A Solving Method for the Balanced Position of the Journal of the Radial Sliding Bearing of a Dense-Phase CO2 Delivery Pump

Abstract

The present invention provides a method for solving the balance position of the journal of a radial sliding bearing of a dense-phase CO₂ transfer pump, including: constructing an oil film model of the radial sliding bearing to be studied and determining input parameters according to the oil film model; selecting and defining the inlet, wall surface, and outlet of the oil film model to perform mesh division on the oil film model; selecting steady-state solution in fluid simulation software and sequentially setting material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface, and solution method; performing initialization and the first calculation in sequence to obtain the oil film pressure distribution when the journal is at the initial position; setting output parameters; generating a series of design points in the experimental design module of response surface optimization and conducting corresponding experiments; generating a response surface based on the experimental results and performing optimization according to the response surface to obtain the balance position of the journal. The present invention comprehensively considers the influences of factors such as viscous heating, viscosity-temperature effect, multiphase flow, etc., is more consistent with the actual situation, and has high calculation accuracy.

Description

Technical Field

[0001] The present invention relates to the technical fields of booster pumps and hydrodynamic lubrication technology, and particularly to a method for solving the equilibrium position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump. Background Art

[0002] A dense-phase CO2 transfer pump can pressurize CO2 gas and transfer it in a dense phase. In the field of oil and gas exploration, injecting dense-phase CO2 into oil and gas wells can increase the oil recovery rate. In addition, it can also be widely applied in fields such as chemical engineering, food processing, and pharmaceuticals. A radial sliding bearing bears radial loads through the lubricating oil film formed between the journal and the bearing bush, thereby reducing friction and wear, and can be widely applied in heavy-duty rotating machinery such as dense-phase CO2 transfer pumps. The radial sliding bearing plays a crucial role in the operation of a dense-phase CO2 transfer pump, and its performance can significantly affect the operation accuracy, efficiency, and lifespan of the entire machine. Calculating the equilibrium position of the journal of a radial sliding bearing under specific rotational speeds and loads is a prerequisite for studying the performance of the entire dense-phase CO2 transfer pump. Therefore, accurately and quickly calculating the equilibrium position of the journal of a radial sliding bearing is of great significance for the research and application of dense-phase CO2 transfer pumps.

[0003] Existing technical solutions can be mainly divided into two types: one is to perform numerical calculations using programming languages such as Matlab and Python to obtain the equilibrium position of the journal of a radial sliding bearing; the other is to solve the equilibrium position of the journal of a radial sliding bearing by using commercial CFD software such as Fluent and UDF (user-defined function). The first solution is relatively complex to operate, requires a high level of mathematics and programming for the operator, and often introduces a large number of simplified assumptions, resulting in low calculation accuracy; the UDF used in the second solution often uses the idea of point-by-point scanning to find the equilibrium position of the journal, with low solution efficiency.

[0004] Therefore, how to accurately and quickly calculate the equilibrium position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a method for solving the equilibrium position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump, which can accurately and quickly calculate the lubrication performance of the radial sliding bearing when given rotational speeds and loads, so as to meet the requirements of the actual engineering applications of dense-phase CO2 transfer pumps.

[0006] To achieve the above purpose, the present invention provides the following solution:

[0007] A method for solving the equilibrium position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump includes:

[0008] Build an oil film model of the radial sliding bearing to be studied, and determine the input parameters according to the oil film model; the input parameters include the horizontal offset and vertical offset of the journal;

[0009] Select and define the inlet, wall surface and outlet of the oil film model to perform mesh division on the oil film model;

[0010] Select steady-state solution in the fluid simulation software, and sequentially set material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface and solution method;

[0011] Perform initialization and the first calculation in the fluid simulation software to obtain the oil film pressure distribution when the journal is at the initial position;

[0012] Set output parameters; generate a series of design points in the experimental design module of response surface optimization, and conduct corresponding experiments to obtain experimental results;

[0013] Generate a response surface based on the experimental results, and perform optimization according to the generated response surface to obtain the equilibrium position of the journal.

[0014] Preferably, the oil film model includes a thin film part between the journal and the bearing bush and a cylindrical part of the oil inlet; the diameter of the journal is 79.8 mm and the length is 100 mm; the diameter of the bearing bush is 80 mm and the length is 100 mm; the diameter of the oil inlet is 4 mm and the height is 5 mm.

[0015] Preferably, the initial value of the horizontal offset is set to 0.03 mm, and the initial value of the vertical offset is set to 0.04 mm.

[0016] Preferably, the mesh division of the oil film model includes:

[0017] Divide the thin film part into 720 equal parts in the circumferential direction, 250 equal parts in the axial direction, and 3 equal parts in the thickness direction, and divide the oil inlet into 40 equal parts in the circumferential direction and 20 equal parts in the height direction.

[0018] Preferably, when selecting steady-state solution in the fluid simulation software and sequentially setting material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface and solution method, it includes:

[0019] Set the liquid-phase material according to the used N32 lubricating oil, set the viscosity through UDF, introduce the viscosity-temperature effect, and set the gas-phase material for the lubricating oil vapor;

[0020] Select the Mixture model, select the liquid-phase material for the first phase, select the gas-phase material for the second phase, select the Schnerr-Sauer model in cavitation for mass transfer, and set the vaporization pressure to 30000 Pa;

[0021] Select the Laminar model and check Viscous Heating;

[0022] Set the operating pressure to 0 Pa;

[0023] Set the inlet gauge pressure to 120000 Pa and the temperature to 298.15 K. Set the outlet gauge pressure to 101325 Pa and the total return temperature to 298.15 K. Set the journal wall as a moving wall with a rotational speed of 3000 rpm and a heat flux of 0. Set the other walls as stationary walls with a heat flux of 0;

[0024] Set the bearing wall and the bottom surface of the oil inlet as the interface;

[0025] Select the Coupled format for the pressure-velocity coupling algorithm. For spatial discretization, select PRESTO! for the pressure format and first-order upwind for other flux formats. Set the number of iterations to 500. When the mass flow rate difference between the inlet and outlet is less than 1%, it is determined that the iteration converges.

[0026] Preferably, the initialization is a hybrid initialization.

[0027] Preferably, the output parameters include: the horizontal oil film force on the journal, the vertical oil film force, and the ratio of the horizontal oil film force to the vertical oil film force.

[0028] Preferably, generate a response surface based on the experimental results and optimize according to the generated response surface to obtain the equilibrium position of the journal, including:

[0029] Set the optimization objectives: the vertical oil film force is 4000 N, the ratio of the horizontal oil film force to the vertical oil film force is 0, and the tolerances are all 0.001;

[0030] Check "Verify candidate points" and calculate to obtain 3 candidate design points;

[0031] Select 1 candidate design point that is closest to the optimization objective, that is, the horizontal offset is 0.036977 mm and the vertical offset is 0.029228 mm. Verify that the corresponding vertical oil film force is 4010.7 N and the ratio of the horizontal oil film force to the vertical oil film force is -0.0026.

[0032] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0033] The present invention provides a method for solving the balance position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump, including: constructing an oil film model of the radial sliding bearing to be studied, and determining input parameters according to the oil film model; the input parameters include the horizontal offset and vertical offset of the journal; selecting and defining the inlet, wall surface and outlet of the oil film model to perform mesh division on the oil film model; selecting steady-state solution in fluid simulation software, and sequentially setting material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface and solution method; performing initialization and the first calculation in fluid simulation software in sequence to obtain the oil film pressure distribution when the journal is at the initial position; setting output parameters; generating a series of design points in the experimental design module of response surface optimization, and conducting corresponding experiments to obtain experimental results; generating a response surface based on the experimental results, and performing optimization according to the generated response surface to obtain the balance position of the journal. The operation of the present invention is simple, does not involve complex mathematical derivations and programming, and hardly introduces simplified assumptions. It can comprehensively consider the influence of factors such as viscous heating, viscosity-temperature effect, multiphase flow, etc., is more consistent with the actual situation, and has high calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 is the flowchart of the method provided by the embodiment of the present invention;

[0036] Figure 2 is the schematic diagram of the solution process provided by the embodiment of the present invention;

[0037] Figure 3 is the schematic diagram of the oil film model provided by the embodiment of the present invention;

[0038] Figure 4 is the schematic diagram of the mesh division of the oil film model provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0040] The purpose of the present invention is to provide a method for solving the equilibrium position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump, which is simple to operate, does not involve complex mathematical derivations and programming, and hardly introduces simplified assumptions. It can comprehensively consider the influences of factors such as viscous heating, viscosity-temperature effect, and multiphase flow, is more in line with the actual situation, and has high calculation accuracy.

[0041] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Figure 1 The flow chart of the method provided by the embodiment of the present invention is as Figure 1 shown. The present invention provides a method for solving the equilibrium position of the journal of a radial sliding bearing of a dense-phase CO2 transfer pump, including:

[0043] Step 100: Construct an oil film model of the radial sliding bearing to be studied, and determine the input parameters according to the oil film model; the input parameters include the horizontal offset and vertical offset of the journal.

[0044] Step 200: Select and define the inlet, wall surface, and outlet of the oil film model to perform mesh division on the oil film model.

[0045] Step 300: Select steady-state solution in the fluid simulation software, and sequentially set material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface, and solution method.

[0046] Step 400: Perform initialization and the first calculation in the fluid simulation software to obtain the oil film pressure distribution when the journal is at the initial position.

[0047] Step 500: Set the output parameters; generate a series of design points in the experimental design module of response surface optimization, and conduct corresponding experiments to obtain experimental results.

[0048] Step 600: Generate a response surface based on the experimental results, and optimize according to the generated response surface to obtain the equilibrium position of the journal.

[0049] Specifically, the process of this embodiment is as Figure 2 shown, and specifically includes the following steps:

[0050] Step 1: Use the DesignModeler module of the Workbench platform to construct an oil film model of the radial sliding bearing to be studied. Preferably, as Figure 3As shown, the oil film model includes a thin film part (1) between the journal and the bearing bush and a cylindrical part (2) of the oil inlet. The journal diameter is 79.8 mm, the length is 100 mm, the bearing bush diameter is 80 mm, the length is 100 mm, the oil inlet diameter is 4 mm, and the height is 5 mm;

[0051] Step 2: Set the horizontal offset and vertical offset of the journal in Step 1 as input parameters, namely P1 and P2 respectively, and set the initial values to prepare for response surface optimization. Preferably, the initial value of the horizontal offset of the journal is set to 0.03 mm, and the initial value of the vertical offset is set to 0.04 mm;

[0052] Step 3: Select and define the inlet, wall, and outlet of the oil film model in the Mesh module, and perform mesh division on the oil film model. Preferably, as Figure 4 shown, divide the thin film into 720 equal parts circumferentially, 250 equal parts axially, and 3 equal parts in thickness. Divide the oil inlet into 40 equal parts circumferentially and 20 equal parts in height;

[0053] Step 4: Select steady-state solution in Fluent;

[0054] Step 5: Set the material properties in Fluent. Preferably, set the liquid-phase material according to the N32 lubricating oil used, set the viscosity through UDF to introduce the viscosity-temperature effect, and set the gas-phase material for the lubricating oil vapor;

[0055] Step 6: Set the multiphase flow in Fluent. Preferably, select the Mixture model, select the liquid-phase material for the first phase, select the gas-phase material for the second phase, select the Schnerr-Sauer model in cavitation for mass transfer, and set the vaporization pressure to 30000 Pa;

[0056] Step 7: Set the viscous model in Fluent. Preferably, select the Laminar model and check ViscousHeating;

[0057] Step 8: Set the operating pressure in Fluent. Preferably, set the operating pressure to 0 Pa;

[0058] Step 9: Set the boundary conditions in Fluent. Preferably, set the inlet gauge pressure to 120000 Pa, the temperature to 298.15 K, set the outlet gauge pressure to 101325 Pa, the total temperature of the return flow to 298.15 K, set the journal wall to a moving wall, the rotational speed to 3000 rpm, the heat flux to 0, and set the other walls to stationary walls, the heat flux to 0;

[0059] Step Ten: Set the grid interface in Fluent. Preferably, set the wall surface of the bearing shell and the bottom surface of the oil inlet as the interface;

[0060] Step Eleven: Set the solution method in Fluent. Preferably, select the Coupled format for the pressure-velocity coupling algorithm. For spatial discretization, select the PRESTO! format for the pressure, and select the first-order upwind for other flux formats. Set the number of iterations to 500 times. When the mass flow rate difference between the inlet and the outlet is less than 1%, it is considered that the iteration converges;

[0061] Step Twelve: Initialize in Fluent. Preferably, select hybrid initialization;

[0062] Step Thirteen: Conduct the first calculation in Fluent to obtain the oil film pressure distribution when the journal is at the initial position;

[0063] Step Fourteen: Set the output parameters in CFD Post. Preferably, set the horizontal oil film force acting on the journal as Fx = force_x()@moving_wall, the vertical oil film force as Fy = force_y()@moving_wall, and their ratio as Ratio of Fx to Fy = Fx / Fy. Set the three variables as output parameters, namely P3, P4, and P5;

[0064] Step Fifteen: Generate a series of design points in the experimental design module of response surface optimization and conduct corresponding experiments. Preferably, select the Central Composite Design and Rotatable for the experimental design type, and set the value ranges of P1 and P2 to 0 - 0.05 mm;

[0065] Step Sixteen: Generate a response surface based on the experimental results;

[0066] Step Seventeen: Optimize based on the generated response surface to obtain the equilibrium position of the journal. Preferably, set the optimization objectives as P4 = 4000 N, P5 = 0, with a tolerance of 0.001 for both. Check "Verify candidate points", calculate to obtain 3 candidate design points, and select the 1 candidate design point that is closest to the optimization objective, namely P1 = 0.036977 mm, P2 = 0.029228 mm, and verify to obtain the corresponding P4 = 4010.7 N, P5 = -0.0026.

[0067] In the DesignModeler module of the present invention, the horizontal offset and vertical offset of the journal of the radial sliding bearing are set as input parameters to achieve parameterization; in CFD Post, the horizontal oil film force, vertical oil film force and the ratio between the two acting on the journal are set as output parameters to achieve parameterization; and response surface optimization is used to optimize the horizontal offset and vertical offset of the journal with "the vertical oil film force acting on the journal is equal to the load, and the ratio of the horizontal oil film force to the vertical oil film force is equal to 0" as the optimization goal, thereby achieving accurate and rapid calculation of the journal equilibrium position of the radial sliding bearing of the dense phase CO2 transfer pump under a given speed and load.

[0068] The beneficial effects of the present invention are as follows:

[0069] (1) The technical solution proposed in the present invention is simple to operate, does not involve complex mathematical derivation and programming, and almost does not introduce simplified assumptions. It can comprehensively consider the influence of factors such as viscous heating, viscosity-temperature effect, and multiphase flow, which is more consistent with the actual situation and has high calculation accuracy.

[0070] (2) The technical solution proposed in the present invention can avoid the huge amount of calculation brought by the point-by-point scanning method with the help of the response surface optimization algorithm, thereby significantly improving the solution efficiency while ensuring the calculation accuracy.

[0071] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0072] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for solving the equilibrium position of the journal of the radial sliding bearing of a dense phase CO2 delivery pump, characterized in that: include: Constructing an oil film model of the radial sliding bearing to be studied, and determining input parameters according to the oil film model; The input parameters include the horizontal offset and vertical offset of the journal; Selecting and defining an inlet, a wall, and an outlet of the oil film model to perform mesh division on the oil film model; Select steady-state solution in the fluid simulation software and set the material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface and solution method in sequence; Initialization and the first calculation are performed in sequence in the fluid simulation software to obtain the oil film pressure distribution when the journal is in the initial position; Set output parameters; Generate a series of design points in the experimental design module of response surface optimization, conduct corresponding experiments, and obtain experimental results; generating a response surface based on the experimental results, and performing optimization according to the generated response surface to obtain an equilibrium position of the journal; The oil film model includes the thin film portion between the journal and the bearing shell and the cylindrical portion of the oil inlet; the journal has a diameter of 79.8 mm and a length of 100 mm; the bearing shell has a diameter of 80 mm and a length of 100 mm; the oil inlet has a diameter of 4 mm and a height of 5 mm; Select the steady-state solution in the fluid simulation software and set the material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface, and solution method in sequence, including: Set the liquid phase material according to the N32 lubricant used, set the viscosity through UDF, introduce the viscosity-temperature effect, and set the gas phase material for the lubricant vapor; Select Mixture model, select liquid phase material for the first phase, select gas phase material for the second phase, select Schnerr-Sauer model in cavitation for mass transfer, and set the vaporization pressure to 30000Pa; Select the Laminar model and check Viscous Heating; Set the operating pressure to 0Pa; Set the inlet gauge pressure to 120000Pa, the temperature to 298.15K, the outlet gauge pressure to 101325Pa, the reflux total temperature to 298.15K, the journal wall to the moving wall, the speed to 3000rpm, the heat flux to 0, and the other walls to the stationary wall, with a heat flux of 0; The bearing wall surface and the bottom surface of the oil inlet are set as the interface; The pressure-velocity coupling algorithm is selected as Coupled format. In the spatial discretization, the pressure format is selected as PRESTO, and the other flux formats are all selected as first-order upwind. The number of iterations is set to 500. When the difference in mass flow rate between the inlet and outlet is less than 1%, the iteration is determined to have converged. A response surface is generated based on the experimental results, and optimization is performed based on the generated response surface to obtain the equilibrium position of the journal, including: Set the optimization target, the vertical oil film force is 4000N, the ratio of the horizontal oil film force to the vertical oil film force is 0, and the tolerance is 0.001; Check "Verify candidate points" to calculate 3 candidate design points; A candidate design point closest to the optimization target is selected, that is, the horizontal offset is 0.036977 mm and the vertical offset is 0.029228 mm. It is verified that the corresponding vertical oil film force is 4010.7 N, and the ratio of the horizontal oil film force to the vertical oil film force is -0.0026.

2. The method for determining the journal equilibrium position of a radial sliding bearing of a dense phase CO2 delivery pump according to claim 1, characterized in that: The initial value of the horizontal offset is set to 0.03 mm, and the initial value of the vertical offset is set to 0.04 mm.

3. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 1 is characterized in that: Meshing the oil film model includes: The film portion is divided into 720 equal parts in the circumferential direction, 250 equal parts in the axial direction, and 3 equal parts in thickness. The oil inlet is divided into 40 equal parts in the circumferential direction and 20 equal parts in height.

4. The method for determining the journal equilibrium position of a radial sliding bearing of a dense phase CO2 delivery pump according to claim 1, characterized in that: The initialization is mixed initialization.

5. The method for determining the journal equilibrium position of a radial sliding bearing of a dense phase CO2 delivery pump according to claim 1, characterized in that: The output parameters include: horizontal oil film force, vertical oil film force and the ratio of the horizontal oil film force to the vertical oil film force on the journal.

Images