1、BRITISH STANDARD BS ISO 11520-2:2001 Agricultural grain driers Determination of drying performance Part 2: Additional procedures and crop-specific requirements ICS 65.040.20; NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 11520-2:2001 This British Standard, having been
2、prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 April 2001 BSI 04-2001 ISBN 0 580 37075 5 National foreword This British Standard reproduces verbatim ISO 11520-2:2001 and implements it as the U
3、K national standard. The UK participation in its preparation was entrusted to Technical Committee AGE/23, Equipment for harvesting and conservation, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references Th
4、e British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Stan
5、dard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the re
6、sponsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front
7、cover, the ISO title page, pages ii to v, a blank page, pages 1 to 102, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsReference number ISO 11520-2:2001(E)
8、 INTERNATIONAL STANDARD ISO 11520-2 First edition 2001-02-01 Agricultural grain driers Determination of drying performance Part 2: Additional procedures and crop-specific requirements Schoirs grains agricoles Dtermination des performances de schage Partie 2: Modes opratoires supplmentaires et exigen
9、ces spcifiques la rcolteISO 11520-2:2001(E) ii ISO 11520-2:2001(E)iii Contents Page Foreword.iv Introduction.v 1 Scope 1 2 Normative reference 1 3 Terms and definitions .1 4 Symbols and abbreviated terms 4 5 Test procedure.5 5.1 General5 5.2 Test period5 5.3 Frequency of sampling grain5 5.4 Moisture
10、 removal .6 5.5 Grain dampening .7 5.6 Procedure for a multi-pass test7 6 Grain quality.8 6.1 General8 6.2 Input grain 8 6.3 Output grain .9 7 Methods of correction of test results 10 7.1 General10 7.2 Evaporation rate.10 7.3 Mass flow rate of grain13 7.4 Corrected drying time .13 7.5 Specific therm
11、al energy, total energy and fuel consumption .13 8 Test report 14 Annex A (informative) Grain moisture content and sampling 15 Annex B (informative) Moisture removal in specific crops.19 Annex C (normative) Testing reduction in grain germination20 Annex D (normative) Tables for correction of drier p
12、erformance21 Annex E (informative) Airflow calculations 99 Bibliography102ISO 11520-2:2001(E) iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally car
13、ried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
14、 ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical comm
15、ittees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this part of ISO 11520 may be the subject of patent rights. ISO s
16、hall not be held responsible for identifying any or all such patent rights. International Standard ISO 11520-2 was prepared by Technical Committee ISO/TC 23, Tractors and machinery for agriculture and forestry, Subcommittee SC 7, Equipment for harvesting and conservation. ISO 11520 consists of the f
17、ollowing parts, under the general title Agricultural grain driers Determination of drying performance: Part 1: General Part 2: Additional procedures and crop-specific requirements Annexes C and D form a normative part of this part of ISO 11520. Annexes A, B and E are for information only.ISO 11520-2
18、:2001(E)v Introduction ISO 11520-1 covers only those methods for evaluating the drying performance of continuous-flow and batch grain driers to be used when drying rewetted wheat with a moisture content in the range 20 % to 15 % wet basis. The methods specified in this part of ISO 11520 take account
19、 of the following factors: a greater range in input and output moisture contents; other crops apart from wheat; the impracticality of rewetting (dampening) some grains and of differing thermal characteristics. For correcting the observed evaporation rates to those to be expected at different referen
20、ce ambient and specified grain conditions, the correction formulae given in ISO 11520-1 are augmented by a series of tables from which correction factors are found by interpolation. The methods specified are for determining the water evaporation rate which the machines concerned are able to achieve
21、when drying wheat and other grains under the steady-state conditions prevailing during the tests. Methods for correcting observed performance to other input and reference ambient conditions are also specified.INTERNATIONAL STANDARD ISO 11520-2:2001(E)1 Agricultural grain driers Determination of dryi
22、ng performance Part 2: Additional procedures and crop-specific requirements 1 Scope This part of ISO 11520 specifies additional procedures and gives guidance for testing and evaluating the drying performance of continuous-flow and batch grain driers for specific grain crops including wheat, barley,
23、oats, maize, rice, sorghum and rape. It supplements the general procedures given in ISO 11520-1 based on drying only wheat over the limited range of moisture content of 20 % to 15 % wet basis. Methods and data are given for a) determining the evaporation rate of driers when drying grain crops under
24、steady state conditions, and b) correcting the main drier performance characteristics, including evaporation rate, grain flow rate, drying time and specific energy and fuel consumption, to reference and other ambient conditions. Procedures are specified for sampling input and output grain to assess
25、changes in grain quality. 2 Normative reference The following normative document contains provisions which, through reference in this text, constitute provisions of this part of ISO 11520. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. Howeve
26、r, parties to agreements based on this part of ISO 11520 are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maint
27、ain registers of currently valid International Standards. ISO 11520-1:1997, Agricultural grain driers Determination of drying performance Part 1: General. 3 Terms and definitions For the purposes of this part of ISO 11520, the terms and definitions given in ISO 11520-1 and the following apply. 3.1 r
28、eference ambient conditions ambient conditions of temperature, relative humidity and barometric pressure to which the results of a drier test are to be corrected 3.2 airflow rate volume of air flowing in unit time per unit volume of grain (this value is also the number of air changes per unit of tim
29、e)ISO 11520-2:2001(E) 2 NOTE There are several ways of expressing airflow rate, but for comparison between driers and crops it is convenient to express it in this way. 3.3 drying period period during which drying air passes through grain 3.4 cooling period period during which ambient or near-ambient
30、 air passes through grain 3.5 tempering process by which partially dried grain is held in temporary storage for a number of hours without ventilation, allowing equalization of moisture content within the grain kernel with minimal stress cracking NOTE When drying rice, a common practice is to cool it
31、 to within 2 C of ambient prior to tempering for a minimum of 4 h. One or more further drying, cooling and tempering cycles may be given. 3.6 dryeration process by which hot grain is taken directly from a drier and allowed to temper for a minimum of 4 h before being cooled slowly so as to extract ad
32、ditional moisture without using additional fossil fuel NOTE The hot grain referred to is usually maize or rice, sorghum, soybeans or wheat. 3.7 test period period during which a continuous-flow drier operating at a single steady state for at least one residence time, or a batch drier completing a si
33、ngle full cycle of drying and cooling, is monitored to enable its thermodynamic performance to be assessed NOTE In multi-pass drying there may be several test periods. 3.8 wheat grain of the genus Triticum, of which the commercially important species are T. aestivum (breadwheat), T. durum and T. com
34、pactum (club wheat) 3.9 barley grain of Hordeum sativum or H. vulgare 3.10 oats grain of Avena sativa L. 3.11 naked oats grain of Avena nuda L., which readily loses the husk at threshing NOTE Naked oats have a high protein and oil content and the loss of husk makes the kernels prone to rancidity. 3.
35、12 maize grain of Zea mays L. NOTE This is commonly referred to as corn in North America and some other countries. There are about seven different types of maize distinguished at the “convar” level of classification (between species and cultivar) and within each type there are hybrids having differe
36、nt drying properties. The most widely grown type is the convar indentata commonly known as “dent corn”.ISO 11520-2:2001(E)3 3.13 rice grain of Or yz asa t i vaL . 3.14 paddy rice rough rice rice with the hull or husk still intact 3.15 brown rice rice kernel from which the hull or husk has been remov
37、ed during the milling process 3.16 milled rice white rice white grain or kernel remaining after the removal of the husk or hull and of the bran (whitening); the embryo or germ may be totally or partly removed and part of the bran may still remain on the grain NOTE For some end uses, rice may be drie
38、d in the milled condition. 3.17 head rice for brown and milled rice, either a whole or broken grain with length greater than or equal to three-quarters of the average length of a whole or unbroken grain 3.18 full head rice unbroken head rice 3.19 broken rice either brown or milled rice grain which h
39、as less than three-quarters of the average length of a full head grain 3.20 sorghum grain of Sorghum vulgare Pers NOTE Types of cultivated grain sorghum include kaffir corn, milo and durra (Africa), feteritas (Sudan), shallu, jowar, cholum and “Indian millet” (India), and kaoliang (China). 3.21 rape
40、 (canola) seeds of Brassica napus or B. campestris (also known as B. rapa) NOTE Canola and rapeseed are both members of the same botanical family. The designation “canola” has been established by Canada and is applicable to varieties that meet the canola standard for the level of erucic acid and glu
41、cosinolates in the seed. From the drying performance point of view, there is no evidence of any difference in drying rates or drying characteristics between rapeseed and canola.ISO 11520-2:2001(E) 4 4 Symbols and abbreviated terms These are given in Table 1. Table 1 Symbols and abbreviated terms Sym
42、bol Description Unit B rated output kg/s E water evaporation kg E water evaporation rate kg/s F fuel consumption kg/s G holding capacity of drier kg J specific fuel consumption kg/kg K factor for correcting evaporation (defined in 7.2.3) M moisture content of grain, wet basis (m.c.w.b) % N anticipat
43、ed number of test periods dimensionless Q specific heat consumption J/kg S specific energy consumption J/kg V volumetric capacity of drier m 3 W energy consumption J q v air volume flow rate m 3 /s c 1.3 coefficients in Equation E.1 d 1.3 coefficients in Equation E.2 c pa specific heat of air at con
44、stant pressure kJ kg 1 K 1 c pw specific heat of water vapour at constant pressure kJ kg 1 K 1 d depth of grain bed m f face area at point of air entry to grain bed m 2 h specific enthalpy J/kg i coefficient in Equation E.3 m mass of grain in a single batch or passing through a continuous-flow drier
45、 in a test run kg m mass flow of grain kg/s n exponent in Equation E.3 p pressure or pressure drop Pa s(y) standard error of mean of variable y t duration of test period s density kg/m 3 grain residence time in drier s Other subscripts e electrical f final, at drier exit i initial, at drier inlet o
46、observed value s corrected value at reference or specified conditions p predicted (for model) sys drier system of ducts and plenum chambers t thermal ISO 11520-2:2001(E)5 5 Test procedure 5.1 General This clause shall be used in conjunction with clause 7 of ISO 11520-1:1997. NOTE For the general pri
47、nciple of the tests, test equipment and preparation for testing, see clauses 5, 6 and 7 respectively of ISO 11520-1:1997 Driers are most often used to dry grain which is physiologically ripe and for which the variation in moisture content (m.c.) at harvest is largely a function of ambient weather co
48、nditions. For the purposes of a drier test, such grain can normally be rewetted artificially and the test itself conducted more conveniently outside the harvest period. One advantage of this is that the variation in moisture content of the wet grain is usually very small, i.e. less than 0,5 % wet ba
49、sis (w.b.). This is important for minimizing uncertainty in the results. However, some crops (e.g. maize in France) are harvested at moisture conditions in excess of those to which the grain can reasonably be rewetted and the test has to be conducted during the harvest. In these cases there may be considerable variation in the moisture content of the wet grain and residence times may be large. Clause B.4 of ISO 11520-1:1997 prescribes procedures for estimating the uncertainty (or level of confidence) in derive
