At present, incineration is an important domestic waste treatment method. It has been applied in many cities in China. It also has the effect of generating electricity and surfing the Internet while burning garbage. It is a kind of garbage disposal method that is very suitable for China's national conditions. In recent years, domestic waste incineration has generated electricity. The rapid increase in volume has mainly analyzed the key factors of the amount of electricity generated by domestic waste incineration power plants, and hopes to help the future work.

The average value of tons of garbage on-grid electricity in China's domestic waste incineration power generation enterprises increased by 42kW·h between 2011 and 2018. According to the annual on-grid electricity/year-to-plant waste volume as the calculation index, the average average on-grid electricity consumption of waste incineration power generation enterprises in 2018 was 283 kW·h, which was 16% higher than that in 2011. Shenzhen's energy and environmental protection tons of on-grid electricity increased from 227kW·h in 2010 to 293kW·h in 2018, and the on-grid electricity consumption increased by 66kW·h. The main influencing factors of tons of on-grid electricity are many, but the core reason is the improvement of the calorific value of domestic garbage and the improvement of waste incineration technology. Among them, the calorific value of domestic garbage is the key factor driving the increase of power generation in waste incineration; technological progress is an important supplement to the increase in electricity generation per ton.

1 The increase in the calorific value of domestic waste is the main reason for the increase in electricity generation per ton.

In recent years, the amount of on-grid electricity in waste incineration enterprises has increased significantly. The industry generally has an increase in the amount of electricity generated per ton, and the large-scale enterprise increase is particularly obvious. The other major waste incineration listed companies have also significantly increased their on-grid electricity consumption in the past two or three years.

1) The calorific value of domestic waste is one of the key factors affecting the amount of electricity generated by waste incineration. The content of light combustible components (mainly including paper, fabric, plastic) has a decisive influence on the calorific value of domestic waste.

2) In economically developed areas, the calorific value of domestic garbage is generally high. In China's Pearl River Delta, Yangtze River Delta, and Beijing-Tianjin regions, there are projects with a relatively high amount of electricity on the Internet.

3) Garbage sorting and collection promotes the improvement of people's living standards, which increases the heating value of urban domestic waste and increases the amount of electricity on the Internet:

(1) Waste separation and collection advancement: The moisture content of the remaining garbage will decrease with the increase of the classification rate of biomass waste. Taking Shenzhen as an example, with the promotion of domestic waste classification, kitchen waste is reduced year by year, when biomass waste is classified. When the rate is 20%, the low calorific value of the remaining garbage will increase by 4465kJ/kg from 4419kJ/kg; if the biomass waste classification rate reaches 39%, the low calorific value of the remaining garbage will reach 7000kJ/kg.

(2) The improvement of people's living standards has naturally increased the calorific value of domestic garbage: in China, the incombustibles in garbage have been decreasing year by year and the combustibles have increased year by year. The calorific value has increased rapidly in the past decade. With the economic development and the improvement of people's living standards, the calorific value of domestic garbage has increased. The calorific value of domestic waste depends on the nature of the various wastes that make up the waste and its proportion. The main contribution to the net calorific value is fixed carbon, moisture and volatiles. The main component of fixed carbon is carbon, and its calorific value is the heat of combustion of carbon; moisture has a negative contribution to the calorific value, mainly considering its latent heat of evaporation; and the calorific value of volatile matter is closely related to the proportion of plastic in the garbage. The content of light flammable components (mainly including paper, fabric, plastic) has a decisive influence on the calorific value of domestic garbage. Although at present, the amount of electricity generated by waste incineration projects in China's economically developed areas and tons of on-grid electricity have reached a high level, compared with developed countries, there is still room for improvement. The amount of electricity generated by household waste incineration in the United States is above 600 kW·h. The high-tonnage power generation is behind the high calorific value brought by the classification of waste. The domestic calorific value of domestic waste can reach twice the current average level in China. In China, the promotion of garbage collection and the improvement of people's living standards have made the heating value of urban domestic garbage in the process of upgrading, which has led to an increase in the amount of electricity on the Internet.

2 Technological progress is also an important reason for the increase in data on electricity generation per ton

Grate furnace technology is fully promoted, advances in waste pretreatment, feeding, sorting and incineration technologies, as well as improvements in waste incineration equipment technology, especially the application of waste incineration boiler technology for medium-temperature and high-pressure steam parameters, bringing tons of new construction projects Further increase in power generation.

3 grate furnace technology is more expensive than fluidized bed technology, and grate furnace technology has become mainstream in China.

1) The grate furnace has a good treatment effect on the block material, and there is no excessive requirement for the pre-treatment of the garbage. Therefore, the mechanism of the material storage is relatively mature and very simple, and the garbage can be obtained by the flipping of the grate. Fully burnt, in the combustion, can add solid or liquid supplement fuel for combustion, and the combustion system is now more and more mature. In addition, its slag removal system is very stable. It can maintain a stable state during combustion, and the control is convenient. Through comparison between Everbright International, Shenzhen Energy Environmental Protection, Green Power (Grate Furnace Technology) and Jinjiang Environment (Culcanized Bed Technology), it can be seen that the grate furnace technology is more than the fluidized bed technology. There is a significant advantage in power.

2) From 2010 to the first half of 2018, the proportion of project capacity using fluidized bed technology in the country has dropped from 49% to 21%.

4 medium temperature sub-high pressure steam boiler can promote power generation efficiency

The thermal efficiency, operating cost, manufacturing cost and income of the incinerator are all directly affected by the steam parameters. For waste incineration plants, 4.0MPa, 400°C, 6.5MPa, 450°C, 5.3MPa, 450°C are generally used. As the main parameters of the waste heat boiler. The Likeng Waste-to-Energy Plant is the first in China to apply the medium-temperature sub-high pressure condition technology to the waste heat boiler. For comparing the above two working conditions, it is a simple calculation under the condition that the external conditions are determined. In the case of different conditions, the ratio will also change, but there is no significant difference in the comparison trend. For the sales revenue, the secondary high temperature and high pressure scheme has more advantages. However, it has higher boiler equipment cost and operation and maintenance cost. Based on the comprehensive analysis of the 25a operation, the medium temperature and high pressure have good economic effects. Therefore, in China's new incineration plant, the use of 6.5MPa, 450 °C, 5.3MPa, 450 °C parameter steam boiler has been promoted. At present, the application of high-nickel alloy steel and other corrosion-resistant materials in the superheater makes the life of the superheater effectively extended. Although it has a high investment cost in one-time construction, it has a good comprehensive benefit. Therefore, this parameter Has a good application prospects.

1) With the medium-temperature ultra-high pressure technology, the first pit of Likeng has reached 6900-7100kJ/kg in 2017, and the power generation of 1t garbage reaches 350-360kWh.

2) The first phase of Shenzhen Pinghu Waste Incineration Plant passed the medium-temperature medium-pressure technology, and its waste heat value has reached 6 900kJ/kg. The power generation per ton of garbage waste is 290kW·h. Compared with the current domestic waste heat value, compare domestic waste incineration. The steam parameters used in the waste heat boiler of the plant are the medium-temperature medium-pressure parameters (400 °C, 4 MPa) and the medium-temperature secondary high-pressure parameters (450 °C, 6.5 MPa), indicating that the higher the steam temperature, the higher the power generation efficiency, the medium temperature and the second high pressure. The power generation of waste heat boilers increased by 17%.

5 Conclusion

The promotion of waste sorting and the improvement of people's living standards have led to an increase in the calorific value of domestic waste and the advancement of incineration power generation technology, which has led to a significant increase in the amount of on-grid electricity in the industry, and an increase in power generation revenue for waste incineration enterprises. The improvement in earnings will surely lead more companies to enter the wave of waste incineration and power generation, and continue to promote the further development of the industry.