阅读说明：本技术 火焰光度检测仪 (Flame luminosity detector ) 是由 爱德华·张 威利斯·沃特金斯 史蒂文·S·布莱克 于 2021-05-21 设计创作，主要内容包括：提供了一种用于过程气相色谱仪的火焰光度检测仪。该火焰光度检测仪包括燃烧室本体,该燃烧室本体限定在该燃烧室本体中的燃烧室。样品入口管被配置为将过程气体样品引入到燃烧室中。点火器被配置为在燃烧室内引发燃烧。热电偶组件被配置为提供燃烧室内的温度的指示。样品管具有相对于燃烧室能够调节的端部。(A flame photometric detector for a process gas chromatograph is provided. The flame photometric detector includes a combustion chamber body defining a combustion chamber therein. The sample inlet tube is configured to introduce a process gas sample into the combustion chamber. The igniter is configured to initiate combustion within the combustion chamber. The thermocouple assembly is configured to provide an indication of a temperature within the combustion chamber. The sample tube has an end portion adjustable relative to the combustion chamber.)

1. A flame photometric instrument for a process gas chromatograph, the flame photometric instrument comprising:

a combustor body defining a combustion chamber therein;

a sample inlet tube configured to introduce a process gas sample into the combustion chamber;

an igniter configured to initiate combustion within the combustion chamber;

a thermocouple assembly configured to provide an indication of a temperature within the combustion chamber; and

wherein the sample inlet tube has an end that is adjustable relative to the combustion chamber.

2. The flame photometric instrument of claim 1, further comprising a gas mixer threadably disposed within the combustion chamber body, and wherein rotation of the gas mixer effects an adjustable position of the end of the sample tube relative to the combustion chamber.

3. A flame photometric instrument according to claim 1 wherein the combustion chamber has a generally semi-circular shape.

4. A flame photometric instrument according to claim 1 wherein the combustion chamber has a substantially flat bottom.

5. The flame photometric instrument of claim 1, wherein the igniter and the thermocouple assembly are mounted to a single tube that extends into the combustion chamber.

6. 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.

7. A process gas chromatograph comprising:

a temperature controlled furnace;

at least one chromatography column disposed within the temperature-controlled furnace and configured to receive a sample of a process gas;

a flame photometric detector operably coupled to the at least one chromatography column and disposed within the temperature controlled furnace, the flame photometric detector configured to combust a sample of the process gas and provide an indication of a flame combusting the sample; and

a photomultiplier tube assembly coupled to the flame photometric detector and configured to receive an indication from the flame photometric detector and provide a signal indicative of a wavelength of the flame.

8. The process gas chromatograph of claim 7, wherein the flame photometric detector is coupled to the photomultiplier tube assembly by a fiber optic cable.

9. The process gas chromatograph of claim 7, wherein the flame photometric detector includes an igniter and a thermocouple assembly, and wherein the igniter and the thermocouple assembly enter a combustion chamber of the flame photometric detector via a single orifice.

10. The process gas chromatograph of claim 9, wherein the igniter and the thermocouple assembly are mounted to a single tube that extends into the combustion chamber.

11. The process gas chromatograph of claim 10, wherein the single tube is made of ceramic.

12. The process gas chromatograph of claim 7, wherein the flame photometric detector includes an internal combustion exhaust channel.

13. The process gas chromatograph of claim 7, further comprising a sample tube configured to receive the sample and deliver the sample to the combustion chamber, the sample tube having an end that is adjustable relative to the combustion chamber.

14. The process gas chromatograph of claim 7, wherein the flame photometric detector includes a combustion chamber having a substantially semi-circular shape.

15. The process gas chromatograph of claim 14, wherein the combustion chamber has a substantially flat bottom.

16. A flame photometric instrument for a process gas chromatograph, the flame photometric instrument comprising:

a combustor body defining a combustion chamber therein;

a sample inlet tube configured to introduce a process gas sample into the combustion chamber;

an igniter configured to initiate combustion within the combustion chamber;

a thermocouple assembly configured to provide an indication of a temperature within the combustion chamber; and

wherein the combustion chamber has a semicircular shape.

17. The flame photometric instrument of claim 16, wherein the semi-circular combustion chamber has a flat surface proximate to an end of the sample inlet tube.

18. A flame photometric instrument for a process gas chromatograph, the flame photometric instrument comprising:

a combustor body defining a combustion chamber therein;

a sample inlet tube configured to introduce a process gas sample into the combustion chamber;

an igniter configured to initiate combustion within the combustion chamber;

a thermocouple assembly configured to provide an indication of a temperature within the combustion chamber; and

wherein the igniter and the thermocouple assembly are mounted to a single tube that extends into the combustion chamber.

19. A flame photometric instrument according to claim 18 wherein the single tube is a ceramic tube.

20. The flame photometric instrument of claim 19, wherein the ceramic tube comprises at least four holes extending axially through the ceramic tube.

Technical Field

The invention relates to a flame photometric detector.

Background

Gas chromatography is the separation of a mixture of chemical compounds due to their rate of migration through a chromatographic column. This separates compounds based on differences in boiling point, polarity, or molecular size. The separated compounds then flow through a suitable detector, such as a Flame Photometric Detector (FPD), which determines the presence and/or concentration of each compound represented in the entire sample. Knowing the concentration or presence of various compounds allows the use of industry standard equations to calculate certain physical properties, such as BTU or specific gravity.

In operation, a sample is typically injected into a chromatography column filled with packing material. Typically, the packing material is referred to as the "stationary phase" because it remains fixed within the chromatography column. A supply of inert carrier gas is then provided to the chromatographic column to force the injected sample through the stationary phase. The inert gas is referred to as the "mobile phase" as it is transported through the column.

As the mobile phase pushes the sample through the chromatography column, various forces cause components of the sample to separate. For example, heavier components move more slowly through the column than lighter components. The separated components, in turn, exit the column by a process known as elution. The resulting fraction is then fed into a detector that responds to certain physical properties of the eluted fraction.

One type of detector is known as a flame photometric detector. Flame photometers use photomultiplier tubes to detect spectral lines of a compound as it burns in a flame. The compounds eluted from the column are carried into a flame, usually fueled by hydrogen, which excites specific elements in the molecule, and the excited elements (P, S, halogens, some metals) emit light with specific characteristic wavelengths. The emitted light is filtered and detected by a photomultiplier tube. In particular, the phosphor emission is about 510nm to 536nm, while the sulfur emission is about 394 nm.

Disclosure of Invention

A flame photometric detector for a process gas chromatograph is provided. The flame photometric detector includes a combustion chamber body defining a combustion chamber therein. The sample inlet tube is configured to introduce a process gas sample into the combustion chamber. The igniter is configured to initiate combustion within the combustion chamber. The thermocouple assembly is configured to provide an indication of a temperature within the combustion chamber. The sample tube has an end portion adjustable relative to the combustion chamber.

Drawings

Fig. 1 is a schematic diagram of a process gas chromatograph employing a known flame photometric detector side cart solution according to the prior art.

Fig. 2 is a schematic diagram of a process gas chromatograph that may be used with embodiments of the present invention.

Fig. 3 is a system schematic of a gas chromatograph according to an embodiment of the present invention.

FIG. 4 is an enlarged view of a prior art flame photometric detector used in a side cart solution.

FIG. 5 is a schematic perspective view of a gas chromatograph and flame photometric detector according to an embodiment of the present invention.

Fig. 6A and 6B are cross-sectional views of a prior art flame photometric detector.

FIGS. 7A and 7B are perspective and side views, respectively, of a micro flame photometric detector according to an embodiment of the present invention.

FIGS. 7C-7F are various schematic cross-sectional and cross-sectional views of a micro flame photometric detector according to embodiments of the present invention.

FIG. 8 is a perspective view of a combined thermocouple/igniter assembly for a micro flame photometric detector according to an embodiment of the present invention.

FIG. 9 is an exploded view of a combined thermocouple/igniter assembly for a micro flame photometric detector according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view of a sample tube assembly of a micro flame photometric detector according to an embodiment of the present invention.

FIG. 11 is a gas mixer of a micro flame photometric detector according to an embodiment of the present invention.

FIG. 12 is a cross-sectional view of a micro flame photometric detector according to an embodiment of the present invention.

Detailed Description

Conventional flame photometric detector burners typically include: a flame chamber, an external pendant top exhaust path, an igniter, a thermocouple, and a gas mixer. In some relatively small footprint applications (bubble application), such as explosion-proof gas chromatography applications, it may be helpful to minimize the physical size of the flame photometer to fit within a dedicated temperature-controlled oven. A micro-burner for a Flame Photometric Detector (FPD) may be provided that includes an internal exhaust path and an integrated igniter/thermocouple.

The micro-flame photometric detector can be installed in such small footprint applications according to the embodiments described below. In some examples described below, the micro flame photometric detector may include a generally semi-circular flame chamber having a reduced size relative to previous designs. Further, in some examples, an integrated sample tube is used to position the end of the sample tip at a precise location of the mixed gas stream in order to minimize the effort for tip adjustment and maximize the response of the micro flame photometric detector.

Fig. 1 is a schematic diagram of a process gas chromatograph 20 employing a known flame photometric detector side cart (side-cart) solution according to the prior art. The side cart 10 is shown proximate to the process gas chromatograph 20 and coupled to the process gas chromatograph 20 by a plurality of lines. This side cart solution is typically used because the flame photometer of the side cart 10 cannot physically fit within the space limited explosion proof oven 22 of the process gas chromatograph 20.

Before describing the flame photometer in detail, it is useful to first generally describe the process gas chromatograph with which the flame photometer is used.

Fig. 2 is a schematic diagram of a process gas chromatograph that may be used with embodiments of the present invention. While fig. 1 shows a gas chromatograph 100 of type 700XA available from Rosemount Inc (Emerson Automation Solutions), the methods and embodiments provided herein may be used with other exemplary gas analyzers. This may include a model 1500XA process gas chromatograph and a model 570 gas chromatograph available from rossmont corporation, as well as various other types and models of gas chromatographs. Additionally, it is contemplated that a variety of other devices besides gas chromatographs may be used with embodiments of the present invention. As shown in fig. 2, process gas chromatograph 100 includes a user interface 102 having a display and one or more user input mechanisms 104 for user interface 102. In addition, process gas chromatograph 100 includes a temperature controlled oven 106. The components within the furnace 106 can be maintained at a very precisely controlled temperature to facilitate the analysis process.

Fig. 3 is a system schematic of a gas chromatograph according to an embodiment of the present invention. While one example of gas chromatograph 200 will now be provided, it should be understood that gas chromatograph 200 may take a variety of other forms and configurations. For example, it should be understood that gas chromatograph 200 may have other configurations for columns, valves, detectors, and the like. However, in this example, gas chromatograph 200 illustratively includes a carrier gas inlet 202, a sample inlet 204, a sample exhaust 206, and a measurement exhaust 208. In operation, a carrier gas is provided to a flow panel (flow panel)210, where it travels through a conditioner 212 and a dryer 214 before entering a temperature controlled analyzer furnace 216 and traveling through a carrier gas preheater 218.

During a measurement, a sample gas enters chromatograph 200 via sample inlet 204 and enters analyzer oven 216. The sample gas (during measurement) or calibration gas (during calibration) and carrier gas ultimately enter a plurality of pneumatically controlled multiport selector valves 260 to selectively flow various volumes of sample and/or carrier gas through the various chromatography columns 222 in accordance with known gas chromatography techniques. Each of the pneumatically controlled multi-port selector valves 260 is fluidly coupled to a respective solenoid 224, the solenoid 224 receiving its control signal from the controller 226. In addition, the controller 226 may be coupled to one or more temperature sensors within the oven 216 and one or more heaters thermally coupled to the oven 216 to provide temperature control for the oven 216. However, it is also contemplated that a separate thermal control system from controller 226 may be used.

Additionally, as shown in FIG. 3, each pneumatically controlled multiport selector valve 260 has a pair of states. In the first state, the fluid connection of each valve 260 is shown in solid lines. In the second state, the fluid connection of each valve 260 is shown in phantom. The controller 226 is operatively coupled to a detector 228, the detector 228 being a flame photometric detector, as will be described in more detail below. Thus, controller 226 is able to fully control flow through gas chromatograph 200 by means of control solenoid 224. In addition, the controller 226 can determine the response of the detector 228 in order to detect or otherwise characterize various species in the sample gas. In some embodiments, controller 226 reads the analog signal from control module 34 (shown in FIG. 4). In addition, the controller 226 can characterize, calculate, and identify peaks in the chromatogram. In this manner, the controller 226 can selectively introduce a sample into the column, reverse the flow of gas through the column, and direct the reversed flow of gas through the detector for a selected amount of time to observe and/or record the detector response over time. This provides a chromatographic analysis for the sample.

FIG. 4 is an enlarged view of a prior art flame photometric detector used in a side cart solution. As shown, the flame photometric detector burner 30 is positioned adjacent to a photomultiplier tube module 32. The control module 34 is disposed above the photomultiplier tube module 32 and controls the burner 30 and photomultiplier tube module 32. In an example, the control module 34 processes and amplifies the response signal from the photomultiplier tube module 32 and provides the response signal to a suitable processing device, such as a controller 226.

According to embodiments described herein, as shown in FIG. 5, a micro-flame photometric detector is provided that rearranges the three major components of the flame photometric detector by disassembling the flame photometric detector burner and the photomultiplier tube module, and incorporates a control module and photomultiplier tube module. As can be seen, the miniature flame photometric detector 300 is coupled to a photomultiplier tube and control module 302 via a fiber optic cable 304. According to one embodiment, the micro flame photometric detector 300 can be completely assembled within the volume of the temperature controlled oven 22 of the process gas chromatograph. Accordingly, the entire side cart heretofore may now be substantially assembled within the gas chromatograph housing.

Some of the structural changes that contribute to these significant changes are shown with respect to fig. 5 relative to fig. 4, and are facilitated by changes in the design of the flame photometric detector itself.

Fig. 6A and 6B are cross-sectional views of a prior art flame photometric detector. Fig. 6B is a cross-sectional view taken along line B-B in fig. 6A. As shown in fig. 6A and 6B, a typical flame photometric instrument burner 400 of a gas chromatograph is arranged as shown. The detector 400 has a mounting portion 421, the mounting portion 421 for coupling to optics and a photomultiplier tube. During operation, air enters through fitting 417 and hydrogen enters through fitting 415. Column effluent (sample) gas is provided via sample tube 423. The air and hydrogen are mixed at gas mixer 414 and enter combustor 412. The igniter 419 ignites the flame and the gas is combusted within the combustion chamber 412. The thermocouple 413 monitors the state of the flame, and the burned gas is discharged through the exhaust path 410 of the fitting 411. Light having a specific wavelength is generated from the flame and detected. The response of the flame photometric detector is very sensitive to the end position 418 of the sample tube 423 relative to the gas mixer 414. The response of the flame photometer can be maximized by moving the sample tube 423 up and down with the same gas mixing ratio. For most applications (e.g., detection of sulfur components in natural gas), it is necessary to properly vent the combusted gases from the flame photometric detector burner for safety reasons.

FIGS. 7A and 7B are perspective and side views, respectively, of a micro flame photometric detector according to an embodiment of the present invention. To efficiently route the exhaust gases from the combustion flame, the internal exhaust path within the micro flame photometric detector 500 reroutes the exhaust fitting to the exact location required to minimize the physical size of the burner and simplify the piping. These internal flow paths of embodiments of the present invention are shown in more detail in fig. 7C, 7D, and 7E. The micro flame photometric detector 500 includes a combustion chamber body 510, a connector 512, and a cover 511.

For clarity of explanation, fig. 7C is a cross-sectional view taken along line a-a in fig. 7B. Similarly, fig. 7D is a cross-sectional view taken along line B-B in fig. 7B. FIG. 7E is a partial cross-sectional view of the micro flame photometric detector. Fig. 7F is an enlarged cross-sectional view taken from circle "C" in fig. 7D.

Air typically enters the burner through fitting 516, hydrogen enters the burner through fitting 517, and sample gas from the column enters the burner through fitting 530. The air and hydrogen are mixed at gas mixer 518 and combusted in combustor 560. Then, the burned gas passes through the exhaust paths 540A and 540B of the combustion chamber body 510, the paths 541A, 541B, and 541C of the connector 512, and then is discharged through the path 542 of the fitting 514. The cross-drilled holes for the exhaust path may simply be plugged with standard steel balls 513A and 513B to simplify and minimize the physical size of the combustor. However, the vent path may be plugged in any suitable manner.

FIG. 8 is a perspective view of a combined thermocouple/igniter assembly for a micro flame photometric detector according to an embodiment of the present invention. In the configuration shown in fig. 8, the igniter and thermocouple required for the flame photometric detector are integrated. The integrated structure 550 requires only a single entry into the combustion chamber 560 shown in fig. 7D and 7E.

FIG. 9 is an exploded view of a combined thermocouple/igniter assembly for a micro flame photometric detector according to an embodiment of the present invention. The integrated temperature sensing igniter 550 is typically constructed of a high temperature insulating material, such as a ceramic tube 552 having four holes extending axially therethrough. The igniter 551 and thermocouple 553 extend through two of the holes, while the leads 551A and 551B of the igniter 551 extend through the holes 552A and 552B of the ceramic tube 552. Leads 553A and 553B pass through the holes 552C and 552D of the ceramic tube 552. Leads 551A, 551B, 553A, and 553B are operatively coupled to controller 226 or other suitable circuitry to control ignition and detect temperature within combustion chamber 560. The four-hole ceramic tube 552 provides cost-effective insulation between the leads of both the igniter 551 and the thermocouple 553.

The response of the flame photometer is very sensitive to the relative position D (shown in FIG. 7F) between the end of the sample tube 532 and the gas mixer 518. The response of the flame photometer may be altered by adjusting the end position 532E of the sample tube 532. Once the response of the flame photometric detector is maximized, the optimal position "D" is found.

As shown in fig. 7F and 10-12, the dimension H1 may be calculated as H1 ═ D + H2+ H3, as shown in fig. 7D. Dimension H1 is shown in fig. 10 with respect to fitting 531. The sample tube 532 is typically pressed into a modified fitting 531, allowing the dimension H1 to be easily mechanically controlled. In other words, as shown in fig. 10, the optimal position "D" can be achieved by appropriately controlling the dimension H1 of the sample tube assembly.

Dimension H2 is shown in fig. 11 with respect to gas mixer 518. The position of the gas mixer 518 within the combustion chamber body 510 is determined by shoulder "a" (shown in fig. 11) and stop "B" (shown in fig. 12) of the combustion chamber body 510. The gas mixer 518 is secured in the combustion chamber body 510 by external threads 582 that engage internal threads in the combustion chamber body 510.

Dimension H3 is shown in fig. 12 with respect to the combustor body 510. Thus, the optimal position D may be achieved by controlling H1 of the sample tube assembly, H2 of the gas mixer 518, and H3 of the combustion chamber body 510 during manufacturing. This means that the position can be optimized in advance by the manufacturer and therefore does not require any additional optimization by the user. As used herein, "pre-optimization" refers to optimization of position D by the manufacturer or during manufacture of the system. This is in contrast to prior designs such as that shown with respect to FIG. 6B, which required user optimization of each system produced by the user. Repeatability of the response between flame photometers is well controlled and the effort to set flame photometers is significantly reduced.

As shown in FIG. 12, the combustion chamber 560 generally includes a curved upper portion 590, the curved upper portion 590 meeting a flat lower portion 592 at a rounded portion 594. This semi-circular shape of the combustion chamber 560 is believed to help minimize the physical size of the FPD burner.

While the embodiments described thus far generally provide a miniature flame photometric detector that can be installed within a temperature controlled oven of a process gas chromatograph, it is believed that at least some embodiments described herein also facilitate easier and less costly manufacturing. For example, as shown in fig. 7D, 7E, and 7F, the combustor body 510 and the gas mixer 518 are designed such that the gas mixer 518 can be assembled from the bottom up.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.