Cement clinker production system and cement clinker production method

A cement clinker producing system, comprising:

• a cyclone preheater comprising two or more cyclone heat exchangers configured to preheat a cement clinker raw material;
• a rotary kiln configured to burn the cement clinker raw material preheated in the cyclone preheater so as to provide cement clinker;
• a calcination furnace comprising a heater, which is disposed together with the cyclone preheater on a front stream side of the rotary kiln, and is configured to promote decarbonation of the cement clinker raw material with use of the heater;
• a clinker cooler, which is disposed on a rear stream side of the rotary kiln, and is configured to cool the cement clinker;
• and a kiln exhaust-gas discharge passage configured to discharge an exhaust gas generated in the rotary kiln after the exhaust gas passes through the cyclone preheater;
• a combustion-supporting gas supply configured to supply a combustion-supporting gas having a higher oxygen concentration than an oxygen concentration of air;
• a combustion-supporting gas supply passage configured to guide the combustion-supporting gas from the combustion-supporting gas supply to the calcination furnace;
• a calcination furnace exhaust-gas discharge passage, which is different from the kiln exhaust-gas discharge passage, configured to discharge a carbon dioxide gas-containing exhaust gas generated in the calcination furnace;
• a preheated raw-material supply passage configured to supply the preheated cement clinker raw material from the cyclone preheater to the calcination furnace;
• a first recovery collector, which is disposed in the calcination furnace exhaust-gas discharge passage, and is configured to recover a quicklime-containing raw material from the carbon dioxide gas-containing exhaust gas;
• a calcination furnace exhaust-gas supply passage, which is coupled to the calcination furnace exhaust-gas discharge passage at a position on a rear stream side of the first recovery collector in the calcination furnace exhaust-gas discharge passage, and is configured to merge a part of the carbon dioxide gas-containing exhaust gas flowing through the calcination furnace exhaust-gas discharge passage into the combustion-supporting gas flowing through the combustion-supporting gas supply passage;
• a quicklime-containing raw material supply passage configured to supply the quicklime-containing raw material recovered by the first recovery collector from the first recovery collector to the cyclone heat exchanger coupled to the preheated raw-material supply passage or a cyclone heat exchanger located on a front stream side of the cyclone heat exchanger in the two or more cyclone heat exchangers;
• a first decarbonated raw-material supply passage configured to supply the cement clinker raw material decarbonated in the calcination furnace from the calcination furnace to the rotary kiln;
• a second decarbonated raw-material supply passage configured to supply a part of the decarbonated cement clinker raw material from the first decarbonated raw-material supply passage to a cyclone heat exchanger located on a rearmost stream side in the two or more cyclone heat exchangers;
• a temperature measurement device configured to measure a temperature of the exhaust gas in the kiln exhaust-gas discharge passage when the exhaust gas passes through the cyclone heat exchanger coupled to the preheated raw-material supply passage;
• and
• a decarbonated raw-material supply amount controller configured to adjust an amount of the decarbonated cement clinker raw material to be supplied from the second decarbonated raw-material supply passage to the cyclone heat exchanger located on the rearmost stream side based on the temperature measured by the temperature measurement device and adjust a temperature in the cyclone heat exchanger coupled to the preheated raw-material supply passage through the adjustment of the amount of the decarbonated cement clinker raw material,
• wherein the combustion-supporting gas supply passage is for heat exchange between the carbon dioxide gas-containing exhaust gas flowing through the calcination furnace exhaust-gas discharge passage and the combustion-supporting gas at a position on a front stream side of the first recovery collector in the calcination furnace exhaust-gas discharge passage, and
• wherein the preheated raw-material supply passage is coupled to any one of second to subsequent cyclone heat exchangers from a rearmost stream side in the two or more cyclone heat exchangers of the cyclone preheater.