Methods and systems for recovery of co2 gas in cement-manufacturing facilities, and processes for manufacturing cement

Abstract

An object of the present invention is to separate CO 2 gas generated in a cement-manufacturing facility in a high concentration and recover the CO 2 gas. The present invention includes: feeding a cement material before calcination and a heat medium which has a particle diameter larger than that of the cement material and has been heated to the calcination temperature or higher in a medium-heating furnace (14), to a mixing calciner (12); and recovering the CO 2 gas generated by the calcination of the cement material. The heat medium circulates between the medium-heating furnace and the mixing calciner. Another aspect of the present invention includes: feeding a cement material before calcination to a regenerative calciner (112) which has been heated to the calcination temperature or higher and has stored heat therein; and recovering the CO 2 gas generated by the calcination of the cement material.

1 . A process for manufacturing cement comprising preheating a cement material with a first preheater, feeding the preheated cement material to a cement kiln having an atmosphere in an inner part held at high temperature and firing the fed cement material, and further comprising recovering CO 2  gas generated by calcination of the cement material with a method for recovering CO 2  gas generated in a cement-manufacturing facility comprising:
 feeding a non-calcined cement material, which has been extracted from the first preheater, to a mixing calciner;   heating a heat medium, having a particle diameter larger than that of the cement material, to a calcination temperature or higher in a medium-heating furnace;   feeding the heat medium to the mixing calciner;   calcining the non-calcined cement material with the heat medium in the mixing calciner;   separating a cement material which has been calcined from the heat medium;   feeding the cement material which has been calcinedto a cement kiln;   returning the heat medium to the medium heating furnace and circulating the heat medium between the medium-heating furnace and the mixing calciner; and   recovering CO 2  gas generated by the calcining of the non-calcined cement material in the mixing calciner.   
     
     
         2 . A system for recovering CO 2  gas generated in a cement-manufacturing facility which is provided with a first preheater for preheating a cement material and a cement kiln for firing the cement material that has been preheated in the first preheater, comprising:
 an extraction line for extracting a non-calcined cement material from the first preheater;   a mixing calciner to which the non-calcined cement material that has been extracted from the extraction line is introduced;   a medium-heating furnace for heating a heat medium having a particle diameter larger than that of the non-calcined cement material, to a calcination temperature of the non-calcined cement material or higher;   a circulation line for feeding the heat medium which has been heated in the medium-heating furnace to the mixing calciner, and for returning the heat medium to the medium-heating furnace from the mixing calciner;   a return line for returning one part of the cement material which has been heated and calcined by the heat medium in the mixing calciner, to the first preheater or to a cement kiln; and   a CO 2  gas exhaust pipe for recovering CO 2  gas generated in the mixing calciner.   
     
     
         3 . The system of  claim 2 , further comprising:
 a second preheater which is provided independently from the first preheater and preheats another non-calcined cement material; and   a transfer pipe for feeding the another non-calcined cement material before calcination, which has been preheated in the second preheater, to the mixing calciner,   wherein the CO 2  gas exhaust pipe connected to the mixing calciner is a heating source of the second preheater.   
     
     
         4 . The system of  claim 2 , wherein the medium-heating furnace is a moving bed having a heating source in a lower part. 
     
     
         5 . A method for recovering CO 2  gas generated in a cement-manufacturing facility which preheats a cement material in a first preheater, then feeds the preheated cement material to a cement kiln having an atmosphere in an inner part held at high temperature and fires the fed cement material, comprising:
 feeding a non-calcined cement material, which has been extracted from a first preheater, to a regenerative calciner which has been heated to a calcination temperature or higher and has stored heat therein, and calcining the fed non-calcined cement material; feeding the cement material which has been calcined, to a cement kiln; and   recovering CO 2  gas generated by the calcining of the non-calcined cement material in a regenerative calciner.   
     
     
         6 . The method of  claim 5 , further comprising:
 providing a plurality of regenerative calciners;   heating at least one of the regenerative calciners to a calcination temperature or higher to store heat therein, while at least one of the other regenerative calciners calcines the cement material or alternately repeating the calcination and heat storage in the plurality of regenerative calciners; and   recovering CO 2  gas generated by the calcining of the non-calcined cement material.   
     
     
         7 . The method of  claim 5 , further comprising filling the regenerative calciner with a heat medium having a particle diameter larger than that of the non-calcined cement material. 
     
     
         8 . The method of  claim 7 , wherein the heat medium is at least one cement clinker obtained by firing the non-calcined cement material in the cement kiln, silica stone or quicklime. 
     
     
         9 . The method of  claim 5 , further comprising:
 feeding the non-calcined cement material, which has been extracted from the first preheater, and another non-calcined cement material, which has been preheated in a second preheater independent from the first preheater, to the regenerative calciner;   using CO 2  gas generated in the regenerative calciner as a heating source of the second preheater; and   recovering resultant CO 2  gas.   
     
     
         10 . The method of  claim 5 , further comprising:
 fluidizing the cement material with CO 2  gas generated when the non-calcined cement material is fed to the regenerative calciner and is calcined therein, thereby making the cement material which has been calcined overflow from the regenerative calciner; and   feeding the overflowing cement material to the cement kiln.   
     
     
         11 . The method of  claim 5 , further comprising:
 entraining the cement material with CO 2  gas generated when the non-calcined cement material is fed to the regenerative calciner and is calcined;   separating the cement material from the CO 2  gas; and   feeding the cement material which has been calcined to the cement kiln.   
     
     
         12 . The method of  claim 5 , further comprising:
 returning one part of the cement material which has been calcined in the regenerative calciner to the first preheater.   
     
     
         13 . The method of  claim 12 , further comprising:
 heat-exchanging one part of the cement material with air; returning the cement material which has cooled to the first preheater; and   feeding heated air as air for combustion in the regenerative calciner.   
     
     
         14 . A system for recovering CO 2  gas generated in a cement-manufacturing facility which is provided with a first preheater for preheating a cement material and a cement kiln for firing the cement material that has been preheated in the first preheater, comprising:
 an extraction line for extracting a non-calcined cement material from the first preheater;   a regenerative calciner to which the cement material that has been extracted from the extraction line is introduced and which heats the cement material to a calcination temperature of the non-calcined cement material or higher and stores heat therein;   a return line for returning one part of the cement material which has been calcined in the regenerative calciner, to the first preheater or a cement kiln; and   a CO 2 -gas exhaust pipe for recovering CO 2  gas generated in the regenerative calciner therethrough.   
     
     
         15 . The system of  claim 14 , further comprising:
 a second preheater which is provided independently from the first preheater and preheats another non-calcined cement material; and   a transfer pipe for feeding the another non-calcined cement material, which has been preheated in the second preheater, to the regenerative calciner, wherein CO 2  gas sent from the regenerative calciner is a heating source of the second preheater.   
     
     
         16 . The system of  claim 14 , wherein a plurality of the regenerative calciners are provided.