1,052,333. Automatic process control. BUNKER-RAMO CORPORATION. April 21, 1964 [May 2, 1963], No. 16516/64. Heading G3R. In a rotary kiln for producing portland cement, a liquid slurry or dust, is fed through a hopper 22 and gravity fed into a pre-heater 24, and subsequently or directly, to an inclined reaction chamber 26 rotated by a motor 28 driving a gearring 32. At the exit end of a kiln a fuel supply line 34 is jointed by a primary air supply line 36 to form a fuel-air mining chamber 38 which injects a high velocity flame into the reaction chamber. The heated gases are withdrawn by a suction fan 42 exhausting through a stack 44. Near the flame 40 the major chemical reactions take place and the feed partially liquefies and reacts to form clinker and drops onto a moving grate 46 where it is cooled by a secondary air stream from a fan 48. A plurality of monitors are positioned at the input to the kiln including a hopper feed rate detector 50, a fan speedsensor 52, exit gas temperature and pressure sensors 54, 56, excess oxygen 58, and the amount of carbon dioxide 59. A plurality of thermocouples 60 sense the feed temperature along the kiln and an optical pyrometer 62 senses the temperature of the burning zone. In the hood 66 the pressure is sensed by a detector 68 and the air temperature by a device 64. The grate 46 is provided with a pressure detector 70; a speed detector 72 and the cooling air flow by a detector 74. The instrumentation is employed in a control system, comprising an update section, wherein control parameters are modified in dependence on change in kiln characteristics i. e., refractory lining, an optimising section wherein desired operating values, determined by management objectives, i.e. throughput or optimum efficiency, are fed to a model-programmed digital computer, together with the measured data; the predicted kiln operating parameter from the computer are fed to a regulate section wherein further modification are effected to derive controller set points for the plant apparatus.
