Method for converting opening degree of valve by using resistor

Abstract

The invention belongs to the technical field of valve opening feedback, and particularly relates to a method for converting the valve opening through a resistor. Comprising the following steps: (1) circuit transformation: connecting the middle end of a slide rheostat R2 in an electric actuator of the valve to a PLC module, connecting the-V end of the slide rheostat R2 in series with a resistor R1 and then connecting the slide rheostat R2 to the PLC module; (2) converting the resistance value into a temperature value: obtaining a temperature maximum value Tmax, a temperature minimum value Tmin and a valve limit maximum opening Lmax by opening and closing the valve, and obtaining a real-time temperature value T; and (3) the temperature value is converted into the valve opening degree, wherein the valve opening degree value L is calculated through a valve opening degree formula. The method is easy to operate and convenient to modify, the modifying cost of the old electric valve is low, and the construction period and cost of modifying and upgrading of the valve are greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of valve opening feedback, and in particular relates to a method for converting valve opening by using resistance. Background Art

[0002] Due to the current rapid development trend of automated control, pipeline valves are gradually moving towards remote control and automatic adjustment control, which requires a monitoring function based on the valve opening. However, the old electric switch valves do not have the valve opening feedback function. If the valves are upgraded and renovated, there will be problems such as long construction period and high cost, which will also affect production. Summary of the invention

[0003] The purpose of the present invention is to provide a method for converting valve opening by using resistance to solve the problems existing in the prior art.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A method for converting valve opening by using resistance comprises the following steps:

[0006] (1) Line modification: Connect the middle end of the sliding rheostat R2 in the electric actuator of the valve to the PLC module, and connect the -V end of the sliding rheostat R2 in series with the resistor R1 before connecting to the PLC module;

[0007] (2) Resistance value converted to temperature value: obtain the maximum temperature T by switching the valve max , minimum temperature T min , Valve limit maximum opening L max , and obtain the real-time temperature value T;

[0008] (3) Convert temperature value into valve opening: Calculate the valve opening value L using the valve opening formula.

[0009] Furthermore, in step (1), the resistance of resistor R1 is 100 ohms.

[0010] Furthermore, the minimum temperature T in step (2) min The method of obtaining is: close the valve, the sum of the resistance values ​​of R2 and R1 changes accordingly, use the converter provided by the PLC module to convert the resistance value into a temperature value through program writing, convert the sum of the resistance values ​​of R2 and R1 at this time into a simulated temperature value, and record the temperature value at this time as the minimum temperature T min .

[0011] Furthermore, in step (2), the valve limits the maximum opening L max The method for obtaining is: according to the use requirements or the actual working conditions of the valve, the upper limit of the valve opening is obtained, which is the maximum opening L of the valve. max .

[0012] Furthermore, the maximum temperature T in step (2) max The method for obtaining is: open the valve to the maximum opening L of the valve max , the sum of the resistance values ​​of R2 and R1 changes accordingly. The resistance value is converted into a temperature value by programming using the converter provided by the PLC module. The sum of the resistance values ​​of R2 and R1 at this time is converted into a simulated temperature value. The temperature value recorded at this time is the maximum temperature T max .

[0013] Furthermore, the method for obtaining the real-time temperature value T in step (2) is: using the converter provided by the PLC module to convert the resistance value into a temperature value through program writing, converting the sum of the resistance values ​​of R2 and R1 corresponding to the current opening state of the valve into a simulated temperature value, and recording the temperature value at this time as the real-time temperature value T.

[0014] Furthermore, the valve opening formula in step (3) is:

[0015]

[0016] Where: L is the valve opening value, T is the real-time temperature value, T min is the minimum temperature, L max The maximum opening of the valve is limited by T max is the maximum temperature.

[0017] The present invention has the following beneficial effects:

[0018] 1. The present invention is simple to operate and convenient to modify, and the modification cost of old electric valves is low, which greatly reduces the construction period and cost of valve modification and upgrading.

[0019] 2. The present invention first converts the resistance value into a virtual temperature value, and then uses the valve opening formula to convert the temperature value into the valve opening for feedback, thereby solving the problem that the old electric valve does not have the valve opening feedback function. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of line transformation of the present invention.

[0021] Figure 2 It is a program page diagram for converting resistance value into temperature value in the PLC module of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] Embodiment 1:

[0024] like Figure 1-2 As shown, a method for converting valve opening by using resistance includes the following steps:

[0025] (1) Line modification: Connect the middle end of the sliding rheostat R2 in the valve's electric actuator to the PLC module, and connect the -V end of the sliding rheostat R2 to the PLC module after being connected in series with a 100-ohm resistor R1.

[0026] (2) Resistance value converted to temperature value: obtain the maximum temperature T by switching the valve max , minimum temperature T min , Valve limit maximum opening L max , and obtain the real-time temperature value T.

[0027] Minimum temperature T min The method of obtaining is: close the valve, the sum of the resistance values ​​of R2 and R1 changes accordingly, use the converter provided by the PLC module to convert the resistance value into a temperature value through program writing, convert the sum of the resistance values ​​of R2 and R1 at this time into a simulated temperature value, and record the temperature value at this time as the minimum temperature T min .

[0028] Valve limit maximum opening L max The method for obtaining is: according to the use requirements or the actual working conditions of the valve, the upper limit of the valve opening is obtained, which is the maximum opening L of the valve. max .

[0029] Maximum temperature T max The method for obtaining is: open the valve to the maximum opening L of the valve max , the sum of the resistance values ​​of R2 and R1 changes accordingly. The resistance value is converted into a temperature value by programming using the converter provided by the PLC module. The sum of the resistance values ​​of R2 and R1 at this time is converted into a simulated temperature value. The temperature value recorded at this time is the maximum temperature T max .

[0030] The method for obtaining the real-time temperature value T is as follows: using the converter provided by the PLC module to convert the resistance value into a temperature value through program writing, converting the sum of the resistance values ​​of R2 and R1 corresponding to the current opening state of the valve into a simulated temperature value, and recording the temperature value at this time as the real-time temperature value T.

[0031] (3) Convert temperature value into valve opening: Calculate the valve opening value L using the valve opening formula.

[0032] The valve opening formula is:

[0033]

[0034] Where: L is the valve opening value, T is the real-time temperature value, T min is the minimum temperature, L max The maximum opening of the valve is limited by T max is the maximum temperature.

[0035] In this embodiment, the valve limits the maximum opening L max The value of R2 is 100, and the valve is opened to 100. At this time, the sum of the resistance values ​​of R2 and R1 is 188.292 ohms. The converter in the PLC module converts it into a virtual temperature of 234°C. The temperature at this time is recorded as the maximum temperature T max =234℃. Close the valve, and the sum of the resistance values ​​of R2 and R1 is 130.133 ohms. The converter in the PLC module converts it into a virtual temperature of 78℃. The temperature at this time is recorded as the minimum temperature T min =78℃.

[0036] In normal use, the real-time opening range of the valve is between 0-100. For example, the sum of the resistance values ​​of R2 and R1 at a certain moment is 172.173 ohms. The converter in the PLC module converts it into a virtual temperature of 190°C, and the real-time temperature value T = 190°C. According to the valve opening formula:

[0037]

[0038] The calculated valve opening value L=71.79 is fed back and can be visualized on the display screen.

[0039] Embodiment 2:

[0040] This embodiment provides a method for converting valve opening by using resistance. The method steps are basically the same as those in Embodiment 1. The difference is that the process requires that the valve is only allowed to be opened to 90 degrees or the valve is stuck and can only be opened to 90 degrees, that is, the valve limits the maximum opening L max =90, open the valve to 90, at this time the sum of the resistance values ​​of R2 and R1 is 179.528 ohms, the converter in the PLC module converts it into a virtual temperature of 210°C, and the temperature at this time is recorded as the maximum temperature T max =210℃. Close the valve, and the sum of the resistance values ​​of R2 and R1 is 130.133 ohms. The converter in the PLC module converts it into a virtual temperature of 78℃. The temperature at this time is recorded as the minimum temperature T min =78℃.

[0041] In normal use, the real-time opening range of the valve is between 0-90. For example, the sum of the resistance values ​​of R2 and R1 at a certain moment is 149.832 ohms. The converter in the PLC module converts it into a virtual temperature of 130°C, and the real-time temperature value T = 130°C. According to the valve opening formula:

[0042]

[0043] The calculated valve opening value L=35.45 is fed back and can be visualized on the display screen.

[0044] The working principle of the present invention is:

[0045] The current mainstream PLC, DCS, RTD or analog input modules can process PT100 resistance signals. Their built-in programs can convert resistance values ​​into temperature values, and have a linear relationship. The corresponding temperature is 0°C when 100 ohms, and the temperature rises by 1°C for every 0.385 ohms increase. At the same time, the electric actuator of the electric valve usually has a sliding rheostat, and different valve openings correspond to different resistance values. This function is used to develop a logic algorithm to convert the resistance value into a virtual temperature value first, and then use the valve opening formula to convert the temperature value into the valve opening for feedback, thereby solving the problem that the old electric valve does not have the valve opening feedback function.

[0046] Compared with the existing method of upgrading the opening feedback function of old electric switch valves, by using resistance to convert the valve opening, the valve opening can be visualized without replacing the equipment, which can greatly reduce the construction period and cost of valve upgrading.

[0047] The above embodiments are only for describing the preferred implementation of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should fall within the protection scope of the present invention.

[0048] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A method for converting valve opening using resistance, characterized in that: The following steps are involved: (1) Line modification: Connect the middle end of the sliding rheostat R2 in the electric actuator of the valve to the PLC module, and connect the -V end of the sliding rheostat R2 in series with the resistor R1 before connecting to the PLC module; (2) Resistance value converted to temperature value: obtain the maximum temperature T by switching the valve max , minimum temperature T min , Valve limit maximum opening L max , and obtain the real-time temperature value T; (3) Convert temperature value into valve opening: Calculate the valve opening value L using the valve opening formula.

2. The method for converting valve opening by using resistance according to claim 1, characterized in that: The resistance of the resistor R1 in step (1) is 100 ohms.

3. The method for converting valve opening by using resistance according to claim 2, characterized in that: Step (2) The minimum temperature T min The method of obtaining is: close the valve, the sum of the resistance values ​​of R2 and R1 changes accordingly, use the converter provided by the PLC module to convert the resistance value into a temperature value through program writing, convert the sum of the resistance values ​​of R2 and R1 at this time into a simulated temperature value, and record the temperature value at this time as the minimum temperature T min .

4. The method of using resistance to convert valve opening according to claim 2, characterized in that: The valve in step (2) limits the maximum opening L max The method for obtaining is: according to the use requirements or the actual working conditions of the valve, the upper limit of the valve opening is obtained, which is the maximum opening L of the valve. max .

5. The method for converting valve opening by using resistance according to claim 4, characterized in that: The maximum temperature T in step (2) max The method for obtaining is: open the valve to the maximum opening L of the valve max , the sum of the resistance values ​​of R2 and R1 changes accordingly. The resistance value is converted into a temperature value by programming using the converter provided by the PLC module. The sum of the resistance values ​​of R2 and R1 at this time is converted into a simulated temperature value. The temperature value recorded at this time is the maximum temperature T max .

6. The method of converting valve opening by using resistance according to claim 2, characterized in that: The method for obtaining the real-time temperature value T in step (2) is: using the converter provided by the PLC module to convert the resistance value into a temperature value through program writing, converting the sum of the resistance values ​​of R2 and R1 corresponding to the current opening state of the valve into a simulated temperature value, and recording the temperature value at this time as the real-time temperature value T.

7. The method of converting valve opening by using resistance according to claim 1, characterized in that: The valve opening formula in step (3) is: Where: L is the valve opening value, T is the real-time temperature value, T min is the minimum temperature, L max The maximum opening of the valve is limited by T max is the maximum temperature.

Images