Tank for energy recovery

Abstract

A tank for waste water partially or fully buried in the ground or immersed in water includes a wall made of a high thermal conductivity material, which in turn has a pair of walls forming a cavity creating a circuit of a convective fluid for heat exchange with both the waste water contained inside the tank and with the ground and/or groundwater external to the tank.

The invention claimed is: 
     
         1 . A tank ( 1 ) for waste water (A) coming from civil, industrial, commercial, and agricultural units, adapted to be partially or fully buried, being in contact with a ground and/or groundwater or an underground body of water, comprising:
 a wall ( 11 );   a bottom ( 12 ); and   a lid ( 13 ) for closure,   wherein at least said wall ( 11 ) is made of a thermally conductive material, and   wherein said wall ( 11 ) comprises a pair of walls ( 21 ,  22 ) forming a cavity ( 23 ), in which a circuit (Wb) is created for a convective exchange fluid (B) for heat exchange with both the waste water (A) contained inside ( 14 ) the tank ( 1 ) and with the ground and/ or water outside (E) the tank ( 1 ).   
     
     
         2 . The tank ( 1 ), according to  claim 1 , wherein said circuit (Wb) for said exchange fluid (B) is connected to a heating/cooling pump (C). 
     
     
         3 . The tank ( 1 ), according to  claim 1 , wherein said bottom ( 12 ) is made of a thermally conductive material and includes a double wall creating a cavity ( 24 ) communicating with said cavity ( 23 ) in the wall ( 11 ). 
     
     
         4 . The tank ( 1 ), according to  claim 1 ,
 further comprising at least one baffle and one or more dividers ( 15 ,  16 ,  17 ) mounted on an inside ( 14 ) of the tank ( 1 ) for separation of waste products and creating a circuit (Wa) for waste water (A) circulation between an inlet (S 1 ) and an outlet (S 1 , S 2 ), respectively connected to an incoming waste water pipe (S) and to an outlet pipe (F 1 ) that leads to a public sewer network (F),   wherein said baffle is T-shaped ( 15 ,  16 ) and is formed by a first baffle ( 15 )M, which divides an interior ( 14 ) into two parts ( 141 ,  142 ) communicating with each other, and a second baffle ( 16 ) transverse to said first baffle ( 15 ), said T-shaped baffle ( 15 ,  16 ) being spaced from the bottom ( 12 ) of the tank ( 1 ) so as to create a passage (Al) for flow (Wa) of waste water (A) between said inlet (S 1 ) and outlet (S 2 ), which are placed near a top of the tank ( 1 ), and   wherein, on the bottom ( 12 ) of said tank ( 1 ), there is at least one divider ( 17 ).   
     
     
         5 . The tank ( 1 ), according to  claim 4 , wherein said at least one baffle ( 15 ,  16 ) comprises a double wall, which creates one or more cavities ( 25 ) communicating with said cavities ( 23 ,  24 ) of the wall ( 11 ) and the bottom ( 12 ) of the tank, such that said exchange fluid (B) also circulates in said cavity ( 25 ) of said baffles ( 15 ,  16 ), increasing an exchange surface with the waste water (A) inside ( 14 ) the tank ( 1 ). 
     
     
         6 . The tank ( 1 ), according to  claim 1 , wherein at least one helical baffle ( 19 ) is mounted inside said cavity ( 23 ) of said wall ( 11 ) of the tank ( 1 ), the at least one helical baffle creating a substantially spiral forced path (Wb) inside said cavity ( 23 ) of said wall ( 11 ). 
     
     
         7 . The tank ( 1 ), according to  claim 6 , further comprising a plurality of fins ( 18 ) which are configured to increase an exchange surface between the convective fluid (B) and the outside (E) of the tank ( 1 ), the plurality of fins being mounted at least outside said wall ( 11 ) of the tank ( 1 ). 
     
     
         8 . The tank ( 1 ), according to  claim 6 , wherein said heat exchange fluid is a glycol based fluid (B) and that said wall ( 11 ), said bottom ( 12 ), and said baffles ( 15 ,  16 ) are made of stainless steel. 
     
     
         9 . The tank ( 1 ), according to  claim 2 , wherein said circuit (Wb) of the exchange fluid (B) is connected to said heating/cooling pump (C) in two circuits, of which one is for hot season and one for cold season, and wherein said tank (V) comprises at least one pair of exchange fluid (B) delivery/return connections (B 1 , B 2 ) for operation in the hot season and at least one pair of exchange fluid (B) delivery/return connections (B 3 , B 4 ) for operation in the cold season. 
     
     
         10 . The tank ( 1 ), according to  claim 1 , wherein the tank is cylindrical or prismatic, with a diameter between 80 and 100 cm and a height between 160 and 200 cm.