Method and apparatus for rapid determination of the presence of carbon amounts

摘要

1, 043, 057. Determination of carbon. LABORATORY EQUIPMENT CORPORATION. Dec. 14, 1964 [Jan. 9, 1964], No. 50758/64. Heading B1X. [Also in Division G1] Carbon in an oxidizable material is determined by burning a sample of the material in oxygen, transporting the gaseous products of combustion mixed with excess oxygen through a purifying train for removing from the mixture components other than carbon oxides and oxygen and for converting carbon monoxide to carbon dioxide, and therefrom into the lower end of an analyses chamber beneath a vertically displaceable wall to raise the wall off the bottom of the chamber, collecting a predetermined volume of the carbon dioxide/ oxygen mixture below the raised wall at predetermined pressure and temperature and determining the carbon dioxide content of that volume of the mixture. The apparatus comprises a vertical tubular analysis chamber having therein a close fitting freely movable piston adapted to float on a column of gas within the chamber, an inlet to the chamber below the lowest position of the piston, a combustion chamber having an entry for the supply of oxygen thereto and an outlet for the products of combustion, between the outlets from the combustion chamber and the entry to the analysis chamber a purifying train, means for determining when the piston has risen to a predetermined height and means for sensing the carbon dioxide content of the gaseous mixture below the piston at that height. In the embodiment described in relation to the drawings, the sample (which may be steel, iron or other metal, coal, oil or carbides) is burnt in induction furnace 42 in a stream of oxygen from source 12. The analysis chamber 34 is previously swept out with oxygen from the top downwards to drive aluminium piston 128 (Fig. 2 not shown) to the bottom of the chamber. When the carbon dioxide-oxygen mixture emerging from purification train 46, 48, 50 passes into the analysis chamber through a restricted orifice (to improve mixing) at its bottom end, the piston rises in the chamber until it intercepts a beam of light actuating a photo-cell which shuts off the flow of oxygen from source 12. The carbon dioxide content of the gas mixture is measured using a bridge circuit which includes thermistors 118, 120 set in block assembly 108 mounted on glass tube analysis chamber 34 over a window 82 in the chamber (Fig. 4 not shown) thermistor 118 being exposed to the inside of chamber 34 and thermistor 120 being the reference thermistor. Fig. 7 (not shown) is a diagram of the electrical circuitry used in automatic operation of the apparatus.