Leco Corporation

George J Sitek

Roger L Bredeweg

Charles W Berk

Richard B Haigh

Sherman L Walker

Robert N Revesz

The specification discloses a proximate analyzer for the analysis of fossil fuels such as coal and coke. The analyzer includes a temperature-controllable and atmosphere-controllable furnace chamber, a balance having a weigh platform positioned within the furnace chamber, and a platter positioned within the chamber and adapted to support a plurality of sample-containing crucibles. The furnace further includes means for continuously depositing the crucibles in a predetermined sequence on the weigh platform and means for monitoring the weights of the crucibles to determine when analysis is complete and for calculating the proximate analysis results based on weight loss. A method of proximate analysis using the proximate analyzer is also disclosed.

Proximate analyzer

An electrode assembly includes an electrode and a crucible-supporting insert releasably secured to the electrode. In the preferred embodiment a collar is threaded onto the electrode and has tabs extending inwardly to clamp the insert to the electrode. A small button-like projection on the electrode may be provided and is received within an aperture in the insert to center the insert on the electrode.

Furnace electrode

A control system for applying operating power to an analytical furnace includes a first circuit providing output signals consisting of a series of binary bits in a predetermined pattern with each bit corresponding to a unit of power to be applied to an analytical furnace according to the pattern of bits and a control circuit coupled to the first circuit and including output terminals for coupling the control circuit to an analytical furnace. The control circuit responds to the binary bits to provide pulses of operating power to the output terminals in a sequence corresponding to and controlled by the binary bits. The pattern of bits provides stepwise increasing temperature levels for the analytical furnace in a very predictable and controlled fashion such that samples combusted by the furnace will emit specimen gases associated with different compounds containing the specimen gas at different temperature levels.

Method and apparatus for controlling an analytical furnace

A calorimeter vessel includes a base for supporting a bomb thereon and a downwardly concavely opening container sealably engaging the base. The base includes a water supply system permitting a common water supply to supply water to three such vessels which include water level detecting sensors also permitting automatic filling of the vessels. In the preferred embodiment the vessel is filled in two stages providing rapid yet precise filling of each of the vessels. In one embodiment of the invention a microprocessor control circuit is employed for sampling temperature data within each of the vessels during an analysis to ascertain beginning and ending temperatures and for calculating the resultant heat of combustion of a sample. The microprocessor also is employed to automatically control the filling and emptying of the vessel and the firing of the sample containing calorimeter bomb.

Calorimeter

A combustion analyzer for the analysis of the carbon and sulfur content in steel includes a gas flow system whereby a carrier gas flows through a combustion chamber and gaseous by-products of combustion flow through one or more infrared cells for analysis. In order to correct for the inherent nonlinearity of the measurement of concentration by the infrared cell or cells, a linearity correction system is provided. In the linearity correction system, discrete levels of concentration of known gases are dosed into the system and the detected concentration measured. Scaling factors are determined by an iterative process employing a microprocessor which scaling factors are then employed to correct for the nonlinearity in sample measurements. In one embodiment of the invention, the flow of the specimen gas employed for dosing the system is measured as a function of the pressure differential across a given size flow restrictor using an improved control valve and dosing manifold.

Method and apparatus for gas dosing for linearization

For use in a combustion furnace for analytical apparatus in which a specimen is combusted in a combustion chamber and gases therefrom are withdrawn for analysis, a cleaning apparatus mounted at one end of the combustion chamber. The cleaning apparatus includes a housing sealably mounted to the combustion chamber and containing a movable cleaning element for abrading the interior walls of the combustion chamber. A shield is positioned between the cleaning element and the combustion chamber such that during combustion of a specimen, the cleaning element is effectively shielded from the high temperature combustion. In one embodiment, the housing also includes a filter between gas supply and exhaust passages and apparatus for self-cleaning of the filter.

Combustion chamber cleaning apparatus

An instrumentthat determines the HF and the HNO.sub.3 concentration or other mixed acids or single acid of an acid bath measures the potential difference between a fluoride ion selective electrode and a reference electrode and the potential difference between a hydrogen ion selective electrode and the reference electrode. The electrode voltages are applied to a control circuit including a microprocessing unit for calculating and displaying the acid concentrations of the bath and for compensating for the nonlinearity of the measured voltages as well as the interdependence of the two voltages. Also, means are provided for calculating and displaying percent metal concentrations.

Acid tester

An arc control circuit supplies voltage to an electrode of a portable analyzer for striking an arc against a specimen to provide an aerosol of the specimen material for analysis. The circuit includes a source of voltage and voltage dividing means for selectively applying different proportions of the source voltage to the electrode. Sensing means are coupled to the electrode for actuating bypass switching means coupled to the voltage dividing means when the electrode has made contact with the specimen to apply the full voltage of the power supply to the electrode to start the arc. As the electrode tip is withdrawn from the sample a predetermined distance, the desired arc is maintained. Means are provided for quenching the arc by opening the bypass switch to lower the electrode voltage once the arc has been maintained for a desired amount of time.

Arc control circuit

A resistance heating furnace employs a pair of spaced electrodes, one of which is movable to clamp a resistive crucible between the electrodes for passing current therethrough for heating a specimen positioned in the crucible to fuse the specimen. A passageway is provided through one of the electrodes to permit an inert carrier gas to remove gases from the crucible for subsequent analysis. The electrode construction includes a relatively highly conductive base material electrically coupled to a power source for actuating the electrodes and inserts coupled to the surfaces of the electrodes which engage the resistive crucible. The insert material has a relatively high melting point and hardness and a relatively high thermal and electrical conductivity to increase the heating of the crucible and improve the durability of the electrodes. At least one of the electrodes is movable and actuated by a fluid cylinder for clamping the crucible between the electrodes at a constant pressure regardless of the crucible length.

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Stevensville, MI, United States of America

George J Sitek