SU496491A1 - Circulating gas chromatograph - Google Patents

Description

(54) CIG CULONION GAS CHROMATOGRAPH

The invention relates to devices for chroma-graphic separation of a mixture of vaaoB and vapors, and can be used in 1Ol, for example, to obtain pure or enriched substances in a semi-industrial scale. Circulated chromatographic schemes are known for the continuous separation of mixtures of gases and vapors in a system of several consecutive columns with moving input and output points of the g-flow and selection of enriched fractions of the mixture from the ends of the chromatographic band in which the selection of the heavy fraction from separate g-azovym flow. Also known are devices for continuous chromatographic separation of mixtures of gases and vapors into two fractions using a moving sorbent layer, but they have a number of design flaws, such as having large rubbing surfaces, which are difficult to repair, and the purpose of the invention is to increase the separation efficiency of the mixtures. This is achieved by linking the columns, divided into three or more groups j, with three groups of switching means, connecting respectively the gas inputs of the device with the inputs of the column groups, the inputs and outputs of the column groups with each other and with the device for entering the separable mixture and the outputs of the groups output channels for collecting separated fractions. FIG. 1 shows a block diagram of the device (one of the embodiments); in fig. 2 - switching circuit elements in three consecutive positions; in fig-. 3 - switching unit (one of the variants). The device contains several, for example, three groups of separation columns 1, 2 and 3, three groups 4, 5, 6 switching means, a device 7 for introducing a separable mixture, two gas inlets 8 and 9 and two channels 1O and 11 for collecting the separated fractions equipped with detecting devices 1 2 and 13 and: Lead “to collectors. The presence of detection devices on both output channels 10 and 11 is not necessary and depends on the specific conditions. Group 4 switching means connects gas inputs 8, 9 to inputs 14, 15, 16 of the respective columns 1, 2, 3, group 5 switching means connects inputs 14, 15, 16 and outputs 17 18, 19 of the columns to me and to the device 7 to inject the separable mixture, and group 6 connects the exits 17, 18, 19 of the columns with channels 10, 11 to collect the separated fractions. I Each of the groups 4-6 switching means is made in the form of a block of pneumatic diaphragm valves 2O (see Fig. 3), the gas channels 21 and 22 of which on one side of the valves are connected in pairs with the common output channel 23 of the corresponding pair. The number of pairs of diaphragm valves is equal to the number of column groups. With three groups of separation columns, the number of membrane valves 20 in each block is six. Each group of 4-6 switching means has three exits on one side and a gap on the opposite side. FIG. 3 for clarity. Two caps of diaphragm valves with diaphragms are conventionally removed and the body is shown in parts but in section. The pressure for closing the valves 20 is fed into the supramembrane cavities through channels 24 connected to the command device (not shown). The valves open when the pressure above the membrane is released under pressure in controlled gas paths. The type and connection scheme of the detecting devices 12, 13 depend on the specific conditions and are not included in the sausage of the present invention. In the general case, a flame ionization detector can be used. As a device for introducing a separable mixture, any known design can be used to supply a separable gas or vapor mixture to the system at a constant rate. The device works as follows. The flow of carrier gas entering through the inlet 9 into the device enters the / p position of the device; shown in FIG. 2 &) through group 4 of switching means to input 14 into separation column 1 and then through output 17- into group 5 of switching means, where a flow of the mixture to be separated from the device 7 for the introduction of the separable mixture is added to the flow of gas carrier. Further, the total flow of carrier gas together with the mixture to be separated passes through the inlet 15 to column 2 and exits from there through outlet 18, group 6 of switching means and canal 11 with a detecting device 13 to the collector for sampling the light fraction (not shown). With the atom, the front of the flow of the mixture being separated, moving along column 2, is enriched by the lighter component of the mixture, which, starting at some point in time when the front of the chromatographic strip reaches the exit of column 2, will flow with the carrier gas to the collector fractions. At the same time, the equilibrium part of the chromatographic band remaining in column 1 after the previous switching is pumped by the carrier gas from column 1 through switching commutator unit 5 to column 2, the tail part of which is enriched by the heavier component. The separation conditions are chosen in such a way that by the time the column 2 of the mixed zone of the chromatographic band is approached, its rear border has already managed to leave column 1, in which only a part of the chromatographic band enriched in the heavier component remains. I The remaining in the column 3 after the previous switching of the circuit, the portion of the chromatographic band enriched in the more sorbing component is removed from the device by a second carrier gas stream, which is fed through inlet 8 and passes through group 4 of switching means, inlet 16, column 3, outlet 19 and a group of 6 switching means to channel 10 with a detecting device 12 and further into the collector for the selection of the heavy fraction. The velocity of the carrier gas flow / is chosen so that by the time of the next switching of the scheme, the sorbent in separation column 3 has time to be fully regenerated. When the front of the offset zone of the chromatographic strip approaches the exit of column 2, the device switches from the position shown in FIG. 2a to the position shown in FIG. 26. The flow of carrier gas fed through inlet 9 now passes through columns 2 and 3, the separable mixture is fed to the inlet of column 3, the light fraction is taken from the outlet of column 3, and the remaining 1 column of chromate band is represented by by itself

a heavy fraction is discharged from the carrier gas flow through the inlet 8. When the mixed zone of the hrymatography strip approaches the outlet of the column 3, the device switches from the position shown in FIG. 26, to the position shown in FIG. 2c, and the process continues in the same sequence. In this case, the separation of the continuously injected mixture and the selection of the light fraction is carried out using a single stream, the carrier gas supplied through inlet 9, and the heavy fraction is removed using another gas flow through the inlet 8, the input and output points of which are moved along in series installed columns in sync with switching the input of the mixture to be divided. The selection of light (1) operation is carried out for a certain period of time immediately preceding the moment of switching the device, and the selection of the heavy fraction takes place during the period immediately following the moment of switching.

Both fractions may be cooTBeTCTBeiffO, the least or most sorbing component of a mixture with a certain degree of enrichment, or a mixture of less than or I

; Brlee sorbing components (with multicomponent mixtures) depending on the conditions and tasks of specific work performed.

Subject invention

A circulating gas chromatograph containing columns included in the circulation circuit, a device for introducing the mixture to be separated, two gas paths and a detector, characterized in that, in order to increase the separation performance of the mixture, the columns are separated

into more groups and are connected with three groups of switching means connecting, respectively, both gas inputs of the chromatograph with the inputs of the column groups, the inputs and outputs of the column groups between GOD and with the device for the input of the separable mixture and the outputs of the column groups with the output channels of the device at any position, two or more column groups are sequentially connected to one gas path, the device for introducing the mixture to be divided is connected to the middle section between these column groups, and the remaining column groups are included in the second g-azov trasG

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