With the continuous development of society and the continuous expansion of cities, the treatment of domestic waste has become a major problem in urban development. Internationally, there are three main ways to deal with domestic waste: incineration, sanitary landfill and composting. Sanitary landfill is currently the mainstream waste treatment in China, the process is simple, but also easy to cause surface water and groundwater pollution. Moreover, with the continuous growth of China's population, land is becoming more and more scarce, and the landfill method seems to have come to an end. In the face of the dilemma of garbage besieging the city, many cities have begun to consider incineration to generate electricity to dispose of garbage.
Launched a special report, focusing on China's southwest region of the waste incineration power generation enterprises in the plant operation, flue gas treatment of advanced experience
Chongqing Fengsheng waste incineration power plant wastewater treatment system using "biochemical + ultrafiltration + reverse osmosis (RO)" process treatment to meet the national standards, in the plant After reaching the national standard, the wastewater is used for watering flowers and raising fish in the plant.
The garbage is thrown into the furnace and burned, the metal is not decomposed, but is separated out in the slag treatment system, and can still be recycled.
After the garbage is incinerated, the slag can be recycled and made into bricks and other building materials, which are widely used in municipal road construction.
Editor's note: In recent years, the city's urban expansion and quality of work continues to accelerate the city's development, population growth resulting in more and more urban garbage. It is understood that the city's average daily generation of domestic garbage in the 600 tons or so, and the city's only landfill - Qilongkeng landfill has tended to be full. How to solve the increasing amount of domestic garbage, to protect the ecological environment of Meizhou? A few days ago, the reporter came to Chongqing City, Chongqing Fengsheng Environmental Protection Power Plant in Sanfeng Chongqing, to see how the operation of this more than four years of waste incineration power plant is operating.
Incineration power plant as beautiful as a garden
In the eastern part of the mountain city of Chongqing Municipality, there is an ancient town of Fengsheng, surrounded by mountains and pleasant scenery. In this town, is located in southwest China's largest construction of modern waste incineration power plant - Sanfeng Environmental Chongqing Fengsheng environmental power plant. The plant was put into operation in June 2012 in Banan District, Chongqing, put into operation for four years, the plant has accumulated 3.5 million tons of garbage, the use of waste incineration to generate more than 1.2 billion degrees. "At present, one-third of the domestic garbage in the main city of Chongqing is processed by the plant." Guo Linhan, a staff member of Chongqing Fengsheng Environmental Power Generation Co., Ltd. of Sanfeng Environment, said that through standardized operation and refined management, the Fengsheng plant has been named one of the top ten environmental protection education bases in China, and is also a national primary and secondary school environmental education social practice education base designated by the State Ministry of Environmental Protection and the Ministry of Education. It receives many visitors every year.
Standing in front of the Fengsheng plant, if not pointed out, outsiders would never have thought that this is a waste incineration power plant. Into the plant, everywhere birds and flowers, green trees, in a red flowers and green grass, long factory road production plant, dormitory, dining hall and other buildings in series between, this is just like a garden-style plant. Walking in the factory, it is difficult to smell the unpleasant smell, except for the sound of machines running in the production workshop, there is no difference with other factories. In front of the factory, there are automatic deodorant sprayer constantly spraying deodorant to the door, in order to eliminate the stench brought by the garbage compression truck. Guo Linhan introduced, Fengsheng plant can handle 2,400 tons of domestic garbage every day, the average daily power generation of about 1 million degrees, 10% of the plant's own use, the rest of all on the national grid, for more than 200,000 urban households daily electricity. "This truly realizes the transformation of domestic waste into clean energy." Guo Linhan said that because the factory produces all day long, many staff members live in the factory dormitory all year round, which they consider home.
Advanced technology to deal with 'Chinese' garbage
How can a waste-to-energy plant be transformed into a national environmental education base? This seems to subvert the public perception. The reporter was led by the staff to visit the whole process of waste incineration.
Inside the 26,000-square-meter garbage storage pit, nearly 20,000 tons of domestic garbage are stored, which can be used for a week's production at the Fengsheng plant. "After the garbage is carried to the plant by compressed transportation vehicles and dumped into the garbage storage pit, it needs to be stacked for 3-5 days in order to allow the garbage to ferment and remove moisture for burning." Factory workers introduced, then the garbage by the grapple put into the temperature of 1000 ℃ furnace fully incineration, and then through the process of removing harmful gases, adsorption of dioxin, and finally to the slag collection and leachate treatment. Reporters found that this series of operations are completed by machinery, and its secrets in the plant's central control room. The reporter saw here that the equipment is running around the clock, and the data of the furnace temperature, rotating spray tower and bag filter and other equipment are displayed here. It is understood that the plant has a very high degree of automation, which is conducive to controlling the amount of garbage into the furnace, the furnace temperature and the emission of pollutants.
Technicians at the Fengsheng plant told reporters that China's garbage has a high moisture content and a low calorific value. In order to make the "Chinese" garbage can be burned better, the three peaks of the company from Germany to introduce a mature technology to be absorbed after the transformation, the formation of the current set of technology. It is understood that the introduction of the three peaks of the company is the world's most widely used German Martin SITY2000 waste incineration power generation full set of technology, the emission indicators have reached the current EU environmental standards. Guo Linhan said, Martin's technology is used to push back the tilting reciprocating grate furnace, the technology is characterized by direct combustion of unsorted garbage, without the addition of any auxiliary fuels.
In the incinerator assembly base of Chongqing Sanfeng Environmental Group, the reporter saw many parts of the grate furnace, which is one of the world's largest assembly plants of waste incineration equipment, and every year the grate furnace equipment is exported to Europe and the United States, and this technology is currently used in more than 40 cities at home and abroad in 79 waste incineration power generation projects. The plant's technical staff introduced this mature equipment, each part has a number, so that the future maintenance can be traced back to its roots.
1The garbage trucks are weighed into the plant and then the garbage is dumped into a garbage storage pit, where the garbage is stored for three to five days, with about 20 percent of the water filtered out. When the garbage is fully fermented, a mechanical grab takes the garbage to an incinerator for burning. The leachate produced by the garbage is then sent by a special pipe to the wastewater treatment system for treatment.
2After the garbage enters the incinerator, it is pushed onto the grate by a feeder to be burned, and the whole combustion process can be divided into four stages, namely, drying, combustion, combustion and cooling, which takes about 1.5 to 2 hours. About 15% of the slag remaining after the waste is ignited can be used for paving or brick making after cooling by a wet slagging machine. The flue gases remain in the furnace chamber at over 850°C for more than 2 seconds to ensure complete decomposition of the dioxins. Meanwhile the urea solution sprayed in the boiler flue removes nitrogen oxides from the flue gas. The heat generated during the incineration process heats the water in the boiler into water vapor, which pushes the turbine-generator unit to generate electricity.
3 Flue gas purification system. Semi-dry flue gas treatment technology is used, and the main equipment is a rotating spray tower and a bag filter. The lime slurry sprayed into the rotating spray tower removes acid gases such as hydrogen chloride, hydrogen sulfide, hydrogen fluoride and sulfur dioxide, while the activated carbon sprayed into the tower adsorbs heavy metals and small amounts of dioxins that may be present in the flue gas. In the bag filter, the dust particles contained in the flue gas are filtered and intercepted. After strict purification, all the emission indexes reach the EU 2000 environmental protection standard.
4Finally, the fly ash collected in the baghouse dust collector is treated with chelating agent curing and then sanitary landfill or used for manufacturing glass and other building materials after special treatment.
China's technology international leading
After years of development, waste incineration power plants are gradually spread throughout the country. But the domestic commonly implemented incineration and pollutant treatment technology compared with foreign countries how, the people are most concerned about the "dioxin" problem is how to deal with? The reporter specifically interviewed the Chongqing Municipal waste incineration power generation experts in the field - Chongqing Institute of Science and Technology Professor Zhou Xiong.
Reporter (hereinafter referred to as the record): At present, China's waste incineration technology at a level of what line?
Zhou Xiong (hereinafter referred to as Zhou): Before China's grate technology is not adapted to the "Chinese" garbage treatment, China's garbage moisture, low calorific value, 1 ton of garbage in the past can only send 270 degrees of electricity, which indicates that the garbage is not fully combusted. Now, according to Chongqing, Chengdu and other southwest waste incineration power plant operation, 1 ton of garbage can send 350 degrees of electricity, testing shows that this has reached a complete combustion.
In the flue gas treatment, through the urea, lime, activated carbon and chelating agent, can be effectively dealt with the pollutants, flue gas emission standards have reached the international leading level. In addition like garbage leachate by biological plus membrane method after strict treatment can be used for watering flowers, fish; incineration slag can be used as building materials; fly ash curing landfill or used as production of building materials.
Note: the people are generally concerned about the "dioxin" problem, we can effectively control?
Zhou: At present, according to the southwest of Chongqing and other waste incineration power generation enterprises in the operation of the situation, "dioxin" problem has been well controlled. It is widely recognized that high temperature can effectively decompose dioxin. After years of experience, the furnace temperature (controlled at 850 ° C to 1050 ° C) can effectively remove dioxin, in addition to the flue gas in the cooling process (temperature of 500 ° C to 200 ° C), dioxin will be synthesized again, which requires that our process is a rapid cooling. At the end of the process, dioxins can be adsorbed through activated carbon. This is the current international advanced treatment method, we are in the actual operation of the process, "dioxin" control is even stricter than the European Union.
The evolution of incineration
Currently, there are three types of household waste treatment: incineration, sanitary landfill and composting. From the point of view of the treatment process, sanitary landfills are easy to operate, but there are environmental problems such as occupying a large amount of land resources, improper management of surface water and groundwater pollution, bad odors and breeding mosquitoes. Waste incineration power generation can maximize the realization of waste "harmless, reduction, resource". In the waste incineration method, the most widely used, the most environmentally friendly is the mechanical grate furnace waste incineration power generation technology, which can not only greatly reduce the volume of garbage, the rapid removal of a variety of hazardous substances, but also to bring us a steady stream of clean energy.
It is understood that the world's earliest waste incineration plant was built in 1876 in Manchester, England. Early incinerators are mostly fixed-bed type, low level of mechanization, in and out of the material also rely on artificial, waste incineration is not sufficient, the smoke emissions will pollute the environment.
After more than 100 years of evolution and innovation, from the earliest simple incineration, to the realization of waste heat utilization, and then to purify the flue gas to focus on environmental protection emissions, waste-to-energy has become the world's most mature developed countries and the most common way to deal with waste, waste-to-energy power plant has become a landmark building in some famous cities. In developed countries and regions in Asia and Europe, most of the waste-to-energy plants are built in the built-up areas or city centers. For example, France, Paris, Saint-Ouen garbage power plant, built on the banks of the beautiful Seine River; the world's music capital of Vienna, Vienna Spitlaw waste-to-energy plant, built in the city center of Vienna; and Taipei's Beitou waste-to-energy plant, the chimney on the construction of a rotating restaurant and observation deck, the plant built sports parks and swimming facilities, and has become the public's recreational areas.
China's domestic waste incineration power generation industry, although a late start (began in the last century, the late 1990s), but due to strong state support, the development of faster. At present, the country has built and put into operation nearly 200 power plants, the daily processing scale reached 150,000 tons.
Originally published as "Advanced technology to deal with domestic waste"/news/201609/3595.html