EP0232382A4 - Chemical analysis by controlled sample modulation and detection correlation. - Google Patents
Chemical analysis by controlled sample modulation and detection correlation.Info
- Publication number
- EP0232382A4 EP0232382A4 EP19860905092 EP86905092A EP0232382A4 EP 0232382 A4 EP0232382 A4 EP 0232382A4 EP 19860905092 EP19860905092 EP 19860905092 EP 86905092 A EP86905092 A EP 86905092A EP 0232382 A4 EP0232382 A4 EP 0232382A4
- Authority
- EP
- European Patent Office
- Prior art keywords
- stream
- modulator
- characteristic
- substance
- methanol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000126 substance Substances 0.000 title claims abstract description 73
- 238000001514 detection method Methods 0.000 title claims description 12
- 238000004458 analytical method Methods 0.000 title abstract description 11
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 75
- 239000007789 gas Substances 0.000 claims abstract description 62
- 238000000034 method Methods 0.000 claims abstract description 58
- 230000004044 response Effects 0.000 claims abstract description 37
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 20
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 20
- 239000000446 fuel Substances 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims description 37
- 230000000694 effects Effects 0.000 claims description 18
- 230000003197 catalytic effect Effects 0.000 claims description 5
- 230000004048 modification Effects 0.000 claims description 4
- 238000012986 modification Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 239000004215 Carbon black (E152) Substances 0.000 claims description 3
- 230000004888 barrier function Effects 0.000 claims description 3
- 238000002485 combustion reaction Methods 0.000 claims description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 2
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 2
- 239000001110 calcium chloride Substances 0.000 claims description 2
- 230000005264 electron capture Effects 0.000 claims description 2
- 239000003502 gasoline Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 230000005855 radiation Effects 0.000 claims description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims 2
- 238000007385 chemical modification Methods 0.000 claims 2
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 claims 1
- 238000001914 filtration Methods 0.000 claims 1
- 238000007781 pre-processing Methods 0.000 claims 1
- 238000005316 response function Methods 0.000 claims 1
- 230000008569 process Effects 0.000 description 23
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 16
- 239000003570 air Substances 0.000 description 10
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 238000004817 gas chromatography Methods 0.000 description 7
- 239000003054 catalyst Substances 0.000 description 6
- 238000004587 chromatography analysis Methods 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- 230000002596 correlated effect Effects 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 230000035945 sensitivity Effects 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000008246 gaseous mixture Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 231100000331 toxic Toxicity 0.000 description 3
- 230000002588 toxic effect Effects 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 150000001299 aldehydes Chemical class 0.000 description 2
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 2
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 2
- 230000004069 differentiation Effects 0.000 description 2
- 239000002737 fuel gas Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000000063 preceeding effect Effects 0.000 description 2
- 238000011002 quantification Methods 0.000 description 2
- 230000003252 repetitive effect Effects 0.000 description 2
- 230000000979 retarding effect Effects 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 150000003464 sulfur compounds Chemical class 0.000 description 2
- 150000003573 thiols Chemical class 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000000112 cooling gas Substances 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010892 electric spark Methods 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000005184 irreversible process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000001603 reducing effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0062—General constructional details of gas analysers, e.g. portable test equipment concerning the measuring method or the display, e.g. intermittent measurement or digital display
Definitions
- This invention relates to a method and apparatus for differentiating between two or more chemical components or classes of chemical components in a gaseous mixture and more particularly to a method and apparatus for controlled modulation of a characteristic of at least one of two or more components to be differentiated, then detecting the presence of the one or more components with a suitable detecting means, and differentiating among the components by correlating the detected signal with the controlled modulation to identify the component or components that were to be identified.
- the method and apparatus has particular application to the identification and differentiation of components in mixtures of gaseous components in a continuous stream of the mixture and where individual gases within the mixture are not easily distinguishable by a single detection process.
- Chromatography can be a valuable means for identifying components in the continuous stream if there were a way to seperate and identify the individual components of the stream as they passed through the detector of the chromatograp .
- the present invention proposes a method and apparatus for accomplishing such a seperation and identification.
- a continuous stream containing components of at least two substances to be distinguished is passed through a continuous processing system wherein a characteristic of at least one of the substances is modulated with respect to others of the components in the stream and the presence of the component is detected within the system in a manner that responds to the modulation of the characteristic.
- the modulation of the characteristic is done in a predetermined manner and the detected response is compared to the predetermined modulation in a manner to correlate the response with the modulation to identify the component subject to the controlled modulation.
- detection and correlation process the sensitivity of the system is enhanced and the presence of otherwise indistinguishable components may be identified.
- the present invention is a system and apparatus that will permit the identification and at least relative quantification of components of a continuously flowing stream of a mixture of components.
- the invention has particular application to the analysis of vehicle exhaust gases and is useful in the analysis of exhaust gases from vehicles operating on fuels that contain methanol.
- Prior art methods for the analysis of such gases have been slow and inaccurate because the detection of methanol and hydrocarbons in the presence of each other in a gas mixture can not be accomplished with generally the same techniques or processes.
- the exhaust gases in a continuous stream are passed to a detector through a modulator that effects a characteristic of at least one of the gases of the stream in a manner that can be detected by the response of the detector.
- the modulation at the modulator and the response at the detector are then cross-correlated to produce a correlation signal which represents the presence or quantification of the component of the gas stream that was modified in the modulation process. If the gases of the mixed stream respond differently to the modulation process, the response of the detector will vary in accord with that difference in modulation and the correlation of the response to the modulation will produce a correlation signal that can identify and distinguish the different gases of the mixture.
- the object of the present invention is a method and apparatus that may be used to identify and distinguish components of a mixture.
- a further object of the present invention in accord with the foregoing object is a method and apparatus that will permit the identification of at least one substance in the presence of another substance by a process that modulates a characteristic of one of the substances in a detectable manner and the detection of a response that may be correlated with the modulation to identify the one substance in the presence of the other.
- the present invention contemplates physical and chemical modulations of the one substance as a means for producing a detector response that may be correlated with the modulation process to identify the presence of the one substance.
- FIG. 1 is a schematic block diagram illustration of the process and elements used in the performance of the present invention.
- FIG.2 is a block diagram of a form of apparatus useful in modulating a sample stream in the performance of the present invention.
- FIG. 3 is a block diagram of another form of apparatus useful in modulating a sample stream in accord with the present invention.
- FIG. 4 is a block diagram of the process of the present invention as used in the analysis of automotive vehicle exhaust gases .
- FIG. 5 is a block diagram of an apparatus capable of performing all of the steps of the method of the present invention in the analysis of a sample substance.
- FIG. 6 is a representation of an output correlation response that might be produced in performing the method of the present invention.
- the method and apparatus of the present invention comprises a system for differentiating between two or more chemical components or classes of chemical components in a gaseous mixture.
- the double lines between blocks are intended to illustrate passages for the flow of the gaseous mixture while the dotted lines are intended to illustrate operating control or signal channels and solid lines are energization connections.
- the invention includes four parts as shown in the block diagram of FIG. 1 where a gas mixture to be analyzed, as represented by the sample 10, is passed as a continuous stream through a modulator 12 where a characteristic, such as the gaseous concentration, of a component or component class of interest is intermittently modulated to an extent differing from the modulation of a characteristic of other components of the sample stream.
- the gas mixture with the component or components having modulated characteristics is then passed from the modulator to a transducer or detector 14 causing the generation of a response whose magnitude varies according to the concentration of the components in the gas stream.
- FIG. 1 shows a filter 16 in phantom lines between the modulator 12 and the transducer 14 to indicate that such an element may be used as a part of the process but that the filter is not essential to the basic method.
- a signal source 18 is operationally connected to the modulator 12 to control the operation of the modulator in a predetermined manner or controlled sequence.
- the control of the modulator in that manner causes a series of changes or modifications of the characteristics in the gas stream that subsequently lead to corresponding changes in the output response or signal of the transducer 14.
- the output response of the transducer 14 is fed to a correlator 20.
- the correlator 20 is operationally interconnected with the signal source 18 so as to receive a representation of the modulating operation or control sequence of the modulator 12. As illustrated, a representation of the correlation produced in the correlator 20 is supplied as an input signal to a display or recorder at 22.
- the apparatus of FIG. 1 is capable of modulating a characteristic of at least a component of the gaseous sample by a modulator 12 controlled in a predetermined manner by a signal source 18 in a manner that will be detectable in the transducer 14 and the transducer response is fed to a correlator 20 along with the signal from the signal source for the purpose of producing an output signal that will represent the presence of the component that was to be identified in accord with the correlation of the detected response to the controlled modulation.
- the modulator 12 will be designed to accomplish a desired modification or modulation of a particular component or components of the sample stream and the transducer will respond with an output response related to the presence of the particular conponent or components of the sample stream.
- the transducer responds to the concentration of the components passing through it and its output response is modulated according to modulation of the components of the sample stream produced in the modulator.
- the "raw" response signal represents the transducer's response to all the components in the gas stream and as such is not a response to single elements of the stream. However, when the response signal is correlated with the modulation signal, the correlation response will represent the effect of the modulator on the characteristics of a particular component or components of the sample stream in accord with the specific design or control, of the modulator.
- the system may be calibrated for components of interest by seperate repetition of the above described process, in which the gas mixture to be analyzed is replaced by a gas mixture containing one or more specific components in known concentration.
- the calibration process may be repeated with additional calibration mixtures of various known concentrations to develop a calibration curve that permits the sample gas
- the correlator output signal to the display 22 may be displayed or recorded in various forms, and converted by -, r- computation to units of concentration for the components in the gas mixture.
- the filter unit 16 illustrated in the diagram may be useful for certain types of mixtures when it may be desirable to 2 remove or alter certain chemical components or signals carried by such components that could produce signals at the transducer.
- Use of a filter can result in greater specificity or precision in the correlation process at the correlator 20.
- the filter may take many forms in both chemical and physical senses.
- the modulator may take many forms that will be effective to modulate a chemical characteristic of a component passing through it. It may be: 3Q -a short bed of granular solids that is capable of absorbing, oxidizing, reducing, complexing, or otherwise removing or altering components from the sample gas mixture;
- FIG. 2 and 3 illustrate examples of systems with thermal and with catalytic modulators.
- the sample stream passes through a thermal modulator 24 formed by placing a conductive coating 26 around a portion of a chromatograph column 28.
- the thermal coating is energized from a power supply through a switch 32; the switch 32 is controlled by a microprocessor 34 to cause modulation of the desired characteristic of the sample stream.
- the gas stream passes through a detector 36, and signals from the detector and the microprocessor are supplied to a correlator 38 to produce the desired correlation signal.
- the sample steam is seperated into two portions. One portion of the sample stream passes to a detector 40 through a valve 42 and a catalyst tube 44 collectively functioning as a modulator.
- the other portion- of the sample stream passes directly to the detector 40 through a valve 46.
- the catalyst tube 44 continuously modulates _ a characteristic of the components passing through it while the valve adds a time related control.
- the valves 42 and 46 are two way valves operating to pass the sample stream to the detector 40 or to discard or waste in accord with a predetermined manner prescribed by a microprocessor 48. As with FIG. 1 and 2 the output response of the detector 40 and the control signal of the microprocessor 48 are supplied to a correlator, not shown, to produce the desired correlation signal.
- the operation of the modulator may be a reversible or an irreversible process, and in the irreversible case the modulation may be the destruction or chemical transformation of a particular component of the gas stream.
- the modulator accomplishes its modulation by interrupting the above operations, using heating, cooling, intermittent sparking or illumination, or other means dependent on the type of modulator.
- modulators in series, each being the same or different, with different thermal histories or of different types .
- Possible granular solids for a modulator include calcium chloride and cobolt chloride.
- the transducer or detector 14 may be any device that is capable of giving an electrical signal representative of the components of interest in the gas mixture that differs from that of the mixture not containing those components.
- detectors used in the practice of gas analysis and particularly in gas chromatography from which a suitable type may be selected for the particular application of. interest. Examples are:
- thermo conductivity detector thermo conductivity detector
- ECD electron capture detector
- PID photoionization detector
- the modulator signals are 10 intermittent pulses that may be generated by a computer, a microprocessor, a tape recorder, a strobe light, or even by a mechanical device analogous to a rotary switch.
- the intermittent pulses are not necessarily at uniform time intervals or of uniform duration. They actuate the modulator 12 by switching on a heater; by opening a solenoid valve to supply cooling gas; by initiating an electrical spark; by opening or closing a lamp shutter; or by other analogous means appropriate to the type of modulator.
- the sequence of actuation of the modulator is retained for use in the correlation process.
- the central part of the system is the correlator 20 that correlates the modulator signal from signal source 18 with the signal from transducer 14 to produce the information desired, the concentration of the component or class of interest.
- the known sequence of modulator signals and the measured response signals of the detector are treated to seperate the signals due to that component or class fromthe other extraneous signals from the detector. In the simplest case this may involve little more than subtracting the modulator signal from the detector signal, after appropriate scaling or shaping. More elaborate means are cross-correlation or Fourier transformation. Both are mathematical techniques for extracting the information carried by the substance that was modulated from the transducer signal noise caused by non-modulated substances.
- the correlation process mayproduce a positive ormegative signal response as the effect of the modulation on the sample substance is detected in the detector and correlated with the modulation process.
- sample gas mixture is exhaust gas diluted with air
- component of interest is methanol
- a short thermal modulator 54 which may be in the form of a tube with a surface heater and containing a bed of solid adsorbant, a complexing agent, or an oxidation catalyst having greater activity toward methanol than hydrocarbon.
- L Q detector 56 in this system is shown as a flame ionization detector.
- the thermal modulator 54 is energized by power supply 58 through switch 60 under the control of a microprocessor 62.
- the response signal from the detector 56 and the control signal from the microprocessor 62 are supplied to the correlator 64
- a modulator 12 suitable for the chemical class of interest for example an oxidation catalyst for aldehydes (which are readily oxidized); a transducer 14 such as a FID or TCD; a signal source 18; and the correlator 20.
- a filter in the form of a simple gas n chromatographic column of a type suitable for the seperation of the chemical class of interest into its individual components. Identifying these classes of components may require a somewhat higher complexity in the correlation process and a more elaborate output system, because of the greater number of
- Methane is the principal component of natural gas. Knowledge of its concentration in air is important either as an indication of sub-surface gas generation (natural seeps or landfill generation) or of leaks in industrial distribution systems. In this determination the main constituent is air and there are often other hydrocarbons (heavier than methane) present.
- the four parts of the invention for performing this determination consist of a modulator 12, preferrably of the thermal type with an oxidation catalyst or an adsorbent (methane is unique among hydrocarbons in its oxidation and absorption properties); a transducer 14 of a suitable type such as FID or TCD; a signal source 18 and a microprocessor similar to that described for the methanol system.
- the invention's component parts are a thermal modulator 70 consisting of a short segment of a " capillary quartz chromatographic column coated with electrically conductive paint; a detector or transducer 72 in the form of either a FID or a TCD (both are effective and each has advantages for particular applications); a microprocessor 74 providing signal pulses to switch power from a D.C- power supply 76 to the heater coating in the thermal modulator; and a correlator, in this form probably within the microprocessor, for demodulating the signals for the various hydrocarbons by cross-correlation with the signal pulses to the thermal modulator.
- a thermal modulator 70 consisting of a short segment of a " capillary quartz chromatographic column coated with electrically conductive paint
- a detector or transducer 72 in the form of either a FID or a TCD (both are effective and each has advantages for particular applications)
- a microprocessor 74 providing signal pulses to switch power from a D.C- power supply 76 to
- the sample flows through the system continuously passing here through a filter 78, a pump 80, a switching valve 82, a control valve 84, and a pressure gauge 86 in its route to the thermal modulator 70.
- the thermal modulator is connected to the detector 72 through a column 90.
- a source of calibration gas 88 is provided as an alternate input to the switching valve 82 to provide for a calibration run through the system.
- the thermal modulator 70, the detector 72, and the column 90 are enclosed within insulating barriers 92, 94 and 96, respectively, to provide for maintainence and control of the heat within those barriers .
- the volume surrounding the thermal modulator would be maintained at ambient temperature
- the volume around the columns would be maintained at about 50 degrees centigrade
- the volume around the detector at between 60 to 100 degrees centigrade.
- the system comprises a modulator making use of the affinity of certain metals such as silver for chlorine atoms, modulated by temperature pulsing; a detector probably of the TID type, which may be operated in a halogen mode; and a microprocessor for pulse control and demodulation by cross- correlation or other methods.
- a modulator making use of the affinity of certain metals such as silver for chlorine atoms, modulated by temperature pulsing
- a detector probably of the TID type, which may be operated in a halogen mode
- a microprocessor for pulse control and demodulation by cross- correlation or other methods.
- a chemical filter or simple elementary gas chromatographic column in the input stages will be helpful.
- Aromatic Hydrocarbons in Vehicle Exhaust A system operated according to the present invention for this measurement would be simpler that the previous description of a system for measuring low molecular weight hydrocarbons . It could be made in two versions, one aimed at determination of benzene only, and another to determine also the higher homologs of benzene. The difference between this system and the system for identifying aromatics would be the use of a PID transducer, which can be made more specific for aromatic hydrocarbons relative to other hydrocarbons. Generally, all other elements would be the same. If the system was to be used for benzene detection only, the filter and the cross-correlator would be even more simplified to give shorter initial delays in response.
- Volitile Sulfur Compounds in Air or Natural Gas Hydrogen sulfide and other organic sulfide and thiols in air are toxic nuisances.
- Certain thiols and sulfides are also used in various combinations as trace additives in natural gas and liquefied petroleun gas to give warning of leaks.
- the present invention may be used to monitor air concentrations or to analyze fuel gases for the concentrations of these compounds.
- the system to perform the invention would comprise a modulator, probably based on the affinity of certain metals such as cadmium for sulfur; a transducer specific for sulfur, probably a flame photometric detector (FPD); a microprocessor for modulator control and demodulation such as by cross-correlation; and a chemical filter consisting of a simple gas chromatographic column designed for separation of the volitle sulfur compounds.
- a modulator probably based on the affinity of certain metals such as cadmium for sulfur
- FPD flame photometric detector
- microprocessor for modulator control and demodulation such as by cross-correlation
- a chemical filter consisting of a simple gas chromatographic column designed for separation of the volitle sulfur compounds.
- the detector will require modification because of the totally combustible nature of the gas mixture.
- a supplemental supply of hydrogen gas to the detector will probably be necessary for either application.
- the output may be displayed in the form of a digital output of concentration of the particular components detected or, if the filter is a chromatography column, a conventional gas chromatogram as shown in FIG. 6.
- the chromatogram because it is derived from the correlation of modulated and detected signals, includes both positive and negative signal representations.
- the modulator modulates an identifiable characteristic of a sample component by retarding and releasing a sample component in accord with the modulator ' s predetermined control, that modulation is detectable as the detector responds to all components within the sample stream.
- the retarding and releasing may result in sequential positive and negative (or reverse) correlation signals for identifying substances or components.
- the microprocessor can also be used for computations such as the BTU content (heating value) of the gas mixture or other desired computations.
- the sample is introduced as a batch or slug of gas (sometimes by vaporization of a liquid in the inlet of the instrument).
- the sample is them passed through a column with- adsorption properties, where the components of the gas mixture are separated and then detected individually as they emerge at the far end of the column.
- the sample gas mixture is introduced continuously to the ' instrument, eliminating the need for manual or automated operation of valves (or syringe injection of liquids) .
- this invention gives responses in a few seconds at most, and with a filter the results are read out at intervals of as small as one second, after an initial delay
- a filter can impose an initial delay of a few seconds to a few minutes; the longer delay results from a filter which is a chromatographic column.
- the conventional gas chromatograph requires the same lag of seconds to minutes after each sample introduction .
- the present invention also offers greater sensitivity because the sample is continuous ;i.e. without overloading the system, more information (total sample) is used to calculate the result.
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- Medicinal Chemistry (AREA)
- Food Science & Technology (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
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Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US76602285A | 1985-08-15 | 1985-08-15 | |
US766022 | 1985-08-15 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0232382A1 EP0232382A1 (en) | 1987-08-19 |
EP0232382A4 true EP0232382A4 (en) | 1988-01-28 |
Family
ID=25075162
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP19860905092 Withdrawn EP0232382A4 (en) | 1985-08-15 | 1986-08-06 | Chemical analysis by controlled sample modulation and detection correlation. |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0232382A4 (en) |
JP (1) | JPS63500674A (en) |
WO (1) | WO1987001204A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB8711573D0 (en) * | 1987-05-15 | 1987-06-17 | Lion Lab Ltd | Measuring apparatus |
DE3879897T2 (en) * | 1987-12-11 | 1993-10-14 | Horiba Ltd | Method and device for analyzing liquids using multi-liquid modulation methods. |
GB2251070B (en) * | 1989-07-06 | 1993-01-20 | Secr Defence | A detector for monitoring low molecular weight compounds |
WO1991001001A1 (en) * | 1989-07-06 | 1991-01-24 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | A detector for monitoring low molecular weight compounds |
US8596380B2 (en) | 2010-12-01 | 2013-12-03 | Chevron U.S.A. Inc. | System and method for assessing hydrogen sulfide in a hydrocarbon extraction well in situ in an ongoing manner |
ES2486891B1 (en) * | 2013-01-17 | 2015-10-27 | Sgenia Soluciones Sl | Method of analysis of a gas and artificial nose |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4140005A (en) * | 1977-03-22 | 1979-02-20 | The Regents Of The University Of Minnesota | Method and instrument for continuous monitoring of aerosols |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1926937A1 (en) * | 1968-12-19 | 1970-07-09 | Junkalor Dessau | Method and device for the selective ionization analysis detection of toxic components in air and other gases |
US3753653A (en) * | 1971-03-01 | 1973-08-21 | N Soulages | Method and apparatus for gaseous-phase chemical reaction analysis |
US3711251A (en) * | 1971-04-14 | 1973-01-16 | Insurance Inst For Highway Saf | Detection of organic vapor contaminants in air |
GB1482611A (en) * | 1974-04-08 | 1977-08-10 | Lovelock J | Selective detection of a component in an atmosphere |
US3967933A (en) * | 1974-05-23 | 1976-07-06 | Monitor Labs, Inc. | Dual channel nitrogen oxides analyzer |
JPS5156284A (en) * | 1974-11-13 | 1976-05-17 | Hitachi Ltd | Chitsusosankabutsu oyobi anmonia ofukumu haigasuchuno anmonianodobunsekiho oyobi sono sochi |
HU174711B (en) * | 1976-04-20 | 1980-03-28 | Egyt Gyogyszervegyeszeti Gyar | Process and equipment for the analysis of liquid samples |
US4197177A (en) * | 1978-05-22 | 1980-04-08 | Proctor Albert E | Apparatus for analysis of nitrogen oxides |
EP0135135A3 (en) * | 1983-08-15 | 1987-04-15 | Honeywell Inc. | Method and apparatus for trace gas detection |
-
1986
- 1986-08-06 EP EP19860905092 patent/EP0232382A4/en not_active Withdrawn
- 1986-08-06 JP JP50437286A patent/JPS63500674A/en active Pending
- 1986-08-06 WO PCT/US1986/001625 patent/WO1987001204A1/en not_active Application Discontinuation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4140005A (en) * | 1977-03-22 | 1979-02-20 | The Regents Of The University Of Minnesota | Method and instrument for continuous monitoring of aerosols |
Non-Patent Citations (2)
Title |
---|
MEASUREMENT AND CONTROL, vol. 5, no. 9, September 1972, pages 351-353; G.C. MOSS et al.: "Correlation techniques applied to gas chromatography: a re-appraisal" * |
See also references of WO8701204A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1987001204A1 (en) | 1987-02-26 |
EP0232382A1 (en) | 1987-08-19 |
JPS63500674A (en) | 1988-03-10 |
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