A method of designing a vacuum condenser

Abstract

The application discloses a design method of a vacuum condenser and relates to the field of heat exchange equipment, and comprises the following steps: S1, initially determining structure parameters of the vacuum condenser according to design parameters; S2, completing a preliminary heat exchange tube layout according to the structure parameters; S3, through the mode of an equivalent heat exchanger, performing process and hydraulics calculation by using computer software to determine a heat transfer coefficient, a heat exchange area, a tube bundle pressure drop, an inlet connecting pipe pressure drop and a non-condensable gas outlet connecting pipe pressure drop; S4, calculating a variable direction pressure drop at a medium turning position; S5, calculating an overall pressure drop of the vacuum condenser, and if the requirement is met, determining a selection scheme; if the requirement cannot be met, returning to S1 to redesign; and S6, determining a final scheme; in the application, data accuracy is high, and the optimization effect of structure parameters is good; not only can the structure of the vacuum condenser be improved, the volume of the vacuum condenser be reduced and the calculation accuracy of the vacuum condenser be improved, but also the overall optimization of a vacuumizing system is facilitated, equipment investment is reduced and operation energy consumption is lowered.

Description

Technical Field

[0001] This invention relates to the field of heat exchange equipment, and in particular to a design method for a vacuum condenser. Background Technology

[0002] Vacuum condensers are one of the key pieces of equipment in a vacuum system. They cool and partially condense the oil and gas pumped out by the pump, and then discharge the condensate to reduce the system temperature. The performance (including heat transfer efficiency and pressure drop) and stability of the condenser are directly related to the reliability of the vacuum system.

[0003] Because the oil and gas extracted by the vacuum pump have characteristics such as low operating pressure and small heat transfer coefficient, the cooler usually needs to optimize its internal structure by setting up special flow channels and increasing the number of tubes. This means that the vacuum condenser cannot be calculated for heat transfer and hydraulics simply by using mainstream professional calculation software (such as HTRI, EDR, etc.). Designers still need to perform manual calculations based on theory and experience, resulting in low data accuracy and poor optimization of structural parameters.

[0004] Therefore, there is an urgent need for a design method for vacuum condensers with good structural parameter optimization. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for a vacuum condenser to solve the problems existing in the prior art, and to improve the optimization effect of structural parameters through equivalent heat exchanger calculation.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides a design method for a vacuum condenser, comprising the following steps:

[0007] S1: Preliminarily determine the structural parameters of the vacuum condenser based on the design parameters of the vacuum condenser;

[0008] S2: Based on the determined structural parameters of the vacuum condenser, complete the preliminary heat exchange tube layout diagram, and determine the position and size of the baffle, the position of the connecting pipe, and the anti-impact height;

[0009] S3: By using an equivalent heat exchanger, computer software is used to perform process and hydraulic calculations to determine the heat transfer coefficient, heat exchange area, tube bundle pressure drop, inlet pipe pressure drop, and non-condensable gas outlet pipe pressure drop.

[0010] S4: Calculate the pressure drop at the turning point of the medium based on the baffle size;

[0011] S5: Calculate the overall pressure drop of the vacuum condenser. If it meets the requirements, determine the selection scheme; if it does not meet the requirements, return to S1 to adjust the scheme and recalculate.

[0012] S6: Determine the final solution and complete the preparation of process documents.

[0013] Preferably, in step S1, the design parameters of the vacuum condenser include the medium operating temperature, operating pressure, physical property data, design temperature, design pressure, and equipment material.

[0014] Preferably, in step S1, the structural parameters of the vacuum condenser are determined by computer software. The structural parameters of the vacuum condenser include the equipment diameter, the number of tubes, the number of heat exchange tubes, the length of the heat exchange tubes, the size of the connecting pipes, and the number of connecting pipes.

[0015] Preferably, in step S2, the baffle divides the fluid flow path inside the vacuum condenser shell into three parts: a two-phase co-current region, a gas-phase turning region, and a gas-liquid split region. In step S3, all heat exchange tubes are divided into several units according to the number of heat exchange tube rows along the fluid flow direction inside the shell. The size of the equivalent heat exchanger is determined according to the number of heat exchange tube rows and the number of heat exchange tubes per row in each of the three regions. The number of heat exchange tube rows and the number of heat exchange tubes per row in the equivalent heat exchanger are the same as those in the corresponding regions. Using computer software, the three equivalent heat exchangers are simulated and calculated in a series configuration to obtain the heat transfer coefficient and pressure drop of each of the three parts, thereby obtaining the overall heat transfer coefficient, pressure drop, and area margin of the heat exchange tubes.

[0016] Preferably, the pressure drop of each region or the equivalent heat exchanger corresponding to the region is the sum of the pressure drops of all units within the region or the equivalent heat exchanger, and the heat transfer coefficient is the average value of the heat transfer coefficients of all units within the region or the equivalent heat exchanger calculated according to the load ratio.

[0017] Preferably, after step S3, the pressure drop and heat exchange area are determined based on the calculation results to see if they meet the margin requirements. If they do, proceed to step S4; otherwise, return to step S1, adjust the structural parameters, and recalculate.

[0018] Preferably, in step S5, the overall pressure drop of the vacuum condenser includes the tube bundle pressure drop, the inlet pipe pressure drop, the non-condensable gas outlet pipe pressure drop, and the directional pressure drop.

[0019] Preferably, after step S5, based on the determined selection scheme, the heat exchange tubes are locally optimized by adding bypass baffles and increasing the number of non-pipe areas.

[0020] Preferably, in step S2, the arrangement of the heat exchange tubes is fully considered to ensure that the tube-side medium and the flowing medium inside the shell flow in a completely countercurrent manner.

[0021] Preferably, in step S2, the direction of the medium flow in the tube is perpendicular to the direction of the medium flow in the shell.

[0022] The present invention achieves the following main technical effects compared to the prior art:

[0023] After initially determining the structural parameters of the vacuum condenser, the heat exchanger tube layout diagram is completed using these parameters. Based on this, relevant data is calculated using the equivalent heat exchanger calculation method. The feasibility of the current scheme is judged by the calculation results, and then the scheme is determined. This eliminates the need for manual calculations, improves data accuracy, and enhances the optimization effect of structural parameters. This not only improves the vacuum condenser structure, reduces the vacuum condenser volume, and improves the accuracy of vacuum condenser calculations, but also facilitates the overall optimization of the vacuum pumping system, reduces equipment investment, and lowers operating energy consumption, resulting in significant social and economic benefits. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of the vacuum condenser design method in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the external structure of the vacuum condenser in an embodiment of the present invention;

[0027] Figure 3 This is a diagram showing the tube bundle arrangement of the housing in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram illustrating the flow characteristics and path of the fluid to be cooled in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the equivalent heat exchanger in the two-phase co-current region in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the equivalent heat exchanger in the gas phase turning zone in an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the equivalent heat exchanger in the gas-liquid splitting zone in an embodiment of the present invention;

[0032] The components are as follows: 1. Shell; 2. Inlet pipe; 3. Non-condensable gas outlet pipe; 4. Condensate outlet pipe; 5. Refrigerant inlet pipe; 6. Refrigerant outlet pipe; 7. Drain pipe; 8. Process gas side exhaust pipe; 9. Fixed saddle; 10. Sliding saddle; 11. Tube bundle; 12. Heat exchange tube; 13. Baffle; 14. Bypass baffle; 15. No pipe section; 16. Two-phase co-current flow section; 17. Gas phase reversal section; 18. Gas-liquid separation section. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a design method for a vacuum condenser to solve the problems existing in the prior art and improve the optimization effect of structural parameters through equivalent heat exchanger calculation.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Please refer to the following: Figures 1-7 As shown, a design method for a vacuum condenser is provided, including the following steps:

[0037] S1: Based on the design parameters of the vacuum condenser (including medium operating temperature, operating pressure, physical property data, design temperature, design pressure, equipment material, etc.), the structural parameters of the vacuum condenser are initially determined;

[0038] S2: Based on the determined structural parameters of the vacuum condenser, complete the preliminary layout of the heat exchange tube 12, determine the position and size of the baffle 13, the position of the connecting pipes (inlet connecting pipe 2, non-condensable gas outlet connecting pipe 3, condensate outlet connecting pipe 4, etc.) and the anti-impact height (the distance between the inlet connecting pipe 2 and the heat exchange tube 12 that is directly impacted by the fluid).

[0039] S3: By using an equivalent heat exchanger, computer software is used to perform process and hydraulic calculations to determine the heat transfer coefficient, heat exchange area, tube bundle pressure drop, inlet pipe 2 pressure drop and non-condensable gas outlet pipe 3 pressure drop.

[0040] S4: Calculate the pressure drop at the medium turning point based on the dimensions of baffle 13;

[0041] S5: Calculate the overall pressure drop of the vacuum condenser (including the pressure drop of tube bundle 11, inlet pipe 2, non-condensable gas outlet pipe 3, and the directional pressure drop). If the requirements are met, determine the selection scheme; if the requirements are not met, return to S1 to adjust the scheme and recalculate.

[0042] S6: Determine the final solution and complete the preparation of process documents.

[0043] The structural parameters of a vacuum condenser are determined by computer software (such as HTRI, EDR, etc.) or by combining the designer's experience with the computer software. The structural parameters of a vacuum condenser include the equipment diameter, the number of tubes, the number of heat exchange tubes, the length of the heat exchange tubes, the size of the connecting pipes, and the number of connecting pipes.

[0044] In step S2, the baffle 13 is a structure that extends the fluid flow path inside the vacuum condenser shell 1. It is located between the inlet pipe 2 and the non-condensable gas outlet pipe 3, making the fluid flow path V-shaped. The baffle 13 divides the fluid flow path inside the vacuum condenser shell 1 into three parts: a two-phase co-current flow zone 16, a gas phase turning zone 17, and a gas-liquid split zone 18.

[0045] The principle of "equivalence" in this embodiment is as follows:

[0046] Since the heat transfer coefficient can be considered as a function of the medium flow rate, temperature difference, and physical properties, and the pressure drop can be considered as a function of the medium flow rate, flow rate, and physical properties, the heat transfer coefficient and pressure drop of the i-th row of heat exchange tubes 12 (i.e., the i-th unit) can be expressed as follows:

[0047] ;

[0048] ;

[0049] Where K is the heat transfer coefficient; M is the number of heat exchange tubes 12, and their spacing (i.e., flow area) determines the medium flow rate; ΔT is the heat transfer temperature difference; P1, P2, etc. are all medium properties; ΔP is the pressure drop; and N is the number of tube rows, used to characterize the medium flow rate.

[0050] Therefore, the heat transfer coefficient of each region or the equivalent heat exchanger corresponding to the region is the average value of the heat transfer coefficients of all units within that region or the equivalent heat exchanger, calculated according to the load ratio, and the pressure drop is the sum of the pressure drops of all units within that region or the equivalent heat exchanger.

[0051] The specific formulas for calculating pressure drop and heat transfer coefficient are as follows:

[0052]

[0053] ;

[0054] Where Q is the heat load. The average heat transfer temperature difference.

[0055] Therefore, based on the partitioning effect of the baffle 13, in step S3, the tube bundle 11 is divided into several units according to the number of rows of heat exchange tubes 12 along the fluid flow direction inside the shell 1. The size of the equivalent heat exchanger is determined according to the number of rows of heat exchange tubes 12 in each of the three regions and the number of heat exchange tubes 12 in each row. The number of rows of heat exchange tubes 12 in the equivalent heat exchanger and the number of heat exchange tubes 12 in each row are the same as the corresponding regions. Using computer software, the three equivalent heat exchangers are simulated and calculated in a series configuration to obtain the heat transfer coefficient and pressure drop of each of the three parts, thereby obtaining the overall heat transfer coefficient, pressure drop and area margin of the heat exchange tubes 12.

[0056] After step S3, the pressure drop and heat exchange area are determined based on the calculation results to see if they meet the margin requirements. If they do, proceed to step S4; otherwise, return to step S1, adjust the structural parameters, and recalculate.

[0057] The formula for calculating the change-of-direction pressure drop at the medium turning point is:

[0058]

[0059] Among them, F i : Fluid mass flow rate, kg / m2s;

[0060] ρ iD Fluid density, kg / m³ 3 ;

[0061] N: A correction factor representing the turning angle. For an approximate 90-degree turn, the correction factor is set to 1.

[0062] After step S5, based on the determined selection scheme, the heat exchange tube 12 is locally optimized by adding a bypass baffle 14 and adding a non-pipe zone 15. The bypass baffle 14 is to prevent fluid bypass, and the non-pipe zone 15 is to form a uniform gas channel, improve the uniformity of fluid flow in this area, and prevent dead zones with poor fluid flow from appearing inside the gas-liquid split zone 18.

[0063] In step S2, the arrangement of the heat exchange tubes 12 is fully considered to ensure that the tube-side medium and the flowing medium inside the shell 1 flow in a completely countercurrent manner, thereby improving the heat transfer effect.

[0064] Considering that the medium flow rate is very high under high vacuum conditions and the equipment is prone to vibration, in step S2, the medium flow direction in the tube is perpendicular to the flow direction of the medium inside the shell 1 to ensure that the equipment will not be damaged by vibration.

[0065] The vacuum condenser designed in this embodiment is a floating head vacuum condenser, and the heat exchange tube 12 can be pulled out for easy maintenance and cleaning in the future.

[0066] In this embodiment, the number of tubes is 6-8, so that the circulating water can reach the highest possible flow rate while meeting the pressure drop requirements, thereby improving heat exchange efficiency and slowing down fouling.

[0067] In this embodiment, the fluid in the gas-liquid separation zone 18 flows obliquely upward, and the gas and liquid phases separate under the action of gravity. The equivalent calculation process uses a "reflux condenser" model, which helps to more accurately simulate the pressure drop and heat transfer performance.

[0068] The vacuum condenser designed in this embodiment includes a shell 1, an inlet pipe 2, a non-condensable gas outlet pipe 3, a condensate outlet pipe 4, a refrigerant inlet pipe 5, a refrigerant outlet pipe 6, a drain pipe 7, a process gas side exhaust pipe 8, a fixed saddle 9, a sliding saddle 10, a tube bundle 11, a baffle 13, a bypass baffle 14, a non-pipeline zone 15, a two-phase co-current zone 16, a gas phase reversal zone 17, and a gas-liquid split zone 18. All pipes are installed on the shell 1. The inlet pipe 2 is used to supply the fluid to be cooled, the non-condensable gas outlet pipe 3 is used to discharge the gas phase fluid, the condensate outlet pipe 4 is used to discharge the cooled condensate, and the refrigerant inlet / outlet pipes are used to supply / discharge the refrigerant. Drain pipes are located on both sides. Pipe 7 is used to discharge wastewater from the two cavities on both sides of the shell 1 (the two cavities are the tube box cavity connected to the refrigerant inlet pipe 5 and the refrigerant outlet pipe 6, respectively, and the spherical cavity connected to the inner cavity of the shell 1 on the other side). The process gas side exhaust pipe 8 is used to discharge gas from the shell 1. The fixed saddle 9 and the sliding saddle 10 are used for support. The tube bundle 11 is arranged inside the shell 1 and is parallel to the axis of the shell 1. The tube bundle 11 is composed of multiple heat exchange tubes 12. The baffle 13 is fixedly installed inside the shell 1 to divide the inner cavity of the shell 1 into a V-shaped channel. The bypass baffle 14 blocks the gap between the tube bundle 11 and the inner wall of the shell 1 to prevent the fluid to be cooled from flowing by. The non-pipe area 15 is used to improve the flow uniformity.

[0069] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0070] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0071] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A design method for a vacuum condenser, characterized in that, Includes the following steps: S1: Preliminarily determine the structural parameters of the vacuum condenser based on the design parameters of the vacuum condenser; S2: Based on the determined structural parameters of the vacuum condenser, complete the preliminary heat exchange tube layout diagram, determine the position and size of the baffle, the position of the connecting pipe and the anti-impact height. The baffle divides the fluid flow path inside the vacuum condenser shell into three parts: the two-phase co-current zone, the gas phase turning zone and the gas-liquid separation zone. S3: Using an equivalent heat exchanger, computer software is used to perform process and hydraulic calculations to determine the heat transfer coefficient, heat exchange area, tube bundle pressure drop, inlet pipe pressure drop, and non-condensable gas outlet pipe pressure drop. All heat exchange tubes are divided into several units according to the number of heat exchange tube rows along the fluid flow direction inside the shell. The size of the equivalent heat exchanger is determined based on the number of heat exchange tube rows and the number of heat exchange tubes per row in each of the three regions. The number of heat exchange tube rows and the number of heat exchange tubes per row in the equivalent heat exchanger are the same as those in the corresponding regions. Using computer software, the three equivalent heat exchangers are simulated and calculated in series to obtain the heat transfer coefficient and pressure drop of each of the three parts, and then the overall heat transfer coefficient, pressure drop, and area margin of the heat exchange tubes are obtained. S4: Calculate the pressure drop at the turning point of the medium based on the baffle size; S5: Calculate the overall pressure drop of the vacuum condenser. If it meets the requirements, determine the selection scheme; if it does not meet the requirements, return to S1 to adjust the scheme and recalculate. S6: Determine the final solution and complete the preparation of process documents.

2. The design method for a vacuum condenser according to claim 1, characterized in that, In step S1, the design parameters of the vacuum condenser include the medium operating temperature, operating pressure, physical property data, design temperature, design pressure, and equipment material.

3. The design method for a vacuum condenser according to claim 2, characterized in that, In step S1, the structural parameters of the vacuum condenser are determined by computer software. The structural parameters of the vacuum condenser include the equipment diameter, the number of tubes, the number of heat exchange tubes, the length of the heat exchange tubes, the size of the connecting pipes, and the number of connecting pipes.

4. The design method of the vacuum condenser according to claim 1, characterized in that, The pressure drop of each region or the equivalent heat exchanger corresponding to that region is the sum of the pressure drops of all units within that region or the equivalent heat exchanger, and the heat transfer coefficient is the average value of the heat transfer coefficients of all units within that region or the equivalent heat exchanger calculated according to the load ratio.

5. The design method for a vacuum condenser according to claim 1, characterized in that, After step S3, the pressure drop and heat exchange area are determined based on the calculation results to see if they meet the margin requirements. If they do, proceed to step S4; otherwise, return to step S1, adjust the structural parameters, and recalculate.

6. The design method of the vacuum condenser according to claim 1, characterized in that, In step S5, the overall pressure drop of the vacuum condenser includes the tube bundle pressure drop, the inlet pipe pressure drop, the non-condensable gas outlet pipe pressure drop, and the directional pressure drop.

7. The design method for a vacuum condenser according to claim 1, characterized in that, After step S5, based on the determined selection scheme, the heat exchange tubes are locally optimized, including adding bypass baffles and increasing the number of non-pipe areas.

8. The design method of the vacuum condenser according to claim 1, characterized in that, In step S2, the arrangement of the heat exchange tubes is fully considered to ensure that the tube-side medium and the flowing medium inside the shell flow in a completely countercurrent manner.

9. The design method for a vacuum condenser according to claim 1, characterized in that, In step S2, the direction of the medium flow in the tube is perpendicular to the direction of the medium flow in the shell.

Images