Reduced size fire tube boiler system and method of operating same

Abstract

A boiler system having a generally cylindrical housing or shell includes a main or fire tube with a furnace or combustion chamber extending longitudinally near the bottom of the housing and a burner to accomplish combustion within the combustion chamber. The combustion chamber opens at its rear end to furnace tube sheet, and to a first set of tubes extending longitudinally of the boiler. The first set of tubes extends to and through the rear tube sheet of the boiler to a turnaround space, which transitions to a second set of tubes located above the combustion chamber and first set of tubes to generally span a length extending from the rear tube sheet of the boiler to the front tube sheet. The boiler system as disclosed has a reduced size while maintaining efficiency in steam and hot water applications.

1 . A boiler system comprising:
 a burner;   a housing having a generally cylindrical shape and extending between first and second walls to provide a generally cylindrical space;   a fire tube positioned near a bottom of the generally cylindrical space the fire tube and extending longitudinally from a first wall of the cylindrical housing to a fire tube end wall, the fire tube providing a combustion chamber where combustion of an air-fuel mixture is accomplished using the burner;   a first set of tubes located within the housing and extending longitudinally from and parallel with the end of the fire tube to the second wall of the housing, and   a second set of tubes located above and about a portion of the fire tube and a portion of the first set of tubes, the second set of tubes generally spanning a length extending between the first and the second walls of the cylindrical housing; and   a chamber providing a space between and connecting the first and second sets of tubes; and   wherein heated combustion gases flow from the fire tube to the first set of tubes, through the chamber space, and to the second set of tubes.   
     
     
         2 . The boiler system of  claim 1 , wherein the fire tube includes a shell structure comprising a generally cylindrical shape having a circumference and the first set of tubes extends in-line with the fire tube. 
     
     
         3 . The boiler system of  claim 1 , wherein the housing includes a circumference and the second set of tubes extends at least partially about the shell structure. 
     
     
         4 . The boiler system of  claim 3 , wherein a vertical plane passing through a center of the housing also passes through a center of the fire tube and the first and second sets of tubes are each positioned generally symmetrically on either side of the vertical plane. 
     
     
         5 . The boiler system of  claim 4 , wherein at least one of: (a) none of the tubes of the second set of tubes extend in a region or location that is below any portion of the fire tube, and (b) none of the tubes of the second set of tubes extend in a region or location that is below any portion of the tubes of the first set of tubes. 
     
     
         6 . The boiler system of  claim 4 , wherein none of the tubes of the second set of tubes extend in a region or location that is between the fire tube and the bottom of the cylindrical housing. 
     
     
         7 . The boiler system of  claim 1 , wherein the flow of heated combustion gases is sequential such that the heated gases flow from the fire tube directly to and through the first set of tubes, and then directly to and through the chamber space, and then directly to and through the second set of tubes, before the heated combustion gases are discharged from the boiler. 
     
     
         8 . The boiler system of  claim 1 , wherein the second set of tubes the and the first set of tubes are submerged in water. 
     
     
         9 . The boiler system of  claim 8 , wherein either: (a) water is provided within the housing to a water level, providing open space to remain within the housing and permitting the boiler to be configured for steam applications; or (b) water is provided within the housing so that the housing is filled with water and the boiler is configured for hot water applications. 
     
     
         10 . The boiler system of  claim 1 , wherein either: (a) water is provided within the housing to a water level, providing space open space to remain within the housing and permitting the boiler to be configured for steam applications; or (b) water is provided within the housing so that the housing is filled with water and the boiler is configured for hot water applications. 
     
     
         11 . The boiler system of  claim 1 , wherein the first set of tubes comprises one or more plain tubes, one or more plain tubes with an extended heating surface, or one or more rifled tubes, and where in the second set of tubes comprises one or more plain tubes, one or more plain tubes with an extended heating surface, or one or more rifled tubes. 
     
     
         12 . The boiler system of  claim 1 , wherein the burner is integrated with respect to the fire tube. 
     
     
         13 . The boiler system of  claim 12 , wherein the burner is integrally formed with the housing. 
     
     
         14 . The boiler system of  claim 12 , wherein combustion of the air-fuel mixture is completed within the combustion chamber, which is the only combustion chamber. 
     
     
         15 . The boiler system of  claim 14 , wherein the air provided with for use with the air-fuel mixture is provided from a single source. 
     
     
         16 . The boiler system of  claim 1 , wherein there is no device provided within the chamber providing the space between and connecting the first and second sets of tubes, that is configured to close any portion or end of any of the tubes in the first set of tubes or any of the tubes in the second set of tubes. 
     
     
         17 . The boiler system of  claim 1 , wherein there is no device provided within the chamber providing the space between and connecting the first and second sets of tubes, that is configured to reverse the flow of any portion of the heated gases in any of the tubes in the first set of tubes, or any of the tubes in the second set of tubes.