Device for measuring the flow of carrier gas in capillary gas chromatography

 

(57) Abstract:

The device includes a flow sensor auxiliary gas is mixed with the carrier gas, turbolister flow of the gas mixture, coupled with thermal flow meter associated with measuring and sampling devices. The socket for the supply of the carrier gas through the alternating laminar throttle is connected to the line supplying the carrier gas into the inlet node of the sample, is connected to a capillary chromatographic column. The laminar resistance of the inductor is equal to the resistance of the chromatographic column or differs from it in a known number of times. The invention provides the possibility of measuring very low flow of carrier gas during the chromatographic analysis without disconnecting the capillary column from the detector. 1 Il.

The invention relates to the field of analytical techniques, namely, devices for measuring gas flow in capillary gas chromatography.

Known and often used in capillary gas chromatography soap film flowmeters (Kremlin PP Flow meters and counters. - Leningrad: Mashinostroenie, 1989, S. 619), the flow of carrier gas which is determined by the speed of the motion automate the process of measuring the flow of carrier gas.

The closest in technical essence is a flow meter for gas chromatography, contains a chamber with inlet and outlet fittings that hosts thermistors connected to the follower connected to the measuring and sampling devices, and the input valve through turbolister and the line connected to the flow sensor extra gas, and the line is equipped with a fitting to connect the chromatographic column (Copyright certificate of the Russian Federation N 3161, G 01 F 1/68. "Utility models, industrial designs", N 11, 1996).

The disadvantage of partial thermal flow meter is for measuring the flow of carrier gas must be disabled capillary chromatographic column from the detector, which makes it impossible for operational (process analysis) control of this important parameter chromatographic analysis and eliminates automation stabilization mode chromatograph with a capillary chromatographic column.

The technical result is to enhance the functionality of thermal flowmeter for measuring the flow of carrier gas capillary chromatography.

The technical result is achieved that the device is I, flow sensor auxiliary gas is mixed with the carrier gas, turbolister flow of the gas mixture, coupled with thermal flow meter associated with measuring and sampling devices, the socket for the supply of the carrier gas is connected through a variable laminar flow reactor with a line for supplying a carrier gas into the inlet node of the sample, is connected to a capillary chromatographic column. Moreover, the resistance of the variable laminar throttle is equal to the resistance of the chromatographic column or differs from it in a known number of times. Compared with the prototype of the proposed design has a distinctive feature in the set of elements and their mutual arrangement.

The drawing shows a diagram of the device for measuring the flow of carrier gas in capillary gas chromatography.

Device for measuring the flow of carrier gas in capillary gas chromatography contains a heat flow meter 1 flow sensor auxiliary gas 2, turbulizing stream 3, measuring 4 and reference 5 devices, the nozzle 6 for supplying a carrier gas. The nozzle 6 through the alternating laminar orifice 7 is connected to a line 8 for supplying a carrier gas into the inlet node samples 9 to kotary flow divider 12.

The resistance of the inductor 7 in a known number of times differs from the resistance of the capillary column 10 or equal.

The operation of the device is as follows.

The flow of carrier gas (usually helium or hydrogen, is passed through line 8 to the input node of the sample 9 and AC laminar orifice 7. From the input device samples the main part of the flow of carrier gas through the orifice 12 of the flow divider is discharged into the atmosphere, and the remaining (1/50 - 1/100 of the total flow) portion is in the chromatographic capillary column 10 and then to the detector 11, as these items are used for chromatographic analysis.

Through a variable orifice 7, the carrier gas is supplied to the nozzle 6. This stream is mixed with a constant flow rate and composition of the stream of auxiliary gas (air, nitrogen, carbon dioxide), coming from the flow sensor 2. After homogenization of the gas mixture in turbolister 3 the gas stream enters the heat flow meter 1, the signal of which is defined in this case as heat capacity, and mainly by thermal conductivity of the gas mixture, and the latter varies depending on the concentration of the carrier gas flow auxiliary gas, i.e. sdes device according to the signal of thermal flowmeter is determined by the value of this consumption. If you know the ratio of the resistance of the chromatographic capillary column 10 and AC laminar throttle 7, the measurement of the flow rate of the carrier gas coming from the reactor 7, allows you to define the flow of carrier gas through the capillary column 10 and the detector 11. The most convenient option is the implementation of the device in the case where the resistance of the capillary column and a variable inductor are the same. Then the flow of carrier gas through the capillary column will be equal to its consumption, as measured by partial thermal flow meter. Equality resistance chromatographic column and laminar throttle is achieved when the initial adjustment of chromatographic setup by changing the value of resistance of the variable inductor 7. As capillary chromatographic column is liminary resistance and the inductor 7 is laminar, while further work chromatographic setup by different supply pressure) the flow of carrier gas through the orifice 7 will change as well as through the chromatographic column.

This device allows the measurement results of the flow of carrier gas at the outlet orifice 7 to judge the flow of gas to the CSO solutions are

- the ability to measure small (0.2 to 2.0 cm3/min) cost carrier gas in capillary gas chromatography without disconnecting the capillary column from the detector during the chromatographic analysis;

- ability to automate the measurement of the flow of carrier gas and, as a consequence, the possibility of automatic stabilization of the flow of carrier gas through the respective controllers that is connected to the device.

Device for measuring the flow of carrier gas in capillary gas chromatography of the proposed design can be implemented on the basis of the serial thermal flow meter used to measure flow in a Packed gas chromatography.

Trim the last serial flow sensor, turbulization and variable laminar orifice provides the ability to automatically measure and stabilize mirrorshades in capillary gas chromatography.

Device for measuring the flow of carrier gas in capillary gas chromatography, contains the socket for the supply of the carrier gas, the flow sensor auxiliary gas is mixed with the carrier gas, turbolister the flow of gases is to be so, the socket for the supply of the carrier gas is connected through a variable laminar flow reactor with a line for supplying a carrier gas into the inlet node of the sample, is connected to a capillary chromatographic column, and the resistance of the variable laminar throttle is equal to the resistance of the chromatographic column or differs from it in a known number of times.

 

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