Anti-corrosion Lining Breakage Detection and Warning Method and Device for Transport Vehicle Tank

Abstract

The present invention discloses a method and a device for detecting and warning of the corrosion-resistant lining breakage of a transport vehicle tank body. The method is to insert an anti-corrosion metal detection rod into the liquid contained in the transport vehicle tank body, regard the space between the anti-corrosion metal detection rod and the metal shell of the tank body as a capacitor, connect it in series with a detection resistor, detect the voltage drop across the detection resistor by applying an alternating voltage, design a circuit by estimating the capacitance of the capacitor, and give a warning if the voltage drop across the detection resistor exceeds the set safety voltage drop value. The present invention ingeniously realizes the detection and warning of the lining breakage from the perspective of the capacitor and the dielectric loss tangent. The method is simple, low in cost, and easy to industrialize.

Description

Technical Field

[0001] The present invention belongs to the technical field of tank safety of transport vehicles, and relates to a method and device for detecting and warning damage of an anti-corrosion lining of a tank of a transport vehicle. Background Art

[0002] The tanks of hazardous chemical transport vehicles are usually steel-lined plastic tanks. A linear low-density modified polyethylene (LLDPE) lining is set inside the steel shell. The lining thickness can reach 15-20mm, which makes the tank body have the strength and pressure resistance of steel containers, and the corrosion resistance and impact resistance of all-plastic and rubber products. If the lining is damaged or about to be damaged, it will be extremely detrimental to the safety of the transport vehicle. Therefore, it is necessary to provide a low-cost, easy-to-operate and industrializable lining damage detection method and device. Summary of the Invention

[0003] The purpose of the present invention is to address the deficiencies in the existing technology and provide a method and device for detecting and warning of damage to the anti-corrosion lining of a transport vehicle tank, which realizes detection and warning of lining damage from the perspective of the capacitor and dielectric loss incision angle.

[0004] A method for detecting and warning of damage to the anti-corrosion lining of a transport vehicle tank involves inserting an anti-corrosion metal detector rod into the liquid contained within the tank. The area between the anti-corrosion metal detector rod and the metal shell of the tank is treated as a capacitor connected in series with a detection resistor. An alternating voltage is applied to detect the voltage drop across the detection resistor. A circuit is designed by estimating the capacitance of the capacitor and setting a safe voltage drop value. This circuit generates a warning if the voltage drop across the detection resistor exceeds the safe voltage drop value. The safe voltage drop value is set based on the capacitive current of the capacitor; a warning is issued as long as the current flowing through the detection resistor increases relative to the capacitive current.

[0005] A device for detecting and warning damage to the anti-corrosion lining of a transport vehicle tank, comprising a detection and warning display circuit, the detection and warning display circuit comprising a transformer, a first anti-corrosion metal detection rod S1, a tank metal shell connection terminal S4, a resistor R52, an adjustable resistor R51, at least one voltage comparator, a series branch formed by several voltage-dividing resistors, and a warning LED;

[0006] The transformer includes a primary coil L1, and two secondary coils L2 and L3. An AC pulse voltage is applied across L1. L3 is connected in series with an adjustable resistor R51, a resistor R52, and a capacitor formed by S1S4 in sequence to form a detection circuit. The voltage drop across R52 is rectified into DC and connected to one input terminal of the voltage comparator. After being rectified into DC, L2 is connected to one end of a series branch formed by the plurality of voltage-dividing resistors. The other end of the series branch is grounded, and at least one non-endpoint of the series branch is connected to the other input terminal of the voltage comparator. The output terminal of the voltage comparator is connected to a warning LED.

[0007] The device further includes a second anti-corrosion metal detection rod S2, a third anti-corrosion metal detection rod S3, and a frequency selection circuit. The second and third anti-corrosion metal detection rods S2 and S3 both independently extend into the liquid contained in the tank body. The frequency selection circuit selects and outputs different frequencies as the operating frequency of the transformer according to the different orders of magnitude of the liquid conductivity between S2 and S3.

[0008] Further, the device is powered by a dry battery DC supply, which can supply 6V. The turns ratio of the coils L1, L2, and L3 of the transformer is preferably 1:1:6. The device may further include a timing control circuit for controlling the start and stop of the device.

[0009] Further, the frequency selection circuit outputs frequencies of 1KHz, 5KHz, 25KHz, and 50KHz in sequence according to the liquid conductivity order of magnitude between S2 and S3 from 10 -1 ~10 -4 S / m.

[0010] The solution of the present invention starts from the perspective of the tangent of the dielectric loss angle of the capacitor. The transport vehicle tank body is regarded as a capacitor. If the inner lining of the tank body is damaged, it will inevitably cause a resistive current in the capacitor, thereby leading to an increase in the current on the series resistor of the capacitor. Thus, a circuit can be designed to detect the voltage drop across the series resistor and compare it with a preset safe voltage drop value to play a warning and detection role. The method and the designed device of the present invention have achieved good results in specific practice, and the method has low cost and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic structural principle diagram of the device of the present invention;

[0012] Figure 2 is a schematic structural diagram of the device of the present invention;

[0013] Figure 3 is a schematic diagram of the relationship between capacitive current and resistive current;

[0014] Figure 4is a schematic diagram of the device of the present invention;

[0015] Figure 5 is a schematic diagram of a specific control circuit of the present invention; Detailed implementation mode

[0016] The technical solution of the present invention will be further described in detail below with reference to examples.

[0017] The transport vehicle tank often needs to transport various liquids, and usually corrosive liquids. When the linear low-density polyethylene of the tank is intact and undamaged, the corrosive liquid and the metal shell of the tank truck can be regarded as forming a capacitor (regarding the corrosive liquid as a conductor) under the isolation of linear low-density polyethylene. Its dielectric constant and dielectric loss tangent angle are close to those of linear low-density polyethylene:

[0018] * Dielectric constant (2.3 - 2.8)

[0019] * Dielectric loss tangent angle: (0.005 - 0.006)

[0020] However, after the linear low-density polyethylene is damaged, it will inevitably cause local or fine leakage. These leakages will change the determined dielectric constant and dielectric loss tangent angle. Therefore, the damage of the tank isolation layer can be detected and warned from the perspective of the dielectric loss tangent angle.

[0021] Combined with Figures 1-3 , S1, S2, and S3 are each connected to a titanium alloy detection rod inserted into the liquid contained in the tank, and S4 is connected to the metal shell of the tank. Then, a capacitor Cx is formed between S1 and S4, and its dielectric is polyethylene and the liquid. When the polyethylene is damaged, it is equivalent to connecting a resistor, i.e., Rx, across the two ends of the capacitor Cx. The capacitance value of the capacitor can be obtained by triple integral. Through the cylindrical capacitance calculation formula: c = ErEoS / d; Er = 2; (It is found from the data that the dielectric constant of linear low-density polyethylene is 1.9 - 2), and Eo = 8.86×10 -12 , combined with the dimensions of the hazardous chemicals transport vehicle tank, the capacitance C is estimated to be 0.084 uF. Since the liquid cannot be completely filled, its capacitance is roughly taken as:

[0022] C = 2 / 3 × 0.084 uF = 0.056 uF.

[0023] According to the relevant principle of the dielectric loss tangent angle, this capacitor is connected in series with the resistor R52, and an AC pulse voltage is applied. Then, there is a current Icx flowing through R52. When the dielectric is damaged, there is a resistive current Irx. The relationship between Icx and Irx is an orthogonal relationship, and it satisfies with the actual current Im flowing through R52: Im 2 = Icx 2 + Irx2 , its relationship with the detection frequency is: Im = V3 / (rx - jwc); The current Im in R52 is Figure 3 already vividly shown in. Therefore, taking the magnitude of Icx as the main detection element, as long as the medium is damaged, the current Im on R52 must be greater than Icx; Therefore, design the safety voltage drop value based on Icx, and light up the green LED to inform relevant personnel that there is no damage inside the vehicle tank; Considering the possible influence of external factors, within a certain range above the safety voltage drop value (i.e., the increase of the capacitive current Icx), light up the yellow LED to inform relevant personnel and send a warning signal; Use the magnitude of the orthogonal value of the resistive current Irx and the capacitive current Icx to judge the damage of the inner lining of the hazardous chemical vehicle tank; Light up the red LED and at the same time start the wireless remote control network device to inform relevant parties or personnel nearby and far away with sound and light information.

[0024] During the design and adjustment process of the entire product device, the biggest problem encountered is that the conductivity of various liquids varies greatly and is non-linearly random; Moreover, with the changes in temperature, humidity, and environment, the differences are too large. Therefore, during the on-site debugging of the product device, it is necessary to correct the coefficients of the theoretical formula at any time. Theoretically, Icx and Irx should be in an orthogonal relationship. However, in actual adjustment, due to changes in vehicle models, liquids, and temperatures, we can only make approximate calculations. Considering that the conductivity range of the liquid in the tank body is between 10 -1 ~10 -4 order of magnitude range, the smaller the conductivity of the liquid, the smaller its capacitive effect in the circuit. In order to measure the current as much as possible so that the device can display accurately, it is necessary to increase the frequency of its AC voltage. Therefore, a frequency selection circuit is set in the detection circuit.

[0025] Figure 5 is a specific circuit structure diagram for implementing the present invention. Next, the Figure 5 working mode and principle will be described:

[0026] This device is powered by 4 AA batteries with a supply voltage of 6V. Since it is a single-system independent power supply, it will not interfere with the original vehicle-mounted electronic control. The main part of the entire circuit consists of 7 integrated circuit chips: Ic1, Ic2, Ic3, Ic4, Ic5, Ic6, Ic7 and 5 crystal triodes: Q1, Q2, Q3, Q4, Q5.

[0027] The overall time control structure of two S-R flip-flops composed of Ic1, 74HC00 and a timing chip Ic5 CD4060: The first S-R flip-flop is triggered by the vibration of the vibration switch TYJM when the car starts. That is, when the car starts, TYJM is short-circuited to the ground, pulling down the high level at the R2 and R4 terminals. Through D1, the second S-R flip-flop is also triggered. The first flip-flop conducts Q2 through R49, and the second flip-flop conducts Q4 through R50. When the power supply conducts through Q2, the power supply is applied to the entire system. The power supply then conducts through Q4 and is applied to Ic5 CD4060 alone, causing the timing control circuit to start working. The resistance values of R1, R2, R3, R4, and R5 are 100K, and the resistance values of R49 and R50 are 4.7K. The basic parameter of CD4060 is that A0 is the basic period T = 2S, which is determined by R7 = 10k and C11 = 1uF. To ensure the normal operation of CD4060, C10 = 0.1uF, R6, and R8 = 100K are used to stabilize its working state. After 16 seconds, the A4 output of CD4060 is high level, and through D3 and R17 = 4.7k, Q1 is conducted, resetting the first S-R flip-flop, thereby turning off the power supply of the entire circuit. Since CD4060 is still working, at this time, CD4060 still outputs high levels of A5, A6, A7, A8, and A9, forcibly resetting the first S-R flip-flop (although the car is running and the vibration is still ongoing, but the system does not work and saves power). Until 17 minutes later (1024 / 60 = 17.06), A10 is output, and through D2 and R18 = 4.7K, Q3 is conducted, causing the second S-R flip-flop to be reset, cutting off the working power supply of CD4060, and restoring the entire circuit system to its original state. Q2 and Q4 are 8550, Q1 and Q3 are 8050, and all the diodes D used are 4148.

[0028] A frequency selection circuit is composed of Ic3 and Ic4. The detection and calibration rod of this device is composed of three titanium alloy metal rods with a diameter of 2 mm and a length of 1 m that are resistant to strong corrosion, namely S1, S2, and S3, which are all inserted into the liquid contained in the tank body. S4 is connected to the metal shell of the vehicle. Assuming that the liquid transported in the vehicle tank remains unchanged, that is, the difference range of its conductivity is not very large, and only fixed-frequency detection is used, the detection function can also be realized with an anti-corrosion metal detection rod. If the liquid contained in the transport vehicle tank is not fixed, then the core of the detection part is to know what conductivity liquid this device is detecting, so as to determine what frequency to use for basic detection.

[0029] IC4 LM324 is a 4-op-amp integrated chip. The 4 op-amp circuits form 4 comparators, which respectively output high levels. They are respectively driven by diodes D10, D11, D12, and D13 to generate frequencies 1, 2, 3, and 4, and drive Q5 through R19 = 4.7K, enabling the high-frequency transformer B to enter the working state. In the input signal of IC4 LM324, the voltages across both ends of R37 and R38 will automatically vary between 1V and 5.5V as the detection and calibration rod is inserted into liquids with different conductivities (such as liquid A with a conductivity of nx10-2; liquid B with a conductivity of mx10-3; liquid C with a conductivity of px10-4). R37 = 1K and R38 = 1000K. Among them, the resistance values of R28, 29, 30, and 31 are all 1K, and the diodes used are all 4148. In the comparison circuit, R35 = 5K, R34 = 25K, and R33, R34, R36 = 10K.

[0030] Control Figure 4 As can be seen, the resistance change between S2 and S3 (i.e., the reciprocal of the liquid conductivity) will generate a voltage division on R38 in a 6V DC voltage, and its value will change between 0.54V and 5V in liquids with different conductivities (such as 1.2V for hydrofluoric acid, 3V for sodium hydroxide, 4.8V for sulfuric acid...). Thus, it can be determined that this set of comparison circuits can generate 4 high levels respectively when the detection and calibration rod is immersed in liquids (the conductivity of the liquid is in the range of n×10 -1 ~n×10 -4 range), driving the generation of frequencies 1, 2, 3, and 4, where frequency 1 is 1KHz; frequency 2 is 5KHz; frequency 3 is 25KHz; frequency 4 is 50KHz. Such a frequency distribution is because the smaller the conductivity of the liquid, the smaller the capacitance effect in the circuit. Therefore, it is necessary to increase the frequency to strengthen the capacitance effect, that is: increasing the value of Icx to facilitate the accurate display of the device.

[0031] In Figure 5 : f1 = 1KHz is determined by R20 = 50K and C6 = 0.01uF; f2 = 5KHz is determined by R21 = 10K and C7 = 0.01uF; f3 = 25KHz is determined by R22 = 20K and C8 = 1000pF; f4 = 50KHz is determined by R23 = 10K and C9 = 1000pF.

[0032] In transformer B, L1 is the primary of the original transformer; L2 and L3 are the secondaries of the transformer, and the turns ratio is 1:1:6; L2 generates a 6V DC voltage V2 through rectification to supply the operation of IC6 LM324. After passing through transformer B, V2 and the battery power supply V1 are separated, reducing or isolating the interference between the circuit functions of the two parts, making the overall function of the machine more stable. IC6 LM324 also forms 4 comparators respectively to identify the voltage magnitude on R52 and drive two green LED light-emitting diodes respectively; a yellow LED warning diode; a red LED alarm diode. When the red light-emitting diode is lit, the wireless alarm system is activated to emphasize and inform relevant personnel or departments in the form of sound and light (the technology of this wireless transmission system is very mature today and will not be further introduced or explained here). L3 in transformer B is used as a variable-frequency pulse AC source supply device for detection and calibration, and its application acts on the two ends of S1 and S4. The variable-frequency pulse alternating current Im, (Im = Icx × Irx, where × represents orthogonality). Since the system adopts a complete set of methods of taking the capacitive current of the capacitor as the reference and using an additional anti-corrosion metal detection and calibration rod for sampling during design, when the inner lining of the tank, linear low-density polyethylene becomes thinner (d in the formula c = ErEoS / d decreases), the current Im flowing through R52 increases, the detection and calibration voltage increases, and the yellow LED warning is lit, which is an inevitable result. This is the superiority of this detection device. In Figure 4 it, R24, 25, 26, 27, 43 are 10K; R39, 40, 41, 42, 54, 55, 56, 57 are 1K; R52 = 6k, R53 = 100K, R58 = 10K; C12 = 10uF, C13 = 22uF, and R51 is a variable resistor used to adjust the circuit to meet the circuit requirements. Taking the example of the frequency 4 being conducted by the liquid contained, that is, the detection frequency is f4 = 50Khz. At this time, without considering the damage factor, according to Cx = 1 / 2πfC, the estimated value of the capacitive reactance of the capacitor is 60 ohms, then the capacitive current is Icx = U / Cx. According to Figure 5 the design in, the voltage on R52 should be greater than 3.6V for the yellow light to turn on, that is, the capacitive current should reach 0.6mA, then the resistance value of R51 can be basically determined (36V / 0.6mA = 60K ohms, R51 = 60K - 6k - 60 ≈ 54k, that is, when the frequency is 50Khz, R51 takes about 54k. Similarly, the size of R51 can be obtained correspondingly at other frequencies).

[0033] That is, it can be seen that the core of the present invention is to regard the tank body of the transport vehicle as a capacitor, and to use the relevant principles of the capacitor dielectric loss tangent angle, and to use the size of its capacitive current (Icx) as the main factor of detection (however, it is not necessary to obtain its exact size, but only to use it as a judgment benchmark, and to issue an early warning if the current increases on this basis), to light up the green LED, thereby informing the relevant personnel that the tank lining is intact. The increase in the capacitive current (Icx) lights up the yellow LED, notifying the relevant personnel and issuing an early warning signal. If the current increases beyond a certain range (which can be set through experience), it is determined that the lining of the hazardous chemical tank has been damaged, thereby lighting up the red LED, and at the same time starting the wireless remote control network device to inform the relevant parties or personnel near and far with sound and light information.

[0034] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments. Those skilled in the art can choose the component models and parameters on their own; and the present invention can be implemented in other specific circuit forms without departing from the spirit or basic characteristics of the present invention.

Claims

1. A method for detecting and warning of damage to the anti-corrosion lining of a transport vehicle tank, characterized in that, The anti-corrosion metal detection rod is inserted into the liquid contained in the transport vehicle tank. Regarding the space between the anti-corrosion metal detection rod and the metal shell of the tank as a capacitor, the lining breakage of the tank is detected and pre-warned from the perspective of the dielectric loss tangent angle: the capacitor is connected in series with a detection resistor, and an alternating voltage is applied and the voltage drop across the detection resistor is detected. If the voltage drop across the detection resistor exceeds the set safety voltage drop value, a pre-warning is given. The setting of the safety voltage drop value is based on the capacitive current of the capacitor. As long as the current flowing through the detection resistor increases based on the capacitive current, a pre-warning is given; And two other anti-corrosion metal detection rods are provided, both independently inserted into the liquid contained in the tank, and a frequency selection circuit is provided for selecting and outputting different frequencies as the operating frequencies of the detection voltage drop circuit according to the different orders of magnitude of the liquid conductivity between the two anti-corrosion metal detection rods.

2. An anti-corrosion lining damage detection and warning device for the tank body of a transport vehicle, characterized in that, It includes a detection and pre-warning display circuit, and the detection and pre-warning display circuit includes a transformer, a first anti-corrosion metal detection rod S1, a connection end S4 of the tank metal shell, a resistor R52, a variable resistor R51, at least one voltage comparator, and a series branch formed by several voltage dividing resistors, and a pre-warning LED; The transformer includes a primary coil L1 and two secondary coils L2, L3. An alternating pulse voltage is applied across L1. L3 is connected in series with the variable resistor R51, the resistor R52, and the capacitor formed by S1S4 in sequence to form a detection loop. The voltage drop across the resistor R52 is rectified into a direct current and connected to one input end of the voltage comparator. L2 is rectified into a direct current and connected to one end of the series branch formed by the several voltage dividing resistors. The other end of the series branch is grounded. At least one non-endpoint of the series branch is connected to the other input end of the voltage comparator. The output end of the voltage comparator is connected to the pre-warning LED; The device also includes a second anti-corrosion metal detection rod S2, a third anti-corrosion metal detection rod S3, and a frequency selection circuit. The second and third anti-corrosion metal detection rods S2 and S3 are both independently inserted into the liquid contained in the tank. The frequency selection circuit selects and outputs different frequencies as the operating frequencies of the transformer according to the different orders of magnitude of the liquid conductivity between S2 and S3; The device also includes a timing control circuit for controlling the start and stop of the device.

3. The anti-corrosion lining breakage detection and warning device for the transport vehicle tank according to claim 2, characterized in that, The device is powered by a dry battery DC supply.

4. The anti-corrosion lining breakage detection and warning device for the transport vehicle tank according to claim 2, wherein, The frequency selection circuit outputs frequencies of 1 KHz, 5 kHz, 25 KHz, and 50 KHz in sequence according to the liquid conductivity order of magnitude between S2 and S3, which is 10 -1 ~10 -4 S / m.

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