In coal-fired power plants, SOLVAir products effectively reduce SO2, SO3, HCl and mercury (Hg) emissions, and, additionally, provide some reduction in NOx
Our products are sodium based, and have benefits for Electrostatic Precipitator performance, which allow the addition of particulate loading without causing opacity excursions. For baghouse applications, the added retention time increases sorbent efficiency.
In coal-fired boilers, sulfur is oxidized to SO2 during combustion, and a small percentage (1%) is further oxidized to form SO3. Nitrogen is also oxidized to form various oxides, referred to collectively as NOx.
When flue gas is cooled across the air heater, the SO3 combines with flue gas moisture to form gas-phase sulfuric acid (H2SO4) where it can condense at temperatures below 350°F. Concentrated H2SO4 can accumulate at cold spots on air heater baskets or downstream. This can lead to a severe corrosion of the installation.
The use of Selective Catalytic Reduction (SCR) units for NOx control further oxidizes SO2 to SO3 and can double the amount of SO3 present. This added level of SO3 can be enough to form a blue plume of sulfuric acid out of the stack that can persist for miles.
For units equipped with wet scrubbers, the sulfuric acid vapor condenses as a mist at the scrubber inlet. While wet scrubbers can remove gas-phase SO2, they are not effective at removing the condensed sulfuric acid.
The sulfuric acid leaving the scrubber is a fine mist that scatters light very effectively, and makes for a more visible plume.
Mercury and other heavy metals are also released from coal upon combustion. Chemical absorption of these metals on materials like Powdered Activated Carbon (PAC) or fly ash is reduced by the presence of SO3.
The treatment of SO2, SO3, NOx and mercury has become a high priority for coal-burning utilities.
SOLVAir products can be utilized in a dry injection process in the flue gas stream. These systems are low capital cost options to meet the treatment needs of coal-burning utilities, and equipment can be installed quickly for trials or permanent installations.