CN106441500A - Electric-conductive liquid level sensor applied to severe environments - Google Patents
Electric-conductive liquid level sensor applied to severe environments Download PDFInfo
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- CN106441500A CN106441500A CN201510491696.7A CN201510491696A CN106441500A CN 106441500 A CN106441500 A CN 106441500A CN 201510491696 A CN201510491696 A CN 201510491696A CN 106441500 A CN106441500 A CN 106441500A
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Abstract
An electric-conductive liquid level sensor applied to severe environments is mainly composed of a multi-probe structure sensing probe with unique design, a transmission cable of which one end connected to the sensing probe adopts a special wire arrangement structure, a remote circuit connected to the other end of the transmission cable, as well as upper computer signal processing and system control software. Through connection of the transmission cable, the remote circuit can be separated from a detected environment; materials of the sensing probe are selected rationally, so that the sensing system is more applicable to the severe application environments such as high-temperature, high-pressure, high-humidity and high-corrosion environments; because of the unique design of the sensing probe and development of related detection algorithms, the system has a function of remote disconnection detection; and because of rational development of the remote circuit, the dynamic response speed and the measurement accuracy of the system are increased effectively, and a corrosion problem caused by thermal and electro-chemical effects in the severe environments is solved effectively.
Description
Technical field
The present invention relates to a kind of fixed-point type Level Detection sensor-based system, more particularly to can be applicable to low cost under the adverse circumstances such as high temperature, high pressure, high humidity, high corrosion, high precision electro conduction liquid level sensor.
Background technology
In process of production, the whether accurate yield directly influencing product of level gauging and quality, the safety producing and production cost.At present, the method for common measurement liquid level mainly has static pressure type, float-type, condenser type, ultrasound wave and conductance type level measuring method.Pressure-type liquidometer is based on the measurement to liquid static pressure, and its certainty of measurement is low, depends on gases used density；Float type level gauge causes float displacement by liquid level change, thus causing the rotation of mechanical part or displacement to realize level gauging, being easily worn or being blocked by dirty thing；Capacitance level gauge is to measure the capacitance variations being caused by liquid level change thus recording liquid level, and it is higher to the design requirement of circuit；Supercritical ultrasonics technology is based on the measurement to ultrasound wave propagation time between liquid surface and ultrasonic detector, and it is more sensitive to the fluctuation of air themperature, pressure and air-flow and liquid surface.Conductance type level gauge is the method obtaining liquid level by measuring the conductance of conducting liquid.Compared to aforesaid several level measuring methods, conductance type liquid level sensor has that structure is simple, frame for movement is stable, dynamic response is good, measuring circuit is simple, comprehensive advantage more low to operating environment requirements.
The definition expression formula of conductance isL=1/R=A/ ρ l=kA/l, wherein,LFor conductance (S)；RFor resistance (Ω)；AFor conductor effective area (m 2 )；ρFor resistivity (Ω· m)；lFor conductor effective length (m)；kFor electrical conductivity (Ω -1 · m -1 ).In actual applications, because conductance type liquidometer sensor probe cross-sectional area is fixing, liquid levelhWith conductor effective areaAIt is directly proportional, and because liquid electric conductivitykWith conductor effective lengthlIt is constant, so liquid levelhChange and conductanceLChange meet linear relationship, the liquid level that the electrical conductivity that available conductance type liquidometer records pushes away actual.
The patent of the domestic conductance type liquid level sensor aspect delivered also is not well solved for the conductance liquid level sensor application problem under the adverse circumstances such as high temperature, high pressure, high humidity, high corrosion.
Content of the invention
For overcoming above-mentioned the deficiencies in the prior art, the present invention proposes a kind of conductance type liquid level sensor being applied under adverse circumstances.Present invention can apply under the adverse circumstances such as high temperature, high pressure, high humidity, high corrosion conducting liquid level gauging, ensure that sensing device has preferable stability, higher sensitivity and a good detection performance, the low cost batch production of achievable device simultaneously.
The technical solution adopted in the present invention is：A kind of conductance type liquid level sensor being applied under adverse circumstances is as shown in figure 1, be characterized in：The remote circuit being connected with the transmission cable other end including the transmission cable that sensor probe is connected with sensor probe and host computer signal processing and system controlling software.
A kind of conductance type liquid level sensor being applied under adverse circumstances, its sensing principle is：There are multiple conductive ions in the liquid of the highly corrosive under high temperature, environment under high pressure, its electrical conductivity is typically higher, and is relatively easy to record；And air and water vapour have the less conductive ions of species, their Conductivity Ratio is relatively low.Therefore, conductance type liquid level sensor can accurately obtain the height of liquid level by the difference measuring electrical conductivity.
A kind of conductance type liquid level sensor being applied under adverse circumstances, relate to the design of sensor probe：For being applied to the level gauging of conducting liquid and the applied environment that high corrosion, high pressure, high humidity, high temperature etc. are severe, pickup probe adopts stainless steel alloy material；For reducing measurement error, sensor probe is made up of the different probe of multiple length；For realizing remote transmission cable and each junction point burn out detection, outside sensor probe detection environment, set up the solid value resistance in parallel with detecting medium equivalent resistance.
A kind of conductance type liquid level sensor being applied under adverse circumstances, relate to the exploitation of remote circuit：Remote circuit mainly includes signal modulation circuit, conductance detection circuit, controls indicating circuit.Wherein, signal modulation circuit is used for producing the modulated signal being conducive to Conductivity detection；Conductance detection circuit is used for the change detecting liquid level change or the electrical conductivity causing that breaks；Indicating circuit is controlled to indicate that according to host computer the signal after correlated digital signals process carries out numerical value and shows and break alarm.
Compared with existing conductance type liquid level detection device, the present invention has following advantage：
（1) use of the installation of isolation circuit and remote cable, ensure that this stable operation under the adverse circumstances such as high temperature, high pressure, high humidity for level monitoring sensor.
（2) sensor probe adopts corrosion resistant stainless steel alloy material, makes this liquid level sensor can be used for monitoring the liquid level with corrosive liquids.
（3) be applied to nonmetal pipeline or the no well of metallic ground.
（4) no floating structure, firm mechanical design structure, sensitivity is high.
（5) it is provided with built-in cable burn out detection function.
（6) this invention adopts alternative structure（Alternating voltage or the DC voltage of frequent commutation）Can reduce galvanic corrosion, and avoid the metal loss that DC voltage causes.
Brief description
Fig. 1 is conductance type liquid level sensor system figure
Fig. 2 is multiple spot conductance type level sensing sonde configuration figure.
Specific embodiment
A kind of conductance type liquid level sensor being applied under adverse circumstances includes the sensor probe being made up of one or more probes, connects transmission cable and the remote circuit of remote circuit.
A kind of conductance type liquid level sensor being applied under adverse circumstances, its overall structure is as shown in figure 1, the triangular wave being produced by circuit, as the positive input of operational amplifier, passes through negative feedback resistor R, triangular wave also serves as the negative input of operational amplifier simultaneously.Remote circuit is connected by transmission cable with sensor probe.In high temperature, high humility or have in the adverse circumstances such as corrosive ion, sensor probe produces DC voltage because of thermal and electrochemical, and the electric capacity between operational amplifier and remote cable is used to stop the associated erosion being produced by the DC voltage that induced charge stream or thermal and electrochemical effect generate.The load of unique conductive present in remote cable is 1) fixing conductive load, or 2) liquid effective conductance under AC signal frequency (usually 500-5000Hz).The output voltage of operational amplifier is the triangle wave voltage that applied and signal voltage（I × R）Summation, wherein I be flow into holding wire electric current, R is the resistance in the feedback path of operational amplifier.Identical triangular wave is delivered to the input of an independent A/D converter, and then can calculate in software, will be proportional to the actual voltage value of the conductance of sensor probe（I × R）Separate with above-mentioned triangle wave voltage value.
A kind of conductance type liquid level sensor being applied under adverse circumstances, the structure of its sensor probe is as shown in Fig. 2 1- reference resistance, 2- transmission cable, 3- metallic substrates, 4- pickup probe, 5- pickup probe, 6- common probe, 7- pickup probe.The left side of figure illustrates section of structure, and the right side of figure clearly show that 4 each probes of independent probe with the air around power contacts or liquid.From being corroded for keeping away, using stainless steel alloy material, such as INCONEL625 or the alloy material of correlation.Although rustless steel can form the oxide-film hindering DC conductivity measurement, when it is used for this invention, thin oxide-film means that it can be equivalent to the big stage capacitors without interference with AC conductivity measurement.Each sensor probe is made up of 4 little probes：Wherein 3 are used for detecting liquid level, the 4th is a common probe, and the length of this common probe is roughly the same with minimum liquid detecting probe, guarantees that at least one probe measures with this.Each probe at various height, to ensure high-acruracy survey to liquid level.The length of detection probe depends on the liquid level of detected liquid, and the length of probe may be as short as several millimeters it is also possible to be up to one meter, and these are all without its detecting function of impact.
In the presence of there is no liquid, admittedly the value of value resistance determines the value of each pickup probe electrical conductivity.Shown in the left hand view of Fig. 2 is how resistance be connected to public sensing line from every sensing line；In actual applications, conductance part is embedded in sensor probe and protects.If cable cut, conductance also will be reduced to zero；Thus built-in conductance can judge to connect whether sensor probe is intact with the cable of testing circuit as pilot signal, the whether damaged real-time detection of cable thus can be realized.Each pickup probe and common probe are each connected on the single covered wire in shielded cable.Shielding construction is not mounted on sensor probe, and is mounted to the common terminal of circuit, to reduce the introducing of noise as electrostatic screen layer.
Remote circuit mainly includes signal modulation circuit, conductance detection circuit, controls indicating circuit, and signal modulation circuit is used for producing the modulated signal being conducive to Conductivity detection, and in enforcement, modulated signal is square-wave signal；Conductance detection circuit is used for the change detecting liquid level change or the electrical conductivity causing that breaks.Coherent signal treatment technology is employed, including peak restrained, the continuous reading asking dynamic average, multiple agreement etc., with the environment noise suppressing overlength cable to cause, it is to avoid reading is not accurate in software.Detection logic in software is used for determining whether that cable failure, liquid exist or drying regime.If there is cable failure or there is liquid, dry contact closes, to drive related circuit to carry out process, display or warning of relevant information etc..
Claims (7)
1. a kind of conductance type liquid level sensor being applied under adverse circumstances, is characterized in that：This conductance type liquid level sensor system is to be the remote circuit being connected with the transmission cable other end using the transmission cable of special wire structures by one end that the multiprobe structure sensor probe with unique design is connected with sensor probe, and host computer signal processing and system controlling software composition.
2. sensor probe according to claim 1 is it is characterised in that it is to be made up of multiple probes, and at least one with minimum probe length identical probe as common probe, mutually insulated between probe, each probe with detect that liquid is on-insulated.
3. sensor probe according to claim 1 is it is characterised in that have fixing resistance as reference, to realize the fault detect of circuit between remote circuit and sensor probe between its each probe and common probe.
4. transmission cable according to claim 1, may be by the DC voltage of heat or electrochemical effect generation in sensor probe, with the corrosion avoiding DC voltage to cause with elimination it is characterised in that having the capacitor being installed in series in its wire structures.
5. it is characterised in that it produces triangle wave voltage, it is applied to all the sensors wire to remote circuit according to claim 1, can be used for measuring the electric charge flowing into every sense line and additional stylet, so that it is determined that conductance.
6. the triangle wave voltage according to belonging to claim 5 be it is characterised in that it can be replaced by the modulated signal of sawtooth waveforms, sine wave signal or correlation, and also has the function of determining conductance in circuit.
7. remote circuit according to claim 1, it is characterised in that it employs coherent signal treatment technology, including peak restrained, seeks dynamic average, the continuous reading of multiple agreements, to suppress to carry out the environment noise that overlength cable causes, it is to avoid reading is not accurate.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510491696.7A CN106441500A (en) | 2015-08-12 | 2015-08-12 | Electric-conductive liquid level sensor applied to severe environments |
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| CN201510491696.7A CN106441500A (en) | 2015-08-12 | 2015-08-12 | Electric-conductive liquid level sensor applied to severe environments |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106930056A (en) * | 2017-03-22 | 2017-07-07 | 无锡小天鹅股份有限公司 | Washing machine and its detergent detection means |
| CN107270996A (en) * | 2017-07-13 | 2017-10-20 | 厦门芯阳科技股份有限公司 | A kind of water level detection circuit and device |
| CN107626197A (en) * | 2017-11-06 | 2018-01-26 | 安徽理工大学 | A kind of thionizer liquid level meter and installation method |
| CN111052758A (en) * | 2017-05-11 | 2020-04-21 | 尼科达公司 | Detection and analysis of the amount of content |
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| CN2519903Y (en) * | 2001-12-28 | 2002-11-06 | 王晓峰 | Liquid level sensor |
| CN1595075A (en) * | 2004-06-18 | 2005-03-16 | 李虬 | Water level measuring apparatus |
| CN202204566U (en) * | 2011-05-28 | 2012-04-25 | 宋玉兴 | Novel liquid level sensor |
| CN102564522A (en) * | 2010-12-16 | 2012-07-11 | 上海宝钢工业检测公司 | Electrode floating type hybrid liquid indicator group with self-diagnosis function |
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2015
- 2015-08-12 CN CN201510491696.7A patent/CN106441500A/en active Pending
Patent Citations (6)
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| JPH09189595A (en) * | 1996-01-09 | 1997-07-22 | Toshiba Joho Seigyo Syst Kk | Apparatus for detecting liquid nonfeeding |
| CN2511951Y (en) * | 2001-11-01 | 2002-09-18 | 王晓峰 | Liquid level sensor |
| CN2519903Y (en) * | 2001-12-28 | 2002-11-06 | 王晓峰 | Liquid level sensor |
| CN1595075A (en) * | 2004-06-18 | 2005-03-16 | 李虬 | Water level measuring apparatus |
| CN102564522A (en) * | 2010-12-16 | 2012-07-11 | 上海宝钢工业检测公司 | Electrode floating type hybrid liquid indicator group with self-diagnosis function |
| CN202204566U (en) * | 2011-05-28 | 2012-04-25 | 宋玉兴 | Novel liquid level sensor |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106930056A (en) * | 2017-03-22 | 2017-07-07 | 无锡小天鹅股份有限公司 | Washing machine and its detergent detection means |
| CN106930056B (en) * | 2017-03-22 | 2020-04-14 | 无锡小天鹅电器有限公司 | Washing machine and detergent detection device thereof |
| CN111052758A (en) * | 2017-05-11 | 2020-04-21 | 尼科达公司 | Detection and analysis of the amount of content |
| CN107270996A (en) * | 2017-07-13 | 2017-10-20 | 厦门芯阳科技股份有限公司 | A kind of water level detection circuit and device |
| CN107626197A (en) * | 2017-11-06 | 2018-01-26 | 安徽理工大学 | A kind of thionizer liquid level meter and installation method |
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Application publication date: 20170222 |