp corner of the blade booster portion and the sharp corner of the guide cone is D2, where D2=(0.1-0.3)L.

[0010] Furthermore, the aperture of the auxiliary jet hole is d, wherein d=(10.6-15.8) mm.

[0011] Furthermore, along the water flow direction, the arc lengths of the plurality of turbulence guide vanes vary in a geometric progression, wherein the common ratio q=2-6.

[0012] Furthermore, the included angle of the sharp corner of the blade booster portion is B, wherein 30°<B<60°.

[0013] Furthermore, the volute also includes a volute tongue, and the contour lines of the volute tongue from inside to outside along the water flow direction include an arc line m1, a broken line segment m2, and an arc line m3 in sequence.

[0014] Furthermore, the arc line m1 is an arc line convex toward the inner side of the flow channel, and the arc line m3 is an arc line convex toward the side away from the flow channel.

[0015] Furthermore, the radius of the arc line m1 is R1, and the radius of the arc line m3 is R3, wherein 0.6 R1≤R3<1.5R1.

[0016] Furthermore, the broken line segment m2 is formed by the intersection of two straight line segments, and the included angle of the broken line segment m2 is C, wherein 45°<C≤80°.

[0017] Furthermore, the arc line m1 and the broken line segment m2 intersect at point a, and the broken line segment m2 and the arc line m3 intersect at point b, and a flat slit channel is formed between point a and point b.

[0018] Furthermore, the cross section of the slit channel is an elliptical structure.

[0019] The invention discloses a double-suction centrifugal fire pump with low cavitation performance, wherein a guide cone is installed at the middle of the inner wall of a volute, and the guide cone is formed by the intersection of a first guide cone plane and a second guide cone plane; the angle formed by the first guide cone plane and the second guide cone plane is A, 10°<A<30°; an inlet turbulence device with a fish skeleton structure is arranged on the outer wall of the volute, and the inlet turbulence device is located in the flow channel of the inlet section of the shell, and the inlet turbulence device includes a plurality of turbulence guide vanes, and the turbulence guide vanes are in an arc plate structure, and the arc length of the turbulence guide vanes gradually increases along the water flow direction; a plurality of auxiliary jet holes are symmetrically arranged on the wall surface of the volute near the flow channel side of the inlet section of the shell; a blade booster part is arranged at the blade outlet end of the double-suction impeller, and the blade booster part is in a pointed structure, and the pointed corner part of the blade booster part and the pointed corner part of the guide cone are staggered in the axial direction; the flow channel directions of the auxiliary jet holes all point to the middle flow channel formed by the blade booster part and the guide cone. Due to the improvement of the fire pump structure, the design limitations of the fire pump, poor adaptability, humps, high cavitation, strong vibration and poor stability and other problems have been solved. The effects of eliminating humps, reducing cavitation, good stability, low vibration and high reliability have been achieved, thereby improving the working performance and operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a double-suction centrifugal fire pump;

[0021] Figure 2 A partial enlarged schematic diagram of the double-suction centrifugal fire pump Figure 1 ;

[0022] Figure 3 A partial enlarged schematic diagram of the double-suction centrifugal fire pump Figure 2 ;

[0023] Figure 4 A partial enlarged schematic diagram of the double-suction centrifugal fire pump Figure 3 ;

[0024] Figure 5 Schematic diagram of the detailed structure of the snail tongue.

[0025] In the figure: motor 1, bracket 2, coupling 3, pump shaft 4, pump cover gland 5, pump cover 6, mechanical seal 7, housing 8, impeller 9, water guide bearing body 10, base 11, volute 12, guide cone 13, first guide cone plane 131, second guide cone plane 132, auxiliary jet hole 14, blade booster 15, inlet turbulence device 16, turbulence guide vane 161, volute tongue 17, the angle A formed by the first guide cone plane 131 and the second guide cone plane 132, the outlet flow of the double-suction impeller 9 The channel width L, the radial distance D1 between the sharp corner of the blade booster part 15 and the sharp corner of the guide cone 13, the axial offset distance D2 between the sharp corner of the blade booster part 15 and the sharp corner of the guide cone 13, the aperture d of the auxiliary jet hole 14, the angle B of the sharp corner of the blade booster part 15, the radius R1 of the arc line m1, the radius R3 of the arc line m3, the broken line segment m2, the angle C of the broken line segment m2, the intersection of the arc line m1 and the broken line segment m2 at point a, and the intersection of the broken line segment m2 and the arc line m3 at point b. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0028] like Figure 1-5As shown, a double-suction centrifugal fire pump with low cavitation performance includes a motor 1 and an electric pump. The electric pump includes a bracket 2, a coupling 3, a pump shaft 4, a pump cover gland 5, a pump cover 6, a mechanical seal 7, a shell 8, an impeller 9, a water-guided bearing body 10, a base 11, and a volute 12. The motor 1 is fixed on the bracket 2, the motor 1 is connected to the pump shaft 4 through the coupling 3, the pump cover 6 is installed on the shell 8 around the pump shaft 4, the pump cover gland 5 is installed on the pump cover 6 and forms a sealing structure with the mechanical seal 7, the pump shaft 4 is installed on the base 11 through the water-guided bearing body 10, the impeller 9 is installed on the pump shaft 4 and is located in the volute 12, the volute 12 is installed in the shell 8, and the impeller 9 adopts a double-suction impeller structure, which is characterized in that: a guide cone 13 is installed in the middle of the inner side wall of the volute 12, and the guide cone 13 is formed by the intersection of a first guide cone plane 131 and a second guide cone plane 132 ; The angle formed by the first guide cone plane 131 and the second guide cone plane 132 is A, 10°<A<30°; An inlet turbulence device 16 with a fish skeleton structure is arranged on the outer wall of the volute 12, and the inlet turbulence device 16 is located in the flow channel of the inlet section of the outer shell. The inlet turbulence device 16 includes a plurality of turbulence guide vanes 161, and the turbulence guide vanes 161 are in a circular arc plate structure. Along the direction of the water flow, the arc length of the turbulence guide vanes 161 gradually becomes longer; A plurality of auxiliary jet holes 14 are symmetrically arranged on the wall surface of the volute 12 near the flow channel side of the inlet section of the outer shell; A blade booster 15 is arranged at the blade outlet end of the double-suction impeller 9, and the blade booster 15 is in a pointed structure, and the pointed corner of the blade booster 15 is staggered with the pointed corner of the guide cone 13 in the axial direction; The flow channel direction of the auxiliary jet holes 14 all points to the middle flow channel formed by the blade booster 15 and the guide cone 13.

[0029] The inlet turbulence device 16 of the arc plate structure guides the inlet fluid to make the flow more stable, reduce the risk of cavitation, and reduce vibration. Due to the coordinated use of the guide cone 13 and the blade booster 15, the fluid forms a laminar flow effect, eliminating the impact of the fluid impacting the volute, eliminating the hump, and is beneficial to improving the efficiency of the impeller. The auxiliary jet hole 14 introduces the fluid into the volute from the inlet side, accelerating the flow of the fluid to eliminate the hump, reduce cavitation, have good stability, low vibration, high reliability, etc., and improve the working performance and operating efficiency.

[0030] Furthermore, the outlet flow channel width of the double-suction impeller 9 is L, and the distance between the sharp corner of the blade booster portion 15 and the sharp corner of the guide cone 13 in the radial direction is D1, wherein D1=(1.1-1.6)L.

[0031] Furthermore, the outlet flow channel width of the double-suction impeller 9 is L, and the axial offset distance between the sharp corner of the blade booster portion 15 and the sharp corner of the guide cone 13 is D2, wherein D2=(0.1-0.3)L.

[0032] Furthermore, the aperture of the auxiliary jet hole 14 is d, where d=(10.6-15.8) mm.

[0033] Furthermore, along the water flow direction, the arc lengths of the plurality of turbulence guide vanes 161 vary in a geometric progression, wherein the common ratio q=2-6.

[0034] Furthermore, the included angle of the sharp corner of the blade supercharging portion 15 is B, wherein 30°<B<60°.

[0035] Furthermore, the volute 12 further includes a volute tongue 17 , and the contour lines of the volute tongue 17 from inside to outside along the water flow direction sequentially include an arc line m1 , a broken line segment m2 , and an arc line m3 .

[0036] Furthermore, the arc line m1 is an arc line convex toward the inner side of the flow channel, and the arc line m3 is an arc line convex toward the side away from the flow channel.

[0037] Furthermore, the radius of the arc line m1 is R1, and the radius of the arc line m3 is R3, wherein 0.6 R1≤R3<1.5R1.

[0038] Furthermore, the broken line segment m2 is formed by the intersection of two straight line segments, and the included angle of the broken line segment m2 is C, wherein 45°<C≤80°.

[0039] Furthermore, the arc line m1 and the broken line segment m2 intersect at point a, and the broken line segment m2 and the arc line m3 intersect at point b, and a flat slit channel is formed between point a and point b.

[0040] Furthermore, the cross section of the slit channel is an elliptical structure.

[0041] The above structure of the volute tongue is optimized according to the characteristics of the double-suction impeller, which improves the imbalance of the flow velocity distribution at the outlet, can suppress the stripping effect under the operation condition of large flow at the highest efficiency point, and improves the head and efficiency of the pump.

[0042] The invention discloses a double-suction centrifugal fire pump with low cavitation performance, wherein a guide cone is installed at the middle of the inner wall of a volute, and the guide cone is formed by the intersection of a first guide cone plane and a second guide cone plane; the angle formed by the first guide cone plane and the second guide cone plane is A, 10°<A<30°; an inlet turbulence device with a fish skeleton structure is arranged on the outer wall of the volute, and the inlet turbulence device is located in the flow channel of the inlet section of the shell, and the inlet turbulence device includes a plurality of turbulence guide vanes, and the turbulence guide vanes are in an arc plate structure, and the arc length of the turbulence guide vanes gradually increases along the water flow direction; a plurality of auxiliary jet holes are symmetrically arranged on the wall surface of the volute near the flow channel side of the inlet section of the shell; a blade booster part is arranged at the blade outlet end of the double-suction impeller, and the blade booster part is in a pointed structure, and the pointed corner part of the blade booster part and the pointed corner part of the guide cone are staggered in the axial direction; the flow channel directions of the auxiliary jet holes all point to the middle flow channel formed by the blade booster part and the guide cone. Due to the improvement of the fire pump structure, the design limitations of the fire pump, poor adaptability, humps, high cavitation, strong vibration and poor stability and other problems have been solved. The effects of eliminating humps, reducing cavitation, good stability, low vibration and high reliability have been achieved, thereby improving the working performance and operating efficiency.

Claims

1. A double-suction centrifugal fire pump with low cavitation performance, comprising a motor (1) and an electric pump, the electric pump comprising a bracket (2), a coupling (3), a pump shaft (4), a pump cover gland (5), a pump cover (6), a mechanical seal (7), a housing (8), an impeller (9), a water-conducting bearing body (10), a base (11), and a volute (12), wherein the motor (1) is fixed on the bracket (2), the motor (1) is connected to the pump shaft (4) through the coupling (3), the pump cover (6) is mounted on the housing (8) around the pump shaft (4), the pump cover gland (5) is mounted on the pump cover (6) and forms a sealing structure with the mechanical seal (7), the pump shaft (4) is mounted on the base (11) through the water-conducting bearing body (10), the impeller (9) is mounted on the pump shaft (4) and is located in the volute (12), the volute (12) is mounted in the housing (8), the impeller (9) adopts a double-suction impeller structure, and is characterized in that: A guide cone (13) is installed at the middle of the inner wall of the volute (12), and the guide cone (13) is formed by the intersection of a first guide cone plane (131) and a second guide cone plane (132); the angle formed by the first guide cone plane (131) and the second guide cone plane (132) is A, and 10°<A<30°; an inlet turbulence device (16) with a fish skeleton structure is arranged on the outer wall of the volute (12), and the inlet turbulence device (16) is located in the flow channel of the inlet section of the shell, and the inlet turbulence device (16) includes a plurality of turbulence guide vanes (161), and the turbulence guide vanes ( The turbulence guide vane (161) is in an arc plate structure, and the arc length of the turbulence guide vane (161) gradually increases along the water flow direction; a plurality of auxiliary jet holes (14) are symmetrically arranged on the wall surface of the volute (12) on the flow channel side of the shell inlet section; a blade booster part (15) is arranged at the blade outlet end of the double-suction impeller, and the blade booster part (15) is in a pointed angle structure, and the pointed angle of the blade booster part (15) and the pointed angle of the guide cone (13) are staggered in the axial direction; the flow channel direction of the auxiliary jet holes (14) all points to the middle flow channel formed by the blade booster part (15) and the guide cone (13).

2. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 1, characterized in that: The width of the outlet flow channel of the double-suction impeller is L, and the distance between the sharp corner of the blade booster part (15) and the sharp corner of the guide cone (13) in the radial direction is D1, wherein D1=(1.1-1.6)L.

3. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 1, characterized in that: The width of the outlet flow channel of the double-suction impeller is L, and the axial offset distance between the sharp corner of the blade booster part (15) and the sharp corner of the guide cone (13) is D2, wherein D2=(0.1-0.3)L.

4. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 1, characterized in that: The aperture of the auxiliary jet hole (14) is d, wherein d=(10.6-15.8) mm.

5. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 1, characterized in that: Along the water flow direction, the arc lengths of the plurality of turbulence guide vanes (161) change in a geometric progression, wherein the common ratio q=2-6, and q is an integer.

6. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 1, characterized in that: The included angle of the sharp corner of the blade booster portion (15) is B, wherein 30°<B<60°.

7. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 1, characterized in that: The volute (12) further comprises a volute tongue (17), and the contour lines of the volute tongue (17) from inside to outside along the water flow direction sequentially comprise an arc line m1, a broken line segment m2, and an arc line m3.

8. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 7, characterized in that: The arc line m1 is an arc line convex toward the inner side of the flow channel, and the arc line m3 is an arc line convex toward the side away from the flow channel.

9. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 8, characterized in that: The radius of the arc line m1 is R1, and the radius of the arc line m3 is R3, wherein 0.6 R1≤R3<1.5 R1.

10. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 7, characterized in that: The broken line segment m2 is formed by the intersection of two straight line segments, and the included angle of the broken line segment m2 is C, where 45°<C≤80°.

11. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 7, characterized in that: The arc line m1 and the broken line segment m2 intersect at point a, and the broken line segment m2 and the arc line m3 intersect at point b, forming a flat slit channel between point a and point b.

12. A double-suction centrifugal fire pump with low cavitation performance as claimed in claim 11, characterized in that: The cross section of the slit channel is an elliptical structure.

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