1、PD CEN/TR15716:2008ICS 75.160.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWPUBLISHED DOCUMENTSolid recovered fuels Determination ofcombustion behaviourThis Published Documentwas published underthe authority of theStandards Policy andStrategy Committee on 30September 2008 B
2、SI 2008ISBN 978 0 580 59374 1Amendments/corrigenda issued since publicationDate CommentsPD CEN/TR 15716:2008National forewordThis Published Document is the UK implementation of CEN/TR15716:2008.The UK participation in its preparation was entrusted to TechnicalCommittee PTI/17, Solid biofuels.A list
3、of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obli
4、gations.PD CEN/TR 15716:2008TECHNICAL REPORTRAPPORT TECHNIQUETECHNISCHER BERICHTCEN/TR 15716June 2008ICS 75.160.10English VersionSolid recovered fuels - Determination of combustion behaviourCombustibles solides de rcupration - Dtermination ducomportement de la combustionFeste Sekundrbrennstoffe - Be
5、stimmung desVerbrennungsverhaltensThis 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, G
6、reece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement
7、 Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TR 15716:2008: EPD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 2 Contents Page Foreword3 Introduction .4 1 Scope 7 2 Combustion of solid fu
8、els.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 numbers10 2.5 Combustion prediction tool10 3 Thermal gravimetric analysis .13 4 Standard fuel analysis.17 4.1 Genera
9、l17 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 chara
10、cterisation.19 5.1 General19 5.2 Determination of fuel composition 21 5.3 Composition and calorific value of the volatile matter22 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 veloc
11、ity 33 5.8 Slagging and fouling behaviour.34 6 Operational behaviour in the combustion process35 7 Summary.38 Bibliography 40 PD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 3 Foreword This document (CEN/TR 15716:2008) has been prepared by Technical Committee CEN/TC 343 “Solid recovered fuels”, the secret
12、ariat 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. PD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 4 Introductio
13、n 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
14、 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
15、 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 i
16、n 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 mos
17、t 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
18、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 categoris
19、ed 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 Materi
20、als (ASTM) and the German Institute for Standardization (DIN Deutsches Institut fr 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-hous
21、e, 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 PD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 5 SRF
22、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, thi
23、s 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.
24、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 outline
25、d 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 po
26、wer 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 th
27、e 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;
28、 and lastly emissions and residues. The systematic evaluation of these additional topics requires area specific analyses, tests, and measurements. PD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 6 Concerning combustion behaviour, the standard analysis of the SRF will determine the basic parameters about t
29、he 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 advanc
30、ed 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
31、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
32、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
33、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 reliabl
34、e 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 fue
35、l 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 th
36、e 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;
37、 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 c
38、onverge. PD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 7 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
39、 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
40、 both from theoretical and practical perspectives. The former can define combustion as the rapid chemical reaction of oxygen with the combustible elements of a fuel. While the later where the engineer is concerned with boiler design and performance might define combustion as the chemical union of fu
41、el combustibles and the oxygen of the air, controlled at a rate that produces useful heat energy. The two definitions implicitly consider many key factors. For complete combustion within a furnace, four basic criteria shall be satisfied: 1) adequate quantity of air (oxygen) supplied to the fuel; 2)
42、oxygen and fuel thoroughly mixed (turbulence); 3) fuel-air mixture maintained at or above the ignition temperature; 4) furnace volume large enough to give the mixture time for complete combustion. Quantities of combustible constituents within the fuel vary by types. Figure 3 shows the significant ch
43、ange in the combustion air requirements for various fuels, resulting from changes in fuel composition. It illustrates the minimum combustion air theoretically required to support complete combustion. Key Y Stochiometric air demand in nominal cubic meter dry air per kilogram fuel Figure 3 Stoichiomet
44、ric air to fuel ratio for some SRFs PD CEN/TR 15716:2008CEN/TR 15716:2008 (E) 8 In an ideal situation, the combustion process would occur with the stoichiometric quantities of oxygen and a combustible based on underlying chemical principles. However, since complete mixing of air and fuel within the
45、furnace is virtually impossible, excess air shall be supplied to the combustion process to ensure complete combustion. The amount of excess air that should be provided varies with the fuel, boiler load, and type of firing system, and it is in the range of 0,1 0,6 or even more. Solid fuel combustion
46、consists of three relatively distinct but overlapping phases: heating phase (time to ignition); gas phase combustion (time of gas phase burning); char combustion (time for char burnout). Firstly, the time to ignition involves particle heat up due to radiation and convection in the furnace driving of
47、f moisture and volatiles adsorbed in the solid. Solid fuels, especially fresh biomass, can release combustible volatiles below 100C and ignition can occur as soon as the particle is not completely surrounded by water vapour. The time to ignition is relatively short. For plastics it is different, the
48、y do not contain volatiles in the traditional meaning. They are often transparent so they heat up slowly and then start melting. Film plastics tend to shrink and form molten droplets. At about 400C de-polymerization starts (pyrolysis) where gaseous combustible compounds release. The time to ignition
49、 is long compared to regular fuels of the same particle size. Secondly, the time of gas phase burning involves the volatiles released through desorption and pyrolysis burn in a flame around the particle until a solid char is left. This phase is long for plastics compared to coal because plastics (except PVC) do not form a char at all. The flaming particle can fly as a warm air balloon. Thirdly, the time for char burnout is a gas/solid reaction which for coal is the longest step and it is strongly dependent on particle size and porosity et
