Leco Corporation

Roger L Bredeweg

George J Sitek

Larry S O'Brien

Charles B Vallance

Ramsey G Reed

Edward P Povilaitis

The specification discloses an analyzer for determining the carbon, hydrogen, and nitrogen content of an organic material. The analyzer includes a vertically oriented, U-shaped furnace including a combustion chamber containing a crucible in which the sample is combusted into constituent gases and a reagent chamber containing a reagent through which the constituent gases must pass. A lance extends into the combustion chamber to guide the sample into the crucible and to direct oxygen onto the sample combusting in the crucible. The analyzer further includes an equilibration vessel and means for conveying the constituent gases to the vessel and past CO.sub.2 and H.sub.2 O infrared cells to monitor the products of combustion. Means are provided for conveying the equilibrated gases past the infrared cells to obtain readings relating to carbon and hydrogen content. A doser doses an aliquot of the equilibrated gas into a nitrogen measurement apparatus to obtain a reading relating to nitrogen content.

Carbon, hydrogen, and nitrogen 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 sample loading mechanism includes a hopper mounted to a base for positioning the hopper with respect to a furnace for releasably holding a relatively small sample in relation to a crucible used with the furnace. The hopper includes a floor with a movable element for alternately closing the floor for holding the sample and opening the floor permitting the sample to drop into the crucible. A plate is slideably mounted to the base above the hopper and includes an aperture which aligns with the hopper in a first position for admitting a sample to the hopper and is slideable to a second position for selectively sealing the upper end of the hopper. An actuator is provided for selectively controlling the movable element of the hopper for dropping the sample into a crucible aligned below the hopper.

Sample loading mechanism

A crucible assembly for use in an analytical furnace for the fusion of a sample includes a graphite heating crucible of cylindrical construction having one end open and an enclosed lower end with a positioning member interior to the interior cylindrical wall for receiving and positioning a separate sample holding crucible of cylindrical construction having an open upper end and an enclosed lower end. The heating crucible has an annular upper contact surface for engaging a first electrode and an annular lower contact surface for engaging a second electrode and positions the sample holding crucible in the zone of maximum heat in spaced relationship from the opposite ends of the heating crucible.

Crucible assembly

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

A combustion system includes a cylindrical horizontally extending ceramic combustion tube positioned in a furnace. The combustion tube is enclosed at one end and open at the opposite end for receiving a combustion boat carrying a sample to be combusted for subsequent analysis. The tube also receives a support block loosely positioned along the bottom of the tube and contacting the enclosed end for centering the combustion boat and for supporting one end of a sample withdrawal tube with an open end extending in the space surrounding the combustion boat and having an opposite end extending from the combustion tube. A lance tube also extends into the combustion tube for directing the flow of an oxidizing gas such as oxygen into the combustion boat to facilitate oxidation of a sample. The open end of the combustion tube is effectively sealed by a curtain of gas supplied by a flood tube having a plurality of longitudinally and angularly spaced slots and supplied with a suitable gas for blocking the open end of the tube from admission of atmospheric contaminants and preventing the escape of gasses from the combusted sample.

Combustion system

A system for stepwise advancing a row of crucibles individually through a loading station of an induction furnace includes a plurality of articulated fingers for gripping each of the crucibles. The fingers are mounted to a first slide for movement along the direction of advancement of the crucibles. The first slide is mounted to a second slide for advancing and retracting the fingers into crucible engaging and disengaging positions, respectively. Control means are provided for controlling the movement of the slides and the articulated fingers sequentially to stepwise advance the crucibles through the loading station.

Crucible loading-unloading system

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

A combustion system includes a combustion furnace for combusting a solid or liquid specimen and converting it to a gaseous mixture. The furnace is positioned in a circulatory loop in which oxygen is introduced to complete the combustion of the specimen into a gaseous mixture which is circulated through the furnace to fully oxidize the specimen and maintain the specimen gas concentration level constant during a measurement interval. To facilitate circulation of the gases in the loop, a circulation pump is employed in the flow path. In one embodiment, a detector is included in the loop while in alternative embodiments, an aliquot of the specimen gases is removed for analysis by a detector outside of the loop.

Growing community of inventors

Stevensville, MI, United States of America

Roger L Bredeweg