An improved detection method for oil tank external waveguide liquid level switch

Abstract

The present invention proposes an improved oil tank external waveguide liquid level switch detection method, comprising the following steps: step 1, respectively pasting a waveguide excitation element and a waveguide sensor element at the liquid level height to be detected in the oil tank; step 2, when the oil tank liquid level is lower than the liquid level height to be detected, collecting and saving a low reference signal; step 3, when the oil tank liquid level is higher than the liquid level height to be detected, collecting and saving a high reference signal; step 4, in the process of oil tank liquid level change, judging whether the liquid level in the oil tank has reached the detection height according to the waveguide signal, thereby, the present invention compares the mutual relationship and threshold between the waveguide signal when the liquid level has not reached the liquid level detection height, the waveguide signal when the liquid level has exceeded the liquid level detection height, and the waveguide signal when the liquid level changes, to determine whether the liquid level has reached the detection height, thereby having the advantage of reducing the possibility of misjudgment of the waveguide liquid level switch caused by the influence of environmental noise.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid level detection, and in particular relates to an improved oil tank externally attached waveguide liquid level switch detection method. Background Art

[0002] At present, the oil tank level is an important control parameter in oil depot management. GB 50074-2014 "Petroleum Depot Design Specification" and GB 50737-2011 "Petroleum Reserve Design Specification" clearly stipulate that the capacity is greater than 100m 3 The storage tanks should be equipped with liquid level alarm devices. At present, the commonly used liquid level switches in oil depots are: float type liquid level switch, capacitive liquid level switch, tuning fork type liquid level switch, photoelectric liquid level switch, ultrasonic liquid level switch, waveguide liquid level switch, etc. Among them, the waveguide liquid level switch does not require holes to be opened on the tank wall, does not require tank cleaning, hot work, and is very convenient to adjust the detected liquid level height, which has attracted the attention of many scholars. However, the influence of environmental noise can cause the waveguide liquid level switch to misjudge, thereby affecting the detection of the liquid level. Summary of the invention

[0003] The present invention provides an improved oil tank external waveguide liquid level switch detection method to solve the above problems.

[0004] The technical solution of the present invention is implemented as follows: an improved oil tank external waveguide liquid level switch detection method comprises the following steps:

[0005] Step 1: Paste the waveguide excitation element and the waveguide sensor element respectively at the liquid level height to be detected in the oil tank;

[0006] Step 2: When the liquid level in the oil tank is lower than the liquid level height to be detected, collect and save the low reference signal;

[0007] Step 3: When the liquid level in the oil tank is higher than the liquid level height to be detected, collect and save the high reference signal;

[0008] Step 4: During the change of the oil tank liquid level, determine whether the liquid level in the oil tank reaches the detection height based on the guided wave signal.

[0009] As a preferred implementation, in step 1, the pasting positions of the waveguide excitation element and the waveguide sensor element are both located outside the oil tank, and the waveguide excitation element and the waveguide sensor element are arranged on the same horizontal plane.

[0010] As a preferred embodiment, a detection system is provided on one side of the oil tank, and the detection system and the waveguide excitation element and the waveguide sensing element are electrically connected to store and calculate the waveguide signal.

[0011] As a preferred embodiment, the method for collecting and saving the low reference signal in step 2 is that the waveguide excitation element excites the waveguide signal in the oil tank wall, and the sensor element is used to collect the waveguide signal propagating in the oil tank wall. The waveguide detection signal at this time is used as the low reference signal and is marked as f 0 (t), t is the sampling time of the detection signal, and the low reference signal is stored in the detection system.

[0012] As a preferred embodiment, the method for collecting and saving the high reference signal in step 3 is that the waveguide excitation element excites the waveguide signal in the oil tank wall, and the sensor element is used to collect the waveguide signal propagating in the oil tank wall. The waveguide detection signal at this time is used as the high reference signal, marked as f 1 (t), t is the sampling time of the detection signal, and the high reference signal is stored in the detection system.

[0013] As a preferred implementation, the method for determining whether the liquid level in the oil tank reaches the detection height according to the guided wave signal in step 4 comprises the following steps:

[0014] Step 40: The waveguide excitation element excites a waveguide signal in the oil tank wall, and the sensor element collects the waveguide signal propagating in the oil tank wall. The detection signal at this time is marked as f(t);

[0015] Step 41: Calculate the detection signal f(t) and the low reference signal f using the detection system 0 (t), high reference signal f 1 (t) correlation coefficient;

[0016] Step 42: Compare the correlation coefficient with the threshold value to determine whether the liquid level has reached the liquid level height required to be detected.

[0017] As a preferred embodiment, the detection system is used to calculate the detection signal f(t) and the low reference signal f 0 (t), high reference signal f 1 The calculation formula of the correlation coefficient of (t) is:

[0018]

[0019]

[0020] Among them, R 0 The detection signal f(t) and the low reference signal f 0 (t) correlation coefficient, R 1 The detection signal f(t) and the high reference signal f 1 (t) Correlation coefficient.

[0021] As a preferred implementation, the threshold is divided into a low reference signal threshold and a high reference signal threshold, wherein the low reference signal threshold is set to 0.3, and the high reference signal threshold is set to 0.7.

[0022] As a preferred embodiment, the method for judging whether the liquid level has reached the liquid level height required to be detected is as follows: 0 <0.3, and R 1 When the value is greater than 0.7, it is determined that the liquid level has reached the height required to be detected; otherwise, it is determined that the liquid level has not reached the height required to be detected.

[0023] After adopting the above technical solution, the beneficial effects of the present invention are:

[0024] 1. The present invention uses the technical means of pasting a waveguide excitation element and a waveguide sensor element at the location where the liquid level needs to be detected on the outside of the oil tank, and compares the relationship and threshold between the waveguide signal when the liquid level does not reach the detection height, the waveguide signal when the liquid level exceeds the detection height, and the waveguide signal when the liquid level changes, to determine whether the liquid level has reached the detection height, thereby reducing the possibility of misjudgment of the waveguide liquid level switch caused by the influence of environmental noise.

[0025] 2. The technical means adopted by the present invention are simple and easy to operate, which is helpful to promote the safe management of oil tanks. At the same time, by adjusting the pasting position of the waveguide excitation element and the waveguide sensor element, it is convenient to adjust the detected liquid level height. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 It is a flow chart for the implementation of the present invention;

[0028] Figure 2 It is a schematic diagram of a low reference signal;

[0029] Figure 3 is a schematic diagram of a high reference signal;

[0030] Figure 4 This is the detection signal diagram when the liquid level is 1.6 meters;

[0031] Figure 5 This is the detection signal diagram when the liquid level reaches 2 meters. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] according to Figure 1 As shown, an improved oil tank external waveguide liquid level switch detection method includes the following steps:

[0034] Step 1: Paste the waveguide excitation element and the waveguide sensor element respectively at the liquid level height to be detected in the oil tank;

[0035] Step 2: When the liquid level in the oil tank is lower than the liquid level height to be detected, collect and save the low reference signal;

[0036] Step 3: When the liquid level in the oil tank is higher than the liquid level height to be detected, collect and save the high reference signal;

[0037] Step 4: During the change of the oil tank liquid level, determine whether the liquid level in the oil tank reaches the detection height based on the guided wave signal.

[0038] In step 1, the pasting positions of the waveguide excitation element and the waveguide sensing element are both located outside the oil tank, and the waveguide excitation element and the waveguide sensing element are arranged on the same horizontal plane.

[0039] A detection system is arranged on one side of the oil tank, and the detection system is electrically connected to the waveguide excitation element and the waveguide sensing element for storing and calculating the waveguide signal.

[0040] The method for collecting and saving the low reference signal in step 2 is that the waveguide excitation element excites the waveguide signal in the oil tank wall, and the sensor element is used to collect the waveguide signal propagating in the oil tank wall. The waveguide detection signal at this time is used as the low reference signal and is marked as f 0 (t), t is the sampling time of the detection signal, and the low reference signal is stored in the detection system.

[0041] The method for collecting and saving the high reference signal in step 3 is that the waveguide excitation element excites the waveguide signal in the oil tank wall, and the sensor element is used to collect the waveguide signal propagating in the oil tank wall. The waveguide detection signal at this time is used as the high reference signal and is marked as f 1 (t), t is the sampling time of the detection signal, and the high reference signal is stored in the detection system.

[0042] The method for determining whether the liquid level in the oil tank reaches the detection height according to the guided wave signal in step 4 comprises the following steps:

[0043] Step 40: The waveguide excitation element excites a waveguide signal in the oil tank wall, and the sensor element collects the waveguide signal propagating in the oil tank wall. The detection signal at this time is marked as f(t);

[0044] Step 41: Calculate the detection signal f(t) and the low reference signal f using the detection system 0 (t), high reference signal f 1 (t) correlation coefficient;

[0045] Step 42: Compare the correlation coefficient with the threshold value to determine whether the liquid level has reached the liquid level height required to be detected.

[0046] Use the detection system to calculate the detection signal f(t) and the low reference signal f 0 (t), high reference signal f 1 The calculation formula of the correlation coefficient of (t) is:

[0047]

[0048]

[0049] Among them, R 0 The detection signal f(t) and the low reference signal f 0 (t) correlation coefficient, R 1 The detection signal f(t) and the high reference signal f 1 (t) Correlation coefficient.

[0050] The threshold is divided into a low reference signal threshold and a high reference signal threshold, wherein the low reference signal threshold is set to 0.3 and the high reference signal threshold is set to 0.7.

[0051] The method for judging whether the liquid level has reached the required liquid level height is as follows: 0 <0.3, and R 1 When the value is greater than 0.7, it is determined that the liquid level has reached the height required to be detected; otherwise, it is determined that the liquid level has not reached the height required to be detected.

[0052] In this embodiment, the oil tank switch adopts a vertical metal oil tank, the waveguide excitation element and the waveguide sensing element both adopt PZT-5A piezoelectric sensor, the detection system adopts a waveguide detector, the liquid level height to be detected is 2 meters, the low reference signal threshold is set to 0.3, and the high reference signal threshold is set to 0.7. The present invention is further described as follows:

[0053] Two PZT-5A piezoelectric sensors are pasted on the outer side of the tank wall of a vertical metal oil tank at a liquid level height of 2 meters, with a distance of 0.2 meters between them, serving as the excitation element and sensing element of the waveguide respectively.

[0054] When the oil tank liquid level is 0.5 meters, the waveguide excitation element excites the waveguide signal in the tank wall, and the sensor element is used to collect the waveguide signal propagating in the tank wall. Figure 2 As shown, this signal is used as a low reference signal and is marked as f 0 (t), t is the sampling time of the detection signal. The low reference detection signal is stored in the detection system, that is, it is transmitted to the guided wave detector for storage.

[0055] When the oil tank liquid level is 2.2 meters, the waveguide excitation element again excites the waveguide signal in the tank wall, and the sensor element is used to collect the waveguide signal propagating in the tank wall. Figure 3 As shown, this signal is used as a high reference signal and is marked as f 1 (t), t is the sampling time of the detection signal. The high reference detection signal is stored in the detection system, that is, it is transmitted to the guided wave detector for storage.

[0056] During the change of the tank level, the level switch continuously detects. For example, when the level is 1.6 meters, the detection signal collected is as follows: Figure 4 As shown, the detection signal f(t) and the low reference signal f are calculated. 0 The correlation coefficient R of (t) 0 =0.87; detection signal f(t) and high reference signal f 1 The correlation coefficient R of (t) 1 =0.17. Here, (R 0 =0.87)>0.3, (R 1 =0.17)<0.7, it is judged that the liquid level has not reached the detection height, and the detection continues.

[0057] When the liquid level reaches 2 meters, the collected detection signal is as follows Figure 5 As shown, the detection signal f(t) and the low reference signal f are calculated. 0 Correlation coefficient R of (t) 0 =0.15; detection signal f(t) and high reference signal f 1 Correlation coefficient R of (t) 1 =0.81. Here, (R 0 =0.15)<0.3, and (R 1 =0.81)>0.7, it is judged that the liquid level has reached the detection height.

[0058] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0059] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An improved oil tank external waveguide liquid level switch detection method, characterized in that: The steps include: Step 1: Paste the waveguide excitation element and the waveguide sensor element respectively at the liquid level height to be detected in the oil tank; Step 2: When the liquid level in the oil tank is lower than the liquid level height to be detected, collect and save the low reference signal; Step 3: When the liquid level in the oil tank is higher than the liquid level height to be detected, collect and save the high reference signal; Step 4: During the change of the oil tank liquid level, determine whether the liquid level in the oil tank reaches the detection height according to the guided wave signal; The method for determining whether the liquid level in the oil tank reaches the detection height according to the guided wave signal in step 4 comprises the following steps: Step 40: The waveguide excitation element excites a waveguide signal in the oil tank wall, and the sensor element collects the waveguide signal propagating in the oil tank wall. The detection signal at this time is marked as f(t); Step 41, using the detection system to calculate the correlation coefficient between the detection signal f(t) and the low reference signal f0(t) and the high reference signal f1(t); Step 42: Compare the correlation coefficient with the threshold value to determine whether the liquid level has reached the liquid level height required to be detected.

2. According to claim 1, the improved oil tank external waveguide liquid level switch detection method is characterized in that: In the step 1, the pasting positions of the waveguide excitation element and the waveguide sensing element are both located outside the oil tank, and the waveguide excitation element and the waveguide sensing element are arranged on the same horizontal plane.

3. The improved oil tank external waveguide liquid level switch detection method according to claim 1 is characterized in that: A detection system is arranged on one side of the oil tank, and the detection system and the waveguide excitation element and the waveguide sensing element are electrically connected to each other for storing and calculating the waveguide signal.

4. The improved oil tank external waveguide liquid level switch detection method according to claim 3 is characterized in that: The method for collecting and saving the low reference signal in step 2 is that the waveguide excitation element excites the waveguide signal in the oil tank wall, and the sensor element is used to collect the waveguide signal propagating in the oil tank wall. The waveguide detection signal at this time is used as the low reference signal, marked as f0(t), t is the sampling time of the detection signal, and the low reference signal is saved in the detection system.

5. The improved oil tank external waveguide liquid level switch detection method according to claim 4 is characterized in that: The method for collecting and saving the high reference signal in step 3 is that the waveguide excitation element excites the waveguide signal in the oil tank wall, and the sensor element is used to collect the waveguide signal propagating in the oil tank wall. The waveguide detection signal at this time is used as the high reference signal, marked as f1(t), t is the sampling time of the detection signal, and the high reference signal is saved in the detection system.

6. The improved oil tank external waveguide liquid level switch detection method according to claim 1 is characterized in that: The calculation formula for calculating the mutual correlation coefficient between the detection signal f(t) and the low reference signal f0(t) and the high reference signal f1(t) using the detection system is: ; Wherein, R0 is the correlation coefficient between the detection signal f(t) and the low reference signal f0(t), and R1 is the correlation coefficient between the detection signal f(t) and the high reference signal f1(t).

7. The improved oil tank external waveguide liquid level switch detection method according to claim 1 is characterized in that: The threshold is divided into a low reference signal threshold and a high reference signal threshold, wherein the low reference signal threshold is set to 0.3 and the high reference signal threshold is set to 0.

7.

8. The improved oil tank external waveguide liquid level switch detection method according to claim 6 is characterized in that: The method for judging whether the liquid level has reached the liquid level height required to be detected is that when R0 < 0.3 and R1 > 0.7, it is judged that the liquid level has reached the liquid level height required to be detected; otherwise, it is judged that the liquid level has not reached the liquid level height required to be detected.

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