The garbage classification work in Guangzhou is in full swing. Many citizens know that a lot of the sorted garbage is transported to terminal treatment facilities-- �Thermal power plant, How do garbage burn and convert it into clean electricity when it comes here? How to deal with harmful substances and toxic gases produced after incineration?
Recently, the reporter visited the Guangzhou Fifth Resource Thermal Power Plant to explore the entire process of garbage from fermentation, combustion, treatment of harmful gases to thermal energy conversion. At the Fifth Resource Thermal Power Plant in Guangzhou, the daily garbage processing capacity reaches 2,250 tons, and the annual power generation is 360 million kWh, which can be used by 100,000 households in one year. The nitrogen oxides produced after combustion are chemically reacted to become harmless water and nitrogen, and the flue gas is purified through a purification system to achieve emission indicators that are better than national standards. The non-combustible slag is made into environmentally friendly bricks for municipal engineering construction.
Only after dehydration and fermentation can it be burned
The Fifth Resource Thermal Power Plant is equipped with 3 mechanical incinerators that can handle 750 tons of garbage per day, and the incinerator is equipped with a grate. The garbage is dried, ignited, burned, and burned thoroughly through the grate until it is burned.
Guangzhou No. 5 Resource Thermal Power Plant is located in Shibaling area of Chini Town, Huadu District, surrounded by jungles. The storage pit outside the operating workshop on the sixth floor of the power plant is piled with garbage from all over Huadu District, and these garbage will be stored here for 3 to 5 days. A relevant person in charge of Guangzhou Environmental Protection Investment Group told reporters: "The garbage that has just been transported has a large moisture content. It must be dried in this storage pit before incineration."
The reporter saw that the storage pit was a large transparent sealed space. Due to its good sealing properties, the odor produced by the garbage would not be emitted outward. A grab bucket was installed above the storage pit. An operator was operating the grab bucket, stirring the garbage in the pit and filtering out the sewage. The garbage leachate is pumped to the leachate treatment plant for treatment through the leachate. "Store garbage for a few days will also help garbage fermentation, increase calorific value, and facilitate combustion." The person in charge said.
After the garbage is dehydrated and fermented, the operator then uses a grab bucket to send the garbage into the hopper of the incinerator, and the hydraulic pusher will push the garbage into the incinerator.
Toxic and harmful gases are purified before being discharged
During the garbage combustion stage, harmful substances and toxic gases such as nitrogen oxides, hydrogen chloride, sulfur dioxide, and dioxins will be produced in the incinerator furnace. After the treatment process of "SNCR denitrification + semi-dry deacidification + activated carbon adsorption + bag dust collector", the emission indicators are better than the national standards.
"The furnace temperature is as high as 850℃~1100℃, and high temperature can decompose some harmful substances and toxic gases." The person in charge said that when the flue gas passes through the outlet of the incinerator, the treatment system will inject air into the outlet and replenish the oxygen required for secondary combustion. Turbulence will form at the outlet of the incinerator, so that the flue gas from the incinerator can be fully recombusted in the secondary combustion chamber.
In addition, refractory materials are also laid around the furnace and the secondary combustion chamber, allowing the flue gas to stay in the combustion chamber above 850°C for more than two seconds. "Under the action of high temperature, the dioxin-like toxic substances produced during the combustion process can be fully decomposed." For nitrogen oxides in the flue gas, the treatment system will spray ammonia water into the middle area of the secondary combustion chamber, causing the nitrogen oxides and ammonia water to undergo a redox reaction to produce harmless nitrogen and water.
After the nitrogen oxides in the flue gas are removed, they enter the flue gas purification system. These high-temperature flue gases after denitrification must first be cooled by a waste heat boiler and then enter the deacidification tower. The lime mortar in the tower reacts chemically with acid gases such as hydrogen chloride, sulfur dioxide, fluorine chloride, etc. in the flue gas to produce harmless salt and water.
According to the relevant person in charge of Guangzhou Environmental Protection Investment Group, activated carbon will also be sprayed into the flue behind the deacidification tower to adsorb dioxins and heavy metal particles. Finally, the bag dust collector is used to intercept the fly ash particles in the flue gas and the activated carbon that absorbs dioxins and heavy metals. The fine mesh of the bag dust collector can separate the dust from the flue gas. Finally, the purified gas is transported to the chimney through the induction fan and discharged into the air. After the treatment process of "SNCR denitrification + semi-dry deacidification + activated carbon adsorption + bag dust collector", the emission indicators are better than the national standards.
Bricks made of waste heat energy generator slag
The Fifth Resource Thermal Power Plant's daily domestic waste treatment capacity reaches 2,250 tons, annual domestic waste treatment 750,000 tons, and annual power generation of 360 million kWh, which can be used by 100,000 households in one year.
It is understood that there is a waste heat recovery boiler behind the incinerator. The boiler uses the high-temperature flue gas generated by waste incineration to heat the water into medium temperature and medium pressure water vapor, which drives the
Steam turbine generatorThe group generates power. "This way, the heat energy generated by waste incineration can be converted into clean electricity." The person in charge said. Each ton of garbage can generate more than 400 degrees of electricity. Except for the electricity consumed by the production electricity in the factory, the remaining electricity is transferred to the Southern Power Grid and enters thousands of households.
In addition, domestic waste contains certain amounts of sludge, tiles, stones, etc. These substances will produce a certain amount of slag after being incinerated. The Fifth Resource Thermal Power Plant transports the generated slag to a nearby slag plant to make environmentally friendly bricks for municipal engineering construction. After the resulting fly ash is solidified, it will be transported to a landfill for special area landfill.
According to reports, the Fifth Resource Thermal Power Plant has enabled Huadu District, Guangzhou to achieve daily daily clearance and zero landfill.
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