The world's largest single sludge incineration project - Dongguan sludge centralized treatment and disposal project

The editor said:

In 2024, the biggest news in sludge field should be Suez won the bid for the world's largest single sludge incineration project so far 。 It has been more than two months since the bid was won, but it has not caused any waves in the industry. I think it is necessary to write something.

The world's largest single sludge incineration project—— Dongguan Sludge Centralized Treatment and Disposal Project The total scale of the project is 5400 tons/day, and the scale of Phase I is 4000 tons/day, based on the water content of 80%.

This project becomes domestic The first sludge incineration power generation project (No other combustibles are mixed), and photovoltaic power generation is equipped to maximize energy output.

The flue gas treatment is equipped with NOx ultra clean emission measures, and the heavy metal Hg ultra clean emission treatment unit is reserved The first project in China that can reach the strictest American latest sludge incineration flue gas emission standard (The most stringent flue gas emission standard in sludge incineration worldwide).

Ultra high standard wastewater treatment system makes it It is the first waste water zero discharge project in the sludge field in China.

The centralized sludge treatment and disposal project in Dongguan covers an area of about 132.95 mu, with a sludge treatment capacity of 2700 tons/day (water content of 60%). It adopts the process of "bubbling fluidized bed incineration+waste heat recovery and utilization+flue gas treatment", supporting wastewater treatment, deodorization, afterheat power generation, photovoltaic power generation and other projects.

With a total investment of 2.188 billion yuan, the project was started in March this year and is expected to be completed and put into operation in 2026.

Project scale: short-term sludge treatment scale is 2000t/d (based on 60% water content), and land for long-term sludge treatment scale of 700t/d (based on 60% water content) is reserved.

Designer ： China Municipal Engineering Southwest Design and Research Institute Co., Ltd

Sludge incineration : Suez Environmental Technology (Beijing) Co., Ltd

The sludge comes from more than 50 municipal sewage plants in Dongguan. After being treated by the sewage plant, the sludge has a moisture content of about 60% and is transported to the sludge incineration plant for incineration.

For the sludge from more than 50 sewage plants involved in recent years, the weighted average value of sludge moisture content varies in different seasons. After 2021, the weighted average water content of sludge from the sewage plant will be stable between 50% and 55%, and the weighted dry basis low calorific value will also have an overall upward trend.

See the figure below for the weighted dry basis net calorific value?

As for the final disposal of sludge, some experts have summarized it very well, "either go to heaven or go to the ground".

An important factor restricting the land use of sludge is the pollution of heavy metals and persistent organic compounds. Therefore, when sludge is used for land use, it is necessary to ensure that the content of heavy metals and persistent organic substances does not exceed the standard. During the application process, the amount of sludge should also be controlled to avoid the accumulation of heavy metals and persistent organic substances.

Dongguan does not realize the separate source treatment of industrial sewage and domestic sewage, which also restricts the land use of sludge.

The disposal method with incineration as the core is the most thorough sludge disposal method. Sludge incineration can destroy all organic matter, kill pathogens and minimize sludge volume. The incinerated ash can be used for phosphorus recovery, which is conducive to resource recovery and utilization.

Steam generated during sludge incineration, Rich It can be used for power generation and resource utilization. At the same time, by strengthening the flue gas purification measures, the emission can reach the standard, and the slag generated after incineration can be used as building materials.

In general, sludge incineration is a reliable disposal path for large cities with large and concentrated sludge production.

As mentioned in previous articles, fluidized bed incinerator is the most suitable type for sludge incineration（ What type of furnace is most suitable for sludge incineration ）Bubble fluidized bed and circulating fluidized bed, as representatives of fluidized bed incinerators, are also different.

Compared with circulating fluidized bed, bubbling fluidized bed has the following advantages:

1. The low fluidization speed of bubbling bed makes the flue gas wear less on the heat transfer surface and requires less energy consumption.

2. The bubbling bed does not need to be equipped with separators, return devices and other corresponding facilities, and has simple structure, low investment and convenient maintenance.

3. The ash particles after sludge incineration are small. The use of general coal-fired circulating fluidized bed separation device may lead to the phenomenon of less return material collection and blocked circulation, so it is necessary to design and use more efficient separation device and return material device.

(Thermolis bubble fluidized bed incinerator in Suez)

For sludge, bubbling fluidized bed is a more suitable sludge incineration equipment. According to statistics, the vast majority of foreign sludge incineration projects use bubbling fluidized bed incinerators for incineration. There are many engineering examples of sludge incineration with such incinerators in China. The bubbling fluidized bed incinerator finally adopted in this project uses the Thermolis 2R incineration technology of Suez.

at present The most stringent flue gas emission standard for domestic sludge incineration projects is the Shanghai local standard Emission Standard of Air Pollutants for Domestic Waste Incineration (DB31/768-2013).

The implementation standard of incinerator flue gas emission of this project is proposed to refer to Shanghai local standard Emission Standard of Air Pollutants for Domestic Waste Incineration DB31/768-2013).

On the basis of the current commonly used flue gas treatment process in domestic sludge plants, the project strengthens the high emission standard requirements for the project's deacidification, denitrification and mercury removal, and the treatment process of "SNCR (in furnace)+electrostatic precipitation+dry reactor+powdered activated carbon jet+bag filter+wet deacidification+fixed mercury adsorption (reserved)+external SCR". This makes the project a domestic sludge incineration field, The first project that can achieve super net emissions of NOx and Hg.

At present, the denitrification process of domestic sludge incineration projects is mainly combustion control method, which can meet the requirements of flue gas emission. If the NOx emission standard is further improved in the future, it may not be able to ensure that the flue gas meets the standard stably only by using the ordinary combustion control method and SNCR method. Therefore, this project will increase SCR at the tail end to ensure that the NOx emission concentration meets the standard stably and set SCR bypass system, which can be exceeded in the near future.

After incineration, most of the heavy metals are enriched in the fly ash in the form of oxides and removed with the removal of particles, such as Mn, Ti, etc., which can be effectively removed in cloth bags without special consideration. The form of Hg is relatively complex, and its boiling point is lower than that of other heavy metals. Therefore, some of Hg exists in the solid phase and some exists in the gas phase, and it is relatively difficult to remove. Hg in the solid phase can be removed along with the removal of particles. Hg in the gas phase is divided into ionic mercury and elemental mercury. The former is soluble in water and can be removed in a wet scrubber, while the latter can be removed using activated carbon or mercury adsorber. The most stringent global control of Hg is the flue gas standard for sludge incineration in the United States.

Heavy metals in this project are controlled by "powder activated carbon injection before bag type dust collector"+ Reserved mercury adsorber ”In the double insurance scheme, the heavy metals in the flue gas are mainly absorbed by activated carbon, intercepted by cloth bags and discharged in the form of fly ash. The overall removal efficiency is not less than 85%. The remaining heavy metals are transferred to the waste water through wet washing to ensure that the flue gas meets the emission standards.

Mercury adsorber. I should be impressed after reading the previous articles. There is an adsorption device called SPC（ Is it true that mercury in sludge incineration projects in the United States is not up to standard?   ）It can further adsorb the heavy metal mercury, and the mercury emission value can meet the emission limit of the industry's most stringent United States sludge incineration emission standard. The limit removal of mercury in the sludge incineration field in the United States is mostly treated by SPC adsorption devices.

The incineration of sludge in this project will produce high temperature flue gas of about 850 ℃. The waste heat carried by high-temperature flue gas can be recycled in subsequent equipment, and the recycling process is divided into two steps. The first step is to heat the fluidized air through the high-temperature air preheater, and the heat energy in the flue gas is sent back to the incinerator for recycling through the heated fluidized air. The second step is to let the flue gas from the high-temperature air preheater enter the waste heat boiler for heat recovery after utilization, which is used to recover the sensible heat of flue gas, and produce superheated steam for power generation, urea pyrolysis, SCR temperature rise and other systems.

The main utilization mode of steam in this project is power generation According to the sludge analysis of the project and considering the steam production range of the waste heat boiler, two sets of pure condensing steam turbines with installed power of 6.0MW are considered to be selected as the power generation equipment. During the power generation process, some saturated steam can also be extracted from the steam turbine as other heat sources.

The annual power generation of waste heat recovery is nearly 60 million kW · h.

The project adopts the design scheme of block power generation and block grid connection, and the installed photovoltaic capacity is 2680kWp. The average annual power generation is 2.64 million kWh based on the 25 year calculation and the attenuation of the photovoltaic system power generation.

Write at the end:

In addition to the above, Dongguan sludge incineration project, as the largest sludge incineration project in the world, has also fully considered the functions, intelligent management BIM design and a series of the latest technologies and means in the industry, fully combining the project characteristics and regional characteristics, create a world-class sludge treatment project, and explore a comprehensive sludge treatment project integrating low-carbon, smart, ultra clean emissions, energy recovery, resource recovery and science popularization.

(Effect picture)

The park landscape space fully combines the sponge city, rainwater garden and reclaimed water reuse after sludge treatment to create a waterscape, demonstrating the environmental protection and energy saving level and sustainable concept of the sludge plant. At the same time, combining with the architectural style, extract the cultural elements of the plant to create unique cultural symbols, and build the plant into an additional science popularization and display function besides the production function.