CEN TR 16911-2015 Heat meters - Recommendations for circulation water in industrial and district heating systems and their operation.pdf

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1、BSI Standards PublicationHeat meters Recommendations for circulation water in industrial and district heating systems and their operationPD CEN/TR 16911:2015National forewordThis Published Document is the UK implementation of CEN/TR 16911:2015. The UK participation in its preparation was entrusted b

2、y Technical Committee CPI/30, Measurement of fluid flow in closed conduits, to Subcommittee CPI/30/7, Volume flow-rate methods.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 provisions of

3、a contract. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 90922 1ICS 91.140.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This Published Document was published under

4、the authority of theStandards Policy and Strategy Committee on 31 January 2016.Amendments/corrigenda issued since publication Date Text affectedPUBLISHED DOCUMENTPD CEN/TR 16911:2015TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 16911 December 2015 ICS 91.140.10 English Version Heat m

5、eters - Recommendations for circulation water in industrial and district heating systems and their operationThis Technical Report was approved by CEN on 16 November 2015. It has been drawn up by the Technical Committee CEN/TC 176. CEN members are the national standards bodies of Austria, Belgium, Bu

6、lgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

7、Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Member

8、s. Ref. No. CEN/TR 16911:2015 EPD CEN/TR 16911:2015CEN/TR 16911:2015 (E) 2 Contents PageEuropean foreword . 4 Introduction 5 1 Scope 6 2 Normative references 6 3 Terms and definitions . 6 3.1 General 6 3.2 Types of water 8 3.3 Units . 9 3.3.1 General 9 3.3.2 Measurands . 9 4 Symbols and abbreviation

9、s . 9 4.1 Chemical terms 9 4.2 Technical terms 10 5 Water quality . 10 5.1 General . 10 5.2 Effects of the water constituents 11 5.2.1 Gases . 11 5.2.2 Water-insoluble substances . 12 5.2.3 Water-soluble substances . 12 5.2.4 Oils/greases . 13 6 Systems engineering . 13 6.1 Systems conception . 13 6

10、.1.1 General . 13 6.1.2 Materials 13 6.1.3 Pressure maintenance and water supply 14 6.2 Water treatment techniques 15 6.2.1 General . 15 6.2.2 Filtering . 16 6.2.3 Demineralization . 16 6.2.4 Softening 16 6.2.5 Degassing 16 6.2.6 Catalytic and electrochemical oxygen scavenging . 16 7 Production tech

11、nology . 17 7.1 Standard values for the circulation water 17 7.2 Low-salt operation . 18 7.3 Salty operation 18 7.4 Technical aspects related to the operation 19 7.4.1 General . 19 7.4.2 Filling and supplementary water . 19 7.4.3 Underpressure 20 7.4.4 Exceptional operating conditions 21 7.4.5 Direc

12、t heating 21 7.4.6 Indirect heating 21 7.4.7 Partial evaporation . 21 PD CEN/TR 16911:2015CEN/TR 16911:2015 (E) 3 7.5 Conditioning . 22 7.5.1 General . 22 7.5.2 pH value increase . 22 7.5.3 Hardness stabilizing 23 7.5.4 Oxygen scavenging . 23 7.5.5 Corrosion inhibitors 24 7.5.6 Water tracing dyes fo

13、r the circulation water . 25 7.5.7 Antifreezing agents 25 7.6 Monitoring . 25 7.6.1 General . 25 7.6.2 Assessment criteria 25 7.6.3 Measurement frequency 27 7.6.4 Dosing of conditioning agents 28 7.6.5 Sampling 29 7.6.6 Measurement procedures . 31 8 Hygienic, toxicological and environmental aspects

14、. 31 8.1 General . 31 8.2 Hygienic and toxicological aspects . 31 8.3 Environmental aspects . 32 Bibliography . 33 PD CEN/TR 16911:2015CEN/TR 16911:2015 (E) 4 European foreword This document (CEN/TR 16911:2015) has been prepared by Technical Committee CEN/TC 176 “Heat meters”, the secretariat of whi

15、ch is held by SIS. 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 16911:2015CEN/TR 16911:2015 (E) 5 Introduction This docum

16、ent is based on the German Guideline AGFW FW 510 prepared by the German Heat and Power Association (AGFW) that represents the state of the art but does not have a normative status has been reproduced in this Technical Report with the permission of AGFW. This Technical Report is an informative docume

17、nt that describes a process that may be applied for the operation of district heating facilities and gives recommendations for the water used in such facilities. The water quality described in this Technical Report can be used also during testing of heat meters. PD CEN/TR 16911:2015CEN/TR 16911:2015

18、 (E) 6 1 Scope This Technical Report applies to industrial and district heating supply by means of high-temperature water heating facilities (flow temperature 100 C). This also applies to high-temperature water heating facilities (flow temperature 100 C) that are directly connected to district heati

19、ng networks. In this Technical Report, the aforementioned supply variants will, in the following, be referred to as “district heating facilities”. This document applies without limitations to new facilities. For existing district heating facilities, the application of this Technical Report is recomm

20、ended in order to prevent faults due to the chemical composition of the circulation water that would affect the facilities safe operability and availability. NOTE Informative notes in the form of guidance and recommendations are identified correspondingly and set in italics for better differentiatio

21、n. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any am

22、endments) applies. EN 1717, Protection against pollution of potable water in water installations and general requirements of devices to prevent pollution by backflow ISO 11466, Soil quality Extraction of trace elements soluble in aqua regia 3 Terms and definitions For the purposes of this document,

23、the following terms and definitions apply. 3.1 General 3.1.1 district heating heat (regardless of its origin) which is supplied by means of a transfer medium (mostly hot water or steam) commercially on the basis of a supply agreement and from the delivery of which no collateral duties arise with reg

24、ard to leasing regulations 3.1.2 hot-/warm-water heating plants hot-/warm-water generating facility in connection with a district heating network 3.1.3 water treatment measures taken to remove solid particles, water-soluble substances (salts) and gases from the filling-, supplementary- or circulatio

25、n water 3.1.4 primary network district heating network in indirect (e. g. heat exchanger) or direct connection with the heat generator 3.1.5 secondary network district heating network separated from the primary district heating network by a substation with different system parameters PD CEN/TR 16911

26、:2015CEN/TR 16911:2015 (E) 7 3.1.6 tertiary network end-users domestic installation 3.1.7 heat exchanger with intermediary medium heat exchanger with a safety system for the indirect heating of drinking water and in which the heating side and the drinking water side are separated by two walls; the s

27、pace between the two walls is filled with a medium 3.1.8 chalk/carbonic acid equilibrium if calciferous water is heated up, the concentration of bonded calcium hydrogen carbonate decreases with increasing temperature, and the so called “chalk/carbonic acid equilibrium” shifts from the side of the ca

28、lcium hydrogen carbonate through the escaping carbon dioxide towards the side of the calcium carbonate: + +32 3 2 2Ca (HCO ) CaCO CO H O3.1.9 bicarbonate decomposition after sofenting and in cause of higher temperature, sodium bicarbonate gradually decomposes into at least sodium hydroxid, water and

29、 carbon dioxide (at about 55C, higher pressure) 2 NaHCO3 Na2CO3+ CO2 + H2O Na2CO3+ 2H2O 2 NaOH + H2CO3H2CO3 CO2 + H2O 3.1.10 boiler scale conglomerate of low-solubility alkaline earth salts which form at temperatures 7. 3.3.2.3 electrical conductivity the salt concentration is generally determined b

30、y measuring the electrical conductivity which includes all dissociated elements of the investigated medium, i.e. bases, acids and salts. In water chemistry, the reference temperature used to measure electrical conductivity is 25 C, the unit of measurement is S/cm 3.3.2.4 sum of alkaline earth (hardn

31、ess) the former term “hardness” has been replaced by the term “sum of alkaline earth“ Note 1 to entry: The former units for the alkaline earth concentration (d and mval/l) have been replaced by mmol/l, mol/m3and mg/l. The following applies to the conversion of the units: 1 mmol/l = 1 mol/m3 correspo

32、nding to 2 mval/l that will give 56 mg CaO/l Note 2 to entry: Example of calculation for the conversion of the former units: 3,4 mval/l: 2 = 1,7 mmol/l Note 3 to entry: Contrary to the concentration indications derived from the term “hardness” (dH), technical expressions such as “water softening” an

33、d “softened water” remain in usage. 4 Symbols and abbreviations 4.1 Chemical terms Al3+aluminium ion Ca2+calcium ion CaCO3 calcium carbonate CaSiO3 calcium silicate CaSO4 calcium sulphate Clchloride ion CO2carbon dioxide PD CEN/TR 16911:2015CEN/TR 16911:2015 (E) 10 Cu+ / Cu2+copper(I) ion / copper(I

34、I) ion EDTA ethylenediaminetetraacetic acid or ethylenediaminetetraacetate Fe iron Fe 2+ / Fe 3+ iron(II) ion / iron(III) ion KS4.3 acid capacity up to pH value 4,3 KS8.2 acid capacity up to pH value 8,2 Mg2+magnesium ion MgCO3 magnesium carbonate N2nitrogen NaCl sodium chloride (common salt) NaHCO3

35、 sodium hydrogen carbonate NaOH sodium hydroxide (caustic soda) Na3PO4 trisodium phosphate Na2SO3 sodium sulphite Na2SO4 sodium sulphate NTA nitrilotriacetic acid O2oxygen PO43- orthophosphate ion S2- sulphide ion SO32- sulphite ion SO42- sulphate ion Zn2+zinc ion 4.2 Technical terms EV expansion ve

36、ssel DEV diaphragm expansion vessel MIF magnetic inductive flow measurement DFR differential pressure regulator DOC dissolved organic carbon TOC total organic carbon 5 Water quality 5.1 General Untreated water may contain insoluble and, especially, soluble substances as well as gases. Insoluble subs

37、tances are frequent in surface water, infrequent in groundwater, whereas water from public supply networks only contains traces of them. Soluble substances occur in untreated water in the form of inorganic salts (especially calcium-, magnesium- and sodium salts) and organic substances. The soluble g

38、ases are mostly oxygen, nitrogen from the air, and carbon dioxide. PD CEN/TR 16911:2015CEN/TR 16911:2015 (E) 11 In district heating facilities, these water constituents can lead to malfunctions and either have to be removed, or their effects to be limited. The use of insufficiently treated filling o

39、r supplementary water or the inflow of water and/or air into district heating facilities from the outside can lead to system malfunctions due to deposits and corrosion. When assessing the cost-effectiveness of protective measures to prevent the diverse types of damages, the fact that damage may, und

40、er certain circumstances, lead to considerable costs that cannot be calculated in advance has to be taken into account. When complying with the standard values, the alkalinization of the water on metallic surfaces furthers the formation of homogeneous oxidic covering layers which are highly resistan

41、t against corrosion. A prerequisite is, however, that the filling and supplementary water be treated correctly. In district heating facilities, one fundamentally differentiates between low-salt and salty operation, depending on the quality of the circulation water. Further plant-specific prescriptio

42、ns and guidance can be found in the Technical Connection Conditions (TCC). 5.2 Effects of the water constituents 5.2.1 Gases 5.2.1.1 General Gases enter the circulation water due to the following processes: utilization of non-degassed filling and supplementary water; air leakage into the system in t

43、he event of underpressure (e.g. insufficient pressure maintenance); air inclusion during the initial, partial or new filling of the system; external water inflow; diffusion through permeable components (e.g. diaphragms, plastic pipes, seals). 5.2.1.2 Oxygen Oxygen (O2) causes unalloyed and low-alloy

44、 ferrous materials to corrode. Oxygen inflow therefore has to be prevented as far as this is technically justifiable. Damage directly due to corrosion can manifest in the form of perforations in heat generators, pipes and radiators made of unalloyed or low-alloy ferrous materials. The blinding of si

45、eves, measuring equipment and filters due to corrosion products is considered as an indirect consequence of corrosion. 5.2.1.3 Nitrogen Nitrogen (N2) is an inert gas and, as a water constituent, only causes problems when its concentration is so high that free nitrogen fractions (gas bubbles) form in

46、side the system. Gas bubbles may occur, since the solubility of gases decreases with increasing temperature and decreasing pressure. Circulation faults, disturbing noises and erosion of protection layers (erosion corrosion) are the consequences. Experience has shown that no system malfunctions due t

47、o nitrogen bubbles have to expected with nitrogen contents of 10. 5.2.3.4 Organic substances Insoluble and soluble organic substances analytically determined as TOC or DOC can both affect the water treatment techniques and further microbiological reactions in the circulation water. PD CEN/TR 16911:2

48、015CEN/TR 16911:2015 (E) 13 5.2.4 Oils/greases The contamination of circulation water by oils or greases e.g. due to the inflow of operating fluids or due to valves, pipes, heating surfaces, etc. that have been treated with a temporary corrosion protection and with processing aids can cause massive

49、malfunctions. As a film or coating on heated surfaces, oils and greases hamper heat transfer and can, alone or in connection with other substances, cause malfunctions of the regulation and safety devices. Oils and greases are nutrients for microorganisms and therefore increase the probability of microbiologically influenced corrosion processes. 6 Systems engineering 6.1 Systems conception 6.1.1 General For reasons related to corrosion, district heating facilities have to be designed and operated in such a way that the inflow of air is, as f