Analytical furnace with predictive temperature control
AssigneeLeco Corporation
InventorPeter M. Willis
Life of this patent
Estimating the term…
Abstract
An analytical furnace includes a predictive temperature control which is trained to model crucible temperature during analysis by employing a pair of temperature sensors, with one sensor being mounted in the furnace in fixed relationship and a second sensor which can be positioned within a crucible for training and tuning a crucible temperature profile, such that the crucible temperature in which a sample is placed is modeled and its response to the application of energy to the furnace in accordance with the furnace's dynamic thermal characteristics is known. By modeling the temperature profile within a crucible, the furnace can be controlled to provide a faster, more accurate analysis and prevent excessive overshooting of temperature as desired temperature plateaus are approached.
Claims15
An analytical furnace comprising:
- a combustion furnace having a generally disk-shaped body with a cylindrical side wall;
- a resistive heating element positioned within said side wall and extending around said furnace;
- a crucible-holding platter positioned within said furnace and having a plurality of apertures therein;
- a plurality of crucibles positioned within said apertures of said platter, wherein said crucibles hold samples for combustion within said furnace;
- a control circuit for controlling the application of power to said heating element;
- a first temperature sensor positioned in fixed relationship within said furnace for detecting the furnace temperature at said fixed location;
- a second temperature sensor removably positionable within one of said crucibles positioned on said platter;
- and
- wherein said control circuit includes a temperature modeling cycle for correlating the temperature between said first and second temperature sensors during a cycle of furnace temperature steps and developing in response thereto optimum temperature control signals for increasing crucible temperatures to desired temperature levels.
A thermogravametric analyzer comprising:
- a combustion furnace having a generally disk-shaped body including a cylindrical side wall;
- a resistive heater positioned within said side wall and extending around said furnace;
- a crucible-holding platter positioned within said furnace and having a plurality of apertures therein;
- a plurality of crucibles positioned within said apertures of said platter, wherein said crucibles hold samples for combustion within said furnace;
- first and second temperature sensors;
- and
- a control circuit for controlling the application of power to said heating element, wherein said control, circuit includes a processor which is programmed to measure the temperatures from said first temperature sensor which is positioned in fixed relationship within said furnace for detecting the furnace temperature at said fixed location and said second temperature sensor removably positionable within a crucible positioned on said platter, said control circuit modeling the crucible temperature profile as a function of detected furnace temperatures using a proportional, integral, and derivative (PID) process applied to temperature data obtained from said first and second temperature sensors.
A thermogravametric analyzer comprising:
- a furnace having a cylindrical sidewall;
- a balance with a weigh platform positioned within said furnace;
- a plurality of crucibles for holding samples for analysis;
- a rotatable support for holding said plurality of crucibles wherein said support is rotated to sequentially position crucibles on said weigh platform;
- a heater within said cylindrical sidewall for heating said furnace;
- a pair of temperature sensors including a first temperature sensor positioned in fixed relationship within said furnace and a second temperature sensor movable to be positioned within a crucible on said support;
- and
- a control circuit coupled to said temperature sensors, said circuit including a processor programmed to obtain temperature data to model the crucible temperature as the furnace temperature is varied and to subsequently control the furnace temperature during operation.
A thermogravametric analyzer comprising:
- a disk-shaped furnace having a heating element;
- a control circuit for controlling the application of power to said heating element;
- a crucible-holding platter including a plurality of apertures for holding sample-holding crucibles;
- a first temperature sensor positioned in fixed relationship within said furnace for detecting the furnace temperature at said fixed location;
- a second temperature sensor removably positionable within a crucible positioned on said platter within said furnace;
- and
- wherein said control circuit includes a temperature modeling cycle for correlating the temperature between said first and second temperature sensors during a cycle of step-wise increasing furnace temperature steps and developing in response thereto optimum temperature control signals for raising crucible temperatures to desired temperature levels while minimizing temperature overshoot.
Dependencies are inferred from the claim text.