APPARATUS AND METHOD FOR GENERATING NITROGEN OXIDES

• US 20080176335A1
• Filed: 12/31/2007
• Published: 07/24/2008
• Est. Priority Date: 12/29/2006
• Status: Abandoned Application

• Current Assignee: Thermo Electron Manufacturing Limited (Thermo Fisher Scientific Incorporated)
• Original Assignee: Thermo Fisher Scientific Incorporated
• Inventors: SMEETS, Louis Marie, ALBERTI, David Marco Gertruda
• Application Number:
  US11/967,625
• Publication Number:
  US 20080176335A1
• Time in Patent Office: Days
• US Class Current: 436/114
• CPC Class Codes: C01B 21/203 Preparation of nitrogen oxides using a plasma or an electric discharge
• CPC Class Codes: G01N 31/12 using combustion G01N25/20 takes precedence
• CPC Class Codes: Y10T 436/176152 Total nitrogen determined

Abstract

A combustion analyzer apparatus and method for combustion analysing a sample, the analyzer comprising a combustion chamber (82) for receiving a sample for combustion therein to form combustion products, and a fluid supply apparatus for supplying fluid(s) into the chamber. The fluid supply apparatus (130-140) comprises a nitrogen oxides (NO_x) generating apparatus (140,190,210,240) and is arranged to supply NO_x into the combustion chamber. A yield of sulphur dioxide in the combustion products may thereby be improved. The NO_x generating apparatus may be operated at a raised working temperature. The NO_x generating apparatus may be provided by an ozonator with a supply of nitrogen and oxygen. A Venturi tube arrangement (246) may draw the generated NO_x into a (carrier or oxygen) gas line to the combustion chamber. Ozone may be supplied to the combustion products to convert nitrogen monoxide therein to nitrogen dioxide. The NO_x and ozone may be supplied by a single device (210,240).

Claims

1. A combustion analyzer for combustion analysing a sample, the analyzer comprising:

a combustion chamber for receiving a sample for combustion therein to form combustion products; and

a fluid supply apparatus for supplying one or more fluids into the combustion chamber,

wherein the fluid supply apparatus comprises a nitrogen oxides (NO_x) generating apparatus and the fluid supply apparatus is arranged to supply NO_x into the combustion chamber.

2. The analyzer of claim 1, wherein the NO_x generating apparatus comprises an electric discharge generator having a discharge region, the electric discharge generator being arranged to receive a supply of nitrogen and a supply of oxygen in the discharge region and to provide an electric discharge through the discharge region such that NO_x is generated.

3. The analyzer of claim 2, wherein the supply of nitrogen and the supply of oxygen are provided by air.

4. The analyzer of claim 1, wherein the NO_x generating apparatus is switchable between a first on state in which NO_x may be generated and supplied to the combustion chamber and a first off state in which NO_x may not be generated.

5. The analyzer of claim 1, the fluid supply apparatus further comprising a NO_x supply line for receiving generated NO_x from the NO_x generating apparatus, wherein the NO_x supply line has a connection into the combustion chamber.

6. The analyzer of claim 1, the fluid supply apparatus further comprising a NO_x supply line for receiving generated NO_x from the NO_x generating apparatus and an oxygen supply line and/or a carrier gas supply line which feeds into the combustion chamber, wherein the NO_x supply line has a respective connection into one or both of the oxygen supply line and the carrier gas supply line.

7. The analyzer of claim 1, further comprising:

a combustion products line connected to the combustion chamber for transferring combustion products therefrom to a downstream detector; and

an ozone supply apparatus having a connection into the combustion products line for supplying ozone thereto.

8. The analyzer of claim 1, wherein the NO_x generating apparatus comprises a heating apparatus arranged to raise a working temperature of the NO_x generating apparatus.

9. The analyzer of claim 8, wherein the heating apparatus is arranged, in use, to transfer heat from an ozone killer unit to the NO_x generating apparatus.

10. The analyzer of claim 1, wherein the NO_x generating apparatus is provided by an ozonator arranged to receive a supply of nitrogen and a supply of oxygen to generate NO_x therefrom.

11. The analyzer of claim 7, wherein the NO_x generating apparatus and the ozone supply apparatus are provided together by:

an electric discharge generator having a discharge region and arranged to provide an electric discharge through the discharge region;

a first, NO_x conduit disposed in a first part of the discharge region and comprising a NO_x source gas inlet for receiving a supply of NO_x source gas into the NO_x conduit and a NO_x gas outlet for supplying NO_x gas therefrom;

a second, ozone conduit disposed in a second part of the discharge region and comprising an ozone source gas inlet for receiving a supply of ozone source gas into the ozone conduit and an ozone gas outlet for supplying ozone gas therefrom.

12. The analyzer of claim 11, wherein the first conduit is disposed adjacent to the second conduit and separated therefrom by a partition.

13. The analyzer of claim 11, wherein the electric discharge generator comprises a single power and control unit.

14. The analyzer of claim 11, wherein the NO_x gas outlet comprises a Venturi tube having a tube constriction, an intake opening near the tube constriction, and a Venturi tube outlet downstream of the tube constriction, the Venturi tube being arranged to receive a fluid flow through the tube constriction such that NO_x gas is drawn into the intake opening and supplied from the Venturi tube outlet.

15. The analyzer of claim 1, wherein the NO_x generating apparatus comprises:

an electric discharge generator having a discharge region and arranged to provide an electric discharge through the discharge region;

a NO_x conduit disposed in the discharge region and comprising a NO_x source gas inlet for receiving a supply of NO_x source gas into the NO_x conduit and a NO_x gas outlet for supplying NO_x gas therefrom,

wherein the NO_x gas outlet comprises a Venturi tube having a tube constriction, an intake opening near the tube constriction, and a Venturi tube outlet downstream of the tube constriction, the Venturi tube being arranged to receive a fluid flow through the tube constriction such that NO_x gas is drawn into the intake opening and supplied from the Venturi tube outlet.

16. The analyzer of claim 15, wherein the fluid is oxygen and the Venturi tube outlet is configured to supply a mixture of oxygen and NO_x therefrom.

17. A method of combustion analysing a sample in a combustion chamber of a combustion analyzer, the method comprising the steps of:

supplying the sample to the combustion chamber; and

combusting the sample to produce combustion products,

characterised by the step of generating nitrogen oxides (NO_x) and supplying the generated NO_x to the combustion chamber.

18. The method of claim 17, wherein the NO_x is supplied to the combustion chamber before and/or during combustion.

19. The method of claim 17, wherein the NO_x is generated by passing an electric discharge through a mixture of nitrogen and oxygen.

20. The method of claim 19, wherein the mixture is air.

21. The method of claim 17, further comprising the step of supplying ozone to the combustion products to convert at least a proportion of any nitrogen monoxide in the combustion products to nitrogen dioxide.

22. The method of claim 17, wherein the NO_x is generated by an ozonator receiving a supply of nitrogen and a supply of oxygen.

23. The method of claim 17, wherein the NO_x is generated at a temperature of between 30 and 50°

C.

24. The method of claim 21, wherein the NO_x and ozone are generated by:

providing a single electric discharge region;

passing a mixture of nitrogen and oxygen through a first part of the region, to generate NO_x; and

passing oxygen through a second part of the region, to generate ozone.

25. The use of an ozonator with a nitrogen and oxygen supply to generate nitrogen oxides (NO_x) to be supplied to a combustion chamber of a combustion analyzer.