1、GPA Standard 8195-95 Tentative Standard for Converting Net Vapor Space Volumes to Equivalent Liquid Volumes Reprinted 1997- 1998 Gas Processors Association 6526 East 60th Street Tulsa, Oklahoma 74145 GPA 8195-95 Errata Sheet September 1 1999 Please note the following errata in GPA Publication 8195-9
2、5: _Page 4 - Equation 5.7 The equation should read: f= 0v / (G x 8.3372) Pae 5 - Table 5.1 Upper portion of the table - Column (a) - all liquid volume percents should move up one space to be: C2 3.00 C3 95.00 IC4 0.50 NC4 1.50 Middle portion of the table - all components listed in the leit most colu
3、mn should move up one space so that N2 corresponds with a critical temperature of-232.51, CO2 corresponds with a critical temperature of 87.75, etc., etc. Page 7 - Figure 6.2 - F Factor Determination The bottom line on the graph represents 0.45 relative density. The second line up from the bottom re
4、presents both the 0.425 and the 0.475 relative densities. The third line up from the bottom represents 0.400 relative density. DISCLAIMER GPA publications necessarily address problems of a general nature and may be used by anyone desiring to do so. Every effort has been made by GPA to assure accurac
5、y and reliability of the information contained in its publications. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed. It is not the intent of GPA to assume the duties of employers, manufacturers, or suppliers to warn and properly train emplo
6、yees, or others exposed, concerning health and safety risks or precautions. GPA makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any fed
7、eral, state, or municipal regulation with which this publication may conflict, or for any infringement of letters of patent regarding apparatus, equipment, or method so covered. 1.0 2.0 TENTATIVE STANDARD FOR CONVERTING NET VAPOR SPACE VOLUMES TO EQUIVALENT LIQUID VOLUMES SCOPE delivery for pressure
8、s up to 280 psia. For 1.1 The purpose of this standard is to present practical field methods for determining net deliveries of LPG, raw make, and NGL into or out of closed pressurized containers such as rail cars, barges, and transport trucks, by applying net vapor space corrections to the indicated
9、 liquid volumes from level measurements. 1,2 Products to which this method may be applied include commercially available LPGs and NGLs (raw make, E/P mixes, propane, P/B mixes, butanes, natural gasolines, etc.). The intended application relative density range is 0.4 to 0.65. SUMMARY 2.1 2.2 Two opti
10、ons for determining net delivery are included. Method I covers calculations when only relative density, temperature, pressure, and gross liquid volume indications are known. Compressibility corrections are determined using inputs from lookup graphs or tabular data. Method 2 for determining net deliv
11、ery may be used when product composition (liquid volume %) is known and the vapor compressibility factor is calculated using the Pitzer-Curl equation, or another generally recognized correlation. 2.3 Either method may utilize hand calculations and the forms in Appendix A, or the user may develop PC
12、spreadsheet applications discussed in Section 5.2. 3.0 PRECAUTIONS 3.1 3.2 3.3 This method is limited to products in the relative density range of 0.4 to 0.65. If the product is a raw make and composition is not available, the compressibility corrections may have a higher uncertainty than a fraction
13、ated mixture such as E/P with the same relative density. It is estimated that the additional uncertainty for raw make may be as great as +/- 1% of net delivery for high vapor pressure products. It is estimated that results derived from compressibility correction curves instead of calculating correct
14、ions by a PC program may add an additional uncertainty of +/- 0.5% of net pressures above 280 psia, the uncertainty may increase. 3.4 This method is limited to product temperatures of -40 Deg. F to 140 Deg. F. 3.5 Methods for determining gross volumes, relative density, pressure, temperature, and co
15、mposition are not covered by this standard. 4.0 DEFINITIONS 4.1 Compressibility factor - A factor usually expressed as “g“ which gives the ratio of the actual volume of gas at a given temperature and pressure to the volume of gas when calculated by the ideal gas law at that same temperature and pres
16、sure: 4.2 Critical pressure - The pressure necessary to condense a vapor at its critical temperature. 4.3 Critical temperature - The highest temperature at which a fluid can exist as a liquid. Above this temperature, the fluid is a gas and cannot be liquefied regardless of the pressure applied. 4.4
17、LP-gas (liquefied petroleum gas)- Predominantly propane or butane separately or in mixtures which are maintained in a liquid state under the pressure within the confining vessel. 4.5 NGL (natural gas liquids) - Natural gas liquids are those hydrocarbons liquefied at the surface in field facilities o
18、r in gas processing plants. Natural gas liquids include ethane, propane, butanes and natural gasoline. 4.6 Raw mixliquids - A mixture of natural gas liquids prior to fractionation. Also called “raw make“. 4.7 Temperature correction factor - A factor for correcting volumes to that occupied at a speci
19、fic reference temperature. The reference temperature most commonly used in the U.S. petroleum industry is 60F. 5.0 CALCULATION OF NET VAPOR CORRECTION FACTOR (F) FROM COMPOSITION (METHOD 2). 5.1 Given the attached Table 5.1, calculate columns and totals as required. 5.2 5.3 5.4 5.5 5.6 5.7 Propertie
20、s for n-heptane may be used for C6+ when other properties are not available. All needed data are in the GPSA Engineering Data Book or GPA 2145, with the exception of the vapor volatility factor. That factor may be derived from GPSA Engineering Data Book convergence pressure K values. However, the sa
21、me volatility factors may be used in all applications without significant differences in results. The recommended minimum application of the compositional method would be to use the factors given in Table 5.1. Using the following relationships, the user may develop a PC program utilizing commerciall
22、y available spreadsheet software to calculate data similar to Table 5.1. Table 5.1 may be used to verify such programs. Given composition in liquid volume %, multiply: (a)x(b)x(c)=(d) (e)=(d)/sum of (d) (g)=(e)x(f) Vapor molecular weight, MWv= Sum(g) Vapor critical temperature, Te= Sum(e)x(h) Vapor
23、critical pressure, Pc= Sum(e)x(i) Vapor acentric factor, co = Sum(e)x(j) Calculate reduced temperature at conditions: T r = t + 459.67 T e + 459.67 5.1 Calculate reduced pressure at conditions: Pr P Pe 5.2 Calculate the vapor compressibility factor using the Tsonpoulous virial 1 equation: B 0 = 0.14
24、45 - 0.330/T r - 0.1385/Tr2 - 0.0121/Tr3 5.3 B 1 = 0.073 + 0.46/T r - 0.50/Tr2 - 0.097/T 3 - 0.0073/Tr8 5.4 Z = 1 + (B 0 + co B1)Pr/T r 5.5 The vapor density is then calculated from the equation: Pv = P MWv R(t + 459.67)Z 5.6 R=80.27 for density in lb/gal, t in F and P in psia. 5.8 The net vapor cor
25、rection factor is then calculated as: f= Pv G 8.3372 5.7 Where G is the 60F relative density of the fluid. 6.0 PROCEDURE FOR METHOD 1 6.1 With known relative density and temperature, B and F factors are obtained from Figures 6.1 and 6.2. 6.2 The vapor correction is then calculated from the following
26、 equation: f= PF 1-BP 6.1 7.0 EXAMPLE CALCULATIONS 7.1 Vapor space correction factor calculation from composition, see Table 5.1: G = 0.510 t = 60F Po = 130 psig (observed press = 130 psig, atm press = 14.7, P = 144.7 psia) f= 0.04179 7.2 Vapor space correction factor calculation for composition in
27、Table 5.1 from Charts. Use attached charts, Figure 6.1 and Figure 6.2, to determine the values of F and B corresponding to 60F relative density of the fluid and the product temperature. B = 0.00112 F = 0.000238 7.3 Calculate opening and closing vapor correction factors from the following equation: f
28、= PF 1-BP 6.1 f= 0.0411 1Tsonpoulous, C., “An Empirical Correlation of Second Virial Coefficients“, A.I.Ch.E. Journal 20(2), pp. 263-272 (1974). 4 Table 5.1 Calculation of Vapor Space Correction Factor From Composition Component N2 CO 2 H2S C1 C2 C3 i-C 4 n-C 4 i-C 5 n-C 5 C6+ Total Component N 2 CO
29、 2 H2S C1 C2 C3 i-C 4 n-C 4 i-C 5 n-C 5 C6+ Total (a) Liq Vol% 3.00 95.00 0.50 1.50 (b) (c) (d) (e) (f) (g) Volatility (a x b x c) (d/sum of d) Molar (e x f) Ft3/Gal Factor Vap Frac Mass Weighted MW 91.413 95 0 0.0000 28.013 0.000 58.807 7.6 0 0.0000 44.010 0.000 74.401 2.9 0 0.0000 34.080 0.000 59.
30、135 16 0 0.0000 16.043 0.000 37.476 3.6 404.741 0.1043 30.070 3.136 36.375 1 3455.625 0.8903 44.097 39.261 30.639 0.43 6.587 0.0017 58.123 0.099 31.790 0.3 14.306 0.0037 58.123 0.214 27.393 0.12 0 0.0000 72.150 0.000 27.674 0.09 0 0.0000 72.150 0.000 24.371 0.02 0 0.0000 86.177 0.000 100.00 3881.259
31、 42.710 (e) (h) (i) 0) (e)x(h) (e)x(i) (e)x0) Critical Critical Acentric Weighted Weighted Weighted Vap Frac Temp Press Factor Crit Temp Crit Pres Acen Fac (Tc) (Pc) (m) 0.0000 -232.51 492.8 0.0372 0.0 0.0 0.0000 0.0000 87.75 1069.5 0.2667 0.0 0.0 0.0000 0.0000 212.45 1300.0 0.0948 0.0 0.0 0.0000 0.
32、0000 -116.67 667.0 0.0104 0.0 0.0 0.0000 0.1043 90.09 707.8 0.0979 9.4 73.8 “ 0,0102 0.8903 205.97 615.0 0.1522 183.4 547.6 0.1356 0.0017 274.46 527.9 0.1852 0.5 0.9 0.0003 0.0037 305.58 548.8 0.1995 1.1 2.0 0.0007 0.0000 369.03 490,4 0.2280 0.0 0.0 0.0000 0.0000 385.77 488.1 0.2514 0.0 0.0 0.0000 0
33、.0000 451.80 439.5 0.2994 0.0 0.0 0.0000 0.0 0.0 0.0000 194.4 624.3 0.1468 G 0.5100 (60F/60F) t 60F Observed Pressure 130.0 psig Atmospheric Pressure 14.7 psia p 144.7 psia Tr 0.7946 B o -0.5143 B 1 -0.3794 Pr 0.2318 Z 0.8337 Pv 0.1777 Ib/gal f 0.041794 5 Figure 6.1 B Factor Determination (B x 1,000
34、) 10.00 9.00 8.00 7.00 6.00 0 0 0 ,.: 5.00 X 4.00 3.00 2.00 1.00 0.00 -40 -20 0 20 40 60 80 Product Temperature (F) 100 120 140 6 Figure 6.2 F Factor Determination (F x 10,000) 4.50 4.00 3.50 t I I I l t f I i I 7 i I 1 , I i I t I l I I I I I l I I , I I I I I I I I I I , , I I i t i I II i I I , i
35、 i i I I i I I T-“T- - I I 5 I I I t I l ; I I I , L 1 I J I u “r - - i t I , t I I I ! t:l, iii III T, ;i, ,11 ,:1 IRelative Density (60F/60F) 0 0 o o 3.00 X 2.50 2.00 1.50 i .T“-? I I ._! I I i I I I I I i t I I I i_L I I .+-.-. I l - 0.650 - 0.625 l 0.600 0 0.575 .L 0.550 I 11 F - ALGEBRAIC VARIA
36、BLE I ; I I 12 VAPOR TO EQUIVALENT LIQUID FACTOR (f) (DETERMINE FROM METHOD 1 OR 2) I ; I I 13 EQUIVALENT LIQUID VOLUME BBL BBL L BBL GAL GAL GAL GAL 60F (9 X 12) I i I 14 TOTAL LIQUID VOLUME 60F (8 + 13) BBL GAL NET LIQUID VOLUME - RECEIVED 60F (14 FINAL-14 INITIAL) BBL GAL BEFORE LOADING O.B.Q. (1
37、4 INITIAL) 15 16 17 BBL GAL NET LIQUID VOLUME-DISCHARGED 60F (14 INITIAL-14 FINAL) 18 R.O.B. AFTER UNLOADING (14 FINAL) BBL GAL t:!:!:i: i ;! i iii i iii t i i i ! i i! i!i!ii!i!iii tit t! i !iit :i:i i:! !i ! ii i. i i t: : t: i:ii!i!:i !i .i .i: !i:i! iiiiiiiiiiiiiiiiiiiiiii!liiiiiii!iiiiii !iiiii
38、iiili!ii!i!i BBL GAL BBL GAL BBL GAL * In the absence of measured relative density, use actual liquid relative density. A-1 All volumes corrected to 60F Vessel Identification Load Date Load Location Order Number Discharge Date Discharge Location Loaded Quantity (Cargo Certificate) Bbls.Net (1) Recei
39、ved vs.LoadedDifference (4) - (1) = Bbl. Vessel at Load Location (2) (3) (4) Bbls. After Loading Bbls. Before Loading O.B.Q. Bbls. Received V.H.E.F. Adjusted Bbls. Net Difference (8) - (1) = (8) - (1) x 100 = (1) Bbl. % Unloaded vs. Discharged Difference (8) - (7) = Bbls. Unloaded Quantity (8) Net B
40、bls. Vessel In-Transit Difference (5) - (2) = R.O.B.Difference (3) - (6) = Vessel at Discharge Location (5) Bbls. on Arrival (6) Bbls. R.O.B. (7) Bbls. Discharged V.H.E.F. Adjusted Bbls. Bbls. Bbls. Reconciliation by Product Load Location Discharge Location Ship to Received Loss/Gain (8)- (1) Loaded
41、 Received Vessel Unloaded Quantity Quantity Quantity Quantity Bbls % Product (1) (4) (7) (8) Totals Vessel to Vessel Loss/Gain (7)- (4) Bbls. % Comments A-2 Sample Calculation NET LIQUID VOLUME CLASSIFICATION SHEET TYPE OF VESSEL Rail Car DATE VESSEL IDENTIFICATION WRNX 1993 WATER CAPACITY 30,900 PR
42、EVIOUS CARGO Propane LOCAL AVERAGE ATMOS. PRESSURE 14.73 psia 9/16/93 GAL. 1 VESSEL GAUGE 2 GROSS LIQUID VOLUME (FROM VESSEL STRAPPING TABLES) 3 OBSERVED TEMPERATURE (OF) 4 OBSERVED PRESSURE (PSIG) 5 OBSERVED REI.ATIVE DENSITY RELATIVE DENSITY 60/60F (ASTM Table 23 or GPA 2142 Tab.2)* VOLUME CORRECT
43、ION FACTOR (ASTM Table 24 or GPA 2142 Tab.l) LIQUID VOLUME 60F (2 X 7) VAPOR VOLUME (WATER CAPACITY - 2) RECEIVED INITIAL 0% BBL 00AL 90 FINAL 90% BBL 27,810 GAL 70 120 DISCHARGED INITIAL 92% BBL 28,428 o 80 125 FINAL 0% BBL 0 GAL 70 100 190 I I I NIA .502 .494 N/A I I I 510 .510 .510 .510 I I t N/A
44、 .9838 .9670 N/A BBL 27,490 GAL BBL 2,472 CAL BBL 0 OAL BBL 30,900 GAL BBL 27,359 G BBL 3,090 AL BBL 0 c, BBL 30,9006AL 10 B - ALGEBRAIC VARIABLE I .00095 .00105 I .00100 .00105 11 F - ALGEBRAIC VARIABLE I .000228 !1 .000235 I .000230 tl .000235 12 VAPOR TO EQUIVALENT LIQUID FACTOR (f) (DETERMINE FR
45、OM METHOD 1 OR 2) .05795 .03688 .03736 .03065 BBL BBL BBL BBL 1,791 aAL , 114 aAL , 92 AL , 947 GAL BBL 27,473 o 13 EQUIVALENT LIQUID VOLUME 60F (9 X 12) 14 TOTAL LIQUID VOLUME 60F (8 + 13) 15 NET LIQUID VOLUME - RECEIVED 60F (14 FINAL-14 INITIAL) BEFORE LOADING O.B.Q. (14 INITIAL) BBL 27,582 OAL 16
46、 17 NET LIQUID VOLUME-DISCHARGED BBL 25,682 CAL BBL 1,791 BBL 1,791 CAL BBL 947 GAL :i:i:i:i:i:!:!:!:i:!:!:i:i:i:!:!(:.:i!:i! iiiiiiiiiii!ii iiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiii iiiiiill BBL 60F (14 INITIAL-14 FINAL) 18 R.O.B. AFTER UNLOADING (14 FINAL) F 26,635 GAL BBL 26,635 AL * In the absence
47、of measured relative density, use actual liquid relative density. A-3 Appendix B Method Used to Construct Charts The charts in Figure 6.1 and 6.2 were constructed using the procedure for calculating F and B from composition with an assumed composition. The fluid was assumed to be a blend of the two
48、normal paraffins which have relative densities nearest the target relative density. For example, a fluid having a relative density of 0.450 is assumed to be a blend of ethane and propane only. The composition was then adjusted until the relative density calculated using the COSTALD liquid density me
49、thod matched the target value. The final compositions used to construct the charts are given in Table B.1. Relative Density_ (60/60) 0.400 0.425 0.450 0.475 0.500 0.525 0.550 0.575 0.600 0.625 0.650 Composition in LV% Ethane 70.95 54.37 37.79 21.21 4.60 Propane 29.05 45.63 62.21 78.79 95.40 76.60 44.10 11.70 n-B utane n-Pentane n-Hexane 23.40 55.90 88.30 66.00 13
