1、BS EN 14918:2009ICS 75.160.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDSolid biofuels Determination ofcalorific valueThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 31 March2010 BSI 2010ISBN 978 0 580 6
2、6787 9Amendments/corrigenda issued since publicationDate CommentsBS EN 14918:2009National forewordThis British Standard is the UK implementation of EN 14918:2009. Itsupersedes DD CEN/TS 14918:2005 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PTI/17,
3、Solid biofuels.A list 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 i
4、mmunityfrom legal obligations.BS EN 14918:2009EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14918 December 2009 ICS 75.160.10 Supersedes CEN/TS 14918:2005English Version Solid biofuels - Determination of calorific value Biocombustibles solides - Dtermination du pouvoir calorifique Feste Biobr
5、ennstoffe - Bestimmung des Heizwertes This European Standard was approved by CEN on 10 October 2009. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up
6、-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation u
7、nder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greec
8、e, 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 COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Managemen
9、t Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14918:2009: EBS EN 14918:2009EN 14918:2009 (E) 2 Contents Page Foreword 41 Scope 52 Normative references 53 Terms and definitions .54
10、Principle 65 Reagents .76 Apparatus .87 Preparation of test sample . 118 Calorimetric procedure 129 Calibration . 1810 Gross calorific value 2311 Precision 2712 Calculation of net calorific value at constant pressure 2713 Test report . 28Annex A (normative) Adiabatic bomb calorimeters . 30A.1 Princi
11、ple . 30A.2 Sources of error for the real calorimeter 30A.3 Adiabatic conditions 30A.4 Initial steady state and length of the main period . 31A.5 Correction for drift at the final temperature . 32A.6 Strategy for checking on bias . 32Annex B (normative) Isoperibol and static-jacket bomb calorimeters
12、 34B.1 Principle . 34B.2 Sources of error for the real calorimeter 35B.3 Choice of jacket temperature 36B.4 Rating periods . 36B.5 Calculation of the corrected temperature rise 37Annex C (normative) Automated bomb calorimeters 40C.1 The instrument 40C.2 Calibration . 40C.3 Precision requirements for
13、 calibrations . 41C.4 Comparability of calibration and fuel experiments . 41C.5 Documentation and print-out 42C.6 Precision requirements for fuel experiments 42Annex D (informative) Checklists for the design and procedures of combustion experiments . 43D.1 Introduction . 43D.2 Choice of general para
14、meters . 43D.3 Adiabatic calorimeters . 44D.4 Isoperibol calorimeters 46D.5 Automated bomb calorimeters 47Annex E (informative) Examples to illustrate the main calculations used in this document when an automated bomb calorimeter is used for determinations 48BS EN 14918:2009EN 14918:2009 (E) 3 E.1 G
15、ross calorific value at constant volume . 48E.2 Gross calorific value at constant pressure. 49E.3 Net calorific value 50E.4 Use of typical or default values to calculate calorific values . 51Annex F (informative) List of symbols used in this document . 52Annex G (informative) Key-word index 55Annex
16、H (informative) Default values of most used biofuels for the calculations of calorific values . 59Annex I (informative) Flow chart for a routine calorific value determination 60Bibliography 61BS EN 14918:2009EN 14918:2009 (E) 4 Foreword This document (EN 14918:2009) has been prepared by Technical Co
17、mmittee CEN/TC 335 “Solid biofuels”, the secretariat of which is held by SIS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2010, and conflicting national standards shall be withdrawn at th
18、e latest by June 2010. 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. This document supersedes CEN/TS 14918:2005. WARNING Strict adhe
19、rence to all of the provisions prescribed in this document should ensure against explosive rupture of the bomb, or a blow-out, provided that the bomb is of proper design and construction and in good mechanical condition. According to the CEN/CENELEC Internal Regulations, the national standards organ
20、izations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Ro
21、mania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 14918:2009EN 14918:2009 (E) 5 1 Scope This European Standard specifies a method for the determination of the gross calorific value of a solid biofuel at constant volume and at the reference temperature 25 C in a bomb
22、 calorimeter calibrated by combustion of certified benzoic acid. The result obtained is the gross calorific value of the analysis sample at constant volume with all the water of the combustion products as liquid water. In practice, biofuels are burned at constant (atmospheric) pressure and the water
23、 is either not condensed (removed as vapour with the flue gases) or condensed. Under both conditions, the operative heat of combustion to be used is the net calorific value of the fuel at constant pressure. The net calorific value at constant volume may also be used; formulae are given for calculati
24、ng both values. General principles and procedures for the calibrations and the biofuel experiments are presented in the main text, whereas those pertaining to the use of a particular type of calorimetric instrument are described in Annexes A to C. Annex D contains checklists for performing calibrati
25、on and fuel experiments using specified types of calorimeters. Annex E gives examples to illustrate some of the calculations. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For un
26、dated references, the latest edition of the referenced document (including any amendments) applies. EN 14774-3, Solid biofuels Determination of moisture content Oven dry method Part 3: Moisture in general analysis sample prEN 14778-1, Solid biofuels Methods for sampling prEN 14780, Solid biofuels Me
27、thods for sample preparation prEN 15296, Solid biofuels Calculation of analyses to different bases EN ISO 10304-1, Water quality Determination of dissolved anions by liquid chromatography of ions Part 1: Determination of bromide, chloride, fluoride, nitrate, nitrite, phosphate and sulfate (ISO 10304
28、-1:2007) ISO 651, Solid-stem calorimeter thermometers ISO 652, Enclosed-scale calorimeter thermometers ISO 1770, Solid-stem general purpose thermometers ISO 1771, Enclosed-scale general purpose thermometers 3 Terms and definitions For the purposes of this document, the following terms and definition
29、s apply. 3.1 gross calorific value at constant volume absolute value of the specific energy of combustion, in joules, for unit mass of a solid biofuel burned in oxygen in a calorimetric bomb under the conditions specified BS EN 14918:2009EN 14918:2009 (E) 6 NOTE The products of combustion are assume
30、d to consist of gaseous oxygen, nitrogen, carbon dioxide and sulfur dioxide, of liquid water (in equilibrium with its vapour) saturated with carbon dioxide under the conditions of the bomb reaction, and of solid ash, all at the reference temperature. 3.2 net calorific value at constant volume absolu
31、te value of the specific energy of combustion, in joules, for unit mass of the biofuel burned in oxygen under conditions of constant volume and such that all the water of the reaction products remains as water vapour (in a hypothetical state at 0,1 MPa), the other products being as for the gross cal
32、orific value, all at the reference temperature 3.3 net calorific value at constant pressure absolute value of the specific heat (enthalpy) of combustion, in joules, for unit mass of the biofuel burned in oxygen at constant pressure under such conditions that all the water of the reaction products re
33、mains as water vapour (at 0,1 MPa), the other products being as for the gross calorific value, all at the reference temperature 3.4 reference temperature international reference temperature for thermochemistry of 25 C is adopted as the reference temperature for calorific values NOTE 1 See 8.7. NOTE
34、2 The temperature dependence of the calorific value of biofuels is small (less than 1 J/(g x K). 3.5 effective heat capacity of the calorimeter amount of energy required to cause unit change in temperature of the calorimeter 3.6 corrected temperature rise change in calorimeter temperature caused sol
35、ely by the processes taking place within the combustion bomb. NOTE 1 The corrected temperature rise is the total observed temperature rise corrected for heat exchange, stirring power, etc. (8.6). NOTE 2 The change in temperature may be expressed in terms of other units: resistance of a platinum or t
36、hermistor thermometer, frequency of a quartz crystal resonator, etc., provided that a functional relationship is established between this quantity and a change in temperature. The effective heat capacity of the calorimeter may be expressed in units of energy per such an arbitrary unit. Criteria for
37、the required linearity and closeness in conditions between calibrations and fuel experiments are given in 9.3. A list of the symbols used and their definitions is given in Annex F 4 Principle 4.1 Gross calorific value A weighed portion of the analysis sample of the solid biofuel is burned in high-pr
38、essure oxygen in a bomb calorimeter under specified conditions. The effective heat capacity of the calorimeter is determined in calibration experiments by combustion of certified benzoic acid under similar conditions, accounted for in the certificate. The corrected temperature rise is established fr
39、om observations of temperature before, during and after the combustion reaction takes place. The duration and frequency of the temperature observations depend on the type of calorimeter used. Water is added to the bomb initially to give a saturated vapour phase prior to combustion (see 8.2.1 and 9.2
40、.2), thereby allowing all the water formed, from the hydrogen and moisture in the sample, to be regarded as liquid water. BS EN 14918:2009EN 14918:2009 (E) 7 The gross calorific value is calculated from the corrected temperature rise and the effective heat capacity of the calorimeter, with allowance
41、s made for contributions from ignition energy, combustion of the fuse(s) and for thermal effects from side reactions such as the formation of nitric acid. Furthermore, a correction is applied to account for the difference in energy between the aqueous sulfuric acid formed in the bomb reaction and ga
42、seous sulfur dioxide, i.e. the required reaction product of sulfur in the biofuel. The corresponding energy effect between aqueous and gaseous hydrochloric acid can be neglected due to the usually low chlorine content of most biofuels (induced correction value low). NOTE The typical chlorine content
43、 of wood based solid biofuels is below 0,05 % (m/m), of herbaceous 0,1 % to 1 % (m/m) and of fruit based 0,2 % (m/m) in dry matter. 4.2 Net calorific value The net calorific value at constant volume and the net calorific value at constant pressure of the biofuel are obtained by calculation from the
44、gross calorific value at constant volume determined on the analysis sample. The calculation of the net calorific value at constant volume requires information about the moisture and hydrogen contents of the analysis sample. In principle, the calculation of the net calorific value at constant pressur
45、e also requires information about the oxygen and nitrogen contents of the analysis sample. 5 Reagents 5.1 Oxygen, at a pressure high enough to fill the bomb to 3 MPa, pure with an assay of at least 99,5 % (V/V), and free from combustible matter. NOTE Oxygen made by the electrolytic process may conta
46、in up to 4 % (V/V) of hydrogen. 5.2 Fuse 5.2.1 Ignition wire, of nickel-chromium 0,16 mm to 0,20 mm in diameter, platinum 0,05 mm to 0,10 mm in diameter, or another suitable conducting wire with well-characterized thermal behaviour during combustion. 5.2.2 Cotton fuse, of white cellulose cotton, or
47、equivalent, if required (see 8.2.1). 5.3 Combustion aids of known gross calorific value, composition and purity, like benzoic acid, n-dodecane, paraffin oil, combustion bags or capsules may be used. 5.4 Standard volumetric solutions and indicators, only for use when analysis of final bomb solutions
48、is required. 5.4.1 Barium hydroxide solution, cBa(OH)2 = 0,05 mol/l. 5.4.2 Sodium carbonate solution, c(Na2C03) = 0,05 mol/I. 5.4.3 Sodium hydroxide solution, c(NaOH) = 0,1 mol/I. 5.4.4 Hydrochloric acid solution, c(HCI) = 0,1 mol/I. 5.4.5 Screened methyl orange indicator, 1 g/I solution. Dissolve 0
49、,25 g of methyl orange and 0,15 g of xylene cyanole FF in 50 ml of 95 % (V/V) ethanol and dilute to 250 ml with water. 5.4.6 Phenolphthalein, 10 g/I solution. Dissolve 2,5 g of phenolphthalein in 250 ml of 95 % (V/V) ethanol. BS EN 14918:2009EN 14918:2009 (E) 8 5.5 Benzoic acid, of calorimetric-standard quality, certified by (or with certification unambiguously traceable to)
