BS EN 12213-1999 Cryogenic vessels - Methods for performance evaluation of thermal insulation《低温容器 热绝缘性能评估方法》.pdf

1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12213:1999 The Euro

2、pean Standard EN 12213:1998 has the status of a British Standard ICS 23.020.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Cryogenic vessels Methods for performance evaluation of thermal insulationBS EN 12213:1999 This British Standard, having been prepared under the direc

3、tion of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 April 1999 BSI 04-1999 ISBN 0 580 30605 4 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standard is the English language

4、 version of EN 12213:1998. The UK participation in its preparation was entrusted to Technical Committee PVE/18, Cryogenic vessels, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals fo

5、r change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international

6、 or European 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 Standard does not purport to include all

7、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 pages This document comprises a front cover, an inside front cover, the EN title

8、page, pages 2 to 10, an inside back cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserve

9、d worldwide for CEN national Members. Ref. No. EN 12213:1998 E EUROPEAN STANDARD EN 12213 NORME EUROPE ENNE EUROPA ISCHE NORM November 1998 ICS 27.200 Descriptors: pressure vessels, cryogeny, definitions, tests, estimation, characteristics, thermal insulation, testing conditions English version Cryo

10、genic vessels Methods for performance evaluation of thermal insulation Re cipients cryoge niques Me thodes de valuation de la performance de lisolation thermique Kryo-Beha lter Verfahren zur Bewertung des Wa rmeda mmvermo gens This European Standard was approved by CEN on 4 September 1998. CEN membe

11、rs 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-to-date lists and bibliographical references concering such national standards may be obtained on application

12、 to the Central Secretariat 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 under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the sam

13、e status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 12213:1998 BSI

14、04-1999 Foreword This European Standard has been prepared by Technical Committee CEN/TC 268, Cryogenic vessels, the Secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an indentical text or by endorsement, at the la

15、test by May 1999, and conflicting national standards shall be withdrawn at the latest by May 1999. This European Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. This European Standard is considered to be a supporting standar

16、d to those application and product standards which in themselves support an essential safety requirement of a New Approach Directive and which make reference to this European Standard. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries

17、are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 Introduction 3 1 Scope 3 2 Defin

18、itions 3 3 General conditions for all methods 3 4 Measuring the heat leak by the loss of product method 5 4.1 General 5 4.2 Test procedure 5 4.3 Determination of the heat leak in units of energy per unit time 5 4.4 Determination of the heat leak as a percentage of product lost per 24 h 5 5 Determina

19、tion of the holding time (open system) in days from heat leak data 6 6 Holding times for closed systems 6 6.1 Determination of the the equilibrium holding time from heat leak data 6 6.2 Determination of the optimum equilibrium holding time from heat leak data 6 6.3 Static experimental holding time 7

20、 7 Test report 7 8 Bibliography 7 Annex A (normative) Conversion of measured volumetric gaseous flow to mass flow 7 Annex B (normative) Correction of measured mass flow rate with regard to deviation from reference conditions 8 Annex C (normative) Equivalent loss determination, for product other than

21、 the test product 10Page 3 EN 12213:1998 BSI 04-1999 Introduction Traditionally in Europe, there have been different ways of defining the insulation performance. A requirement exists therefore to harmonize such methods of evaluating insulation performance for different cryogenic vessels. To aid the

22、understanding of this standard, see the logic diagram in Figure 1. 1 Scope This standard defines a pratical method for determining the heat leak performance of cryogenic vessels. The methods include measurement on both open and closed systems. This standard neither specifies the requirement levels f

23、or insulation performance nor when the methodology defined is applied. These requirements may be defined in design or operational standards/regulations. 2 Definitions For the purpose of this standard, the following definitions apply. 2.1 open system during test, a system is considered open when it i

24、s kept at a constant pressure (e.g. atmospheric pressure) and when the gas produced by the evaporation of the test fluid is continuously released to the atmosphere 2.2 closed system during test, a system is considered closed when the mass of the contents is kept constant with no input or output of p

25、roduct 2.3 heat leak performance the quantity of heat transferred per unit time from the ambient air to the contents of the inner vessel NOTE In an open system the heat leak causes a loss of product. In a closed system it causes a rise in pressure. 2.4 holding time, open system the time expected to

26、elapse from initial filling level until the vessel is empty (no more liquid), calculated from heat leak data 2.5 holding time, closed system the time elapsed from establishing the initial filling condition until the pressure has risen, due to heat leak, to the set pressure of the pressure limiting d

27、evice NOTE A pressure limiting device is either a safety valve or a rupture disc or a back pressure regulator or any other device installed to limit the system pressure under normal operating conditions. 2.5.1 equilibrium holding time the holding time calculated from a specified heat leak assuming t

28、hat liquid and vapour are constantly in equilibrium 2.5.2 optimum equilibrium holding time the equilibrium holding time calculated from heat leak data for a vessel when filled with the quantity of product giving the longest holding time 2.5.3 static experimental holding time a) when the critical pre

29、ssure is greater than the set pressure of the limiting device, the holding time of a closed system measured on a stationary vessel filled with a quantity of product which is calculated to fill the tank to its gross volume without hydrostatic deformation, with saturated liquid at the set pressure of

30、the pressure limiting device b) when the critical pressure is less than the set pressure of the limiting device, the holding time of a closed system measured on a stationary vessel initially filled with the least mass of the specified product determined as follows: the maximum allowable mass of fill

31、ing; or the quantity of product which fills the vessel to its gross volume, without hydrostatic deformation, with liquid saturated to 99 % of its gross volume at the critical pressure. 3 General conditions for all methods The measurements described in this standard shall be carried out under the fol

32、lowing conditions. 3.1 The cryogenic fluid used for testing shall be chosen by the manufacturer. Liquid nitrogen should normally be used except in cases where the vessel to be tested is designed for a specific cryogenic fluid. 3.2 The liquid and gaseous phases shall be in equilibrium at the beginnin

33、g of a test. When a test is carried out at a higher pressure than one bar gauge, it is important that the liquid equilibrium pressure is not lower than this test pressure. 3.3 The test environment shall be stable and constant during the test. It shall be as close as possible to the following referen

34、ce conditions: ambient temperature: 158C; atmospheric pressure: 1 013 mbar. For products except carbon dioxide and nitrous oxide: vessel reference pressure: 1 013 mbar. For carbon dioxide and nitrous oxide: vessel reference pressure: 15 bar (gauge). BSI 04-1999 Page 4 EN 12213:1998 Figure 1 Logic di

35、agramPage 5 EN 12213:1998 BSI 04-1999 3.4 The vessel and its contents shall have reached a stable temperature before the beginning of the measuring period. Equilibrium conditions are obtained after a period of stabilization, the duration of which depends on the size of the vessel and the type and co

36、nfiguration of the insulation. 3.5 All accessories of the vessel which can have an influence on the result of the measurement shall be clearly defined and specified in the report. 3.6 All instrumentation used shall be periodically verified by calibration. 3.7 It is not necessary to use the method de

37、fined in this standard to evaluate the insulation performance resulting from small modifications (this evaluation can be obtained by simple extrapolation). 4 Measuring the heat leak by the loss of product method 4.1 General There are two methods of measuring the heat leak: by direct measurement of l

38、oss of mass; by indirect measurement of loss of mass by measuring the gaseous volumetric discharge rate. The filling level shall be (50 10) % of the maximum filling level at the start of measurement, unless otherwise stated. The ambient temperature and the operating pressure at the top of the vessel

39、 shall be recorded throughout the test so as to be used for correction purposes. The temperature sensor(s) shall be placed in the immediate proximity of the test object, but sited such that they are unaffected directly by cold gas discharged from the vents. The minimum measurement duration shall be

40、24 h after stable conditions have been reached. During the test precautions shall be taken to avoid agitation of the liquid. When measuring the rate of discharge of gas escaping from the vessel by a flow meter, it is essential that the entire gas flow passes through the meter. The gas flow rate shal

41、l be determined as a mass flow rate either by: using a mass flow meter; or using a volumetric flow meter. An appropriate method is shown in annex A. 4.2 Test procedure The test procedure shall be as follows: step 1 : vessel precooling; step 2 : stabilization; step 3 : adjustment of the filling to th

42、e intended starting level (e.g. 50 % 10 %); step 4 : connection of instrumentation (e.g. gas flow meter); step 5 : second stabilization period; step 6 : determination of mass of contents of vessel at start of measuring period; step 7 : a sufficient number of readings shall be taken to establish an a

43、cceptable thermal equilibrium before the start of the measuring period; step 8 : measuring period shall be at least 24 h; step 9 : determination of the loss of product in mass units (when gaseous flow is measured) in accordance with annex A; step 10 : reduction to reference conditions in accordance

44、with annex B. 4.3 Determination of the heat leak in units of energy per unit time The rate of product loss (kg/s) during the measurement period, corrected to the reference conditions in accordance with annexes A and B, shall be converted to an equivalent heat leak, Q,b y multiplying it by the latent

45、 heat of evaporation (J/kg) of the product at the reference conditions. To calculate the heat leak with a product other than the test product, compensation using linear extrapolation in accordance with annex C may be applied but only if the difference between the boiling temperature of these product

46、s at the reference conditions does not exceed 208C. 4.4 Determination of the heat leak as a percentage of product lost per 24 h Based on the result obtained in accordance with 4.3, the heat leak as a percentage of product lost per 24 h is calculated as follows: a) correct the measured heat leak to r

47、eference condition for the test product by linear extrapolation as specified in 4.3; b) calculate the equivalent loss of the test product per day in accordance with the formula: L = 100 % 86 400Q hF where F is the maximum allowable filling mass of the test product (kg); L is the equivalent loss of p

48、roduct in % of F per day; Q is the heat leak (W); h is the latent heat of vaporisation (J/kg) at the vessel reference pressure (see 3.3); 86 400 is the number of seconds per day. All product related data shall be taken at correct reference conditions for the specified product. Annex C may be used to

49、 determine the equivalent loss of product in % of full tank content per day, for product other than the test product.Page 6 EN 12213:1998 BSI 04-1999 5 Determination of the holding time (open system) in days from heat leak data The holding time in days is equal to for the 100 L specified product, which is equivalent to 100 times the reciprocal of the loss of product per 24 h in percent (as determined in 4.4). 6 Holding times for closed systems 6.1 Determination of the equilibrium holding time from heat leak dat