CN2204419Y - Intelligent instrument for measuring and controlling concentration of acid, alkali and salt - Google Patents
Intelligent instrument for measuring and controlling concentration of acid, alkali and salt Download PDFInfo
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- CN2204419Y CN2204419Y CN 94213375 CN94213375U CN2204419Y CN 2204419 Y CN2204419 Y CN 2204419Y CN 94213375 CN94213375 CN 94213375 CN 94213375 U CN94213375 U CN 94213375U CN 2204419 Y CN2204419 Y CN 2204419Y
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Abstract
The utility model discloses an intelligent instrument for measuring and controlling concentration of acid, alkali and salt, comprising a four-electrode transmitter, a conductance measuring unit, a temperature measuring unit and a singlechip system. The utility model is characterized in that the conductance measuring unit uses the design project of an electrode current closed-loop regulation, the temperature measuring unit which is composed of a thermal resistance, an unbalanced bridge and an amplification output unit is added, and the singlechip is used to do nonlinear correction and temperature compensation. The utility model has the advantages of reasonable structure design, low cost and measurement precision and stability of the measurer increase, being widely used for automatically measuring and controlling concentration of various acid, alkali and salt.
Description
The utility model relates to a kind ofly measures the instrument of solution acid alkali salt concentration by measuring conductivity, exactly is a kind of intelligent soda acid salinity measuring and controlling instrument.
The method of measuring detected solution acid, alkali, salinity by the conductivity of measuring solution is one of method commonly used in the commercial production, can adopt two electrode methods or four electrode method to measure usually, the trip temperature of going forward side by side compensation.The measurement instrument based on above-mentioned principle that prior art provides (for example DD-5A acid base concentration meter) adopts two electrode methods, and precision and degree of stability all have much room for improvement.Existing conductance measurement unit adopts the self balancing circuit structure of current feedback, occurs self-sustained oscillation easily; Temperature-sensing element in parallel in the input signal circuit is adopted in its temperature compensation, and compensating error is big, and scope is little, is difficult for regulating.
The purpose of this utility model is to utilize four electrode structures and microcomputer technology, designs a kind of intelligent soda acid salinity measuring and controlling instrument, to overcome above-mentioned weak point.
The utility model comprises panel, frame, casing, power supply, terminal strip, display, operating key, host computer system plate and measuring unit plate, it is characterized in that on the said measuring unit plate conductance measurement and temperature measurement unit being installed, said conductance measurement unit comprises four electrode transmitters, amplifying unit, rectification unit, comparing unit, pi element, modulation amplifying unit, square-wave generator, output unit and reference power supply, and the voltage electrode of electrode transmitter is through input resistance R
1, R
2Link with two input ends of amplifying unit, the output terminal of amplifying unit and the input end of rectification unit link, an input end of the output terminal of rectification unit and comparing unit links, another input end of reference power supply and comparing unit links, the output terminal of comparing unit and the input end of pi element link, the output terminal of pi element links with the input end of modulation amplifying unit, the output terminal of square-wave generator also links with the input end of modulating amplifying unit through triode G, the output terminal of modulation amplifying unit and a voltage electrode of four electrode transmitters link, another voltage electrode of four electrode transmitters and the input end of output unit link, the d. c. voltage signal V that the output terminal of output unit will be directly proportional with the detected solution conductivity
θ 1Send into the host computer system plate, said temperature measurement unit comprises thermal resistance, unbalanced bridge and amplification output unit, thermal resistance is connected on the arm of unbalanced bridge, two output terminals of imbalance electricity emigrant link with two input ends that amplify output unit respectively, and the output terminal that amplifies output unit will be by the next d. c. voltage signal V of dut temperature conversion of signals
θ 2Send into the host computer system plate, said motherboard adopts can be to d. c. voltage signal V
θ 1Corresponding detected solution concentration is carried out non-linear correction and can be to d. c. voltage signal V
θ 2The Single Chip Microcomputer (SCM) system plate that detected solution concentration under the corresponding temperature is carried out temperature compensation.
The utility model is owing to adopted four electrodes and electrode current closed loop regulation circuit structure, adopt single-chip microcomputer to carry out nonlinear concentration correction and temperature self-compensation simultaneously, improved the measuring accuracy and the stability of instrument, the precision of instrument is 1%, sensitivity can reach 0.05%, and stability is 0.5%.
The utility model has following accompanying drawing:
Fig. 1 the utility model structural representation
Fig. 2 the utility model principle of work block diagram
Fig. 3 measuring unit structured flowchart
Fig. 4 conductance measurement element circuit structural representation
Fig. 5 temperature measurement unit electrical block diagram
Fig. 6 the utility model main program block diagram
Fig. 7 temperature compensation, non-linear revision program block diagram
Below in conjunction with accompanying drawing the utility model is elaborated.
Fig. 1 is the utility model structural representation, comprises panel 28, frame 29, casing 30, power supply 35, terminal strip 36, display 19, operating key 20, host computer system plate 39 and measuring unit plate 40.Conductance measurement unit and temperature measurement unit 15 are installed on the measuring unit plate 40, also claim analog circuit board.The conductance measurement unit comprises four electrode transmitters 1, amplifying unit 2, rectification unit 3, comparing unit 4, pi element 6, modulation amplifying unit 7, square-wave generator 8, output unit 9 and reference power supply 5, and its particular circuit configurations can be referring to Fig. 3, Fig. 4.
The utility model adopts the design proposal of electrode current closed loop adjustment, can realize that the steady and continuous of electrode current is regulated.Voltage signal on the voltage electrode 32,33 is earlier through amplifying rectification, again with reference voltage V
BCompare, its difference is after amplifying, again through pi element, export a conditioning signal that concerns with the difference proportional integral, this signal is modulated into the ac square wave signal through modulating unit, is added on the galvanic electrode 31,34 after amplifying, and realizes the closed loop adjustment of electric current with this.The concrete course of work of conductance measurement unit is as follows:
The four electrode transmitters 1 of measuring electrical conductivity of solution insert in the detected solution, and wherein 31,34 liang of electrodes are galvanic electrode, and 32,33 electrodes are voltage electrode.When instrumentation, galvanic electrode is at impressed voltage V
1.4Effect under, flow through an electric current I
LThis electric current produces a voltage drop V on voltage electrode
2.3, this voltage is an only small square wave voltage signal of several millivolts.Voltage V
2.3 pass through input resistance R
1, R
2, be connected on two input ends of differential motion amplifying unit 2, through amplifying and a direct current voltage V is exported in full-wave rectification unit 3 at the two poles of the earth
A, this voltage is received an input end of comparing unit 4, another reference voltage V
BBe connected on another input end of comparing unit.Work as V
AEqual V
BThe time, amplifier is output as zero, works as V
ABe not equal to V
BVoltage △ V of time output
AB, this voltage is regulated the voltage V that is added on the galvanic electrode 31,34 through pi element 6 and modulation amplifying unit 7
14, make the electric current I that flows through solution
LChange, thereby change V
1.3Voltage makes the V after the amplification
AVoltage and V
BBe tending towards equal, work as V
A≈ V
BThe time, system is in equilibrium state, I
LRemain unchanged.When the conductivity of solution changes, I
LChange V
2.3And V
AChange thereupon, cause system's imbalance.By automatic adjusting electric current I
L, make V
2.3And V
ABe returned to original value, system has reached new balance.I after stable
LValue is to be directly proportional with the conductivity of solution.Get the pressure drop that this electric current produces and be converted to the d. c. voltage signal V that is directly proportional with conductivity through output unit 9 on resistance
θ 1, send into Single Chip Microcomputer (SCM) system.
Temperature measurement unit of the present utility model comprises thermal resistance 10, unbalanced bridge 11 and amplifies output unit 12(referring to Fig. 3), particular circuit configurations can be referring to Fig. 5, and it becomes unified d. c. voltage signal V with the dut temperature conversion of signals
θ 2Send into Single Chip Microcomputer (SCM) system.
The conductivity of various acid, alkali, salt, solution can change along with variation of temperature under the constant situation of concentration, and its temperature coefficient is relevant with the kind and the concentration range of solution.For eliminating the influence of temperature variation to concentration measurement, this instrument utilizes single-chip microcomputer to carry out the temperature self-compensation computing.The analog measuring circuit of instrument, conductivity and temperature signal with solution are converted to unified d. c. voltage signal, send into single-chip microcomputer, and single-chip microcomputer compensates computing by certain computing formula and method, calculates the conductivity value under the standard temperature.Temperature compensation coefficient can be set arbitrarily by keyboard 20 according to the actual conditions of detected solution.With a kind of solution, can set more than one temperature compensation coefficient in the variable concentrations scope.
Exist nonlinear relationship between the conductivity of solution and the concentration, must carry out non-linear correction.This instrument also realizes non-linear correction by single-chip microcomputer.It is that nonlinear relationship curve with concentration and conductivity approaches with a second order relational expression that instrument adopts 3 revised laws, its ultimate principle:
Be V
(Y)=C
θ+ (C
1Y)/(C+C
2Y)
The conductivity of Y-solution
V
(Y)The concentration of-solution
C
θ, C
1, C
2-coefficient
The concrete practice is according to concentration known and conductivity relation curve, to ask for C in the formula with three point method
θ, C
1, C
2Three coefficients deposit three coefficients in the computing machine in, and computing machine calculates corresponding concentration value according to the survey conductivity value with above-mentioned formula.This method is easier, and formula is simple, and committed memory is little, and revises the precision height, is applicable to intelligence instrument.
The imput output circuit of host computer system plate 39 can adopt digital to analog converter 16, electricity is led d. c. voltage signal with temperature, be converted to 11 position digital signals, through photoisolator 17, send into Single Chip Microcomputer (SCM) system 18, single-chip microcomputer is sent 8 site concentration signals and conditioning signal into digital to analog converter 21,22, is converted to dc current signal.Single-chip microcomputer also is converted to the switching value output signal with the bound alerting signal by switching value output unit 25.
The flow chart of temperature compensation, non-linear correction is referring to Fig. 7.
Two group of 4 figure place sign indicating number display 19 and 16 operating keys 20 are arranged on the panel 28 of this instrument, link by keyboard and display interface circuit and single-chip microcomputer.Display 19 can switch display density value, electric conductivity value, temperature value, various setup parameter and analog quantity output valve.Utilize 16 bit manipulation keys can import various parameter values and operation signal, operation such as can show switching, parameter setting, self check, man-auto switching, manual operation, reset.The parameter that can set has: the set-point of regulator, bound alarming value, temperature compensation coefficient, non-linear correction factor, PID setting parameter etc.
This instrument power adopts Switching Power Supply 27, volume is little, good stability, reliable, being applicable to can instrument.
The technical feature that the utility model reached is as follows:
1. measurement of concetration scope: NaOH 0～5%, 0～10%;
H
2SO
40～5％ 0～10％，0～15％；
HCl 0～5％ 0～10％；
NaCl 0～10％ 0～20％；
HNO
30～5％ 0～10％。
2. temperature measurement range: 0～100 ℃.
3. measuring accuracy :≤1% full scale.
4. temperature compensation range: 0～80 ℃, 25 ℃ of reference temperatures.
5. sensitivity: 0.1% full scale, stability: 0.5%
6. band PID regulates automatically.
7. export two groups of 4～20mA DC().
8. the output alarm contact is three groups, capacity 24V 3A.
Claims (1)
1, intelligent acid, alkali, salt, the measurement of concetration controller, comprise: panel (28), frame (29), casing (30), power supply (35), terminal strip (36), display (19), operating key (20), host computer system plate (39), with measuring unit plate (40), it is characterized in that being equipped with on the said measuring unit plate (40) conductance measurement and temperature measurement unit (15), said conductance measurement unit comprises four electrode transmitters (1), amplifying unit (2), rectification unit (3), comparing unit (4), pi element (6), modulation amplifying unit (7), square-wave generator (8), output unit (9) and reference power supply (5), the voltage electrode (32 of electrode transmitter, 33) through input resistance R
1, R
2Link with two input ends of amplifying unit (2), the input end of the output terminal of amplifying unit (2) and rectification unit (3) links, an input end of the output terminal of rectification unit (3) and comparing unit (4) links, reference power supply (5) links with another input end of comparing unit (4), the input end of the output terminal of comparing unit (4) and pi element (6) links, the output terminal of pi element (6) links with the input end of modulation amplifying unit (7), the output terminal of square-wave generator (8) also links with the input end of modulating amplifying unit (7) through triode G, the output terminal of modulation amplifying unit (7) and a voltage electrode (31) of four electrode transmitters link, another voltage electrode (34) of four electrode transmitters links the d. c. voltage signal V that the output terminal of output unit (9) will be directly proportional with the detected solution conductivity with the input end of output unit (9)
1Send into host computer system plate (39), said temperature measurement unit comprises thermal resistance (10), unbalanced bridge (11) and amplifies output unit (12), thermal resistance (10) is connected on the arm of unbalanced bridge (11), two output terminals of unbalanced bridge (11) link with two input ends that amplify output unit (12) respectively, and the output terminal that amplifies output unit (12) will be by the next d. c. voltage signal V of dut temperature conversion of signals
2Send into host computer system plate (39), said motherboard (39) adopts can be to d. c. voltage signal V
1Corresponding detected solution concentration is carried out non-linear correction and can be to d. c. voltage signal V
2The Single Chip Microcomputer (SCM) system plate that detected solution concentration under the corresponding temperature is carried out temperature compensation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94213375 CN2204419Y (en) | 1994-06-08 | 1994-06-08 | Intelligent instrument for measuring and controlling concentration of acid, alkali and salt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94213375 CN2204419Y (en) | 1994-06-08 | 1994-06-08 | Intelligent instrument for measuring and controlling concentration of acid, alkali and salt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2204419Y true CN2204419Y (en) | 1995-08-02 |
Family
ID=33829951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 94213375 Expired - Fee Related CN2204419Y (en) | 1994-06-08 | 1994-06-08 | Intelligent instrument for measuring and controlling concentration of acid, alkali and salt |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2204419Y (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101031800B (en) * | 2004-09-30 | 2011-01-05 | 爱科来株式会社 | Analyzer |
| CN102116756A (en) * | 2009-12-30 | 2011-07-06 | 上海城投原水有限公司 | Single chip microcomputer-based liquid electrical conductivity measurement method |
| CN101393154B (en) * | 2008-10-31 | 2012-03-28 | 华南理工大学 | Micro sugar detection device and method thereof |
| CN101398405B (en) * | 2008-11-04 | 2012-07-25 | 中国农业大学 | Water electric conductivity intelligent sensor |
| CN103205769A (en) * | 2012-01-13 | 2013-07-17 | 宝山钢铁股份有限公司 | An acid concentration controlling method for a continuous annealing furnace |
| CN104662413A (en) * | 2012-04-13 | 2015-05-27 | 菲利浦66公司 | A system and method for monitoring ammonium bisulfide |
-
1994
- 1994-06-08 CN CN 94213375 patent/CN2204419Y/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101031800B (en) * | 2004-09-30 | 2011-01-05 | 爱科来株式会社 | Analyzer |
| US8003049B2 (en) | 2004-09-30 | 2011-08-23 | Arkray, Inc. | Analyzer |
| CN101393154B (en) * | 2008-10-31 | 2012-03-28 | 华南理工大学 | Micro sugar detection device and method thereof |
| CN101398405B (en) * | 2008-11-04 | 2012-07-25 | 中国农业大学 | Water electric conductivity intelligent sensor |
| CN102116756A (en) * | 2009-12-30 | 2011-07-06 | 上海城投原水有限公司 | Single chip microcomputer-based liquid electrical conductivity measurement method |
| CN102116756B (en) * | 2009-12-30 | 2014-11-05 | 上海城投原水有限公司 | Single chip microcomputer-based liquid electrical conductivity measurement method |
| CN103205769A (en) * | 2012-01-13 | 2013-07-17 | 宝山钢铁股份有限公司 | An acid concentration controlling method for a continuous annealing furnace |
| CN104662413A (en) * | 2012-04-13 | 2015-05-27 | 菲利浦66公司 | A system and method for monitoring ammonium bisulfide |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |