Systems and methods for controlling the activity of carbon in heat treating atmospheres
AssigneeFurnace Control Corp.
InventorsRobert N. Blumenthal, Andreas T. Melville
Life of this patent
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Abstract
Systems and methods monitor the activity of carbon in a heat treating atmosphere, e.g., where a two phase region is desired for spherodize annealing. The systems and methods generate a computed activity of carbon value for the gas atmosphere as a function of temperature, partial pressure of oxygen, and carbon monoxide content of the gas atmosphere, and without determining a carbon dioxide content of the gas atmosphere. The systems and methods can make use of the computed activity of carbon value, e.g., to control the gas atmosphere.
Claims42
A device for monitoring activity of carbon in a heat treating atmosphere comprising
- a processor to generate a computed activity of carbon value for the gas atmosphere as a function of temperature, partial pressure of oxygen, and carbon monoxide content of the gas atmosphere, and without determining a carbon dioxide content of the gas atmosphere, and
- an output terminal coupled to the processor to output the computed activity of carbon value.
A system for monitoring a gas heat treating atmosphere comprising
- a processing element to derive a process variable indicative of an activity of carbon value for the gas atmosphere derived from at least one sensor placed in situ in the gas atmosphere, and
- an output for the process variable.
A spherodize annealing system comprising
- a heat treating furnace,
- an atmosphere source for supplying a preselected gas atmosphere to the furnace,
- a heat source to maintain the preselected gas atmosphere inside the furnace at a preselected temperature,
- an oxygen sensor located in situ in the furnace in contact with the preselected gas atmosphere, the oxygen sensor providing a first electrical input that varies according to oxygen content of the preselected atmosphere,
- a temperature sensor located in situ in the furnace in contact with the preselected gas atmosphere, the temperature sensor providing a second electrical input that varies according to temperature of the preselected atmosphere,
- a processor to generate a computed activity of carbon value for the preselected atmosphere as a function of the first and second electrical inputs.
A spherodize annealing system comprising
- a heat treating furnace,
- an atmosphere source for generating a preselected gas atmosphere and supplying the preselected gas atmosphere to the furnace,
- a heat source to heat the preselected gas atmosphere sufficiently to create a two phase region inside the furnace,
- a processor to generate a computed activity of carbon value for the gas atmosphere as a function of temperature, partial pressure of oxygen, and carbon monoxide content of the gas atmosphere, and without determining a carbon dioxide content of the gas atmosphere,
- an output terminal coupled to the processor to output the computed activity of carbon value, and
- a controller coupled to the output terminal and the atmosphere source to control generation of the gas atmosphere according to the computed activity of carbon value.
A method for monitoring a heat treating atmosphere comprising the steps of
- generating a computed activity of carbon value of the heat treating atmosphere as a function of temperature, partial pressure of oxygen, and carbon monoxide content of the heat treating atmosphere, and without determining a carbon dioxide content of the heat treating atmosphere, and
- using the computed activity of carbon value.
A method for monitoring a heat treating atmosphere comprising the steps of
- deriving from at least one sensor placed in situ in the heat treating atmosphere a process variable indicative of the activity of carbon in the heat treating atmosphere, and
- using the process variable.
A method for performing spherodize annealing comprising the steps of
- generating a gas atmosphere and supplying the gas atmosphere to a furnace,
- heating the gas atmosphere in the furnace sufficiently to create a two phase region,
- generating a computed activity of carbon value for the gas atmosphere as a function of temperature, partial pressure of oxygen, and carbon monoxide content of the gas atmosphere, and without determining a carbon dioxide content of the gas atmosphere, and
- controlling the gas atmosphere according to the computed activity of carbon value.
A method for performing spherodize annealing comprising the steps of
- generating a gas atmosphere and supplying the gas atmosphere to a furnace,
- heating the gas atmosphere in the furnace sufficiently to create a two phase region,
- sensing oxygen content with an oxygen sensor placed in situ in the furnace to provide a first electrical output that varies according to oxygen content of the gas atmosphere,
- sensing temperature with a temperature sensor placed in situ in the furnace to provide a second electrical output that varies with temperature,
- computing an activity of carbon value based upon the first and second electrical outputs, and
- controlling the gas atmosphere according to the computed activity of carbon value.
A method for determining a partial pressure of carbon monoxide in a gas atmosphere comprising a mixture of nitrogen and either an endothermic atmosphere or methanol, the method comprising the steps of
- supplying the gas atmosphere at a fixed flow rate into a furnace,
- deriving from an oxygen sensor placed in situ in the furnace a sensed partial pressure of oxygen in the furnace,
- deriving from a temperature sensor placed in situ in the furnace a sensed temperature in the furnace,
- deriving, without using a carbon monoxide sensor outside the furnace, a partial pressure of carbon monoxide as a function of the sensed partial pressure of oxygen and the sensed temperature.
Dependencies are inferred from the claim text.