GEA Niro’s Spray Dryer Absorber (SDA) is a process developed to remove acidic pollutants, heavy metals and dust from flue gases of various origins, primarily fossil fuelled power stations, waste incinerators and steel industries. The process has its origin in spray drying and consists basically of a spray dryer absorber module , a GEA Niro rotary atomizer , a downstream dust collector and an absorbent feed preparation system.
The hot, untreated flue gas is introduced into the absorber module via the gas dispersers for optimum gas flow distribution and contact with the absorbent sprayed by the rotary atomizer. The efficient contact between the gas and atomized absorbent slurry allows for rapid mass transfer of acidic components from the gas phase into the liquid phase. The alkaline absorbent neutralizes the absorbed acid and the desired reaction product is formed while water is evaporated simultaneously. A fraction of the dried end-product drops to the bottom of the absorber chamber and is discharged, while the main part is taken to the downstream dust collector with the cooled flue gas, and removed from the gas. The clean gas passes from the dust collector to the stack without re-heating.
All flowsheet animations are available in the GEA Niro download area. The GEA Niro SDA process uses slaked lime Ca(OH)2 as absorbent and produces a dry end-product mainly consisting of fly ash and various Calcium salts. The absorbent is either purchased directly as slaked lime or – more often and more economically - prepared from burned lime CaO on site. From a buffer tank, the slaked lime is pumped to the rotary atomizer by which it is atomized to droplets of less than 50 microns. Following the absorption of acidic components, the chemical reaction and the final drying, the powdery end-product is separated from the gas phase and transported either to an end-product storage facility, or re-used in the SDA process for improved utilization of excess absorbent.
The SDA technology features excellent performance for absorption of not only the primary pollutants like SO2 and HCl, but due to the combination of finely sprayed absorbent into the flue gas stream and the subsequent dust removal, a pollutant like SO3 is removed practically 100%, allowing the use of carbon steel as construction material throughout the entire flue gas path. Other features of the GEA Niro SDA process are that it allows use of low quality process water, such as waste water or even sea water, and that the process generates no waste water.
The end-product from the process is a stable and dry powder and is used for a variety of purposes. Although it can be used as an absorbent in wet type
FGD plants, the majority of the SDA product produced throughout the world is re-used in road construction, building materials, and for other purposes in the construction industry.
The unique implementation of spray drying technology for acid gas absorption was originally invented by GEA Niro in the 1970’s, and has ever since continuously been further developed and optimized to meet changing conditions and requirements. The GEA Niro SDA process stands therefore as an efficient, versatile and mature technology.
SPECIAL FEATURES:
- High acid gas removal efficiencies
- High plant availability
- Low capital cost
- Low power consumption
- Low operating and maintenance cost
- Low water consumption
- Utilize low water quality
GEA NIRO SDA REFERENCES:
- Total plants built: 112
- Total number of absorbers: 230
- Total number of atomizers: 326
- Process installed at 10.400 MWe and 4.300 MWt power plant capacity
- Process installed at more than 100 incineration lines worldwide