Boiler Water Cycle of a Fluidized Bed Reactor and a Fluidized Bed Reactor

Abstract

A boiler water cycle of a fluidized bed boiler, preferably, a supercritical once-through-unit (OTU) boiler, includes a drop leg, a number of horizontal inlet headers, substantially having a length of the length of a front wall of the furnace of the boiler, arranged below the furnace, and panels of water tubes of the front wall and a rear wall, extensions of the water tubes being directly connected to the inlet headers, wherein each inlet header is in flow communication with a drop leg by way of an inlet duct connected to the end of the inlet header. The inlet headers include a front wall chamber below the front wall of the furnace, a rear wall chamber arranged below the rear wall of the furnace, and at least one grid chamber below the center part of the furnace grid in a wind box of the fluidized bed boiler.

1 . A boiler water cycle of a fluidized bed boiler, the boiler water cycle comprising
 a drop leg;   a number of horizontal inlet headers, substantially having a length of the length of a front wall of a furnace of the boiler, arranged below the furnace, and panels of water tubes of the front wall and a rear wall, extensions of the water tubes being directly connected to the inlet headers, wherein each inlet header is in flow communication with a drop leg by an inlet duct connected to the end of the inlet header,   wherein the inlet headers comprise a front wall chamber below the front wall of the furnace, a rear wall chamber arranged below the rear wall of the furnace, and at least one grid chamber below the center part of the furnace grid in a wind box of the fluidized bed boiler.   
   
   
       2 . A boiler water cycle according to  claim 1 , wherein the boiler water cycle is a supercritical once-through cycle. 
   
   
       3 . A boiler water cycle according to  claim 1 , wherein each inlet header is in flow communication with only one drop leg. 
   
   
       4 . A boiler water cycle according to  claim 3 , wherein each inlet header is in flow communication with a common drop leg. 
   
   
       5 . A boiler water cycle according to  claim 1 , wherein a portion of the extensions of water tubes in the front wall are connected directly to the front wall chamber, a portion of the extensions of water tubes in the rear wall are connected directly to the rear wall chamber and another portion of the water tubes in the front wall and another portion of the water tubes in the rear wall extend parallel to the furnace grid as grid tubes connected to the grid chamber. 
   
   
       6 . A boiler water cycle according to  claim 1 , wherein the diameter of the water tubes in the front wall and rear wall is smaller than the diameter of the grid tubes, and each water tube of the other portion of the water tubes of the front wall and rear wall is connected to the grid tube by a fitting member. 
   
   
       7 . A boiler water cycle according to  claim 5 , wherein the inlet headers comprise two grid chambers and the other portion of the extensions of the water tubes in the front wall is connected to the first grid chamber and the other portion of the extensions of the water tubes in the rear wall is connected to the second grid chamber. 
   
   
       8 . A boiler water cycle according to  claim 1 , wherein the inner diameter of the inlet headers is at least 200 mm. 
   
   
       9 . A boiler water cycle according to  claim 7 , wherein the inner diameter of the inlet headers is at least 300 mm. 
   
   
       10 . A boiler water cycle according to  claim 7 , wherein the grid chamber is arranged to act as a supporting element of the grid. 
   
   
       11 . A fluidized bed boiler comprising:
 a boiler water cycle, the boiler water cycle comprising:   (i) a drop leg; and   (ii) a number of horizontal inlet headers, substantially of the length of a front wall of a furnace of the boiler, arranged below the furnace, and panels of water tubes of the front wall and a rear wall, extensions of the water tubes being directly connected to the inlet headers, wherein each inlet header is in flow communication with a drop leg merely by an inlet duct connected to the end of the inlet header,   wherein the inlet headers comprise a front wall chamber below the front wall of the furnace, a rear wall chamber arranged below the rear wall of the furnace, and at least one grid chamber below the center part of the furnace grid in a wind box of the fluidized bed boiler.   
   
   
       12 . A bed boiler water cycle according to  claim 2 , wherein each inlet header is in flow communication with only one drop leg. 
   
   
       13 . A fluidized bed boiler according to  claim 11 , wherein the boiler water cycle is a supercritical once-through cycle. 
   
   
       14 . A fluidized bed boiler according to  claim 11 , wherein each inlet header is in flow communication with only one drop leg. 
   
   
       15 . A fluidized bed boiler according to  claim 14 , wherein each inlet header is in flow communication with a common drop leg. 
   
   
       16 . A fluidized bed boiler according to  claim 11 , wherein a portion of the extensions of water tubes in the front wall are connected directly to the front wall chamber, a portion of the extensions of water tubes in the rear wall are connected directly to the rear wall chamber and another portion of the water tubes in the front wall and another portion of the water tubes in the rear wall extend parallel to the furnace grid as grid tubes connected to the grid chamber. 
   
   
       17 . A fluidized bed boiler according to  claim 11 , wherein the diameter of the water tubes in the front wall and rear wall is smaller than the diameter of the grid tubes, and each water tube of the other portion of the water tubes of the front wall and rear wall is connected to the grid tube by a fitting member. 
   
   
       18 . A fluidized bed boiler according to  claim 16 , wherein the inlet headers comprise two grid chambers and the other portion of the extensions of the water tubes in the front wall is connected to the first grid chamber and the other portion of the extensions of the water tubes in the rear wall is connected to the second grid chamber. 
   
   
       19 . A fluidized bed boiler according to  claim 11 , wherein the inner diameter of the inlet headers is at least 200 mm. 
   
   
       20 . A fluidized bed boiler according to  claim 18 , wherein the inner diameter of the inlet headers is at least 300 mm. 
   
   
       21 . A fluidized bed boiler according to  claim 18 , wherein the grid chamber is arranged to act as a supporting element of the grid. 
   
   
       22 . A fluidized bed boiler according to  claim 12 , wherein each inlet header is in flow communication with only one drop leg.