Recently, the United States University of Wisconsin Department of Civil and Environmental Engineering Dr. He Ping published "Do not listen to the views of engineers, China three years of haze reactive", the article re-mentioned in 2015 the old article "How long can blue sky and white clouds? An environmental engineer's eyes haze truth ", That the current desulfurization, denitrification measures, especially wet desulfurization, because there is no reheating of flue gas, resulting in low temperature, high humidity flue gas is difficult to spread further aggravating haze.

As an important emission reduction measures for coal-fired power plants, wet desulfurization will really increase the haze? In response, Wang Zhi Xuan, secretary general of China Power Enterprise Federation, said in an interview with reporters that the combination of smoke and humidity haze and the lack of Scientific argument. After the installation of desulfurization and denitrification facilities in power plant boilers, there is no increase of pollutants, but the pollutants are greatly reduced. "If the pollutants are reduced, how will they aggravate the pollution?"

As for the installation of flue gas "reheater" mentioned in the article, Wang Zhixuan said that the vast majority of U.S. flue gas is not heated and that China has adopted wet flue gas emissions at that time did a lot of argumentation, largely to learn American experience In addition, from Germany, "smoke tower technology", the emissions are wet flue gas.

Peng Yingdeng, a researcher at the National Center for Urban Environmental Pollution Control Technology, said that at present, the emission limit of particulate matter in the air pollutant emission standards of thermal power plants is 30 mg / m3, and the special emission limit in key areas is 20 mg / m3. Even as quoted in the article, the fumes and sulphates emitted to the atmosphere by the power plant reached 134 μg / m 3, accounting for only 0.45% and 0.67% of the total particulate emission concentration values, respectively Just trace it. Therefore, the statement that the power plant desulfurization and denitrification process caused a significant increase in haze due to increased emission of sulfate and nitrate from water mist does not hold.

Peng Yingdeng said that the current Beijing-Tianjin-Hebei area in winter heating air pollutant emissions increased by more than 30% above normal, combined with the average winter mixed layer of air more than 30% compression, increased pollution load and environmental degradation of the dual deterioration is nearly ten In winter, the fundamental reason why it is difficult to improve air quality is that the slight adjustment and adjustment in an industry or a certain technical level can not yet shake this predicament temporarily. (Source: ZhongGong)

Review of the old 2015:

How long can this blue sky and white cloud last for this summer? ------ a haze truth in the eyes of an environmental engineer

2015 This summer, I walked through several cities such as Wuhan, Zhengzhou and Beijing. I saw the long absence of blue sky and white clouds, and the bright stars of the sky that night. Circle of friends, many people are also taking pictures of themselves in the blue sky, with a rare joy and surprise.

As an environmental engineer, I know that all this follows the footsteps of nature and science, with no exceptions.

Once known as the pouring girl on the lunchbox of the old man, Chai Jing, the CCTV's poorest host, made an environmental documentary "Under the Dome" at his own expense and took a few days after the fire was quickly banned.

The film mentions the impact of burning coal, car emissions and even dining on smog. Some of the solutions proposed by Chai Jing are reliable, not to comment here, just from the perspective of an environmental engineer to talk about the views of haze.

Haze, must face the problem

Into the 21st century, China's air pollution control efforts have increased year by year, the relevant departments announced the overall trend of air pollutants index is declining. Prospective Industry Institute released "2015-2020 China's air pollution control industry market forward and investment strategic planning analysis report" shows that in 2012, the national emissions of industrial emissions cubic meters (standard), a decrease of 5.8% over the previous year, , Industrial emissions for the first time declined; centralized emissions 368.32 billion cubic meters (standard). In 2013, the national industrial emissions were 61.34 trillion cubic meters, down 3.48% from the same period of last year.

Industrial emissions have been declining year by year in recent years, but in fact, although rare blue sky and white clouds appear this summer, the haze is more and more serious overall, especially in winter.

The main reason haze we really clear it?

To find the main cause of haze, we must start from our energy structure. Ordinary people usually have little access to industries such as energy, petrochemicals and steelmaking. So for the environment, they usually feel like automobile exhaust, sewage discharge and littering. In fact, although these are also part of environmental pollution, they are not Mainly.

Why do you say that although China's auto ownership growth rate is rapid, compared with developed countries such as the United States, it is still small. Developed countries have a very high level of ownership many years ago, but no serious fog like ours haze. The emissions from cars and restaurants are only a fraction of the emissions from coal. Obviously not enough to cause such a serious haze, whether car or restaurant.

In fact, to find the main source of haze, in fact, not difficult, is to look at where our main source of energy, it is easy to find the real reason for haze. Emissions lead to haze, it is undeniable.

China's thermal power accounts for about 80% of the total generating capacity, while hydropower accounts for only about 10%, while new energy such as nuclear power, wind energy and solar energy accounts for only a few percent. Thus, thermal power plants are the major Energy providers, while thermal power is mostly coal-based. The heavily polluting industries such as steel, cement and oil all need coal, without exception. Even the production of fuel for our automobiles requires coal to provide energy or raw materials. All these industries also consume electricity while electricity, 80 About% from coal.

From the data analysis, a ton of coal produces about 2.5 tons of carbon dioxide, China's coal consumption in 2013 was about 3.5 billion tons, about 8.75 billion tons of carbon dioxide. In 2014, gasoline consumption was about 100 million tons and diesel oil consumption was about 160 million tons. The total combustion produced about 800 million tons of carbon dioxide, less than 10% of the coal produced from carbon dioxide. In addition to carbon dioxide, And other impurities, the proportion of gas, it is clear that the vast majority of coal-fired.

Therefore, more than 80% of China's energy comes from coal, and about 80% of its emissions will come from coal. Coal is the main source of pollution.

Coal is the main source of pollution, this is no doubt that this Chai Jing is also mentioned in the film. Chai Jing even put forward measures to reduce coal consumption and increase the proportion of natural gas (this view is actually a problem).

However, as a "coal-rich, less-gas-deficient" country that consumes more energy and has a coal-based energy structure, it is inconceivable that coal will be stopped in the short term and even reduced to only half. That directly led to a nationwide power shortage and the economic blow was self-evident.

Environmental protection how much we have done?

In fact, in recent years, the clean combustion technology for coal-fired thermal power, chemical industry and heating has developed rapidly. Desulfurization and denitrification have become essential equipment. By 2015, almost all thermal power plants are equipped with desulfurization and denitrification equipment, These are very big improvements over a decade ago. Nitride is also one of the causes of haze, so this summer blue sky and white clouds, largely due to this year most of the country's thermal power plants are put into operation flue gas denitrification equipment, greatly reducing the nitride emissions.

The large coal-fired power industry, sulfur dioxide and nitrous oxide emissions have indeed dropped substantially, which is the fact that we can not ignore.

At present, almost 100% of thermal power plants are equipped with desulphurization equipment, most of which are equipped with denitrification equipment. In recent years, hundreds of billions of dollars have been invested in environmental protection by various thermal power plants, and according to the test data of emission targets provided by relevant departments, the declines are indeed declining. From this perspective, the environmental protection department's emission declines year by year seems to be decreasing There is evidence. But why the overall haze is still getting worse? Where is the problem?

Since the beginning of this century, thermal power plants in our country have started to install desulphurization equipment at the end of flue gas discharges. Desulphurization is called as desulphurization island in the industry. In recent years, they have begun to carry out denitrification reforming, that is, removing nitrogen compounds that affect air pollution in flue gas. By 2015, thermal power plant desulfurization and denitrification basically universal.

The problem is: the environmental protection department has been concerned about the number of emissions of flue gas, while ignoring the flue gas temperature and humidity is the problem!

Desulfurization equipment played a discount?

The generation of haze comes mainly from the emission of fumes, either from common sense or from professional tests, which shows that the higher the smoke temperature, the higher the smoke rise and the easier it is to spread. At the same time, the flue gas temperature directly affects the flue gas humidity, the flue gas with greater humidity, the more difficult to spread, the more likely to form smog. Therefore, the temperature of the flue gas has a very important influence on the diffusion.

In the last century, because China did not install flue gas desulfurization equipment, thermal power plant flue gas emissions at temperatures between 130-150 ℃, the flue gas at this temperature are dry flue gas, easy to spread, not easy to form smog. In this case, a large amount of sulfur-containing and nitrogen-containing fumes is discharged into the atmosphere, but generally, the flue gas does not aggregate at low altitude.

This is why everyone in the memory of childhood are blue sky and white clouds, bright stars at night. At that time, although there was no such complicated environmental protection equipment, the temperature of flue gas emission was high and it was not easy to form smog.

In order to control acid rain, this century, environmental requirements have been raised, the introduction of foreign desulfurization technology, flue gas desulfurization began to spread in thermal power plants.

China's energy consumption is mainly coal, the largest coal-fired power plant boiler users. Power plant boilers all on the flue gas desulfurization, and more than 90% of the wet desulfurization, wet flue gas desulfurization temperature of 30-50 ℃ or so, the humidity at 100 ~ 200g / Nm3 (g / standard), and our country The average humidity of the atmosphere is only 9g / Nm3, boiler wet desulfurization exhaust humidity of more than 10 times the average atmospheric humidity, the temperature is 80-100 ℃ lower than before the desulfurization. The total amount of view, according to tons of coal combustion wet desulfurization flue gas with 1 tons of water estimated that China's coal-fired boiler flue gas wet desulfurization annually to the atmosphere about 40 tons of water vapor emissions. In accordance with the chimney design specifications, due to the reduced concentration of pollution fog, wet chimney after desulfurization usually only half of the original height of the chimney, chimney height is reduced, humidity increases, the smoke is difficult to spread.

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