CN103454344B - Device and method for simultaneously measuring components and flow of methane - Google Patents
Device and method for simultaneously measuring components and flow of methane Download PDFInfo
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Abstract
The invention relates to a device and a method for simultaneously measuring components and flow of methane. The method comprises the following steps: controlling an output signal of an amplifying circuit through an automatic gain circuit, identifying that whether a gas to be measured is air or methane through judging the relative size of an ultrasonic signal, if the gas to be measured is the methane, measuring the sound velocity of the methane through an ultrasonic sensor, measuring the temperature of the methane through a temperature measuring unit, calculating the volume concentration of CO2 gas in the methane by using a mixed gas characteristic equation, calculating the volume concentration of vapor by using a relation between the temperature and saturated vapor pressure, finally obtaining a volume concentration of CH4 gas, and measuring the flow of the methane through measuring a time difference between fair current and adverse current of the ultrasonic signal. According to the method, through treating signals measured by one temperature sensor and one ultrasonic sensor, the components and the flow of the methane can be measured, and an effective solution is provided for low-cost requirement in methane industrial application.
Description
Technical field
The present invention relates to device and the measuring method of a kind of gas ingredients and flow, especially relate to a kind of device and measuring method of simultaneously measuring biogas composition and flow.
Background technology
In commercial production, Gas Thickness Detecting Technology is widely used in the fields such as chemical industry processing, environmental protection tests and power industry, and the method that detects at present gas concentration has a lot, as chemical analysis, infrared absorption, corona discharge method, supersonic testing method etc.Chemical analysis method should not detect online; Corona discharge sensor life-time is shorter, work that can not be steady in a long-term; Infrared absorption volume complexity is huge, and cost is high, is difficult to promote.With ultrasonic measurement ternary gas concentration have that measurement range is wide, equipment volume is little is easy to realize the features such as online detection.
In commercial production, the flow detection of gas is also an increasingly important index, detect the flowmeter of gas flow also have a variety of, the 17th century evangelista torricelli establish the theoretical foundation of differential pressure flowmeter, this is the milestone of flow measurement.18, the blank of many type instrument of 19th century flow measurement starts to form, as weir, trace method, pitot tube, Venturi tube, volume and turbo flow meter etc.20th century are due to process industrial, energy meter, the demand sharp increase of municipal service to flow measurement, just impel instrument to develop rapidly, developing by leaps and bounds of microelectric technique and computer technology greatly promotes instrument update, and new flowmeter emerges like the mushrooms after rain.So far, it is said that existing hundreds of flowmeter invests market, as hot type, ultrasound wave, selects into vortex etc.And the advantage having with ultrasonic wave principle measurement gas flow is as follows
1. can be used to measure the gas flow and the large-caliber flow that are difficult for contact, are difficult for observation;
2. can not change the flow state of fluid, can not produce the pressure loss, and be convenient to install;
3. can measure the flow of strong corrosive media and non-conductive medium;
4. the volumetric flow rate of measuring is not subject to the impact of the thermal physical property parameters such as pressure, viscosity and the density of tested gas.
In the process control of biogas engineering, relate to the measurement to two of biogas composition and flow important indicators, the variation of methane in sewage gas concentration has great impact to the quality of biogas, the flow measurement of biogas can be reacted production capacity and use amount, so in biogas engineering control procedure, the flow that should monitor biogas is monitored the concentration of methane in sewage gas again, according to the process control of testing result change aerogenesis, so that the methane energy of output reaches the request for utilization of biogas engineering.
Formulate the standard of gas metering according to ISO (ISO (International Standards Organization)), it is the relevant criterion according to AGA (combustion gas association of the U.S.: American Gas Association), and the standard about ultrasonic gas flowmeter amount aspect of mentioning in the up-to-date No. nine Bao Zheng's case in issuing in June, 1998 of AGA, be only authoritative technical manual about in this respect in the world, countries in the world are in practice all using this as foundation.
In AGA report, drum in 2 points:
1. in measurement, pressure can not be lower than 2MPa, and this is that gas density is large because of pressure height, and acoustic impedance is now larger, and receiver media and sensor easily carry out impedance matching, and hyperacoustic like this to transmit and receive signal also strong.
2. measurement gas is as far as possible pure, particularly CO
2content can not be too high, conventionally require to be less than 10%, because CO
2very large to hyperacoustic decay, CO
2when concentration is higher, be unfavorable for very much the reception of signal.
And household biogas pressure is generally less than 10kPpa, joint household biogas pressure is also less than 20kPpa, and CH in the biogas that can light
4concentration can be low to moderate 35%, now CO
2the high energy of concentration reach 65%, the CO that the present invention just can solve in high concentration
2in biogas, measure CH
4concentration.
In patent No. ZL 02800155.9, Teijin Ltd has proposed to utilize the device and method of ultrasonic measuring gas concentration and flow, this invention provides a kind of device of measuring for the oxygen concentration in oxygenerator and flow, and measurement gas is that the binary gas of oxygen and air detects.But, utilize ultrasonic wave principle to biogas composition (saturated steam, CH in biogas engineering
4and CO
2ternary gas) measure, use the method in ZL 02800155.9 to solve.In the patent No. 200510045723.4, Liaoning Project Technology University has proposed to utilize two-phase flow measurement gas concentration measuring apparatus and the method for ultrasound wave and capacitive transducer, also only for measuring binary gas concentration.Zhengzhou GL Tech Company is at patent CN201220509398, CN201220423254, CN201220423320, CN201220421689, CN201220425557, CN201220425558, CN201210374788, methane concentration that many coal mine use and the method and apparatus of flow measurement have been proposed in the patents such as CN201210374786, but can only measure the measurement of concetration of methane in colliery (binary gas that contains methane and air), and in colliery, carbon dioxide content is very low, affect hardly the reception of ultrasonic signal, adopt the patent of Zhengzhou GL Tech Company cannot solve the CO of high concentration
2cH in gas and in saturated aqueous vapor
4the measurement problem of volumetric concentration, more cannot measure high concentration CO
2biogas in gas ingredients.
In above-mentioned mentioned patent, be all to measure for the concentration of identical measurement gas, gas ingredients do not analyzed, more different measuring gas is not judged.
In patent No. EP20070765679, German E+H put forward a kind of utilize ultrasound wave measure simultaneously biogas composition and concentration device and method, this invention utilizes the principle of the ultrasonic measurement velocity of sound to the biogas composition (CH in biogas engineering
4, CO
2, saturated steam) measure, because CH4 concentration in biogas composition can change between 30%～75%, conventionally in biogas CH4 concentration in 60% left and right, and now, the velocity of sound of biogas is just basically identical with air, and therefore, this patent body of cannot district office ventilating be biogas or air.And China is wideling popularize biogas as green energy resource at present, country, to using biogas to carry out subsidizing with gas, therefore must have a kind of method of economy can measure composition and the flow of biogas simultaneously simultaneously, and can reliable district office's ventilation body be biogas or air.Like this, just can avoid the situation of gaining the subsidy of biogas use gas by cheating to occur.
Therefore, in China's biogas engineering, in the time not producing biogas, the gas of device of flowing through is air, this timer can not be charged to flow and the total amount of biogas, so first will judge the gas ingredients of the device of flowing through, the method for mentioning in above-mentioned patent just cannot solve such problem.
Illustrate the problem that gas ingredients is judged that the present invention solves below.
The theoretical following list of deriving of speed that ultrasound wave is propagated in dry biogas and air:
From list, can find out that gas is different with the speed of propagating in air in biogas.At 20 DEG C, the airborne velocity of sound is 343.0164739m/s, 60%CH
4velocity of sound 341.0643366m/s in the biogas of concentration, so at 60%CH
4biogas and air in the speed propagated basically identical, and methane concentration in biogas is all 60% left and right conventionally, at this moment we can by gain control unit control amplifying circuit output signal, unanimously (attenuation degree of ultrasonic signal in gas with various be different from output ultrasonic wave signal magnitude in air, the peak value of the ultrasonic signal of propagating in air and biogas differs greatly), by judging the namely amplifying circuit gain that directly the ultrasonic signal amplitude of output is set divided by gain control unit of relative size of ultrasonic signal, the identification gas of surveying is air or biogas, the relative size of ultrasonic signal amplitude is less than at 0.4 o'clock, the gas of surveying is biogas.
In sum, at present also there are not people or company to utilize ultrasonic wave principle to measure the research of biogas composition and flow aspect simultaneously, an analyser that simply utilizes infrared technique to detect methane in sewage gas concentration, price is generally with Wan Yuanji, and the precession spiral flowmeter price of the measurement gas flow that a Daepori is logical is generally 5,000 yuan of left and right.The carrying out of the signal that the present invention only records by a temperature sensor and a pair of ultrasonic sensor processed and just can complete the measurement to biogas composition and flow, for the low cost in biogas commercial Application requires to provide effective solution.
Summary of the invention
The present invention solves the existing technical matters of prior art; Provide a kind of and can just can complete the measurement to biogas composition and flow by the simple process of signal that a temperature sensor and a pair of ultrasonic sensor are recorded, by the low-cost design of ultrasonic measuring unit, under the requirement that meets precision, reach the object of measurement, for the low cost in biogas commercial Application has required to provide very simply a kind of device and measuring method of measuring biogas composition and flow of solution simultaneously.
Above-mentioned technical matters of the present invention is mainly solved by following technical proposals:
A device of simultaneously measuring biogas composition and flow, is characterized in that, comprising:
One single-chip microcomputer: control driver element and send driving signal, control counter starts counting simultaneously; Receive the peak signal of peak detection unit, by single-chip microcomputer internal signal amplitude closed loop control algorithm, be adjusted the enlargement factor of signal demand, concurrently send the instruction of enlargement factor to gain control unit; The voltage signal that receives temperature sensor, is converted to temperature; Control human-computer interface system.
Two ultrasonic sensors that are arranged in biogas pipeline, i.e. ultrasonic sensor one and ultrasonic sensor two: thereby for transmitting and receiving the velocity of sound and the flow velocity of ultrasonic signal measurement biogas; Wherein, when ultrasonic sensor one is launched ultrasonic signal, ultrasonic sensor two receives the signal that ultrasonic sensor one is launched, and when ultrasonic sensor two is launched ultrasonic signal, ultrasonic sensor one receives the signal that ultrasonic sensor two is launched;
One driver element: be subject to Single-chip Controlling, for driving ultrasonic sensor transmitting ultrasonic signal;
One amplifying circuit: for receiving the ultrasonic signal of ultrasonic sensor one and ultrasonic sensor two and signal being amplified;
One peak detection unit: receive the ultrasonic signal after amplifying circuit amplifies, and send peak signal to single-chip microcomputer;
One gain control unit: receive the instruction of the enlargement factor of single-chip microcomputer transmission, and according to the enlargement factor of this instruction control amplifying circuit.
One comparer: receive the signal after amplifying circuit is adjusted; And stop counting according to the height output output level of signal for control counter;
One counter: Single-chip Controlling is opened counting, comparer output level rising edge control counter stops counting.
One temperature sensor: output voltage varies with temperature, passes to single-chip microcomputer by voltage signal and carries out calculation process, obtains biogas temperature;
One human-computer interface system: receive biogas composition and the flow information of the final output of single-chip microcomputer, and show.
A method of simultaneously measuring biogas composition and flow, is characterized in that, comprises the following steps:
Whether one is detected current surveyed gas is in real time the step of biogas: based on signal amplitude closed loop control algorithm, judge biogas and air according to the relative amplitude of signal, the relative amplitude of described signal be peak detection unit detect peak value detected amplitude divided by enlargement factor, it is biogas that relative amplitude is less than at 0.6 o'clock, and being greater than at 0.6 o'clock is air.
Measure the step of biogas composition for one: carry out the measurement of biogas composition based on binary method, first measure the velocity of sound c of biogas by ultrasonic sensor, measure the temperature of biogas by temperature measurement unit, then calculate CO in biogas based on mixed gas secular equation
2the volumetric concentration of gas
calculated the volumetric concentration of water vapor by the relation of temperature and saturation water air pressure
finally can be calculated CH
4the volumetric concentration of gas
Measure the step of biogas flow for one: the mistiming by measurement ultrasonic signal following current and adverse current records the flow velocity of biogas, thereby calculates the flow of biogas.
In a kind of above-mentioned method of measuring biogas composition and flow simultaneously, wherein the concrete measuring method of the velocity of sound c of biogas is: the path of definition ultrasound wave walking is L, and described path is sound path; Two ultrasonic sensor axis and conduit axis angle are θ: first launched the ultrasonic signal of downbeam by ultrasonic sensor one, received by ultrasonic sensor two, recording the travel-time by counter is t
a; Secondly, launched the ultrasonic signal of countercurrent direction by ultrasonic sensor two, received by ultrasonic sensor one, recording the travel-time by counter is t
b; The velocity of sound of biogas
In a kind of above-mentioned method of measuring biogas composition and flow simultaneously, the step concrete grammar of described measurement biogas composition is:
Step 3.1, the velocity of sound of the biogas of being surveyed by ultrasonic sensor is c, is directly measured the temperature t of surveyed biogas by temperature measurement unit, gets final product to obtain CO
2the volumetric concentration of gas
Step 3.2, is calculated the volumetric concentration of water vapor by the relation of temperature and saturation water air pressure
?
wherein,
P
s=0.0004276201987 × t
4+ 0.02650568145 × t
3+ 1.348945011 × t
2+ 45.38104831 × t+606.36944, wherein t is the biogas temperature that temperature measurement unit records; P is local atmospheric pressure;
Step 3.3, CH in biogas
4the volumetric concentration of gas is
In a kind of above-mentioned method of measuring biogas composition and flow simultaneously, the step concrete grammar of described measurement biogas flow is: the velocity of sound of biogas is c, and the flow velocity of biogas is u; The flow q=∫ udt that can obtain biogas according to the time to the integration of biogas instantaneous velocity, completes the measurement to biogas flow q, wherein, and flow velocity
Therefore, tool of the present invention has the following advantages: can just can complete the measurement to biogas composition and flow by the simple process of signal that a temperature sensor and a pair of ultrasonic sensor are recorded, by the low-cost design of ultrasonic measuring unit, under the requirement that meets precision, reach the object of measurement, for the low cost in biogas commercial Application requires to provide very simple solution.
Brief description of the drawings
Fig. 1 is structural representation of the present invention.
Embodiment
Below by embodiment, and by reference to the accompanying drawings, technical scheme of the present invention is described in further detail.
Embodiment:
Measure a method and apparatus for biogas composition and flow, device comprises human-computer interface system, temperature sensor, single-chip microcomputer, driver element, ultrasonic sensor one, ultrasonic sensor two, amplifying circuit, comparer, counter, peak detection unit and gain control unit simultaneously;
Human-computer interface system in apparatus of the present invention is connected with single-chip microcomputer, single-chip microcomputer is connected with temperature sensor, driver element, counter, peak detection unit and gain control unit respectively, the work of driver element control ultrasonic sensor one and ultrasonic sensor two, the signal output part of ultrasonic sensor one and ultrasonic sensor two is connected with amplifying circuit respectively, gain control unit control amplifying circuit, amplification circuit output end is connected with comparer, peak detection unit respectively, and comparer is connected with counter.
Single-chip microcomputer in the present invention is alternately controlled ultrasonic sensor one and ultrasonic sensor two is launched ultrasonic signal through driver element, when ultrasonic sensor one is launched ultrasonic signal, ultrasonic sensor two receives the signal that ultrasonic sensor one is launched, when ultrasonic sensor two is launched ultrasonic signal, ultrasonic sensor one receives the signal that ultrasonic sensor two is launched, in driver element control ultrasonic sensor transmitting ultrasonic signal, open rolling counters forward, another ultrasonic sensor receives ultrasonic signal after amplifying circuit simultaneously, send peak detection unit to, peak detection unit sends the peak signal detecting to single-chip microcomputer, single-chip microcomputer is after relatively calculating, draw a rational enlargement factor, then send instruction to gain control unit, gain control unit control amplifying circuit is adjusted ultrasound wave peak signal size, make the size of signal substantially keep certain amplitude, signal after treatment sends comparer to, comparer is in the time that signal reaches threshold level generation upset, control counter stops counting (in the present embodiment, in signal output low level during lower than 0.92V, during higher than 1.25V, export high level, output level stops counting for control counter, stop counting at comparer output level rising edge (rising edge is exactly the process that low level changes to high level) control counter, 0.92V and 1.25V refer to the voltage of input, 0V and 3.3V when the level of output), and send count value now to single-chip microcomputer and carry out calculation process, simultaneous temperature sensor is directly measured tested biogas temperature, biogas temperature signal is passed to single-chip microcomputer and carry out calculation process, after the complete all signals that receive of single-chip microcomputer calculation process, export the composition of required biogas and flow information to human-computer interface system.
A method and apparatus of simultaneously measuring biogas composition and flow, method comprises the following steps:
(1) consistent with output ultrasonic wave signal magnitude in air by gain control unit control amplifying circuit output ultrasonic wave signal, relative size by judging ultrasonic signal namely amplifying circuit directly the ultrasonic signal amplitude of output divided by gain control unit control amplifying circuit output ultrasonic wave signal amplitude, the identification gas of surveying is air or biogas, the relative amplitude of ultrasonic signal is less than at 0.4 o'clock, and the gas of surveying is biogas; (general, the relative amplitude of ultrasonic signal is 1 o'clock, and gas is air, and amplitude is less than at 0.2 o'clock relatively, gas is biogas, considers error, and it is biogas that signal is less than at 0.6 o'clock, and being greater than at 0.6 o'clock is air, in the present embodiment, be decided to be and be less than 0.4, the gas of surveying is biogas)
The relation (taking ultrasound wave air chamber caliber DN32mm as example) of ultrasonic signal amplitude and CH4 concentration
| CH4 concentration % | CO2 concentration % | Amplitude V | Actual gain | Amplitude relatively |
| AIR | 0 | 3 | 3.68 | 100.00% |
| 100 | 0 | 1.44 | 12.972 | 13.62% |
| 90 | 10 | 1.41 | 13.887 | 12.45% |
| 80 | 20 | 1.34 | 15.23 | 10.79% |
| 70 | 30 | 1.3 | 16.86 | 9.46% |
| 60 | 40 | 1.26 | 20.346 | 7.60% |
| 50 | 50 | 1.2 | 24.84 | 5.93% |
| 40 | 60 | 0.83 | 30.64 | 3.33% |
| 30 | 70 | 0.55 | 38 | 1.78% |
(2) if the gas of surveying is biogas, first measure the velocity of sound of biogas by ultrasonic sensor, measure the temperature of biogas by temperature measurement unit, then calculate the volumetric concentration of CO2 gas in biogas by mixed gas secular equation
calculated the volumetric concentration of water vapor by the relation of temperature and saturation water air pressure
finally can be calculated the volumetric concentration of CH4 gas
(3) record the flow velocity of biogas by the mistiming of measuring ultrasonic signal following current and adverse current simultaneously, thereby calculate the flow of biogas.
The ultrasonic signal direction of propagation is consistent with airflow direction is following current transmission, and as shown in Figure 1, ultrasonic sensor two transmits, and it is following current transmission that ultrasonic sensor one receives signal;
The ultrasonic signal direction of propagation and airflow direction are adverse current transmission on the contrary, and as shown in Figure 1, ultrasonic sensor one transmits, and it is adverse current transmission that ultrasonic sensor two receives signal.
The measuring method of biogas composition and flow comprises the following steps:
Measure the velocity of sound and the flow velocity of the biogas of surveying;
If when ultrasound wave is propagated in biogas, the transmission time of downbeam is ta, and the transmission time of countercurrent direction is tb, and the velocity of sound of biogas is c, and the flow velocity of biogas is u, and ultrasonic measurement distance L is definite value, and ultrasonic sensor axis and conduit axis angle are θ,
The transmission time ta=Lcos θ of downbeam/(c+u);
The transmission time tb=Lcos θ of countercurrent direction/(c-u);
Carrying out simple calculations processing can obtain:
Time that ultrasound wave is propagated in biogas and be (tb+ta)=2Lccos θ/(c2-u2);
The mistiming that ultrasound wave is propagated in biogas is (tb-ta)=2Lucos θ/(c2-u2);
The speed of propagating in biogas much smaller than ultrasound wave due to the flow velocity of biogas self, c value is much larger than u value, (c2-u2) approximate think c2 can obtain after simplification:
The time of transmitting in biogas according to ultrasound wave and formula can obtain the velocity of sound c=2Lcos θ of biogas/(ta+tb),
The mistiming formula transmitting in biogas according to ultrasound wave can obtain flow velocity u=0.5c2 (the tb-ta)/Lcos θ of biogas
Measure the temperature t of the biogas of surveying
Directly measured the temperature t of surveyed biogas by temperature measurement unit, the kelvin degree of the biogas of surveying is T=t+273, and this temperature signal sends single-chip microcomputer to and calculates, and can obtain the volumetric concentration of CO2 gas in biogas
Biogas is the three-element mixed gas body of methane, carbon dioxide and saturated steam, has recorded the velocity of sound of biogas, and the temperature of biogas, then calculates the volumetric concentration of CO2 gas in biogas by mixed gas secular equation
its computing method are as follows:
A. for the biogas that contains methane, carbon dioxide and three kinds of gases of saturated steam,
c by the velocity of sound of survey biogas,
for biogas mean specific heat ratio, R is universal gas constant, and T is kelvin degree,
for the mean molecular weight of biogas; Wherein:
for the specific heat at constant volume of saturated steam,
for the specific heat at constant volume of methane,
for the specific heat at constant volume of carbon dioxide,
for the specific heat at constant pressure of saturated steam,
for the specific heat at constant pressure of methane,
for the specific heat at constant pressure of carbon dioxide,
R=8.3145，T=t+273；
B. by
?
C. after fortran and obtain the volumetric concentration computing formula of CO2 gas:
D. the physical characteristic data of looking into three kinds of combination gass in biogas obtains: Cv H2O=2.474, and Cp H2O=1.860,
cvCH4=2.839, CpCH4=2.189,
cvCO2=1.078, CpCO2=0.829,
E. be simplified operation, when actual computation, order
the impact of the error that assessment is introduced thus on methane concentration:
For the biogas that contains saturated steam, order
the extreme case of deviation maximum is: saturated steam n1=10% is-20 DEG C～40 DEG C according to the operating temperature range of instrument, and the maximum level of aqueous vapor is 40 DEG C
cH4 volumetric concentration
cO2 volumetric concentration
substitution
?
so in actual biogas
Order
after calculating, draw by
the maximum cause error of introducing is less than 0.45%, so by
the fiducial error of introducing is negligible, so the volumetric concentration computing formula of CO2 gas can be reduced to:
F. be simplified operation, when actual computation, water vapor maximum volume concentration is 7.28%, so the error of the volumetric concentration of the CO2 gas of being introduced by water vapor is 0.5% can ignore, gets final product to obtain the volumetric concentration of CO2 gas
G. obtain kelvin degree T and the velocity of sound c of the biogas of surveying, can draw the volumetric concentration value of CO2 gas in biogas
Calculated the volumetric concentration of water vapor by the relation of temperature and saturation water air pressure
Within the scope of-20 DEG C～50 DEG C, the relational expression of saturation water air pressure Ps and temperature t is:
Ps=0.0004276201987*t4+0.02650568145*t3+1.348945011*t2+45.38104831*t1+606.36944
Recorded the temperature t of biogas by temperature measurement unit, can calculate saturation water air pressure Ps by relational expression, by formula
calculate vapor content percent by volume
wherein P is local atmospheric pressure, is made as 101.325kPa;
Obtain the volumetric concentration value of CO2 gas in biogas
volumetric concentration with saturated steam
the volumetric concentration that can calculate CH4 gas in biogas is
Adopt the mistiming of measurement ultrasound wave following current and adverse current to record the flow of biogas, its method is as follows:
Adopt the mistiming principle that ultrasound wave transmits in biogas can record the flow velocity u of biogas, be designated as q thereby calculate biogas flow;
Obtained the flow velocity u of the biogas of surveying by step (1), can obtain the flow q=∫ udt of biogas according to the time to the integration of biogas instantaneous velocity, completed the measurement to biogas flow q.
Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendments or supplement or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.
Claims (1)
1. a method of simultaneously measuring biogas composition and flow, is characterized in that, adopts following device to measure:
One single-chip microcomputer: control driver element and send driving signal, control counter starts counting simultaneously; Receive the peak signal of peak detection unit, by single-chip microcomputer internal signal amplitude closed loop control algorithm, be adjusted the enlargement factor of signal demand, concurrently send the instruction of enlargement factor to gain control unit; The voltage signal that receives temperature sensor, is converted to temperature; Control human-computer interface system;
Two ultrasonic sensors that are arranged in biogas pipeline, i.e. ultrasonic sensor one and ultrasonic sensor two: thereby for transmitting and receiving the velocity of sound and the flow velocity of ultrasonic signal measurement biogas; Wherein, when ultrasonic sensor one is launched ultrasonic signal, ultrasonic sensor two receives the signal that ultrasonic sensor one is launched, and when ultrasonic sensor two is launched ultrasonic signal, ultrasonic sensor one receives the signal that ultrasonic sensor two is launched;
One driver element: be subject to Single-chip Controlling, for driving ultrasonic sensor transmitting ultrasonic signal;
One amplifying circuit: for receiving the ultrasonic signal of ultrasonic sensor one and ultrasonic sensor two and signal being amplified;
One peak detection unit: receive the ultrasonic signal after amplifying circuit amplifies, and send peak signal to single-chip microcomputer;
One gain control unit: receive the instruction of the enlargement factor of single-chip microcomputer transmission, and according to the enlargement factor of this instruction control amplifying circuit;
One comparer: receive the signal after amplifying circuit is adjusted; And stop counting according to the height output output level of signal for control counter;
One counter: Single-chip Controlling is opened counting, comparer output level rising edge control counter stops counting;
One temperature sensor: output voltage varies with temperature, passes to single-chip microcomputer by voltage signal and carries out calculation process, obtains biogas temperature;
One human-computer interface system: receive biogas composition and the flow information of the final output of single-chip microcomputer, and show;
The method comprises the following steps:
Whether one is detected current surveyed gas is in real time the step of biogas: based on signal amplitude closed loop control algorithm, judge biogas and air according to the relative amplitude of signal, the relative amplitude of described signal be peak detection unit detect peak value detected amplitude divided by enlargement factor;
Measure the step of biogas composition for one: carry out the measurement of biogas composition based on binary method, first measure the velocity of sound c of biogas by ultrasonic sensor, by the temperature of temperature sensor measurement biogas, then calculate CO in biogas based on mixed gas secular equation
2the volumetric concentration of gas
calculated the volumetric concentration of water vapor by the relation of temperature and saturation water air pressure
finally can be calculated CH
4the volumetric concentration of gas
Measure the step of biogas flow for one: the mistiming by measurement ultrasonic signal following current and adverse current records the flow velocity of biogas, thereby calculates the flow of biogas;
Wherein the concrete measuring method of the velocity of sound c of biogas is: the path of definition ultrasound wave walking is L, and described path is sound path; Two ultrasonic sensor axis and conduit axis angle are θ: first launched the ultrasonic signal of downbeam by ultrasonic sensor one, received by ultrasonic sensor two, recording the travel-time by counter is t
a; Secondly, launched the ultrasonic signal of countercurrent direction by ultrasonic sensor two, received by ultrasonic sensor one, recording the travel-time by counter is t
b; The velocity of sound of biogas
The step concrete grammar of described measurement biogas composition is:
Step 3.1, the velocity of sound of the biogas of being surveyed by ultrasonic sensor is c, is directly measured the temperature t of surveyed biogas by temperature sensor, gets final product to obtain CO
2the volumetric concentration of gas
Step 3.2, is calculated the volumetric concentration of water vapor by the relation of temperature and saturation water air pressure
?
wherein,
P
s=0.0004276201987 × t
4+ 0.02650568145 × t
3+ 1.348945011 × t
2+ 45.38104831 × t+606.36944, wherein
tit is the biogas temperature that temperature sensor records; P is local atmospheric pressure;
Step 3.3, in biogas, the volumetric concentration of CH4 gas is
The step concrete grammar of described measurement biogas flow is: the velocity of sound of biogas is c, and the flow velocity of biogas is u; The flow q=∫ udt that can obtain biogas according to the time to the integration of biogas instantaneous velocity, completes the measurement to biogas flow q, wherein, and flow velocity
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| CN103900651B (en) * | 2014-04-09 | 2016-06-22 | 浙江威星智能仪表股份有限公司 | A kind of ultrasonic wave gas meter mixed signal processes circuit |
| JP6379069B2 (en) | 2015-04-09 | 2018-08-22 | 東京瓦斯株式会社 | Calorific value derivation device and calorific value derivation method |
| CN109708729B (en) * | 2018-12-14 | 2020-10-20 | 金卡智能集团股份有限公司 | Automatic gain adjustment method for metering signal of ultrasonic meter and ultrasonic gas meter |
| DE102022107386A1 (en) | 2022-03-29 | 2023-10-05 | Marquardt Gmbh | Flow sensor for determining a flow rate of a fluid flowing along a flow direction |
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