Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1993-04-19
2001-07-03
Soderquist, Arlen (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C250S343000, C250S373000, C256S013000, C422S080000, C422S082050, C422S091000, C436S157000, C436S181000
Reexamination Certificate
active
06254828
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns gas analysis apparatus and methods.
A need continues to exist for apparatus for a systematic analysis of gases.
Existing gas analysis cells have large volumes. Consequently a large volume of gas must be flowed into and out of a cell before a new significant reading may be taken. Quantities of available gases make purging inconvenient, wasteful and time consuming.
A need exists for analysis cells which may be readily filled, read and purged.
Instrument calibration requires several steps. A need exists for rapid, accurate calibration.
Gas analysis cells may be large and heavy and many cells may be required. A need exists for a system that is capable of performing such analysis.
SUMMARY OF THE INVENTION
The present invention provides solutions to the long standing needs.
In the present invention, a furnace with two hot zones holds multiple analysis tubes. Each tube has a separable sample-packing section positioned in the first hot zone and a catalyst-packing section positioned in the second hot zone. A mass flow controller is connected to an inlet of each sample packing tube, and gas is supplied to the mass flow controller. Oxygen is supplied through a mass flow controller to each tube to either or both of an inlet of the first tube and an intermediate portion between the tube sections to intermingle with and oxidize the entrained gases evolved from the sample. Oxidation of those gases is completed in the catalyst in each second tube section. A thermocouple within the catalyst pack controls the temperature of the second hot zone, which remains substantially fixed. A thermocouple within at least one of the sample packings controls the uniform increase of temperature in the first hot zone, reducing the added heat immediately when an exothermic condition is sensed within the sample. Oxidized gases flow from outlets of the tubes to individual gas cells, and the gas flows through and out of the cells. The cells are sequentially periodically aligned with an infrared detector, which senses the composition and quantities of the gas components. Each elongated cell is tapered inward toward the center from cell windows at the end. Each cell contains a volume reduced from a conventional cell, while permitting maximum interaction of gas with the light beam. Reduced volume and angulation of the cell inlets provide rapid purgings of the cell, providing shorter cycles between detections. For coal and other high molecular weight samples, oxygen makes up from 50% to 100% of the gas introduced into the tubes.
This invention provides instruments and analysis equipment for a multi-sample by controlled-atmosphere programmed-temperature oxidation.
Before conception of the invention, a problem existed in determining whether sulfur was present in organic or inorganic compounds, for example in inorganic pyrite, which is iron disulfide. Exothermic reactions obscured results. The inventor experimented with gradually changing the oxygen concentration from 10% in argon to 16% in argon. A slight shift of the pyritic sulfur toward evolution at a higher temperature was noticed under those conditions. Continued increasing of the concentration to 20% and finally to 100% oxygen surprisingly improved results. The 100% oxygen experiment indicated that the pyritic sulfur evolution was moved to higher temperature and was evolved after the higher temperature organic sulfur peak, permitting both peaks to be resolved.
Further work showed that celite or other silica products such as silicic acid, silica gel, and synthetic silicas when used as diluents for the coal resulted in a more highly resolved pyrite evolution peak compared to tungsten trioxide, a previous diluent.
This invention provides use of the higher oxygen concentration ranges (50%-100%) and the use of tungsten trioxide, zirconium dioxide, silicon dioxide products, preferably celite, and other metal oxides as diluents. The invention also provides the use of metal oxides or other catalysts to oxidize organic compounds to oxides of carbon, hydrogen, sulfur and nitrogen. The metal oxides or other catalysts must not interact, absorb and re-emit, the oxide gases produced in the oxidation reaction.
The technique of the invention can be used to characterize coals, oilshales, carbon deposits on refinery and other catalysts, polymers, and other high molecular weight materials. In addition to the sulfur dioxide evolution profiles, the carbon dioxide, water, and nitrogen dioxide profiles are obtained. This allows characterization of the carbon, sulfur, hydrogen, and nitrogen in the material tested and analysis for those elements in the material.
The present invention is suited to resolve the gases evolved from the pyritic and the more oxidatively resistant organic sulfur in the material oxidized. The best conditions are produced in 100% oxygen with a silica product such as celite as a diluent for the material being oxidized. Preferably particle size of solids being oxidized and diluent are about −60 mesh or smaller. Preferably the diluent and the sample substance are well mixed and are uniformly distributed. However, high oxygen concentrations such as 50%-100% oxygen and other diluents such as silicic acid, silica gel, synthetic silicas, tungsten trioxide, zirconium dioxide, and other metal oxides may be used.
The technique is applicable to characterizing many substances, such as for example coals, treated coals, oil shales, polymers, carbon deposits on refinery and other catalysts, and other high molecular weight substances. The diluent or a screen may follow the sample. Preferably finely divided quartz wool previously heat treated at about 1100° C. is positioned upstream and downstream of the simple to hold the sample in position. Preferably quartz rods held in place by quartz wool are inserted in any void in the sample and catalyst tubes to reduce internal volume and promote flow-through of the evolved gases.
The invention evolves a material from the sample and oxidizes the evolved material.
When run in the oxidation mode, most of the oxidation occurs in the sample. The second tube and the catalyst complete the oxidation and establish SO
2
—SO
3
equilibrium.
Characterizing the substances under the oxidizing conditions described above is one of the objects of the invention. The evolved gas concentration versus time and/or temperature profiles for carbon dioxide, sulfur dioxide, nitrogen dioxide, and water are unique. Additionally, analyses for the amount of carbon, sulfur, nitrogen, and hydrogen in the sample oxidized are obtained by calculations based on the evolved gases.
The instrument can also be used in a pyrolysis mode where an inert gas is passed through the sample and diluent (silica product and/or metal oxides) with gradually increasing temperature. Gases are evolved from the sample and are oxidized by oxygen supplied to the gas stream as it enters the second hot zone. The gases produced, carbon dioxide, sulfur dioxide, nitrogen dioxide, and writer provide, after analysis, concentration versus time and/or temperature profiles for the pyrolysis gases produced from the substance being tested. Integrating the evolved gas profiles and relating them to the amount of carbon, hydrogen, sulfur, and nitrogen produced by pyrolysis with time data provides information similar to that of a thermal gravimetric analysis (TGA) experiment, in which samples are weighed as gases evolve. In addition, this provides information on the nature of the elemental composition of the volatile pyrolysis products.
A new multi-tube horizontal split combustion furnace made with two to six or more tubes has been designed and is incorporated into the system. A prototype version contains four combustion tubes and the temperature may be increased or ramped over a wide range of temperatures. However, 2° C. to
10
° C., and preferably 3° C. per minute are the preferred rates of increase. The furnace, mass flow controllers for the inlet gases, pressure transducers and regulation system, stepper motor for cell movement, and a number of relays
Creighton Wray James
Narasimhan Meera P.
Soderquist Arlen
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