1、BRITISH STANDARD BS845-2:1987 Methods for Assessing thermal performance of boilers for steam, hot water and high temperature heat transfer fluids Part 2: Comprehensive procedure UDC 621.18.018BS845-2:1987 This British Standard, having been prepared under the directionof the Refrigeration,Heating and
2、 AirConditioning Standards Committee, was published underthe authority of the BoardofBSI and comes into effecton 30 June1987 BSI 11-1999 First published as BS845 April1939 First revision as BS845 September1961 Second revision as BS845 July1972 Third revision as BS845-2 June1987 The following BSI ref
3、erences relate to the work on this standard: Committee reference RHE/10 Draft for comment83/73795DC ISBN 0 580 15857 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Refrigeration, Heating and Air Conditioning Standards Committee (RHE/-
4、) to Technical Committee RHE/10, upon which the following bodies were represented: Associated Offices Technical Committee Association of British Solid Fuel Appliances Manufacturers Association of Shell Boilermakers Boiler and Radiator Manufacturers Association Ltd. British Coal British Combustion Eq
5、uipment Manufacturers Association British Foundry Association British Gas plc Building Services Research and Information Association Chartered Institution of Building Services Engineers Department of Energy (Energy Efficiency Office) Department of Energy (Gas Standards) Department of the Environment
6、 (Property Services Agency) Domestic Solid Fuel Appliances Approval Scheme Engineering Equipment and Materials Users Association Health and Safety Executive Hevac Association Institute of Domestic Heating Engineers Society of British Gas Industries The following bodies were also represented in the d
7、rafting of the standard, through sub-committees and panels: Association of Consulting Engineers British Paper and Board Industry Federation (PIF) Institution of Chemical Engineers Institution of Mechanical Engineers National Industrial Fuel Efficiency Service Water-tube Boilermakers Association Amen
8、dments issued since publication Amd. No. Date of issue CommentsBS845-2:1987 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Test preparation 2 4 Minimum test duration 3 5 Test operation 3 6 Instrumentation 4 7 Measurement procedure 5 8 Ca
9、lculations 10 9 Report 16 Appendix A Report data 22 Appendix B Calculation of production rate of unweighed ash 37 Appendix C Radiation, convection and conduction losses for boilers of conventional design 37 Appendix D Guiding principles 38 Appendix E Selection of assessment procedure 40 Figure 1 Dia
10、gram of heat flows in and out of the unit 42 Figure 2 Boundary points of unit 43 Table 1 Minimum duration of tests 3 Table 2 Measurement tolerances 6 Table 3 Symbols and units 17 Table 4 Typical radiation, convection and conduction losses from water-tube and shell boilers 38 Table 5 Typical radiatio
11、n, convection and conduction losses from sectional hot water boilers 38 Publications referred to Inside back coverBS845-2:1987 ii BSI 11-1999 Foreword This Part of BS845 has been prepared under the direction of the Refrigeration, Heating and Air Conditioning Standards Committee. Together with BS845-
12、1 it supersedes BS845:1972 which is withdrawn. The revised edition of BS845 describes, in two Parts, the procedures that should be used and the data that should be collected in order to obtain an assessment of the thermal performance of steam, hot water or high temperature heat transfer fluid boiler
13、s, generally of output greater than44kW. The test results may be based on either the net or the gross calorific value of the fuel. The tests described in this British Standard are for thermal performance only but are based on the assumption that boilers are operated during the tests in such a manner
14、 as to comply with relevant safety requirements and the requirements of national environmental legislation. BS845 is published in two separate Parts as follows: Part 1: provides a concise but complete procedure and is convenient for boilers which are thermodynamically simple, i.e.having a single maj
15、or source of heat input and a simple water or steam or high temperature heat transfer fluid; Part 2: provides a comprehensive procedure suitable for all boilers, including those with multiple thermal flows to and from the boiler. Part 2 is intended for testing boiler plant of any size burning any of
16、 the fuels available to commerce and industry. It may be used for contractual tests or for any subsequent test at full or part output and is suitable for testing all types of boiler including waste heat and electric boilers. Allowance is made for the use of fluidized bed combustion and for the use o
17、f domestic refuse as fuel. A British Standard 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. Summary of pag
18、es This document comprises a front cover, an inside front cover, pagesi andii, pages1 to44, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS8
19、45-2:1987 BSI 11-1999 1 1 Scope This Part of BS845 describes a comprehensive procedure for conducting thermal performance tests on steam, hot water or high temperature heat transfer fluid boilers to give results within a tolerance of2percentage points 1)and for presenting the results in tabular form
20、. This Part makes use of both the direct and the indirect methods of test. Test results are based on either the gross or the net calorific value of the fuel. This comprehensive procedure is suitable for all boilers, including those with multiple thermal flows to and from the boiler. NOTEThe titles o
21、f the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS845 the following definitions apply. 2.1 unit a steam, hot water or high temperature heat transfer fluid boiler, generally of output greater than44kW, including firin
22、g equipment, together with ancillary plant or equipment, such as superheater, economizer, air heater, fans and pumps lying within the unit boundary (as indicated in Figure 1 and Figure 2) 2.2 solid fuel any fuel in the solid state, including wastes with declared characteristics 2.3 liquid fuel petro
23、leum fuel oils in accordance with BS2869 or any other fuel in the liquid state with declared characteristics 2.4 gaseous fuel manufactured gas (first family), natural gas (second family) or LPG, i.e.propane or butane, (third family) or any other gaseous fuel with declared characteristics 2.5 gross c
24、alorific value the amount of heat liberated by the complete combustion, under specified conditions, of unit volume of a gas or unit mass of a solid or liquid fuel in the determination of which the water produced by combustion of the fuel is assumed to be completely condensed and its latent and sensi
25、ble heat made available (see7.8, clause8 and BS526) 2.6 net calorific value the amount of heat generated by the complete combustion, under specified conditions, of unit volume of a gas or unit mass of a solid or liquid fuel in the determination of which the water produced by the combustion of the fu
26、el is assumed to remain as a vapour (see7.8, clause8 and BS526) 2.7 heat input the heat value of the fuel fired during the test based upon the net or gross calorific value (to be stated), plus the sensible heat in the fuel above the air intake temperature and any heat supplied to the unit from a sep
27、arate source. In the case of waste heat and electric boilers the reference to net or gross calorific value does not apply 2.8 heat output the heat value of the steam or hot water supplied by the unit less the heat value of any water or steam returned to the unit during the test 1) One percentage poi
28、nt is one hundredth of the total amount concerned, in this instance, the heat input.BS845-2:1987 2 BSI 11-1999 2.9 radiation, convection and conduction losses the losses from water, steam, combustion air, or gas backed surfaces prior to the flue gas temperature measurement point and directly from fl
29、ame to the floor and surroundings of the unit 2.10 thermal efficiency the heat output divided by the heat input expressed as a percentage 2.11 direct procedure the determination of thermal performance from thermal input and output, based on measurement. Further measurements are taken to determine th
30、e heat losses, although one or more minor losses may be determined by difference in the heat balance 2.12 indirect procedure the determination of thermal performance by the assessment of the thermal losses and the measured thermal input or output. Major thermal losses are determined directly from me
31、asured quantities; minor losses are determined directly, or assessed, and in the case of radiation and convection lossesAppendix C gives values 3 Test preparation 3.1 Before a test, the unit shall be examined for condition and cleanliness (see clause9). NOTE 1It is important that the unit is in a su
32、itable condition for testing and in particular that it is in an acceptable state of cleanliness. NOTE 2Appendix D gives information concerning guiding principles for the carrying out of tests andAppendix E deals with the selection of the test method. 3.2 The unit shall be isolated from any supplies
33、of feed water or fuel other than those passing through their respective measuring devices. Precautions shall be taken to avoid all leakages of water or steam, inwards or outwards, which will affect the results of the test. Similar precautions shall be taken with liquid or gaseous fuel. Wherever prac
34、ticable unused pipes shall be blanked off or be subject to continuous supervision. 3.3 The unit shall be observed in operation for as long as may be necessary to confirm whether or not each of the following working conditions can be met. a) Output of hot water or steam from main boiler stop valve or
35、 flow connection. b) Pressure and temperature of steam or water at the unit outlet. c) Pressure and temperature of feed or return water entering the unit. d) Temperature of air at entry to the unit. e) Temperature and analysis of the flue gases. It shall also be verified that the characteristics of
36、the fuel to be burned are within the agreed range (seeD.8) and that the fuel can be burned at the necessary rate (seeD.7). NOTEIf such preliminary observation discloses that the required working conditions, as listed in3.3 a) toe), cannot be met in any one or all particulars, or if the characteristi
37、cs of the available fuel are different from those specified, the test may be carried out, by agreement between the parties concerned, under the working conditions shown to be feasible, and on agreement also on the resultant changes in the guarantee values. 3.4 Where circumstances require correction
38、curves to be applied for deviations from the reference temperature of feed water temperature, temperature of steam or water and external air, as well as for deviations of steam or water throughput and fuel analysis, the method of application shall be stated. The correction shall be made to bring the
39、 makers guarantee values to the “as tested” conditions. NOTEThe use of correction curves should be agreed between the parties concerned prior to the commencement of the test. 3.5 Boiler water shall comply with BS2486. 3.6 In preparation for the test the unit shall be run for a sufficient time to att
40、ain equilibrium of temperature and combustion at test load conditions (see3.7). NOTEAt this time it is also necessary to ensure that national legislation (e.g.Health and Safety at Work etc. Act1974 and Clean Air Acts) is being complied with.BS845-2:1987 BSI 11-1999 3 3.7 Before the test the followin
41、g conditions shall prevail: a) the heat output shall not vary by more than5% from the value required; b) the extreme values of steam pressure shall not differ from one another by more than 6%; c) The extreme values of difference between the temperatures of the flue gas at the unit exit and the ambie
42、nt air shall not differ from one another by more than6%. That is t 7 t 3will not vary by more than6%. 3.8 During the whole of the preliminary running the unit shall be fired with the fuel(s) that will be used for the duration of the test. 4 Minimum test duration Having attained the steady conditions
43、 given in clause3, a one hour control period shall be followed by the minimum test periods given in Table 1. NOTEThe control period may be counted as part of the test period only by mutual agreement between the parties concerned. Following the test a further control period may be maintained. Table 1
44、 Minimum duration of tests 5 Test operation 5.1 Operation of equipment during test 5.1.1 During the test, the cleaning equipment shall not be operated unless there is a specific operational need to do so. If the cleaning equipment is to be operated during the test this shall be recorded in the repor
45、t see clause9 andAppendix Ac)viii) together with the time(s) and period(s) of such operation(s). NOTEThe need to operate the cleaning equipment should be agreed between the parties concerned prior to the test. 5.1.2 During the test, the boiler shall not be blown down nor shall the timed or continuou
46、s integral ash-quenching equipment be operated unless such operations are normal functions or there is a specific operational need to do so. In the event of blow down or operation of the ash-quenching equipment during the test, allowance shall be made for the operations in the heat account (see7.6).
47、 NOTEThe need to blow down or operate the ash-quenching equipment should be agreed between the parties concerned. 5.2 Rejection of test runs The test shall be discontinued or rejected if excessive variations occur such as to disturb the running equilibrium (see3.7). NOTEMomentary variations may occu
48、r without involving the rejection of the test, providing that, taking into account the frequency, duration and time of occurrence of the variations, the parties agree that the variations are not such as to upset appreciably the equilibrium of temperature in the different parts of the unit. Direct te
49、sts, and indirect tests with fuel measured Solid fuel equipment giving steady burning rates Solid fuel equipment giving possible cyclic variations in the mass of fuel present (e.g.underfeed, gravity feed stokers, hand de-ashed units) a Solid fuel equipment burning domestic refuse, bagasse, and other solid fuels of variable calorific value Liquid and gaseous fuels (including waste heat boilers) Electric boilers 4h Not less than8h and at least one full cycle of firing or de-ashing operations, beginning and ending at the same points on the cycle 6h 2h 1
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