Electrolysis: processes – compositions used therein – and methods – Electrolytic analysis or testing – For oxygen or oxygen containing compound
Reexamination Certificate
1999-10-05
2001-08-21
Warden, Sr., Robert J. (Department: 1744)
Electrolysis: processes, compositions used therein, and methods
Electrolytic analysis or testing
For oxygen or oxygen containing compound
C204S424000, C204S429000, C431S076000
Reexamination Certificate
active
06277268
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel gas sensors that may be used in conjunction with boilers, furnaces, or other combustors.
2. Discussion of Related Art
In numerous industrial environments, a hydrocarbon fuel is burned in a combustor (e.g., a boiler or furnace) to produce heat to raise the temperature of a fluid. The fluid may, for example, be water which is heated to generate steam to drive a turbine generator that provides power. Such industrial combustors typically employ an array of many individual burner elements to combust the fuel. In these combustors, various post-flame combustion control systems, such as overfire air, staging air, reburning systems, and selective non-catalytic reduction systems, can be employed in the post-flame zone to enhance the efficiency of the combustor. For the combustor to operate efficiently and to produce an acceptably complete combustion having byproducts that fall within the limits imposed by environmental regulations and design constraints, all of the individual burners should be operating cleanly and efficiently, and all post-flame combustion control systems should be properly balanced and adjusted.
Emissions of unburned carbon, nitrous oxides, carbon monoxide or other byproducts commonly are monitored to ensure compliance with environmental regulations. The monitoring of emissions heretofore has been done, by necessity, on the aggregate emissions from the combustor (i.e., the entire burner array—taken as a whole). Some emissions, such as the concentration of gaseous combustibles in hot flue gases, are difficult and/or expensive to monitor on-line and continuously. These emissions are typically measured on a periodic or occasional basis. When a particular combustion byproduct is found to be produced at unacceptably high concentrations, the combustor should be adjusted to restore proper operations. However, measurement of aggregate emissions, or measurement of emissions on a periodic or occasional basis, provides little, if any, useful information regarding what particular combustor parameters should be changed to effect such an adjustment.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a Nernstian-type gas sensor includes a mass of solid-electrolyte material, and first and second electrodes. The first and second electrodes are disposed on the mass of solid-electrolyte material to generate a signal therebetween indicative of a difference between an oxygen concentration at the first electrode and an oxygen concentration at the second electrode. Each of the first and second electrodes is in fluid communication with the environment.
According to another aspect of the invention, a method for monitoring changes in a concentration of oxygen present in an environment includes providing at least one Nernstian-type gas sensor including a mass of solid-electrolyte material, and at least first and second electrodes. Each of the first and second electrodes is disposed on the mass of solid-electrolyte material and is in fluid communication with the environment. A signal is generated between the at least first and second electrodes in response to changes in the concentration of oxygen in the environment.
According to another aspect of the invention, an apparatus for monitoring changes in a concentration of gas molecules of at least a first type in an environment includes a mass of material and first and second electrodes. The mass of material is permeable to ions formed when gas molecules of the first type are ionized. The first and second electrodes are arranged on the mass of material such that, when a concentration of the gas molecules of the first type at the first electrode is different than a concentration of the gas molecules of the first type at the second electrode, gas molecules of the first type are ionized at the first electrode to form ions which flow from the first electrode to the second electrode via the mass of material and are recombined at the second electrode to form gas molecules of the first type, thereby generating a signal between the first and second electrodes. Each of the first and second electrodes is in fluid communication with the environment.
According to another aspect of the invention, a method for monitoring changes in a concentration of gas molecules of at least a first type in an environment includes providing at least one Nernstian-type gas sensor including a mass of material that is permeable to ions formed when gas molecules of the first type are ionized, and at least first and second electrodes each arranged on the mass of material and each in fluid communication with the environment. A signal is generated between the at least first and second electrodes in response to changes in the concentration of the gas molecules of the first type in the environment.
According to another aspect of the invention, a Nernstian-type gas sensor includes a mass of solid-electrolyte material, and first and second electrodes. Each of the first and second electrodes is disposed on the mass of solid-electrolyte material to generate a signal therebetween indicative of a difference between an oxygen concentration at the first electrode and an oxygen concentration at the second electrode. The sensor is free of a temperature control device.
According to another aspect of the invention, a method for monitoring changes in a concentration of oxygen in an environment includes providing at least one Nernstian-type gas sensor including a mass of solid-electrolyte material and at least first and second electrodes disposed on the mass of solid-electrolyte material, wherein the at least one sensor is free of a temperature control device. A signal is generated between the at least first and second electrodes in response to changes in the concentration of oxygen in the environment.
According to another aspect of the invention, a method for calibrating a gas sensor includes supplying each of a first gas having a first profile and a second gas having a second profile, which is different that the first profile, to the gas sensor in a predetermined sequence. The gas sensor or a signal analyzer associated therewith is adjusted based upon an output signal of the gas sensor to calibrate the gas sensor.
According to another aspect of the invention, an apparatus for calibrating a gas sensor includes a switching system and a sequencer. The switching system is in fluid communication with each of a first tank having a first predetermined gas profile and a second tank having a second predetermined gas profile. The sequencer causes the switching system to supply gas from each of the first and second tanks to the gas sensor in a predetermined sequence.
According to another aspect of the invention, a method for calibrating a gas sensor includes supplying gas such that a concentration of molecules of at least a first type in the gas changes during a time interval. The gas supplied during the time interval is provided to the gas sensor so that the gas sensor generates a first signal in response to the change in the concentration of the first type of molecules in the gas during the time interval. The gas supplied during the time interval is also provided to a reference sensor so that the reference sensor generates a second signal in response to the change in the concentration of the first type of molecules in the gas during the time interval. At least one characteristic of the first signal is compared to at least one characteristic of the second signal, and the gas sensor or a signal analyzer associated therewith is adjusted based upon the comparison of the at least one characteristic of the first signal and the at least one characteristic of the second signal to calibrate the gas sensor.
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Ivantotov Alexander A.
Khesin Mark J.
Olsen Kaj K.
Reuter-Stokes, Inc.
Warden, Sr. Robert J.
Wolf Greenfield & Sacks P.C.
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