CN2148949Y

CN2148949Y - Self-adapting ultrasonic fluid level meter

Info

Publication number: CN2148949Y
Application number: CN 93203106
Authority: CN
Inventors: 李健之
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-02-17
Filing date: 1993-02-17
Publication date: 1993-12-08
Anticipated expiration: 2003-02-17

Abstract

The utility model provides a self-adapting ultrasonic fluid level meter, which belongs to the technical field of ultrasonic measurement and particularly relates to the detection of the fluid level in the oil tank and other liquid storing container. The utility model is characterized in that a sealing double face probe which is high temperature-proof and acid base-proof is arranged at a fixed position in the measuring conducting pipe, and a set of sending and receiving circuits are processed through special signals to obtain the fluid level value. The utility model has the advantages of self-adapting function and easy installation and solves the problem that the variation of the fluid medium physical parameter has the influence on the measuring result, applied to the detection for the fluid level of the inflammable explosive fluid medium with high temperature, high pressure and strong corrosivity.

Description

Self-adapting ultrasonic fluid level meter

The utility model belongs to the supersonic technique field, relates in particular to thing position and liquid level in the liquid medium under the various operating modes of ultrasonic measurement.

In the production run of oil, chemical system, many industrial liquids are deposited in the various tuns, and need to measure exactly height that is stored in storage liquid in the container or the volume of storing liquid, for the production process control provides accurate parameters.

Adopt in many application scenarios at present and on container, open visual windows, by operating personnel's field observation, this method precision is low, reaction is slow, can't realize the automatic control of industrial process, and to adopt the method for opening form for the basin of some flammable and combustible liquids be dangerous, other has a kind of steel float-type liquid level measuring system, can provide level value in real time, but the density for liquid medium has certain requirement, simultaneously owing to there is mechanical transmission component, its measuring accuracy and reliability are all influenced, and the differential pressure type measuring system has solved this problem to a certain extent, but its mounting structure complexity, the signal transmitting device is installed on measure field, and its application is affected.

The ultrasonic measurement technology is applied to liquid level, level gauging, it is an approach preferably, in early stage the application, probe is placed in the bottom of flow container, sending out receipts by single probe uses, measure ultrasound wave from being transmitted into the time interval T that receives echoed signal,, press following formula and obtain measuring distance H by the velocity of sound C in the fluid to be measured:

H＝CT／2

But the influence of factors such as sound's velocity in liquid C is stressed, temperature, concentration and changing, thereby influence the measuring accuracy of liquid, be sort this problem out, temperature sensor and pressure transducer have been added in some measuring method, obtain the duty parameter of liquid, revise measurement result, but this makes measuring system complicated more.

The method of U.S. Pat Pat4805453 is that ultrasonic probe is installed in container bottom, and a reflecting surface is set on acoustic wave propagation path, and reflecting surface is to the probe mounting distance H _KBe known, measure respectively and transmit and the time interval T of liquid level face echoed signal and the time interval T with the reflecting surface echoed signal of transmitting _K, can obtain liquid level H by following formula:

H＝H _KT／T _K

The problem of this method is that the size of reflecting surface is big to measuring influence, the installation accuracy height that requires, hyperacoustic energy part face of being reflected stops, makes measuring accuracy and measuring distance influenced, emission angle and sensitivity to probe also have certain requirement, and processing technology is relatively stricter.

Chinese patent CN90100692, ultrasonic probe also are installed in container bottom, but adopt the method for additional reference probe, by known fixed range H of reference probe measurement _K, obtain Measuring Time T _KThe problem that exists is that the consistance of two probes is difficult to guarantee, inconvenience is installed, and this system adopts the signal attenuation of gamut internal fixation, make when echoed signal is strong noise signal big to the interference of measuring, and signal is difficult to measure when weak, makes system repeatedly alarm condition occur, needs manual adjustments to arrive suitable damping capacity.

The purpose of this utility model provides a kind of self-adapting ultrasonic liquid level instrument, the design that it is not only being popped one's head in, the structure of system and reflecting surface choose the problem that exists in the existing method that solved, and adopt digital microprocessor technology control operation and deal with data and adopt the programme-controlled gain unit to realize the automatic gain control of system in the gamut scope.

The purpose of this utility model is achieved in that size and the requirement according to the storage liquid container, design the measuring guide that length is suitable, measuring guide can be installed in storage liquid container inside, also available connecting pipe is installed in the outside of storage liquid container, be installed on the measuring guide tube wall of device inside, have the small opening of some, by the small opening liquid medium can freely come in and go out measuring guide; Be installed in the measuring guide of external container, do not open small opening on the tube wall, but by making liquid medium discrepancy measuring guide up and down two communicating pipes, and interior liquid level face of measuring guide and the liquid level face in the container are consistent, the bottom that is contained in externally measured conduit can be higher than the bottom that is equal to or less than the storage liquid container.

Lower Half in measuring guide, a probe support fixed mount is set, ultrasonic probe is installed in the middle of the supporting and mounting bracket, respectively there is a piezoelectric patches transducer upper and lower end face of ultrasonic probe, can make progress simultaneously and downward emission ultrasonic signal, upwards the ultrasonic waves transmitted signal becomes liquid level face echoed signal through the reflection of liquid level face, and the ultrasonic waves transmitted signal is through the reflection of measuring guide bottom downwards, become the Control echo signal, measure transmit and liquid level face echoed signal between time interval T ₁, transmit and the Control echo signal between time T at interval ₂, then the height H of liquid level face can be calculated by following formula

H＝H _O＋H _K＋H ₂(H ₂T ₁)/(T ₂)

H in the formula _OBe the length of ultrasonic probe, H _KBe that the measuring guide bottom is to the distance of storing the liquid container bottom, H ₂Be the distance of ultrasonic probe lower surface to the measuring guide bottom; H _O, H _KAnd H ₂All obtaining when design and installation, all is known quantity, for the measuring guide that is installed in external container, and H when the bottom of measuring guide is higher than the bottom of storing liquid container _K＞0 H when equaling _K=0, the H when bottom of measuring guide is lower than the bottom of storing liquid container _K＜0.

Total system comprises measuring guide, ultrasonic probe, singlechip CPU unit, programme-controlled gain control module, transceiver circuit, power conversion unit, display unit, remote transmitter etc.

Below in conjunction with drawings and Examples the utility model is further specified

Fig. 1 is the measuring system figure of first embodiment.

Fig. 2 is a programme-controlled gain control module electrical schematic diagram.

Fig. 3 is ultrasonic probe and signal waveforms.

Fig. 4 is that signal receives shaping circuit.

Fig. 5 is the scheme of installation of second embodiment.

1 flange among the figure, 2(is horizontal) container, the 3rd, measuring guide; 4 fluids to be measured, 5 small openings, 6 ultrasonic probes; 7 lead-in wires, 8 bottom reflection faces, 9 pilot protection pipes; 10 probe support fixed mounts, 11 programme-controlled gain control modules, 12 remote transmitters; 13 singlechip CPU unit, 14 radiating circuit unit, 15 digital display units; 16; 17 piezoelectric patches, 18 springs, 19 lead-in wires; 20 electric pulse waveforms, 21 ultrasonic emitting signals, 22; 23 reflection wave signals; 24 echo-pulse waveforms, 25 storage liquid, 26(is vertical) container; 27 valves, 28 flanges, 29 measuring guide; 30 lead-in wires, 31 ultrasonic probes, 32 probe fixed supports.

In Fig. 1, measuring guide 3 is installed in the inside of storage liquid container 2, high temperature resistant, acid and alkali-resistance, hermetically sealed ultrasonic probe 6 is defended tenaciously by probe support and is decided frame 10, be fixed in the measuring guide 3, during measurement, singlechip CPU unit 13 at first starts radiating circuit unit 14, send electric pulse to ultrasonic probe 6, the piezoelectric patches 16 and 17 at probe two ends is subjected to producing ultrasound wave behind the electric pulse, propagate to the bottom reflection face 8 of liquid medium liquid level to be measured and measuring guide respectively, and be reflected back into probe, ultrasonic probe 6 is transformed into electric signal with the echo that receives again, send into programme-controlled gain control module 11 along lead-in wire 7, programme-controlled gain control module 11 is subjected to the control of singlechip CPU unit 13, selects suitable yield value, the level appropriate signals is sent into singlechip CPU unit 13 handle, singlechip CPU unit 13 receives the reflection echo electric signal and the liquid level face echo electric signal of measuring guide bottom respectively, by wherein time counting unit draw them and transmit between time interval T ₂And T ₁So, calculate the height H of current liquid level.Singlechip CPU unit 13 is after obtaining measurement result H, data are sent into digital display unit 15, simultaneously with analog quantization as a result, provide 0～5V and 4～20mA simulating signal, handle use (drawing among the figure) for Displaying Meter or data-signal, when measurement result surpasses the limit up and down that sets in advance, can also provide alerting signal, sound or the light warning by alarm unit (not drawing among the figure), in order to make it, be provided with remote transmitter 12 in the system, under the control of singlechip CPU unit 13 in some application of special occasions, measurement result is sent through remote transmitter 12 with the frequency modulation form, received demonstration by master-control room again.

In Fig. 2, programme-controlled gain control module 11 is made of integrated circuit IM-2400 and electric capacity, resistance, and four resistance string are unified into the input end that voltage divider and tap lead to each road of IM-2400, D ₀And D ₁Given by singlechip CPU unit 13, the different level of level of end provides different yield values, and following table is listed D ₀And D ₁The relation of level and gain:

D ₀D ₁Yield value (E go out/E go into)

0 0 100％

1 0 50％

0 1 25％

1 1 12.5％

So just can in the gamut scope of system, realize adaptive automatic gain control.

Fig. 3 illustrates probe and RST, ultrasonic probe 6 is press-sealed in the shell through spring 18 by piezoelectric patches 16,17,19 draw through going between, when probe 6 receives electric pulse 20, piezoelectric patches 16,17 produces ultrasonic signal 21 simultaneously, after measuring guide bottom reflection face and the reflection of liquid level face, probe 6 is received reflection wave signal 22 and 23 again, after changing into electric signal and process gain control unit and signal reception shaping circuit, become echo-pulse 24 and enter single-chip microcomputer COPU unit 13, thereby record time interval T ₂And T ₁

Fig. 4 is an embodiment who receives shaping circuit, adopts two integrated circuit and electric capacity, resistance.

Fig. 5 is second embodiment, external connected vessels type level measuring method is described, this is more common in oil, chemical industry storage liquid container, measuring guide 29 and probe 31 join together through fixed support 32, combine as a whole through flange 28 and storage liquid container again, valve 27 has guaranteed under the state that works online the Installation and Debugging to measuring system, and measuring-signal 30 is sent through going between.

The utility model has the advantage of and adopted measuring guide to introduce with reference to reflecting surface, overcome the impact of the variations such as liquid medium temperature, pressure to measurement result, measuring guide can place in the storage liquid container, also can place the outside, ultrasonic probe is simple in structure, reliable, and measuring system is by Single-chip Controlling, and has designed the programmed gain control circuit, make system have adaptation function, guarantee instrument steady operation in various variation operating modes.

Claims

1, a kind of instrument that is used for liquid medium operating mode measuring liquid level and thing position, it is by measuring guide, ultrasonic probe, the singlechip CPU unit, the programme-controlled gain control module, the radiating circuit unit, digital display unit, signal receives shaping circuit, compositions such as remote transmitter, it is characterized in that: high temperature resistant, acid and alkali-resistance, two end faces up and down of hermetically sealed ultrasonic probe, ultrasonic transducer respectively is housed, probe is fixed on the position of being partial to Lower Half in the measuring guide, measuring guide is installed in storage liquid container inside, have the small opening of some on the tube wall of measuring guide, liquid medium can freely be come in and gone out, the bottom of measuring guide is utilized as one with reference to reflecting surface, the program of measuring is by the singlechip CPU unit controls, and measurement result is shown by digital display unit.

2, the instrument of measuring liquid level according to claim 1 and thing position, it is characterized in that: described measuring guide is installed in the outside of storage liquid container, with connecting pipe through flange and valve and storage liquid container UNICOM, the bottom position of measuring guide can be higher than, be equal to or less than the bottom position of storing liquid container.

3, the instrument of measuring liquid level according to claim 1 and 2 and thing position, it is characterized in that: add a programme-controlled gain control circuit in the circuit of reception echo, form by linear amplification integrated circuit and resistance, electric capacity, a plurality of resistance string are unified into a voltage divider, and different decay is provided by each tap line in the voltage divider.

4, the instrument of measuring liquid level according to claim 1 and 2 and thing position, it is characterized in that described singlechip CPU unit is selected as main control unit, the control survey program is also handled measurement result, measurement result is shown by digital display unit, to surpassing the liquid level of bound, CPU element can be pointed out warning, and adopts wireless or wired the sending in the remote pulpit of serial communication.