Emission control system

A method of treating a combustion flue gas stream for removal of at least oxides of sulfur and oxides of nitrogen, the method comprising:

• cooling the combustion flue gas stream, thereby generating a cooled gas stream;
• washing the cooled gas stream with a water wash, thereby generating a washed gas stream;
• scrubbing the washed gas stream, thereby generating a first scrubbed gas stream and a first scrubber liquor;
• removing solids from the first scrubber liquor, thereby generating a first recycled scrubber liquor;
• combining a portion of the first recycled scrubber liquor with a first hydrogen peroxide solution as a first scrubbing mixture for use in scrubbing the washed gas stream and controlling a flow rate of the first hydrogen peroxide solution to maintain a predetermined level of hydrogen peroxide in the first scrubbing mixture;
• removing a remaining portion of the first recycled scrubber liquor, thereby isolating a by-product stream containing sulfuric acid;
• demisting the first scrubbed gas stream, thereby generating a demisted gas stream;
• oxidizing the demisted gas stream using a second hydrogen peroxide solution, thereby generating an oxidized gas stream, wherein the second hydrogen peroxide solution is generated using a process comprising:
• feeding an aqueous hydrogen peroxide solution to a first inlet of a concentrator having a membrane to separate the aqueous hydrogen peroxide solution from a sweep gas, the aqueous hydrogen peroxide solution having an initial concentration of less than 70% by volume;
• feeding the sweep gas to a second inlet of the concentrator, wherein a pressure of the sweep gas is less than a pressure of the aqueous hydrogen peroxide solution and a pressure differential across the membrane is approximately 100 psi or less;
• transporting water from the aqueous hydrogen peroxide solution through the membrane to be taken up by the sweep gas, thereby generating a wet sweep gas;
• removing a concentrated hydrogen peroxide solution from a first outlet of the concentrator as the second hydrogen peroxide solution;
• and
• removing the wet sweep gas from a second outlet of the concentrator;
• scrubbing the oxidized gas stream, thereby generating a second scrubbed gas stream and a second scrubber liquor;
• removing solids from a portion of the second scrubber liquor, thereby generating a second recycled scrubber liquor;
• combining the second recycled scrubber liquor with a third hydrogen peroxide solution as a second scrubbing mixture for use in scrubbing the oxidized gas stream and controlling a flow rate of the third hydrogen peroxide solution to maintain a predetermined level of hydrogen peroxide in the second scrubbing mixture;
• removing a remaining portion of the second scrubber liquor, thereby isolating a by-product stream containing nitric acid;
• and
• neutralizing the second scrubbed gas by contacting it with a base, thereby generating a neutralized gas stream.

A system for the removal of at least oxides of sulfur and oxides of nitrogen from a combustion flue gas, the system comprising:

• a heat exchanger coupled to receive the flue gas;
• a water wash coupled to receive an exit gas stream from the heat exchanger;
• a first scrubber coupled to receive an exit gas stream from the water wash and coupled to receive a first hydrogen peroxide solution and a recycled liquor from the first scrubber;
• a demister coupled to receive an exit gas stream from the first scrubber;
• an oxidation tower coupled to receive an exit gas stream from the demister and a second hydrogen peroxide solution from a hydrogen peroxide concentrator;
• a second scrubber coupled to receive an exit gas stream from the oxidation tower and coupled to receive a third hydrogen peroxide solution and a recycled liquor from the second scrubber;
• and
• a neutralizer coupled to receive an exit gas stream from the second scrubber;
• wherein the hydrogen peroxide concentrator comprises a membrane for separating the second hydrogen peroxide solution from a sweep gas;
• and
• wherein the membrane is selective to the permeability of water over the permeability of hydrogen peroxide, thereby allowing water to transport through the membrane from the second hydrogen peroxide solution to the sweep gas.