CN101907600B - Device for measuring mine dust concentration based on differential principle - Google Patents
Device for measuring mine dust concentration based on differential principle Download PDFInfo
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- CN101907600B CN101907600B CN2010102404285A CN201010240428A CN101907600B CN 101907600 B CN101907600 B CN 101907600B CN 2010102404285 A CN2010102404285 A CN 2010102404285A CN 201010240428 A CN201010240428 A CN 201010240428A CN 101907600 B CN101907600 B CN 101907600B
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Abstract
The invention discloses a device for measuring mine dust concentration based on a differential principle. A measurement sensitive element and a reference sensitive element are arranged together in parallel; a signal wire of an electrode of the measurement sensitive element is led out of a shielding case and connected with a first charge amplifier for charge voltage conversion; output signals comprise a valid charge signal and an interference signal; apart from the following difference, other parts of the reference sensitive element are the same as corresponding parts of the measurement sensitive element; orifices at the two ends of an insulating tube are plugged by using an insulating material, so the internal tube cavity becomes a blind cavity; the signal wire of the electrode is led out of the shielding case and connected with a second charge amplifier for charge voltage conversion; the output signal only comprises one same interference signal; and each signal is simultaneously input into a differential amplifying circuit so as to amplify the differential-mode valid signal and filter out the common-mode interference signal. The device can effectively filter out the adverse effects produced by various electromagnetic interferences on the device to improve the measurement accuracy and the flexibility.
Description
Technical field
The present invention relates to a kind of device for measuring mine dust concentration, particularly a kind of device for measuring mine dust concentration based on differential principle.
Background technology
China is big coal country, and in total Energy Mix, coal accounts for about 75%, and this situation does not have the change of essence in considerable time from now on.Each setting can produce a large amount of dust in process of production under the coal mine, and the harmfulness of Mine Dust is very big, can cause coal dust explosion, also can bring out occupational illness---pneumoconiosis simultaneously.The control dust of adopting an effective measure is an important process of Safety of Coal Mine Production, and real-time online detects the dust concentration of each setting of down-hole, is the requisite means of correctly assessing the dust prevention and control measure.
The method of measuring dust concentration at present mainly comprises the filter membrane method of weighing, β rays method, piezoelectricity crystal oscillator method, supercritical ultrasonics technology, blackness method, light extinction method, light scattering method, capacitance method etc.These measuring methods respectively have its relative merits, and the filter membrane method of weighing, the blackness method is widely used but complex operation, can not realize online detection; Because of the complicacy of colliery conditions down-hole, equipment and device with radioactive source are gone into the well, and need the approval of national correlation department, so the β rays method does not adopt in the down-hole; Piezoelectricity crystal oscillator method can be implemented in line and detects, but this method needs loaded down with trivial details sampling process, the time ductility long, measuring error is bigger, is not applied in the colliery; Capacitance method is a kind of method that obtains dust concentration through the variation of Measuring Dielectric Constant, but its sensitivity is low, can only be applied to concentrated phase conditions such as coal dust strength conveying, can not be applied under the dilute phase conditions such as mine.Light extinction method, light scattering method are the domestic and international at present generally methods of the measurement dust concentration of employing; Long-term these two kinds of methods of application proof are very sensitive in the problem of sensor internal accumulation for dust; Need the periodic cleaning sensor; Optical lens is very strong to the dependence of humidity simultaneously, and measuring error becomes big after a period of time.Therefore utilize new theory, exploring new measuring method, to overcome the problem that exists in the present measuring technique be very important.
Electrostatic method is a kind of granule density On-line Measuring Method that comes into one's own in the world over past ten years, and is domestic through introducing in the leak detection of detection and sack cleaner of pulverized coal mass flow of coal dust mixed flow that external product is mainly used in all kinds of coal-burning power plants.Its principle of work is: the material of any powder shaped is in the gas flow process; The capital produces collision and friction; Therefore powder particle can lose electronics and form particle and the particle of static electrification lotus, and along with the variation of granule density and powder flow rate, its quantity of electric charge also changes according to certain rules.Detect the carrying capacity that shifts between the static noise that produces in the particle flow process or particle and the proving installation through sensitive element, and combine the appropriate signals disposal route to realize that granule density measures.It is highly sensitive, simple in structure, non-maintaining that the electrostatic method biggest advantage is measured dust concentration, and these advantages have overcome the light extinction method that generally adopt in the particularly present colliery of other measuring methods, the shortcoming of light scattering method.
At present domestic utilize electrostatic method measure dust concentration particularly mine dust concentration be in the stage at the early-stage, only be in and utilize external product to experimentize and make an experiment the stage to the down-hole in the laboratory, also do not have one's own product.Verify through laboratory experiment, underground trials: the electrostatic measurement sensitive element that uses in the prior art; Because the dust carried charge is very faint; Its induction electric weight is also very faint, because its electrode partly is exposed in the complicated measurement environment, lacks effective anti-electromagnetic interference shielding simultaneously; Be coupled into the various electromagnetic interference (EMI) in the environment easily; Especially big one or two order of magnitude of airborne power frequency interference ratio charge signal only leans on follow-up treatment circuit to be difficult to filtering interfering effectively, and therefore how improving the sensitivity of measuring sensitive element and removing electromagnetic interference (EMI) becomes the problem of needing solution badly.
Summary of the invention
Task of the present invention is to solve the existing above-mentioned technological deficiency of mine dust concentration electrostatic method measurement mechanism in the prior art; A kind of device for measuring mine dust concentration based on differential principle is provided; Sensitive element in this device for measuring mine dust concentration is the influence of the various electromagnetic interference (EMI) of filtering effectively, helps improving its accuracy and sensitivity.
Its technical solution is:
A kind of device for measuring mine dust concentration based on differential principle; Comprise that a measurement sensitive element and one are with reference to sensitive element; Measure sensitive element and be set up in parallel together with reference to sensitive element, above-mentioned measurement sensitive element comprises insulation tube, circular ring electrode and radome, and the two ends mouth of pipe of insulation tube is open; Tube chamber is as the dust passage of flowing through in it; Circular ring electrode is nested with on the insulation tube outer tube wall, and radome cooperates airtight shielding space of formation with insulation tube, and circular ring electrode is positioned at shielding space; The signal conductor of circular ring electrode is drawn and is connected with first charge amplifier from radome and carries out the charge voltage conversion, and the output signal of the first charge voltage amplifier comprises an effective charge signal and one first undesired signal; With reference to sensitive element except that following difference; Other are identical with measurement sensitive element counterpart; The two ends mouth of pipe of insulation tube adopts the insulating material shutoff, and tube chamber becomes blind chamber in it, and the signal conductor of circular ring electrode is drawn and is connected with second charge amplifier from radome and carries out the charge voltage conversion; The output signal of the second charge voltage amplifier only comprises one second undesired signal; First undesired signal is identical with second undesired signal, and first charge amplifier and second charge amplifier are connected with a differential amplifier circuit simultaneously, and above-mentioned effective charge signal, first undesired signal and second undesired signal be the input difference amplifying circuit simultaneously; And by differential amplifier circuit amplification differential mode useful signal, filtering common mode interference signal.
Above-mentioned differential amplifier circuit connects signal conditioning circuit, will be converted into the normalized current signal of 4~20mA from the input signal of difference amplifying circuit by signal conditioning circuit.
Above-mentioned first charge amplifier is identical with second charge amplifier, is ultralow bias current differential operational amplifier.
Above-mentioned first, second charge amplifier, differential amplifier circuit, and signal conditioning circuit all is arranged in the box cabin, the box cabin be fixed on from the below measure sensitive element with reference to sensitive element on the radome at position, the box cabin is provided with ground wire.
Above-mentioned device for measuring mine dust concentration also comprises the extractor fan that can impel dust uniflux in the dust of measuring sensitive element is flowed through passage.
The present invention has following useful technique effect:
The present invention takes a measurement sensitive element and one with reference to sensitive element; Electrode part in each sensitive element can prevent by electromagnetic interference (EMI); Can prevent that again airborne moisture and dust from getting into invasion and attack; The various electromagnetic interference (EMI) of filtering are to the harmful effect of its generation effectively, thereby improve accuracy of measurement and sensitivity.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is described further:
Fig. 1 is the structural principle synoptic diagram of one embodiment of the present invention.
Fig. 2 shows the measurement sensitive element in Fig. 1 mode.
Fig. 3 shows first, second charge amplifier and difference level amplification circuits and electrical connection thereof in Fig. 1 mode.
Fig. 4 shows first, second charge amplifier, the electrical connection of difference level amplifying circuit and signal conditioning circuit.
Embodiment
In conjunction with Fig. 1, Fig. 2, Fig. 3 and Fig. 4; A kind of device for measuring mine dust concentration based on differential principle; Comprise that a measurement sensitive element 1 and one are with reference to sensitive element 2; Measure sensitive element 1 and be set up in parallel together with reference to sensitive element 2; Be set up in parallel and both can have referred to measure sensitive element 1 with the situation that tightly abuts in reference to sensitive element 2 together, this situation is as shown in Figure 1, can refer to measure sensitive element 1 again and separate a little, is fixed on the situation on a connection piece with reference to sensitive element 2; Also can refer to measure sensitive element 1 and the situation of separating, be fixed on diverse location on the same measurement point with reference to sensitive element 2, tightly abutting in aforementioned two sensitive elements is optimal way together.Above-mentioned measurement sensitive element 1 comprises insulation tube 101, circular ring electrode 102 and radome 103; The two ends mouth of pipe of insulation tube 101 is open; Tube chamber 104 is as the dust passage of flowing through in it; Circular ring electrode 102 is nested with on insulation tube 101 outer tube walls, and radome 103 cooperates airtight shielding space of formation with insulation tube 101, and circular ring electrode is positioned at shielding space; Can prevent that electromagnetism is to Effect on Electrode; Can prevent that again airborne moisture and dust from getting into the influence of invasion and attack, the signal conductor of circular ring electrode 102 is drawn and is connected with first charge amplifier 3 from radome and carries out the charge voltage conversion, and the output signal of the first charge voltage amplifier 3 comprises an effective charge signal and one first undesired signal.With reference to sensitive element 2 except that following difference; Other are identical with above-mentioned measurement sensitive element 1 counterpart; The two ends mouth of pipe of insulation tube 201 adopts insulating material such as unit of plastic or sheet 205 shutoff, interior tube chamber 204 since two ends be closed and become blind chamber, not as the dust passage of flowing through; The signal conductor of circular ring electrode 202 is drawn and is connected with second charge amplifier 4 from radome and carries out the charge voltage conversion, and the output signal of the second charge voltage amplifier 4 only comprises one second undesired signal.Above-mentioned first charge amplifier 3 is identical with second charge amplifier 4; Be ultralow bias current differential operational amplifier; First undesired signal is identical with second undesired signal, and first charge amplifier and second charge amplifier are connected with a differential amplifier circuit 5 simultaneously, and above-mentioned effective charge signal, first undesired signal and second undesired signal be input difference amplifying circuit 5 simultaneously; And by differential amplifier circuit 5 amplification differential mode useful signals, filtering common mode interference signal.Above-mentioned differential amplifier circuit 5 connects signal conditioning circuit, will be converted into the normalized current signal of 4~20mA from the input signal of difference amplifying circuit by signal conditioning circuit.Above-mentioned first, second charge amplifier 3,4; Differential amplifier circuit 5; And signal conditioning circuit 6 all is arranged in the box cabin 6; Box cabin 6 be fixed on from the below measure sensitive element 1 with reference to sensitive element 2 on the radome at position, box cabin 6 is provided with ground wire, so that keep good ground state.
Remake further explanation in the face of above-mentioned related content down:
Above-mentioned circular ring electrode 102,202 should be made up of the favorable conductive material, preferred copper sheet or stainless steel substrates, and radome 103 is in order to realize electromagnetic screen and corrosion-resistantly should to select stainless steel material for use.Insulation tube 101,201 adopts corrosion resistant Teflon material to process.Radome and insulation tube corresponding position are combined closely and are promptly formed an airtight shielding space, prevent that water in air branch and dust from getting into the induction electric weight of regional effect electrode between insulation tube and the radome.Circular ring electrode closely is wrapped on the insulation tube, records the carried charge of dust through contactless electric charge induction principle.The arrow direction is a wind direction under the mine among Fig. 2, should extractor fan be installed at an end of measuring sensitive element under the calm condition and guarantee dust uniflux in the dust of measurement sensitive element is flowed through passage.
Above-mentioned first, second charge amplifier can be taked the OPA129 amplifier, and being used for charge conversion is voltage signal.The OPA129 amplifier is the ultralow bias current differential operational amplifier that American TI Company is produced, and its typical bias current is generally 0.1PA, and such characteristic makes it be fit to very much constitute charge amplifier.Charge amplifier comes down to negative-feedback amplifier among Fig. 3, R1 wherein, and CI is a feedback parameter, supposes that the quantity of electric charge that the electrode induction obtains is Q, then charge amplifier is output as:
The enlargement factor of
charge amplifier is confirmed by C1; The low-frequency cut-off frequency of charge amplifier
is because induced charge is very faint; Be generally the pF rank; Therefore feedback capacity is chosen as 1nF; For the low-frequency cut-off frequency that guarantees that charge amplifier is enough low; Selecting feedback resistance is 1G Ω; Can guarantee that the charge amplifier low-frequency cut-off frequency is 0.16Hz this moment, and charge amplifier is output as the millivolt level.The signal of two-way charge amplifier output comprises that the effective charge signal of differential mode and the undesired signal of common mode are first undesired signal and second undesired signal; Wherein charge amplifier is because input bias current is very little; So it is very responsive to noise; Usually noise signal can exceed one or two order of magnitude than useful signal, and above-mentioned differential amplifier circuit adopts instrument amplifier AD620, and AD620 has higher common-mode rejection ratio; Have less input temperature to float and less offset voltage, gain margin is big and can carry out regulating gain through the size of regulating outer meeting resistance R3.And the AD620 signal to noise ratio (S/N ratio) is high, and the characteristics that noise figure is little especially are fit to the faint characteristics of this device input signal.With two-way is the positive-negative input end that the output of first, second charge amplifier is connected to AD620 respectively, filtering common mode interference signal, the enlargement factor of the size adjustment amplifier through adjustment R3, the signal of final output volt level.
Above-mentioned signal conditioning circuit comprises a voltage conversion circuit 7 and a two-wire system V/I transmitter 8; The volt level signal of above-mentioned differential amplifier circuit output is adjusted into the voltage signal of 0.4-2V through voltage conversion circuit; Change 4~20mA normalized current signal into through two-wire system V/I transmitter, be sent to host computer then and carry out acquisition process.The benefit that adopts 4~20mA normalized current signal is can grow Distance Transmission and antijamming capability is strong.
Claims (5)
1. device for measuring mine dust concentration based on differential principle; Be characterised in that it comprises that a measurement sensitive element and one are with reference to sensitive element; Measure sensitive element and be set up in parallel together with reference to sensitive element, above-mentioned measurement sensitive element comprises insulation tube, circular ring electrode and radome, and the two ends mouth of pipe of insulation tube is open; Tube chamber is as the dust passage of flowing through in it; Circular ring electrode is nested with on the insulation tube outer tube wall, and radome cooperates airtight shielding space of formation with insulation tube, and circular ring electrode is positioned at shielding space; The signal conductor of circular ring electrode is drawn and is connected with first charge amplifier from radome and carries out the charge voltage conversion, and the output signal of the first charge voltage amplifier comprises an effective charge signal and one first undesired signal; Comprise insulation tube, circular ring electrode and radome with reference to sensitive element; The two ends mouth of pipe of insulation tube adopts the insulating material shutoff; Tube chamber becomes blind chamber in it; The signal conductor of circular ring electrode is drawn and is connected with second charge amplifier from radome and carries out the charge voltage conversion, and the output signal of the second charge voltage amplifier only comprises one second undesired signal, and first undesired signal is identical with second undesired signal; First charge amplifier and second charge amplifier are connected with a differential amplifier circuit simultaneously; Above-mentioned effective charge signal, first undesired signal and second undesired signal be the input difference amplifying circuit simultaneously, and amplifies differential mode useful signal, filtering common mode interference signal by differential amplifier circuit.
2. the device for measuring mine dust concentration based on differential principle according to claim 1; It is characterized in that: said differential amplifier circuit connects signal conditioning circuit, will be converted into the normalized current signal of 4~20mA from the input signal of difference amplifying circuit by signal conditioning circuit.
3. the device for measuring mine dust concentration based on differential principle according to claim 1 is characterized in that: said first charge amplifier is identical with second charge amplifier, is ultralow bias current differential operational amplifier.
4. the device for measuring mine dust concentration based on differential principle according to claim 2; It is characterized in that: said first, second charge amplifier; Differential amplifier circuit; And signal conditioning circuit all is arranged in the box cabin, the box cabin be fixed on from the below measure sensitive element with reference to sensitive element on the radome at position, the box cabin is provided with ground wire.
5. the device for measuring mine dust concentration based on differential principle according to claim 1 is characterized in that: said device for measuring mine dust concentration also comprises the extractor fan that can impel dust uniflux in the dust of measuring sensitive element is flowed through passage.
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CN103454196B (en) * | 2013-09-27 | 2016-02-24 | 山东科技大学 | Device for measuring mine dust concentration and measuring method thereof |
CN103454195B (en) * | 2013-09-27 | 2016-08-17 | 山东科技大学 | A kind of mine dust concentration sensor based on electrostatic induction |
CN104237089B (en) * | 2014-09-15 | 2018-07-13 | 山东科技大学 | A kind of network sensor |
CN104655214A (en) * | 2015-01-29 | 2015-05-27 | 兖矿水煤浆气化及煤化工国家工程研究中心有限公司 | Dense-phase pulverized coal mass flowmeter |
CN105023191B (en) * | 2015-07-24 | 2019-01-22 | 金川集团股份有限公司 | A kind of online recurrence calculation method of metallurgical furnace kiln flue dust incidence |
CN106442243B (en) * | 2016-09-27 | 2019-03-05 | 东南大学 | It is a kind of for detecting the device and method of dust concentration |
CN106943142A (en) * | 2017-03-16 | 2017-07-14 | 深圳麦格米特电气股份有限公司 | A kind of electroretinogram(ERG)The signal amplifier of portable detection system |
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CN101038190A (en) * | 2006-03-13 | 2007-09-19 | 杜豫生 | Method and device for detecting micro-charge type online dust and detector pollution |
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JPS56143946A (en) * | 1980-04-11 | 1981-11-10 | Toshiba Corp | Dust tester |
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CN2161924Y (en) * | 1993-05-20 | 1994-04-13 | 清华大学 | Density detecting device |
CN101038190A (en) * | 2006-03-13 | 2007-09-19 | 杜豫生 | Method and device for detecting micro-charge type online dust and detector pollution |
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