Treatment of spent caustic refinery effluents

Abstract

In the methods for treatment of caustic effluents described in the specification, a spent caustic refinery effluent is supplied to a submerged combustion gas evaporator in which hot combustion gas containing carbon dioxide is injected into the caustic liquid to concentrate the liquid and convert a hydroxide constituent to a carbonate. Where the caustic effluent is from a petroleum refinery, oil in the waste liquid is separated from the aqueous constituent before, during or after concentration.

1 - 19 . (canceled)  
   
   
       20 . A device for treating caustic effluents comprising: 
 a submerged combustion gas evaporator comprising: 
 a vessel having an interior adapted to hold a liquid;  
 a tube disposed within the vessel and adapted to transport a combustion gas into the interior of the vessel;  
 a caustic effluent inlet adapted to supply the caustic effluent to the interior of the vessel;  
 at least one mixing pipe that transports combustion gas from a burner to the interior of the vessel and releases the combustion gas at a level below a surface of the caustic effluent; and  
 an exhaust line adapted to transport exhaust gases from the interior of the vessel,  
 wherein the combustion gas is formed from combusting a biogas.  
   
   
   
       21 . The device of  claim 20  further comprising: an outlet in the vessel for removing concentrated liquid and precipitates.  
   
   
       22 . The device of  claim 21  further comprising: an oil separator connected to the outlet for removing oil from the concentrated liquid.  
   
   
       23 . The device of  claim 20  further comprising: a demister connected to the exhaust line for removing entrained liquid droplets from the exhaust gases.  
   
   
       24 . The device of  claim 23  further comprising: an exhaust gas purifier connected to the exhaust line downstream of the demister for removing volatile compounds from the exhaust gases via thermal oxidation.  
   
   
       25 . The device of  claim 20  further comprising: a heat exchanger connected to the caustic effluent inlet and the exhaust line for preheating the caustic effluent prior to treatment in the vessel.  
   
   
       26 . The device of  claim 20  further comprising: a heat exchanger connected to the tube for preheating the combustion gas.  
   
   
       27 . The device of  claim 20  wherein the caustic effluent is produced in a petroleum refinery.  
   
   
       28 . The device of  claim 20  wherein the caustic effluent is produced in an aluminum manufacturing facility.  
   
   
       29 . A device for treating caustic effluents comprising: 
 a submerged combustion gas evaporator comprising: 
 a vessel having an interior adapted to hold a liquid;  
 a tube disposed within the vessel and adapted to transport a combustion gas into the interior of the vessel;  
 a caustic effluent inlet adapted to supply the caustic effluent to the interior of the vessel;  
 at least one mixing pipe that transports combustion gas from a burner to the interior of the vessel and releases the combustion gas at a level below a surface of the caustic effluent; and  
 an exhaust line adapted to transport exhaust gases from the interior of the vessel,  
 wherein the caustic effluent is an industrial waste liquid.  
   
   
   
       30 . The device of  claim 29  further comprising: a blower for supplying the combustion gas under positive pressure to the vessel.  
   
   
       31 . The device of  claim 29  further comprising: an induction fan for supplying the combustion gas under negative pressure to the vessel.  
   
   
       32 . The device of  claim 29  further comprising: an outlet from removing concentrated liquid and precipitates.  
   
   
       33 . A method of treating spent caustic refinery effluents and sequestering carbon dioxide from a combustion gas, the method comprising: 
 supplying a spent caustic refinery effluent to a submerged combustion gas evaporator;    supplying combustion gas containing carbon dioxide to the submerged combustion gas evaporator at a temperature and quantity high enough to vaporize water and volatile constituents in the spent caustic refinery effluent and concentrate a constituent of the spent caustic refinery effluent; and    reacting the carbon dioxide in the combustion gas with an alkaline component of the spent caustic refinery effluent thereby sequestering carbon dioxide from the combustion gas and converting a portion of the alkaline component into a product of the reaction between the carbon dioxide and the alkaline component, the product being removable from the submerged combustion gas evaporator as one of a precipitate and a dissolved substance.    
   
   
       34 . The method of  claim 33  further comprising: removing the product through an outlet in the submerged combustion gas evaporator.  
   
   
       35 . The method of  claim 34  further comprising: separating oil from the product in an oil separator.  
   
   
       36 . The method of  claim 33  further comprising: removing exhaust gases from the submerged combustion gas evaporator.  
   
   
       37 . The method of  claim 36  further comprising: removing entrained liquid droplets from the exhaust gases with a demister.  
   
   
       38 . The method of  claim 36  further comprising: removing volatile compounds in the exhaust gases with an exhaust gas purifier.  
   
   
       39 . The method of  claim 38  wherein the volatile compounds are removed via thermal oxidation.