Systems and methods for acid gas removal from a gaseous stream

Abstract

Apparatuses, systems, and methods for removing acid gases from a gas stream are provided. Gas streams include waste gas streams or natural gas streams. The methods include obtaining a hypochlorite and a carbonate or bicarbonate in an aqueous mixture, and mixing the aqueous mixture with the gas stream to produce sulfates or nitrates from sulfur-based and nitrogen-based acidic gases. Some embodiments of the present disclosure are directed to produce the carbonate and/or bicarbonate scrubbing reagent from CO 2 in the gas stream. Still others are disclosed.

1 . A system for effectively reducing pollutants from a gas stream comprising:
 a first set of mixing equipment adapted to admix a hydroxide with a gas stream to create a first admixture in which carbon dioxide in the gas stream can react with a hydroxide to produce a bicarbonate product or a combination of bicarbonate and carbonate products in a first liquid outflow and   a second set of mixing equipment adapted admix a hypochlorite and the bicarbonate product or the combination of bicarbonate and carbonate products with the gas stream to create a second admixture in which nitrogen-based or sulfur-based acid gases can react with the hypochlorite and the bicarbonate product or the combination of bicarbonate and carbonate products to produce nitrate or sulfate products in a second liquid outflow,   
       wherein a gas stream flows through the second set of mixing equipment before at least a portion of the gas stream flows through the first set of mixing equipment. 
     
     
         2 . The system of  claim 1 , further comprising a conduit adapted to transfer the liquid outflow to the second set of mixing equipment to create the second admixture. 
     
     
         3 . The system of  claim 1 , further comprising a chlor-alkali cell adapted to electrochemically produce the hydroxide with a protonated brine solution, wherein the chlor-alkali cell is in fluid communication with the first set of mixing equipment. 
     
     
         4 . The system of  claim 3 , further comprising a third set of mixing equipment adapted to admix hydroxide from the chlor-alkali cell with chlorine gas from the chlor-alkali cell, wherein the chlor-alkali cell is in fluid communication with the third set of mixing equipment and wherein the third set of mixing equipment is in fluid communication with the second set of mixing equipment. 
     
     
         5 . The system of  claim 3 , further comprising a fourth set of mixing equipment adapted to admix hydroxide from the chlor-alkali cell with the gas stream before at least a portion of the gas stream flows through the first set of mixing equipment. 
     
     
         6 . The system of  claim 3 , further comprising a burner adapted to combust hydrogen gas and chlorine gas from the chlor-alkali cell to produce hydrochloric acid. 
     
     
         7 . The system of  claim 4 , wherein at least a portion of the hydrochloric acid is in communication with the chlor-alkali cell to protonate a brine solution. 
     
     
         8 . The system of  claim 1 , wherein the gas stream is a natural gas stream or a flue-gas stream. 
     
     
         9 . The system of  claim 1 , wherein the acid gas is NO x , SO x , or H 2 S. 
     
     
         10 . The system of  claim 9 , further comprising a fifth set of mixing equipment adapted to convert the sulfate or nitrate products to ammonium sulfate or ammonium nitrate. 
     
     
         11 . The system of  claim 1 , wherein the acid gas is SO x  or H 2 S. 
     
     
         12 . The system of  claim 11 , further comprising a fifth set of mixing equipment adapted to separate the sulfate products from the second liquid outflow and form calcium sulfate in solid form. 
     
     
         13 . The system of  claim 1 , wherein the acid gas is NO x . 
     
     
         14 . The system of  claim 13 , further comprising a fifth set of mixing equipment adapted to convert the nitrate products to ammonium nitrate. 
     
     
         15 . The system of  claim 1 , wherein the second admixture comprises about 0.5% by weight to about 5% by weight of hypochlorite and about 0.5% by weight to about 5% by weight of bicarbonate. 
     
     
         16 . The system of  claim 15 , wherein the molar ratio of hypochlorite to bicarbonate is about 1:1 to about 5:1. 
     
     
         17 . The system of  claim 1 , wherein the first set of mixing equipment comprises two phases:
 a first phase adapted to admix the hydroxide with a portion of the gas stream exiting the second set of mixing equipment to produce carbonate products in a first phase liquid outflow and   a second phase adapted to admix the first phase liquid outflow with another portion of the gas stream exiting the second set of mixing equipment to produce bicarbonate products in the first liquid outflow.   
     
     
         18 . The system of  claim 1 , wherein the hypochlorite is in the form of sodium hypochlorite and the hydroxide is in the form of sodium hydroxide. 
     
     
         19 . A method of effectively reducing an amount of pollutants from a gas stream comprising
 (a) obtaining a hydroxide in an aqueous mixture;   (b) obtaining a hypochlorite in an aqueous mixture;   (c) admixing the hydroxide with carbon dioxide in the gas stream to produce bicarbonate products or a combination of carbonate and bicarbonate products in a first admixture, thereby sequestering the carbon dioxide in a mineral product form; and   (d) admixing the hypochlorite and at least a portion of the bicarbonate products or a combination of carbonate and bicarbonate products from the first admixture with a sulfur-based or nitrogen-based acid gas in the gas stream to produce nitrate or sulfate product in a second admixture, thereby sequestering the acid gas.   
     
     
         20 . The method of  claim 19 , wherein step (c) comprises altering the reaction equilibrium to favor the production of bicarbonate products. 
     
     
         21 . The method of  claim 19 , wherein obtaining the hydroxide comprises:
 obtaining a group-1 or group-2 salt;   admixing the salt with acid and water, acid and steam, or acid, water, and steam to produce a protonated salt solution; and electrolyzing the protonated salt solution to produce the hydroxide, a hydrogen gas, and a chlorine gas.   
     
     
         22 . The method of  claim 21 , wherein obtaining the hypochlorite comprises:
 admixing the hydroxide with the chlorine gas to produce the hypochlorite.   
     
     
         23 . The method of  claim 22 , further comprising obtaining the hydroxide in a second aqueous mixture and spraying the aqueous mixture to admix with the gas stream before the gas stream is admixed in step (c) and after the gas stream is admixed in step (d). 
     
     
         24 . The method of  claim 22 , further comprising obtaining the hydroxide in a second aqueous mixture and spraying the aqueous mixture to admix with the gas stream before the gas stream is admixed in step (c) and step (d). 
     
     
         25 . The method of  claim 21 , further comprising reacting the hydrogen gas and the chlorine gas to produce hydrochloric acid. 
     
     
         26 . The method of  claim 25 , wherein the protonated salt solution comprises at least a portion of the hydrochloric acid. 
     
     
         27 . The method of  claim 19 , wherein the gas stream is a natural gas stream or a flue-gas stream. 
     
     
         28 . The method of  claim 19 , wherein the acid gas is NO x , SO x , or H 2 S. 
     
     
         29 . The method of  claim 28 , further comprising reacting the sulfate or nitrate products with ammonia and carbon dioxide to produce a bicarbonate and ammonium sulfate or ammonium nitrate. 
     
     
         30 . The method of  claim 19 , wherein the acid gas is SO x  or H 2 S. 
     
     
         31 . The method of  claim 30 , further comprising separating the sulfate products from the second liquid outflow and converting the sulfate products to calcium sulfate. 
     
     
         32 . The method of  claim 19 , wherein the acid gas is NO x . 
     
     
         33 . The method of  claim 32 , further comprising a fifth set of mixing equipment adapted to convert the nitrate products to ammonium nitrate. 
     
     
         34 . The method of  claim 19 , wherein admixing the hypochlorite and at least a portion of the bicarbonate products or a combination of carbonate and bicarbonate products comprises admixing a solution or the combination of solutions comprising 0.5% by weight to about 5% by weight of hypochlorite and about 0.5% by weight to about 5% by weight of bicarbonate. 
     
     
         35 . The method of  claim 34 , wherein the molar ratio of hypochlorite to bicarbonate is about 1:1 to about 5:1. 
     
     
         36 . The method of  claim 19 , wherein the hypochlorite is in the form of sodium hypochlorite and the hydroxide is in the form of sodium hydroxide. 
     
     
         37 . A method to scrubbing natural gas stream, wherein the scrubbing phase consists essentially of
 admixing hypochlorite and bicarbonate with a sulfur-based or nitrogen-based acid gas in the natural gas stream to produce nitrate or sulfate product in an admixture, thereby sequestering the acid gas.   
     
     
         38 . The method of  claim 37 , wherein the concentration of hypochlorite is 0.5% by weight to 5% by weight and the concentration of bicarbonate is 0.5% by weight to 5% by weight. 
     
     
         39 . The method of  claim 38 , wherein the molar ratio of hypochlorite to bicarbonate is about 1:1 to about 5:1.