SNOX™ technology

Conventional flue gas desulfurization (FGD) methods are plagued by high operating costs, massive limestone consumption, and production of contaminated gypsum that must be deposited. This makes conventional FGD’s increasingly expensive to operate, particularly as fuel sulfur content increases.

SNOX™ takes on these challenges by combing the removal of SOx, NOx, and particulates with commercial-grade sulfuric acid production. This unique process significantly reduces the costs associated with compliance. It also eliminates waste and material logistics, consumes no water or reagents for the desulfurization, and creates a cost-effective alternative to traditional FGD.

Because of the high energy-efficiency of a SNOX™ unit, a boiler, combustor or power plant equipped with SNOX™ will typically achieve an improved energy effectiveness of 5%, which means a drop in specific CO₂ emissions of a similar percentage. Unlike the use of limestone, the SNOX™ flue gas cleaning process does not, in itself, emit CO₂.

The SNOX™ process includes the following steps:

• Dust is removed using electrostatic precipitators or bag filters. Any residual dust will be trapped in the SO2 conversion catalyst, from where it can be removed periodically. (If the dust is combustible, as is the case with soot, dust removal is not required, since the dust will be burned in contact with the catalyst in the SO₂ converter.)
  
  

• Catalytic reduction of NOx takes place by adding NH3 to the gas upstream of the SCR DeNOx converter.
  
  

• Catalytic oxidation of SO₂ to SO3 takes place in the oxidation converter. 
  
  

• The gas is cooled to about 100°C in the WSA condenser, allowing the SO3 to combine with water vapor to form sulfuric acid vapor that condenses and is withdrawn as a commercial grade concentrated sulfuric acid product.
  
  

• The gas can now be sent to stack freed of its sulfur dioxide, NOx, and particulate content.
  
  

• Air that has been used for cooling in the WSA condenser is returned to the boiler, combustor, power plant or other source of the flue gas, where it can be used as preheated combustion air.

The output is the result or end product you're looking to get out of your refinery or chemical process. The output helps determine which technologies and catalysts you need.