Extraction and air/water cooling system for large quantities of heavy ashes

Abstract

The present invention relates to an extraction and air/water cooling system and energy recovery for large flows of heavy ashes, produced by solid fuel boilers ( 100 ), able to reduce final temperature of the extracted ash, without increasing the air flow entering the throat of the boiler. When the air flow needed for cooling process exceeds the maximum flow admissible in the boiler, the system allows to the exceeding air and to the possible steam to be sent to the fume duct in the most appropriate point, thanks to a separation of the cooling environment made by the ash itself. The separation of the environments of the cooling system is handled automatically based upon a temperature signal of the ash at the system exhaust. If the cooling air is not sufficient to cool the ash, the cooling efficiency can be increased by adding atomized water. The added water flow usually is dosed based upon the ash flow and temperature so as to guarantee the full evaporation of the injected water in order to obtain at the exhaust, if necessary, dry ash suitable to be ground and transported pneumatically so as to be mixed to lighter ashes.

1 . A system for extracting, cooling and recovering energy of heavy ashes adapted to be used in association with a combustion chamber, the system comprising:
 (a) extraction and transport means for extracting and transporting heavy ashes coming from the combustion chamber;   (b) a cooling system for cooling the heavy ashes, located at said extraction and transport means and adapted to determine a feeding of cooling air at the extraction and transport means, wherein at least a portion of said cooling air is introduced into the combustion chamber from the bottom thereof;   (c) pressure insulation means adapted to determine a separation of the atmospheres between a first environment and a second environment of said extraction and transport means, said first environment being connected to the atmosphere of the combustion chamber and said second environment being connectable connected to the fume duct; and   (d) control means, adapted to determine activation of said pressure insulation of environments depending upon ash temperature and/or flow.   
     
     
         2 . The system according to  claim 1 , wherein said cooling system is a twofold air-water cooling system and said water cooling is activatable at said second environment. 
     
     
         3 .- 6 . (canceled) 
     
     
         7 . The system according to  claim 1 , wherein, under condition of pressure separation of environments, said cooling system is adapted to determine a feeding of cooling air in countercurrent with a flow of heavy ashes in said first environment and in equicurrent with said flow in said second environment. 
     
     
         8 .- 14 . (canceled) 
     
     
         15 . The system according to  claim 1 , wherein said control means is adapted to determine said separation of environments so that cooling air flow, entering the combustion chamber from the bottom, does not exceed a predetermined amount of total combustion air. 
     
     
         16 . The system according to  claim 15 , wherein said predetermined amount is equal to about 1.0-1.5%. 
     
     
         17 . The system according to  claim 1 , further comprising feeding means for feeding cooling air and a possible steam deriving from the cooling water into a combustion fume duct associated with the combustion chamber, wherein said feeding means are adapted to connect the combustion chamber with the second environment, substantially downstream of the cooling process. 
     
     
         18 . (canceled) 
     
     
         19 . The system according to  claim 17 , wherein said feeding means reach said fume duct at an economizers' area. 
     
     
         20 . The system according to  claim 17 , wherein said feeding means for feeding cooling air into the fume duct outlet upstream of an air/fume exchanger adapted to pre-heat combustion air. 
     
     
         21 . (canceled) 
     
     
         22 . The system according to  claim 17 , wherein said pressure insulation means comprise interdicting or enabling means for interdicting or enabling said feeding means for feeding into the fume duct, the interdicting or enabling means being controlled by said control means in order to determine said environment separation when needed. 
     
     
         23 .- 24 . (canceled) 
     
     
         25 . The system according to  claim 1 , wherein said extraction and transport means comprise a first extraction unit adapted to be located immediately downstream of the combustion chamber, and a second transport unit located downstream of said first unit, wherein said pressure insulation means are adapted to produce a pressure separation between said first extraction unit and said second transport unit. 
     
     
         26 .- 27 . (canceled) 
     
     
         28 . The system according to  claim 1 , wherein said pressure insulation means comprise means adapted to create a head of heavy
 ashes between said two environments, adapted to determine said pressure separation thereof.   
     
     
         29 . The system according to  claim 28 , wherein said pressure insulation means comprise a storage reservoir means adapted to receive heavy ashes creating said head. 
     
     
         30 . The system according to  claim 29 , wherein said pressure insulation means comprise a hopper adapted to receive heavy ashes creating said head. 
     
     
         31 . The system according to  claim 28 , wherein said control means comprise one or more level sensors arranged at said head. 
     
     
         32 . The system according to  claim 1 , further comprising a crusher of heavy ashes, located at said extraction and transport means. 
     
     
         33 . (canceled) 
     
     
         34 . The system according to  claim 28 , wherein said means, adapted to create an insulation head, are adapted to determine formation of said head immediately downstream of a crusher of heavy ashes, located at said extraction and transport means. 
     
     
         35 .- 44 . (canceled) 
     
     
         45 . The system according to  claim 1 , further comprising a duct for feeding hot air from said combustion chamber to a unit of said extraction and transport means contained in said second environment. 
     
     
         46 . A method for extracting and cooling heavy ashes coming from a combustion chamber, the method comprising:
 (a) extracting the heavy ashes from the combustion chamber;   (b) cooling the heavy ashes along an extraction and transport path by feeding cooling air along the path, introducing, downstream of a cooling process, at least part of said air into the combustion chamber from the bottom thereof; and   (c) depending upon temperature and/or flow of the heavy ashes, selectively activating a pressure insulation between a first environment and a second environment located along said extraction and transport path, said first environment being located immediately downstream of the combustion chamber and said second environment being located downstream of said first environment.   
     
     
         47 . The method according to  claim 46 , wherein said cooling (b) is a twofold air-water cooling and said cooling (b) provides activation of water cooling depending upon temperature and/or quantity of the heavy ashes. 
     
     
         48 . (canceled) 
     
     
         49 . The method according to  claim 47 , wherein said cooling (b) provides regulation of cooling water dispensing so that the cooling water wholly vaporizes during the cooling process, and substantially dray ashes are obtained at the exhaust of said extraction and transport path. 
     
     
         50 . The method according to  claim 47 , wherein said cooling (b) provides an activation of the water cooling at said second environment. 
     
     
         51 . (canceled) 
     
     
         52 . The method according to  claim 46 , wherein said cooling (b) provides, under said condition of pressure separation of environments, a feeding of cooling air in countercurrent with a flow of heavy ashes in said first environment and in equicurrent with said flow in said second environment. 
     
     
         53 .- 57 . (canceled) 
     
     
         58 . The method according to  claim 46 , wherein said activating (c) provides that said environment separation is carried out so that cooling air flow entering the combustion chamber from the bottom does not exceed a predetermined amount of total combustion air. 
     
     
         59 . The method according to  claim 58 , wherein said predetermined amount is equal to about 1.0-1.5%. 
     
     
         60 . The method according to  claim 46 , further comprising providing a feeding of cooling air and possible steam deriving from the cooling water into a combustion fume duct associated with the combustion chamber, wherein said feeding into the fume duct takes place starting from said second environment, substantially downstream of the cooling process. 
     
     
         61 . (canceled) 
     
     
         62 . The method according to  claim 60 , wherein said feeding into the fume duct provides an outflow in the latter at an economizers' area. 
     
     
         63 . The method according to  claim 60 , wherein said feeding into the fume duct provides an outflow into the fume duct upstream of an air/fume exchanger adapted to to pre-heat the combustion air. 
     
     
         64 . (canceled) 
     
     
         65 . The method according to  claim 60 , wherein said activating (c) provides that said pressure insulation be obtained through interdiction or enabling of said feeding of cooling air into the fume duct. 
     
     
         66 . (canceled) 
     
     
         67 . The method according to  claim 46 , wherein said extraction and transport path comprises a first extraction portion arranged immediately downstream of the combustion chamber and a second transport portion arranged downstream of said first portion and wherein said activating (c) provides that said pressure insulation is obtained between said first extraction portion and said second transport portion. 
     
     
         68 .- 69 . (canceled) 
     
     
         70 . The method according to  claim 46 , wherein said cooling (c) provides the creation of a head of heavy ashes between said two environments, adapted to determine said pressure separation thereof. 
     
     
         71 . The method according to  claim 70 , wherein said cooling (c) provides level detection of said head. 
     
     
         72 . The method according to  claim 46 , further comprising providing a crushing of heavy ashes, performed within said extraction and transport path. 
     
     
         73 . The method according to  claim 72 , wherein said crushing is performed between said first environment and said second environment. 
     
     
         74 .- 80 . (canceled) 
     
     
         81 . The method according to  claim 46 , further comprising providing a feeding of hot air from the combustion chamber to a portion of said extraction and transport path contained in said second environment.