Our products range from flue gas scrubbers for power stations to complex flue gas cleaning systems for Energy-from-Waste plants. Thanks to a wide product portfolio, innovativeness in engineering and long experience in executing projects, ANDRITZ has the right solution to meet all environmental and financial goals.
Maintaining the energy efficiency of your processes, complying with the strictest licensing procedures, and developing tailor-made solutions for your plant are the cornerstones of ANDRITZ's approach.
Air pollution control technologies introduction
Wet flue gas cleaning systems
Limestone flue gas desulphurization (FGD) units are well-proven and cost-effective. ANDRITZ provides novel scrubber system (FGDplus) that maximizes SO2 and dust removal while keeping energy inputs to a minimum.
Dry flue gas cleaning
ANDRITZ dry flue gas cleaning systems meet the requirements for complying with the world’s strictest emissions legislation, the desire for low consumption of additives, the need for minimal residues, and the installation simplicity of a compact design.
ANDRITZ dry flue gas cleaning systems are well proven one-step cleaning solutions in a very compact design. They are equally suited to be used downstream of coal and oil-fired boilers, as well as biomass, RDF, or domestic and industrial thermal waste treatment plants.
DeNOx systems - Selective Catalytic Reduction (SCR)
ANDRITZ Air Pollution Control was among the first companies in Europe to successfully employ Selective Catalytic Reduction (SCR) technology. The company now has numerous references in the DeNOx/SCR sector, which encompass a variety of applications. In addition to use in power plants (high dust configuration), we also have successfully employed selective catalytic reduction (SCR) technology for waste incineration and other industrial processes.
Combined/multi-stage flue gas cleaning systems
Our complete product portfolio allows us to comply with the most difficult requirements through the intelligent combination of our processes and technologies.
Current legislation regarding waste disposal and emissions levels require state-of-the-art flue gas cleaning systems. Selective pollutant removal is required, which not only aims to achieve minimum emissions in tandem with low operating costs, but also enables the recovery of recyclable by-products and a linked reduction in the volume of highly pollutant residues.
We offer air pollution control technologies for
- Power stations
- Industrial plants (including energy-from-waste plants and biomass plants)
- Shipping/maritime industry
ANDRITZ air pollution control products meet the requirements for complying with the world’s strictest emissions legislation, the desire for low consumption of additives, the need for minimal residues, and the installation simplicity of a compact design. Quite often, our systems are delivered turnkey to ensure single-source accountability and efficiency.
Cutting-edge engineering tools and global R&D collaboration with a network of recognized partners and universities lay the foundation for our work. Early identification of each client’s needs help ANDRITZ make a long-term contribution to clean air and a clean environment.
Seawater FGD (Flue Gas Desulphurization)
ANDRITZ offers seawater flue gas desulphurization with low operating and maintenance cost for coastal regions.
Based on extensive experience with limestone FGD since 1995, we developed a seawater flue gas desulphurization process for use in power plants in coastal areas by taking full advantage of the cooling water circuit downstream of the condenser.
Ideal solution for coastal plant
ANDRITZ´s seawater FGD system is able to work without additional absorbent, and there are no by-products or waste created that need further treatment or disposal. Raw flue gas enters the scrubber and is cleaned in counter-current by seawater.
The principle applied here is similar to the limestone process. Depending on the application ANDRITZ offers an FGD scrubber based on the well proven open spray tower technology, combined with an FGDplus system. In addition, ANDRITZ also has experience with a packed tower design for seawater FGD systems. These systems are beneficial in optimizing the plant’s footprint and efficiency at high SO2 inlet concentrations.
Wise principle
The principle of our process is to make use of the natural alkalinity of seawater instead of using limestone solution to absorb acidic substances in the flue gas. The SO2 is first converted into sulphite. Then the sulphite is oxidated to form sulphate in the CFD-optimized aeration basin in order to maintain the pH, raise the DO (dissolved oxygen), and reduce the COD (Chemical Oxygen Demand). In the meantime, CO2 formed by the neutralization reaction is stripped by aeration membranes, and the pH value is increased consequently to meet legal requirements.
Key features
- Outstanding for various fuels (lignite, hard coal, oil, and biomass)
- Up to 99% SO2 removal
- No by-products
- Seawater as absorbent
- Open spray tower technology and packed tower design
- Low operating and maintenance costs
- High availability
Options for materials of construction (high-alloy carbon steel with rubber lining, concrete with PP-lining, glass fiber reinforced plastics)
Mercury control
Holistic approach to minimize mercury emissions throughout the process chain
Of the several processes for removing mercury from the emissions of coal-fired power stations, the most preferred are those that have synergy with existing air pollution control equipment.
Mercury is a potentially deadly neurotoxin. Mercury emissions from coal-fired power stations are a major environmental concern due to the toxicity and persistence of mercury that accumulates in our waterways.
Stringent mercury emission limits in the USA and upcoming BAT and IED regulations in Europe present a significant challenge. To meet these limits, ANDRITZ follows a holistic approach by taking not only the various oxidation reactions in the flue gas pathway into account, but also the processes within the wet FGD system and downward streams. We expect that this issue will become a major topic worldwide for coal-fired boilers within the next few years.
Flow Sheet_Mercury Control
If the conventional oxidation in the gas phase, based on the gas condition and process set-up, is not sufficient to meet the emission limits, ANDRITZ offers a well-proven calcium bromide oxidation system. Dosing calcium bromide into the boiler is an adequate and easy way to oxidize the greater part of the mercury originating inside the boiler. Other process steps within the flue gas path are crucial for any further mercury oxidation downstream of the boiler as well. For instance, any enhanced oxidation within an existing SCR unit has to be considered for any process developments. Finally, the oxidized mercury will be captured at the FGD scrubber. ANDRITZ considers all the important process steps and the gas composition in order to optimize the mercury emission control system implemented.
ANDRITZ is also looking into the documented topic of potential corrosion effects in combination with the bromine-induced mercury oxidation. Corrosion effects have been documented in some plants, especially in the USA. It was found that corrosion will occur primarily at the cold part of the cold side of the air heater in cases where unusually high bromine concentrations were added to the coal mill and the process set-up was not favorable. Bromine is not unusual in flue gas. It is found in any coal containing halogens. In general, the bromine content in coal will be roughly 1 to 3 % of the chlorine content. With a chlorine content of between 1000 and 2000 ppm in the dry coal, this means that the bromine content in the same coal will be between 20 and 40ppm.
This is also the effective operating range that ANDRITZ recommends for any additional bromine dosage to the coal. Thus, corrosion effects as a result of additional bromine being added can be excluded.
The wet FGD is not only a very efficient way of separating acidic components from the flue gas stream, it is also highly efficient when it comes to removal of the oxidized mercury species. However, inconsistencies in wet scrubber chemistry can be linked to re-emissions of mercury that has already been captured. In order to avoid any re-emissions from the FGD process, ANDRITZ focuses particularly on binding and stabilizing the dissolved mercury in the limestone slurry. If, for instance, PAC (powdered activated carbon) injection is applied to inhibit re-emission, the main mercury sink in the conventional process chain will be the FGD by-product – the gypsum. This is unacceptable for two major reasons if the plant management is targeting beneficial use of the FGD product. Firstly, it greatly increases the mercury content in the gypsum, which could render the FGD product useless as a resource for the drywall industry. Secondly, the gypsum whiteness will deteriorate and hence be unattractive for commercial use.
With conventional hydrocyclone systems, the specifically bound mercury cannot be removed efficiently from the gypsum. Thus, ANDRITZ offers a patented hydrocyclone design that clearly separates the mercury-loaded particles (e.g. PAC) from the gypsum and thereby reduces the mercury content in the FGD product to a minimum. This patented wash water hydrocyclone technology is easy to implement and has a clear advantage for any upgrade of existing FGD installations for any upgrade of existing FGC installations in order to enhance mercury transfer to the waste water treatment plant and also to prevent an increase in the mercury concentration within the scrubber.
ANDRITZ offers an upgrade of any mercury reduction system with a clear mercury sink within the FGD system and can draw on long-term experience with any dewatering technology. Thus, a controlled mercury sink is created.
Source: Andritz AG
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