CEN/TR 15716:2008

SLOVENSKI STANDARD
01-september-2008
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Solid recovered fuels - Determination of combustion behaviour
Feste Sekundärbrennstoffe - Bestimmung des Verbrennungsverhaltens
Combustibles solides de récupération - Détermination du comportement de la
combustion
Ta slovenski standard je istoveten z: CEN/TR 15716:2008
ICS:
75.160.10 Trda goriva Solid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 15716
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
June 2008
ICS 75.160.10
English Version
Solid recovered fuels - Determination of combustion behaviour
Combustibles solides de récupération - Détermination du Feste Sekundärbrennstoffe - Bestimmung des
comportement de la combustion Verbrennungsverhaltens
This Technical Report was approved by CEN on 21 January 2008. It has been drawn up by the Technical Committee CEN/TC 343.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15716:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3
Introduction .4
1 Scope .7
2 Combustion of solid fuels.7
2.1 Basis of solid fuel combustion.7
2.2 Basics of some common combustion systems that utilises SRF .8
2.3 Determination of characteristic parameters .9
2.4 Use of classification numbers.10
2.5 Combustion prediction tool.10
3 Thermal gravimetric analysis .13
4 Standard fuel analysis.17
4.1 General.17
4.2 Proximate analysis: Moisture, volatiles, and ash content.17
4.3 Ultimate analysis: C, H, N, S, Halogens.17
4.4 Gross calorific value (GCV)/net calorific value (NCV).18
4.5 Particle size distribution .18
4.6 Ash content and ash melting behaviour .19
5 Advanced laboratory methods for fuel characterisation.19
5.1 General.19
5.2 Determination of fuel composition .21
5.3 Composition and calorific value of the volatile matter.22
5.4 Kinetic properties .25
5.5 Image analysis method for particle size distribution.30
5.6 Apparent densities of particles and intermediates .32
5.7 Aerodynamic lift velocity .33
5.8 Slagging and fouling behaviour.34
6 Operational behaviour in the combustion process.35
7 Summary.38
Bibliography .40

Foreword
This document (CEN/TR 15716:2008) has been prepared by Technical Committee CEN/TC 343 “Solid
recovered fuels”, the secretariat of which is held by SFS.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
Introduction
Historically, SRF goes back to the oil crises approximately 30 years ago, when refused derived fuel (RDF)
was promoted as a substitute low cost fuel. Contrary to that situation, the producers of SRF took the initiative
for the implementation of a quality system to meet and guarantee specified fuel classification and specification
parameters. Quality systems to check their production now exist in several EU member states and efforts are
being made by CEN/TC 343 to develop European Standards for SRF [1].
The production and thermal utilisation (energy recovery) of Solid Recovered Fuels (SRF) from bio wastes,
residues, mixed- and mono waste streams have significant relevance as a key component of an integrated
waste management concept.
The implementation of SRF production in an integrated waste management concept demands a potential
market for these products. Known proven markets are found in the European energy sector and in other more
product-oriented sectors like cement or lime industry by substitution of fossil fuels. The capacities for co-
utilisation of these products, to include utilisation in minor thermal shares, are enormous, especially in the new
European member states as most of the energy production of these countries relies on fossil fuels.
A successful application of solid recovered fuel in power plants and industrial furnaces would require a
thorough understanding of the fuel properties which include the combustion behaviour, emission potential,
impact on facility etc. The determination of combustion behaviour which is the main focus of this document
seeks to outline possible methods and procedures that can be adopted to analyse any given solid recovered
fuel. An approach has therefore been outlined where the determination of combustion behaviour is
categorised into four groups which combine to give a holistic impression of the combustion progress of SRF in
both mono and co-firing systems (see Figure 1).

Figure 1 — Scheme to determine combustion behaviour of SRF
While there are standardised methods, such as from the American Society for Testing and Materials (ASTM)
and the German Institute for Standardization (DIN Deutsches Institut für Normung e. V.), for determining
combustion behaviour for primary fuels (e.g. coal), the process is not the same for SRF. At present, there are
no standardised methods for SRF. Most of the available methods are in-house, usually designed for particular
types of SRF, e.g. waste, or bio-residue fractions to suit a specific combustion system like grate firing,
fluidised bed, pulverised fuel system, and cement kiln. Figure 2 gives an overview about the broad variety of
SRF utilisation routes using an example of co-combustion in power plants and industrial furnaces.
Co-combustion also includes indirect co-firing systems such as gasification (Lahti, Zeltweg) and pyrolysis
(ConTherm). While the environmental aspect of the thermal utilisation of SRF is very important, this report
focuses only on the combustion aspect.

Figure 2 — SRF utilisation routes
Solid recovered fuel can be made of any combustible non-hazardous waste and processed to a quality that
allows to classify it in accordance with CEN/TS 15359 and which fulfils specifications as agreed with the
customer. Considering this, the main problem becomes obvious: How to define reliable methods to describe
the combustion behaviour of solid fuels such as SRF, valid for all possible types of input material and
combustion systems? A systematic approach adopted herein to determine combustion behaviour is outlined in
Figure 1. It is grouped into four categories:
 standard fuel analysis;
 laboratory-scale tests with advanced methods;
 semi-technical and pilot-scale combustion tests;
 full-scale test.
In general, such a four-step procedure is an effective way to successfully integrate a new fuel in an existing
power plant or an industrial furnace. In any case, full scale tests are the most reliable but very expensive with
several bottlenecks (e.g. retrofits, permits, time, etc.) and that is the reason for the need to develop and
standardise methods which are reliable, fast, and not expensive according to the various firing systems are
essential. Besides the evaluation of parameters concerning combustion behaviour, the steps before full scale
implementation also forms substantial basis to reliably evaluate other areas of major interest such as grinding
and fuel feeding; slagging, fouling and corrosion; and lastly emissions and residues. The systematic
evaluation of these additional topics requires area specific analyses, tests, and measurements.
Concerning combustion behaviour, the standard analysis of the SRF will determine the basic parameters
about the combustible and incombustible matter. The amount of energy, the contents of water, volatiles, fixed-
carbon, ash, and particle size will roughly dictate the type of the combustion system that is best suited. In
addition to the standard analysis, a selected combustion system might require an advanced parameter
analysis, if possible, with a close relation to case specific process parameters. Such a correlation will
substantially enhance the reliability of transfer studies. An example, in the case of a pulverised firing system,
is the maximum particle size required for a complete combustion in order to avoid fuel plummeting into the
bottom ash.
Currently, the activities towards the combustion behaviour of SRF rely largely on standard analysis and
laboratory-scale tests, which were originally developed with certain limitations and applicable to solid fuels
such as lignite and hard coal. A common problem of these methods is that parameters related to SRF during
combustion are not sufficiently covered. These methods make sure consistent quality of the SRF supply rather
than to predict combustion performance. Therefore, the development of the so-called advanced test methods
to fill the gap and amending existing test apparatus and measurement conditions is required.
The driving force to introduce SRF rests much on economic factors. In most cases, the end user will be either
the operator of a power plant or an industrial furnace. The primary focus will be an unrestricted and reliable
operation of the facility. One wants to assess the possible risks and dangers. In case of retrofits, the end user
needs to calculate the required cost on modifications and operation. It can be assumed that due to possible
operational risks such as corrosion, the plant operators will select the fuel with the most appropriate qualities.
Such requirements are needed tools to control the quality of the SRF and to deliver them according to
specification. As such, the knowledge of the combustion behaviour is an essential aspect for the
commercialisation of SRF. It will allow the optimisation of the process and the assessment of possible risks
and dangers prior to full-scale application.
Some methods and parameters will be introduced in the subsequent sections, but whatever methods are to be
used in the future should be orientated towards the following aspects:
 reproducibility;
 repeatability;
 reliability;
 time efforts (rapid test methods);
 cost effectiveness;
 possibilities for automatic testing.
The authors summarise and refer to past and current activities trying to describe combustion behaviour of
SRF. The idea is to identify a common and successful practice where various approaches converge.
1 Scope
This Technical Report gives a review on determination methods for exploring how different SRFs behave in
different combustion systems, e.g. with respect to time for ignition, time for gas phase burning and time for
char burn out, including information on technical aspects like slagging and fouling, corrosion as well as
required flue gas cleaning for meeting the emission limit values induced by the Waste Incineration
Directive (WID).
2 Combustion of solid fuels
2.1 Basis of solid fuel combustion
Combustion of fuels shall be considered both from theoretical and practical perspectives. The former can
def
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