1、 Manual of Petroleum Measurement Standards Chapter 11Physical Properties Data Section 1Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils Adjunct to: ASTM D 1250-04 and IP 200 MAY 2004 ADDENDUM 1, SEPTEMBER 2007 REAFFIRMED, AUGUST 20
2、12 Manual of Petroleum Measurement Standards Chapter 11Physical Properties Data Section 1Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils Adjunct to: ASTM D 1250-04 and IP 200 Measurement Coordination MAY 2004 ADDENDUM 1, SEPTEMBER
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16、esulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict. Suggested revisions are invited and should be submitted to API, Standards department, 1220 L Street, NW, Washington, DC 20005, standardsapi.org. CONTENTS Section 1 Temp
17、erature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils.1 11.1.0 Implementation Guidelines 1 11.1.1 Introduction IP 200; ANSI/ASTM D 1250), and later in their 20C tables. The implementation procedures are now incorporated in this Standard. Fo
18、r business reasons the Tables have been extended to lower temperatures and higher densities (i.e., lower API gravities). Real-time density measurement using density meters has become more prevalent in the industry for input into VCF calculations. These density measurements are often made at pressure
19、s greater than atmospheric. This pressure effect must be taken into account simultaneously with any temperature effect when determining the density at standard conditions. Hence, pressure and temperature corrections have been combined into one procedure. Rounding and truncation of initial and interm
20、ediate values have been eliminated. Rounding will only be applied to the final VCF values. The previous Standard used a format that resulted in CTL values rounded 4 or 5 decimal digits, depending upon whether the CTL value was greater than or less than one. The final VCF values will now be rounded t
21、o a consistent 5 decimal digits. The Standard also provides a mechanism to provide unrounded factors that, when combined, give the overall rounded CTPL. Implementation procedures needed to be updated to reflect changes in computer technology. The 1980 Tables implementation procedure used integer ari
22、thmetic in order to allow all existing computer equipment to achieve consistent results. With the advent of the IEEE Standards and the predominance of 32 bit and higher level machines, this complexity of the 1980 procedure was no longer needed. This procedure now uses a double-precision floating-poi
23、nt math procedure. Flow computers in the field became common for real-time measurement of petroleum fluids. These require improved convergence methods for the correction of observed density to base density. A more robust convergence scheme now accomplishes this calculation. The range of application
24、for the 1980 Chapter 11.2.1 method has been extended to be consistent with the range used here. This is so that a single pressure correction method could be used. Since the 1980 Chapter 11.2.1M method was not completely consistent with the 11.2.1 method, it has been withdrawn. The implementation pro
25、cedure for the pressure correction is now the standard, not the printed table values. When the number of decimal digits is increased and the floating-point math format used, discrepancies between the previous 60F, 15C and 20C Tables become apparent. Starting from the same input density SECTION 1 VOL
26、UME CORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, NGLs and LPGs are excluded from consideration in this Standard. The combination of density and volume correction factors for both temperature and pressure is collectively referred to in this Standard as a Correction for Temperature and Pressur
27、e of a Liquid (CTPL) (VCF). The temperature portion of this correction is termed the Correction for the effect of Temperature on Liquid (CTL), also historically known as VCF (Volume Correction Factor). The pressure portion is termed the Correction for the effect of Pressure on Liquid (CPL). As this
28、Standard will be applied to a variety of applications the output parameters specified in this Standard (CTL, Fp, CPL, and CTPL) may be used as specified in other API Manual of Petroleum Measurement Standards (MPMS) Chapters. SECTION 1 VOLUME CORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, as ro
29、unded values, they may numerically fall just outside of the actual limits established by the defining values. In 1980 the correlation for CTL was chosen so that it would be monotonic with respect to temperature (both the function and its temperature derivative). It also did not have any discontinuit
30、ies over a very wide range of temperatures and densities. This does not say that the correlation is valid outside the data that was used to generate it. Due to needs of industry to accommodate commerce at temperature and density ranges well outside those originally tested, the limits of density and
31、temperature have been extended. This extension is purely mathematical. The algorithms that correctly predict volume correction within the original test limits have simply been applied to regions beyond the original temperature and density limits. The following figures show the range of the original
32、data, the extensions to give the previous standards, and the current extensions for the Generalized Crude Oils, Generalized Refined Products, Generalized Lube Oils, Special Applications, and the compressibility factors. Computed values in any of these extended regions should be used with caution. Cu
33、rrently, there are no data in these regions to establish uncertainty. SECTION 1 VOLUME CORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, however, thermal expansion factors can be determined and these pure compounds can be treated as a Special Application. It is recognized that there are some pure
34、 components whose densities put them in the range of this Standard and the standard(s) for light hydrocarbons. The two standards give results that are of comparable accuracy but are slightly different. It is up to the contracting parties to decide which is more appropriate to use. SECTION 1 VOLUME C
35、ORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, this is the full VCF. Mathematically, the procedure starts with the density TeTP (, ) (and corresponding volume VVTPTe (, ) expressed at the base temperature T and base pressure Pe. Corrections are made to obtain the density (, )tP (and correspondi
36、ng volume VtP(, ) at the alternate temperature t and gauge pressure P. The thermal correction to an intermediate density (, )tPeis done first: ()()eeTLPTPtC, (1) and then the pressure correction to (, )tP: ()()ePLPtPtC, . (2) Note that the combined correction is simply the product of the first two c
37、orrection factors since: ()()()()()()PLTLeeeeTPLCCPtPtPTPtPTPtC =,. (3) Volume corrections use the same factors since the volume of a fixed mass is inversely proportional to its density: ()()()()eeeeTLPtVPTVPTPtC,= (4) ()()()()PtVPtVPtPtCeePL,= (5()()()()PtVPTVPTPtCeeTPL,= . (6) The density and volu
38、me at temperature t and pressure P can be calculated from the density and volume at base conditions as: () ( )eTPLPTCPt , = (7) ()()TPLeCPTVPtV, = . (8SECTION 1 VOLUME CORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, based on density in kg/m3at 60F the A, B, C, and D values) but several sets of
39、coefficients for the 60 thermal expansion coefficient (the K0, K1, and K2values) depending upon the liquids classification and density at 60F. SECTION 1 VOLUME CORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, this need was made even greater by the inclusion of the pressure correction term in the
40、 procedure. For this reason, a more sophisticated “Newtons Method” is used. Newtons method defines a specific way to calculate a new 60value from the previous value in Step 5 above. The non-linear Equations (16) and (17) are “linearized” about each estimate of the 60value. The equations are lineariz
41、ed by taking the derivative of all of these equations with respect to 60. This linearized equation can then be directly solved for a value of 60that gives the observed density o. The solution of the linearized equation is used as the next iterative steps estimate for 60. Newtons methods have two imp
42、ortant properties: (1) when an estimate is near the actual answer, the method is guaranteed to converge and (2) the convergence of the estimate to the correct answer is very quick. These properties give the power and robustness needed in this Standard. The derivation of the iteration equations is in
43、 Appendix F. The detailed steps to implement the iterative procedure (e.g., how to make the initial estimate, checks to keep values in bounds, convergence tolerances, etc.) are in 11.1.6.2. 11.1.3.6 Calculation of CTL and CPL Factors for Base Temperatures Other Than 60F The goal of this Standard is
44、to provide consistent results when performing corrections using either metric or customary units. That is, when one corrects an observed density to the density at alternate conditions of temperature and pressure, the same result should be obtained irrespective of the base conditions used or the unit
45、s in which they are expressed. For the equations and correlations used in this Standard, the 60F base condition must always be applied in the calculation procedure, even when input and output data are expressed in the metric system of units. It was a desire in this revision to modify the equations i
46、n 11.1.3.3 to enable direct input of densities at each separate base temperature (60F, 15C and 20C). Unfortunately this proved impossible to achieve while keeping all calculations consistent. Because of this, the 60F base condition must be incorporated into all of the CTL and CPL calculations used i
47、n this Standard. See Appendix C for details. SECTION 1 VOLUME CORRECTION FACTORS FOR CRUDE OILS, REFINED PRODUCTS, & LUBE OILS 18 11.1.3.7 Calculation Types Based upon the equations used for this Standard, there are three distinct types of calculations when using the 60F base density. These particul
48、ar classifications are based upon how the calculations are performed each calculation type requires the preceding type(s): Type 1. Starting with the density at the 60F and 0 psig base condition, correct the density (and volume) to an alternate temperature and pressure condition. Type 2. Starting wit
49、h an observed density at its temperature and pressure, correct the density (and volume) back to the 60F and 0 psig base condition. Type 3. Starting with an observed density at its temperature and pressure, correct the density (and volume) to an alternate temperature and pressure condition. A Type 1 calculation is straightforward starting with the density at 60F and 0 psig all parameters can be determined and the calculations can proceed in a “feed-forward” manner
