CN108825549A - A kind of centrifugal pump radial seal ring with airfoil type guide vane - Google Patents

Abstract

The invention discloses a centrifugal pump radial seal ring with airfoil-shaped guide vanes assembled between the volute and the impeller of the centrifugal pump. A plurality of radial guide vanes are uniformly and fixedly arranged along the circumferential direction, and the radial section profile of the radial guide vanes is an airfoil shape; the disk is fixedly connected to the volute, and the radial guide vanes face the impeller and are aligned with the front of the impeller. The end face of the cover plate maintains an axial gap of Δ=0.5-1mm; the present invention is a non-contact sealing device, which adopts the radial flow direction, and when the impeller of the centrifugal pump rotates, it drives the liquid between the impeller and the volute to rotate The rotating liquid generates directional flow under the induction of fixed radial guide vanes, and the induced direction is opposite to the movement direction of the leakage fluid between the impeller and the volute, so as to prevent the fluid from leaking from the gap between the impeller and the volute.

Description

A centrifugal pump radial seal ring with airfoil guide vanes

technical field

The invention relates to a centrifugal pump structure in the field of fluid machinery, in particular to a radial sealing device of the centrifugal pump, which is installed in the gap between the volute and the impeller to prevent fluid leakage between the volute and the impeller.

Background technique

As a typical vane-type fluid machine, the centrifugal pump works on the principle that the prime mover drives the impeller to rotate to do work on the fluid, converting the mechanical energy into the kinetic energy and pressure energy of the fluid, so as to realize the transportation of the fluid. The work process of the impeller of the centrifugal pump is inevitably accompanied by energy loss. The energy loss is mainly divided into three types: flow loss, volume loss and disc friction loss. Among them, the volume loss refers to the flow loss caused by the leakage between the impeller rotation and the casing. The leakage is related to the pressure difference acting on both ends of the gap and the structure of the gap. Therefore, a sealing device should be installed at the position where the leakage occurs. At present, there are two commonly used sealing methods between the volute and the impeller: one is to set the leakage gap between the mouth ring and the impeller in a small range; the other is to use a labyrinth seal by setting a complex sealing structure. However, when the gap is set to be small, the wear is serious, and the stability will be deteriorated, and an overly complicated sealing structure is not conducive to processing and assembly.

At present, in order to solve a series of problems such as severe wear and difficult assembly caused by reducing the gap, a non-contact sealing structure that can ensure good sealing performance under a large gap has been proposed. For example, Chinese patent application number 201420065364.3 proposes a high-efficiency centrifugal pump with impeller with non-contact sealing function. The annular impeller seal ring extending on both sides of the impeller and the pump body built into the pump body match the impeller seal ring. Threads are processed on the inner surface of the wear-resistant ring to reduce or prevent the leakage at the radial gap of the impeller seal ring, but the processing technology of the impeller itself is relatively complicated. Processing threads on the outer surface of the seal ring will not only increase the processing difficulty, but also Affect the hydraulic performance of the impeller; the thread seal will wear during use, and once the wear is excessive, the entire impeller needs to be replaced, which will increase maintenance costs.

Contents of the invention

The purpose of the present invention is to provide a radial sealing ring of a centrifugal pump, which uses airfoil-shaped radial guide vanes to generate a flow opposite to the leakage direction to prevent fluid from flowing out from the gap between the volute and the impeller, thereby reducing volume loss , to improve the volumetric efficiency of the centrifugal pump.

In order to achieve the above object, the technical solution adopted by the present invention is: the present invention is assembled between the volute and the impeller of the centrifugal pump, and is composed of a disc and radial guide vanes, and is evenly fixed along the circumferential direction on one side of the disc. A plurality of radial guide vanes are arranged, and the profile of the radial section of the radial guide vanes is an airfoil shape.

Further, the disc is fixedly connected to the volute, and the radial guide vane faces the impeller and maintains an axial gap of Δ=0.5-1 mm with the end surface of the front cover plate of the impeller.

Further, the radius r of the inner ring of the disk is 1/2 of the diameter at the inlet of the impeller, the radius R of the outer ring is 1.5-2 times the radius r, and the axial height b is 0.25-0.35 times the radius r.

Further, the number of radial guide vanes is one more than the number of blades of the impeller 5 .

Further, the airfoil type of the radial guide vane is RAF-6E airfoil type and NACA airfoil type.

Further, the vane length L of the radial guide vanes is 1.9-2.2 times the radius r, the axial height h is 0.15-0.2 times the radius r, and the outlet placement angle β is 60°-75°.

The beneficial effects of the present invention are:

1. The present invention is a sealing ring based on a radial guide mechanism. When the centrifugal pump impeller rotates, the liquid between the impeller and the volute is driven to rotate, and the rotating liquid generates directional flow under the induction of fixed radial guide vanes , the induced direction is opposite to the movement direction of the leaked fluid between the impeller and the volute, so as to prevent the fluid from leaking from the gap between the impeller and the volute. Compared with traditional seals that adopt complex structures and reduce leakage gaps, the present invention uses a seal ring with airfoil-shaped radial guide vanes to induce the leakage fluid to move in reverse, and converts the radial gaps in traditional seals into shaft seals. The axial gap can ensure the good sealing performance of the centrifugal pump when the large axial gap means that the end face of the front cover plate of the impeller does not contact the disc, and it also has the advantages of convenient implementation and simple replacement.

2. The present invention is a non-contact sealing device, which adopts the radial guide direction, which is equivalent to setting the sealing surface in the radial direction. This sealing method not only increases the sealing surface, but also makes the sealing performance is improved. Under the same circumstances, the present invention can ensure a good sealing performance when the axial gap between the seal ring and the impeller is Δ=0.5-1mm, which not only reduces the difficulty of processing and assembly, but also greatly reduces the wear of the seal ring during use and prolongs the working life of the seal ring. its service life. Under the same circumstances, the allowable value of the maximum clearance of the present invention is greater than that of the traditional sealing ring. When the nominal diameter of the traditional sealing ring is 120-150mm, the allowable value of the gap between the mouth ring and the impeller radial direction is 0.07-0.44mm, and the wear After the maximum allowable value is 0.6mm.

Description of drawings

Fig. 1 is a three-dimensional structural schematic diagram of a radial seal ring of a centrifugal pump with airfoil guide vanes according to the present invention;

Fig. 2 is a front enlarged view of the structure of the present invention shown in Fig. 1;

Fig. 3 is the bottom view of Fig. 2;

Fig. 4 is a half-sectional view of the assembly structure with the impeller and the volute when the present invention shown in Fig. 1 is installed on the centrifugal pump;

Fig. 5 is an enlarged view of part A in Fig. 4;

In the figure: 1. disc; 2. radial guide vane; 3. countersunk screw hole; 4. volute; 5. impeller.

Detailed ways

Referring to Fig. 1-2, the present invention is made up of disc 1 and radial guide vane 2, and the middle shape of disc 1 has a central through hole. A plurality of radial guide vanes 2 are evenly and fixedly arranged along the circumferential direction on one side of the disc 1, and the radial guide vanes 2 protrude axially from the disc surface of the disc 1, and the radial section of the radial guide vanes 2 The profile shape is that of an airfoil. Several countersunk screw holes 3 are processed on the surface of the disc 1 for fixing the disc 1 . The inner end surfaces of the radial guide vanes 2 are flush with the inner ring of the disc 1 .

Referring to Fig. 4 and Fig. 5, the present invention is installed between the volute 4 and the impeller 5 of the centrifugal pump. During installation, the central axis of the disc 1 is required to be in line with the central axis of the impeller 5, and the countersunk screw is inserted into the countersunk screw hole. The disc 1 is fixedly connected to the volute 4 at 3 places, the radial guide vane 2 faces the impeller 5, and the radial guide vane 2 and the end face of the front cover plate of the impeller 5 maintain an axial installation gap of Δ=0.5~1mm, The radial guide vanes 2 are not in contact with the end surface of the front shroud of the impeller 5 .

The radius r of the inner ring of the disc 1 is determined according to the inner diameter of the impeller 5 and the volute 4, the radius r is 1/2 of the diameter at the inlet of the impeller 5, and the radius R of the outer ring of the disc 1 is 1.5 to 2 of the radius r times, the height b of the disc 1 in the axial direction is 0.25 to 0.35 times the radius r.

The number of radial guide vanes 2 is determined according to the number of blades of the impeller 5 , which is one more than the number of blades of the impeller 5 .

The airfoil structure of the radial guide vane 2 is selected according to the hydraulic characteristics of different centrifugal pumps. The more commonly used airfoil types include RAF-6E airfoil and NACA airfoil.

Referring to Figure 2 and Figure 3, the blade length of the radial guide vane 2, that is, the chord length L of the airfoil is 1.9 to 2.2 times the radius r, and the axial height h of the radial guide vane 2 is 0.15 to 0.2 times the radius r times. The outlet placement angle β of the radial guide vane 2, that is, the angle between the tangent to the surface of the radial guide vane 2 and the tangent to the clockwise direction of the disc 1 is 60°-75°.

When the centrifugal pump is working, the prime mover drives the impeller 5 to rotate to do work on the fluid, converting the mechanical energy into the kinetic energy and pressure energy of the fluid, so as to realize the transportation of the fluid. During this process, most of the liquid will be discharged from the pump outlet, but a small part of the liquid will still flow out from the gap between the impeller 5 and the volute 4, resulting in volume loss. Therefore, the present invention is installed between the impeller 5 and the volute 4 to seal. When the impeller 5 rotates, it drives the liquid between the impeller 5 and the volute 4 to rotate, and the rotating liquid generates a directional flow under the pumping of the fixed airfoil radial guide vane 2, and the pumping direction is the same as that of the impeller 5 and the volute 4 The direction of movement of the leaked fluid is opposite, so as to prevent the fluid from leaking from the gap between the impeller 5 and the volute 4 and reduce the volume loss. At the same time, the present invention guarantees the good sealing performance of the centrifugal pump under the condition that the large axial clearance Δ=0.5-1mm, that is, the end surface of the front cover plate of the impeller 5 does not contact the disc 1 .

Claims (6)

1. a kind of centrifugal pump radial seal ring with airfoil type guide vane is assemblied in the spiral case (4) and impeller (5) of centrifugal pump Between, it is characterized in that：It is made of disk (1) and radial guide vane (2), in the side disk of disk (1) along the circumferential direction The uniform multiple radial guide vanes (2) of fixed and arranged, the appearance profile of the radial section of radial guide vane (2) is airfoil type.

2. a kind of centrifugal pump radial seal ring with airfoil type guide vane according to claim 1, it is characterized in that：Circle Disk (1) is fixedly connected on spiral case (4), and radial guide vane (2) faces impeller (5) and protects with the front cover plate end face of impeller (5) Hold Δ=0.5~1mm axial gap.

3. a kind of centrifugal pump radial seal ring with airfoil type guide vane according to claim 1, it is characterized in that：Circle 1.5~2 times, the axial direction that the inner radii r of disk (1) is the half of impeller (5) entrance diameter, outer radii R is radius r On height b be 0.25~0.35 times of radius r.

4. a kind of centrifugal pump radial seal ring with airfoil type guide vane according to claim 1, it is characterized in that：Diameter To guide vane (2) quantity than impeller 5 the number of blade more than one.

5. a kind of centrifugal pump radial seal ring with airfoil type guide vane according to claim 1, it is characterized in that：Diameter Airfoil type to guide vane (2) is RAF-6E aerofoil profile, NACA aerofoil profile.

6. a kind of centrifugal pump radial seal ring with airfoil type guide vane according to claim 1, it is characterized in that：Diameter Length of blade L to guide vane (2) is 1.9~2.2 times of radius r, the height h in axial direction is the 0.15~0.2 of radius r Again, outlet laying angle β is 60 °~75 °.