The Refuse Derived Fuel Process

by Haahner Bruck


Posted on 04-03-2023 02:16 AM



The Refuse Derived Fuel Process is a waste-to-energy process that diverts municipal solid waste from landfills and generates a revenue stream for waste processors. It also helps reduce greenhouse gas emissions.

The process involves several stages of waste processing before the combustible fraction is shaped into pellets and sold as fuel. Depending on the fuel requirements, additional processing equipment is used.

Primary Separation

The Refuse Derived Fuel Process is an alternative way to dispose of solid waste. This process converts municipal waste into a combustible material called RDF, which can be used for energy generation and as a source of recyclable materials.

RDF can be manufactured from a variety of materials, including municipal solid waste (MSW), industrial waste and commercial waste. The waste is sorted into high calorific fractions that can be burned in cement kilns as alternative fuels.

Primary separation is one of the major steps involved in the production of RDF from MSW. It involves separating the waste into Bio-degradable, Glass, Rags, Paper, Plastic, Leather and Rubber, Metals and other domestic hazardous and Inert particles.

It also includes a number of preliminary processes such as size screening, shredding and pelletizing. These processes convert the larger particles of waste into smaller ones for easier handling and transportation. They can be done by a machine, such as a flail mill, a hammermill or a shredder.

Size Screening

The size screening process separates combustible materials into a fuel fraction that is suitable for combustion. This separation process enables the Refuse Derived Fuel Process to divert waste from landfills and convert it into a valuable fuel source.

Screening efficiency depends on the size of the screen hole and the loading. It is very important to select a suitable screen size for the application in order to achieve optimal performance.

Empirical formulas are used to determine the screening capacity in sizes below 0.25 mm (fine screening). However, as particle size decreases, these formulas become increasingly unreliable.

There are various factors that can affect the efficiency of a screen including the amount of loading, the material volume, and the mesh size. This can also be affected by the type of material being screened and its characteristics such as density, moisture, and hardness.

Shredding

The Refuse Derived Fuel Process utilizes mechanical methods to shred incoming MSW, separate out non-combustible materials, and produce a combustible mixture that is suitable as a fuel in a dedicated furnace or a supplemental fuel in a conventional boiler system.

Refuse derived fuel (RDF) is an important alternative energy resource. It can be made from a wide variety of general waste and municipal solid waste.

During the RDF process, these wastes are broken down into smaller pieces and separated from non-combustible materials such as metals and glass. This helps to reduce greenhouse gas emissions and conserve landfill space.

Often, RDF is processed to a finer size before it can be used as a fuel in facilities such as cement kilns or RDF power plants. The finer the waste, the higher the calorific value and the lower the moisture content.

Pelletizing

The Refuse Derived Fuel Process pelletizes municipal solid waste, or MSW, before burning it in a combustion furnace. This reduces waste volume and produces more consistent heat and moisture content.

Pelletizing systems typically utilize a disc or rotary drum to pelletize fines and binder into spherical pellets. As material moves through the disc, loose pendular, funicular and capillary bonds are replaced by a dense solids-air-water bond that causes densification and coalescence.

This type of pelletizing system has several advantages over strand pelletizers, including lower cost, more uniform pellet size and a more compact footprint. In addition, it is much less sensitive to process variations such as melt temperature and pressure and is able to handle a wider range of polymers.

Another benefit of UWPs is that all cooling water is transported to and from the cutting chamber by means of pipes, eliminating the need for unnecessary water troughs and slides. This also helps prevent dust and fines from building up in the cutting chamber, which can disrupt the pelletizing process.

Summary

The RDF process is a waste-to-energy process that diverts municipal solid waste from landfills while also generating revenue for waste processors.

Several stages of waste processing are involved in this process before the combustible fraction is formed into pellets and sold as fuel.

RDF contributes to the reduction of greenhouse gas emissions and is a viable alternative to traditional fossil fuels.

Conclusion

The RDF process is a promising solution to the growing challenges of waste management and energy production. RDF not only helps reduce greenhouse gas emissions by diverting municipal solid waste from landfills and converting it into fuel, but it also generates revenue for waste processors. It has been around for decades and has proven to be an efficient waste-to-energy process. RDF has the potential to become a significant contributor to the renewable energy sector, given the growing demand for sustainable energy and waste reduction.


What are RDF and SRF?

What are RDF and SRF?

by RDF'er


Posted on 28-01-2023 05:12 PM



If you are looking for a waste disposal solution, or a cheap fuel you may be asking yourself, "What are RDF (Refuse Derived Fuel) and SRF (Solid Recovered Fuel)?". These are two types of waste derived fuel (WDF) that are used in various ways, but in almost all applications you won't want to use them.

Theoretically you can use them to power your home or business, as a source of energy, or as a substitute for natural gas. But, RDF is still considered waste for the purposes of the law (unless the stringent End of Waste Criteria can be met), and users of the fuel are required to comply with the IED, which has superseded the WID.

End of Waste Criteria (EoW) defines the point at which certain wastes stop being considered waste and acquire the status of a product (or a secondary raw material).

RDF Remains a Waste and it's Use as a Fuel is Strictly Controlled

According to Article 6(1) and (2) of the Waste Framework Directive 2008/98/EC, certain specified waste ceases to be waste once it has undergone a recovery (including recycling) operation and satisfies certain requirements to be defined in accordance with certain legislative circumstances. Only the more rigorously processed SRF can meet the requirements and then only in specific circumstances.

SRF May Comply with End of Waste Criteria  but Rarely

Although Solid Recovered Fuel (SRF) is a form of Waste Derived Fuel, it differs from Refuse Derived Fuel (RDF) in that it is far better as a fuel. It is primarily utilised in operations like cement kilns and new-generation ATT plants that call for materials with a high level of purity, tiny particle size, high calorific value, and low moisture content.

The creation of pellets from SRF for use in industrial operations is being pursued in the UK.

According to data for cement kilns in the UK, a quantity of this WDF of about 400,000 tonnes of SRF was used in 2019 and 2020.

International technical specifications, which define, among other factors, the chemical and physical parameters of an SRF, apply to solid recovered fuels. However, SRF continues to be a waste for legal purposes (unless strict End of Waste Criteria can be met), and consumers of the fuel must adhere to the IED, which has replaced the WID.

Businesses that are able to use RDF and SRF are rare. All normal commercial operations can dismiss the possibility that either fuel can be used as a cheap fuel. The fact that these fuels are classed as wastes means that any user would have to comply with waste management regulations and hold a waste disposal permit.

The charges made by the environmental regulator to police the licence the user must hold would negate any cost reduction from the price of the fuel, let alone the costs of complying with the stringent emissions requirements.

Refuse derived fuel

A Refuse Derived Fuel and SRF are two types of low cost fuels, but they are not clean. They cannot be used as a renewable energy source for all but a very few industries. In effect only the cement industry uses significant amounts apart from municpal incineration plants.

Don't be blinded by the fact that RDF and SRF are recycled and reused when used as a fuel. Nor do they have environmental and economic advantages when the cost of the burden of waste regulation is considered.

However, there are some differences between the two which are worth knowing.

Refuse derived fuel is produced from municipal solid waste and can be used for electricity and heat production. It is also used for power plants and incineration facilities. The quality of the fuel depends on the requirements of the client.

SRF usually made fom Municipal Solid Waste (MSW), but also in industries such as motor vehicle recyclers, can in rare circumstances be a viable alternative for reducing carbon emissions. It can also be used by companies keen to improve their sustainability credentials for helping to preserve the earth's natural resources. SRF production is a more complex process than used for RDF and requires higher levels of technology.

Most SRF is produced from non-hazardous municipal and commercial waste. In addition, it is typically more refined than RDF. For example, it can have a much lower chlorine content.

Several European countries are using this kind of fuel under stringent regulation. These include Germany, the Netherlands, and Austria.

Solid recovered fuel

Solid recovered fuel is usually produced from non-recyclable waste, such as paper, food and household waste, green waste, sewage sludge, and plastic bottles.

As an alternative energy source, SRF can be used for many purposes. Some of the common uses include district heating systems, electricity production, and industrial processes.

However, it is important to understand the properties of SRF to make use of it. To do so, thermogravimetric analysis is required. For example, it enables us to identify the combustion characteristics of SRF.

Thermogravimetric analysis requires precise sampling and measurement. Often, this is done with a small sample. We also need to be careful to avoid oxidative atmospheres during measurements.

In addition to measuring the calorific value of the material, we can also measure its mercury content.

Moreover, we can examine the reaction functions. Choosing the appropriate reaction function is important in order to increase the fitness of the kinetic model.

Common uses for RDF and SRF

RDF and SRF are terms used to describe processed waste. They may be made from a variety of industrial and commercial waste, including plastic-paper fluff, labels, corrugative materials and more. Each product has different uses.

The first step in RDF/SRF production is to collect the solid waste. Waste can come from several sources, including municipal and commercial, construction and demolition, and special waste. These can be sorted to remove recyclables, and then processed.

An RDF plant will make a lower grade fuel, while an SRF plant will produce a higher grade fuel.

RDF/SRF can be burned to produce electricity or gas in very specifically design and controlled boilers/ incinerators. It has a high calorfic value, and can be transported easily.

However, its financial advantage even when cobusted in bulk may be questionable. A number of factors determine whether a facility will use RDF or SRF, including waste taxes, fuel quality, and transport costs.