KR20190085790A - Sealing System of centrifugal pump - Google Patents

Abstract

The present invention relates to a centrifugal pump comprising: a case which includes an inlet, an outlet, and a storing space of an impeller; a bearing housing which is connected to a back side of the case; a rotating shaft which is supported by a ball bearing inside the bearing housing and receives driving force of a motor; and the impeller which is connected to an end part of the rotating shaft. The centrifugal pump comprises: a case cover which is detached from the case through a connecting member between the case and the bearing housing and supports the rotating shaft; and a bleed bushing sealing mechanism (BBSM) system which is positioned inside the case cover and seals a part of the rotating shaft. The BBSM system includes a bushing which seals a part of the outer circumference surface of the rotating shaft, a labyrinth seal which is provided in one part of the outer circumference surface of the bushing, and a return rotor which is integrally provided in the outer circumference surface of the bushing. The BBSM system includes little abrasion by preventing direct touch with the rotating shaft and a sleeve and eliminates the necessity of a cooling system by preventing generation of frictional heat of a sealed cross surface. The BBSM system reduces maintenance costs by facilitating semi-permanent use without replacing a component and facilitating an unmanned operation, and prevents resin contamination by minimizing leakage in a structure.

Description

Sealing System of Centrifugal Pump

The present invention relates to a centrifugal centrifugal pump, and more specifically, to a centrifugal centrifugal pump, a BBSM system (Bleed Bushing Sealing Mechanism), which is a device for sealing a rotary shaft by balancing pressure instead of a sealing system, , And a centrifugal centrifugal pump for securing reliability.

Generally, a centrifugal pump is a device for discharging a fluid having a pressure and velocity energy increased by a centrifugal force due to the rotation of the impeller at a high pressure / high speed by introducing the fluid into the case where the rotating space of the impeller is ensured.

With such an apparatus, Patent Document 1 discloses a general centrifugal centrifugal pump, which comprises a case constituting a centrifugal pump body, a grand packing and a ground which are sandwiched between a bearing housing and a middle portion of the case cover to support the shaft, A shaft to which the driving force is transmitted, and an impeller which is integrally assembled to the front end of the shaft and discharges the fluid introduced into the case toward the inlet port and the impeller.

In the centrifugal centrifugal pump described above, the rotational force transmitted to the shaft through the motor rotates the impeller. In the case provided with the intake port, the discharge port and the receiving space for the impeller, the central portion is vacuumed by the rotation of the impeller. At this time, the fluid, which is centrifugally driven by the rotation of the impeller, flows out between the case and the case cover and is discharged to the outside through the discharge port.

One of the biggest causes of failure in a centrifugal pump is a centrifugal pump having a structure that prevents the fluid passing through the centrifugal pump from leaking to the external environment as the fluid leaks to other components other than the impeller and the centrifugal pump To this end, various sealing means are conventionally provided on the rotational axis behind the impeller to prevent axial leakage of the fluid, and have sealing means such as a gland and a grand packing.

The sealing means, such as the gland packing, serves to prevent a part of the fluid flowing into the impeller from escaping to the rear of the impeller through the micro gap to the rotating shaft of the impeller.

However, the circumference of the rotary shaft is surrounded by the gland, the gland packing is forcedly inserted into the gaps, and the gland packing is compressed in the axial direction so that the packing and the rotary shaft are brought into close contact with each other and the gland is fastened with fastening means such as bolts. As the service period expires, the wear of the packing and the wear of the sleeve surrounding the rotating shaft are issued, and fluid leakage is liable to occur.

In addition, when the pressure of the fluid in the centrifugal pump acts at a high pressure / high speed, the damage of the sealing means and the rotary shaft becomes worse by the pressure of the fluid. Therefore, in order to continuously maintain the sealing state, There is a problem that it is necessary to tighten the fastening means such as a bolt from time to time or perform periodical replacement and maintenance work.

Also, since the structure of the packing itself always causes a certain amount of leakage, the maintenance cost is high, and the grease or oil impregnated in the gland packing causes water pollution, and the leakage problem of the fluid is important in the performance of the centrifugal pump There is a problem of failure of the centrifugal pump due to leakage of the fluid passing through the impeller due to a slight gap in the axial direction between the rotary shaft and the case cover.

Therefore, the thread which is commercially used in the centrifugal pump is largely divided into a gland packing seal and a mechanical seal. The gland packing chamber is formed by forcing the packing into the gap between the rotary shaft and the stuffing box (Pressure is applied by pushing hardly into a narrow hole or groove), and the friction is sealed. As the use period elapses, wear of the packing, wear of the rotary shaft or sleeve occurs, and leakage increases. Maintenance such as replacement is necessary.

At this time, the grease or oil impregnated into the grand packing chamber has many problems in the environmental standard that becomes corroded due to corrosion of the seal, water pollution, and the like, and since there is a certain amount of leakage in the operation of the grand packing chamber, It is serious to environmental pollution.

In addition, the mechanical seal is provided by complementing the disadvantages of the above-mentioned grand packing chamber, and it is possible to prevent leakage of the liquid under pressure from the centrifugal pump to the outside, or to prevent the air from being introduced into the centrifugal pump valve and slide bearings. However, the product price is more than 10 times higher than that of the grand packing seals. Therefore, it should be used in a limited manner, and troubles (repetitive start and stop shocks, It is impossible to operate the centrifugal pump completely. It is difficult to operate the centrifugal pump such as a water purification plant or a hydraulic pressure pump, and it is difficult to operate the centrifugal pump at all times, It is necessary.

KR 20-1999-0022727U

In order to solve the above-mentioned problems, the present invention is a new sealing system in which a return rotor is attached to a rotary shaft of a centrifugal centrifugal pump and a return rotor rotates and pressure is applied between a rotary shaft and a case to prevent leakage. BBSM system (Bleed Bushing Sealing Mechanism), which guarantees excellent performance as well as installation and maintenance cost, is applied by centrifugal centrifugal pump so that it does not come into direct contact with the rotating shaft or sleeve, It is possible to use semi-permanently and unattended operation because it does not need a cooling system and it does not need to replace parts, thus it is possible to reduce maintenance cost and minimize leakage of structure to prevent resin contamination It is an object of the present invention to provide a centrifugal centrifugal pump.

According to an aspect of the present invention, there is provided an air conditioner comprising: a case having a suction port, a discharge port, and an accommodation space for an impeller; A bearing housing connected to the rear of the case; A centrifugal pump supported by a ball bearing inside the bearing housing to receive a driving force of a motor and an impeller connected to an end of the rotary shaft, the centrifugal pump being detachably coupled to the case through a fastening member, A case cover for supporting the rotating shaft; And a BBSM system positioned inside the case cover to seal a portion of the rotary shaft, wherein the BBSM system includes a bushing for sealing a part of an outer circumferential surface of the rotary shaft, and a labyrinth seal member provided at a portion of an outer circumferential surface of the bushing And a return rotor integrally provided on an outer circumferential surface of the bushing.

Here, the case cover may include a first bypass for recirculating a part of the flow rate introduced into the inlet side of the BBSM system to the inside of the case, a second bypass for recirculating a part of the flow rate passing through the return rotor to the inside of the case, Path.

The bushing is divided into a first bushing and a second bushing on the front and rear sides along the rotation axis with respect to the return rotor. The first bushing is installed to have a gap from the outer circumferential surface of the rotation shaft, And the labyrinth seal chamber is spaced apart from the outer circumferential surface of the rotary shaft by a plurality of sealing rings in the longitudinal direction.

By providing the present invention constructed as described above, there is no need to provide a cooling system because there is almost no abrasion due to no direct contact with the rotating shaft or sleeve, no frictional heat is generated at the sealing end face, It is possible to reduce the maintenance cost and minimize the structural leakage, thereby preventing the resin contamination.

1 is a view showing a centrifugal centrifugal pump according to the present invention.
2 is a view showing a BBSM system applied to a centrifugal centrifugal pump according to the present invention;
3 is a diagram illustrating a numerical model of a shaft applied to a centrifugal centrifugal pump according to the present invention.
4 is a graph showing the mass flow rate change in the centrifugal centrifugal pump according to the present invention through the BBSM system.
5 is a pressure distribution diagram for various thicknesses and lengths of a centrifugal centrifugal pump according to the present invention through a BBSM system.
6 is a model diagram of an optimal thickness for a BBSM system in a centrifugal centrifugal pump according to the present invention.
Figures 7 (a), 7 (b) and 7 (c) are model views of a BBSM system in a centrifugal centrifugal pump according to the present invention.
FIG. 8 is an illustration of a mesh model through calculation of a BBSM system applied to a centrifugal centrifugal pump according to the present invention; FIG.
9 is a model view of an impeller applied to a centrifugal centrifugal pump according to the present invention.
10 is a detailed view showing the numerical difference of the impeller and the case applied to the centrifugal centrifugal pump according to the present invention.
11 is an experimental view showing a velocity vector in an impeller applied to a centrifugal centrifugal pump according to the present invention.
FIG. 12 is a diagram illustrating an example of a geometric position design of a BBSM system applied to a centrifugal centrifugal pump according to the present invention; FIG.
13 (a), 13 (b) and 13 (c) are pressure data graphs at the inlet pressure of 71,610 Pa of the BBSM system applied to the centrifugal centrifugal pump according to the present invention.
Figs. 14 (a), 14 (b) and 14 (c) are pressure data graphs obtained when the inlet pressure of the BBSM system applied to the centrifugal centrifugal pump according to the present invention was 18,889 Pa.
15 (a), (b) and (c) are graphs of pressure contours according to the inlet pressure 71,610 Pa of the BBSM system applied to the centrifugal centrifugal pump according to the present invention.
16 (a), 16 (b) and 16 (c) are graphs of pressure contours according to the inlet pressure of 18,889 Pa of the BBSM system applied to the centrifugal centrifugal pump according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

The centrifugal centrifugal pump (100) of the present invention comprises a case (110) having a suction space (111), a discharge port (112) and a space for accommodating the impeller (120); A bearing housing 130 connected to the rear of the case 110; A rotating shaft 150 which is supported by ball bearings in the bearing housing 130 to receive a driving force of the motor and an impeller 120 connected to an end of the rotating shaft 150.

A case cover 140 detachably coupled to the case 110 through a fastening member and supporting the rotation shaft 150 is provided between the bearing housing 130 of the case 110, And a BBSM system 160 that is positioned inside of the rotating shaft 150 and seals a portion of the rotating shaft 150.

At this time, the BBSM system 160 includes a bushing 161 for sealing a part of the outer circumferential surface of the rotary shaft 150; A labyrinth seal chamber 163 provided at a portion of an outer circumferential surface of the bushing 161; And a return rotor 165 integrally provided on the outer circumferential surface of the bushing 161.

The case cover 140 includes a first bypass 141 for recirculating a part of the flow rate of the fluid flowing into the inlet of the BBSM system 160 to the inside of the case 110, And a second bypass 143 for recirculating a part of the flow rate to the inside of the case 110.

The bushing 161 is divided into a first bushing 161a and a second bushing 161b on the front and rear sides along the rotation axis 150 with respect to the return rotor 165, And the second bushing 161b is installed to have a clearance with the outer circumferential surface of the rotary shaft 150. The labyrinth seal chamber 163 is provided with a plurality of sealing portions 161a, 164 formed at intervals along the longitudinal direction.

The BBSM system (Bleed Bushing Sealing Mechanism) applied to the centrifugal centrifugal pump 100 of the present invention is characterized in that a return rotor 165 is attached to the rotary shaft 150 of the centrifugal centrifugal pump 100, and the return rotor 165 rotates Is a new sealing system that prevents leakage of the flow by applying pressure between the rotary shaft 150 and the case 110. [

1 and 2, the shape and the flow field of the BBSM system 160 are located at a distance of 33.5 mm from both suction ends of the volute centrifugal centrifugal pump 100 in the form of a cylinder having a diameter of 70 mm. The centrifugal centrifugal pump 100 And serves as a sealing member for blocking water leaked from the water.

The return rotor 165 rotates at 1,750 RPM at the same speed as that of the centrifugal pump 100 because the boss 161 and the case 110 of the BBSM system 160 are rotated about the rotation axis The frictional heat of the sealing section is not generated because the gasket 150 is not directly in contact with the sealing member 150.

Therefore, it has a strength that a cooling system is not required, and it can be an eco-friendly room which can prevent water pollution in advance without requiring a lubricant in terms of structure.

In other words, the shape of the BBSM system 160 is largely divided into three parts: bushing, a return rotor, and a labyrinth seal.

That is, the bushing 161 of the fluid inlet, the return rotor (composed of eight blades) at the middle portion, and the labyrinth chamber 163 of six Teeth at the bottom constitute the entire system of the BBSM system 160.

A bypass located in the return rotor 165 and the labyrinth seal chamber 163 and having a bypass located in the return rotor 165 is connected to the labyrinth seal chamber 163 through the first bypass 141, By the second bypass 143, as shown in FIG.

Here, a part of the flow rate flowing into the inlet of the BBSM system 160 is recirculated into the centrifugal pump 100 through the first bypass 141, and a part of the flow rate passing through the return rotor 165 is returned to the second And is designed to escape to the outside through the bypass 143 and the outlet.

That is, the inclination angle of the labyrinth seal 163 located at the end of the BBSM system 160 may vary depending on the shape of the labyrinth seal 163, which may cause a decrease in the maximum leakage amount.

The numerical values of the present invention are based on the governing equations for the analysis.

Continuity equation

(3.1.1)

(3.1.1)

Momentum equation

(3.1.2)

(3.1.2)

는 밀도,

,

,

는 x, y, z방향의 속도 성분이다.Based on continuous equations and equations of motion, where

The density,

,

,

Is the velocity component in the x, y, and z directions.

의 지배방정식 또는 SST (Shear Stress Transportation) 모델

의 지배방정식로 구분된다.And the turbulent model governing equations are the standard model

Of the governing equation or SST (Shear Stress Transportation) model

And so on.

의 지배방정식은 BBSM시스템(160)에 대한 유동해석에서는 회전체의 난류현상과 전단력에 의한 영향을 고려하기 위하여, 레이놀즈 응력이 지배적인 내부의 갇힌 유동해석에 적합하여 일반 유체유동에 흔하게 적용되는

난류모델을 사용하였다.

모델은 가장 일반적인 난류모델 중에 하나로서 난류 에너지의 대류와 확산의 효과를 나타내기 위해 2개의 전송 방정식을 추가로 포함하고 있는 two-equation model이다. 본 연구에서 사용된 표준

모델은 난류운동에너지

에서 특성속도를, 난류운동에너지 소산율

에서 특성길이를 구하여 난류점성계수

를 계산하는 모델이며, 유체가 비압축성인 경우에

와

은 다음의 수송방정식에 의해서 결정된다.First, the standard model

The governing equations of the BBSM system 160 are suitable for the analysis of trapped flows dominated by Reynolds stresses in order to take into account turbulence and shear force effects of the rotating body in the flow analysis,

Turbulence model was used.

The model is one of the most common turbulence models and is a two-equation model that additionally includes two transmission equations to show the effect of convection and diffusion of turbulent energy. The standard used in this study

The model uses turbulent kinetic energy

, The turbulent kinetic energy dissipation rate

And the turbulent viscosity coefficient

If the fluid is incompressible,

Wow

Is determined by the following transport equation.

방정식

equation

(3.1.3)

(3.1.3)

방정식

equation

(3.1.4)

(3.1.4)

(

=1, 2, 3)는

방향의 속도 구성성분이고

는 압력,

는 유체의 밀도,

는 생성항으로서 다음과 같이 정의할 수 있다.here

(

= 1, 2, 3)

Direction velocity component

Pressure,

Is the density of the fluid,

Can be defined as follows.

(3.1.5)

(3.1.5)

는 물성치가 아니라 난류운동의 양상이나 이력에 따라 변하는 값이다. 이 난류점성계수는 실험이나 고찰로부터 난류운동의 특성길이와 특성속도에 의해 결정되는 값으로 알려져 있으며, 이를 표현하면 다음과 같다.Turbulent viscosity coefficient

Is not a property value but a value that changes according to the aspect or history of the turbulent motion. This turbulent viscosity coefficient is known to be determined by the characteristic length and characteristic velocity of the turbulent motion from the experiment or observation.

(3.1.6)

(3.1.6)

The model constants used in the calculations are defined as follows.

의 지배방정식은 BBSM시스템(160) 입구 경계조건에 적용될 원심펌프(100) 해석에서 난류 모델은 벽면에서의 해석에 장점을 가지고 있는 SST

난류 모델을 사용하였다. SST(Shear Stress Transportation) 난류 모델은

모델과

모델의 장점을 결합한 모델로서, 벽 근처에서는

모델이 사용되고

보다 정체구역의 난류 증진을 고려할 수 있도록 고안되어 있어 원심펌프(100)와 같은 회전체에서 국소적인 난류 작용을 파악하는데 이점이 있다.

모델은

에서 난류운동에너지를

에서 특성소산을 구하여 계산되는 two-equation 방정식으로서

모델에 비해 낮은 레이놀즈수 영역에서 벽면 근처에서의 유동을 잘 처리하는 모델이다. SST 모델에서

와

항을 다음과 같이 정의한다.Second, the SST (Shear Stress Transportation) model

The governing equation of the centrifugal pump (100) to be applied to the inlet boundary conditions of the BBSM system (160) is the SST

Turbulence model was used. SST (Shear Stress Transportation) turbulence model

Model and

A model that combines the advantages of a model,

The model is used

And it is advantageous to grasp the local turbulence action in the rotating body such as the centrifugal pump 100. [0054]

The model

Turbulent kinetic energy in

As a two-equation equation calculated from the property dissipation in

This model handles near-wall flow at low Reynolds number compared to the model. In the SST model

Wow

The term is defined as follows.

방정식

equation

(3.1.7)

(3.1.7)

방정식

equation

(3.1.8)

(3.1.8)

는 다음과 같다.Turbulent viscosity coefficient

Is as follows.

(3.1.9)

(3.1.9)

,

,

, 는 다음과 같이 정의한다.The auxiliary equations in equations (3.2.1) to (3.2.3)

,

,

, Is defined as follows.

(3.1.10)

(3.1.10)

(3.1.11)

(3.1.11)

(3.1.12)

(3.1.12)

는 다음과 같이 나타낸다.(1.5) The auxiliary equation of the equation

Is expressed as follows.

(3.1.13)

(3.1.13)

,

,

,

는 다음의 상관관계식에 의해 새로운 계수

,

,

,

로 교체된다. (3.1.7), (3.1.8) The coefficient of the equation

,

,

,

By the following correlation equation:

,

,

,

.

(3.1.14)

(3.1.14)

The initial coefficient values are as follows.

,

,

,

,

,

,

,

,

,

,

,

,

,

,

은 다음과 같이 결정되며,

(3.1.9)의

는 변형률을 나타낸다.Coefficient

Is determined as follows,

(3.1.9)

Represents the strain.

Therefore, a gap, which is one of the portions expected to affect the pressure rise in the designing step of the shape of the BBSM system 160, should set a gap between the bushing 161 and the rotary shaft 150, You need to do a preliminary analysis to get it.

On the contrary, the gap thickness range is set to 0.1 mm to 0.5 mm, and the length of the bushing 161 in the direction of the rotation axis 150 is shaped as 117 mm and 225 mm, respectively. Respectively.

If CFD analysis is performed under the same condition as [Figure 1], the pressure distribution as shown in [Figure 2] can be obtained.

[Figure 1] Conceptual diagram and 3D model for CFD seawater for centrifugal pump

It is a system to prevent leakage by the pressure (62kPa) raised by the rotation of [Figure 2].

[Figure 2] CFD analysis of the shaft sealing device for centrifugal pump, pressure distribution

Such a system for preventing water leakage due to the rotation of the rotor will lose its effect if the rotor does not rotate because the pump does not operate, and a device for preventing the leakage will be required.

[Figure 3] is a device that prevents leakage by contact when the pump is stopped and extends the lifetime by blocking the damage caused by rotating friction by pushing it to a higher pressure as shown in [Figure 2] during pump operation.

[Figure 3] Device to prevent leakage when stopping pump

[Figure 4], [Figure 5], and [Figure 6] are various types of devices applying the concept of [Figure 3].

[Figure 4] is a shape in which the spring and the contact material (such as wood rubber synthetic resin carbon white metal) are divided. In the case of a spring, it can be replaced by a flexible O-ring.

[Figure 4] Device to prevent water leakage (No. 1)

In the case of [Fig. 5], the sheet packing of flexible material is pulled out to the rotor area to prevent leakage during non-operation and to prevent damage due to rotation due to folding during operation.

[Figure 5] Device to prevent leakage when stopping pump (No. 2)

[Figure 6] is an O-ring type using rubber and elastic material. It prevents leakage due to contact when stopping O-ring and increases wear due to centrifugal force and increased pressure during operation.

[Figure 6] Device to prevent water leakage (No. 3)

Therefore, CFD analysis was performed with CFX V16.2 by generating approximately 480,000 hexahedra and prism lattices using ICEM CFD V16.2 under the above conditions.

In Figure 3, pressure is applied to the inlet boundary conditions (inlet) of 0.65 MPa and atmospheric pressure (0.1 MPa) to the outlet conditions. Table 1 shows the average area of mass flow rate at the outlet And it can be confirmed that the outlet flow rate increases as the gap thickness increases from 0.1 mm to 0.5 mm.

[Table 1] Mass flow rate according to thickness

That is, FIG. 4 is a graphical representation of the flow rate according to the gap thickness corresponding to the created [Table 5]. Table 2 shows the outlet flow rate along the length. When the length of the bushing 161 is compared with 173 mm and 225 mm, the flow rate of the outlet at 225 mm is measured to be small. This confirms that the length affects the flow rate at the outlet. [Table 1] and [Table 2] show that the outlet flow rate is proportional to the thickness of the gap and inversely proportional to the length.

[Table 2] Mass flow rate change with length

On the other hand, according to FIG. 5, the pressure distribution diagram for the result of the flow analysis according to the gap thickness is shown. The pressure at the inlet is lowered toward the outlet and is evenly distributed. The purpose of the gap analysis is to minimize the gap between the seals and reduce leakage by applying resistance to the flow of leaked hydraulic fluid. A frictional force is generated between the case 110 and the rotary shaft 150 due to the narrow thickness of the gap and the length in the direction of the rotary shaft 150. As a result, Therefore, if the thickness of the gap is reduced to the maximum and the length in the direction of the rotating shaft 150 is designed to be long, the outlet flow rate can be minimized.

In recent years, the gap of the shape of the BBSM system 160 has been reduced to 0.175 mm (total 0.35 mm) which is the minimum design point proposed by API 610 (ISO 13709) ) Was applied as shown in FIG.

Therefore, the analytical model is divided into three types in an optimal shape and shaped to compare the results with respect to the presence or absence of the bypass and return rotor 165. 7A is a schematic view showing a state in which the bushing 161, the return rotor 165, the labyrinth seal chamber 163 and the return rotor 165 attached to the labyrinth seal chamber 163 and the return rotor 165 as draft shapes of the BBSM system 160 The first bypass 141 and the second bypass 143 are present and the flow rate of the first bypass 141, the second bypass 143, and the flow rate exiting the outlet through the flow analysis It can be confirmed quantitatively.

7B shows a state in which the return rotor 165, the first bypass 141 and the second bypass 143 are removed from the shape shown in FIG. 7A and the labyrinth seal 163 alone is provided, The inlet / outlet flow rate of the inlet / outlet port 160 can be confirmed.

That is, the role of the labyrinth seal 163 can be confirmed by removing the return rotor 165, and the pressure generated in the return rotor 165 through the comparison of (c) with the return rotor 165 The effect of the increase on the BBSM system 160 can be confirmed.

7 (c) shows a flow field. The shape of the flow path is composed of a bushing 161, a return rotor 165, and a labyrinth seal 163. The first bypass 141, the second bypass 143) is removed. the role of the return rotor 165 can be confirmed by comparing the results of the analysis of (a) and (b).

On the other hand, in the case of grid generation, the grid system of the BBSM system 160 is constructed using ICEM CFD V16.2, and the grid system generated in the model is shown in FIG.

Since the gap between the inlet and the bushing 161 is very thin, the lattice structure of the portion of the bushing 161 is formed of hexa which is a block alignment grating system. This is a grid system that combines the merits of an orthogonal grid, which is easy to solve, and the function of a curved grid to solve complicated curve boundaries.

Accordingly, since the shapes of the return rotor 165 and the labyrinth seal chamber 163 are complex, an unstructured grating system is used to generate a large number of small gratings. This is the most common type of lattice arrangement for complex shapes, tetra and prism.

[Table 3] shows the number of grids used in the flow analysis of the BBSM system 160, and the total number of nodes used in the grid is 3,321,200. The lattice of the bushing 161 was composed of about 200,000 nodes and 180,000 elements. The gratings of the return rotor 165 and the labyrinth seal 163 consisted of about 3.1 million nodes and 1.3 million elements. According to the case 110, although the number of gratings is different, they are created with similar nodes and elements. In addition, by increasing the number of nodes, about 4.5 million nodes and about 5 million grid sensitivity are performed, thereby improving the reliability of the grid.

[Table 3] CFD analysis of mesh information of bushing, return rotor, labyrinth seal area

The flow analysis of the centrifugal centrifugal pump 100 for obtaining the boundary condition of the BBSM system 160 applied to the present invention is based on the fact that the impeller in the centrifugal pump 100 has a great influence on the performance of the centrifugal pump 100 Therefore, the hydrodynamic knowledge is required for the design and analysis of the impeller 120. The case 110 of the centrifugal pump 100 effectively transforms the centrifugal force received from the impeller 120 into pressure energy and the radial thrust force acting on the shaft 110 Force). In designing the circulation system using the centrifugal pump 100, if the size and shape of the pump suction pipe and the suction water tank of the centrifugal pump 100 are not properly designed, It is not sucked smoothly, and vortices (vertex) and swirl are generated in the suction water tank.

9 shows the shape and flow field of the balun centrifugal pump 100 on the inlet 111 side and the centrifugal pump 100 to be analyzed has a structure in which the centrifugal centrifugal pump 100 on the inlet 111 side is divided into six impellers 120 . The lattice generation of the centrifugal pump 100 was performed using ANSYS ICEM CFD V16.2.

As shown in FIG. 10, the lattice of the centrifugal pump 100 is generated, and the lattice is generated by mixing a hexagonal lattice and a tetrahedra lattice, and a prism layer is formed on the wall lattice, Respectively. The total number of grids was 2,328,649, and the reliability of the grating was improved by performing about 4,700,000 lattice sensitivities by doubling the number of nodes.

In the case of numerical analysis, the model of the centrifugal pump 100 analyzed to obtain the boundary conditions of the BBSM system 160 is a centrifugal centrifugal pump 100 at the suction port 111 side and the shape of the centrifugal pump 100 Since the flow is symmetrical, a half model is formed based on the global coordinate system xy plane, and the flow is analyzed by applying a symmetry boundary condition (symmetry).

This is because the symmetric boundary condition in 3D is used when the shape and the flow field are necessarily symmetric and can be defined only when the flow is parallel to the symmetry plane and the vertical component gradient is zero.

Atmospheric pressure (1 atm) was applied at the inlet boundary condition, and at the exit boundary condition, the performance curves of 1,750 rpm and 5 mass flow rates (150 m3 / hr, 300 m3 / hr, 450 m3 / hr, 600 m3 / hr, 750 m3 / hr) was applied to the centrifugal pump (100).

On the other hand, the working fluid is water (25 ° C) at room temperature. The domain is a rotating rotor (a frozen rotor is used as an interface technique for dividing the impeller into a case and connecting domains).

모델 기반의 SST 모델을 적용하였다. SST 모델은

모델과

모델의 장점만을 살린 모델로, 벽면 근처에서는

모델 방식으로 계산을 진행하고, 자유흐름 영역에서는

모델 방식으로 계산을 수행한다. 또한 SST 모델의 경우 천이영역에서의 유동 특성도 고려할 수 있기 때문에 최근 많이 사용되는 모델이다.Therefore, the convergence judgment is the time when the sum of the residual terms becomes 10-5 or less, and the turbulence model of the flow analysis

Model - based SST model was applied. The SST model

Model and

Model that only takes advantage of the model, near the wall

In the free flow region,

Perform calculations in a model way. In addition, the SST model is a popular model since it can consider the flow characteristics in the transition region.

11, the results of the flow analysis of the centrifugal pump 100 of the present invention are the vector results of the flow analysis of the centrifugal pump 100 and the results of the flow analysis of the centrifugal pump 100 Power and lift of the centrifugal pump 100 according to the flow rate conditions (150 m3 / hr, 300 m3 / hr, 450 m3 / hr, 600 m3 / hr, 750 m3 / hr) The analysis results to be applied to the inlet boundary conditions of the BBSM system 160 correspond to the centrifugal pump 100 at flow rates of 150 m3 / hr and 560 m3 / hr and correspond to the positions of the BBSM system 160 at the CFD-Post And applied to the inlet boundary conditions of the BBSM system 160. [0064]

[Table 4] Pump performance according to the mass flow rate change of the pump

Also, the flow analysis for the performance evaluation of the BBSM system 160 as the boundary condition of the BBSM system 160 integrates the governing equation of the fluid flow for all inspection volumes in the region using ANSYS CFX V16.2, (RMS) values of the iterative variables to obtain the solution of the solution are calculated to converge to 10 -5 or less. In this case, the imbalance value of the energy and mass in the calculation region is set to be less than 0.1%. As described above, the turbulence model of the flow analysis employs the k-epsilon model, which utilizes the advantages of the k-epsilon model to reduce the back flow of the rotating centrifugal pump 100 and limit the amount of leakage through the seals .

Therefore, the boundary conditions for the flow analysis of the BBSM system 160 as shown in FIG. 7, which introduces the shape of the boundary condition, are also schematically illustrated. The domain for the flow analysis is divided into the return rotor 165 and the stator, The Frozen-Rotor technique is applied to the interface between the two.

This is a boundary condition in which a counter-wall is applied so that the wall of the case 110 does not rotate because only the return rotor 165 rotates in the three-dimensional flow field.

That is, a GGI (General Grid Interface) connection technique can be applied as a boundary condition for conveying the flow information to the two regions among the flow analysis methods simultaneously including the rotation / fixed region, so that one of the BBSM system 160 (1 atm) of 25 ° C air, and sets the exit area to be the sealing area, and the return rotor of the BBSM system (160) (165) region is set to rotate at 1,750 RPM, which is the same rotational speed as the centrifugal pump (100) boundary conditions.

12, the position of the BBSM system 160 is located at a distance of about 33.5 mm from the both suction portions of the centrifugal centrifugal pump 100, the diameter of the area of the inlet contact is 70 mm, After the flow analysis of the centrifugal pump 100 to extract the pressure, the pressure is derived by averaging the mass of the face at the location of the inlet of the BBSM system 160 using CFD-Post V16.2.

That is, the pressure corresponding to 560 m3 / hr and 150 m3 / hr of the rated conditions of the centrifugal pump 100 flow analysis result of the present invention is applied as the inlet boundary condition of the BBSM system 160 as shown in Table 5, The boundary condition between the outlet of all the cases 110 and the first bypass 141 and the second bypass 143 of (a) was set at atmospheric pressure (1 atm).

[Table 5] Analysis conditions for the BBSM system

As a result, the flow analysis results are as follows. First, the flow rate at the inlet, the first bypass 141, the second bypass 143, and the outlet of the BBSM system 160 is analyzed after the flow analysis.

Table 6 shows the flow rates of (a), (b), and (c) under the conditions of the centrifugal pump 100 (A, 71,610 Pa).

In this case, the symbol + denotes a numerical value input into the BBSM system 160, and the symbol - denotes a numerical value which is exited from the BBSM system 160 to the outside.

(a) shows a flow rate of 0.2066 kg / s to the inlet, 0.1794 kg / s of 50% or more to the first bypass 141, 0.0134 kg / s to the second bypass 143 and 0.0134 kg / s. At this time, the sum of the flow rate to the BBSM system 160 by the mass conservation law is the same.

In case (b), 0.0973 kg / s is input at the inlet, which is smaller than the inlet flow of (a). Since bypasses other than the outlet are removed, the flow of 0.0973 kg / s is exited to the exit.

(c) has a flow rate of 0.0898 kg / s at the inlet, which is smaller than the inlet flow rate of (a) and (c). The outlet flow rate is 0.0898 kg / s, which is the same value as the inlet flow rate.

[Table 6] Mass flow rate numerical results of BBSM inlet pressure at 71,610 Pa

Table 7 shows the flow rates of (a), (b), and (c) under the condition of centrifugal pump 100 B (18,889 Pa).

In this case, the symbol + denotes a numerical value input into the BBSM system 160, and the symbol - denotes a numerical value which is exited from the BBSM system 160 to the outside. The condition of the centrifugal pump (100) B has a lower flow rate than that of the condition A because the pressure is lower than that of A.

(a) shows a flow rate of 0.1387 kg / s at the inlet and 0.119 kg / s of 50% or more is discharged to the first bypass 141, 0.0096 kg / s to the second bypass 143 and 0.0092 kg / s. The sum of the flow rate into and out of the BBSM system 160 is equal.

(c) flows at 0.0472 kg / s through the inlet and 0.0472 kg / s through the bypass outlet.

(a), (b) and (c), it can be confirmed that the smallest flow rate is B (18,889 Pa) in (a). It is considered that the overall volume performance of the centrifugal pump 100 needs to be considered in view of the fact that the inlet flow rate is larger than that of the other case 110. [ This is because the amount of water flowing into the inlet of the BBSM system 160 escapes from the centrifugal pump 100 and the amount thereof influences the flow rate of the centrifugal pump 100.

(c) and (c) are compared and it is confirmed that the flow rate at the inlet and the outlet of (c) with the return rotor 165 is small. It is considered that the effect of (c) with return rotor 165 is better in comparison with (c) in terms of leakage amount.

Therefore, from the viewpoint of reducing the leakage amount, the performance of (a) having the smallest outlet flow rate is high, and the performance of (c) is high in terms of a small flow rate flowing into the inlet.

Also, if the inlet pressure used for the boundary condition is high, the pressure difference with the outlet is high, and it is confirmed that the inlet / outlet flow is large. The flow rate of the outlet of the condition (71,610 Pa) of A in all the cases 110 flows more than the outlet flow rate of the condition of B (18,889 Pa). It is necessary to always consider the state where the pressure applied to the centrifugal pump 100 suction portion (the position of the BBSM system 160) is highest.

[Table 7] Mass flow rate numerical results of BBSM inlet pressure at 18,889 Pa

13, the pressure distribution comparison is performed in the longitudinal direction (x) of the BBSM system 160 in the analysis results of (a), (b) and (c) using the conditions of the centrifugal pump 100 And the pressure (y) along the line is measured and plotted.

(a) It is expected that the suction action has occurred due to the tendency of the gauge pressure to drop to negative pressure at 60 to 80 mm corresponding to the position of the first bypass 141 of the graph.

That is, the pressure of the lowered fluid passing through the first bypass 141 is increased by the return rotor 165 and is stably reduced toward the outlet, and the position of the first bypass 141 is reduced into the centrifugal pump 100 The optimal position of the first bypass 141 in the centrifugal pump 100 should be selected so that suction does not occur in the BBSM system 160 and the influence of the negative pressure greatly occurs.

(b) In the graph, the slope of the pressure curve increases at a position of 130 to 140 mm in the direction of the rotational axis 150 of the BBSM system 160 because the pressure is increased by the resistance received by the teeth of the labyrinth . As shown in the graph in (c), the high pressure at the inlet gradually decreases, and the return rotor 165 ) Is converted into pressure energy and it is judged that the pressure is increased.

14, the pressure (y) along the longitudinal direction (x) of the BBSM system 160 is measured and applied to the centrifugal pump 100 (100) B (18,889 Pa) ) A condition results.

(c) It can be seen from the graph that the pressure generated at the return rotor 165 is higher than the pressure generated at the inlet, and thus it can be confirmed that the pressure of the return rotor 165 affects the flow rate to the inlet . It is believed that the pressure generation of the return rotor 165 serves to prevent leakage of the flow to the inlet of the BBSM system 160.

FIGS. 14 and 16 show pressure distributions for all the cases 110. FIG.

Here, the condition (a) of the centrifugal pump 100 A is that the pressure of 0 Pa is distributed because the water is sucked into the centrifugal pump 100 through the first bypass 141. (c), a pressure due to rotation is generated in the return rotor 165 as confirmed in the graph.

In the condition (c) of the centrifugal pump 100 B, the pressure generated in the return rotor 165 is higher than the pressure in the inlet. It can be confirmed that the pressure in the return rotor 165 rises high through the pressure distribution of the centrifugal pump 100 (A) and the centrifugal pump B (c).

The conclusion is that the sealing mechanism for the BBSM system 160 is analyzed and the pressure rise caused by the return rotor 165 through the analysis results of (c) and (c) related to the presence or absence of the return rotor 165 And serves to push out the incoming flow at the entrance of the BBSM system (160).

(a), it can be confirmed that the outlet flow rate is the smallest under the condition of being recirculated to the centrifugal pump 100 through the bypass. The role of this bypass is evaluated as a relatively high efficiency efficiency in terms of reducing the leakage at the outlet, but creates a suction pressure in the bypass to increase the flow into the inlet of the BBSM system 160.

Therefore, it is considered that the overall performance of the centrifugal pump 100 will be negatively affected. To solve this problem, it is necessary to consider the optimal position of the bypass in the centrifugal pump 100, Is a draft-like shape that has not been validated for efficiency, so it is possible to maximize the effect of the pressure drop by designing the wing.

By providing the present invention configured as described above, there is almost no wear due to no direct contact with the rotating shaft 150 or the sleeve, frictional heat of the sealing section is not generated, and therefore, there is no need for a cooling system, It is possible to reduce the maintenance cost and minimize the leakage of the structure, thereby preventing the resin contamination.

The terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary terms. It should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the configurations shown in the drawings and the embodiments described herein are merely the most preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, It should be understood that various equivalents and modifications are possible.

100: Centrifugal centrifugal pump
110: Case
111: inlet
112:
120; Impeller
130: Bearing housing
140: Case cover
141: First bypass
143: Second bypass
150:
160: BBSM system
161: Bushing
163: labyrinth thread
165: Return rotor

Claims (3)

A case 110 having a suction port 111, a discharge port 112, and a space for accommodating the impeller 120; A bearing housing 130 connected to the rear of the case 110; A centrifugal pump 100 including a rotating shaft 150 supported by a ball bearing inside the bearing housing 130 to receive a driving force of a motor and an impeller 120 connected to an end of the rotating shaft 150,
A case cover 140 detachably coupled to the case 110 through a fastening member between the bearing housing 130 of the case 110 and supporting the rotating shaft 150; And
And a BBSM system 160 positioned inside the case cover 140 to seal a portion of the rotating shaft 150,
The BBSM system 160,
A bushing 161 sealing a part of the outer circumferential surface of the rotary shaft 150;
A labyrinth seal chamber 163 provided at a portion of an outer circumferential surface of the bushing 161;
And a return rotor (165) integrally provided on an outer circumferential surface of the bushing (161).
The method according to claim 1,
The case cover 140
A first bypass 141 for recirculating part of the flow rate introduced into the inlet of the BBSM system 160 to the inside of the case 110 and a second bypass 141 for returning a part of the flow rate passing through the return rotor 165 to the case 110 And a second bypass (143) for recirculating the gas to the inside of the second centrifugal pump (100).
The method according to claim 1,
The bushing (161)
The first bushing 161a and the second bushing 161b are divided into a front bushing 161a and a rear bushing 161b along the rotary shaft 150 with respect to the return rotor 165,
The first bushing 161a is installed to have a clearance with the outer circumferential surface of the rotary shaft 150,
The second bushing (161b) is installed to have a clearance with the outer peripheral surface of the rotary shaft (150), and the labyrinth seal chamber (163) is formed with a plurality of sealing rings (164) Centrifugal pump (100).

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