Scotch marine style boiler with removable tube bundle

Abstract

A boiler includes a cylindrical shell sealed at both ends. A working liquid, typically water, circulates inside the shell. A tube bundle is seated inside the shell. Hot combustion gases circulate inside the tube bundle, heating the water circulating inside the shell. The tube bundle includes a relatively large inlet tube that runs straight to a distal end, where hot combustion gases are turned 180° by a concave inner surface on the tube bundle header, which is not a part of the shell, and are returned by a plurality of smaller diameter return tubes and then to an exhaust stack. The tube bundle includes a front tube sheet and a distal end tube sheet that the tubes are welded to, but these tube sheets are not part of the shell. The entire tube bundle floats inside the shell without being fastened to the shell except at the front of the tube bundle, where a baffle is secured to the front opening of the shell. This allows the tube bundle to be removed from the shell as a single unit.

I claim:  
     
         1 . A boiler comprising: 
 a. a shell;    b. a tube bundle exchanger seated inside said shell, said tube bundle comprising one inlet tube adapted to direct combustion gases in one direction and at least one return tube in fluid communication with said inlet tube adapted to direct combustion gases in the opposite direction.    
     
     
         2 . A boiler in accordance with  claim 1  further comprising means for redirecting the flow of hot gases from said inlet tube 180° to pass through said return tube.  
     
     
         3 . A boiler in accordance with  claim 2  where in said gas redirecting means further comprises a tube-bundle dome having a concave interior surface, with said dome being fixed onto said distal end of said tube bundle, wherein said tube bundle dome is not part of said shell.  
     
     
         4 . A boiler in accordance with  claim 1  wherein said inlet tube and said at least one return tube are parallel to each other.  
     
     
         5 . A boiler in accordance with  claim 3 , wherein said tube bundle further comprises a distal end tube sheet that said tubes are fastened to and a front end tube sheet to which said inlet tube and said at least one return tube are fastened.  
     
     
         6 . A boiler in accordance with  claim 4  wherein said tube bundle comprises an integrated unit that is removable from shell.  
     
     
         7 . A boiler in accordance with  claim 5  further comprising means for installing or removing said tube bundle in said shell.  
     
     
         8 . A boiler in accordance with  claim 6  wherein said installation and removal means further comprises a pair of skid rails mounted on said heat exchanger and a pair of skid members mounted on a lower portion of an inside lower surface of said shell, whereby said tube bundle can be slid into or out of said shell.  
     
     
         9 . A boiler in accordance with  claim 7  further comprising means for sealing said tube bundle inside said shell.  
     
     
         10 . A boiler in accordance with  claim 6  wherein said tube bundle further comprises a plurality of spaced baffles, each said baffle having a plurality of apertures with said inlet tube and said at least one return tube passing through one said aperture of each baffle, with each said tube free to float within said apertures.  
     
     
         11 . A boiler comprising: 
 a. a shell;    b. a tube bundle exchanger seated inside said shell, said tube bundle comprising one inlet tube adapted to direct combustion gases in one direction and a plurality of return tubes in fluid communication with said inlet tube adapted to direct combustion gases in the opposite direction; and    c. means for inserting and removing said tube bundle from said shell.    
     
     
         12 . A boiler in accordance with  claim 11  wherein inserting and removing means further comprises a pair of spaced parallel skid rails fixed to a lower surface of said baffle and a pair of spaced parallel skid members fixed to a lower inner surface of said shell and said skid rails and said skid members are aligned to allow said tube bundle to slide along said skid members into and out of said shell.  
     
     
         13 . A boiler in accordance with  claim 11  wherein said inlet tube and said outlet tubes further comprise un-insulated metal tubes.  
     
     
         14 . A boiler in accordance with  claim 11  wherein said tube bundle further comprises a tube bundle dome on distal ends of said inlet tube and said return tubes, wherein said tube bundle dome is not a part of said shell.  
     
     
         15 . A boiler in accordance with  claim 14  wherein said tube bundle dome further comprises an inner concave surface adapted to turn hot combustion gases 180° back on itself from the direction of flow through said inlet tube for flow for said return tubes.  
     
     
         16 . A boiler in accordance with  claim 11  further comprising means for sealing said tube bundle; means for sealing said tube bundle inside said shell and means for sealing a distal end of said shell.  
     
     
         17 . A boiler comprising: 
 a. a shell;    b. a tube bundle exchanger seated inside said shell, said tube bundle comprising one inlet tube adapted to direct combustion gases in one direction and a plurality of return tubes in fluid communication with said inlet tube adapted to direct combustion gases in the opposite direction, and a tube bundle dome having a concave inner surface, said tube bundle dome fastened to said inlet tube and to said return tubes, whereby said concave inner surface turns the hot combustion gases 180° from their direction of flow through said inlet tube to flow toward in the opposite direction.    c. a plurality of parallel baffles spaced along the length of said inlet tube and said return tubes; and    d. means for inserting and removing said tube bundle from said shell.    
     
     
         18 . A boiler in accordance with  claim 17  where in said baffles further comprise a plurality of apertures with said inlet tube and said at least one return tube passing through one said aperture of each baffle, with each said tube free to float within said apertures.  
     
     
         19 . A boiler in accordance with  claim 17  further comprising means for inserting and removing said tube bundle from said shell.  
     
     
         20 . A boiler in accordance with  claim 17  further comprising means for sealing said tube bundle; means for sealing said tube bundle inside said shell and means for sealing a distal end of said shell.