A diffuser structure applicable to a cryogenic pump for liquefied natural gas

Abstract

The present invention discloses a diffuser structure applicable to a cryogenic liquid natural gas pump, which includes a first-stage impeller, a second-stage impeller, a first-stage diffuser body, a second-stage diffuser body, a second pump body, a first pump body, a second housing, a first housing, and a pump shaft. The centrifugal impeller includes a front disc and a rear disc. The diffuser body includes a diffuser disc body and an inter-stage three-dimensional twisted diffuser vane (31). The diffuser vane includes a first vane portion (32), a second vane portion (33), and a third vane portion (34) connected in sequence. The first vane portion, the second vane portion, and the third vane portion are integrally formed or integrally constitute the inter-stage three-dimensional twisted diffuser vane. It is characterized in that: the upstream end of the first vane portion has a leading edge portion (35), the blade thickness of the leading edge portion gradually increases along the fluid flow direction, and a flow guiding portion (36) is provided at the end of the leading edge portion. The flow guiding portion is wavy, and the depths of the grooves in the wave trough portions of the wavy shape are not equal. The present invention can effectively reduce pressure pulsation and pre-rotation, thereby improving the operating efficiency of the pump.

Description

Technical Field

[0001] The invention relates to the technical field of liquefied natural gas submersible pumps, and in particular to a guide vane structure suitable for liquefied natural gas submersible pumps. Background Art

[0002] The guide vane is one of the key flow components of the liquefied natural gas submersible pump and is also the main energy-consuming element of the submersible pump. The main function of the guide vane is to collect the liquid thrown out of the impeller, and convert the kinetic energy of the liquid into pressure energy and then transport it to the next impeller inlet or pump outlet. Its performance has an important impact on the performance of the submersible pump.

[0003] Existing submersible pumps suitable for liquefied natural gas, such as Figure 1-2 As shown, it includes a first-stage impeller 1, a second-stage impeller 2, a first-stage guide vane body 3, a second-stage guide vane body 4, a second pump body 5, a first pump body 6, a second shell 7, a first shell 8, and a pump shaft 9. The first-stage impeller 1, the first-stage guide vane body 3, the second-stage impeller 2, and the second-stage guide vane body 4 are arranged in sequence along the axial direction. The first-stage impeller 1 and the second-stage impeller 2 are installed on the pump shaft 9. The first pump body 6 and the second pump body 5 are connected through a positioning stop. The first shell 8 and the second shell 7 are connected through a threaded connector. An inlet pipe 10 is installed at the front end / upstream end of the first shell 8. An inducer 11 and an inlet guide vane body 12 are installed in the inlet pipe 10. The inducer 11 is arranged upstream of the inlet guide vane body 12. The inlet guide vane body 1 2 and the pump shaft 9 are provided with a bearing 13, all impellers are centrifugal impellers, the centrifugal impellers include a front disc 21 and a rear disc 22, the first-stage guide vane body 3 or the second-stage guide vane body 4 includes a guide vane disc body, an interstage three-dimensional twisted guide vane blade 31, the interstage three-dimensional twisted guide vane blade 31 is distributed circumferentially along the guide vane disc body 30, the interstage three-dimensional twisted guide vane blade 31 includes a first blade portion 32, a second blade portion 33, and a third blade portion 34 connected in sequence, the first blade portion 32, the second blade portion 33, and the third blade portion 34 are integrally formed or integrally constitute the interstage three-dimensional twisted guide vane blade 31, the first blade portion 32 extends radially, the second blade portion 33 extends substantially circumferentially, and the third blade portion 34 extends radially. However, the existing guide vane body has the problems of large pressure pulsation and large vortex. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a guide vane structure suitable for a liquefied natural gas submersible pump, which plays a rectifying role through the optimized design of the guide part, controls the vortex entering the next-stage impeller, reduces the pre-swirl at the impeller inlet, and thus improves the operating efficiency of the pump. At the same time, through the design of the voltage stabilizing part, it can more effectively reduce the pressure pulsation, thereby reducing the hidden dangers of induced noise and high-frequency vibration, which helps to extend the service life of the entire submersible pump and improve the working environment of the pump body. While reducing the pressure pulsation and pre-swirl, it can also ensure the force strength / overall strength of the three-dimensional twisted guide vane blades.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A guide vane structure suitable for a liquefied natural gas submersible pump, comprising a primary impeller (1), a secondary impeller (2), a primary guide vane body (3), a secondary guide vane body (4), a second pump body (5), a first pump body (6), a second casing (7), a first casing (8), and a pump shaft (9); the primary impeller, the primary guide vane body, the secondary impeller, and the secondary guide vane body are arranged in sequence along the axial direction; the primary impeller and the secondary impeller are mounted on the pump shaft; the first pump body and the second pump body are connected via a positioning stop; the first casing and the second casing are connected via a threaded connector; all impellers are centrifugal impellers; the centrifugal impellers include a front disc (21) and a rear disc (22); the primary guide vane body and / or the secondary guide vane body include a guide vane disc body (30), an interstage three-dimensional twisted guide vane disc body (31), and a guide vane disc body (32). The blade (31) is a three-dimensional twisted guide vane between stages and is distributed along the circumference of the guide vane disk body. The three-dimensional twisted guide vane between stages includes a first blade portion (32), a second blade portion (33), and a third blade portion (34) which are connected in sequence. The first blade portion, the second blade portion, and the third blade portion 3 are integrally formed or integrally constitute the three-dimensional twisted guide vane between stages. The first blade portion extends radially, the second blade portion generally extends circumferentially, and the third blade portion extends radially. The invention is characterized in that: the upstream end of the first blade portion (32) has a leading edge portion (35), the blade thickness of the leading edge portion gradually increases along the fluid flow direction, and a guide portion (36) is arranged at the end of the leading edge portion. The guide portion is wavy, and the depth of the groove of the wavy trough portion is different.

[0007] Furthermore, in the axial direction, the depth of the groove of the trough portion gradually increases from the front disc (21) to the rear disc (22) side, and the maximum depth of the groove of the trough portion is 2-5 times the minimum depth.

[0008] Furthermore, the leading edge portion (35) has a radial width B1 and an axial length L, wherein L=n*B1, wherein n is a transition coefficient, and the value range of n is 2-5; wherein,

[0009]

[0010] Where: n is the rated speed of the submersible pump, in r / min; Q is the rated flow rate of the submersible pump, in m 3 / s; H—rated head of the submersible pump, unit: m. When designing / calculating, take the numerical part of each parameter for design / calculation.

[0011] Furthermore, the wavy curve is drawn using the second-order system unit step response envelope, which satisfies the functional relationship: Where: ζ is the damping ratio; Among them, taking the entry error ±5%, we can get: When the damping ratio ζ is large, When the damping ratio is small, By the above method, the wave shape of the guide portion (36) at the leading edge is determined.

[0012] Furthermore, a pressure stabilizing portion (37) is provided on one side and / or both side surfaces of the first blade portion (32), the pressure stabilizing portion is adjacent to the downstream of the flow guide portion (36), and the pressure stabilizing portion includes a plurality of recessed portions, and the plurality of recessed portions are distributed in a plurality of array groups.

[0013] Furthermore, in the axial direction, the diameter of the recessed portion gradually increases from the front disc (21) to the rear disc (22) side, and the maximum diameter of the recessed portion is 1.5-3 times the minimum diameter.

[0014] Furthermore, the voltage stabilizing portion (37) has a radial width B2, where B2=(2-4)B1.

[0015] Furthermore, an inlet pipe (10) is installed at the front end / upstream end of the first housing (8), an inducer (11) and an inlet guide vane body (12) are installed in the inlet pipe, the inducer is arranged upstream of the inlet guide vane body, and a bearing (13) is installed between the inlet guide vane body and the pump shaft.

[0016] The guide vane structure of the present invention is suitable for a liquefied natural gas submersible pump. It plays a rectifying role through the optimized design of the guide part, controls the vortex entering the next-stage impeller, reduces the pre-swirl at the impeller inlet, and thus improves the operation efficiency of the pump. At the same time, through the design of the voltage stabilizing part, it can more effectively reduce the pressure pulsation, thereby reducing the hidden dangers of induced noise and high-frequency vibration, which helps to extend the service life of the entire submersible pump and improve the working environment of the pump body. While reducing the pressure pulsation and pre-swirl, it can also ensure the force strength / overall strength of the three-dimensional twisted guide vane blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural diagram of the submersible pump of the present invention / prior art;

[0018] Figure 2 It is a partial structural diagram of the guide vane of the submersible pump of the present invention / the prior art;

[0019] Figure 3 It is a schematic diagram of the front structure of the guide vane of the submersible pump of the present invention;

[0020] Figure 4 It is a schematic diagram of the reverse structure of the guide vane of the submersible pump of the present invention;

[0021] Figure 5 This is a schematic diagram of the structure of a three-dimensional twisted guide vane blade of the present invention;

[0022] Figure 6 It is a schematic diagram of coordinate curve analysis of the guide portion of the guide vane of the present invention;

[0023] Figure 7 It is a schematic diagram of frequency domain analysis of the guide vane pressure pulsation of the present invention;

[0024] Figure 8 It is a schematic diagram of the efficiency curve analysis of the submersible pump with the guide vane form of the present invention.

[0025] In the figure: a first-stage impeller / centrifugal impeller 1, a second-stage impeller 2, a first-stage guide vane body 3, a second-stage guide vane body 4, a second pump body 5, a first pump body 6, a second outer shell 7, a first outer shell 8, a pump shaft 9, an inlet pipe 10, an inducer 11, an inlet guide vane body 12, a bearing 13, a front disc 21, a rear disc 22, a guide vane disc body 30, an inter-stage three-dimensional twisted guide vane blade 31, a first blade portion 32, a second blade portion 33, a third blade portion 34, a leading edge portion 35, a flow guide portion 36, and a pressure stabilizing portion 37. 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 guide vane structure suitable for a liquefied natural gas submersible pump comprises a primary impeller 1, a secondary impeller 2, a primary guide vane body 3, a secondary guide vane body 4, a second pump body 5, a first pump body 6, a second shell 7, a first shell 8, and a pump shaft 9. The primary impeller 1, the primary guide vane body 3, the secondary impeller 2, and the secondary guide vane body 4 are sequentially arranged along the axial direction. The primary impeller 1 and the secondary impeller 2 are mounted on the pump shaft 9. The first pump body 6 and the second pump body 5 are connected by a positioning stopper. The first shell 8 and the second shell 7 are connected by a threaded connector. An inlet pipe 10 is installed at the front end / upstream end of the first shell 8. An inducer 11 and an inlet guide vane body 12 are installed in the inlet pipe 10. The inducer 11 is arranged upstream of the inlet guide vane body 12. A bearing 13 is installed between the inlet guide vane body 12 and the pump shaft 9. All impellers are centrifugal impellers. The centrifugal impellers include a front disc 21 and a rear disc 22. 22. The primary guide vane body 3 and / or the secondary guide vane body 4 include a guide vane disc body 30 and an interstage three-dimensional twisted guide vane blade 31. The interstage three-dimensional twisted guide vane blade 31 is distributed circumferentially along the guide vane disc body 30. The interstage three-dimensional twisted guide vane blade 31 includes a first blade portion 32, a second blade portion 33, and a third blade portion 34 which are connected in sequence. The first blade portion 32, the second blade portion 33, and the third blade portion 34 are integrally formed or integrally constitute the interstage three-dimensional twisted guide vane blade 31. The first blade portion 32 extends radially, the second blade portion 33 extends substantially circumferentially, and the third blade portion 34 extends radially. It is characterized in that: the upstream end of the first blade portion 32 has a leading edge portion 35, and the blade thickness of the leading edge portion 35 gradually increases along the fluid flow direction. A guide portion 36 is provided at the end of the leading edge portion 35. The guide portion 36 is wavy, and the depths of the grooves of the wavy trough portions are not uniform.

[0029] like Figure 5 As shown, further, in the axial direction, from the front disc 21 to the rear disc 22 side, the depth of the groove of the trough portion gradually increases, and the maximum depth of the groove of the trough portion is 2-5 times the minimum depth.

[0030] Furthermore, the leading edge portion 35 has a radial width B1 and an axial length L, wherein L=n*B1, wherein n is a transition coefficient, and the value range of n is 2-5; wherein,

[0031]

[0032] Where: n is the rated speed of the submersible pump, in r / min; Q is the rated flow rate of the submersible pump, in m 3 / s; H—rated head of the submersible pump, unit: m. When designing / calculating, take the numerical part of each parameter for design / calculation.

[0033] Furthermore, the wavy curve is drawn using the second-order system unit step response envelope, which satisfies the functional relationship: Where: ζ is the damping ratio; Among them, taking the entry error ±5%, we can get: When the damping ratio ζ is large, When the damping ratio is small, In the above manner, the wave shape of the guide portion 36 of the leading edge portion 35 is determined. The guide portion 36 is designed to have a curve profile / curve line shape with the same wavelength but periodically changing amplitude.

[0034] Furthermore, a pressure stabilizing portion 37 is provided on one side and / or both side surfaces of the first blade portion 32. The pressure stabilizing portion 37 is adjacent to the downstream of the guide portion 36. The pressure stabilizing portion 37 includes a plurality of recessed portions / grooves, and the plurality of recessed portions are distributed in a plurality of arrays, such as a 3x3 array.

[0035] Furthermore, in the axial direction, the diameter of the recessed portion gradually increases from the front disc 21 to the rear disc 22 side, and the maximum diameter of the recessed portion is 1.5-3 times the minimum diameter.

[0036] Furthermore, the voltage stabilizing portion 37 has a radial width B2, where B2=(2-4)B1, preferably, B2=(2.5-3)B1.

[0037] like Figure 7-8 As shown, from Figure 7 It can be seen that the pressure pulsation amplitude of the three-dimensional twisted guide vane of the present invention is lower than that of the original / existing guide vane. The pressure amplitude peaks of the first and second stages of the original guide vane are 3722310Pa and 7339359Pa respectively, while the pressure pulsation amplitude of the three-dimensional twisted guide vane of the present invention is 3161708Pa and 622875Pa. The pressure pulsation amplitude of the three-dimensional twisted guide vane of the present invention is reduced by about 13% compared with the original guide vane. Figure 8 It can be seen from the figure that we compared the efficiency of the submersible pump using the conventional twisted guide vane and the guide vane with the leading edge curve treatment. It can be clearly seen that after applying the guide vane structure of the present invention, the pump efficiency is significantly improved.

[0038] The guide vane structure of the present invention is suitable for a liquefied natural gas submersible pump. The guide vane structure plays a rectifying role through the optimized design of the guide part 36, controls the vortex entering the next-stage impeller, reduces the pre-swirl at the impeller inlet, and thus improves the operation efficiency of the pump. At the same time, through the design of the voltage stabilizing part 37, the pressure pulsation can be more effectively reduced, thereby reducing the hidden dangers of induced noise and high-frequency vibration, which helps to extend the service life of the entire submersible pump and improve the working environment of the pump body. While reducing the pressure pulsation and pre-swirl, the overall force strength of the three-dimensional twisted guide vane blades can also be guaranteed.

[0039] The above-mentioned implementation modes are for explanation of the present invention rather than limitation of the present invention. It can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A diffuser structure applicable to a cryogenic pump for liquefied natural gas, which includes a first-stage impeller (1), a second-stage impeller (2), a first-stage diffuser body (3), a second-stage diffuser body (4), a second pump body (5), a first pump body (6), a second housing (7), a first housing (8), and a pump shaft (9). The first-stage impeller, the first-stage diffuser body, the second-stage impeller, and the second-stage diffuser body are arranged axially in sequence. The first pump body and the second pump body are connected by a positioning spigot, and the first housing and the second housing are connected by threaded connectors. All impellers are centrifugal impellers, and the centrifugal impeller includes a front disc (21) and a rear disc (22). The first-stage diffuser body and / or the second-stage diffuser body includes a diffuser disc body (30) and inter-stage three-dimensional twisted diffuser vanes (31). The inter-stage three-dimensional twisted diffuser vanes are distributed circumferentially on the diffuser disc body. The inter-stage three-dimensional twisted diffuser vanes include a first vane portion (32), a second vane portion (33), and a third vane portion (34) connected in sequence. The first vane portion, the second vane portion, and the third vane portion are integrally formed to constitute the inter-stage three-dimensional twisted diffuser vanes. The first vane portion extends radially, the second vane portion extends substantially axially, and the third vane portion extends radially; It is characterized in that: The inter-stage three-dimensional twisted diffuser vanes are stationary parts, non-rotating parts; On both sides of the first vane portion (32), there are pressure stabilizing portions (37). The pressure stabilizing portions are adjacent to the downstream of the flow guiding portion (36). The pressure stabilizing portions include a plurality of recessed portions, and the plurality of recessed portions are distributed in multiple groups in an array. Axially, from the front disc (21) to the rear disc (22) side, the diameter of the recessed portions gradually increases, and the maximum diameter of the recessed portions is 1.5 - 3 times the minimum diameter; the pressure stabilizing portion has a radial width B2, B2 = (2 - 4)B1. The upstream end of the first vane portion has a leading edge portion (35), and the leading edge portion has a radial width B1.

2. A diffuser structure applicable to a cryogenic pump for liquefied natural gas according to claim 1, It is characterized in that, The upstream end of the first vane portion (32) has a leading edge portion (35). The blade thickness of the leading edge portion gradually increases along the fluid flow direction. The end of the leading edge portion is provided with a flow guiding portion (36). The flow guiding portion is wavy, and the depths of the grooves at the wave trough portions of the wavy shape are not equal. Axially, from the front disc (21) to the rear disc (22) side, the depth of the groove at the wave trough portion gradually becomes larger, and the maximum depth of the groove at the wave trough portion is 2 - 5 times the minimum depth.

3. A diffuser structure applicable to a cryogenic pump for liquefied natural gas according to claim 2, It is characterized in that, An inlet pipe (10) is installed at the upstream end of the first housing (8). An inducer (11) and an inlet diffuser body (12) are installed in the inlet pipe. The inducer is arranged upstream of the inlet diffuser body, and a bearing (13) is installed between the inlet diffuser body and the pump shaft.

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