GB871027A - Improvements in or relating to rotary tubular furnaces - Google Patents

Abstract

871,027. Automatic control systems for cement kilns. INSTITUT FUR WARMETECHNIK UND AUTOMATISIERUNG DER SILIKATHUTTENINDUSTRIE. Oct. 3, 1957 [Oct. 3, 1956], No. 31060/57. Class 38 (4). [Also in Group XII] In a rotary furnace having a travelling grate preheater, the amount of combustion air supplied is determined in accordance with the fuel supply and an empirically determined heat requirement, and the blowers controlling the passage of air and gases through the furnace are regulated in accordance with the volume of the exhaust gases. A voltage derived from the fuel supply meter 48 in series with a potentiometer 81 adjusted in accordance with oxygen content of the exhaust gases leaving the rotary kiln 20, Fig. 1, as measured at 65, and a voltage from the measurement at 33 of the empirically determined amount of combustion air in series with a potentiometer 80 adjusted to determine the relationship between the total air supplied by blower 29 past damper 31, are applied in parallel to a potentiometer 82. The amounts of primary and tertiary air measured at 42, 43 are controlled by regulators 83, 84 through dampers 44, 45 according to the tappings 85 in the potentiometer 82 which are adjusted in accordance with the length of the flame. Regulators 88, 89 for the volume of gas circulated between the preheating and drying chambers 2, 1 and the volume of gas delivered to the flue by blower 15 control dampers 14, 15a in accordance with tappings on the potentiometer 82 which are adjusted in accordance with pressure at the burner end 62 of the rotary kiln 20, which gives a measure of the amount of gas passing through the kiln, and the pressure difference between the preheating and drying chamber 2, 1 and the temperature in the drying chamber respectively. The volume of gas passing to the flue, measured at 16 also controls the damper 15a. The primary and tertiary air supplies are taken from above the grate in a first clinker cooling chamber 27, a second clinker cooling chamber 28 having a water spray 55 and a damper controlled outlet duct. The rate of travel of the preheater grate 7 is maintained in a constant ratio to the speed of rotation of the kiln 20, to maintain the level of material in the kiln. The rate at which fuel is supplied to the kiln may be varied by an industrial calorimeter.