Kiln plant control system
AssigneePretoria Portland Cement Company Limited
InventorsMichael John Kearns, Tony Brian Lange, Neville Frewin
Life of this patent
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Abstract
A controller for a kiln plant, typically a cement plant, has a thermodynamic controller which measures a number of variables including the kiln hood temperature and one or more output gas concentrations, and controls the fuel input to the kiln to maintain the hood temperature within a desired range and a main impeller of the kiln to maintain the measured gas concentrations within a predetermined range. The invention includes a quality controller wich controls the amount of 3CaO.SiO2 present in clinker produced by the plant. The controller comprises an inner controller which controls free-lime content in the clinker and a thermodynamic outer controller.
Claims19
A controller for a kiln plant comprising a kiln having a firing end and a back end, wherein fuel is combusted at the firing end and raw meal is fed into the back end for conversion to clinker in the kiln, the controller comprising:
- a first temperature sensor arranged to measure the temperature at or near the firing end of the kiln and to generate an output indicative of this temperature;
- gas sensing means arranged to measure the concentration in the kiln of at least one gas from the group comprising O2, NOX, SOX and CO and to generate at least one respective output indicative of the relevant gas concentration;
- and
- control means adapted to receive the output from the first temperature sensor and to control the amount of fuel fed to the firing end of the kiln to maintain the temperature at or near the hood of the kiln within a predetermined range, the control means being further adapted to receive said at least one output from the gas sensing means and to control at least a main impeller of the kiln to maintain the concentration of said at least one gas within a predetermined range,
- thereby to maintain a desired thermodynamic profile in the kiln to control and optimise the properties of clinker produced therein.
Control means for a kiln plant, the control means comprising an outer quality controller cascaded to at least one inner controller, wherein the outer quality controller comprises a first feedback controller being adapted to receive a first setpoint input indicating a desired amount of 3CaO.SiO2 and/or 2CaO.SiO2 to be present in clinker produced by the kiln plant, and a second feedback input indicating the actual amount of 3CaO.SiO2 and/or 2CaO.SiO2 present in clinker being produced by the kiln plant, the first feedback controller being further adapted to compare the first setpoint input and the second input and, if the inputs differ, to produce an output to alter a setpoint input to the inner controller directly or indirectly to adjust one or more of the kiln plant's operating parameters so that the amount of 3CaO.SiO2 and/or 2CaO.SiO2 in the clinker produced by the kiln plant will be substantially equal to the desired amount of 3CaO.SiO2 and/or 2CaO.SiO2 of the clinker.
Dependencies are inferred from the claim text.