Refused Derived Fuels (RDF) and their Energy Recovery

Energy recovery of waste is the most efficient and sustainable solution to take advantage of the energy and raw materials contained in the waste. After having received the treatment waste can be used as fuel in different industries, something that commonly occurs in the cement industry. These extracted fuels through a process of energy recovery are known as Refuse Derived Fuels (RDF).

How Refused Derived Fuels are obtained

The production and processing of Refused Derived Fuels (RDF) for cement kilns, using as raw material non-specific industrial waste, commercial and residential is carried out through a specific processing system in which provide for different conditions for obtaining the RDF applicable to each process.

Refused Derived Fuels (RDF) are fuels prepared from non-hazardous waste for energy recovery by co-processing (RDF’s industrial plants, thermal power plants, cogeneration plants, etc.). After passing through the treatment plants, like the ones we design in SPR Group, these fuels can be used in industrial furnaces for the cement industry, as well as for the steel sector and for the thermal generation of electrical energy in small plants from 25 to 65 Mw incorporating agro-industrial waste.

The importance of the RDFs in the cement industry

The cement manufacturing process requires a very high thermal energy demand, in the order of 700.000 Kcal/Tn. At the same time, solid waste management is an issue which requires constant research into new innovative solutions to find the best available and economically viable options.

Thermal recovery of waste which is not suitable for recovery, recycling or reused is an important option to take into account before sending them to landfills or dumps. For this reason, the use of MSW (Municipal Solid Waste) as well as TDF (Tyre Derived Fuel), has been a growing trend in the industry that has drastically reduced the landfill deposition for the past 10 years.

In cement kilns, this thermal recovery of Refused Derived Fuels is one of the viable models both for the technical and operational conditions (temperatures, consumption capacity, energy demand, etc.), as in the international record, international and local environmental and technical results and locals.

Other uses of RDF in the industry

RDFs are used in a wide variety of industries for the production of electricity or heat to replace traditional fossil fuels. In addition to industrial furnaces of cement or electricity generating plants already mentioned, Refused Derived Fuels are also used in lime kilns, industrial boilers (for example from paper pulp), incinerators with energy recovery or in steel furnaces.

Main features of RDFs

The Refused Derived Fuels from waste have variable characteristics depending on the wastes from and treatment for energy recovery. However, potential consumers RDFs require a fuel with certain properties, as these can influence your production process. The cement plants, in order to know the characteristics of Refused Derived Fuels, perform periodic analyses of them. As noted in this Greenpeace report, the most critical elements to consider in the RDF are:

• Calorific Value (usually expressed in megajoules per kilogram)
• Chlorine content (which usually comes from PVC), determinant in the formation of dioxins and corrosion problems.
• Sulphur content, which causes emissions and also corrosion problems.
• Content of heavy metals, especially mercury, which determines emissions of such metals.
• Ash content, which reduces calorific value and requires further treatment (dumping) except for the cement industry.
• Moisture, which influences the calorific value.
• Biomass content, which determines the emissions that the industries that meet within the emissions trading system can count as zero when considered as neutral.

The role of SPR Group in the RDFs

SPR Group is specialized in the design and execution of treatment plants for the production of Refused Derived Fuels (RDF). At the same time, we optimize and we develop technologies of feeding and dosing of these fuels to the plants of cogeneration, especially in the cement industry.

Although different turnkey treatment plants have been delivered over the years, SPR Group has recently designed a new compact plant model for the Refused Derived Fuels from MSW (municipal solid waste) and TDF (tyres derived fuel). This new design has achieved a great reduction in the investment cost, as well as the operational costs for its installation. The material obtained is a RDF fuel suitable for cogeneration plants. You can consult here the compact plant model for RSF (recovered solid fuels) and plant model compact for TDF (Tyre Derived Fuel).