Silo for storing bulk products, in particular dried sludge from water treatment plants

Abstract

The invention relates to a silo for storing dried bulk products containing organic materials, in particular for storing dried sludge from residual water treatment plants, said products being subject to self-heating phenomena, wherein said silo includes an outer shell ( 1 ) having an upper portion and a lower portion, the shell being made of an essentially metallic heat-conducting material and comprising at least an inlet and an outlet for the products, a roof ( 2 ) closing the silo in the upper portion, and a discharge device ( 3 ) closing the silo in the lower portion. The silo includes at least one inner stack ( 5 ) of an essentially metallic heat-conducting material that communicates with the atmosphere in the upper and lower portions, the volume inside the stack being void so as to permit air circulation and heat dispersal, and the ratio d/D between the outer diameter d of the stack ( 5 ) and the outer diameter D of the shell being higher than 0.12.

1 . A silo for the storage of bulk products containing organic matter, in particular for the storage of dried sludge from wastewater treatment plants, in which products self-heating occurs, the silo comprising a cylindrical or prismatic outer shell of vertical axis, having a top and a bottom, this shell being made of a thermally conductive material, especially a metallic material, and comprising at least one inlet and one outlet for the products, a roof closing the silo at the top and a discharge device closing the silo at the bottom, the silo having at least one hollow internal shaft ( 5 ,  5 ′) made of a thermally conductive material, in particular a metallic material, which communicates with the atmosphere at the top and at the bottom, the internal volume of the shaft being free to allow air circulation and heat dissipation,
 wherein the ratio d/D of the outside diameter d of the shaft ( 5 ,  5 ′) to the outside diameter D of the shell is greater than 0.12.   
     
     
         2 . A silo for the storage of bulk products containing organic matter, in particular for the storage of dried sludge from wastewater treatment plants, in which products self-heating occurs, the silo comprising a cylindrical or prismatic outer shell of vertical axis, having a top and a bottom, this shell being made of a thermally conductive material, especially a metallic material, and comprising at least one inlet and one outlet for the products, a roof closing the silo at the top and a discharge device closing the silo at the bottom, the silo having at least one coaxial hollow internal shaft ( 5 ,  5 ′) made of a thermally conductive material, in particular a metallic material, which communicates with the atmosphere at the top and at the bottom, the internal volume of the shaft being free to allow air circulation and heat dissipation,
 wherein the outside diameter d of the shaft is greater than (D−4R c ), D being the outside diameter of the shell and R c  being the critical radius of the products to be stored in the silo.   
     
     
         3 . A silo for the storage of bulk products containing organic matter, in particular for the storage of dried sludge from wastewater treatment plants, in which products self-heating occurs, the silo comprising a cylindrical or prismatic outer shell of vertical axis, having a top and a bottom, this shell being made of a thermally conductive material, especially a metallic material, and comprising at least one inlet and one outlet for the products, a roof closing the silo at the top and a discharge device closing the silo at the bottom, the silo having at least one hollow internal shaft ( 5 ,  5 ′) made of a thermally conductive material, in particular a metallic material, which communicates with the atmosphere at the top and at the bottom, the internal volume of the shaft being free to allow air circulation and heat dissipation,
 wherein the shaft ( 5 ′) is in an eccentric position relative to the shell ( 1 ), the eccentricity of the shaft ( 5 ′) being equal to one half of its outside diameter (i.e. d/2), the critical radius R c  being equal to or greater than D/4 (i.e. R c ≧D/4).   
     
     
         4 . The silo as claimed in  claim 1 , wherein the shell ( 1 ) includes, on the inside at the bottom, a support means (B) for supporting the internal shaft ( 5 ,  5 ′) and suitable for this internal shaft to communicate with the atmosphere, while preventing any ingress of product into said internal shaft. 
     
     
         5 . The silo as claimed in  claim 4 , wherein the means (B) for supporting the internal shaft ( 5 ,  5 ′) is designed to allow rainwater to drain away and air to circulate. 
     
     
         6 . The silo as claimed in  claim 4 , wherein the support means (B) comprises tubes ( 6 ) welded to the shaft ( 5 ,  5 ′) and running into this shaft, each tube ( 6 ) passing through that wall of the shell to which it is welded and running to the outside. 
     
     
         7 . The silo as claimed in  claim 6 , wherein the support means (B) comprises three tubes ( 6 ) forming a tripod. 
     
     
         8 . The silo as claimed in  claim 1 , wherein the diameter of the shell ( 1 ) is at least three meters, the internal shaft ( 5 ,  5 ′) having a diameter of at least one meter.