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Basic Knowledge Of Waste Incineration Power Generation Project!
- May 31, 2018 -

Domestic waste incineration project construction overview

With the gradually development of urban living garbage incineration industry in China, the number of operation of incinerators increase year by year, has increased from 2000 years before the two fast at the end of 2015 to 224, burned total scale of 207800 tons/day, accounts for about 40% of the disposal ability, garbage disposal ability get improved.

Distribution from incinerator was put into operation, the southeast coastal area facilities construction progress significantly ahead of the central and western regions, including zhejiang, shandong, jiangsu, guangdong, fujian in the number of incineration facilities and incineration facilities ranks the top processing scale, the five provinces in incineration facilities have been built 129, accounting for 57.6% of the total national incineration facilities, this proportion is far more than the central and western areas.


Main characteristics of waste incineration technology

1. Save project land.For the same amount of waste, incinerators need only 1/20-1/15 of the area of landfills.

2. Fast processing speed.Waste sanitary landfill in the decomposition time usually takes 7 to 30 years, and of the rubbish incineration as long as the melting point is lower than 850 ℃, 2 hours can be processed.

3. Good reduction effect.The same amount of waste can be reduced by about 30% by landfill, 60% by compost and 90% by incineration.

4. Low pollution emissions.According to research and measurement by Germany's leading environmental research institute, if the same stringent eu pollution control standards are adopted, the pollution generated by waste incineration is only about 1/50 of that of sanitary landfill.

5. High energy utilization.Each ton of garbage can be burned to generate electricity of more than 300 degrees, and about every 5 people can produce household garbage. By burning electricity, one person can meet the daily electricity demand.

Generally speaking, for large and medium-sized cities with dense population, developed economy and scarce land resources, priority should be given to waste incineration.


Policies, standards and regulations issued for waste incineration projects

Living garbage incineration power plant construction, has the strict construction examination and approval procedures, including the characteristics of franchise bidding procurement, for examination and approval of conformity of the planning, land use, environmental impact assessment, assessment, assessment and social stability evaluation, etc.At the same time, in order to ensure the construction level and construction quality of domestic refuse incineration power plants, the state has formulated and promulgated and implemented relevant policies, standards and norms for garbage incineration power plants, including:

1. Notice of approval of the state council to the ministry of housing, urban-rural construction and other departments on further strengthening the work of municipal solid waste disposal (issued by the state council [2011] no. 9);

2. Notice on further strengthening the management of environmental assessment of biomass power generation projects (unced [2008]82);

3. Notice of the general office of the state council on the issuance and issuance of the 12th five-year plan for the construction of harmless treatment facilities for municipal solid waste in China (guo ban fa [2012] no.23);

4. Standard for control of pollution caused by incineration of domestic waste (gb18485-2014);

5. Control standards for the coordinated disposal of solid waste by cement kilns (gb30485-2013)

6. "standards for construction of municipal solid waste incineration and disposal project" (construction standards 142-2010);

7. Technical specifications for incineration and treatment of domestic waste (cj90-2009);

8. Technical specification for waste incineration bag-type dust removal engineering (hj2012-2012);

9. Technical guidelines for domestic waste fluidized bed incineration engineering (RISN -- TG16), etc.

In order to regulate the operation of domestic refuse incineration power plants, the standards and norms have been promulgated and implemented, including:

1. Evaluation standard of domestic waste incinerator (CJJ/ t137-2010);

2. Operation supervision standard of domestic waste incinerator (CJJ/ t212-2015);

3. Technical specifications for operation, maintenance and safety of domestic waste incinerator (cj128-2009);

4. Technical guidelines for evaluation of domestic refuse fluidized bed incinerator (RISN -- tg018-2015)


The main technology used in domestic waste incineration

Garbage power generation is the collection of all kinds of garbage, classification treatment.High temperature incineration is carried out for high combustion value. The heat energy generated in high temperature incineration is converted into high temperature steam, which drives the turbine to rotate and generates electric energy for the generator.For not burning organic matter, anaerobic fermentation processing, finally dry desulfurization, methane gas is methane, then through the combustion heat energy is converted to steam, turn a turbine, drive the generator to produce electricity.

The main technologies of waste incineration power generation mainly include five types of technologies, including mechanical incinerator, fluidized bed incinerator, rotary incinerator, CAO incinerator and pulse incinerator.At present, the main domestic waste incineration technologies are mechanical furnace discharge technology and fluidized bed technology.

Working principle of the mechanical grate incinerator: waste through the hopper into the downward sloping grate, because of staggered movement between the grate, the garbage to the push, make rubbish in turn by the regions on the grate, until burning furnace.Combustion air from the lower part of grate into and mixed with garbage, high temperature steam by heating surface of boiler flue gas heat, smoke also get cool at the same time, the last out the back of flue gas by the flue gas treatment device.

Fluidized bed incinerator working principle: the furnace body is composed of porous distribution board, to join in the chamber of a stove or furnace lots of quartz sand, quartz sand heated to above 600 ℃, and the bottom blowing above 200 ℃ hot air, make the hot sand boil, put in the garbage.Rubbish boils with hot sand, which is quickly dried, caught on fire and burned.Not burning garbage weight is lighter, continue to boil burning, burning garbage proportion bigger, fell to the bottom of the furnace, after cooling, the coarse slag and fine slag with separation equipment to the factory, a small amount of secondary slag and quartz sand by lifting equipment back to continue to use in the furnace.


How to control emissions

The waste gas from incineration plants mainly comes from the flue gas produced during incineration. Its main pollutants are dust, hydrogen chloride, sulfur dioxide, nitrogen oxides, dioxins and heavy metals.

Through the computer control system can realize waste incineration, heat energy utilization, the height of the flue gas treatment process automation, control of combustion conditions (temperature higher than 850 ℃, the flue gas residence time is greater than 2 seconds, etc.), make the burning system running under the rated conditions, the original concentration of emissions to a minimum, and ensure the dioxins thoroughly decomposition of organic matter.

Install all kinds of efficient flue gas treatment equipment, such as bag dust removal, activated carbon adsorption of harmful substances, etc., and the use of continuous monitoring each incineration flue gas monitoring instrument online of line of flue gas emissions targets, to ensure the incinerator flue gas pollutants discharge standard requirements.


How to control odor emissions

1. The compressed transport vehicle with good sealing and automatic loading and unloading structure should be adopted to transport garbage and minimize the overflow of odor.

2. An air curtain shall be set at the entrance and exit of the garbage unloading hall, and the electric discharge door shall be closed before and after the unloading of the garbage truck to prevent the odor from escaping.

3, rubbish should be closed design, set up over the cesspit exhaust opening, drew the stench gas as the combustion air to pyrolysis incinerator, and makes the cesspit and unloading hall in the negative pressure state.

4. The spare activated carbon waste gas purification facilities should be set up. During the overhaul of the whole plant, the odor in the garbage pond must be purified by the activated carbon waste gas purification facilities to the standard before it can be discharged.

5. The leachate treatment system shall be designed as a closed structure, and a guide pipe shall be set on the top to decompose the generated methane and odor gas into the incinerator at high temperature through the guide pipe and fan.


How to control dioxin emissions

It is often said of dioxins is actually short for dioxin-like substances, refers to the structure and properties are similar contains many other objects or the isomers of two kinds of organic compounds, a total of 210 species, in which only a few species are credited with toxicity.

Dioxin is not a specific hazard to incinerators. It is a compound produced when organic materials are heated with chlorine. It is a common chemical phenomenon.Dioxins can be found in air, soil, water, food and garbage. Some studies have shown that food is the main source of dioxins.

The waste incinerator controls the dioxin emission, keeps the temperature in the incinerator chamber greater than 850 degrees, and keeps the flue gas in the chamber for more than 2 seconds, so that the dioxin can be completely decomposed.The other is that through the advanced purification treatment system, the concentration of unit dioxin is controlled within 0.1nac, reaching the strictest international emission standards.


How to dispose slag and fly ash

Slag is mainly for the living garbage incineration residue after the quantity depends on the composition of garbage, its main components in manganese oxide, silica, calcium oxide, 3 oxidation 2 aluminium, ferric oxide, scrap metal, and a small amount not burning of organic matter, etc.Waste incineration slag produced by high temperature disposal, isolated by magnetic separation and other waste metals such as iron and steel scrap, may carry on the comprehensive utilization of slag, such as paving the way for the cushion layer, cover material of landfill, etc.

Fly ash is hazardous waste and must be collected separately. It must not be mixed with household refuse, incineration residue, or other hazardous waste.Waste incineration and fly ash shall not be stored in the factory for a long time, shall not be disposed of simply, and shall not be transported or discharged at will.Must first be necessary in the factory of MSW fly ash stabilization and solidification process, in the stabilization and solidification processing and after leaching toxicity test qualified, can use a dedicated airtight transportation sent to safety landfill or sanitary landfill dumps.Where conditions permit, other treatment and disposal methods in accordance with the standards may also be adopted.


How to dispose of leachate

Leachate belongs to high concentration organic waste water, which needs to be discharged through a special multi-channel purification process.The amount of leachate production is mainly affected by the composition, water content and storage days of the garbage.Leachate has the following characteristics: complex and variable pollutant composition, large change in water quality, high concentration of organic pollutants, high concentration of ammonia nitrogen, high content of heavy metal ions and salt.

At present, there are many processes used in wastewater treatment, but special requirements have been put forward due to the high concentration and complex composition of leachate.Generally speaking, the basic process of the garbage leachate in make full use of the principle of economic rationality of biochemical treatment, several different treatment processes can be unit optimized combination, just rely on a single process is very difficult to meet the requirements of strict water.At present, a lot of treatment methods are applied: biological method + membrane technology treatment, namely "anaerobic + membrane bioreactor + nanofiltration + reverse osmosis + concentrate treatment system".The advantages of using membrane technology are that the effluent water quality is better and the discharge requirements are higher.


The development prospect and direction of waste incineration power generation project

1. Stricter smoke emission standards.As the life of MSW pollution control standard "(GB18485-2014), the full implementation of the household garbage incineration facilities operation and pollution emissions control will be more strict, the new standard of emissions of major pollutants concentration limit has largely with the European Union.Has built incinerators technical renovation to meet the higher emissions requirements, a new incinerators will usually adopt the denitration, dry/half dry acid, activated carbon adsorption removal of dioxins and heavy metals, cloth bag dust remover to remove dust, on the basis of using acid wet process more efficient, advanced SCR catalytic denitration at low temperature and the decomposition of dioxins technology, greatly reduce the main flue gas emissions of pollutants.

2. More significant energy efficiency.In order to greatly reduce the energy consumption of waste incinerators, the efficiency of power generation has been improved.Incinerator flue gas recycling technology, energy saving and discharge of nitrogen oxides, cuts from low temperature catalytic denitration system, in realize high removal of nox and dioxins synchronization at the same time, the high temperature and catalyst to reduce energy consumption by over 50%.At the same time, using intelligent combustion control system, and optimize the furnace and boiler design, improve the steam parameters, using large burning power generation equipment, wind cooling, cooling tower a domestic incinerators usually adopts the forced draft cooling tower of more than 90% lower energy consumption.

3. More effective comprehensive utilization of resources.The development trend of waste incineration is to have more advanced comprehensive utilization of resources, to achieve near zero discharge of sewage and solid waste disposal.The waste water in the factory is recycled after treatment, so as to achieve near zero discharge of waste water.Support a variety of solid waste efficient collaborative treatment, such as the coordinated disposal of medical waste and sludge.New energy-saving materials, environment-friendly materials and recycled materials are preferred in the construction of incineration plants. The slag of incineration plants is used for building materials to realize comprehensive utilization of resources.

4. Development and application of more advanced incineration technology.In order to further reduce the garbage disposal process of the pollutants discharge, race to develop all kinds of garbage disposal in cutting-edge technologies: waste pyrolysis gasification technology, after burning ash melting technology, plasma incineration technology and refuse derived fuel preparation technology, etc.These technologies can further realize the harmlessness and reduction of waste, especially for the treatment of classified waste, and will be the development direction of waste incineration in the future.