SU641284A1 - Method of spectrochromatographic analysis of multicomponent gas mixtures - Google Patents

Description

The invention relates to the field of spectral analysis, in particular spectrochromatography analysis of multicomponent gas mixtures, including oxygen, hydrogen, nitrogen, as well as oxygen- and nitrogen-containing compounds. The method can be used in chemical, petrochemical and other industrial areas to determine the composition of multicomponent gas mixtures containing various elements.

Methods are known for the spectral analysis of myocomposite gas mixtures by sequentially measuring the intensity of the spectral lines of the elements of a compound in the gas discharge sector.

The closest technical solution is a method for the chromatographic analysis of mycomponent gas mixtures, including pulsed injection of a sample into a carrier gas stream, chromatographic separation of substances, and registration of the integer emission lines of elements in the spectrum above the high-frequency discharge.

However, the known methods do not allow analyzing the compositions of fast-changing multicomponent single mixtures with high accuracy if the time for changing the composition of the mixture is shorter than the total time for determining the concentrations of all components. This is due to the fact that all components, when different mixtures are present in their mixtures, are determined from different samples. Orienting this, before introducing each subsequent sample, the spectrometer must be rearranged to the emission line of the element being determined. These additional actions complicate and prolong the analysis.

The purpose of the present invention is to accelerate and simplify the analysis process.

It is achieved by the fact that the components have a definite change in the intensity of the emission line of one of any elements under conditions of a FULL and constant saturation of the tube walls with this element.

The components, for example, oxygen, nitrogen, and hydrogen, are determined by the change in intensity, the oxygen emission line O 7771.9A, metered into the discharge tube in an amount of about 10% volume fraction.

Claims (2)

FIG. I shows a diagram of a device implementing the proposed method; in fig. Figure 2 shows a graph of the dependence of the intensity of the emission oxygen emission line on the number of oxygen and nitrogen introduced into the discharge tube; in fig. 3 is a spectrochromatogram of the determination of oxygen, nitrogen and hydrogen with their joint presence of 8 helium. A dynamic equilibrium between the amount of this element on the tube wall and in the discharge plasma is established in the discharge tube of a multicomponent gas mixture containing element I, which is sorbed by its walls. This state of the discharge tube is characterized by the constant brightness of the spectral emission lines of element 1. When another kind of element 2, which also absorbs its walls and interacts with element 1, is in equilibrium, the equilibrium state is disturbed. Part of the previously sorbed element is desorbed from the walls of the discharge tube, the concentration of its atoms in the discharge increases, which leads to an increase in the intensity of the emission spectral lines of element 1, to one of which the spectrometer is tuned. Under conditions of constant full saturation of walls with element I, the ratio between the number of element 2 supplied to the discharge tube and the change in the intensity of the emission line of element I is proportional to the number of element 2. The fundamental difference between the proposed method for analyzing multicomponent gas mixtures is that Componeites are determined from a single sample containing different elements, by changing the intensity of the emission line of one element, injected into the discharge tube in an amount of about ensuring saturation of the tube walls with this element, at least, close to complete. Example. Micro-impurities of oxygen and nitrogen were analyzed with their joint presence in helium. From the flow, the impurity gels were sorbed by the sorbent in a cooled trap (Fig. 1) at the boiling point of nitrogen. By heating the trap to room temperature, impurities were injected with a pulse into the flow of gels and transferred to a separating column 2 and from there into a flow-through quartz-type discharge tube 3, into which oxygen and nitrogen arrived at a time interval of 40 s. The amount of oxygen required to constantly maintain the saturation of tube 3, which is close to complete, was provided with a capillary strain gauge 4 installed before cutting 1. At the same time, oxygen was metered into the discharge tube in the amount of about 10 parts by volume. The same leak 4 into the discharge tube 3 was metered continuously and nitrogen in an unsatisfactory amount, for example, about 10 by volume. The discharge in tube 3 was excited by a generator (“Luch-58) on. the frequency of 2375 MHz. The diameter of the tube in the zone of discharge 4 mm. This zone is air cooled. The gels were maintained through the tube at 0.4 nem / sec. The dilution degree was 20 mm Hg. Art. The line intensities were recorded with a spectrometer. DFS-12 tuned to the oxygen line 01 7771.9 A. In FIG. Figure 2 shows the dependence of the change in the intensity of the emission line of oxygen on the amount of oxygen (straight line I) and nitrogen (straight line 2) introduced into the discharge tube. The change in intensity is expressed in square millimeters of the area of the spectrochromatographic peaks in the chart of the recorder, and the amount of oxygen and nitrogen in microliters. As can be seen from the above dependencies, the sensitivity in the determination of nitrogen is close to that in the determination of oxygen, while in the known method the sensitivity in nitrogen is 3 times lower than in oxygen. Similarly, trace impurities of oxygen, nitrogen and hydrogen were analyzed with their joint presence in helium. FIG. Figure 3 shows the spectrogram of the determination of these impurities, where I is the peak of hydrogen, 2 is oxygen, and 3 is nitrogen. In order to obtain comparative data, the said gas multicomponent mixtures were analyzed in parallel in a known manner. In both cases, the time of complete analysis was monitored. At concentrations of oxygen and nitrogen in helium of the order of the volume fraction by a known method, the time of complete analysis was not less than 30 minutes, and according to the proposed procedure - not more than 10 minutes. In the determination of oxygen, nitrogen, and hydrogen in helium, the time for complete analysis was 45 and 15 min, respectively. The ability to analyze all the components of the analyzed gas mixture from one sample by changing the intensity of the emission line of one of the elements favorably distinguishes the proposed method from the known one, since it greatly simplifies the analysis, excluding the operations associated with the spectrometer restructuring, at least 3 times analysis time, thereby increasing the accuracy of the method in the analysis of rapidly changing gas mixtures over time. Claim 1. Method for spectrochromatographic analysis of multicomponent gas mixtures, including pulsed sample injection into a carrier gas stream, chromatographic separation of substances and recording the intensity of the emission lines of elements in the microwave spectrum, characterized in are on a change in the intensity of the emission line of any one element under conditions of complete and constant saturation of the walls of the discharge tube with this element. 2. The method according to claim 1, wherein that the components, for example, oxygen, a.ior, and hydrogen, are determined by the change in the intensity of the oxygen line of the oxygen line 01 7771.9A, which is metered into the discharge tube in the amount of about 10 vol. Not VVVA samples : if i 1 Have JO f.t tS