JPS6222425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an apparatus for efficiently measuring the concentration of non-methane organic compounds using a flame ionization detector (FID).

Devices that measure the concentration of hydrocarbons in the atmosphere using flame ionization detectors have been known for some time, but it is difficult to accurately measure the concentration of non-methane hydrocarbons, and the measurement targets are also limited. It was limited to ambient air containing trace amounts of hydrocarbons. However, in recent years, it has become clear that the occurrence of photochemical smog is caused by non-methane hydrocarbons and their derivatives present in the atmosphere, and there is an urgent need to be able to measure their concentrations with precision and to ensure the suppression of photochemical oxidants. It has been said that Furthermore, the Environment Agency has made it mandatory to measure the concentration of non-methane hydrocarbons not only in the ambient air, but also at sources such as gas stations and various manufacturing plants.
Policies are being advanced to implement more proactive pollution control.

However, in such sources, unlike in the ambient air, the concentration of hydrocarbons, etc.
The range ranges from ppm to several percent or even tens of percent, and the measurement targets are not just hydrocarbons, but also alcohols, aldehydes, for which a response proportional to the number of carbon atoms cannot be obtained with a flame ionization detector,
It includes various hydrocarbon derivatives such as ketones, halides, and phenols. Therefore, since this type of measurement is not possible with a flame ionization detector, the sample was collected separately into low-boiling point compounds and high-boiling point compounds, and CO, CO ₂ and CH ₄ were separated from the low-boiling point compounds using a column. , oxidizes the remaining compounds and converts them into CO ₂ and H ₂ O.
A method for measuring CO ₂ using a non-dispersive infrared analyzer (NDIR) has been developed, but this method not only requires expensive equipment, but also has the drawbacks of poor workability and difficulty in obtaining stable results.

The present invention eliminates these drawbacks and stabilizes the concentration of non-methane organic compounds, not only for hydrocarbons but also for all organic compounds from various manufacturing plants, with improved workability. To provide a simple device that can perform measurements.

The device of the present invention can reduce CO, CO ₂ and CH ₄ in the sample.
a first column or cooling trap for separating non _- methane organic compounds from non-methane organic compounds; an oxidation furnace for oxidizing the non-methane organic compounds discharged from the first column or _cooling trap;
A second column or cooling trap to separate from O ₂ , a flow switching device for transferring CO ₂ retained in the second column or cooling trap to the reduction reactor, and the second column or cooling The reduction furnace for reducing CO ₂ discharged from the trap to CH ₄ , and the CO, CO ₂ and CH ₄ in the sample flowing out from the first column or the cooling trap and the CH ₄ flowing out from the reduction furnace. A detector, such as a flame ionization detector, is arranged to pass through the detector.

In addition, it is preferable that CO, CO ₂ and CH ₄ in the sample flowing out from the first column or the cooling trap also pass through the reduction furnace and reach the hydrogen flame ionization detector. in the sample
It is easy to determine when to switch the flow path after CO, CO ₂ and CH ₄ have flowed out, and it is also possible to measure the concentration ratio of CH ₄ to CO and CO ₂ .

The present invention will be explained according to an example shown in the drawings.
First, the sample is sent from the sample valve 1 to the first column or cooling trap 2 together with a carrier gas A such as nitrogen, and only CO, CO ₂ and CH ₄ are sent to the flame ionization detector 6 through the flow path 7, and their chromatograms are After confirming this, the flow switching device is activated to backflush the first column or cooling trap 2, for example, and send the retained non-methane organic compound to the oxidation furnace 3.

In the oxidation furnace 3, for example, oxygen a is added at a rate of 5 to 20%.
supply and oxidize non-methane organic compounds that have been charred under heating conditions of 400-800℃, all with _CO2
Convert to _H2O . Then this CO ₂ and H ₂ O are ₂
is sent to the second column or cooling trap 4, where only CO ₂ and H ₂ O are retained and O ₂
After that, the CO ₂ retained in the second column and the cooling trap 4 is sent to the reduction furnace 5 by operating the flow path switching device, and the hydrogen b
is reduced to CH ₄ , and the concentration of this CH ₄ is measured through a hydrogen flame ionization detector 6 . In the second column or cooling trap 4 CO ₂ is replaced with H ₂ O
Preferably, it is also separated from

In the present invention, the non-methane organic compound is completely oxidized in the oxidation furnace 3, and the resulting _CO2 is transferred to the reduction furnace 5.
Since the hydrogen flame ionization detector 6 works effectively to measure the concentration of CH ₄ , stable and accurate analysis is possible regardless of the type and concentration of the organic compound in the sample. Furthermore, it flows out from the oxidation furnace 3.
Since O ₂ is completely separated from CO ₂ and H ₂ O by the presence of the second column or cooling trap 4, O ₂
There is also no risk of damaging the function of the reduction furnace 5. Note that the second column or cooling trap 4 after O ₂ separation may be backflushed or flushed in order to send CO ₂ to the reduction reactor 5.
Carrier gas B is useful for this purpose.

Furthermore, in the example shown in the drawings, CO, CO ₂ and CH ₄ are sent to the flame ionization detector 6 through the flow path 7.
The design is such that CO and CO 2 pass through the reduction furnace 5, and the reduction furnace 5 converts these CO and CO ₂ into CH ₄ and it is also possible to measure all three components as CH ₄ , so CH ₄ can be measured in advance and then This device can be effectively used not only to measure the concentration of non-methane organic compounds, but also to measure the concentrations of CO and CO ₂ in samples, such as measuring three components.

[Brief explanation of the drawing]

The drawings are explanatory diagrams showing the configuration of the present invention. 1... Sample valve, 2... First column or cooling trap, 3... Oxidation furnace, 4... Second column or cooling trap, 5... Reduction furnace, 6... Hydrogen flame ionization detector, A, B ...carrier gas, a
...Oxygen, b...Hydrogen, c...Air.

Claims (1)

[Claims] 1. A first column or cooling trap that separates CO, CO ₂ and CH ₄ in a sample from non-methane organic compounds; An oxidation furnace for oxidizing, a second column or cooling trap for separating H ₂ O and CO ₂ generated from the oxidation furnace from O ₂ , and directing the CO ₂ retained in the second column or cooling trap to the reduction furnace. a flow path switching device for outflow transfer;
said reduction furnace for reducing CO ₂ discharged from said second column or cooling trap to CH ₄ , and CO, CO ₂ and CH ₄ in the sample exiting said first column or cooling trap and said reduction; A device for measuring the concentration of non-methane organic compounds, characterized in that it is equipped with a detector such as a hydrogen flame ionization detector arranged so that CH ₄ flowing out from the furnace passes through. 2. The non-methane organic compound concentration measuring device according to claim 1, wherein CO, CO ₂ and CH ₄ in the sample reach the detector through the reduction furnace.