With the continuous development of the economy and urbanization, all kinds of garbage emissions are increasing day by day, and the problem of "garbage siege" has become one of the major problems faced by countries around the world. Therefore, the research and development of waste treatment technology, especially waste incineration power generation technology, has become a major trend of global development and stability in the future.
Of course, it is a matter of pride that the mainland's waste incineration power generation technology is currently in a leading position in the world, and the waste-to-energy plants built in China can process more than 3 million tons of garbage a year without burning coal, and the power generation can reach 1.5 billion, which is a technology that even the United States has not yet achieved. So what exactly is waste-to-energy technology? Does waste-to-energy pollute the environment? What are the challenges if the technology is to be rolled out on a large scale?
An introduction to waste-to-energy generation
The so-called waste power generation refers to the use of special incineration boilers to incinerate and treat various solid waste, and then through the professional steam turbine generator set for power generation of a special form of power generation. This method of power generation has been around since the 1970s, when some developed countries in Europe and the United States built waste-to-energy power stations to study technologies for generating electricity using the heat generated by incineration.
By the beginning of the 21st century, more than 1,000 waste-to-energy stations had been built around the world, and compared with many developed countries, the mainland's waste-to-energy technology started relatively late. However, in recent years, with the strong support of the mainland's comprehensive national strength and national policies, the mainland's waste incineration power generation technology has developed rapidly. In particular, the waste incinerator technology independently developed by the mainland has been developed from a fixed grate waste incinerator to a circulating fluidized bed boiler, which has impressed many Western countries.
At present, the category of waste-to-energy generation is mainly divided into two ways: waste incineration power generation and landfill power generation. Then many people wonder, is all the garbage can be used to generate electricity? In fact, before using garbage to generate electricity, it is necessary to first collect all kinds of garbage in a unified manner, and then classify and treat the garbage one by one.
That is to say, in the process of garbage classification, some garbage that can burn but has no recycling value will be sorted out, and then the garbage will be broken up to make a dry burning ball similar to a coal ball. These combustion balls are then fed into a special high-temperature incinerator using advanced machinery, and the heat energy is converted into high-temperature steam through high-temperature incineration, which pushes the turbine to rotate at high speed, so that the generator generates electrical energy.
For the garbage and substances that cannot be burned in the garbage classification, special fermentation, anaerobic and other methods are used for treatment, and then through drying and desulfurization technology, it produces methane gas, which is commonly known as biogas, and then burns the biogas, so that the thermal energy is converted into steam, which also promotes the rapid operation of the turbine, so that the generator generates electrical energy.
In the process of garbage classification, the garbage that can be recycled will be recycled reasonably and efficiently. In this way, in just a few hours, a lot of garbage that originally needs to be disposed of in landfills can be turned into people's production and living electricity, and then transported to thousands of households through the power grid.
Does waste-to-energy pollute the environment?
It is true that with the rapid development of the modern economy, the global waste production is increasing, and the pollution caused to the environment is becoming more and more serious, as if the garbage flood has become a major problem of global concern. According to relevant data, the annual garbage production of mainland cities is about 1 trillion tons, and the annual cost of garbage transportation and treatment is about 30 billion yuan. If these wastes can be used for power generation, according to the average low calorific value of 2900kJ/kg, it is equivalent to 14 million tons of standard coal.
That is to say, garbage power generation can not only solve the problem of "garbage siege", but also deal with millions of tons of garbage every year, reduce the huge garbage space, but also allow waste reuse, create more than one billion kWh of electricity every year, and greatly alleviate the current shortage of energy such as coal in the country.
In summary, the use of waste incineration to generate electricity is indeed the best way to solve the garbage problem, and many countries are constantly developing and improving the relevant technologies of waste power generation. However, many people are beginning to worry that in today's global warming, will this waste incineration power generation cause more pollution and damage to the environment?
Because the waste incineration power generation process will inevitably produce a lot of harmful gases and substances, such as: various particulate pollutants, heavy metals, acid gases, highly toxic organic pollutants, ash residue, dust and landfill. Among them, the emission of dioxins has attracted widespread attention, because dioxins are one of the most toxic pollutants known to mankind so far, and they are also internationally recognized as first-class carcinogens. Generally, the temperature of incinerated garbage at 300-500 °C will form dioxins during the combustion process of the tail channel.
The answer to the question of whether the various pollutants produced in the process of incinerating waste power generation will pollute the environment is that as long as the incineration of waste power generation is properly controlled and rigorous, its impact on the environment is very small. First of all, this is a new high-end technology to build a power generation method, not only for the garbage can be fully burned and filtered, but also set up a tightly sealed garbage dump warehouse, effectively preventing environmental pollution.
Secondly, at present, the waste-to-energy plants built on the mainland not only have independent patented technologies, but also carry out more than ten processes of automatic purification and detection of harmful pollutants such as waste gas and wastewater generated during the garbage combustion process, and only when the specified emission standards are met, green discharge will be carried out.
In other words, compared with the pollution and damage caused by simple landfill treatment of garbage, waste incineration power generation is more environmentally friendly and safe, and the triple goal of harmlessness, reduction and energy saving has been achieved.
The current situation and prospect of waste incineration power generation in mainland China
At present, in the face of the problem of garbage flooding, in addition to the use of defensive measures to control and destroy garbage, the world has also actively taken measures such as garbage power generation to scientifically and effectively realize the comprehensive treatment and utilization of garbage.
Since the introduction of waste incineration power generation technology in Shenzhen in 1985, the mainland's waste power generation technology has developed very rapidly, until today, the mainland's waste incinerator technology has basically achieved localization, and many equipment, spare parts and training have basically achieved automatic innovation and research and development. Moreover, in recent years, more than ten cities such as Zhuhai, Hangzhou, Shanghai, Shaoxing and other cities on the mainland have also built a number of waste incineration power plants and have been fully put into operation, at the same time, many waste power plants can achieve the task of incinerating 1,000 tons of garbage per day.
As far as the Shanghai Laogang Renewable Energy Utilization Center project, the largest combustion waste-to-energy power plant currently built in the mainland, is a waste-to-energy plant built by the mainland using a new patented technology, which is currently divided into phase I and phase II, the first phase of which was put into use in May 2013, and can process about 3,000 tons of garbage per day. Since the second phase was put into use at the end of September 2019, its daily waste disposal capacity can reach about 6,000 tons, and its daily power generation capacity is more than 3 million kWh.
That is to say, Shanghai as a large city with a population of more than 20 million, its daily garbage production is very large, according to the 2017 data survey, Shanghai average daily output of 24,700 tons of domestic garbage, Shanghai resident population of nearly 24 million, which means that Shanghai's annual garbage production is more than 9 million tons.
After the second phase of the Laogang Renewable Energy Utilization Center was put into use, it basically treated one-third of the amount of garbage in Shanghai, which not only greatly alleviated the garbage occupation space and saved energy, but also with the continuous maturity of the waste power generation technology of the Laogang Energy Center, its emission standards were far below the specified standards. According to the technical staff of the Laogang Energy Center, the current emission standards of an incinerator in the second phase can basically be equivalent to the emissions of a car.
Although the development of waste-to-energy generation technology in the mainland is very good, there are also many problems and challenges in technological development. First of all, the promotion of garbage power generation is constrained by regional and seasonal changes, and it is easy to implement in developed cities in the east, and it can greatly reduce the problem of urban garbage, but it is difficult for remote and backward cities to temporarily implement them due to technology, funds and other reasons. In addition, the calorific value generated by combustible garbage is relatively low, resulting in large fluctuations in the generation of dian and poor power stability.
Secondly, the operating costs of waste treatment equipment, incineration boilers and power generation equipment are very expensive, and the electricity generated by waste power generation is poor, its income is low, and it is impossible to achieve independence, so it still needs strong support from national policies, and there is still a long way to go on how to further improve research and development and improve waste incineration power generation technology.
In addition, for the harmful gases and polluting substances generated in the process of waste incineration power generation, it is still necessary to continuously improve technology and strengthen detection mechanisms to maximize environmental friendliness and sustainable development.
In short, the current waste-to-energy stations built on the mainland and the country's waste-to-energy generation technology are leading in the world, which is something to be proud of. However, there are still many deficiencies in the calorific value generated by the mainland's waste power generation, incineration technology and equipment, etc., and it is hoped that in the near future, the mainland can design and develop a perfect waste incinerator to fully realize the harmlessness, reduction and resource of garbage. So as to completely turn garbage into energy, and give the earth a sense of tranquility!