Have and realize level gauging three probe capacitance level gauges measurement tubes of compensation automatically
Technical field
The invention belongs to the liquid level controlling technical scope, particularly can realize on-line automatic compensation measured medium change in dielectric constant, measured medium to the variation of the variation of rapier adhesion rate and gas or steam state medium specific inductive capacity to measurement bring influence a kind of have realize level gauging automatically three probe capacitance level gauges of compensation measure tube.
Background technology:
Traditional capacitance level gauge all adopts single probe measurement mode, and it is by a capacitance measurement probe, and a change send display instrument to add a capacitance measurement rapier formation capacitance type liquid level measuring system.Existing capacitance level gauge is measured the rapier structure type and is comprised: single feeler lever class (rigidity, soft), and near flat, two feeler lever classes, coaxial sleeve formula.Single feeler lever class, near rapier such as flat, when measuring at the scene, need provide another rapier earth polar for referencial use (as tank skin) could constitute complete capacitance measurement rapier.Two feeler lever class rapiers then oneself constitute complete capacitance measurement rapier.Capacitance measurement rapiers such as single feeler lever class, approaching flat, two feeler lever classes all must be installed in the tested container, and measuring system could be implemented to measure.Coaxial sleeve formula rapier be the reference earth polar that constitutes by metal tube with it fully insulation coaxial linking to each other of metal bar rapier constitute complete capacitance measurement rapier, this rapier measuring accuracy height, its installation form is more flexible, as being connected in outside the tested container, also can be directly installed in the tested container by the Communicating device form.E is constant relatively at the measured medium specific inductive capacity, measured medium keeps certain to the rapier adhesion rate, when gas (vapour) attitude medium specific inductive capacity is constant relatively in the capacitance measurement rapier during measurement, the measured capacitance changing value of coaxial sleeve is just only relevant with liquid level change value in the coaxial sleeve, and be proportional relation, through once 2 on-site provings (or simulating the demarcation that the in-site measurement environment carries out), traditional single probe capacitance level gauge can correct measurement measured medium liquid level.Calculate by following formula:
Wherein: H surveys: the level value during measurement.
C surveys: the measurement capacitance when the coaxial sleeve rapier is measured.
C0: measurement capacitance when coaxial sleeve on-site proving state descends empty.
C is full: measurement capacitance when being full of measured medium under the coaxial sleeve on-site proving state.Measured medium liquid level change value.
It is constant relatively that this measuring method is only applicable to measured medium specific inductive capacity e, and measured medium is constant relatively to the adhesion rate of rapier, the constant relatively occasion of gas (vapour) attitude medium specific inductive capacity in capacitance measurement rapier during measurement.Some level gauging site environment changes very complicated, exist the specific inductive capacity of same measured medium and measured medium to the parameters such as adhesion rate of rapier with temperature, change in pressure, these variations will cause the liquid level changing value of the specific capacitance changing value correspondence of surveying and calibration value to produce difference, add gas (vapour) attitude medium change in dielectric constant is measured null value to the coaxial sleeve rapier influence.These influences will cause measuring error, and when this error surpassed measure field measurement maximum error permissible value, traditional single probe capacitance level gauge did not compensate the ability of this influence because of self, just can not be applied in this type of and measure occasion.
Summary of the invention
The purpose of this invention is to provide and to realize on-line automatic compensation measured medium change in dielectric constant, measured medium to the variation of the variation of rapier adhesion rate and gas or steam state medium specific inductive capacity to measurement bring influence a kind of have realize level gauging automatically three probe capacitance level gauges of compensation measure tube, it is characterized in that: it is the low order ends that are higher than the high order end of measured medium liquid level change peak and are lower than measured medium liquid level change minimum point on coaxial sleeve formula measurement rapier that described three probe capacitance level gauges with the automatic compensation of realization level gauging are measured barrel structures, with the cross over pipe form each and connect a coaxial sleeve and measure rapier, promptly by 1#, 2#, three coaxial sleeves of 3# are measured the three probe capacitance level gauges measurement tubes that rapier is connected to form, it is the main tube of measuring that its 1# measures tube, its making height of measuring rapier is as the criterion 2# with the effective measurement range that meets field requirement, the making that the 3# coaxial sleeve is measured rapier highly is sixth to three/one that the 1# coaxial sleeve is measured the making height of rapier; Simultaneously to measure the physical indexs such as reference earth polar metal tube internal diameter, metal bar rapier external diameter, thickness of insulating layer, material of rapiers all consistent for three coaxial sleeves, is used to guarantee that three coaxial sleeves measure rapiers and can measure with a kind of medium simultaneously and to guarantee that three coaxial sleeves are measured the measurement capacitance variations value that causes when rapiers are measured same unit height measured medium liquid level change under equivalent environment in full accord; Its 2# measurement tube will be placed in empty tube forever in actual measurement be the high order end state, be used for that 1#, 3# are measured the empty tube of a tube electric capacity calibration value and revise, it is mainly eliminated the variation of gas or steam state medium specific inductive capacity and measured medium the variation of the adhesion rate of rapier is brought influence to measurement; Its 3# measures tube, and will to be placed in the full tube of measured medium in actual measurement forever be the low order end state, and the full tube electric capacity calibration value that is used for 1# is measured tube is revised, and it mainly eliminates the influence of change in dielectric constant to measuring of measured medium; If three probe capacitance type liquid level measuring tubes are aided with three electrical measurement index unanimities and the good capacitance measurement probe of precision send display instrument with relevant change, have just constituted one and overlapped three probe capacitance level gauges with level gauging automatic compensation function; The liquid level of any liquid medium of measuring with three probe capacitance type liquid level measuring tubes can calculate with two kinds of computing formula, and is consequently identical;
Its first kind of account form: calculate as fixed length with H1, the corresponding liquid level change value of value after the correction of actual measurement capacitance variations when promptly 1# measures tube from empty tube to full tube, forever in H1 calibration value Suan:
Its second kind of account form: calculate as fixed length with H3, the corresponding liquid level change value of value after the correction of actual measurement capacitance variations when promptly 3# measures tube from empty tube to full tube, forever in H3 calibration value Suan:
Before carrying out field survey, we are with any liquid medium (as water), under metastable environment, measurement capacitance and three measured medium maximum level change in elevation of measuring the full capacitance variations correspondence of tube are carried out once 2 demarcation respectively when measuring the empty tube of tube, full tube to three, can obtain the parameter under the demarcation state:
C10: the 1# that probe 1 is measured demarcates measurement capacitance when measuring tube sky tube;
C11: the 1# that probe 1 is measured measures and demarcates measurement capacitance when tube is expired tube;
H1:1# measures the tube measurement capacitance and changes corresponding measured medium liquid level change height from C10 to C11;
C20: the 2# that probe 2 is measured demarcates measurement capacitance when measuring tube sky tube;
C21: the 2# that probe 2 is measured measures and demarcates electric capacity calibration measurements value when tube is expired tube;
H2:2# measures the tube measurement capacitance and changes corresponding measured medium liquid level change height from C20 to C21;
C30: the 3# that probe 3 is measured demarcates measurement capacitance when measuring tube sky tube;
C31: the 3# that probe 3 is measured measures and demarcates measurement capacitance when tube is expired tube;
H3:3# measures the tube measurement capacitance and changes corresponding measured medium liquid level change height from C30 to C31;
D: be the full scale setting value, generally be as the criterion with measure field maximum level changing value.
Below we carry out field survey to any liquid medium, obtained 1#, 2#, 3# tube measurement capacitance respectively.
CX1: 1# tube measurement capacitance during field survey;
CX2: 2# tube measurement capacitance during field survey;
CX3: 3# tube measurement capacitance during field survey;
After obtaining above parameters, can carry out the calculating of H measured value.
In first kind of account form and second kind of account form,
1). complemental air (vapour) attitude medium change in dielectric constant and measured medium to the variation of rapier adhesion rate to measuring the calculating of influence:
Mainly measuring the tube correlation parameter with 2# revises the empty tube of 1#, a 3# measurement tube calibration value, the empty tube of the 2# tube capacitance variations value that its (CX2-C20) causes the variation of rapier adhesion rate for gas (vapour) attitude medium change in dielectric constant and measured medium, because gas (vapour) attitude medium change in dielectric constant and measured medium change proportional to capacitance variation and the measuring height value that the variation of rapier adhesion rate causes, so value was after 3# measured the correction of the empty tube of tube calibration value:
Wherein: C30 is that 3# measures the empty tube demarcation of tube measurement capacitance;
For 3# measures the modified value that the empty tube of tube is demarcated measurement capacitance;
Value was after 1# measured the correction of the empty tube of tube calibration value:
Wherein: C10 is that 1# measures the empty tube demarcation of tube measurement capacitance;
For 1# measures the modified value that the empty tube of tube is demarcated measurement capacitance;
2) compensation measured medium change in dielectric constant is to measuring the calculating of influence:
Mainly measuring the tube correlation parameter with 3# revises the full tube of a 1# measurement tube calibration value.The 3# that its (CX3-C31) causes for the measured medium change in dielectric constant measures the full tube of tube capacitance variations value, because it is proportional that capacitance variation that the measured medium change in dielectric constant causes and measuring height value change, so value was after 1# measured the correction of the full tube of tube calibration value:
Wherein: C11 is that 1# measures the full tube demarcation of tube measurement capacitance;
For 1# measures the modified value that the full tube of tube is demarcated measurement capacitance;
Below all can obtain correct measurement result with any account form.
The invention has the beneficial effects as follows, no matter measured medium specific inductive capacity, measured medium are to the rapier adhesion rate, and how parameter such as gas (vapour) attitude medium specific inductive capacity changes, all can compensate measured medium specific inductive capacity, measured medium automatically to the rapier adhesion rate by above-mentioned arithmetic logic three probe capacitance level gauges, reach the influences of variation to measuring such as gas (vapour) attitude medium specific inductive capacity, correct measurement goes out the measured medium level value; The structural design that three probe capacitance level gauges are measured tube makes capacitance type liquid level measuring realize that on-line automatic compensation measured medium specific inductive capacity, measured medium are to the rapier adhesion rate, and the influence of gas (vapour) attitude medium change in dielectric constant to measuring, this is expanded capacitor formula liquid level controlling technical applications greatly.
Description of drawings:
Fig. 1 is the structural design synoptic diagram that three probe capacitance level gauges are measured tube.
Embodiment:
The present invention for can realize on-line automatic compensation measured medium change in dielectric constant, measured medium to the variation of the variation of rapier adhesion rate and gas or steam state medium specific inductive capacity to measurement bring influence a kind of have realize the level gauging three probe capacitance level gauges measurements tin of compensation automatically.Be the high order end 7 that is higher than measured medium liquid level change peak place and low order end 8 (as shown in Figure 1) office that is lower than measured medium liquid level change minimum point place the 1# coaxial sleeve measure reference earth polar metal tube 1 high order end of rapier and low order end with the cross over pipe form each and connect the 2# coaxial sleeve and measure the reference earth polar metal tube 2 of rapier and the reference earth polar metal tube 3 that the 3# coaxial sleeve is measured rapier, form three probe capacitance level gauges and measure tube.Described 1# coaxial sleeve is measured the center insertion of the reference earth polar metal tube 1 of rapier and is measured rapier 4, and the center of the reference earth polar metal tube 2 of 2# coaxial sleeve measurement rapier is inserted the center of the reference earth polar metal tube 3 of measuring rapier 5 and 3# coaxial sleeve measurement rapier and inserted measurement rapier 6.Its 1# coaxial sleeve is measured the reference earth polar metal tube 1 of rapier, the making of measuring rapier 4 highly generally is as the criterion with the effective measurement range that meets field requirement (>or=), the reference earth polar metal tube 3 of the reference earth polar metal tube 2 of 2# coaxial sleeve measurement rapier, measurement rapier 5 and 3# coaxial sleeve measurement rapier, the making of measurement rapier 6 highly Yuan can be arbitrary values on managing, but the making of 2#, 3# coaxial sleeve measurement rapier highly generally is making sixth to three/one highly of 1# coaxial sleeve measurement rapier in practice; Physical indexs such as the metal tube internal diameter in the reference earth polar of three coaxial sleeve measurement rapiers, metal bar rapier external diameter, thickness of insulating layer, material are all consistent simultaneously.So just guaranteed that three coaxial sleeves measure rapiers and can measure simultaneously with a kind of medium, it is in full accord to have guaranteed that also three coaxial sleeves are measured the measurement capacitance variations value that causes when rapier is measured same unit height measured medium liquid level change under equivalent environment.It is the main tube of measuring that its 1# measures tube; Its 2# measurement tube will be placed in empty tube forever in actual measurement be high order end 7 above states, be used for that 1#, 3# are measured the empty tube of a tube electric capacity calibration value and revise, it is mainly eliminated the variation of gas or steam state medium specific inductive capacity and measured medium the variation of the adhesion rate of rapier is brought influence to measurement; Its 3# measures tube, and will to be placed in the full tube of measured medium in actual measurement forever be low order end 8 following states, and the full tube electric capacity calibration value that is used for 1# is measured tube is revised, and it mainly eliminates the influence of the change in dielectric constant of measured medium to measurement; If three probe capacitance type liquid level measuring tubes are aided with three electrical measurement index unanimities and the good capacitance measurement probe of precision 1# measuring sonde, 2# measuring sonde, the 3# measuring sonde send display instrument with relevant change, have just constituted a cover and had three of the level gauging automatic compensation function capacitance level gauges of popping one's head in; The liquid level of measuring any liquid medium of tube measurement with three probe capacitance level gauges can calculate with two kinds of computing formula, and is consequently identical:
Its first kind of account form: calculate as fixed length with H1, the corresponding liquid level change value of value after the correction of actual measurement capacitance variations when promptly 1# measures tube from empty tube to full tube, forever in H1 calibration value Suan:
Its second kind of account form: calculate as fixed length with H3, the corresponding liquid level change value of value after the correction of actual measurement capacitance variations when promptly 3# measures tube from empty tube to full tube, forever in H3 calibration value Suan:
Before carrying out field survey, we are with any liquid medium (as water), under metastable environment, to have the three probe capacitance level gauges of realizing the level gauging automatic compensation function measure three of tube when measuring the empty tube of tube, full tube measurement capacitance and three measured medium maximum level change in elevation of measuring the full capacitance variations correspondences of tube carry out once 2 demarcation respectively, can obtain the parameter under the demarcation state:
C10: the 1# that probe 1 is measured demarcates measurement capacitance when measuring tube sky tube;
C11: the 1# that probe 1 is measured measures and demarcates measurement capacitance when tube is expired tube;
H1:1# measures the tube measurement capacitance and changes corresponding measured medium liquid level change height from C10 to C11;
C20: the 2# that probe 2 is measured demarcates measurement capacitance when measuring tube sky tube;
C21: the 2# that probe 2 is measured measures and demarcates electric capacity calibration measurements value when tube is expired tube;
H2:2# measures the tube measurement capacitance and changes corresponding measured medium liquid level change height from C20 to C21;
C30: the 3# that probe 3 is measured demarcates measurement capacitance when measuring tube sky tube;
C31: the 3# that probe 3 is measured measures and demarcates measurement capacitance when tube is expired tube;
H3:3# measures the tube measurement capacitance and changes corresponding measured medium liquid level change height from C30 to C31;
D: be the full scale setting value, generally be as the criterion with measure field maximum level changing value.
Below we carry out field survey to any liquid medium, can obtain 1#, 2#, 3# tube measurement capacitance respectively.
CX1: 1# tube measurement capacitance during field survey;
CX2: 2# tube measurement capacitance during field survey;
CX3: 3# tube measurement capacitance during field survey;
In first kind of account form and second kind of account form,
1). complemental air (vapour) attitude medium change in dielectric constant and measured medium to the variation of rapier adhesion rate to measuring the calculating of influence:
Mainly measuring the tube correlation parameter with 2# revises the empty tube of 1#, a 3# measurement tube calibration value, the empty tube of the 2# tube capacitance variations value that its (CX2-C20) causes the variation of rapier adhesion rate for gas (vapour) attitude medium change in dielectric constant and measured medium, because gas (vapour) attitude medium change in dielectric constant and measured medium change proportional to capacitance variation and the measuring height value that the variation of rapier adhesion rate causes, so value was after 3# measured the correction of the empty tube of tube calibration value:
Wherein: C30 is that 3# measures the empty tube demarcation of tube measurement capacitance;
For 3# measures the modified value that the empty tube of tube is demarcated measurement capacitance;
Value was after 1# measured the correction of the empty tube of tube calibration value:
Wherein: C10 is that 1# measures the empty tube demarcation of tube measurement capacitance;
For 1# measures the modified value that the empty tube of tube is demarcated measurement capacitance;
2) compensation measured medium change in dielectric constant is to measuring the calculating of influence: mainly with 3# measurement tube correlation parameter 1# is measured the full calibration value of tube and revise.The 3# that its (CX3-C31) causes for the measured medium change in dielectric constant measures the full tube of tube capacitance variations value, and is proportional because capacitance variation that the measured medium specific inductive capacity causes and measuring height value change, so value was after 1# measured the correction of the full tube of tube calibration value:
Wherein: C11 is that 1# measures the full tube demarcation of tube measurement capacitance;
For 1# measures the modified value that the full tube of tube is demarcated measurement capacitance;
Below all can obtain correct measurement result with any account form.
Illustrate:
Calibration: C10:160F C20:40PF C30:65PF D:4.5 rice
C11:400PF C21:80PF C31:125PF
H1:6 rice H2:1 rice H3:1.5 rice
Field survey: CX1:400PF CX2:45PF CX3:162.5PF
Illustrate: gas (vapour) attitude medium specific inductive capacity and measured medium are 5PF to the variation changing value that capacitance measurement influences to the empty tube of 2# tube of rapier adhesion rate; The measured medium change in dielectric constant is 37.5PF to the changing value of the full tube of 3# tube capacitance measurement influence.
Calculate as fixed length in H1: when promptly 1# measures the tube actual measurement from empty tube to the correction of full tube capacitance variations after the liquid level change value of value correspondence forever with H1 calibration value Suan; First kind of account form is calculated as follows:
Calculate as fixed length in H3: when promptly 3# measures the tube actual measurement from empty tube to the correction of full tube capacitance variations after value to the liquid level change value forever with H3 calibration value Suan; Second kind of calculating formula is calculated as follows:
Above result of calculation shows no matter can both obtain correct measurement result with any account form.