Fluidized bed granulation

Abstract

Method and fluidized bed reactor for the production of granules, such as granules of urea or ammonium nitrate. The fluidized bed reactor comprises at least one granulation compartment with air inlets, and an air moving device downstream of the granulation compartment, e.g., downstream of at least one scrubbers. The air moving device is configured to draw air through said at least one air inlet into at least one granulation compartment.

1 . A fluidized bed reactor comprising at least one granulation compartment with one or more air inlets, and at least one air moving device downstream the granulation compartment configured to draw air through said one or more air inlets into the granulation compartment. 
     
     
         2 . The fluidized bed reactor according to  claim 1 , comprising a scrubber downstream the granulation compartment, wherein the at least one air moving device is downstream the scrubber. 
     
     
         3 . The fluidized bed reactor according to  claim 1  comprising at least one after-cooler and the at least one an air moving device downstream the after-cooler. 
     
     
         4 . The fluidized bed reactor according to  claim 3 , comprising a scrubber downstream the after-cooler, the at least one air moving device being positioned downstream the scrubber. 
     
     
         5 . The fluidized bed reactor according to  claim 1 , wherein the air moving device comprises one or more exhaust fans for discharging air. 
     
     
         6 . A method for producing granules using a fluidized bed reactor comprising at least one granulation compartment having one or more air inlets and a bed of granules, and at least one air moving device downstream the granulation compartment, the method comprising: drawing air in the at least one granulation compartment through the one or more air inlets using the at least one air moving device; and fluidizing the bed of granules with the drawn in air. 
     
     
         7 . The method of  claim 6 , wherein drawing air in the at least one granulation compartment includes creating a pressure drop between the one or more air inlets and an air exhaust below 800 mm water column. 
     
     
         8 . The method of  claim 7 , wherein the pressure drop is below 750 mm water column. 
     
     
         9 . The method according to  claim 6 , wherein the pressure drop over the granulation compartment is at most 500 mm water column. 
     
     
         10 . The method according to  claim 6 , wherein the bed of granules include urea granules. 
     
     
         11 . The method according to  claim 6 , wherein the bed of granules include ammonium nitrate granules. 
     
     
         12 . A fluidized bed reactor comprising at least one granulation compartment with at least one air inlets and at least one air moving device, configured to move air through said at least one air inlet into said at least one granulation compartment, characterized in that said air is moved essentially by the action of said at least one air moving device downstream of said granulation compartment. 
     
     
         13 . The fluidized bed reactor according to  claim 12 , devoid of any air moving device which is configured to move air through said at least one air inlet into said granulation compartment and which is positioned upstream of the granulation compartment. 
     
     
         14 . The fluidized bed reactor according to  claim 12 , comprising at least one after-cooler wherein the at least one air moving device is positioned downstream of the at least one after-cooler. 
     
     
         15 . The fluidized bed reactor according to  claim 14 , wherein the at least one after-cooler is integrated in the fluidized bed reactor as a set of at least two compartments subsequent to the granulation compartments. 
     
     
         16 . The fluidized bed reactor according to  claim 12 , comprising at least one scrubber downstream of the at least one granulation compartment, wherein the at least one air moving device is positioned downstream of the at least one scrubber. 
     
     
         17 . The fluidized bed reactor according to  claim 14 , further comprising at least one scrubber downstream of the at least one after-cooler, wherein the at least one air moving device is positioned downstream of the at least one scrubber. 
     
     
         18 . The fluidized bed reactor according to  claim 12 , wherein the at least one air moving device comprises at least one exhaust fan for discharging air. 
     
     
         19 . A method for the production of granules using a fluidized bed reactor comprising at least one granulation compartment with at least one air inlets and at least one air moving device, configured to move air through said at least one air inlet into said at least one granulation compartment, wherein said air is moved essentially by the action of said at least one air moving device downstream of said granulation compartment, the method comprising: drawing air in the at least one granulation compartment through the at least one air inlet using the at least one air moving device; and fluidizing the bed of granules with said drawn in air. 
     
     
         20 . The method according to  claim 19 , devoid of any air moving step by an air moving device which is configured to move air through said at least one air inlet into said granulation compartment and which is positioned upstream of the granulation compartment. 
     
     
         21 . The method according to  claim 19 , wherein drawing air in the at least one granulation compartment includes creating a pressure drop between the at least one air inlet and an air exhaust of between 10 and 100 mbar. 
     
     
         22 . The method according to  claim 21 , wherein the pressure drop is between 10 and 80 mbar. 
     
     
         23 . The method according to  claim 19 , wherein drawing air in the at least one granulation compartment includes creating a pressure drop over the granulation compartment of between 10 and 60 mbar. 
     
     
         24 . The method according to  claim 19 , wherein the air drawn into the at least one granulation compartment is not preheated, either deliberately using pre-heating equipment, or as a side effect of the action of upstream equipment. 
     
     
         25 . The method according to  claim 19 , wherein the bed of granules include urea-based granules. 
     
     
         26 . The method according to  claim 19 , wherein the bed of granules include ammonium nitrate-based granules. 
     
     
         27 . The method according to  claim 25 , wherein the urea based granules are urea, urea ammonium nitrate, urea ammonium sulphate or urea doped with elemental sulphur. 
     
     
         28 . The method according to  claim 26 , wherein the ammonium nitrate-based granules are ammonium nitrate granules or calcium nitrate granules. 
     
     
         29 . A fluidized bed reactor comprising
 at least one granulation compartment with one or more air inlets;   at least one scrubber downstream from the at least one granulation compartment;   at least one air duct between the at least one granulation compartment and the at least one scrubber;   and at least one air moving device downstream from the at least one granulation compartment,   wherein when a fluid bed is present in the at least one granulation compartment, the at least one air moving device has or devices have sufficient capacity to create a vacuum exceeding the total pressure drop between the one or more air inlets and the at least one air moving device.   
     
     
         30 . The fluidized bed reactor according to  claim 29 , wherein the at least one air moving device is downstream from the scrubber. 
     
     
         31 . The fluidized bed reactor according to  claim 29 , further comprising at least one after-cooler downstream from the at least one granulation compartment. 
     
     
         32 . The fluidized bed reactor according to  claim 31 , wherein the after-cooler is upstream from a scrubber and the at least one air moving device is positioned downstream from the scrubber. 
     
     
         33 . The fluidized bed reactor according to  claim 31 , wherein the air moving device comprises one or more exhaust fans for discharging air. 
     
     
         34 . A method for producing granules using a fluidized bed reactor comprising
 at least one granulation compartment having one or more air inlets and a bed of granules,   at least one scrubber downstream from the at least one granulation compartment,   at least one air duct between the at least one granulation compartment and the at least one scrubber, and   at least one air moving device downstream from the at least one granulation compartment,   the method comprising fluidizing the bed of granules by drawing air into the at least one granulation compartment through the one or more air inlets using the at least one air moving device,   wherein the air drawn into the at least one granulation compartment is not heated by a blower upstream from the one or more air inlets.   
     
     
         35 . The method of  claim 34 , wherein drawing air in the at least one granulation compartment includes creating a pressure drop between the one or more air inlets and an air exhaust below 800 mm water column. 
     
     
         36 . The method of  claim 35 , wherein the pressure drop is below 750 mm water column. 
     
     
         37 . The method according to  claim 34 , wherein the pressure drop over the granulation compartment is at most 500 mm water column. 
     
     
         38 . The method according to  claim 34 , wherein the bed of granules include urea granules. 
     
     
         39 . The method according to  claim 34 , wherein the bed of granules include ammonium nitrate granules. 
     
     
         40 . A method for producing fertilizer granules by crystallization of urea and/or ammonium nitrate, using a fluidized bed reactor comprising
 at least one granulation compartment with one or more air inlets and a bed of granules,   at least one scrubber downstream from the at least one granulation compartment,   at least one air duct between the at least one granulation compartment and the at least one scrubber, and   at least one air moving device downstream from the at least one granulation compartment,   the method comprising fluidizing the bed of granules by drawing air into the at least one granulation compartment through the one or more air inlets using the at least one air moving device,   wherein the air drawn into the at least one granulation compartment is not heated by a blower upstream from the one or more air inlets.