Air pollution control system, air pollution control method, spray drying device of dewatering filtration fluid from desulfurization discharged water, and method thereof

Abstract

To include a boiler 11 that burns fuel F, an air heater 13 that recovers heat of flue gas 18 from the boiler 11 , a first precipitator 14 that reduces dust in the flue gas 18 after heat recovery, a desulfurizer 15 that reduces sulfur oxides in the flue gas 18 after dust reduction by an absorbent, a dewaterer 32 that reduces gypsum 31 from desulfurization discharged water 30 discharged from the desulfurizer 15 , a spray drying device 34 including an atomizer that atomizes a dewatering filtration fluid 33 discharged from the dewaterer 32 , and a flue-gas introducing line L 11 that introduces a part of the flue gas 18 into the spray drying device 34.

1 . A method for evaporating waste water and reducing harmful gas emissions, comprising:
 spraying waste water into flue gas to cool and moisturize the flue gas and dry solid contents within the waste water; and   separating the solid contents from the cooled and moisturized flue gas; and   adding at least activated carbon to the waste water prior to spraying the waste water into the flue gas.   
     
     
         2 . The method as set forth in  claim 1 , further comprising:
 removing at least mercury, boron and selenium from the waste water by a mercury removing unit using the activated carbon before spraying the waste water into the flue gas.   
     
     
         3 . The method as set forth in  claim 1 , further comprising:
 removing at least mercury, boron and selenium from the waste water by a mercury removing unit using a sulfide coagulation aid before spraying the waste water into the flue gas.   
     
     
         4 . The method as set forth in  claim 1 , further comprising:
 removing at least mercury, boron and selenium from the waste water by a mercury removing unit using a chelating agent or a crystallizer before spraying the waste water into the flue gas.   
     
     
         5 . The method as set forth in  claim 1 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using a reverse osmosis membrane before spraying the waste water into the flue gas.   
     
     
         6 . The method as set forth in  claim 1 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using an ion exchange membrane before spraying the waste water into the flue gas.   
     
     
         7 . The method as set forth in  claim 1 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         8 . The method as set forth in  claim 1 , further comprising:
 introducing a first part of the flue gas from a boiler to a spray drying device, the first part of the flue gas bypassing an air heater;   introducing a second part of the flue gas from the boiler to the air heater to heat combustion air by heat exchange with the second part of the flue gas and supplying the heated combustion air to the boiler;   mixing the cooled and moisturized first part of the flue gas with the second part of the flue gas after the second part of the flue gas has passed through the air heater and before the mixed first and second parts of the flue gas are passed to a precipitator for separating the solid contents from the cooled and moisturized flue gas.   
     
     
         9 . An air pollution control system, comprising:
 a boiler that burns fuel;   an air heater that recovers heat of flue gas from the boiler;   a first precipitator that reduces dust in the flue gas after heat recovery by the air heater;   a desulfurizer that reduces sulfur oxides in the flue gas after dust reduction by an absorbent;   a dewaterer that reduces gypsum from desulfurization discharged water discharged from the desulfurizer;   a spray drying device including an atomizer that atomizes a dewatering filtration fluid discharged from the dewaterer;   a flue-gas introducing line that introduces a part of the flue gas into the spray drying device; and   a waste-water treatment device that reduces harmful substances in a dewatering filtration fluid discharged from the dewaterer.   
     
     
         10 . The system as set forth in  claim 9 , further comprising:
 a mercury removing unit for removing at least mercury, boron and selenium from the waste water by adding an activated carbon to the waste water before spraying the waste water into the flue gas.   
     
     
         11 . The system as set forth in  claim 9 , further comprising:
 a mercury removing unit for removing at least mercury, boron and selenium from the waste water by adding a sulfide coagulation aid to the waste water before spraying the waste water into the flue gas.   
     
     
         12 . The system as set forth in  claim 9 , further comprising:
 a mercury removing unit for removing at least mercury, boron and selenium from the waste water by adding a chelating agent or a crystallizer to the waste water before spraying the waste water into the flue gas.   
     
     
         13 . The system as set forth in  claim 9 , further comprising:
 a halogen-ion removing unit having a reverse osmosis membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         14 . The system as set forth in  claim 9 , further comprising:
 a halogen-ion removing unit having an ion exchange membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         15 . The system as set forth in  claim 9 , further comprising:
 a halogen-ion removing unit for removing halogen ions from the waste water by using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         16 . The system as set forth in  claim 9 , wherein:
 the first precipitator connected to the spray drying device to receive at least the part of the flue gas from the spray drying device, the first precipitator configured to collect the dust from the flue gas and the desulfurizer connected to the first precipitator for receiving the flue gas and the desulfurizer reducing the sulfur oxides in the flue gas.   
     
     
         17 . The system as set forth in  claim 9 , wherein:
 the air heater is connected to the boiler and receives a first part of the flue gas from the boiler to heat combustion air by heat exchange with the first part of the flue gas and supplies the heated combustion air to the boiler;   the spray drying device receives a second part of the flue gas from the boiler, the second part of the flue gas, which is the part of the flue gas flowing through the flue-gas introducing line, bypasses the air heater; and   the spray device is connected to the first precipitator so that the first part of the flue gas is merged with the second part of the flue gas after the first part of the flue gas has passed through the air heater and before the merged first and second parts of the flue gas are supplied to the first precipitator.   
     
     
         18 . The method as set forth in  claim 2 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using a reverse osmosis membrane before spraying the waste water into the flue gas.   
     
     
         19 . The method as set forth in  claim 3 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using a reverse osmosis membrane before spraying the waste water into the flue gas.   
     
     
         20 . The method as set forth in  claim 4 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using a reverse osmosis membrane before spraying the waste water into the flue gas.   
     
     
         21 . The method as set forth in  claim 2 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using an ion exchange membrane before spraying the waste water into the flue gas.   
     
     
         22 . The method as set forth in  claim 3 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using an ion exchange membrane before spraying the waste water into the flue gas.   
     
     
         23 . The method as set forth in  claim 4 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using an ion exchange membrane before spraying the waste water into the flue gas.   
     
     
         24 . The method as set forth in  claim 2 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         25 . The method as set forth in  claim 3 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         26 . The method as set forth in  claim 4 , further comprising:
 removing halogen ions from the waste water by a halogen-ion removing unit using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         27 . The system as set forth in  claim 10 , further comprising:
 a halogen-ion removing unit having a reverse osmosis membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         28 . The system as set forth in  claim 11 , further comprising:
 a halogen-ion removing unit having a reverse osmosis membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         29 . The system as set forth in  claim 12 , further comprising:
 a halogen-ion removing unit having a reverse osmosis membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         30 . The system as set forth in  claim 10 , further comprising:
 a halogen-ion removing unit having an ion exchange membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         31 . The system as set forth in  claim 11 , further comprising:
 a halogen-ion removing unit having an ion exchange membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         32 . The system as set forth in  claim 12 , further comprising:
 a halogen-ion removing unit having an ion exchange membrane for removing halogen ions from the waste water prior to spraying the waste water into the flue gas.   
     
     
         33 . The system as set forth in  claim 10 , further comprising:
 a halogen-ion removing unit for removing halogen ions from the waste water by using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         34 . The system as set forth in  claim 11 , further comprising:
 a halogen-ion removing unit for removing halogen ions from the waste water by using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.   
     
     
         35 . The system as set forth in  claim 12 , further comprising:
 a halogen-ion removing unit for removing halogen ions from the waste water by using one of electrodialysis, a distilling unit and a crystallizer before spraying the waste water into the flue gas.