TABLE OF CONTENTS



Annex 9.2

General requirements and specifications for

Waste Derivate Fuel

TABLE OF CONTENTS

1. Introduction 1

2. Classification 3

3. COMPLIANCE RULES FOR CLASSIFICATION 4

4. COMPLIANCE RULES FOR SPECIFICATION 4

5. POTENTIAL UTILIZATION OF RDF 5

1. Introduction

Mechanical Biological Treatment output fractions intended as secondary fuels fall into the category of Waste Derivative Fuels, also referred to as solid waste fuels, secondary fuels, substitute fuels or alternative fuels. In the absence of a legal definition or universally accepted term, the two most established terms relevant to thermally recoverable waste fractions are RDF and SRF. Conventionally RDF refers to a combustible high CV waste fraction (e.g. paper, card, wood and plastic) produced by the mechanical treatment of municipal or similar commercial/industrial waste.

A technical committee of the European Committee for Standardization (CEN/TC 343) works to unify the various approaches to WFD, providing quality management guidance.

RDF or SRF may originate from sources other than MBT, such as source segregated paper/card/plastic fractions. The following figure shows the relationship between different terminologies.

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Figure 1: Venn diagram exemplifying terminology used for thermally recoverable waste fractions in mechanical-biological treatment plants (MBT) and their quality assurance/quality control

MBT processes may be designed and optimized for the production of one or more primary outputs:

• Biostabilized output, to be disposed of in landfill

• WDFs, such as RDF or SRF

• Biogas, for energy and heat production and

• CLO for application on land

The following figure provides a schematic for different flow sheet approaches to MBT plants.

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Figure 2: Simplified schematic of potential flow sheet options for mechanical-biological treatment plants

Waste derived fuels generally refer to the production of refuse derived fuels (RDF) and solid recovered fuels (SRF). The terms RDF and SRF are often used interchangeably but there is a significant difference between RDF and SRF which determines its ultimate destination. The preparation of RDF requires a basic level of treatment to remove recyclates from predominantly an MSW waste stream, while SRF requires a higher standard of preparation to produce a fuel. RDF is typically destined for standard Energy from Waste (EfW) facilities which also accept unprepared mixed waste streams. SRF on the other hand are solid fuels prepared from non-hazardous waste and are typically utilised for energy recovery in incineration or co-incineration plants (within cement kilns, power stations, etc.) as an alternative to fossil fuels also meeting the classification and specification requirements laid down in the CEN15359 European standard.

The development in the production and therefore also use of waste fuels is driven by several factors, these mainly being summarised as:

← the EU Landfill Directive 1999/31/EC, which requires diversion of biodegradable waste from landfill. This led several states to implement a complete ban for organic waste in landfill,

← the Waste Incineration Directive 2000/76/EC as now superseded by 2010/75/EC,

← the Renewable Energy Sources (RES) Directive 2001/77/EC,

← the Emission Trading Directive 2003/87/EC,

← rising energy costs and the consequent interest to substitute expensive primary fuels, and

← the development of European Standards (eg CEN15359).

RDF and SRF can be used in a variety of ways to produce electricity, heat or a combination of both. It is often used alone or together (as a partial substitute) with traditional sources of fuel in the following industries:

← power plants for energy generation

← industrial power plants

← cement kilns

← incineration plants (R1 –status)

← pyrolysis plants

← steel mills, etc.

The main outlets of RDF/SRF are currently found in the cement industry as well as paper manufacturing. The European countries where RDF/SRF production is already well established are Germany but also Austria, Finland, Italy, the Netherlands, and Sweden. Countries where RDF/SRF production and energy recovery is currently being developed are Belgium, the United Kingdom and ever more increasingly the eastern European countries for example Slovenia, Serbia, and now Croatia. In various countries several waste derived fuels are produced as different forms of appearance (fluff, pellets, chips, powder).

It must be noted that quality management for RDF/SRF plays a key role in efforts to establish viable market outlets, not least by creating confidence in suppliers, end-users, and regulators. However, standardization in isolation cannot guarantee increased market share. The European market for SRF/RDF is developing and remains unpredictable. The RDF/SRF contaminant properties and combustion behavior critically affect its potential applications. Problems with low-quality RDF characteristics, particularly high chlorine and trace metals content, have led to a decline in co-combustion applications.

Not all kinds of RDF/SRF are suited for all types of installations. The classes have determined as a tool for identifying and pre-selecting SRF. However, the performances of the plant where SRF is used are depending on the properties of the SRF and more significantly on the design and operating condition of such a plant.

2. Classification

The classification system for SRF is based on limit values for three important fuel characteristics.

These are:

a) the mean value for net calorific value (ar);

b) the mean value for chlorine content (d);

c) the median and so" percentile values for mercury content (ar).

Each characteristic is divided into 5 classes. The SRF shall be assigned a class number from 1 to 5 for each characteristic. A combination of the class numbers makes up the class code.

The classification system for SRF, based on the EN 15359:2011 is presented at the following table:

Figure 3: Classification system for SRF

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3. COMPLIANCE RULES FOR CLASSIFICATION

For a considered 12 months period, for each characteristic specified in the classification system, the compliance of a particular SRF shall be established by demonstration that the measured properties conform to the limit values defined for that class. This shall be performed at a period in which a quality management system (QMS) is applied. The maximum weight of a lot for classification shall be no more than 1,500 tonnes. When the 12 month production is less than 15,000 tonnes the lot size for classification shall be one tenth of the amount produced in a 12 months rolling period.

If there are significant changes in the properties of input materials or in the production process conditions , the production shall be considered to be interrupted. Significant here means such a change that would result in a change of class code.

For each lot, at least one measurement of each characteristic shall be performed. An additional laboratory sample shall be taken in case of a cross check is needed. The laboratory sample shall be kept for a period of minimum 12 months. The sampling and sample procedure are illustrated in the following figure. For sampling and sample reduction EN 15442 shall be applied.

If, at the end of the 12 month period, an incomplete data set exists (With less than 10 data), these data shall be used in the following 12 month period and be completed with the consecutive measurements of that period to a full data set of 10 measurements. In the case that for one characteristic to be classified several analyses of a 12 month period lead to different classification results, always the highest class has to be used for the determination of the class of the SRF.

After the start of the production of SRF or after a significant change, the minimum of 10 measurement results can be obtained on one or several lots as defined above. When several combined samples are taken on the same lot they shall be taken independently.

4. COMPLIANCE RULES FOR SPECIFICATION

The SRF specification to be agreed upon by the supplier and the user may define the lot size up to a maximum of 1 500 tonnes as well as by the compliance rules. In case these elements are not defined in the SRF specification, then the lot size and compliance rules specified for the classification apply.

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Figure 4: Illustration of sampling and sample procedure. Number and size of increments depend on the heterogeneity of the SRF and on required accuracy and precision (source BS EN 15359:2011)

5. POTENTIAL UTILIZATION OF RDF

The produced RDF for the Mechanical treatment can be treated using advanced thermal treatment facilities like pyrolysis or gasification. The treatment of produced RDF does not included in the scope of the present study, however in the following paragraphs a brief description of the advanced thermal treatment facilities and especially pyrolysis is presented.

As the populations grow and countries become more developed, there is a continuously growing need for new and sustainable sources in the world. There is also an increased demand for renewable sources of energy, resulting in increased interests in the processing of municipal solid waste (MSW) as an energy resource both by biochemical and thermo-chemical means. Among the thermo-chemical technologies for MSW conversion, pyrolysis is the most versatile in relation to the flexibility of obtaining primary products. The application of pyrolysis technology to MSW is quite promising as the energy content of the MSW can be extracted in the form of primary pyrolysis products including gas, liquid and solid product. Due to the fact that MSW feedstock presents heterogeneity, RDF feedstock is a better feedstock for thermal conversion like pyrolysis. RDF has a more uniform composition, relatively constant density and size, easier transport logistics and higher heating value in comparison with raw MSW.

The following diagram describes the generic process flows for pyrolysis and gasification.

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Figure 5: Advance Thermal Treatment Technologies generic process flows

Thermal treatment reactor

Pyrolysis process will produce syngas and solid residue. The composition of the syngas and solid residue will depend on the process conditions employed, which include operating temperature, oxygen level, heating rate and residence time in the reactor. The main types of thermal treatment units available, their application and operating conditions are summarized in the following table.

Table 1: Thermal treatment reactors regarding pyrolysis

|Reactor |Typical application |Operating conditions |

|Rotating Kiln |Pyrolysis |Typical operate at low temperatures of around 400-600°C. The unit can |

| | |accommodate large size feed material (200 mm). The kiln is heated |

| | |externally and waste is fed in from one end of the kiln which slowly |

| | |rotates creating a tumbling action. This mixes the waste and ensures |

| | |contact with the heating surface and gases inside the kiln. |

|Heated tube |Pyrolysis |The tubes are heated externally and temperatures as high as 800°C are used.|

| | |The process can accommodate large size feed material. The waste passes |

| | |through the tube at a set speed to ensure the pyrolysis process is |

| | |complete. |

|Surface contact |Pyrolysis |Small size feed material required and temperatures as high as 800°C are |

| | |used. The process operates at high temperatures and the small size of the |

| | |feed gives high heating rates. The application of this technology is to |

| | |maximize the rate of pyrolysis. |

Source: Advanced thermal treatment, Defra

Gas and Residue Treatment Stages

Solids will inevitably be discharged from the process. These solids include metals together with carbon. In the case of pyrolysis the level of carbon is significant. Larger particles of solids in the thermal treatment reactor are usually discharged as bottom ash and slag. Lighter ash is usually collected when the gas is separated with the use of cyclones and ultimately filters. In addition, volatile metals such as lead, tin, cadmium and mercury will be carried in the gas until such point that the gas is cooled for them to be sufficiently condensed. Pollution control strategies will typically be on a smaller scale than for incineration technologies, hence less costly, due to the reduction in the volume of process air required.

Energy Recovery/Utilisation of Syngas

One of the potential benefits of pyrolysis is that the syngas can be used in a number of different ways:

• In energy production by burning the syngas in a boiler to generate steam.

• As a fuel in gas engine.

• As a chemical feedstock

• As a potential source of hydrogen, which have applications in both power generation and as vehicle fuel.

The following table summarizes the key outputs from Advanced Thermal Treatment Processes.

Table 2: Examples of outputs from Pyrolysis process

|Outputs |State |Potential Markets |

|Flue gas treatment residue |Solid, powder/sludge. Invariably a |Specialist Disposal or treatment potential use in |

| |hazardous waste |Chemical treatment works |

|Syngas |Gaseous |Heat or power generation/fuel/some chemical |

| | |application |

|Condensate |Liquid |Fuel/chemical application. Care needs to be taken |

| | |with the chemical composition of this and the hazards|

| | |associated with it |

|Pyrolysis Char |Solid |Hazardous waste but could be used as coal replacement|

| | |in certain combustion applications |

Hofstetter Pyrolysis Plant, Switzerland Herne (D) Germany

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Figure 6: Pyrolysis plants

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