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EP-4153973-B1 - FLAME PHOTOMETRIC DETECTOR

EP4153973B1EP 4153973 B1EP4153973 B1EP 4153973B1EP-4153973-B1

Inventors

  • ZHANG, EDWARD
  • WATKINS, WILLIS
  • BLACK, Steven S.

Dates

Publication Date
20260506
Application Date
20210520

Claims (9)

  1. A flame photometric detector (500) for a process gas chromatograph, the flame photometric detector comprising: a combustion chamber body (510) defining a combustion chamber (560) therein; a sample inlet tube (532) configured to introduce a process gas sample into the combustion chamber; an ignitor (551) configured to initiate combustion within the combustion chamber; a thermocouple assembly (553) configured to provide an indication of temperature within the combustion chamber; characterised by further comprising: a gas mixer (518) threadably disposed within the combustion chamber body, and wherein rotation of the gas mixer affects the adjustable position of the end (532E) of the sample inlet tube relative to the combustion chamber.
  2. The flame photometric detector of claim 1, wherein the combustion chamber has a substantially half round shape.
  3. The flame photometric detector of claim 1, wherein the combustion chamber has a substantially flat bottom (592).
  4. The flame photometric detector of claim 1, wherein the ignitor and the thermocouple assembly are mounted to a single tube (552) that extends into the combustion chamber.
  5. The flame photometric detector of claim 1, wherein the adjustable position of the end of the sample inlet tube is pre-optimized for detector response.
  6. The flame photometric detector of claim 1, wherein the ignitor and the thermocouple assembly enter the combustion chamber of the flame photometric detector via a single aperture.
  7. The flame photometric detector of claim 1, wherein the combustion chamber has a flat surface proximate an end of the sample inlet tube.
  8. The flame photometric detector of claim 4, wherein the single tube is a ceramic tube.
  9. The flame photometric detector of claim 8, wherein the ceramic tube includes at least four bores (552A - 552D) extending axially therethrough.

Description

BACKGROUND Gas chromatography is the separation of a mixture of chemical compounds due to their migration rates through a chromatographic column. This separates the compounds based on differences in boiling points, polarity, or molecular size. The separated compounds then flow across a suitable detector, such as a flame photometric detector (FPD), that determines the concentration and/or presence of each compound represented in the overall sample. Knowing the concentration or presence of the individual compounds makes it possible to calculate certain physical properties such as BTU or a specific gravity using industry-standard equations. In operation, a sample is often injected in to a chromatographic column filled with a packing material. Typically, the packing material is referred to as a "stationary phase" as it remains fixed within the column. A supply of inert carrier gas is then provided to the column in order to force the injected sample through the stationary phase. The inert gas is referred to as the "mobile phase" since it transits the column. As the mobile phase pushes the sample through the column, various forces cause the constituents of the sample to separate. For example, heavier components move more slowly through the column relative to the lighter components. The separated components, in turn, exit the column in a process called elution. The resulting components are then fed into a detector that responds to some physical trait of the eluting components. One type of detector is known as a flame photometric detector. The flame photometric detector uses a photo multiplier tube to detect spectral lines of the compounds as they are burned in a flame. Compounds eluting off the column are carried into a generally hydrogen fueled flame which excites specific elements in the molecules, and the excited elements (P, S, halogens, some metals) emit light of specific characteristic wavelengths. The emitted light is filtered and detected by the photo multiplier tube. In particular, phosphorous emission is around 510-536 nm and sulfur emission is around 394 nm. US 2015/015885 is considered as the closest prior art and presents a flame photometric detector according to the preamble of claim 1. US 2006/213875 presents further related prior art. SUMMARY A flame photometric detector for a process gas chromatograph is provided according to claim 1. The flame photometric detector includes a combustion chamber body defining a combustion chamber therein. A sample inlet tube is configured to introduce a process gas sample into the combustion chamber. An ignitor is configured to initiate combustion within the combustion chamber. A thermocouple assembly is configured to provide an indication of temperature within the combustion chamber. The flame photometric detector further comprises a gas mixer threadably disposed within the combustion chamber body, and wherein rotation of the gas mixer affects the adjustable position of the end of the sample inlet tube relative to the combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of a process gas chromatograph employing a known flame photometric detector side-cart solution in accordance with the prior art.FIG. 2 is a diagrammatic view of a process gas chromatograph with which embodiments of the present invention may be used.FIG. 3 is a diagrammatic system view of a gas chromatograph in accordance with an embodiment of the present invention.FIG. 4 is an enlarged view of the prior art flame photometric detectors used in side-cart solutions.FIG. 5 is a diagrammatic perspective view of a gas chromatograph and flame photometric detector in accordance with an embodiment of the present invention.FIGS. 6A and 6B are cross-sectional views of a prior art flame photometric detector.FIGS. 7A and 7B are perspective and side elevation views, respectively, of a micro flame photometric detector in accordance with an embodiment of the present invention.FIGS. 7C - 7F are various diagrammatic cutaway and cross-sectional views of a micro flame photometric detector in accordance with an embodiment of the present invention.FIG. 8 is a perspective view of a combination thermocouple/ignitor assembly for a micro flame photometric detector in accordance with an embodiment of the present invention.FIG. 9 is an exploded view of a combination thermocouple/ignitor assembly for a micro flame photometric detector in accordance with an embodiment of the present invention.FIG. 10 is a cross sectional view of a sample tube assembly of a micro flame photometric detector is accordance with an embodiment of the present invention.FIG. 11 is a gas mixer of a micro flame photometric detector in accordance with embodiments of the present invention.FIG. 12 is a cross-sectional view of a micro flame photometric detector in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS A conventional flame photometric detector burner generally co