ENVI-Clean™ is a patented Emissions Control System designed to remove pollutants from flue gases.
ENVI-Clean™ is suitable for the removal of acid gases and particulate matter from high volume processes such as coal fired power stations, diesel engines and biomass combustion.
It has the efficiency and capacity to do the heavy lifting of sulphur and particulate as well as other acid gases and pollutants in very large applications, but is also cost-effective at a scale suitable for diesel and biomass applications.
ENVI-Clean™ is an advanced wet scrubbing system based on complete and turbulent interaction between exhaust gas and scrubbing fluid, combining:
- Advanced approach to wet scrubbing achieves a single pass solution for acid gases such as SOx and HCI, particulate matter and selected metals,
- Lower operating costs compared to alternative systems,
- Application can be designed for localized/regional regulations,
- ENVI’s approach scrubs 100% of the flue gas at multiple heads, each capable of operating with different reagent fluids to deliver high efficiency pollutant removal and broaden the range of pollutants removed in a single pass,
- ENVI’s reagent management control system minimizes the use of consumables to reduce system operating costs,
- Design allows the flue gas to transit the entire cross-sectional area of the scrubber resulting in a smaller footprint and lower capital cost,
- Scrubber footprint can be adjusted to fit the space available making the system an ideal candidate for retrofit applications,
- Non-hazardous waste water can be processed and reused within the system or for other plant processes such as ash cooling or dust control.
ENVI-Clean™ System for Flue Gas Desulphurization
Acid Gases: The ENVI-Clean™ system with its multi-head configuration provides more contact time for more complete removal of acid gases. Costs are controlled by using lower cost reagents on the first head while polishing to greater than 99% on the second head with more reactive reagents.
Particulate: The turbulent reaction zone at each head level of the ENVI-Clean™ system efficiently transfers particulate matter from the gas to the reagent fluid as a result of the proprietary head design and unique multi-head approach.
Water Use and Waste: The ENVI-Clean™ system produces sludge and wastewater. They can be used in various ways;
- Wastewater is suited for ash quenching/cooling and feed moisture conditioning,
- After dewatering the sludge is suitable for landfill, non-structural concrete stabilization products or combination with bottom ash.
The ENVI-Clean™ Flue Gas Desulphurization (FGD) system installed for the Lianxin Steel Group at their facility near Yancheng in China is designed to remove sulphur dioxide (SO2) from the new power boiler exhaust.
The boiler uses blast furnace gas and coke oven gas as fuel (previously they were flared) to produce steam that powers a turbine to generate 93 MW of electricity. The exhaust gas from the boiler contains up to 250 mg/m3 of SO2 that the FGD system is designed to remove.
The FGD system is centered around a 10m (32ft) diameter 28m (91ft) tall absorber vessel that uses a slurry containing limestone in a froth produced by PGT’s patented head technology to capture the SO2 by absorption. The limestone neutralizes the acids that result from SO2 reacting with water to form gypsum as precipitated solids. The gypsum is removed on a continuous basis by pumping slurry from the absorber reservoir to hydrocyclones to concentrate the solids and then to a vacuum belt filter to produce a gypsum cake. The gypsum can be landfilled or sold.
Ancillary systems supporting the absorber include a gas quench and conditioning zone at the entrance to the absorber, a demister section at the exit of the absorber prior to the 32m (104ft) stack mounted on top of the absorber, a limestone slurry tank and limestone powder silo and feed system, a recirculation pump system, an oxidation air system, various sumps, water tanks and pumps, a process control system and a continuous emission monitoring system.