JPH0587737A - Flame light intensity detector - Google Patents

Abstract

PURPOSE:To prevent the sensitivity decline of this detector by heating a heater provided at a glass window in an interlocking way with an igniting signal so as to prevent the condensation of steam on the glass of the window. CONSTITUTION:When an ignition coil 2 is heated by issuing an igniting signal and, at the same time, hydrogen (H2) is fired by injecting the hydrogen, a sample, a carrier gas, and air into a cavity 1, an S2 or HPO atomic group is generated from a sulfide or phosphide compound. The atomic group is thermally excited and radiates a peculiar molecular spectrum. The spectral light is led to a light intensity detecting section 3 through window glass 4 and converted into an electric signal. When the hydrogen is fired, steam is generated, but the generated amount of the steam becomes constant after the amount abruptly increases in the initial stage of the firing. On the other hand, a control, section 7 refers to a temperature signal from a temperature sensor 6 in an interlocking way with the igniting signal and, when the temperature of the glass 4 is lower than a prescribed value, prevents the sensitivity decline of a hydrogen flame ion detector due to the condensation of the steam on the glass 4 by abruptly raising the temperature of the glass 4 by driving heaters 5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to process gas chromatographs, and more particularly to flame photometric detectors sensitive to sulfur-containing compounds.

[0002]

2. Description of the Related Art In gas chromatographs, many detectors utilizing various properties of substances to be measured have been proposed so far. Typical examples include a thermal conductivity detector (hereinafter referred to as TCD) and a hydrogen flame ionization detector (hereinafter referred to as FID).

TCD has relatively low sensitivity, but has a characteristic of responding regardless of whether it is an inorganic material or an organic material. or,
FID does not respond to inorganic substances, but has an order of magnitude higher responsiveness than TCD.

However, for example, when it is desired to quantify nitrogen-containing compounds and sulfur-containing compounds in gasoline from the viewpoint of harmful substances, since there are many kinds of hydrocarbons in gasoline and the content is high, FID is used. However, many of the target components are hidden in large peaks of many hydrocarbons and cannot be quantified. For this reason, a selective detector is used which has a high response only to the target component and hardly responds to other components.

Therefore, a flame photometric detector (FPD) is used for selective detection of sulfur or phosphorus. This FP
When D mixes hydrogen (H ₂ ), sample, carrier gas and air in the cavity and burns the hydrogen in this cavity, atomic groups such as S 2 from sulfur compounds and HPO from phosphorus compounds are generated. When they are thermally excited, each emits a unique molecular emission spectrum. The former spectrum has the maximum emission intensity at 384 nm and 394 nm, and the latter spectrum has the maximum emission intensity at 528 nm.Therefore, by continuously measuring the change in the spectral intensity at these wavelengths using an interference filter, only the sulfur and phosphorus compounds can be detected. It is possible to draw a selective chromatograph consisting of the peaks.

This FPD has a measurement component (H
₂ S, COS, etc.), it is often used at a relatively low temperature of 50 to 80 ° C.

[0007]

However, when the cavity of the FPD is sufficiently heated, water (water vapor) generated by the combustion of hydrogen does not condense, but when the cavity is ignited from the extinguished state. In the case of FPD, since heat generation of the FPD itself has not progressed, water vapor may condense and water may adhere to the wall surface inside the FPD.

In particular, when water adheres to the glass window which transmits light to the light intensity detecting portion, there is a problem that the amount of light decreases and the sensitivity of the FPD decreases. The present invention has been made in view of the above problems, and an object thereof is to provide a flame photometric detector that can prevent a decrease in the sensitivity of an FPD.

[0009]

DISCLOSURE OF THE INVENTION The present invention which solves the above-mentioned problems is, in a flame photometric detector mounted on a process gas chromatograph, a glass window which is disposed on the wall surface of a cavity and transmits light to the photometric detector. A heating member is provided in the above, and the heating member is operated in conjunction with the ignition signal.

[0010]

In the flame photometric detector of the present invention, the heating member provided in the glass window operates in conjunction with the ignition signal,
Prevents water vapor from condensing on the window glass.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is a diagram illustrating a time chart in FIG.

First, the configuration of this embodiment will be described with reference to FIG. In the figure, 1 is a cavity for mixing hydrogen (H ₂ ), a sample, a carrier gas and air. An ignition coil 2 for hydrogen combustion is provided in the cavity 1. Further, on the wall surface of the cavity 1, there is provided a window glass 4 for transmitting the hydrogen light to the light intensity detecting section 3.

The window glass 4 has a heater 5 as a heating member.
Is provided. Further, the window glass 4 is provided with a temperature sensor 6 that detects the temperature of the window glass 4. Reference numeral 7 is a control unit that takes in an ignition signal to the ignition coil 2 and a temperature signal from the temperature sensor 6 and drives the heater 5.

Next, the operation of the above configuration will be described. First,
When the ignition signal shown in FIG. 2A is issued, the ignition coil 2 is heated. Next, hydrogen (H ₂ ), a sample, a carrier gas and air are introduced into the cavity 1, hydrogen is burned, S ₂ is generated from the sulfide compound, and HPO atomic groups are generated from the phosphorus compound. Being excited,
Each emits a unique molecular emission spectrum. This spectrum light reaches the light intensity detection unit 3 through the window glass 4 and is converted into an electric signal there.

At this time, the amount of water generated in the cavity 1 due to the combustion of hydrogen becomes constant after a predetermined time as shown in FIG. 2 (b). On the other hand, when the ignition signal to the ignition coil 2 is issued, the control unit 7 refers to the temperature signal from the temperature sensor 6, and when the temperature of the window glass 4 is below the specified temperature, the control unit 7 turns on the heater 5. The window glass 4 is driven to heat the window glass 4 as shown by the broken line in FIG. 2C, and the temperature of the window glass 4 is rapidly raised to a predetermined temperature.

According to the above construction, as shown by the broken line (with heating of the heater 5) and the solid line (without heating of the heater 5) in FIG. By rapidly raising the temperature of 4 to a predetermined temperature, it is possible to greatly reduce the condensation of water vapor in the cavity 1 on the window glass 4, and to prevent the sensitivity of the FPD from lowering.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the temperature sensor 6 is provided on the window glass 4, and the controller 7 drives the heater 5 according to the temperature of the window glass 4 output by the temperature sensor 6 to keep the temperature of the window glass 4 constant. However, when the ignition signal is turned on, the heater 5 is driven for a certain period of time so that the window glass 4 is rapidly heated. May be.

[0018]

As described above, according to the present invention, the FP
It is possible to realize a flame photometric detector that can prevent a decrease in the sensitivity of D.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a time chart in FIG.

[Explanation of symbols]

 1 Cavity 3 Light intensity detector 4 Window glass 5 Heater

Claims (1)

[Claims] 1. A flame photometric detector mounted on a process gas chromatograph, the photometric detector (3) being disposed on a wall surface of a cavity (1).
A flame photometric detector characterized in that a heating member (5) is provided on a glass window (4) which transmits light to the light, and the heating member (5) is operated in conjunction with an ignition signal.