Exhaust gas treatment system

Abstract

A method and system for treating exhaust gas from stationary engines used to generate electricity is provided. Substantially all of the exhaust gases from at least one stationary combustion engine used for electrical power generation are collected and routed to an absorption tower. Inside the absorption tower the exhaust gases travel upwards in and through a plurality of perforated plates to a gas outlet in a top of the absorption tower. While the gas is ascending in the absorption tower, water is sprayed on the ascending gas and the perforated plates and this water is collected in the bottom of the absorption tower where at least some of it will be reused by spraying it back into the absorption tower to treat more exhaust gas from the combustion engines.

1 . A method for treating exhaust gas from stationary engines used to generate electricity, the method comprising:
 capturing substantially all of the exhaust gases from at least one stationary combustion engine used for electrical power generation and routing substantially all of the exhaust gases to an absorption tower;   allowing the exhaust gases to travel upwards in an interior of the absorption tower through a plurality of perforated plates to a gas outlet in a top end of the absorption tower;   spraying water on the plurality of perforated plates and the exhaust gas as it travels upwards in the absorption tower;   collecting water that was sprayed in the absorption tower in a bottom end of the absorption tower, the water containing nitrous oxides, sulfur dioxides and particulates removed from the exhaust gas; and   reusing at least a portion of the water collected in the bottom end of the absorption tower to spray the at least a portion of the water back into the interior of the absorption tower.   
     
     
         2 . The method of  claim 1  wherein the temperature of exhaust gas entering the absorption tower is from 90° C. to 115° C. 
     
     
         3 . The method of  claim 1  further comprising cooling the exhaust gas rising through the interior of the absorption tower to a temperature from 70° C. to 90° C. 
     
     
         4 . The method of  claim 1  further comprising cooling the exhaust gas to a temperature from 105° C. to 125° C. before routing the exhaust gas into the interior of the absorption tower. 
     
     
         5 . The method of  claim 1  further comprising routing water collected in the bottom end of the absorption tower to a settling tank and allowing particles suspended in the water to settle out before reusing the at least a portion of the water to spray back into the interior of the absorption tower. 
     
     
         6 . The method of  claim 1  further comprising cooling the at least a portion of the water to a temperature from 25° C. to 35° C. before spraying the at least a portion of the water back into the interior of the absorption tower. 
     
     
         7 . The method of  claim 1  further comprising increasing the pH of the at least a portion of the water to a pH from 6.5 to 7.0 before spraying the at least a portion of the water back into the absorption tower. 
     
     
         8 . The method of  claim 1  wherein the gas exiting the absorption tower is exhausted to the atmosphere. 
     
     
         9 . The method of  claim 1  wherein the gas exiting the absorption tower is collected and routed for carbon dioxide extraction. 
     
     
         10 . A system for treating exhaust gas produced by combustion engines during the generation of electricity, the system comprising:
 at least one stationary combustion engine adapted to generate electricity;   an absorption tower having:
 an interior space; 
 an exhaust inlet provided near a bottom end of the absorption tower; 
 a gas outlet provided in a top end of the absorption tower; 
 a plurality of plates provided in the interior of the absorption tower between the exhaust inlet and the gas outlet, each plate having a plurality of perforations; 
 a series of vertically spaced spray nozzles, each spray nozzle directed into the interior of the absorption tower; and 
 a water outlet provided proximate a bottom end of the absorption tower and below the exhaust inlet, 
   at least one exhaust conduit connecting the at least one stationary combustion engine to the absorption tower and operative to route substantially all of the exhaust gases from the at least one stationary combustion engine to the exhaust inlet of the absorption tower; and   a sprayer system operatively connected to the water outlet of the absorption tower to route water from the absorption tower to the series of vertically spaced spray nozzles.   
     
     
         11 . The system of  claim 10  wherein the at least one stationary combustion engine is natural gas fired. 
     
     
         12 . The system of  claim 10  wherein the plurality of plates are angled downwards towards the bottom end of the absorption tower. 
     
     
         13 . The system of  claim 12  wherein the series of vertically spaced spray nozzles are directed at the plurality of plates. 
     
     
         14 . The system of  claim 10  wherein the plurality of plates forms a circuitous path that exhaust gas rising through the absorption tower from the exhaust inlet must pass through before exiting through the gas outlet 
     
     
         15 . The system of  claim 10  further comprising a caustic injection system to increase the pH of water being routed to the series of vertically spaced spray nozzles. 
     
     
         16 . The system of  claim 10  further comprising a settling tank connected to the water outlet so that water that has collected in the bottom end of the absorption tower is routed to the settling tank before being routed to the series of vertically spaced spray nozzles. 
     
     
         17 . The system of  claim 16  further comprising at least one cooling tank to positioned after the settling tank in the system to cool the water to a temperature between 25° C. and 35° C. before routing the water to the series of vertically spaced spray nozzles. 
     
     
         18 . The system of  claim 17  wherein the at least one cooling tank is a spray-type cooling tank. 
     
     
         19 . The system of  claim 10  further comprising a heat exchanger provided inline of the at least one exhaust conduit to cool exhaust gas passing through the exhaust conduit. 
     
     
         20 . The system of  claim 10  wherein the sprayer system includes a pump for pressurizing water being routed to the series of vertically spaced spray nozzles