Model selection method of electric diverter valve suitable for fused salt heating steam generator

Abstract

A model selection method suitable for an electric diverter valve of a fused salt heating steam generator belongs to the technical field of instrument automation, and comprises the following steps: determining functions realized by an electric three-way regulating valve, and selecting inherent flow characteristics of the valve according to the functions; the method comprises the following steps: preliminarily selecting a valve caliber and a valve seat diameter according to a process pipeline connected with a valve, and inquiring related product samples to obtain a valve flow coefficient C100, an ideal adjustable ratio R and a pipeline valve resistance ratio S under the specification; obtaining a flow coefficient C of the maximum flow of the main passage; the opening degree K is calculated, and whether the opening degree K ranges from 50% to 80% or not is judged; and calculating a volatility B, and selecting the valve caliber with the minimum volatility B as a model selection result. According to the method, it is guaranteed that the valve type selection parameters are matched with the operation working condition of the hot molten salt steam generation system, so that distribution of heat loads is effectively controlled, high-temperature molten salt adjusting valve type selection calculation is optimized, and an effective technical guarantee is provided for development of molten salt heat storage application in the aspect of oil field steam injection in the future.

Description

Technical Field

[0001] The invention belongs to the technical field of instrument automation, and in particular relates to a method for selecting an electric diverter valve suitable for a molten salt heating steam generator. Background Art

[0002] The Liaohe Oilfield production system consumed 1.64 billion cubic meters of natural gas and 2.24 billion kWh of electricity, equivalent to 2.4565 million tons of standard coal, CO 2 The emission volume was 5.28594 million tons. Natural gas consumption accounted for 88.8% of the total energy consumption, which was mainly used for steam injection in heavy oil thermal recovery and was a key link in energy consumption. Explore the use of electric molten salt heat storage technology to replace gas consumption and realize "replacing gas with valley electricity / green electricity". After the implementation of this technology, it can not only reduce carbon dioxide emissions, but also make full use of valley electricity / green electricity and reduce the pressure on the power grid. Liaohe Oilfield is the largest heavy oil production base in the country. The steam injection system required in the heavy oil extraction process requires wet saturated steam with a certain dryness. The steam generation system with molten salt as the heat transfer medium, equipped with appropriate control methods, can effectively produce saturated steam with qualified dryness to meet the production needs of the oilfield.

[0003] As the key core equipment for process control in steam generators, the selection parameters of electric three-way diverter control valves, including valve seat diameter, flow characteristics, etc., directly determine the regulation efficiency and accuracy of the steam generation system. The application of three-way regulating valves in this system can effectively reduce costs and installation space. In the steam generation system, the three-way regulating valve mainly regulates the proportion of hot molten salt flowing into the steam generator, and does not produce a throttling effect on the total flow. The current common method is that designers provide valve manufacturers with the valve operating condition flow and pressure difference range. The manufacturer selects the valve caliber according to the above parameters and the adjustable opening range of the valve and the ideal flow characteristic formula. The disadvantage of this method is that it is difficult for manufacturers to select valves based on the overall pipeline flow characteristics of the regulating valve and the heat exchanger. The selection calculation is based on the ideal flow characteristic formula of the valve, which easily causes the valve caliber to deviate from the actual operating conditions, resulting in insufficient regulation capacity. Therefore, this patent provides a selection method for three-way regulating valves suitable for hot molten salt steam generation systems. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes: a method for selecting an electric diverter valve suitable for a molten salt heating steam generator, comprising the following steps:

[0005] S1. Determine the function of the electric three-way regulating valve and select the inherent flow characteristics of the valve according to the function;

[0006] S2. Preliminarily select the valve caliber and valve seat diameter according to the process pipeline connected to the valve, and consult relevant product samples to obtain the valve flow coefficient C under this specification. 100, ideal adjustable ratio R, pipeline valve resistance ratio S;

[0007] S3, obtain the maximum flow of the diverter valve main line, close one diverter channel (the branch not connected to the heat exchange equipment) and calculate the incompressible fluid flow coefficient C according to the calculation formula (1);

[0008]

[0009] Q is the flow rate m 3 / h,G f Liquid medium and water (1000kg / m 3 ) density ratio, ΔP is the valve differential pressure MPa (A), N is a constant, the unit is taken according to the physical quantity. In this formula, N = 0.3655

[0010] S4, according to the selected valve inherent flow characteristics and C 100 , determine the valve opening under the current working conditions, use formula (2) for linear characteristic valves and formula (3) for equal percentage characteristic valves, and verify that the opening K is between 50% and 80% when the maximum flow C is reached. Loop through steps 3 and 4, add the valve seat diameters that meet the opening requirements to queue A, then reduce the valve seat diameter by one level, reselect parameters and continue the next cycle until all valve seat diameters that meet the requirements are exhausted.

[0011]

[0012]

[0013] S5. Check the fluctuation rate of valves of different diameters in queue A one by one through the change of system resistance. The valve with small fluctuation rate is excellent. The specific method is as follows:

[0014] Define the Cv value of the three-way regulating valve as C 100 The system flow coefficients when the three-way regulating valve a is fully open, intermediate open, and b is fully open are C a , C 中 , C b Here, path a is defined as the path connected to the heat exchange equipment, and the pressure difference of the heat exchanger is Δp h , define the flow coefficient of each branch when the three-way regulating valve is 50% as C 50 , for linear characteristic valve C 50 From formula (4), it can be concluded that for equal percentage characteristic valve C 50 From formula (5), we can get C according to formula (1): h According to formulas (6) to (8), C a , C 中 , C b ;

[0015]

[0016]

[0017]

[0018]

[0019] C b =C 100 Formula (8)

[0020] Define the volatility as B, and get it from formula (9):

[0021]

[0022] Read the flow coefficients of all valves in queue A in turn and bring them into the calculation. The valve caliber with the smallest fluctuation rate B is the selection result.

[0023] The beneficial effects of the present invention are as follows: the present invention ensures that the valve selection parameters match the operating conditions of the hot molten salt steam generation system, thereby effectively controlling the distribution of the heat load. The present invention optimizes the selection calculation of the high-temperature molten salt regulating valve and provides effective technical guarantee for the future development of molten salt heat storage applications in oil field steam injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart for selecting the electric diverter valve of the present invention;

[0025] Figure 2 It is a flow chart of the equipment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical means and objectives of the present invention easy to understand, the present invention is further described below in combination with specific embodiments. A method for selecting an electric diverter valve suitable for a molten salt heating steam generator is as follows: Figure 1 As shown, the following steps are included:

[0027] S1. Determine the function of the electric three-way regulating valve and select the inherent flow characteristics of the valve according to the function;

[0028] S2. Preliminarily select the valve caliber and valve seat diameter according to the process pipeline connected to the valve, and consult relevant product samples to obtain the valve flow coefficient C under this specification. 100 , ideal adjustable ratio R, pipeline valve resistance ratio S;

[0029] S3, obtain the maximum flow of the diverter valve main line, close one diverter channel (the branch not connected to the heat exchange equipment) and calculate the incompressible fluid flow coefficient C according to the calculation formula (1);

[0030]

[0031] Q is the flow rate m 3 / h,G f Liquid medium and water (1000kg / m 3 ) density ratio, ΔP is the valve differential pressure MPa (A), N is a constant, the unit is taken according to the physical quantity. In this formula, N = 0.3655

[0032] S4, according to the selected valve inherent flow characteristics and C 100 , determine the valve opening under the current working conditions, use formula (2) for linear characteristic valves and formula (3) for equal percentage characteristic valves, and verify that the opening K is between 50% and 80% when the maximum flow C is reached. Loop through steps 3 and 4, add the valve seat diameters that meet the opening requirements to queue A, then reduce the valve seat diameter by one level, reselect parameters and continue the next cycle until all valve seat diameters that meet the requirements are exhausted.

[0033]

[0034]

[0035] S5. Check the fluctuation rate of valves of different diameters in queue A one by one through the change of system resistance. The valve with small fluctuation rate is excellent. The specific method is as follows:

[0036] Define the Cv value of the three-way regulating valve as C 100 The system flow coefficients when the three-way regulating valve a is fully open, intermediate open, and b is fully open are C a , C 中 , C b Here, path a is defined as the path connected to the heat exchange equipment, and the pressure difference of the heat exchanger is Δp h , define the flow coefficient of each branch when the three-way regulating valve is 50% as C 50 , for linear characteristic valve C 50 From formula (4), it can be concluded that for equal percentage characteristic valve C 50 From formula (5), we can get C according to formula (1): h According to formulas (6) to (8), C a , C 中 , C b ;

[0037]

[0038]

[0039]

[0040]

[0041] C b =C 100 Formula (8)

[0042] Define the volatility as B, and get it from formula (9):

[0043]

[0044] Read the flow coefficients of all valves in queue A in turn and bring them into the calculation. The valve caliber with the smallest fluctuation rate B is the selection result.

[0045] Taking the steam generator hot molten salt heat exchange regulation as an example, the electric three-way regulating valve Fv is selected and calculated. The selection conditions are as follows:

[0046] The maximum total flow rate of the steam generation system is Q = 26m 3 / h, valve inlet pipeline specification D114.3×5, operating pressure 0.7MPa(A), valve pressure drop 0.08MPa, evaporator heat exchange pressure drop 0.1MPa, 560℃ hot molten salt operating density 1700kg / m 3 The equipment flow chart is as follows: Figure 2 shown.

[0047] This regulating valve is used for steam generator inlet flow regulation. The control flow range is large, and it is appropriate to use a valve with equal percentage flow characteristics.

[0048] According to the diameter of the process pipeline, the valve diameter is initially selected as DN100, and the sample is C 100 =185, R=50, S=0.5;

[0049] Substituting into formula (1), we get C = 43.8;

[0050] Substituting into formula (3) and calculating, the opening degree K = 59.59% is obtained, which meets the requirements, and the result is added to the queue.

[0051] Reduce the valve diameter and execute step S3 and step S4 cyclically. Finally, the condition result list is satisfied:

[0052] Valve diameter <![CDATA[C 100 ]]> Opening K DN100 185 59.59％ DN80 116 72.68％

[0053] Verify the fluctuation characteristics of the valves in the list one by one. For the DN100 three-way regulating valve, substitute it into formula (1) to obtain the evaporator equivalent flow coefficient C h =39.2, substituting into formula (5) to obtain C 50 =31.11, combined with formulas (5) to (9), the valve fluctuation rate list is as follows:

[0054] Valve diameter <![CDATA[C a ]]> <![CDATA[C 中 ]]> <![CDATA[C b ]]> Volatility B DN100 38.35 55.48 185 57.34％ DN80 37.14 36.98 116 34.28％

[0055] Therefore, it is advisable to use a DN80 three-way regulating valve, and the selection is completed.

[0056] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for selecting an electric diverter valve suitable for a molten salt heated steam generator. It is characterized in that The steps include: S1. Determine the function of the electric three-way regulating valve and select the inherent flow characteristics of the valve according to the function; S2. Preliminarily select the valve caliber and valve seat diameter according to the process pipeline connected to the valve, and consult relevant product samples to obtain the valve flow coefficient C under this specification. 100 , ideal adjustable ratio R, pipeline valve resistance ratio S; S3, obtain the maximum flow of the diverter valve main line, close one of the diverter channels, and calculate the incompressible fluid flow coefficient C according to calculation formula (1); Q is the flow rate m 3 / h,G f Liquid medium and water (1000kg / m 3 ) density ratio, ΔP is the valve differential pressure MPa (A), N is a constant, and the unit is taken according to the physical quantity. In this formula, N = 0.3655.

2. The method for selecting an electric diverter valve suitable for a molten salt heating steam generator according to claim 1, It is characterized in that In the step S1, a linear characteristic valve is selected according to the function.

3. The method for selecting an electric diverter valve suitable for a molten salt heating steam generator as claimed in claim 2, It is characterized in that The method further comprises step S41, wherein the valve has an inherent flow characteristic and a C 100 , determine the valve opening K under the current working conditions, and use formula (2) for the linear characteristic valve to verify that the opening K is between 50% and 80% when the maximum flow C is reached. Then, execute steps S3 and S41 in a loop, add the valve seat diameter corresponding to the opening that meets the requirements to queue A, and then reduce the valve seat diameter by one level, reselect the parameters and continue the next cycle until all valve seat diameters that meet the requirements are exhausted; 4. The method for selecting an electric diverter valve suitable for a molten salt heating steam generator as claimed in claim 3, It is characterized in that The method further includes step S51, performing fluctuation calculation on valves of different diameters in queue A one by one by changing the system resistance, and selecting valves with small fluctuation.

5. The method for selecting an electric diverter valve suitable for a molten salt heating steam generator as claimed in claim 4, It is characterized in that Define the Cv value of the three-way regulating valve as C 100 The system flow coefficients when the three-way regulating valve a is fully open, intermediate open, and b is fully open are C a , C 中 , C b , define path a as the path connecting the heat exchange equipment, and the pressure difference of the heat exchanger is Δp h , define the flow coefficient of each branch when the three-way regulating valve is 50% as C 50 , for linear characteristic valve C 50 From formula (4), we can get C according to formula (1): h According to formulas (6) to (8), C a , C 中 , C b ; C b =C 100 Formula (8) Define the volatility as B, and get it from formula (9): Read the flow coefficients of all valves in queue A in turn and bring them into the calculation. The valve caliber with the smallest fluctuation rate B is the selection result.

6. The method for selecting an electric diverter valve for a molten salt heated steam generator according to claim 1, It is characterized in that In the step S1, a valve with equal percentage characteristics is selected according to the function.

7. The method for selecting an electric diverter valve for a molten salt heated steam generator as claimed in claim 6, It is characterized in that The method further comprises step S42, wherein the valve has an inherent flow characteristic and a C 100 , determine the valve opening K under the current working conditions, and use formula (3) for equal percentage characteristic valves to verify that the opening K is between 50% and 80% when the maximum flow C is reached. Then, execute steps S3 and S42 in a loop, add the valve seat diameters that meet the opening requirements to queue A, and then reduce the valve seat diameter by one level. After reselecting the parameters, continue the next cycle until all valve seat diameters that meet the requirements are exhausted.

8. The method for selecting an electric diverter valve suitable for a molten salt heating steam generator according to claim 7, It is characterized in that The method further includes step S52, in which the fluctuation rate of valves with different diameters in queue A is verified one by one by the change of system resistance, and valves with small fluctuation rate are selected.

9. The method for selecting an electric diverter valve for a molten salt heated steam generator according to claim 8, It is characterized in that Define the Cv value of the three-way regulating valve as C 100 The system flow coefficients when the three-way regulating valve a is fully open, intermediate open, and b is fully open are C a , C 中 , C b , define path a as the path connecting the heat exchange equipment, and the pressure difference of the heat exchanger is Δp h , define the flow coefficient of each branch when the three-way regulating valve is 50% as C 50 , for equal percentage characteristic valve C 50 From formula (5), we can get C according to formula (1): h According to formulas (6) to (8), C a , C 中 , C b ; C b =C 100 Formula (8) Define the volatility as B, and get it from formula (9): Read the flow coefficients of all valves in queue A in turn and bring them into the calculation. The valve caliber with the smallest fluctuation rate B is the selection result.

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