Wet electrostatic precipitator: a blue sky in China
Smog blocks out the sky and the sun. It's hard to scold!
The past goes on for thousands of years. Apart from other factors, the Chinese people living in the natural environment of the middle ages were happy - in the face of green mountains and green waters, morning and sunset, Qin Guan, the poet among them, could chant such beautiful words as "the fog lost the building, the moon lost its way, and there was no way to return to Taoyuan. The poor solitary hall was closed in the cold of spring, and the setting sun in the sound of cuckoos".
Now, a ferocious word "haze" has replaced the "haze" that has always given Chinese people elegant romance.
Since January 9, 2013, China's central and eastern regions have fallen into serious haze and pollution days. The Central Meteorological Observatory has upgraded the fog blue warning to yellow warning. On the 13th, Beijing issued an orange haze warning in Beijing's Meteorological History, and the air pollution index was close to 1000 micrograms.
In the past two months, the haze weather in Beijing, Tianjin and Hebei has been serious. This kind of haze weather is not the first time. Just take Beijing as an example. In the past two years, the air quality in Beijing has been moderately and severely polluted for at least 30 days in winter, but PM2 5 close to 1000 micrograms, but it is rare.
Not only that, from North China to central China, there has been a wide range of severe and serious pollution in the Huang Huai and Jiangnan regions. Smog shrouded the sky over 1.43 million square kilometers, affecting more than 800 million people.
On the morning of January 29, when the haze was serious, airports such as Beijing, Xinzheng, Qingdao and Hangzhou were seriously affected. According to the information from the road network center of the Ministry of transport, the continuous haze weather in central and eastern China has blocked the passage of some 30 Expressway sections in Beijing, Tianjin, Hebei, Shandong, Hunan and Hubei. The monitoring shows that many sections of the main transport channels such as Beijing Shanghai, Beijing Taiwan, Beijing Hong Kong Macao, Rongwu, Qingdao Yinchuan, Lianhuo, Shanghai Chongqing Expressway were closed for a short time, and the affected sections basically resumed traffic around noon on the same day. If the losses of transportation and enterprises are added to the loss data, which far exceeds the value of GDP 3%, the annual loss of more than trillion yuan will become the norm.
On January 14, the Asian Development Bank and Tsinghua University released the report "towards an environmentally sustainable future - Environmental Analysis of the people's Republic of China". According to the report, the annual economic loss caused by China's air pollution is estimated to be equivalent to 1.2% of GDP Based on disease cost and 3.8% based on willingness to pay. In 2012, China's total GDP was 51932.2 billion yuan, reaching 623.2 billion yuan at 1.2% and 1973.4 billion yuan at 3.8%.
Therefore, academician Zhong Nanshan issued a shocking warning: "smog" is more photographed than "SARS"!
Such a serious ecological disaster has aroused great concern of the central government.
On January 15, at a grassroots Research Symposium, Vice Premier Li Keqiang pointed out that "the problem of air pollution accumulation is a long-term process, and solving the problem also needs a long-term process, but we must make a difference!"
meanwhile, Wu Xiaoqing, Vice Minister of the Ministry of environmental protection, stressed when answering reporters' questions: "The process of air pollution prevention and control at home and abroad shows that solving the problem of serious air pollution is a long-term and arduous work. It took 30-50 years for developed countries such as Europe and the United States to basically solve the problem of air pollution. We should correctly deal with the current situation of air pollution, fully understand the difficulty, complexity and long-term nature of improving the quality of the atmospheric environment, and be prepared to fight a protracted war."
Will contemporary Chinese people live in the shadow of smog for such a long time?
Fortunately, Jiangsu Best Environmental Engineering Co., Ltd. has achieved a breakthrough in industrial dust removal from quantitative change to qualitative change.
Enlightenment from a scheme demonstration meeting of "wet electrostatic precipitator"
Haze locks China, and the culprit is dust
The causes of haze and haze weather are complex. Fine particles are suspended in the atmosphere, resulting in air turbidity and reduced visibility, resulting in haze weather. Among them, fine particles with a diameter less than or equal to 2.5 microns and less than 1 / 20 of the thickness of human hair are called PM2 5, also known as particulate matter that can enter the lung.
PM, the full English name is particulate matter. Scientists use PM2 5 represents the content of such particles per cubic meter of air. The higher this value is, the more serious the air pollution is.
PM2. The standard of 5 was proposed by the United States in 1997, mainly to more effectively monitor the small particles harmful to human body that appear with the increasing development of industrialization and are ignored in the old standard. PM2. 5 index has become an important index for measuring and controlling the degree of air pollution.
PM2. 5. The main source of production is the residues discharged through combustion in the process of daily power generation, industrial production and automobile exhaust emission, most of which contain toxic substances such as heavy metals. Generally speaking, coarse particles with a particle size of 2.5 microns to 10 microns mainly come from road dust; Fine particles below 2.5 microns (PM2.5) mainly come from the combustion of fossil fuels (such as coal, motor vehicle exhaust), volatile organic compounds, etc.
China's primary energy is mainly coal. In recent ten years, China's coal output has increased from 1.47 billion tons in 2001 to 3.52 billion tons in 2011, with an average annual compound growth rate of 9%. Among them, coal consumption in industrial production has always occupied an important position in China's total coal consumption, maintaining more than 94% all year round. Power generation and coking are the main uses of industrial coal, accounting for 50% and 15% of industrial coal respectively. Coal fired power plants are important sectors that emit sulfur dioxide, nitrogen oxides and soot. With the continuous increase of the proportion of coal converted into electricity, most coal-fired emissions will be more converted into electricity emissions. The proportion of sulfur dioxide emission from electric power accounts for 42.4% of the total sulfur dioxide emission in China, nitrogen oxide emission accounts for more than one third, and soot emission accounts for 36.7%. Control the flue gas emission of coal-fired power plants to reduce PM2 5. It plays a great role in alleviating urban air quality.
At present, 90% of China's electric energy comes from thermal power generation, which needs to burn a lot of coal. In 2012, China's total consumption of industrial coal was about 3.7 billion tons, and thermal power generation consumed 1.85 billion tons of electric coal. In the process of combustion, one ton of coal will produce 30 kg of smoke and dust (0.03 ton). Then, after 1.85 billion tons of coal are burned, about 5.55 million tons of coal ash will be produced, and five thousandths of the coal ash will be PM2 5. It will also produce 2775 tons of PM2 5。
In January and February this year, China's PM2 5 more than 1000 micrograms per cubic meter have been found in serious places, while the average in the United States is less than 15 micrograms per cubic meter, and only 50-70 micrograms per cubic meter in the seriously desertified Sahara desert. Global PM2 The five regions are all in North Africa and North, East and central China.
So, is PM2 caused by vehicle exhaust emission 5. Is the pollution so serious?
At present, China's car ownership is increasing, but the total is not much. The United States still has a large car ownership. At the end of 2011, the total number of motor vehicles in China was 219 million, including 80 million cars and 285 million cars in the United States, 3.5 times that of China. China's PM2 The content of 5 is about 5 times that of the United States.
Still in 2004, PM2 in urban air in China The content of 5 has been among the best. At that time, China's car ownership was much lower than that of the United States, but PM2 5 is much higher than that of the United States, which indicates that PM2 5 is not mainly from vehicle exhaust emissions.
To sum up, China PM2 5. The main reason for serious exceeding the standard is daily power generation and other factors (China is a large coal-fired country).
In a city with such serious air pollution, in order to improve air quality and reduce the probability of haze weather, many coal-fired power plants should be built or relocated to more remote areas, so as to reduce urban pollution and facilitate the diffusion of smoke and dust in the air. However, this method can only move away from the pollution source, and can not solve the problem of PM2 in smoke 5, and the disharmony with the residents around the power plant due to air pollution can not solve the problem of air pollution.
Therefore, if the dust emission of coal-fired power plants is reduced, the above problems will be greatly solved.
Why can wet electrostatic dust removal technology remove PM2 efficiently 5 dust?
According to the relevant data provided by foreign companies, wet electrostatic precipitation technology is used to treat PM2 in power plant dust 5. The removal effect is 99%. It can be seen that the wet electrostatic precipitator has the high-efficiency treatment of PM2 that other conventional electrostatic precipitators do not have 5 functions.
The main working principle of wet electrostatic precipitator: spray the water mist to the discharge electrode and corona area. The water mist splits and further atomizes after being charged in the powerful corona field formed by the awn electrode. The collision, interception, adsorption and coagulation of electric field force and charged water mist jointly catch the dust particles. Finally, the dust particles reach the dust collecting electrode and are arrested under the drive of electric field force. The water forms a continuous water film on the dust collecting electrode, which washes the captured dust into the ash hopper and discharges it with the water. Wet electrostatic dust removal technology is to remove PM2 5 is the current international level dust removal and environmental protection technology. In Europe and the United States and other developed countries, hundreds of projects have applied wet electrostatic dust removal technology to effectively remove PM2 from flue gas 5 dust.
Therefore, wet electrostatic precipitator can effectively remove submicron particles and fog droplets with particle size as small as 0.01 μ M. the dust removal efficiency can generally reach more than 99.9% according to the number of operating electric fields.
According to relevant foreign literature, the main product wet electrostatic precipitator is resistant to acid mist, toxic heavy metals and PM10, especially PM2 5 fine dust has good removal effect. Wet electrostatic precipitator can be used to control SO3 acid mist in power plant, which has the prospect of combined removal. The research and application of wet electrostatic precipitator abroad have proved that the arrangement of wet electrostatic precipitator after wet desulfurization system can effectively remove PM2 in flue gas 5 dust, SO3, mercury, oxides and other pollutants.
Wet electrostatic precipitator is used to control PM2 of coal-fired flue gas 5 very effective equipment, which has been widely used in developed power and other engineering fields. The test reports of Bruce Mansfield power plant, mirant'dickerson power plant and other power plants in the United States show that the wet electrostatic precipitator is effective for PM2 The removal efficiency of 5 is higher than 95%, and the dust emission concentration is lower than 5mg / Nm3.
Nowadays, most domestic power plants are located in suburbs. If the dust emission of power plants is reduced, a large number of relocation funds will be reduced. In terms of the whole country, this fund will be in the unit of 100 billion yuan. The wet electrostatic precipitator can greatly reduce the emission of dust and reduce PM2 5, reduce the probability of haze weather, so as to greatly alleviate air pollution.
In addition, wet electrostatic precipitation technology can be applied not only in coal-fired power plants, but also in coal-fired boilers, chemical industry, metallurgy and other fields. These applications have achieved very good results in Europe and America. If used on a large scale in China, it will also produce huge social and economic benefits.
Technology is a powerful tool to solve pollution
China's coal reserves. According to the second coal field prediction data in China, the total coal resources buried more than 1000 meters above the stratum are 2.6 trillion tons, and the coal reserves in Shanxi alone are more than some of the total reserves.
On the other hand, China is relatively short of oil and natural gas, which determines that our energy and power must rely on extremely abundant coal resources for a long time.
Since we cannot bypass the coal power industry, we must find a way to solve its pollution.
Application of wet electrostatic precipitator in removing PM2 5. Based on the introduction of technology and combined with the technical characteristics of China's coal-fired and power generation industry, Jiangsu Best Environmental Engineering Co., Ltd. has carried out the technical research and development of wet electrostatic precipitator for coal-fired boiler, established a strategic cooperative relationship with Zhejiang University, participated in the subject of combustion flue gas pollutant control in the "863" plan, and independently designed and manufactured a domestic comprehensive experimental platform for wet electrostatic precipitator The domestic production of key components of wet electrostatic precipitator is implemented on the test and research platforms such as multi-functional hot dust removal test-bed, large air flow physical model test-bed, physical and chemical analysis test-bed and CFD numerical simulation laboratory. Demonstration project of the Ministry of environmental protection - Liuheng power plant 2 affiliated to zheneng × The wet electrostatic precipitator project of 1000MW coal-fired unit is being implemented.
The new wet electrostatic precipitator developed by Jiangsu Best Environmental Engineering Co., Ltd. controls PM2 after wet desulfurization 5. Controlling SO3 acid mist and removing mercury and other heavy metals, on the one hand, the rapping is cancelled to avoid the secondary flying of dust. The emission concentration of smoke and dust can be controlled below 5mg / m3, which also greatly reduces PM2 5； On the other hand, it can also effectively control SO3 acid mist, mercury and other heavy metals. Humidified by spray inside the electrostatic precipitator, the particle size of the charged SO3 acid mist increases under the action of electrostatic condensation, which is trapped on the electrode plate and forms dilute acid with the water film. The removal efficiency can reach more than 95%. At the same time, based on the internal supersaturated environment and electrostatic removal effect of electrostatic precipitator, the removal efficiency of particulate mercury and mercury oxide in flue gas is more than 60%.
In addition, the new wet electrostatic precipitator can be combined with wet flue gas desulfurization equipment to solve the problem of flue gas emission after desulfurization, and can be applied to the removal of acid mist aerosol after ammonia desulfurization, the efficiency improvement of hemp water film dust collector, the capture of fine particles in iron and steel industry, as well as the smoke and dust removal and PM2 emission reduction of ceramic, glass, metallurgy and other kilns 5 up.
