Ministry of Environmental Protection to develop a new "power plant air pollutant emission standards" over comments will be formally introduced, NOx (nitrogen oxide) emissions targets to achieve the world's most stringent control level. Denitration project started with urea as a reducing agent denitrification, with their easy to transport, storage, security and low cost advantages in power plants and denitrification in the ass.
NOx is one of the major air pollutants, directly or indirectly affect the quality of atmospheric environment, such as photochemical smog, atmospheric acid deposition, stratospheric ozone depletion, etc. In addition, the increase in the amount of nitrogen deposition will lead to eutrophication of surface water and land , wetlands, groundwater acidification and poisoning, which both terrestrial and aquatic ecosystems, damage, and ultimately to human health and the environment adversely affect safety.
NOx and other thermal power plants is a major source of air pollutant emissions, according to Chinese Academy of Engineering Research, China's environmental capacity of 1,200 tons of nitrogen oxides. To 2009 emissions data, the power industry had only 1,400 tons of nitrogen oxide emissions, and emissions continues to increase. In order to control NOx air pollution, the ministry asked the thermal power industry, focusing on the development of industrial NOx pollution control. In Beijing, Tianjin, the Yangtze River Delta and Pearl River Delta region, the new thermal power plant construction and denitrification devices must be synchronized, before the end of 2015, active denitrification unit completed the transformation. The new "thermal power plant air pollutant emission standards," added four mandatory emissions targets that include nitrogen oxides.
China's thermal power plant NOx emissions control is still in its infancy, relying on low-NOx combustion technology can not meet NOx emissions control requirements, the need for flue gas denitrification. Denitration denitrification technology in the most efficient, most mature is the selective catalytic reduction (SCR), is the flue gas NOx in the catalyst, reacts with reducing agent and generate toxic nitrogen and water pollution . Main sources of NOx reducing agent are ammonia, ammonia and urea, ammonia as a reducing agent in which there is a certain risk, use less foreign. Ammonia is a chemical classification of dangerous goods in class 2 and 3, the occupational exposure to harmful levels of toxic levels of IV (mild damage), is flammable, explosive, toxic substances. In the country, according to the "major hazard identification" requirement, the use of ammonia in excess of 40 tons, has become a major hazard.
Huaneng Beijing Thermal Co., Ltd. Production manager Ducheng Zhang said, the ideal source of urea is ammonia, which is a stable, non-toxic solid materials, are harmless to humans and the environment, can be bulk transport and long-term storage. It does not require special transportation and storage procedures, its use and will not adversely affect the surrounding community, safety and low cost. Recently in the U.S. market, ammonia and urea ammonia as an alternative to more and more for denitration project.
The new standards require, for new and January 1, 2004 to December 2011, 31 environmental impact assessment approved by the full implementation of existing coal thermal power plant boiler flue gas denitrification, after the implementation of 2015 will need to add smoke gas denitrification capacity of 817 million kilowatts. Currently, the South China Sea has long Sea Power Company Limited, GD Datong No.2 Power Plant and other plants more and more use of urea SCR transformation as a reducing agent.
Huaneng Yuhuan power plant in January this year, NOx transformation, the first time the use of urea particles in pneumatic conveying tests are successful, the delivery of urea particles in the compressed air to rapidly enter the urea granule storage, test the success of the NOx reducing agent - urea into a more efficient way of feeding, pneumatic conveying clean way, the use of urea as a reducing agent for our large-scale thermal power plant denitrification system has provided valuable practical experience.
Beijing Environmental Protection Engineering Co., Ltd. China Long Yuan Electric engineers Bin Shen told reporters, because of the power plant efficiency of denitrification is not the same and other factors, it is difficult unity of urea used in denitrification is the number, some 300,000 kilowatts of generating units consume 370 kg per hour, about urea. Be sure to use urea in stock than smaller, more does not endanger the agricultural use.
Experts, urea can also desulfurization and denitrification. Reaction of sulfur dioxide and urea ammonium sulfate, purified gas can be discharged directly, ammonium sulfate as a fertilizer for sale, urea derivatives and ammonia used for desulfurization and denitrification can also be co-production of cyanuric acid. This mode of operation, small footprint, no secondary pollution, the product of comprehensive utilization, desulfurization and denitrification investment and low running cost, in line with circular economy, sustainable development concept. (Zhang Xinggang)