Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1999-09-21
2001-10-30
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S094000, C422S051000, C422S051000, C422S070000, C422S078000, C422S080000, C422S082010, C422S082050, C422S082090, C422S091000, C422S098000
Reexamination Certificate
active
06309604
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns an apparatus for analyzing a gas composition combining spectrophotometry and flame ionization detection.
SUMMARY OF THE INVENTION
The invention particularly, but not exclusively, applies to the analysis of a gas composition in which the searched elements may also include elements generating light emissions characterizing for example sulfur, phosphorus, slightly emissive elements (even non-emissive) such as hydrocarbons.
It is generally known that flame spectrophotometry is a method for spectrographically analyzing radiation generated by the flame of a gas mixture including the elements to be analyzed and a combustive gas, such as hydrogen. Said analysis is carried out by isolating the radiations characterizing the searched elements and by measuring these radiations by photometric means. This method is particularly useful for detecting elements, such as sulfur, phosphorus, sodium and lithium.
So as to apply this process to certain elements not generating characteristic luminous emission, for example chlorine, it is necessary prior to combustion to make these elements react with a reactive element in order to obtain a compound generating a detectable or identifiable luminous emission.
Thus, as regards chlorine, the first reaction which aims at generating chlorides is carried by embodying a first combustion in a reducing medium in the presence of a reactive metal such as copper or indium, a gas mixture including hydrogen and the gas to be analyzed.
The gas mixture originating from said first combustion process is submitted to a second combustion process, but this time in an oxidizing medium which generates a light emission from which the spectrophotometric analysis is effected.
Similarly, the flame ionization detection (FID) analysis methods uses a burner in which the combustion of the sample to be analyzed in a combustive oxidant gas, such as hydrogen, is embodied in an oxidizing environment. Electrodes are therefore placed at the level of the combustion chamber of the burner so as to be able to measure the conductivity of the zone where combustion is generated.
Said measure makes it possible to detect the presence of combustible constituents in the sample and particularly organic matter, such as hydrocarbons or hydrocarbon derivatives. The combustion of this organic matter in fact produces between the measurement electrodes an ionization current in relation with the organic matter concentration. This method can be extended to a wider range of compounds by adding an agent, such as an alkaline salt which reacts with these compounds so as to ionize the gases to be analyzed.
It proves that analyses carried out by either of these methods may be altered by the presence of undesired compounds. Thus, for example the detection of chlorinated organic compositions may be altered for samples containing high concentrations of salt spray.
More particularly, the aim of the invention is to eliminate these drawbacks by using a high-performance analyzer able to be produced in the form of a portable and automatic device so as to conduct practically instantaneous analyses in situ.
According to the invention, the analyzer includes a tubular burner comprising at least one continuous intake nozzle for a gas sample to be analyzed, and coaxial to said nozzle:
a first tubular sleeve with a bottom traversed by said nozzle, this sleeve successively defining with said nozzle an annular chamber for admitting a combustive gas, such as hydrogen, derived from a source, then a first combustion chamber extending beyond the end of the nozzle,
a second tubular sleeve with a bottom through which the nozzle traverses, said second sleeve successively defining with the first sleeve an annular chamber for admitting an oxidant gas such as air, and a second combustion chamber extending beyond the end of the first tubular sleeve, said second tubular sleeve including an opening for evacuating gases originating from combustion,
a pair of electrodes associated with a circuit measuring the conductivity of a combustion zone located in the second combustion chamber,
a focusing optic coaxial to said sleeves for focusing the image of the flame generated in at least the first combustion chamber on the input orifice of a spectrophotometric mounting.
Said apparatus includes in addition a processor able to process data delivered by the measurement circuit and/or the spectrophotometric mounting so as to deduce therefrom the concentration in the searched elements of the sample.
Advantageously, said pair of electrodes could include an annular electrode rendered integral with the second tubular sleeve so as to encircle at least partially the second combustion chamber : in this case, the first electrode could consist of the first tubular sleeve.
Of course, the first tubular sleeve could include at least at the level of its external surface a coating made of a suitable material able to emit a reactive gas under the effect of heat generated in the first combustion chamber. This coating could for example be made of indium so as to be able to detect chlorine.
In this case, the burner could include a third tubular coaxial sleeve defining with the first sleeve an annular chamber opening into the second combustion chamber and used for admitting a hydrogen current derived from said source. To this effect, this annular chamber is connected to this source via an intake circuit controlled by a valve.
By means of these dispositions, by combining the data supplied by these two analysis means (flame spectrophotometry/ionization), it is possible to significantly differentiate the number of searched elements or substances and especially resolve the problems of overlapping or masking of characteristic spectral lines of elements searched by others, even noise. Thus, it is possible to solve the problems of masking of hydrocarbonated chlorinated compounds by salt spray. In fact, it possible to determine the total concentration of sodium chloride by noting the concentration of sodium by means of spectrophotometry. To then obtain the concentration of the other chlorinated compounds, this sodium concentration is deducted from the total concentration of chlorine determined by means of the reactive gas emitted by the coating of the first tubular sleeve. The concentration of chlorinated organic compounds may then be determined from the data detected by the detection circuit FID (which determines the concentration of hydrocarbonated compounds).
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Bleuse Patrick
Clausin Pierre
Guene Gilles
Lancelin Henri
Drucker William A.
Proengin S.A.
Sines Brian
Warden Jill
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