1、API MPMSwLS.LD 73 0732290 O526656 242 Date of Issue: June 1994 Affected Publication: API Chapter 19.1D, Documentation File for APl Manual of Petroleum Measure- ment Standards Chapter 19.lD-Evaporative Loss from Fixed Roof Tanks MI Builelin 2.5181, Fust Edition, March 1993 (first printing) ERRATUM Th
2、e corrected Table of Contents is shown on the following page: API PUBLICATION 2518 DOCUMENTATION FILE CONTENTS SECTION PAGE DESCRIPTION - INTRODUCTION . 1 !STANDING STORAGE LOSS A B Development of Vapor Space Expansion Factor, KE . Al Development of Vented Vapor Saturation Factor, Ks . B1 C D E F De
3、velopment of Vapor Space Temperature Factor, KT . C1 Development of Solar Insolation Parameters D1 Development of Paint Solar Absorptance, Q . El Development of Liquid Surface Temperature Equations . F1 G Sensitivity Analysis of Standing Storage Loss Equation G1 H Comparison of Standing Storage Loss
4、 Equation with Test Data . i . H1. REFERENCES R1 API MPMS*LS.LD 93 m 0732290 051LY39 9Y7 m Documentation File for API Manual of Petroleum Measurement Standards Chapter 19.1 - Evaporative Loss From Fixed Roof Tanks API Bulletin 25181 API PUBLICATION CHAPTER 19.1 D FIRST EDITION, MARCH 1993 American P
5、etroleum Institute 1220 L Street, Northwest 4 Washington, D.C. 20005 API MPMS*LS.LD 93 0732290 05LL440 667 Documentation File for API Manual of Petroleum Measurement Standards Chapter 19.1-Evaporative Loss From Fixed Roof Tanks API Bulletin 25181 Measurement Coordination API PUBLICATION CHAPTER 19.1
6、 D FIRST EDITION, MARCH 1993 American Petroleum Institute API MPMS*L9*LD 93 0732290 05LL44L 5T5 SPECIAL NOTES 1. API PUBLICATIONS NECESSARILY ADDRESS PROBLEMS OF A GENERAL NATURE. WITH RESPECT TO PARTICULAR CIRCUMSTANCES, LOCAL, STATE, AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED. 2. API IS N
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12、pyright O 1993 American Petroleum Institute API MPMS*:LS.LD 93 W 0732290 0533442 433 FOREWORD API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no re
13、presentation, warranty, or guarantee in connection with this pub- lication and hereby expressly disclaims any liability or responsibility for loss or damage re- sulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict. Suggeste
14、d revisions are invited and should be submitted to the director of the Measure- ment Coordination, Industry Services Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. iii API MPMS*LS*LD 93 0732290 0533443 378 API PUBLICATION 2518 WCUMENTATION FILE CONTENTS PAGE S
15、ECTION DESCRI PTIN - INTRODUCTION 1 STANDING STORAGE LOSS Development of Vapor Space Expansion Factor, KE . Al Development of Vented Vapor Saturation Factor, KS . B1 A B Development of Vapor Space Temperature Factor, KT . CI Deve1 opment of Sol ar Insol at i on Parameters. . D1 Development of Liquid
16、 Surface Temperature Equations . F1 Development of Paint Solar Absorptance, Q . El Sensitivity Analysis of Standing Storage Loss Equation G1 Comparison of Standing Storage Loss Equation with Test Data . H1. WORKING LOSS Development of Working Loss Equation I1 Development of Product Factor, Kp . K1 D
17、eveopment of Turnover Factor, Q 31 Comparison of Working Loss Equation with Test Data L1 REFERENCES R1 API MPMS*LS.LD 93 m 0732290 05LL444 204 m 3 API PUBLICATION 2518 DOCUMENTATION FILE INTRODUCTION This document is the Documentation File to API Publication 2518, Second Edition A7*. The purpose of
18、the Documentation File is to present detailed technical infomation related to the development of AN. Publication 2518 that includes: (I) the development of theoretical equations; (2) comparisons with test data; (3) a sensitivity analysis of the loss equation; and (4) other pertinent information that
19、 was developed during the preparation of API Publication 2518. The Documentation File is divided into two main parts: Sections A through H pertain to the standing storage loss, and Sections I through L pertain to the worki ng 1 oss. The standing storage loss equation in the Second Edition A71 is dif
20、ferent then that in the First Edition A6. Sections A through H present the development of the new standing storage loss equation. The working loss equation in the Second Edition A71 is the same as that in the First Edition A6. Sections I through L contain development information that originally appe
21、ared in the First Edition. Section R contains a list of important References that were reviewed in developing the Second Edition. These references are cited in various sections of the Documentation File. Numbers in brackets refer to the numbered references listed at the end of this Documentation Fil
22、e. t 1 API PUBLICATION 2518 CUMENTATION FILE SECTION A DEVELOPMENT OF VAPOR SPACE EXPANSION FACTOR, KE Al Al .O A2.0 A3.0 A4.0 A4.1 A4.2 A4.3 A4.4 A4.5 A5.0 Al Al .API MPMS*LSnLD 93 m 0732290 O533446 087 m API W6LICATION 2518 DOCUMENTATION FILE SECTION A CONTENTS DESCRIPTION PAGE - NOMENCLATURE . .
23、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A3 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A4 VAPOR SPACE VOLUME CHANGE . . . i . . . . . . . . . . . . . . . . . . . . . . A4 VAPOR SPACE EXPANSION FACTOR. . . . . . .
24、. . . . . . . . . . . . . . . . . A9 SIMPLIFIED EQUATIONS FOR THE VAPOR SPACE EXPANSION FACTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A9 Neglecting the Term PBp . . A9 Replacement of Tyl With TM. . A9 Replacement of Py2 With PvA . . . . . . . . . . . . . . . . . . . . . .
25、. . A10 Use of a-Simplified Equation for the Vapor Pressure Range, APy . . A10 Neglecting the Term APB . . . . . . . . . . . . . . All CONCLUSION. . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A12 TABLES Value of the Variables at the Maximum and Minimum Conditions .
26、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5 FI6RES Schematic of the Tank Vapor Space Heating Process and the Resulting Volume Expansion Due to the Thermal Breathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A13 A
27、PI MPMS*LS*LD 93 m 0732290 05LL447 TL3 m A B KE n P AP R T AT V AV Y A ATM 8 BP BV L LA T V VA 1 2 API WBLICATIW 2518 DOCUMENTATION FILE SECTION A NOMENCLANRE DESCRI PT ION Vapor pressure function constant Vapor pressure function constant Vapor space expansion factor Number of mol es Pressure Pressu
28、re change Ideal gas constant (10.731) Temper at Ure Temperature change Vol Ume Vol Ume change Mole fraction in the vapor phase SUBSCRIPTS Air Atmospheric Breather Vent Breather Vent Pressure Setting Breather Vent Vacuum Setting Liquid Liquid Average Total Stock Vapor Vapor Average Initial Condition
29、or Minimum Condition Final Condition or Maximum Condition UNITS - di mens i on1 es s OR dimensionless mol e psi psi psia ft3/l bmole OR OR OR ft3 ft3 mol e f racti on A3 Al -0 INTRODUCTION This section of the Documentation File to API Publication 2518, Second Edition, contains a derivation of the eq
30、uation for the vapor space expansion factor, KE. This equation is derived from the ideal gas law and from the pressure, temperature and volume conditions that exist in the vapor space of a fixed-roof tank containing a volatile liquid stock. Section A2 presents a derivation of the vapor space volume
31、change due to thermal breathing. This derivation closely follows that originally derived by Boardman i* and that. presented at the API “Symposium on Evaporation Loss of Petroleum from Storage Tanks“ November 10, 1952 2. Section A3 defines the vapor space expansion factor, KE, and develops the equati
32、on that may be used to calculate this factor. Section A4 describes various simplifications that can be made to the equation for the vapor space expansion factor to permit ease of calculation with little loss in accuracy. A2-O VAPOR SPACE VLWE CHANGE Figure Al is a schematic illustrating the tank vap
33、or space thermal breathing process in a fixed-roof tank that is partially filled with a volatile liquid stock and equipped with a pressure-vacuum vent. During the thermal breathing process, the pressure, volume. and temperature vary from minimum condition 1 to maximum condition 2. At conditions 1 an
34、d 2, the total absolute pressure in the vapor space is Pl and P2, respectively, where: - Numbers in brackets refer to the numbered references listed at the end of this Documentation File. A4 API MPMS*L-LD 93 m 0732290 0533449 B9b =, During the thermal breathing process, the pressure, volume and temp
35、erature vary from a certain combination of values at the minimum condition to be certain combination of values at the maximum condition. At the minimum condition 1, it is assumed that all of the variables are simultaneously at their minimum values; and at the maximum condition 2, it is assumed that
36、all of the variables are simultaneously at their maximum values. lhe value of the variables at the minimum condition i and maximum condition 2 are listed in Table Al. Table Al - Value of the Variables at the Hinimupi and iaximm Conditions Variable Gas space total pressure Atmospheric pressure Gas sp
37、ace gage pressure Stock vapor pressure Ai r part i al -pressure 6as volume Gas temperat Ure Liquid surface temperature Units psia psia Psig psi a PJ i ft3 OR OR Minimum Condition 1 I Maximum Condition 2 From the ideal gas law, the total number of moles of gas, nT, in an enclosed volume, V, at temper
38、ature, T, and pressure, P, is given by: PV nT - - RT (A-3 1 Assume that the gas mixture in the tank vapor space is a two-component mixture consisting air and stock vapor. The mole fraction of air, YA, and the mole fraction of stock vapor, yv, may be determined by Eqs (A-4) through (A-7): AS API flPf
39、lS*LT.lD 93 W 0732290 05LL450 508 W nA YA = - “T “V Yy = - nT pV Yy = - P The mole fraction of air, YA, may be expressed in terms of the mole fraction of vapor, yy, as follows: (A-8) During the thermal breathing process of the tank vapor space, the number of moles of air, nA, in the volumes, Vi and
40、Vp, is assumed to remain the same. This assumption may be expressed as follows: We may substitute Eq (A-4) into Eq (A-9) to yield: YA1 nT1 = YA2 n12 We may substitute Eq (A-3) into Eq (A-10) to yield: plVI p2v2 yA1 cl = yA2 iI k We may substitute Eq (A-7) into Eq (A-13) to yield: (A- 12) (A-13) v2 =
41、 v1 ; : p” pv2 k (A- 14) Using Eq (A-14), the volume change due to thermal breathing, AV, may be determined as follows: (A-15) AV = V2 - V1 (A-16) We may substitute Eqs (A-1) and (A-2) into Eq (A-16) to yield: A7 API MPMS*LS.LD 93 0732290 05LL452 380 (A-17) AV = V1 I + (V2 - Vi) - (BP - BV) 1 (2 ilT
42、l) 1 (A-18) p + p - pv2 It .is a convenient to define the terms APy, APg and ATy as follows: APV = QV2 - QVl (A-19) APB = PBP - PBV (A-20) ATv = 12 - T1 = Tv2 - TV1 (A-21) We may substitute Eqs (A-19), (A-20) and (A-21) into Eq (A-18) and expand the terms to yield: APV - APB AV = V1 l + ATM + BP .-
43、(A-22) (A-23) Since the terms (ATV/Tyl) and (APy - APB)/(PA + PBP - Pyp) are small, their product can be considered negligable. Thus, the product term in Eq (A-23) can.be neglected. Eq (A-23) then simplifies to the following: APV - APB AV = Il k t P + p - pv2 (A-24) A8 API flPflS*:LS-LD 93 U 0732290
44、 0511453 217 I m A3.0 VAPOR SPACE EXPANSION FACTOR The vapor space expansion factor, KE, is defined as the ratio of tile vo change, AV, to the initial volume, Vi, as follows: AV KE - v1 Substituting Eq (A-24) into (A-25) we obtain: - TV1 ATM BP - Y2 urne (A-25) (A-26) A4.0 SIMPLIFIED EQUATIONS FOR T
45、HE VAPOR SPACE EXPANSION FACTOR Eq (A-26) may be simplified for ease of calculation. Sections A4.1 through A4.4 present various simp1 i.fications that can be made. A4.1 Neqlectincr the Term Pw It should be noted that PBP is small (about 0.03 psi) compared to PATH (about 14.7 psia) and can be neglect
46、ed in the denomination of Eq (A-26) to yield: (A-27) A4.2 Replacement of Tvi With TI A In the first tem of Eq (A-27), the minimum vapor space tmperature, TV1, is close to the daily average liquid surface ,temperature, TLA, since both are absolute temperatures. Thus, for ease of calculation, we can r
47、eplace TV1 with TLA in Eq (A-27) to yield: A9 API RPRS*L9*1D 93- 0732290 0511454 153 H AT“ APV - APS KE = - + T p - pv2 (A- 28) A4.3 Replacement of Pv7 With Pvq For low vapor pressure stocks, the stock vapor pressure, Pv, is small compared to atmospheric pressure, PA. Thus, we may replace the stock
48、vapor pressure -at the minimum liquid surface temperature, Pvp, with the stock vapor pressure at the daily average liquid surface temperature, PVA, in Eq (A-28) to yield: (A- 29) Eq (A-29) appears as Eq 4 in Ref. A7. A4.4 Use of a Simplified Equation for the Vapor Pressure Range, APy The vapor press
49、ure of the stock may be determined from Eq (A-30), where the vapor pressure function constants A and B must be selected for the particular stock see Tables 4 and 5 in Ref. A7. (A-30) We can determine the slope of the vapor space pressure function by taking its derivative with respect to the liquid surface temperature, TL, as follows: dP, 6 Py -t- Eq (A-31) can be written in differential form as follows: (A-31) A10 API MPMS*19=1D 93 0732290 0511455 09T (A-32) Eq (A-32) gives the vapor pressure range, A
