Choosing the right flue gas desulfurization and denitrification technology is a key link in achieving emission standards, reducing operating costs and ensuring long-term stable operation of the system. Due to the different flue gas composition and emission requirements in different industries and working conditions, the selection should comprehensively consider factors such as pollutant emission standards, flue gas properties, investment and operating costs, and technical maturity. The following are several aspects that should be focused on when selecting flue gas desulfurization and denitrification technology:
1. Select the technical route according to flue gas composition and emission concentration
The concentration level of SO₂ and NOₓ in the flue gas is an important basis for determining the technology selection. If the SO₂ concentration is high (such as coal-fired power plants or sintering processes), wet limestone-gypsum desulfurization is usually selected. This technology has a high desulfurization efficiency of more than 90%, which is suitable for large volume and high concentration applications. If the SO₂ concentration is moderate, semi-dry desulfurization (such as spray drying) can be considered; while for occasions with low SO₂ concentration or small flue gas volume (such as biomass boilers, waste incineration), dry desulfurization technology, such as dry calcium spray absorption, can be used, with simple equipment structure and low operating cost.
In terms of denitrification, if the NOₓ emission requirements are strict, the selective catalytic reduction method (SCR) is generally used, and the removal rate can reach 70% to 95%; if the emission requirements are relatively loose or cost-sensitive, the selective non-catalytic reduction method (SNCR) can be selected, with a removal rate of 30% to 60%, and low investment and operating costs.
2. Selection based on operating conditions
The temperature, humidity, dust content, and corrosive gas content of the flue gas will affect the applicability of the technology. For example, SCR denitrification needs to keep the flue gas at a temperature of about 300°C, so it is not suitable for low-temperature conditions; while wet desulfurization requires the treatment of a large amount of slurry, which is suitable for large coal-fired units, but has high requirements for corrosion and scaling protection.
In addition, space conditions and difficulty of transformation will also affect the choice. If it is an enterprise with old equipment or limited space, it may prefer dry or semi-dry solutions with small footprint and simple structure.
3. Consider investment and operating costs
The investment and operating costs of different technologies vary greatly. Wet desulfurization has a high investment, but stable operation and resource utilization of by-products (gypsum); dry desulfurization has a low investment, but low absorbent utilization and relatively high operating costs. SCR denitrification has high operating costs, mainly from catalyst replacement and maintenance; SNCR has low costs but limited efficiency.
Enterprises need to comprehensively weigh and select the most cost-effective solution based on their own financial situation, operating capacity and environmental protection requirements.
4. Technology maturity and maintenance capabilities
Technologies with high maturity and wide application are easier to achieve long-term stable operation, low failure rate, and more convenient spare parts supply and technical support. At the same time, the company's own operation and maintenance capabilities should also be considered, whether it has technical support conditions such as maintaining catalysts and managing slurry circulation.
5. Comply with environmental regulations and emission standards
The ultimate goal of selecting a technical solution is to achieve emission compliance. Therefore, it is necessary to take national and local environmental protection standards as the basic basis. For example, when ultra-low emission is required, a high-efficiency desulfurization + SCR system combination is usually required.
In summary, the selection of appropriate flue gas desulfurization and denitrification technology requires comprehensive consideration of flue gas characteristics, emission standards, technical adaptability and economy. In the context of increasingly stringent environmental protection policies, scientific and reasonable technology selection not only helps to achieve sustainable development goals, but also reflects the social responsibility and market competitiveness of enterprises.