Abstract: The thermal power plant flue gas emissions is the main source of China, will produce large amounts of SO2 and NOx, to the atmosphere caused great harm to the environment. Describes several common current flue gas desulfurization technology, and emerging desulfurization technologies are prospected.
Introduction Anthropogenic emissions into the atmosphere mainly from SO2 and NOx from fossil fuel combustion flue gas. For a long time in China's energy production and consumption structure, has been dominated by coal, this pattern in the relatively long period of time will not change. Large coal combustion flue gas containing SO2 and NOx. SO2 emissions from coal burning in China currently accounts for 90% of SO2 emissions over the power plant is the main gas source. With the yearly increase in installed capacity of thermal power plants and industrial sustained and rapid development, SO2 pollution are not effectively controlled, NOx control has just started, therefore, accelerate the desulfurization and denitrification technologies and equipment, research, development, promotion and application of a current of air pollution control a priority. This article describes several common FGD current technology.
1, several common flue gas desulfurization technology
Currently, industrial applications, flue gas desulphurization technology can be divided into dry (including semi-dry) and wet FGD desulphurization. Dry FGD is to use solid absorbent, adsorbent or catalyst to remove emissions SO2, commonly used methods of activated carbon adsorption, molecular sieve adsorption, oxidation and metal oxide absorption method. The big advantage of dry desulfurization is no waste water governance, the discharge of waste acid to reduce the secondary pollution; disadvantage is that the desulfurization efficiency is low, equipment is huge. Wet flue gas desulfurization scrubbing liquid absorbent to remove SO2, commonly used methods of limestone / gypsum method, sodium alkali absorption method, ammonia absorption, aluminum, catalytic oxidation, and catalytic reduction method.
Wet desulfurization equipment used is relatively simple, easy and efficient in. However, after the flue gas desulfurization at low temperature is not conducive to the spread of smoke.
1.1 limestone / gypsum wet FGD
Limestone / gypsum wet FGD technology is the world's most widely used technology the most mature technology SO2 removal, FGD units installed capacity of approximately 70%. The desulfurization process with high efficiency, high reliability, high efficiency absorbers, large-capacity unit can adapt to high concentrations of SO2 and smoke conditions, coal adaptability, absorbent low-cost, low Ca S ratio (generally less than 1.05) and the comprehensive utilization of the commercial value of products with the characteristics, the main drawback is the high cost of infrastructure investment, covers an area of large, high water consumption, and for the wet desulfurization by-products, it is difficult to handle, and desulfurization wastewater generated can be treated emissions.
1. 2 seawater FGD Seawater FGD is the only one that does not need to add any chemical treatment process, not the amount of solid waste, more than 92% desulfurization efficiency, stable operation, the system can be as high as 100%; with seawater cooling water desulfurization, the economy is good, operation and maintenance costs low; pressure loss, generally 0.98kPa ~ 2.16kPa; structure is simple, easy to operate, easy to automate.
Seawater FGD geographical constraints, only the sea is rich in water resources engineering, especially for sea water for cooling water for thermal power plant; for the desulfurization of seawater alkalinity, pH and salinity higher water quality requirements, etc.; only applies to burning low-sulfur coal used in power plants burning high sulfur coal power plant on its significant increase in the cost of desulfurization precipitator; need to take special anti-corrosion design, properly resolve the internal absorption tower, drainage ditch and the rear absorber flue, chimney, aeration tanks and aeration equipment corrosion problems.
1. 3 Spray Drying Spray drying process (SDA) is a semi-dry flue gas desulfurization technology, its market share second only to wet. The law is the absorbent slurry Ca (OH) 2 in the reaction tower spray droplets in absorption of SO2 from flue gas, while hot gas is evaporated to produce solid capture by ESP. SDA method is more suitable in low-sulfur coal regions, when the calcium sulfur ratio of 1.3 ~ 1.6, the desulfurization efficiency of 80% to 90%. Its main drawback is the use of consumer milk of lime as absorbent, the system easy to scale and congestion, but also specialized equipment Absorbent, which investment costs are relatively large; removal efficiency and sorbent utilization is not as limestone / gypsum high. The technology used mostly in Europe, China had Sichuan Baima power plant in Qingdao industrial pilot and demonstration projects Huangdao desulfurization plant.
1. 4 circulating fluidized bed flue gas desulfurization
Circulating fluidized bed flue gas desulfurization (CFB2FGD) often use lime as the absorbent, the desulfurization spray drying method with a similar principle. The smoke from the air preheater circulating fluidized bed reactor through the bottom of the tower up and lime reaction, a large number of reaction products and fly ash from the flue gas into the reactor to bring back the pre-filter and ESP, most of the solid material back to bed, the final product is dry powder-like calcium-based compounds. Traditional limestone / gypsum desulfurization unit compared, CFB2FGD with simple system, project investment, maintenance and operating costs low, and small size, suitable for existing power plants and industrial boilers transformation. I am a professional writer from China Furniture Manufacturer, which contains a great deal of information about ipod car accessory , delphi xm radio, welcome to visit!
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