Wide-working-condition-range low-specific-speed gas-liquid multiphase pump and design method thereof

Abstract

The invention discloses a wide-working-condition-range low-specific-speed gas-liquid multiphase pump and a design method thereof. A separation impeller is arranged between an inlet section and a pump body, exhaust holes are formed in a rear cover plate of a centrifugal impeller, back blades are arranged on the back face of the rear cover plate of the centrifugal impeller, an exhaust impeller is arranged behind the centrifugal impeller, and a second exhaust opening is formed in the pump body. A first exhaust port is formed in the pump cover, the first exhaust port is in butt joint with a second exhaust port, the front end of the first exhaust port is located behind the exhaust impeller, the separation impeller, the centrifugal impeller and the exhaust impeller are sequentially arranged in the flow direction, and gas-liquid two-phase media are separated in the separation impeller firstly; and then liquid-phase and gas-phase media are conveyed through the centrifugal impeller and the exhaust impeller respectively, so that the problem that the low-specific-speed gas-liquid multiphase pump cannot stably operate under the working condition of high gas content is effectively solved, the gas-liquid layering state is flexibly adjusted under the conditions of different flows and gas contents, and the device can operate within the wide gas content range.

Description

Technical Field

[0001] The invention relates to a gas-liquid mixed delivery pump, in particular to a gas-liquid mixed delivery pump with a wide operating range and a low specific speed and a design method thereof. Background Art

[0002] In view of the fact that the exploitation of oil and gas resources on land and in shallow waters has reached its limit, the development of deep-sea oil and gas resources is particularly urgent. Among some existing gas-liquid mixed pumps, axial-flow gas-liquid mixed pumps belong to medium-high specific speed pumps, and their applicable transportation conditions are mainly medium-high flow and low head. Therefore, when high head is required, it must be achieved by increasing the number of pump stages. However, increasing the number of pump stages will increase the axial size and the loss between the two stages, which will eventually lead to low operating efficiency. Although the centrifugal gas-liquid mixed pump (low specific speed pump) only needs a smaller number of stages to achieve performance indicators similar to those of the axial flow pump. However, due to the design characteristics of the centrifugal impeller, the centrifugal gas-liquid mixed pump can only transport those media with low gas content. When dealing with high gas content conditions, gas retention is prone to occur, resulting in a decrease in pump performance. In addition, when the actual operating flow rate of the centrifugal gas-liquid mixed pump is lower than the design flow rate, its efficiency will drop sharply. Summary of the invention

[0003] The technical task of the present invention is to address the deficiencies of the above prior art and to provide a low specific speed gas-liquid mixed transmission pump with a wide operating range (wide high efficiency range and wide gas content range) and a design method thereof.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a wide operating range low specific speed gas-liquid mixed transmission pump, including an inlet section, a pump body and a pump cover, a centrifugal impeller and a main shaft located in the pump body, and a booster blade located on the centrifugal impeller, a support body is provided in the inlet section, an annular motor is provided between the inlet section and the pump body, a separation impeller is provided in the annular motor, the two ends of the separation impeller are respectively connected to the support body and the main shaft through bearings, an exhaust hole is provided on the rear cover plate of the centrifugal impeller, a back blade is provided on the back of the rear cover plate of the centrifugal impeller, an exhaust impeller is provided at the rear of the centrifugal impeller, a second exhaust port is provided on the pump body, a first exhaust port is provided on the pump cover, and the first exhaust port is connected to the second The exhaust ports are butt-jointed, and the front end of the first exhaust port is located behind the exhaust impeller; the hub of the separation impeller is a curvature structure, and the inlet edge of the separation blade on the separation impeller is swept back in the rotation direction, and the number of separation blades on the separation impeller is the same as the number of exhaust holes; such a design helps the separation impeller to have not only rotational centrifugal force but also increased curvature centrifugal force compared to a conventional impeller, so that the separation impeller has better gas-liquid separation ability; the inlet edge of the separation blade is swept back in the rotation direction. Such a design makes the gas-liquid two-phase medium on the hub side firstly affected by the blades, and the gas and liquid have begun to separate at the inlet of the separation impeller, further enhancing the gas-liquid separation ability of the separation impeller; on the circumference at the outlet of the separation impeller, the exhaust hole is located between the two separation blades.

[0005] Further improvement: the number of the boost blades is the same as the number of the back blades, the boost blades and the back blades have the same bending direction, and the boost blades and the back blades are alternately arranged.

[0006] Further improvement: the exhaust hole is a waist-shaped hole.

[0007] A design method for a low specific speed gas-liquid mixed transport pump with a wide operating range, the specific steps are as follows:

[0008] Step 1: First determine the basic parameters of the separation impeller, centrifugal impeller, and exhaust impeller. According to the design requirements, when the design head of the gas-liquid mixed pump is H, the flow rate is Q, the speed is n, and the maximum gas content is α, the flow rate of the separation impeller is Q1=(0.6~0.8)Q, and the head of the separation impeller is , the flow rate of the centrifugal impeller is Q2=Q(1-α / 2), the head of the centrifugal impeller is H2=H-0.6H1, the flow rate of the exhaust impeller is Q3=Qα, and the head of the exhaust impeller is H3=3~6m.

[0009] Step 2: Determine the outlet diameter D2 and outlet width b2 of the centrifugal impeller, where: , , where n s1 is the specific speed of the centrifugal impeller, , , at large specific speed, K D2 and K b2 Take a smaller value, at a small specific speed, K D2 and K b2 Take the larger value.

[0010] Step 3: Determine the inlet diameter D1 of the centrifugal impeller and the rim diameter D3 of the separation impeller. The inlet diameter D1 of the centrifugal impeller and the rim diameter D3 of the separation impeller are equal, that is, , , , the hub diameter D of the centrifugal impeller h It is equal to the hub diameter D4 of the separation impeller, that is, , where e=0.15~0.35.

[0011] Step 4: Determine the parameters of the separation impeller, the angle between the inlet edge of the separation blade on the separation impeller and the axis , and the inlet edge of the separation blade is swept back in the direction of rotation, and the sweep angle , the angle between the outlet edge of the separation blade and the axis , the inlet angle of the separation blade , the inlet angle of the separation blade increases gradually from the rim side to the hub side, and the outlet angle of the separation blade The outlet angle of the separation blade increases from the rim side to the hub side, and the inlet angle of the booster blade increases. .

[0012] Step 5: Determine the geometric parameters of the exhaust hole on the centrifugal impeller. According to the geometric models of the separation impeller and the centrifugal impeller, use CFD simulation to obtain the flow field with the maximum gas content α in the separation impeller, construct the axial gas phase distribution data of the separation impeller, and measure the outlet diameter D of the gas phase zone. F ;

[0013] When the exhaust hole is a waist-shaped hole, the inner diameter of the waist-shaped hole , the outer diameter of the waist-shaped hole The outlet diameter D of the gas phase zone in the separation impeller F Equal, where D h is the hub diameter of the centrifugal impeller, when D h When ≤100mm, the number of exhaust holes is one third of the number of supercharger blades. h When the diameter is greater than 100 mm, the number of exhaust holes is half of the number of boost blades.

[0014] Step 6: Determine the inlet edge position and inlet angle of the booster blade on the centrifugal impeller, and the axial distance from the intersection of the inlet edge of the booster blade and the front cover to the intersection of the inner contour of the exhaust hole and the rear cover , the axial distance from the intersection of the inlet edge of the supercharger blade and the rear cover to the intersection of the outer contour of the exhaust hole and the rear cover ;

[0015] Step 7: Determine the geometric parameters of the exhaust impeller. When the design flow rate of the exhaust impeller is Q3 and the head H3=3~6m, the rim diameter of the exhaust impeller is , hub diameter of exhaust impeller , the inlet angle of the exhaust impeller , outlet angle of exhaust impeller , v m1 is the outlet axial velocity, u1 is the circumferential velocity of the exhaust blades;

[0016] Step 8: Diameter of the First Exhaust Port , the diameter of the first exhaust port is the same as that of the second exhaust port.

[0017] Advantages of the present invention: The present invention provides a low specific speed gas-liquid mixed flow pump with a wide operating range, which adopts a separation impeller, a centrifugal impeller and an exhaust impeller arranged in sequence along the flow direction, first completing the separation of the gas-liquid two-phase medium in the separation impeller, and then transporting the liquid phase and gas phase medium through the centrifugal impeller and the exhaust impeller respectively, thereby effectively solving the problem that the low specific speed gas-liquid mixed flow pump cannot operate stably under high gas content conditions. The design controls the speed of the separation impeller separately through the built-in motor, realizes flexible adjustment of the gas-liquid stratification state under different flow rates and gas content conditions, and enables the device to operate in a wide gas content range. In addition, the application of the separation impeller effectively compensates for the problem of excessive shaft power of the centrifugal impeller under small flow conditions, thereby achieving high efficiency and energy saving effects of the gas-liquid mixed flow pump under a wide range of working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention.

[0019] Figure 2 It is a structural schematic diagram of the centrifugal impeller of the present invention.

[0020] Figure 3 It is a schematic diagram of the dimensions of the centrifugal impeller of the present invention.

[0021] Figure 4 It is a schematic diagram of the position of the waist-shaped hole of the present invention.

[0022] Figure 5 It is a schematic diagram of the positions of the booster blades and back blades of the present invention.

[0023] Figure 6 It is a structural schematic diagram of the separation impeller of the present invention.

[0024] Figure 7 It is an axial schematic diagram of the separation impeller of the present invention.

[0025] Figure 8 It is a schematic diagram of gas-liquid separation in the separation impeller of the present invention.

[0026] Fig. 9 It is a schematic structural diagram of the exhaust impeller of the present invention.

[0027] Fig.10 It is a schematic diagram of the position structure of the separation blade and the exhaust hole of the present invention.

[0028] Fig.11 It is a schematic diagram of the inlet angle and outlet angle of the separation blade of the present invention.

[0029] Fig.12 It is a schematic diagram of the inlet angle and outlet angle of the exhaust impeller of the present invention.

[0030] Fig.13 This is a gas phase distribution diagram in the separation impeller of the present invention under CFD simulation state.

[0031] Fig.14 It is a comparison chart of the lift of the present invention and the conventional design at different gas content rates.

[0032] Fig.15 This is a comparison chart of the efficiency of the present invention and the conventional design when the gas content is 5%.

[0033] In the figure: inlet section 1, support body 11, separation impeller 2, bearing 20, separation blades 21, gas phase region 22, liquid phase region 23, ring motor 3, pump body 4, outlet 40, second exhaust port 41, centrifugal impeller 5, exhaust hole 51, booster blade 52, back blade 53, pump cover 6, first exhaust port 61, exhaust impeller 7, main shaft 8, main motor 9. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings.

[0035] As shown in the figure, a wide operating range low specific speed gas-liquid mixed transport pump comprises an inlet section 1, a pump body 4 and a pump cover 6, a centrifugal impeller 5 and a main shaft 8 located in the pump body 4, and a booster blade 52 located on the centrifugal impeller 5, a support body 11 is provided in the inlet section 1, an annular motor 3 is provided between the inlet section 1 and the pump body 4, a separation impeller 2 is provided in the annular motor 3, two ends of the separation impeller 2 are respectively connected to the support body 11 and the main shaft 8 through bearings 20, an exhaust hole 51 is provided on the rear cover plate of the centrifugal impeller 5, a back blade 53 is provided on the back of the rear cover plate of the centrifugal impeller 5, an exhaust impeller 7 is provided behind the centrifugal impeller 5, a second exhaust port 41 is provided on the pump body 4, a first exhaust port 61 is provided on the pump cover 6, the first exhaust port 61 is butt-jointed with the second exhaust port 41, and the front end of the first exhaust port 61 is located behind the exhaust impeller 7.

[0036] The hub of the separation impeller 2 has a curvature structure, and the inlet edge of the separation blade 21 on the separation impeller 2 is swept back in the rotation direction. The number of the separation blades 21 on the separation impeller 2 is the same as the number of the exhaust holes 51, and the exhaust holes 51 are waist-shaped holes; on the circumference at the outlet of the separation impeller 2, the exhaust holes 51 are located between the two separation blades 21.

[0037] The number of the boost blades 52 is the same as the number of the back blades 53 , the boost blades 52 and the back blades 53 have the same bending direction, and the boost blades 52 and the back blades 53 are alternately arranged.

[0038] Its working principle is: the gas-liquid two-phase medium enters from the inlet section 1, the ring motor 3 drives the separation impeller 2 to rotate, and due to the high density difference between gas and liquid in the separation impeller 2, the liquid moves to the rim and the gas moves to the hub, so the gas and liquid are stratified in the separation impeller 2, the area where the gas in the center of the separation impeller 2 is located is the gas phase area 22, and the outer edge is the liquid phase area 23.

[0039] After the stratified gas-liquid two-phase medium enters the centrifugal impeller 5, the main shaft 8 is driven to rotate by the main motor 9, and the main shaft 8 drives the centrifugal impeller 5 and the exhaust impeller 7 to rotate, and the gas and a small amount of liquid enter the inlet of the back blade 53 of the centrifugal impeller 5 from the exhaust hole 51. The centrifugal force generated by the rotation of the back blade 53 and the suction action of the exhaust impeller 7 perform a secondary separation of gas and liquid. The liquid is transported to the outlet 40 of the pump body 4 by the back blade 53, and the gas enters the first exhaust port 61 through the exhaust impeller 7, and then flows through the second exhaust port 41 into the outlet 40, and the gas-liquid mixing is completed at the outlet 40 of the pump body 4, and finally the mixed medium is discharged.

[0040] Embodiment: A design method for a wide operating range low specific speed gas-liquid mixed transport pump, the specific steps are as follows: Step 1: First determine the basic parameters of the separation impeller, centrifugal impeller, and exhaust impeller. According to the design requirements, when the design head of the gas-liquid mixed transport pump is H=100m and the flow rate is Q=300m 3 / h, speed n = 1450rpm, maximum air content α is 0.3, the flow rate of the separation impeller Q1 = 0.6 × 300 = 180m3 / h, the head of the separation impeller , the flow rate of the centrifugal impeller is Q2=Q(1-α / 2)=255m3 / h, the head of the centrifugal impeller is H2=H-0.6H1=100-0.6×10.51=93.69m, the flow rate of the exhaust impeller is Q3=Qα=90m3 / h, and the head of the exhaust impeller is H3=5m;

[0041] Step 2: Determine the outlet diameter D2 and outlet width b2 of the centrifugal impeller, where: , , where K D2 =1.15, K b2 =1.75, n s1 =47.

[0042] Step 3: Determine the inlet diameter D1 of the centrifugal impeller and the rim diameter D3 of the separation impeller. The inlet diameter D1 of the centrifugal impeller and the rim diameter D3 of the separation impeller are equal, that is, , , , the hub diameter D of the centrifugal impeller h It is equal to the hub diameter D4 of the separation impeller, that is, , where e=0.225;

[0043] Step 4: Determine the parameters of the separation impeller, the angle between the inlet edge of the separation blade on the separation impeller and the axis , and the inlet edge of the separation blade is swept back in the direction of rotation, and the sweep angle , the angle between the outlet edge of the separation blade and the axis , the inlet angle of the separation blade The inlet angle of the separation blade increases gradually from the rim side to the hub side, and the outlet angle of the separation blade increases gradually from the rim side to the hub side. The outlet angle of the separation blade increases from the rim side to the hub side, and the inlet angle of the booster blade increases. .

[0044] Step 5: Determine the geometric parameters of the exhaust hole on the centrifugal impeller. According to the geometric models of the separation impeller and the centrifugal impeller, use CFD simulation to obtain the flow field with a maximum gas content of 30% in the separation impeller, construct the axial gas phase distribution data of the separation impeller, and measure the outlet diameter D of the gas phase zone. F =100mm, e.g. Fig.13 In the figure, the blue area is the liquid phase area 23, and the red area is the gas phase area 22.

[0045] When the exhaust hole is a waist-shaped hole, the inner diameter of the waist-shaped hole , the outer diameter of the waist-shaped hole The outlet diameter D of the gas phase zone in the separation impeller F Equal, where D h is the hub diameter of the centrifugal impeller, and the number of exhaust holes is 3.

[0046] Step 6: Determine the inlet edge position and inlet angle of the booster blade on the centrifugal impeller, and the axial distance from the intersection of the inlet edge of the booster blade and the front cover to the intersection of the inner contour of the exhaust hole and the rear cover , the axial distance from the intersection of the inlet edge of the supercharger blade and the rear cover to the intersection of the outer contour of the exhaust hole and the rear cover ;

[0047] Step 7: Determine the geometric parameters of the exhaust impeller. When the design flow rate of the exhaust impeller is Q3=Qα=90m 3 / h, when the head H3=5m, the rim diameter of the exhaust impeller , the hub diameter of the exhaust impeller , the inlet angle of the exhaust impeller , outlet angle of the exhaust impeller , v m1 is 0.86m / s, u1 is 8.05m / s;

[0048] Step 8: Diameter of the First Exhaust Port , the diameter of the first exhaust port is the same as that of the second exhaust port.

[0049] The device was three-dimensionally modeled according to the structural parameters obtained above, and then the tetrahedral mesh was divided using ICEM, followed by CFD numerical simulation to compare the performance of the present invention and the conventional design.

[0050] Fig.14 The figure is a comparison of the lift of the present invention and the conventional design at different gas content rates. Obviously, the present invention still has good supercharging performance when the inlet gas content rate is 30%, but the conventional design has lost its supercharging performance when the inlet gas content rate is 10%, which highlights that the present invention can always maintain a better supercharging capacity in a wide gas content rate range.

[0051] Fig.15 This is a comparison of the efficiency of the present invention and the conventional design when the gas content is 5%. It can be seen from the figure that the efficiency of the present invention is improved over the conventional design in the entire operating range and has a wider high-efficiency area; under small flow conditions, the efficiency is improved by 7% compared with the conventional design.

[0052] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A low specific speed gas-liquid mixed delivery pump with a wide operating range, comprising an inlet section, a pump body and a pump cover, a centrifugal impeller and a main shaft located in the pump body, and booster blades located on the centrifugal impeller, characterized in that: A support body is provided in the inlet section, an annular motor is provided between the inlet section and the pump body, a separation impeller is provided in the annular motor, two ends of the separation impeller are respectively connected to the support body and the main shaft through bearings, an exhaust hole is provided on the rear cover plate of the centrifugal impeller, a back blade is provided on the back of the rear cover plate of the centrifugal impeller, an exhaust impeller is provided behind the centrifugal impeller, a second exhaust port is provided on the pump body, a first exhaust port is provided on the pump cover, the first exhaust port is connected to the second exhaust port, and the front end of the first exhaust port is located behind the exhaust impeller; the hub of the separation impeller is a curvature structure, the inlet edge of the separation blade on the separation impeller is swept back in the rotation direction, the number of separation blades on the separation impeller is the same as the number of exhaust holes, and the exhaust hole is located between two separation blades on the circumference at the outlet of the separation impeller.

2. A wide operating range low specific speed gas-liquid mixed transport pump according to claim 1, characterized in that: The number of the boost blades is the same as the number of the back blades, the boost blades and the back blades have the same bending direction, and the boost blades and the back blades are alternately arranged.

3. The wide operating range and low specific speed gas-liquid mixed transport pump according to claim 1, characterized in that: The exhaust hole is a waist-shaped hole.

4. A design method for a gas-liquid mixed transport pump with a wide operating range and low specific speed, characterized in that: The specific steps are as follows: Step 1: First determine the basic parameters of the separation impeller, centrifugal impeller, and exhaust impeller. According to the design requirements, when the design head of the gas-liquid mixed pump is H, the flow rate is Q, the speed is n, and the maximum gas content is α, the flow rate of the separation impeller is Q1=(0.6~0.8)Q, and the head of the separation impeller is , the flow rate of the centrifugal impeller is Q2=Q(1-α / 2), the head of the centrifugal impeller is H2=H-0.6H1, the flow rate of the exhaust impeller is Q3=Qα, and the head of the exhaust impeller is H3=3~6m; Step 2: Determine the outlet diameter D2 and outlet width b2 of the centrifugal impeller, where: , , where n s1 is the specific speed of the centrifugal impeller, , , at large specific speed, K D2 and K b2 Take a smaller value, at a small specific speed, K D2 and K b2 Take the larger value; Step 3: Determine the inlet diameter D1 of the centrifugal impeller and the rim diameter D3 of the separation impeller. The inlet diameter D1 of the centrifugal impeller and the rim diameter D3 of the separation impeller are equal, that is, , , , the hub diameter D of the centrifugal impeller h It is equal to the hub diameter D4 of the separation impeller, that is, , where e=0.15~0.35; Step 4: Determine the parameters of the separation impeller, the angle between the inlet edge of the separation blade on the separation impeller and the axis , and the inlet edge of the separation blade is swept back in the direction of rotation, and the sweep angle , the angle between the outlet edge of the separation blade and the axis , the inlet angle of the separation blade , the inlet angle of the separation blade increases gradually from the rim side to the hub side, and the outlet angle of the separation blade The outlet angle of the separation blade increases from the rim side to the hub side, and the inlet angle of the booster blade increases. ; Step 5: Determine the geometric parameters of the exhaust hole on the centrifugal impeller. According to the geometric models of the separation impeller and the centrifugal impeller, use CFD simulation to obtain the flow field with the maximum gas content α in the separation impeller, construct the axial gas phase distribution data of the separation impeller, and measure the outlet diameter D of the gas phase zone. F ; When the exhaust hole is a waist-shaped hole, the inner diameter of the waist-shaped hole , the outer diameter of the waist-shaped hole The outlet diameter D of the gas phase zone in the separation impeller F Equal, where D h is the hub diameter of the centrifugal impeller, when D h When ≤100mm, the number of exhaust holes is one third of the number of supercharger blades. h When the diameter is greater than 100 mm, the number of exhaust holes is half of the number of booster blades; Step 6: Determine the inlet edge position and inlet angle of the booster blade on the centrifugal impeller, and the axial distance from the intersection of the inlet edge of the booster blade and the front cover to the intersection of the inner contour of the exhaust hole and the rear cover , the axial distance from the intersection of the inlet edge of the supercharger blade and the rear cover to the intersection of the outer contour of the exhaust hole and the rear cover ; Step 7: Determine the geometric parameters of the exhaust impeller. When the design flow rate of the exhaust impeller is Q3 and the head H3=3~6m, the rim diameter of the exhaust impeller is , hub diameter of exhaust impeller , the inlet angle of the exhaust impeller , outlet angle of exhaust impeller , v m1 is the outlet axial velocity, u1 is the circumferential velocity of the exhaust blades; Step 8: Diameter of the First Exhaust Port , the diameter of the first exhaust port is the same as that of the second exhaust port.

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