CN102288645B - Rice field methane concentration sensor - Google Patents
Rice field methane concentration sensor Download PDFInfo
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- CN102288645B CN102288645B CN 201110200030 CN201110200030A CN102288645B CN 102288645 B CN102288645 B CN 102288645B CN 201110200030 CN201110200030 CN 201110200030 CN 201110200030 A CN201110200030 A CN 201110200030A CN 102288645 B CN102288645 B CN 102288645B
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- methane concentration
- concentration sensor
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Abstract
The invention discloses a rice field methane concentration sensor, which comprises a methane probe, a temperature probe, an actuating signal source, a conditioning circuit and a sensor interface, wherein the actuating signal source is connected with the methane probe and the temperature probe respectively; the conditioning circuit is connected with the methane probe, the temperature probe and the sensor interface respectively; the methane probe and the temperature probe are driven by the actuating signal source; after a driving response signal is filtered and amplified by the conditioning circuit, an output voltage Vm of the methane probe, an output voltage Vt of the temperature probe, and a voltage Vd and a null voltage V0 of the actuating signal source are generated; and the voltages Vm, Vt, Vd and V0 are output to the sensor interface. The rice field methane concentration sensor has a simple structure and low cost, and is easy and convenient to operate.
Description
Technical field
The present invention relates to the field information acquisition field, particularly a kind of paddy methane concentration sensor based on the hot wire type gas sensor.
Background technology
Human activities such as burning along with process of industrialization acceleration, population growth, the utilization of irrational soil, large-area deforestation, a large amount of mineral fuel are constantly risen greenhouse gases such as discharge capacitys such as carbon dioxide, methane.The greenhouse effect that greenhouse gases cause, the serious consequence of many threat human survivals such as will to cause that extreme climate generation, The grain yield drops, the ecosystem change, water resource more is becoming tight scarce, forest fire and development.
Methane is the important greenhouse gases that are only second to carbon dioxide, and research shows that methane has the greenhouse effect stronger than carbon dioxide, and the radiation intensity of unit mole of methane is 21 times of carbon dioxide.Although 0.5% of the not enough carbon dioxide of methane concentration can reach 1/3 of carbon dioxide to the contribution of greenhouse effect, can reach more than 15% the contribution of global warming.
The rice field is one of most important emission source of methane, is the important factor in order that the air sphere methane concentration continues rising.It is to adopt the method for static chamber-gas chromatograph that paddy methane concentration detects the most frequently used method.This method uses the chest at a no end to cover institute's geodetic table, extracts air sample in the case with needle tubing at set intervals, measures its methane concentration by gas chromatograph at last.The weak point of this method is, equipment price is expensive, measuring process receives environmental perturbation and manual operation etc. to influence, observe personnel's workload big etc. easily.
The Chinese invention patent application that disclosed publication number was CN1063362A on August 5th, 1992 discloses a kind of paddy methane and has gathered automatically and analytic system; Comprise circuit kit and air-path control system in this scheme; Be mainly used in the automatic collection of gas in the static chamber; Its analytic system still is a gas chromatograph, but is difficult to satisfy requirements such as quick, the convenient and low cost of modern rice field information acquisition.
Based on the research that under paddy environment, is not applied as yet at present of the sensing methane concentration device of gas sensor; Reason is that paddy methane concentration is very low, and gas sensor response is little, and influenced by extraneous factor such as temperature; Signal to noise ratio (S/N ratio) is lower, and measuring accuracy and stability all are difficult to guarantee.
Summary of the invention
To the deficiency of above-mentioned existing paddy methane concentration detection technique, the purpose of this invention is to provide a kind of simple in structure, easy and simple to handle and lower-cost paddy methane concentration sensor.
The present invention adopts following technical scheme to realize above-mentioned purpose: this paddy methane concentration sensor; Comprise methane probe, temp probe, exciting signal source, modulate circuit and sensor interface; Exciting signal source is connected with temp probe with the methane probe respectively, and modulate circuit is connected with methane probe, temp probe and sensor interface respectively; Methane probe and temp probe are driven by exciting signal source, and the response signal of driving produces the output voltage V of methane probe after modulate circuit filtering, processing and amplifying
m, temp probe output voltage V
t, exciting signal source voltage V
dAnd total null voltage V
0Said voltage V
m, V
t, V
dAnd V
0Together export sensor interface to.
Said methane probe is the hot wire type gas sensor, and the hot wire type gas sensor is made up of sensitive resistance and compensating resistance, and wherein compensating resistance and sensitive resistance have the same datum resistance.The sensitive material of said sensitive resistance is a tin ash.
Above-mentioned paddy methane concentration sensor also comprises interconnective data acquisition module and host computer; Sensor interface passes through cable with said voltage V
m, V
t, V
dAnd V
0Be sent to data acquisition module and carry out A/D conversion, transformation result is sent to host computer and preserves and show.
Said data acquisition module is provided with and is no less than 4 data acquisition channels that are connected with sensor interface, and is provided with COM or the USB port that is connected with host computer.
Said modulate circuit comprises low-frequency filter circuit and the amplifying circuit that is connected.Said low-frequency filter circuit is the RC circuit.
Compared with prior art, the present invention has following advantage:
1, sensor is installed in the static chamber inner tip, and static chamber is provided with thermometer socket and air sampling mouth, obtains the methane concentration in the static chamber by gas chromatograph, can demarcate sensor measurement.
2, sensor construction of the present invention is simple, easy and simple to handle, with low cost and reliable and stable.
Description of drawings
Fig. 1 is a paddy methane concentration sensor structural drawing of the present invention;
Wherein: 1, sensor outer housing; 2, accurate exciting signal source; 3, hot wire type methane probe; 4, temp probe; 5, modulate circuit; 6, sensor interface; 7, cable; 8, data acquisition module; 9, host computer.
Fig. 2 is a paddy methane concentration sensor instrumentation plan of the present invention;
Wherein: 10, static chamber; 11, electric fan; 12, thermometer socket and thermometer; 13, air sampling mouth and ST.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the present invention done further describing, but embodiment of the present invention is not limited thereto.
The present invention is from following problem: problem 1, agricultural product home environment information cognition technology and equipment, national 863 major projects, 2011AA100704,2011-2013; Problem 2, the obtaining fast and analysis research of paddy rice-paddy environment system important information, NSFC-Guangdong associating fund, U0931001,2010-2013.
Paddy methane concentration sensor of the present invention is as shown in Figure 1; Comprise sensor outer housing 1; Place methane probe 3, temp probe 4, accurate exciting signal source 2, modulate circuit 5 and the sensor interface 6 of shell 1 inside; Exciting signal source 2 is connected with temp probe 4 with methane probe 3 respectively, and modulate circuit 5 pops one's head in 3 with methane respectively, temp probe 4 is connected with sensor interface 6.Methane probe 3 is driven by accurate exciting signal source 2 with temp probe 4, and the response signal of driving produces 4 road output voltages after modulate circuit 5 filtering, processing and amplifying, be respectively the output voltage V of methane probe 3
m, temp probe 4 output voltage V
t, accurate exciting signal source 2 voltage V
dAnd total null voltage V
0, 4 road output voltages carry out A/D conversion by behind sensor interface 6, being connected to data acquisition module 8 by cable 7, are sent to host computer 9 by COM or USB port then and preserve and show.Wherein the methane probe is exported V
mBy V
t, V
dAnd V
0Carry out zero correction and temperature correction: zero correction is used to eliminate the influence of cable transmission loss; Temperature correction is used to eliminate the influence of environment temperature to methane probe 3, is realized by special-purpose chip temperature or electronic component with temperature effect.
The probe segment of methane probe 3 and temp probe 4 places shell 1 outside, and the line of methane probe 3 and temp probe 4 partly places shell 1 inside, is connected to accurate exciting signal source 2 and modulate circuit 5.
In the present embodiment; Methane probe 3 is the hot wire type gas sensor; The hot wire type gas sensor is made up of sensitive resistance and compensating resistance, and wherein compensating resistance and sensitive resistance have the same datum resistance, and sensitive resistance and compensating resistance are respectively as two brachium pontis of Huygens's electric bridge; The sensitive material of sensitive resistance is a tin ash, and its resistance value changes along with the variation of methane concentration around it, thereby the output voltage of Huygens's electric bridge is changed.
In the present embodiment, modulate circuit 5 mainly comprises low-frequency filter circuit and the amplifying circuit that is connected, and low-frequency filter circuit adopts the RC circuit to realize, amplifying circuit can adopt instrument amplifier to realize.Accurate exciting signal source 2 produces positive and negative DC voltage for external power source through the power source special chip, is connected to pop one's head in 3 input end of methane.
Measuring process is as shown in Figure 2, and the paddy methane concentration sensor is installed in static chamber 10 inner tip, static chamber 10 lower ending openings and in measuring process, covering on the face of land, measured rice field; Static chamber 10 bosoms are equipped with electric fan, are used for stirring its air and make it even; Air sample tap and thermometer socket are arranged at static chamber 10 tops.A period of time after the paddy methane concentration sensor energized (generally being made as 10 minutes) is the sensor warm-up phase.In the measuring process, (5 or 10 minutes) are read the numerical value of thermometer 12 and are extracted certain volume air in the static chamber 10 by ST 13 at regular intervals, detect wherein methane concentration so that sensor measurement is demarcated by gas chromatograph.
Paddy methane concentration sensor output calibration process is following:
(1) zero correction of methane probe and temp probe output can be by formula (1) and (2) expression, and wherein Vd0 is the desired voltage value of exciting signal source, is the output nominal value (like 3V) of power source special chip.
V
m1＝(V
m-V
0)*(V
d0/V
d) (1)
V
t1＝(V
t-V
0)*(V
d0/V
d) (2)
(2) temperature correction and the zero migration correction of methane probe are shown in formula (3).
V
m1＝V
m1-f(V
t1)-ΔV (3)
Wherein, F (Vt1) is the temperature characterisitic function of methane probe; Its preparation method is under laboratory environment, and methane concentration is regarded as ATMOSPHERICAL BACKGROUND concentration and remains unchanged, and sensor places a temperature adjustable space (like baking oven); Record methane probe and temp probe output result just can obtain f (Vt1) function under specified temp.Δ Vd is methane probe output zero migration, Δ V=0 ideally, and in actual applications, Δ V can be changed by the Vm output of each measurement the previous day and obtains.
The result of air sample after gas chromatograph detects who is obtained by ST 13 is regarded as methane concentration true value in the static chamber 10, can set up the predictive equation of paddy methane concentration sensor with this, obtains the methane concentration in the different static chamber 10 constantly; The stability of this predictive equation and reliability can be undertaken by cross validation.
Different paddy methane concentration constantly according to prediction obtains just can further obtain methane concentration function over time, in known quiescent state case 10, under the physical dimension situation, just can try to achieve the paddy methane emission flux.
The foregoing description is a preferred implementation of the present invention; But embodiment of the present invention is not restricted to the described embodiments; Other any do not deviate from change, the modification done under spirit of the present invention and the principle, substitutes, combination, simplify; All should be the substitute mode of equivalence, be included within protection scope of the present invention.
Claims (7)
1. a paddy methane concentration sensor system is characterized in that, comprises static chamber and paddy methane concentration sensor; Said paddy methane concentration sensor is installed in the static chamber inner tip, static chamber lower ending opening and in measuring process, covering on the face of land, measured rice field, and the static chamber bosom is equipped with electric fan, is used for stirring its air and makes it even; The paddy methane concentration sensor comprises sensor outer housing; Place sensor outer housing inner methane probe, temp probe, exciting signal source, modulate circuit and sensor interface; The probe segment of methane probe and temp probe places sensor outer housing outside; Exciting signal source is connected with temp probe with the methane probe respectively, and modulate circuit is connected with methane probe, temp probe and sensor interface respectively; Methane probe and temp probe are driven by exciting signal source, and the response signal of driving produces the output voltage V of methane probe after modulate circuit filtering, processing and amplifying
m, temp probe output voltage V
t, exciting signal source voltage V
dAnd total null voltage V
0Said voltage V
m, V
t, V
dAnd V
0Together export sensor interface to.
2. paddy methane concentration sensor according to claim 1 system; It is characterized in that: said methane probe is the hot wire type gas sensor; The hot wire type gas sensor is made up of sensitive resistance and compensating resistance, and wherein compensating resistance and sensitive resistance have the same datum resistance.
3. paddy methane concentration sensor according to claim 2 system, it is characterized in that: the sensitive material of said sensitive resistance is a tin ash.
4. paddy methane concentration sensor according to claim 1 system, it is characterized in that: said paddy methane concentration sensor also comprises interconnective data acquisition module and host computer; Sensor interface passes through cable with said voltage V
m, V
t, V
dAnd V
0Be sent to data acquisition module and carry out A/D conversion, transformation result is sent to host computer and preserves and show.
5. paddy methane concentration sensor according to claim 4 system, it is characterized in that: said data acquisition module is provided with and is no less than 4 data acquisition channels that are connected with sensor interface, and is provided with COM or the USB port that is connected with host computer.
6. paddy methane concentration sensor according to claim 1 system, it is characterized in that: said modulate circuit comprises low-frequency filter circuit and the amplifying circuit that is connected.
7. paddy methane concentration sensor according to claim 6 system, it is characterized in that: said low-frequency filter circuit is the RC circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110200030 CN102288645B (en) | 2011-07-18 | 2011-07-18 | Rice field methane concentration sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110200030 CN102288645B (en) | 2011-07-18 | 2011-07-18 | Rice field methane concentration sensor |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104634830A (en) * | 2015-01-26 | 2015-05-20 | 南京大学 | PMMA-SnO2-based thin-film gas sensor for detecting methane |
| CN105606656B (en) * | 2015-11-06 | 2020-04-21 | 上海戴维蓝普传感技术有限公司 | Hot wire type methane sensor with silicon resistance and sulfur poisoning resistance |
| CN112630268A (en) * | 2020-11-26 | 2021-04-09 | 燕山大学 | Bipolar miniature ion concentration sensor and measurement system thereof |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1036154C (en) * | 1992-02-24 | 1997-10-15 | 中国科学院大气物理研究所 | Automatic gathering and analytic system of methane |
| JP2001324463A (en) * | 2000-05-12 | 2001-11-22 | Hioki Ee Corp | Gas concentration detection sensor and gas concentration measuring apparatus |
| JP2002214176A (en) * | 2001-01-19 | 2002-07-31 | Fujitsu General Ltd | Gas detector |
| CN2911815Y (en) * | 2006-05-23 | 2007-06-13 | 张玉林 | Well self-inflam monitoring, analysing and controlling system of coal mine |
| JP2009058501A (en) * | 2007-08-08 | 2009-03-19 | Yamaha Motor Co Ltd | Gas sensor, air fuel ratio controller, and transport equipment |
| JP5046285B2 (en) * | 2007-08-29 | 2012-10-10 | 一般財団法人電力中央研究所 | Bubble counting system |
| CN101788440B (en) * | 2010-01-15 | 2011-12-28 | 清华大学 | Electronic nose used for food safety monitoring |
| CN201796024U (en) * | 2010-09-06 | 2011-04-13 | 北京市华云分析仪器研究所有限公司 | In-situ monitoring device for water body-atmosphere interface methane gas flux |
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