Gas analysis method

FIELD: test equipment.

SUBSTANCE: invention refers to analysis of the quantity of impurities in carbon dioxide during manufacturing and/or cleaning process. Measurement method of concentration of impurities during gas cleaning consists in the fact that, first, gas flow containing impurities passes through gas absorbing device during the time period at ambient temperature or higher so that impurities can be absorbed. Than gas flow movement is stopped. Then, desorption and analysis of impurities in stopped gas flow movement is performed by means of detector. At that, impurities have been chosen from the group consisting of H2S, COS, dimethyl sulphide, benzene, aldehydes, spirits with low length of carbon chain and hydrocarbons. Also, in the proposed method, gas absorbing device includes column with absorbent layer in gas chromatograph, and gas is desorbed from column with absorbent layer through gas-distributing column.

EFFECT: improving accuracy and reducing costs for measurement of concentration of impurities during gas cleaning.

9 cl, 1 dwg


The technical field to which the invention relates.

The present invention provides a method of analyzing gases. More specifically, this invention provides a method of analyzing impurities in carbon dioxide in the production process and/or cleaning.

The level of technology

Carbon dioxide has a number of industrial and domestic applications, and many of them require that carbon dioxide was clean various impurities. Unfortunately, carbon dioxide, obtained from natural sources, such as gas wells, chemical processes, fermentation processes, or produced industrially, especially carbon dioxide, produced by burning hydrocarbons, often contains impurities of sulfur compounds, such as carbondisulfide (COS) and hydrogen sulfide (H2S), oxygen-containing compounds, such as acetaldehyde and alcohols, and aromatic compounds such as benzene. When carbon dioxide is suitable for this application, which requires carbon dioxide of high purity, such as the production and purification of food products, including aeration beverages, pharmaceuticals and electronic devices, the number of sulphur compounds and other hydrocarbon impurities contained in the gas stream must be reduced before use. The level of necessary purification of the impurities varies depending on the use of carbon dioxide. For example, for use in beverages total sulfur content in carbon dioxide (CO2) should ideally be less than 0.1 parts per million (ppm), and the content of aromatic hydrocarbons should be less than 0.02 h/million To apply for the electronic clearing is necessary that the content of heavy hydrocarbons was less than 0.1 h/million

In order to ensure that cleaning methods reduce the impurity content to the desired level, the necessary methods of analysis that reliably and cost-effectively measure the content of impurities such as sulfur compounds, aldehydes, alcohols and aromatic compounds in very low concentrations (ppm and ppb - h/bn). Available a variety of ways to identify these impurities, including gas chromatographs with various detectors, analyzers, total hydrocarbons and total sulfur, GC-MS and some infrared detectors. Most of the available methods of analysis are tens of thousands of dollars and too expensive for many companies for the production and purification of carbon dioxide.

The present invention provides a simple, effective and inexpensive method for analysis of various impurities in gases, such as carbon dioxide, during production, purification and use.

The invention

The present invention offers the pic is b measuring the concentration of impurities during the purification of gas, includes: a) pass the gas stream containing impurities through the adsorbing gas unit for a period of time at ambient temperature or higher, so that impurities were adsorbed; b) stopping the flow of gas; and C) deformirovanie and analysis of the resulting gas stream using a detector.

The present invention also provides an analytical method for measuring the concentration of impurities during the production and purification of carbon dioxide comprising: a) pass the gas stream containing impurities through the adsorbing gas unit for a period of time at ambient temperature or higher, so that impurities were adsorbed; b) stopping the flow of gas; and C) deformirovanie and analysis of the resulting gas stream using a detector.

In the embodiment, the gas stream is a stream of carbon dioxide. Adsorbing gas is a column with a layer of adsorbent in the chromatograph. The chromatograph is a gas chromatograph. The detector may be a flame ionization detector (FID) and photometric ionization detector (PID) for the detection of hydrocarbon impurities and a detector such as a flame photometric detector (FPD), sirkenrobinson detector (SCD) and pulsed flame photometric detector (PFPD), for detection of sulfur compounds.

Brief description of drawing

Despite the fact that the description concludes with claims which clearly defines the object that applicants regard as their invention, the present invention can be better understood when considered together with the sole accompanying drawing, which is a detailed description of the analytical setup.

Detailed description of the invention

Carbon dioxide is usually manufactured for industrial processes, contains a number of impurities. These impurities usually present a problem for many uses of carbon dioxide, but in the production of products intended for human consumption, such as carbonated beverages, and electronics industries purity carbon dioxide is the most important, and can affect the taste, quality in accordance with the legislation of the final product.

The crude carbon dioxide gas, which can be obtained from any available source of carbon dioxide, usually contains impurities of sulfur compounds, such as carbondisulfide, hydrogen sulfide, dimethyl sulfide, sulfur dioxide, and mercaptans and hydrocarbon impurities such as aldehydes, alcohols, aromatic compounds, propane, ethylene and other impurities, such as water and carbon monoxide. The present invention describes a novel with the persons identify some impurities. The idea of the present invention is not limited to carbon dioxide and applicable for detection of impurities in other gases.

In the context of the present invention various admixtures of carbon dioxide analyzed by analyzer amounts of sulfur and analyzer number of hydrocarbons. Can be used with other detectors for the analysis of other impurities, such as galoidovodorodami, in other gases. For carbon dioxide, two of the analyzer can be a single node, such as a gas chromatograph, or they may represent a separate nodes. Before analysis of the various impurities of sulfur and hydrocarbons concentrate in order to increase their number in the sample. This stage increases the detection limits of the different analyzers. This is particularly useful for such impurities as benzene, which must be reduced to values below 20 h/bn for use in beverages. This method involves the adsorption is carried impurities within a few minutes on the adsorbent, selective with respect to the analyzed mixture. For concentration of benzene can be used such as an adsorbent, as a Poropak q After the adsorption is carried impurity adsorption column quickly heat up and send impurities in the separation column and then to the detector to determine the number. If for analysis using gas HRO shall atograph, the adsorption column can be located inside the chamber thermostat gas chromatograph or outside it. To reduce cost, it is preferable to arrange the separation column and the adsorption column inside the chamber thermostat GC.

The concentration of impurities before analysis allows to use low-cost detectors for analysis of various impurities. For example, for measuring the content of 20 hours per billion of benzene in carbon dioxide required expensive photoionization detector (PID), whereas after concentration of the sample can be used much more cheap a flame ionization detector (FID). Also for the detection of sulfur in the range from 20 to 50 h/bn required expensive gray-chemiluminescence detector (SCD), whereas after concentration of the sample can be used more cheap flame photometric detector (FPD).

Sulfur analyzer analyzes how the total sulfur content, sulfur compounds at different stages of the process. For pure for use in beverages carbon dioxide total sulfur content in the product, except for sulfur dioxide, should be below 0.1 ppm, and the content of sulfur dioxide should be less than 1 h/million For measuring total sulfur sulfur impurities are oxidized to sulfur dioxide in a catalytic reaction using resistant ser the catalyst or the ozone generator, usually based on corona discharge. Sulfur dioxide after oxidation analyzed using sensitive to sulfur detector, such as gray-chemiluminescence detector (SCD), flame photometric detector (FPD) or a pulsed flame photometric detector (PFPD). When authentication is required sulfur compounds, sulfur impurities can be further concentrated and sent directly to the separation column and the detector, bypassing oxidative node.

The content analyzer hydrocarbon analyses as total hydrocarbons (such as methane), and separate the hydrocarbons at different stages of the process. For pure for use in beverages carbon dioxide total hydrocarbons in the product should be below 50 ppm with different limits for individual compounds, such as benzene (<20 billions of shares), acetaldehyde (<0,1 ppm) and methanol (<10 ppm). For demanding high purity applications in the electronics content of heavy hydrocarbons (>C3should be below 0.1 h/million For measuring the total content of hydrocarbons, as the hub of the sample and the separation column is passed, and the sample is exposed directly to the FID to measure. For the measurement of the individual hydrocarbon components of the sample sent to the hub and in the separation to which the PMC and is directed to the FID detector for analysis.

Details of the analytical system shown in the drawing. In the drawing, the pipe 14 is a line feed sample analytical units. Pipe 16 directs a portion of the sample gas through the valve 18 and pipe 26 to a multi-way valve 28A. A carrier gas, such as nitrogen, is directed through the pipe 20 and valve 22, connecting with the pipe 26 and mixing with the gas sample.

Pipe 30 directs the gas sample in the hub 42A, the separation column 43A and then to the detector 44. Analysis data collected at the detector, proceed along the line 48 in the form of a signal on the integrator/computer, which is not shown. For analysis of hydrocarbon components can be used FID (flame ionization detector).

Another part of the sample gas is directed through the pipe 14 to the pipe 32, where it is mixed with air which enters through the pipe 34. This gas sample is directed to the optional oxidation catalyst sulfur or ozone generator 36 and through a pipe 38 to a multi-way valve 28B. Pipe 39 directs the sample 42B, the separation column 43B and the other detector 46. For detection of sulfur detector 46 may be a FPD (flame photometric detector). Line 52 extends from the detector 46 and delivers the data analysis in the form of a signal on the integrator/computer, which is not shown.

thermostat chamber gas chromatograph 65 accommodates both the detector is such as nodes detection of sulfur and hydrocarbons, but it can also include a column that hub and gas chromatographic column in one integrated node. It is preferable to reduce the total cost of the analytical system.

The valves 28A and 28B on the drawing receive samples with various attached parts of the cleaning process, and the site from which the specimen is obtained, can be tracked by computer. This allows you to monitor impurities at different stages of the process.

The signals from the detectors is converted into the concentration of various impurities using an integrator and/or computer and information can be displayed for use by the operator or transferred to the Central point. In the case of a sharp increase in the level of impurities or other data indicating that the required level of purity is not achieved, the operator can pause or stop the process of cleaning up until the deviation will not be investigated.

Setting and methods of the present invention is designed to solve problems with impurities in carbon dioxide, especially in carbon dioxide supplied in place of its use in industrial processes. By simultaneously carrying out the purification and analysis of the operator of the production equipment can be sure of a stable providing carbon dioxide guaranteed quality.

is the industry production or consumers, for which the present invention is of interest, include, but are not limited to, the production and processing of food products; manufacture of electronics, electronic components and parts; clearance of drugs; aeration soft drinks, beer and water; capping of containers and storage tanks containing flammable liquids and powders; covering substances, decaying in the air, such as vegetable oil, spices and incense.

Example 1

The sample containing 1 ppm of benzene in carbon dioxide, is passed at a flow rate of 50 cm3/min through a variety of 2.0"1/8" (5 cm 0.3 cm) columns filled with activated alumina, silica gel, zeolite DAY and Poropak Q, respectively. The column is placed in a chamber thermostat gas chromatograph at 50C and added to the FID detector. The traffic flow pattern continues for about 10 minutes, and for none of the columns do not see the breakthrough of benzene.

The movement of the sample flow is stopped and passed through the column with nitrogen as the carrier gas. The temperature in thermostat was raised to 150C in less than one minute and observing the output column using the FID detector. Very little desorption of benzene observed for activated alumina, silica gel and DAY due to their high affinity for benzene is. However, with Poropak Q benzene fully desorbed less than 1 minute.

For Poropak Q concentration ratio is equal to 500 compared to 1 cm3sample. Provided that the limit of detection of benzene equal to 0.5 ppm for FID detector, the method of concentration of the sample makes it possible to measure the concentration of benzene up to 1 billion shares with the same detector. This method is suitable for other impurities, such as aldehydes and alcohols. This method is also suitable for other gases and other impurities.

The present invention is particularly suitable for detecting impurities in a partially purified product, or final product, because the lower levels of impurities in the gas stream does not require a large adsorption capacity in the hub 42A and 42B, which operate at ambient temperature or higher. In addition, the adsorbents in these hubs must be a weak adsorbents (such as Poropak Q for benzene), so that impurities are easily deformirovanii when heating thermostat GC. Strong adsorbents, such as zeolites and activated alumina, fit poorly, because they're harder to decarbonate impurities.

Although the present invention is described with reference to some embodiments of the example, numerous changes, is dopolneniya and omissions deems necessary specialist in the art, can be made without going beyond the nature and scope of the present invention.

1. The method of measuring the concentration of impurities during the purification of gas, which includes
a) pass the gas stream containing impurities through the adsorbing gas unit for a period of time at ambient temperature or higher, so that impurities were adsorbed;
b) stopping the flow of gas; and
C) deformirovanie and analysis of impurities in the stopped flow of gas through the detector.

2. The method according to claim 1, wherein the gas is carbon dioxide.

3. The method according to claim 1, wherein the impurity is selected from the group consisting of H2S, COS, dimethyl sulfide, benzene, aldehydes, alcohols of low carbon chain length and hydrocarbons.

4. The method according to claim 1, in which the adsorbing gas device includes a column with a layer of sorbent in the gas chromatograph.

5. The method according to claim 4, in which the gas is desorbed from the column with a layer of sorbent through the gas separation column.

6. The method according to claim 4, in which the gas chromatograph includes an analytical device for measuring the content of impurities of organic compounds selected from the group consisting of benzene, aldehydes, alcohols of low carbon chain length and is of glendorado.

7. The method according to claim 4, in which gas chromatograph connected to an analytical device for measuring the content of sulfur compounds.

8. The method according to claim 1, wherein the detector is selected from a flame ionization detector (FID) and photometric ionization detector (PID) for the detection of hydrocarbon impurities and flame photometric detector (FPD), gray-chemiluminescence detector (SCD) and pulsed flame photometric detector (PFPD) for the detection of sulfur compounds.

9. The method according to claim 5, further comprising increasing the temperature of the gas separation column.


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