Solution for environmental treatment, ash and slag in coal-fired power plants

By many studies and practical results, it is now possible to confirm that ash and slag of coal-fired power plants are not only a source of hazardous waste, but also a valuable source of raw materials for those Production of building materials. But in order to achieve the set targets on treatment and use of ash and slag, all actors such as state management agencies, owners of coal-fired power plants, and receiving units are required. , using ash, slag ... for synchronous and systematic implementation of related work.

In order to efficiently use agricultural land resources, minimize emissions causing greenhouse effects and environmental pollution, reduce waste treatment costs of industries, save coal fuel, bring efficiency general economy for the whole society, since 2010, the Prime Minister has issued Decision No. 567 / QD-TTg approving the program for development of unburnt building materials until 2020. Subsequently, the Prime Minister Issued Decision No. 1696 / QD-TTg dated September 23, 2014 on a number of solutions to treat ash, slag and gypsum of thermal power plants, chemical fertilizer plants to use as raw materials for production. building materials. Most recently, Decision No. 452 / QD-TTg dated April 12, 2017 approving the Project to accelerate the treatment and use of ash, slag and gypsum of thermal power plants, chemical plants, and fertilizers. building materials production with the target by 2020 is:

1 / To treat and use ash, slag and gypsum to ensure that the amount stored at the storage yard of each thermal power plant, chemical plant or fertilizer plant is less than the total emissions of 2 years of production.

2 / By 2020, treat and use ash, slag, FGD, and PG gypsum as raw materials for production of building materials and use in construction works to reach about 52% of the total accumulated volume (about 75 million tons, including 56 million tons of thermal ash and slag; 2.5 million tons of FGD gypsum; 16.5 million tons of PG plaster).

According to the Vietnam Electricity (EVN) report, in 2017, the total electricity output produced by coal thermal power plants (thermal power plants) was 67.56 billion kWh, accounting for 34.1% of the total output. country. According to the revised Power Plan 7, it is expected that by 2020, the output of coal thermal power plants will account for 42.7% and increase to 49.3% in 2025. Corresponding to that is the amount of ash and slag generated by the The coal power plant is 15 million tons in 2020 and will increase to 20 million tons in 2025.

Being the owner of the most coal-fired power plants in the power system, contributing nearly two-thirds of the total ash and slag volume of coal-fired power plants in Vietnam, so EVN has the role and responsibility to promote the reuse of ash. slag of power plants to achieve the goals set out by the Government.

I. Current status of ash and slag in EVN's coal-fired power plants

1 / Coal consumption and the amount of ash and slag generated:

Currently, EVN owns and operates 12 coal thermal power plants (thermal power plants). In which, there are 10 factories using domestically produced coal from the Vietnam Coal and Mineral Industries Group (TKV) and the Northeastern Corporation. The factories using imported coal are Duyen Hai 3, Vinh Tan 4 and coming here Duyen Hai 3 expanded and Vinh Tan 4 expanded using bituminos coal and sub-bituminous.

The annual average volume of coal used is about 34 million tons, of which domestic coal is 25-27 million tons and imported coal is 9-10 million tons.

The total ash and slag volume of EVN's thermal power plants generated on average in a year is 8.1 million tons.

2 / Management and storage of ash and slag in coal power plants:

Currently, in addition to a part of ash and slag that is received and reused by the units, the remainder of the ash and slag discharged from the units is transported and stored in the slag yards of the thermal power plant. The slag storage is designed to prevent leakage into the environment.

For factories with a unit that collects and processes ash and slag, the ash is taken directly from the silos at the factory, or exploited outside the slag yard and transported by a closed tank truck to ensure that it is not dispersed. dust out to the surroundings. Power plants use both wet and dry slag technologies.

The total volume of ash and slag currently stored in the slag yards of thermal power plants is nearly 15 million tons, of which factories with large volumes of ash and slag are mainly concentrated in Quang Ninh thermal power plants (4.8 million tons), Vinh Tan (3.9 million tons), Duyen Hai (1.8 million tons), Mong Duong 1 (1.7 million tons).

3 / The consumption of ash and slag of the thermal power plant as raw materials for the production of construction materials:

First: About the ash and slag quality of coal thermal power plants:

By many studies and practical results, it is now possible to confirm that the ash and slag of coal thermal power plants are not only a source of hazardous waste, but also a valuable source of raw materials for the production of construction materials.

EVN's thermal power plants have collaborated with independent testing agencies such as VinaControl, the Japan Coal Energy Center (JCOAL) to organize ash sampling and analysis, and through research results of the Institute of Materials. Construction - The Ministry of Construction, thermal power plant ash and slag has the appropriate characteristics for use as raw materials for production of construction materials and for use in construction works.

Second: The consumption of ash and slag in coal thermal power plants:

The ash consumption of the coal plants in the North has been practiced for a long time. Currently, the market for ash and slag in thermal power plants is relatively stable. Most of the factories have found and signed contracts with partners to consume the majority of their ash and slag. Typically, the Pha Lai and Ninh Binh Thermal Power Plants have completely consumed the ash and slag of the plant.

Over the past years, the ash and slag of EVN's coal-fired power plants has been used in the production of construction materials such as concrete, cement, unburnt bricks, construction structures ... Typically, in 2 projects. Son La and Lai Chau hydropower plants have used roller compacted concrete technology, in which the relatively large amount of fly ash is selected from fly ash of Pha Lai thermal power plant.

Particularly in Quang Ninh area, there are Quang Ninh and Mong Duong thermal power plants with 1 volume of ash and slag that has not yet been consumed. Especially Mong Duong 1 Thermal Power Plant, the ash and slag stored in the plant has nearly reached the maximum capacity of the slag disposal site. Therefore, in order to ensure that the plant continues to operate stably, it is urgent to find solutions to consume the amount of ash that continues to arise and the current slag disposal site still exists.

For coal-fired power plants in the South of Duyen Hai and Vinh Tan, the new thermal power plants put into operation in Duyen Hai and Vinh Tan have recently worked with units capable of consuming ash and slag, creating conditions for these units to take samples for experiments in order to make consumption plans. Specifically, at Duyen Hai thermal power station, there is a contract for ash and slag consumption with a total volume of 2.9 million tons / year, equal to 210% of the average annual ash and slag volume of the two factories. Vinh Tan Thermal Power has worked with 9 companies to research and treat ash and slag. However, up to now, the amount of ash and slag consumed is not significant.

II. Solutions to boosting ash and slag consumption of coal thermal power plants

To achieve the goals with ash and slag treatment in power plants, EVN has proposed a number of key solutions to implement the following:

First: Improve the operating efficiency of power plants: This solution is to improve coal-burning efficiency of plants, reduce the amount of ash and slag discharged. EVN has researched and implemented the following contents:

1 / Regularly monitor and calculate the fuel consumption rate of factories, have optimal operating methods for the engine furnaces and generator sets to achieve the highest efficiency.

2 / Adjust the burning mode, regularly monitor the carbon content in the ash to adjust the burning mode accordingly.

3 / Research and develop mixed coal burning solutions, especially for factories using domestic coal, determine the optimal mixing ratio between anthracite coal and bituminous coal / sub-bitumen, in order to select coal types. and the right mixing ratio, improving efficiency and minimizing ash and slag output.

4 / Consolidate, maintain optimum condition and quality of equipment in the production line, ensure equipment is always ready, bringing the highest operating efficiency.

Second: Strengthening the environmental protection: The goal of this solution is to ensure that the power plants comply with the provisions of law, absolutely preventing environmental incidents.

Accordingly, EVN and its affiliates continue to raise awareness about environmental protection. Concentrating all resources to improve environmental protection, especially in coal-fired thermal power plants. On the other hand, manage and transfer ash and slag to transportation partners and handle them according to legal regulations.

Third: Selection of units capable of handling ash and slag: This solution is to find, select and facilitate qualified and capable partners to handle ash and slag in power plants, ensure solving the plant's ash and slag in the long term. The specific contents to be deployed are as follows:

1 / Actively work with interested, capable and committed partners to use a large amount in a long time.

2 / Requiring partners to respond to environmental protection during the process of exploitation, transportation and treatment; Only transfer to partners with sufficient documents proving that the business is capable of transporting, handling and consuming ash and slag.

III. Commitment of EVN to partners to treat ash consumption

In order to promote the reuse of ash and slag, EVN will continue to create maximum conditions for its partners to access to research on the transportation and consumption of ash and slag, specifically:

First: Coordinate with partners to work with state management agencies, propose the promulgation of standards, regulations and guidelines related to ash collection, transportation and reuse.

Second: Create favorable conditions for units that have solutions to reuse ash and slag to produce products to access ash and slag materials in EVN's coal power plants.

Third: Willing to assist partners in finding solutions to ensure the ash and slag quality of thermal power plants; appropriate ground and manpower arrangement within factories to coordinate with units in the installation and operation of ash collection and transportation equipment systems.

Fourth: Prioritize cooperation with partners that have long-term investment targets for ash and slag in large quantities. Consume ash and slag under long-term contracts.

Fifth: Implementing the selection of partners on the basis of competition, openness and transparency.

IV. Conclusions and recommendations

Thermoelectric ash and slag is considered suitable for use as a raw material for construction materials production and for use in construction. Decision No. 1696 / QD-TTg and 452 / QD-TTg are the basis for promoting the treatment and use of thermal ash and slag in Vietnam. To achieve the set goals of treatment and use of ash and slag, it is necessary to involve all actors such as state management agencies, owners of thermal power plants, receiving units and users of ash. ... for a synchronous and systematic implementation of related work. Accordingly, experts, scientists and EVN recommend:

1 / For state management agencies:

Firstly: To propose competent authorities to strengthen propaganda to encourage establishments producing construction materials to use ash, slag and gypsum as raw materials for production, and at the same time promote propaganda to raise awareness of people and businesses on using products from ash, slag to replace construction materials.

Second: Promulgating legal regulations requiring the market for building materials using products made from ash, slag, gypsum, concrete, unburnt bricks ...

Third: Research supporting mechanisms, creating conditions for investors to research and apply, participate in business cooperation with thermal power plants in the treatment and consumption of ash, slag and gypsum.

Fourth: Amending Decree 38/2015 / ND-CP in the direction of viewing thermal ash and slag when meeting technical standards, regulations and technical instructions as raw materials for production of building materials is considered. is a commodity product and is not regulated under the regulations on ordinary industrial waste.

Fifth: Recommend early promulgation of legal documents, standards, technical regulations, technical instructions, economic and technical norms regulating the treatment and use of ash and slag as raw materials. production of construction materials and use in construction works, traffic, leveling ...

2 / For partners transporting and using ash and slag:

First: To carefully study and strictly abide by the State's regulations on environmental protection.

Second: There are plans and plans to receive and consume ash and slag in the long term.

Third: The units cooperate to study the use and exploitation of ash and slag sources of coal thermal power plants to achieve the highest efficiency.

VIETNAM ENERGY SITUATION REVIEW COMMITTEE