Method and apparatus for reducing gas consumption in continuous flow analytical instruments

Patent metadata

Field	Value
Publication number	US-10338044-B2
Application number	US-201615142909-A
Country	US
Kind code	B2
Filing date	Apr 29, 2016
Priority date	Apr 30, 2015
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

A gas transport system includes at least one chemical reactor having at least one inlet and at least one gas outlet and at least one sample introduction unit for delivering the sample into the chemical reactor. The gas transport system at least one carrier gas line fluidly coupled to the chemical reactor inlet for introducing into the chemical reactor carrier gas from a carrier gas source, at least one gas outlet line from the chemical reactor gas outlet, and at least one gas recycling line connected to the gas outlet and/or the gas outlet line by a first gas line junction that is arranged between the chemical reactor and a downstream detection unit on the gas outlet line. The gas transport system is adapted to allow recycling of at least a portion of gas emerging from the chemical reactor outlet back to the chemical reactor via the gas recycling line.

First claim

The invention claimed is:

1. A gas transport system for continuously flushing
a chemical reactor, comprising:
the chemical reactor, the chemical reactor having an inlet and a gas outlet, the inlet for introducing a sample and a carrier gas into the chemical reactor, and the gas outlet for releasing an analyte gas and the carrier gas from the chemical reactor;
a sample introduction unit for delivering the sample into the chemical reactor;
a carrier gas line fluidly coupled to the inlet, the carrier gas line for introducing the carrier gas from a carrier gas source into the chemical reactor;
a gas outlet line from the gas outlet;
a gas recycling line connected to the gas outlet and/or the gas outlet line by a first gas line junction that is arranged between the chemical reactor and a downstream detection unit coupled to the gas outlet line, and connected to the sample introduction unit and/or the inlet and/or the carrier gas line at a second gas line junction;
the detection unit, wherein the detection unit includes a separation unit and a detector downstream of said separation unit, the separation unit is connected to the gas outlet line downstream of the first gas line junction, and the separation unit includes a chromatographic column; and
a gas flow splitter downstream of the separation unit, the gas flow splitter configured for splitting a gas flow stream exiting the separation unit into a first gas stream entering a bypass gas line and a second gas stream entering the detector, the bypass gas line being fluidly connected to the gas recycling line,

wherein the gas transport system is adapted to allow recycling of at least a portion of gas emerging from the gas outlet back to the chemical reactor via the gas recycling line.

2. The gas transport system of claim 1 , wherein the gas recycling line is connected to the gas outlet line or the gas outlet at the first gas line junction, between the chemical reactor and the detection unit, and to the carrier gas line at a second gas line junction.

3. The gas transport system of claim 1 , wherein the carrier gas line comprises at least one in-line gas reservoir to which the gas recycling line is connected.

4. The gas transport system of claim 1 , wherein the inlet comprises a carrier gas inlet and a sample inlet.

5. The gas transport system of claim 1 , wherein the chemical reactor is selected from a combustion reactor, a reduction reactor and a pyrolysis chamber.

6. The gas transport system of claim 1 , wherein the sample introduction unit comprises a sample introduction device and a gas purge line, the gas purge line adapted to provide a stream of gas into the sample introduction device.

7. The gas transport system of claim 6 , wherein the gas recycling line is connected to the gas purge line, enabling recycling of at least a portion of gas exiting the reactor as purging gas for purging the sample introduction device.

8. The gas transport system of claim 6 , comprising one or more flow control units for controlling flow of gas fed into the gas purge line.

9. The gas transport system of claim 8 wherein said one or more flow control units comprise first mass flow controller for controlling flow of carrier gas in the carrier gas line, and a second mass flow controller for controlling flow in the gas purge line.

10. The gas transport system of claim 1 , comprising a valve arranged on the gas recycling line or at the first gas line junction, for controlling gas flow in the gas recycling line.

11. The gas transport system of claim 1 , further comprising at least one chemical trap arranged on the gas recycling line.

12. The gas transport system according to claim 11 , wherein the gas recycling line comprises a recycling split valve upstream of the chemical trap, the recycling split valve having a first position allowing gas to flow through the gas recycling line, and a second position in which gas is prevented from flowing through the gas recycling line.

13. The gas transport system according to claim 12 , further comprising an open vent that is fluidly connected to the recycling split valve, and wherein the recycling split valve releases gas through the open vent in the second position.

14. The gas transport system of claim 1 , comprising a flow controller arranged on the gas recycling line.

15. The gas transport system of claim 1 , wherein the gas recycling line is configured so that during recycling, in the range of about 1-50 vol % of gas from the gas outlet is directed onwards through the gas outlet line and in the range of 50-99 vol % of gas from the gas outlet is directed to the gas recycling line.

16. The gas transport system of claim 1 , wherein the gas recycling line is configured so that when total gas flow from the gas outlet is in the range of about 80 to about 1000 mL/min, in the range of about 5-35 mL/min of gas passes through said first gas line junction onwards through the gas outlet line during recycling.

17. The gas transport system of claim 1 , comprising a compressor arranged on the gas recycling line, to increase the pressure of gas passed through the gas recycling line to the carrier gas line and/or the sample introduction unit.

18. The gas transport system of claim 1 , wherein the detector is selected from the group consisting of a mass spectrometer, a thermal conductivity detector, and an optical spectrometer.

19. The gas transport system of claim 1 , comprising a valve for controlling gas flow in the bypass gas line, wherein said valve is a switch valve, connecting the bypass gas line to the gas recycling line, the switch valve having at least two positions wherein a first position allows flow from the first gas flow junction through the gas recycling line and prevents flow of gas from the bypass gas line to the gas recycling line, and a second position preventing flow from the first gas line junction to the gas recycling line and allowing flow from the bypass gas line to the gas recycling line.

20. The gas transport system of claim 1 , further comprising a controller for controlling a valve position of at least one valve, wherein the controller is adapted to receive an input of at least one system parameter selected from gas concentration in the detector, presence and/or absence of a gas in the detector, and time, and wherein the controller is able to adjust the valve position of the at least one valve based on the at least one system parameter.

21. The gas transport system of claim 20 , wherein the controller is configured to control the valve position of the at least one valve so that in a first position gas is directed to flow through the gas recycling line towards the carrier gas line and/or the sample introduction unit and so that in a second position gas is prevented from flowing through the gas recycling line.

22. A method for managing gas consumption in a continuously flushed elemental analyzer, the method comprising steps of:
(i) streaming carrier gas through a carrier gas line into a chemical reactor;
(ii) introducing a sample from a sample introduction unit into the chemical reactor;
(iii) directing a gas flow from a gas outlet on the chemical reactor through a gas outlet line;
(iv) splitting the gas flow at a first gas flow junction in the gas outlet or gas outlet line, between the chemical reactor and a downstream detection unit, to direct a portion of the gas flow to a gas recycling line leading to the carrier gas line and/or the sample introduction unit and/or the chemical reactor, and a remaining

Assignees

• Thermo Fisher Scient Bremen Gmbh

Inventors

• Schwieters Johannes
• Krummen Michael
• Schlueter Hans-Juergen
• Kracht Oliver

Classifications

• G01N33/0013 Primary

  by a chemical reaction (a chemical reaction taking place or a gas being eliminated in one or more analysing channels G01N33/0024) · CPC title

• G01N30/06

  Preparation · CPC title

• G01N2030/324

  speed, flow rate · CPC title

• G01N2030/025

  Gas chromatography · CPC title

• G01N2030/067

  by reaction, e.g. derivatising the sample · CPC title