Monitoring gas impurities with total sulfur detection
A system and method for determining impurities in a beverage grade gas such as CO 2 or N 2 relies on FTIR gas analysis for measuring non-sulfur impurities as well as SO 2 . CO 2 % also can be determined. A multiplexer selects a sample gas from multiple gas samples. Conversion of reduced sulphur present in some impurities to SO 2 is conducted in an oxidizing furnace. Climate control and measurements of oxygen gas impurities also can be provided.
1. A system for analyzing a beverage grade gas, the system comprising:
a multiplexer for selecting a gas sample from multiple gas samples;
a spectrometer including a gas cell for detecting an absorbance spectrum of gas in the gas cell;
an oxidizing furnace for converting reduced sulfur present in the gas sample to SO 2 ;
an arrangement including a device for directing the gas sample to the spectrometer or to the oxidizing furnace; and
a computer module for operating the multiplexer, the oxidizing furnace and/or the device for directing the gas to the spectrometer or to the oxidizing furnace;
wherein the computer module is configured to operate the device for directing the gas to the spectrometer to switch conditions in the gas cell between an atmospheric pressure and a pressure above atmospheric.
2. The system of claim 1 , wherein the gas cell is a multiple path type cell and/or wherein the gas cell is configured for pressures higher than atmospheric.
3. The system of claim 1 , wherein the spectrometer is provided with a FTIR detector for measuring SO 2 and non-sulfur impurities in the sample gas.
4. The system of claim 1 , further comprising conduits, valves, an oxygen analyzer, and/or controls for pressure, temperature and/or flow rates.
5. The system of claim 1 , wherein the system does not include a UV fluorescence apparatus.
6. The system of claim 1 , wherein the multiplexer is configured to receive gas feeds from multiple plant locations.
7. The system of claim 1 , wherein the computer module further comprises one or more functions for collecting, analyzing and/or reporting data from the spectrometer.
8. The system of claim 1 , wherein the computer module comprises connections to one or more of the multiplexer, the spectrometer and the oxidizing furnace and/or is configured for local area network communications.
9. The system of claim 1 , further comprising software for collecting, analyzing and/or reporting data.
10. The system of claim 1 , further comprising calibration information for pure CO 2 and/or one or more impurity for the spectrometer.
11. A method for analyzing a beverage grade gas, the method comprising:
(a) selecting a gas sample from multiple gas samples;
(b) directing a first portion of the gas sample to a gas cell;
(c) measuring impurities present in the gas cell with a spectrometer, wherein the impurities include SO 2 ;
(d) directing a second portion of the gas sample to an oxidizing furnace;
(e) converting reduced sulfur present in the second portion to SO2;
(f) directing gas exiting the oxidizing furnace to the gas cell;
(g) measuring a total SO2 in the gas cell;
(h) repeating steps (a) through (g); and
(i) switching conditions in the gas cell between an atmospheric pressure and a pressure above atmospheric.
12. The method of claim 11 , wherein step (c) is conducted at a pressure higher than atmospheric and/or wherein step (g) is conducted at atmospheric pressure.
13. The method of claim 11 , wherein total SO 2 measured in the second portion of the gas sample is compared with SO 2 measured by the spectrometer in the first portion of the gas sample to determine a TRS amount.
14. The method of claim 13 , further comprising controlling gas pressure and/or gas temperature in the gas sample cell and/or purging the sample gas cell after step (c).
15. The method of claim 11 , wherein data obtained for impurities in the first portion of the gas sample are compared with calibration data.
16. The method of claim 11 , wherein the impurities are selected from the group consisting of SO 2 , total sulfur, NH 3 , CO, NO, NO 2 , H 2 O, hydrogen cyanide (HCN), CS 2 , methanol, acetaldehyde, methane, total hydrocarbons, benzene and total aromatic hydrocarbons and the beverage grade gas is CO 2 or N 2 .
17. The method of claim 11 , wherein the gas sample is selected from multiple gas samples, obtained from different locations in a plant, by a multiplexer.
18. The method of claim 11 , further comprising measuring oxygen gas present in the sample gas.
19. The method of claim 11 , wherein a CO 2 % in the first portion of the gas sample is determined by the spectrometer and compared to calibration information.
20. The method of claim 11 , further comprising controlling at least one of steps (a) through (h) automatically.
21. The method of claim 11 , wherein the method does not include detecting SO 2 by UV fluorescence.
22. A system, comprising:
a spectrometer including a gas cell for detecting an absorbance spectrum of gas in the gas cell;
an oxidizing furnace for converting reduced sulfur present in the gas to SO 2 ;
an arrangement including a device for directing the gas to the gas spectrometer; and
a computer module configured to operate the device for directing the gas to the spectrometer to switch conditions in the gas cell between an atmospheric pressure and a pressure above atmospheric.