2V. -734

NBSIR 80-1626 ^

MAR t ' 1986

LIQUEFIED NATURAL GAS RESEARCH

at the

NATIONAL BUREAU OF STANDARDS

PROGRESS REPORT FOR THE PERIOD

1 JULY - 31 DECEMBER, 1979

THERMOPHYSICAL PROPERTIES DIVISION, NATIONAL ENGINEERING LABORATORY,

NATIONAL BUREAU OF STANDARDS, BOULDER, COLORADO

NBSIR 80-1626

LIQUEFIED NATURAL GAS RESEARCH

NATIONAL BUREAU OF STANDARDS

Thermophysical Properties Division

National Engineering Laboratory

National Bureau of Standards

Boulder, Colorado 80303

Progress Report for the Period

1 July - 31 December, 1979

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutzmck, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

at the

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
Prepared for:

American Gas Association, Inc.

1515 Wilson Boulevard

Arlington, Virginia 22209

LNG Density Project Steering Committee

(in cooperation with the American Gas Association, Inc.)

Pipeline Research Committee

(American Gas Association, Inc.)

1515 Wilson Boulevard

Arlington, Virginia 22209

Gas Research Institute

10 West 35th Street

Chicago, Illinois 60616

U. S. Department of Commerce

Maritime Administration

Washington, DC 20235

U. S. Department of Commerce

National Bureau of Standards

National Engineering Laboratory

Boulder, Colorado 80303

U. S. Department of Commerce

National Bureau of Standards

Office of Standard Reference Data

Washington, DC 20234

U. S. Department of Commerce

National Bureau of Standards

Office of International Standards

Washington, DC 20234

LNG Custody Transfer Measurements Supervisory Committee

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135
ABSTRACT

The objective of this report is to:

1. provide all sponsoring agencies with a semiannual report on the

activities of their individual programs;

2. inform all sponsoring agencies on related research being conducted

at the NBS-NEL Themophysical Properties Division, NBS-NEL Mechanical

Processes Division and NBS-NML Fracture and Deformation Division;

3. provide a uniform reporting procedure which should maintain and

improve communication while minimizing the time, effort and

paperwork at the cost center level.

The work is supported by NBS and seven other agencies and represents the

collective expenditure of $676,900 during the 6-month reporting period. The

contents of this report augment quarterly progress meetings for certain of our sponsors and provide a perspective which is missing when the parts are viewed individually. Distribution of this document is limited and intended

primarily for the supporting agencies. Data or other information must be

considered preliminary, subject to change and unpublished, and therefore not

for citation in the open literature .

Key words: Cryogenics; liquefied natural gas; measurement; methane;

properties; research.
CONTENTS

Cost Center

I . REFERENCE DATA

a) THERMOPHYSICAL PROPERTIES DATA FOR PURE 7360574,

COMPONENTS AND MIXTURES OF LNG COMPONENTS 7360548

(Gas Research Institute; NASA Lewis Research

Center

)

b) FLUID TRANSPORT PROPERTIES 7362290

(NBS-Office of Standard Reference Data) 7362291

7360125

C) PROPERTIES OF CRYOGENIC FLUIDS (NBS

)

7360122

7360124

7360125

d) PROPERTIES OF CRYOGENIC FLUID MIXTURES

(NBS; NBS-Office of Standard Reference

Data; Gas Research Institute)

7360123,

7362290

,

7368574

e) DENSITIES OF LIQUEFIED NATURAL GAS MIXTURES 7361574

(LNG Density Project Steering Committee - AGA)

f) MATERIALS FOR LNG APPLICATIONS (Gas

Research Institute)

7363574

g) LNG MATERIALS RESEARCH, CONCRETES

(Maritime Administration)

II. MEASUREMENT SCIENCE

7360403,

6521511

a) CUSTODY TRANSFER - LNG SHIPS (Maritime

Administration; LNG Custody Transfer

Measurements Supervisory committee)

7360460,

7361575,

7362575,

7363575,

7311573

b) HEATING VALUE OF FLOWING LNG (Pipeline 7362570

Research Committee - AGA)

c) LARGE SCALE LNG MEASUREMENTS (Pipeline 7360570

Research Committee)

d) LNG DENSITY REFERENCE SYSTEM (American Gas 7367574

Association, Inc.; Gas Research Institute)

e) BASIC NATURAL GAS METERING (American Gas 7360571

Association, Inc.; Gas Research Institute) 7362571

III. TECHNOLOGY TRANSFER

a) SURVEY OF CURRENT LITERATURE ON LNG AND 7369574

METHANE (American Gas Association, Inc.;

Gas Research Institute)

Page

1

4

6

10

13

15

18

21

22

24

25

27

42

IV
CONTENTS (continued)

b) LIQUEFIED NATURAL GAS TECHNOLOGY TRANSFER

(Maritime Administration; American Gas

Association, Inc.; Gas Research Institute;

NBS-Office of Standard Reference Data)

C) OIML JOINT SECRETARIAT ON LNG MEASUREMENTS

(American Gas Association, Inc.; NBSOffice of International Standards;

NBS-Thermophysical Properties Division)

Page

7360403,

7364574,

7368574,

7360594,

5621510

51

7360290

7460104

54

v
.
Title . THERMOPHYSICAL PROPERTIES DATA FOR PURE COMPONENTS AND MIXTURES

OF LN6 COMPONENTS

Principal Investigators . R. D. Goodwin, H. M. Roder, G. C. Straty,

W. M. Haynes, R. D. McCarty, D. E. Diller, and B. A. Younglove

Cost Center Numbers . 7360574, 7360548

Sponsor Project Identification . Gas Research Institute Grant No.

5014-361-0131. National Aeronautics and Space Administration, Lewis

Research Center,

Purchase Order C-78014-C.

Introduction . Accurate phase equilibrium, equation of state (PVT), and

thermodynamic properties data are needed to design and optimize gas

separation and liquefaction processes and equipment, and for mass and

heat transfer calculations. Accurate data for the pure components and

selected mixtures of hydrocarbon systems will permit developing

comprehensive accurate predictive calculation methods which take into

account the dependence of the thermophysical properties of mixtures on the composition, temperature, and density.

This project will provide comprehensive accurate thermophysical

properties data and predictive calculation methods for compressed and

liquefied hydrocarbon gases and their mixtures to support the

development of LNG technology at NBS and throughout the fuel gas

industry. It will also serve as the base for a comprehensive mixtures

prediction methodology.

Objectives or Goals . The objectives of our work are the determination

of comprehensive accurate thermophysical properties data and predictive

calculation methods for the major pure components (methane, ethane,

propane, butanes, and nitrogen) and selected mixtures of liquefied

natural gas and hydrocarbon mixtures at temperatures between 80 K and

320 K and at pressures up to 35 MPa (5000 psi). Our goal is to provide

a range and quality of data that will be recognized as definitive or standard for all foreseeable low temperature engineering calculations.

Background . Liquefied natural gas is expected to supply an increasing

percentage of the United States' future energy requirements. It is

likely that massive quantities of liquefied natural gas will be imported

during the years 1978 - 1990. Ships and importation terminals are being

built for transporting, storing, and vaporizing liquefied natural gas

for distribution. Accurate physical and thermodynamic properties data

for compressed and liquefied natural gas and hydrocarbon mixtures are needed to support these projects. For example, accurate compressibility

and thermodynamic properties data are needed to design and optimize

liquefaction and transport processes; accurate data for the heating

value, which for liquefied natural gas mixtures depends on the total

volume, the density, and the composition, are needed to provide a basis

for equitable custody transfer. Accurate mixture data prediction

methods are needed for use in automated heat transfer calculations.

Accurate thermodynamic properties data for liquefied gas mixtures must

be based on precise compressibility and calorimetric measurements;

compressibility data give the dependence of thermodynamic properties on pressure and density (at fixed temperatures); calorimetric data give the

dependence of thermodynamic properties on temperature (at fixed

pressures and densities). It is impossible, however, to perform enough

compressibility and calorimetric measurements directly on multicomponent

mixtures to permit accurate interpolation of the data to arbitrary

compositions, temperatures and pressures. Instead, thermodynamic

properties data for multicomponent mixtures must usually be predicted
(extrapolated) from a limited number of measurements on the pure

components and their binary mixtures. This project was initiated to

provide the natural gas and aerospace industries with comprehensive

accurate data for pure compressed and liquefied methane, the most

abundant component in LNG mixtures. We have published National Bureau

of Standards Technical Note 653, "Thermophysical Properties of Methane,

From 90 to 500 K at Pressures to 700 Bar," by Robert D. Goodwin (April

1974), and National Bureau of Standards Technical Note 684, "Thermophysical Properties of Ethane, From 90 to 600 K at Pressures to 700 Bar," by

Robert D. Goodwin, H. M. Roder, and G. C. Straty (August 1976). These

reports contain the most comprehensive and accurate tables available for

the thermophysical properties of pure gaseous and liquid methane and

ethane, and provide an accurate basis for calculating thermophysical

properties data for LNG and other hydrocarbon mixtures.

7 . Program and Results .

7.1 Propane, Isobutane, Normal Butane, PVTx and Dielectric Constant

Measurements — W. M. Haynes

PVT and dielectric constant measurements have been carried out in the

following regions for propane and isobutane:

Propane: Isotherms at 90, 100, 110, 120, 130, 140, 160, and 180 K at

pressures to 35 MPa; saturation curve at 5 K increments from 90 to 200 K and at 228.4 K Isobutane: Isotherms at 120, 140, and 160 K at pressures to 35 MPa;

saturation curve at 5 K increments from 115 to 200 K and at 228.4 K.

7.2 Calculational Methods -- R. D. McCarty

As was mentioned in the last report, the work on the extension and

optimization of the corresponding states method for the calculation of

the thermodynamic properties of mixtures has been the subject for a Master's thesis at the University of Colorado. This particular phase of

the study is now complete, but copies of the resulting thesis are still

not available. Since the completion of the above mentioned graduate

work, very little work has been done on the subject of calculational

methods, however, work on the extended corresponding states method will resume in the near future.

7.3 Propane, Specific Heat Data -- R. D. Goodwin

This project is complete and the results published in "Specific Heats of

Saturated and Compressed Liquid Propane," by R. D. Goodwin, J. Res. Nat.

Bur. Stand. (U.S.) 8_3, 449-58 (Sep-Oct 1978).

7.4 Normal and Isobutane, Thermophysical Properties -- R. D. Goodwin

Interagency reports have been printed, as follows:

NBSIR 79-1612, Isobutane: Provisional Thermodynamic Functions from

114 to 700 K at Pressures to 700 Bar, R. D. Goodwin, July, 1979.

NBSIR 79-1621, Normal Butane: Provisional Thermodynamic Functions

from 135 to 700 K at Pressures to 700 Bar, R. D. Goodwin, September,

1979.

For each substance, PVT data are lacking at temperatures roughly below

the normal boiling point (NBP) but accurate densities for the saturated

liquid are available down to the triple point.

2
Specific heats for ideal gas states and for the saturated liquid below

the NBP were combined with the experimental heat of vaporization at the

NBP , and a virial equation to derive new data from the triple to the NBP

for saturated vapor densities, vapor pressures, and for heats of

vaporization

•

By use of these data with the highly-constrained, nonanalytic equation

of state, a thermodynamic network was derived for all fluid states at

temperatures above the triple point.

7.5 Nitrogen and Nitrogen-Methane Mixtures, PVTx Property Measurements — G. C. Straty and D. E. Diller

All planned measurements and data analysis have been completed. A

report, PVT Properties of Saturated and Compressed Fluid Nitrogen, has

been submitted to the Journal of Chemical Thermodynamics for

publication. A second report, PVT Properties of Compressed and

Liquefied Nitrogen-Methane Mixtures, has also been submitted to the

Journal of Chemical Thermodynamics for publication. A poster paper

entitled PVTx Properties and Equation of State for Compressed and

Liquefied Nitrogen-Methane Mixtures is being prepared for presentation

to the 2nd International Conference on Phase Equilibria and Fluid

Properties in the Chemical Industry, Berlin, Germany, March 17-21, 1980.

7.6 Sound Velocity of Propane -- B. A. Younglove

All measurements are now complete. This includes sound velocity,

temperature, and pressure measurements on isotherms at 90, 100, 110,

120, 140, 160, 180, 200, 220, 240, 260, 280, and 300 K to a maximum

pressure of about 5000 psia (34.7 MPa). The isotherms extrapolate well

to the values measured at saturation which were mentioned in the

previous report. The results are now being written up for publication.

8. Problem Areas . None.

9. Level of Effort . July 1 - December 31, 1979.

Staff-years expended 1.0

Equipment and/or Services Purchased 12.5K$

Approximate expenditures, total 77.6K$

10. Future Plans . Quarter

Objectives and Schedule; 1 | 2 Optimize existing calculation methods for

the thermodynamic properties of methanenitrogen mixtures and LNG mixtures.

Measure, analyze and report PVT and

dielectric constant data for propane.

Publish experimental sound velocity

data for propane.

Measure, analyze, and report PVT and

dielectric constant data for isobutane

Measure, analyze, and report PVT and dielectric constant data for normal butane.

Prepare and publish Standard Reference

Data and final equations of state for

propane thermodynamic properties.

3
1 . Title . FLUID TRANSPORT PROPERTIES

Principal Investigator . Howard J. M . Hanley

2. Cost Center Number . 7362290, 7362291, 7360125

3. Sponsor Project Identification . NBS-Office of Standard Reference Data

4. Introduction . Methods for predicting the transport properties of fluid

mixtures are unreliable and data are scarce. Prediction methods are needed, however, to supply the necessary design data needed to increase

efficiency and reduce costs.

5. Objectives or Goals . The long range or continuing goal of the program

is to perform a systematic study of the theories and experimental

measurements relating to transport properties, specifically the

viscosity and thermal conductivity coefficients, of simple mixtures over

a wide range of experimental conditions. The specific objectives of the

program includes 1) the systematic correlation of the transport

properties of simple binary mixtures and the development of prediction

techniques, 2) development of a mixture theory for the dilute gas region

and the dense gas and liquid regions, 3) extension of the theory and

prediction techniques to multicomponent systems, and 4) investigation of

the properties and structure of fluids via computer similarities.

6 . Background . A continuing program has successfully expanded the stateof-the-art of transport phenomena for pure fluids. Information for pure

fluids is required as a prerequisite for mixture studies. The theory of

transport phenomena has been developed and applied to produce practical

numerical tables of the viscosity, thermal conductivity and diffusion

coefficients of simple fluids: Ar, Kr, Xe, N^f 0 F 2' He ' CH^^

C

2 H6

' (3)

C

3 H 8‘

(4)

It has been shown that a successful mixture program can emerge from

combining the results for pure fluids with mixture equation of state

studies. The equation of state work is being carried out by other

investigators in this laboratory.

7. Program and Results . A correlation of the properties of ethylene (4)

and hydrogen ( ^ ) is in the manuscript stage. Significant results

from computer similarities relating to the structure of mixtures have

been reported . (&) our computer program to predict the transport

properties of fluids and mixtures to include hydrocarbons to C 20 is near completion.

8. Problem Areas . The lack of suitable experimental mixture transport

properties data for comparison purposes remains a problem. Also

equation of state (PVT) data for mixtures are needed. Recent measurements on the methane-nitrogen system will help alleviate the problem.

(See 7.5 Thermophysical Properties Data for Pure Components and Mixtures

of LNG Components.)

9. Level of Effort . July 1 - December 31, 1979.

Staff-years expended 0.5

Equipment and/or Services Purchased 21.4K$

Approximate expenditures, total 60.0K$

4
10. Future Plans . The thrust of the effort for the next several months will

be to extend the computer simulation studies of mixtures. The studies

will yield information on the structure of the mixtures which will, in

time, lead to better methods to predict their properties.

References

1. H. J. M. Hanley, Prediction of the Viscosity and Thermal Conductivity

Coefficients of Mixtures, Cryogenics, Vol 16, No. 11, 643-51 (Nov 1976);

H. J. M. Hanley, Prediction of the Thermal Conductivity of Fluid

Mixtures, Proceedings 7th ASME Conf. on Thermophysical Properties;

H. J. M. Hanley in "Phase Equilibria and Fluid Properties in the

Chemical Industry," ACS Symp. Series No. 60 (1977).

2. B. J. Ackerson and H. J. M. Hanley (in preparation).

3. H. J. M. Hanley, W. M. Haynes and R. D. McCarty, The Viscosity and

Thermal Conductivity Coefficients for Dense Gaseous and Liquid Methane,

J. Phys. Chem. Ref. Data, Vol 6, No. 2, 597-609 (1977).

4. H. J. M. Hanley, K. E. Gubbins and S. Murad, A Correlation of the

Existing Viscosity and Thermal Conductivity Coefficients of Gaseous and

Liquid Ethane, J. Phys. Chem. Ref. Data, Vol 6, No. 4, 1167 (1977).

5. H. J. M. Hanley, P. M. Holland, K. E. Gubbins and J. M. Haile, J. Phys.

Chem. Ref. Data 8, 559 (1979 ).

6. P. M. Holland and H. J. M. Hanley (in preparation).

7. L. Van Poolen, R. D. McCarty and H. J. M. Hanley (in preparation).

8. D. J. Evans and H. J. M. Hanley, Phys. Rev. A (1979) (in press).

5
1 . Title . PROPERTIES OF CRYOGENIC FLUIDS

Principal Investigators . G. C. Straty, N. A. Olien, B. A. Younglove,

H. M. Roder, D. E. Diller, and J. F. Ely

2. Cost Center Numbers . 7360122, 7360124, 7360125

3. Sponsor Project Identification . NBS

4. Introduction . Accurate thermophysical properties data and predictive

calculation methods for cryogenic fluids are needed to support advanced

cryogenic technology projects. For example, liquefied natural gas is

expected to supply an increasing percentage of the United States' energy

requirements through 1990. Liquefaction plants, ships and receiving

terminals are being constructed to transport and store natural gas in

the liquid state ( LNG ) . Accurate thermophysical properties data for LNG are needed to design low temperature processes and equipment. Accurate

data will benefit the energy industries and the consumer by providing

for safe and efficient operations and reduced costs. We are now examining the data needs of a number of higher temperature industries

such as the synthetic natural gas ( SNG ) industry. This area of

technology as well as the liquefied petroleum gas (LPG) industry are logical extensions of the current LNG work. SNG mixtures can be

characterized as much more complex than natural gas, containing unlike

(including highly polar) molecules. Interactions between unlike

molecules are not well understood and the accurate data necessary to

quantitatively understand the interactions are lacking. The needs for

accurate predictive methods for SNG are essentially the same as LNG,

i.e., to reduce capital and operating costs and improve energy

efficiency.

5. Objectives or Goals . The objectives of this project are to provide

comprehensive accurate thermodynamic, electromagnetic and transport

properties data and calculation methods for technically important

compressed and liquefied gases (helium, hydrogen, oxygen, nitrogen,

methane, ethane, etc.) at low temperatures. In addition we intend to

develop the capability to perform accurate PVT measurements on gaseous

mixtures and pure components at high pressures and above room

temperature. Precise compressibility, calorimetric and other physical

property measurements will be performed to fill gaps and reconcile

inconsistencies. Definitive interpolation functions, computer programs

and tables will be prepared for engineering calculations. The immediate

goals of this work are to obtain accurate sound velocity and thermal

diffusivity data for compressed and liquefied gases by using laser light

scattering spectroscopy techniques; design, construct and performance

test a precision PVT apparatus for the region 250 - 900 K with pressures

to 35 MPa; and design, construct and performance test a transient

hot-wire thermal conductivity apparatus for the region 70 - 350 K with

pressures to 80 MPa.

6. Background . The application of laser light scattering techniques to

obtaining thermophysical properties data was initiated to complement and

check other measurement methods and to solve measurement problems

inherent in more conventional methods. For example, laser light

scattering techniques permit measurements of sound velocities for fluids

under conditions for which sound absorption is too large to perform

ultrasonic measurements; laser light scattering techniques permit

measurements of thermal dif fusivities under conditions for which

convection interferes with measurements of thermal conduction. The

feasibility of light scattering experiments to obtain data on binary

diffusion coefficients has also been demonstrated.

6
Light scattering allows thermal diffusivity measurements in the region

where density fluctuations are relatively large, but accuracy drops

significantly as you pass outside the extended critical region. To

complement the scattering method, thermal conductivity measurements can

be made with more conventional techniques such as a hot-wire technique.

In the latter method a very small platinum wire is surrounded by the

fluid and a voltage pulse is applied to the wire. The temperature of

the wire is momentarily raised and the resistance increases. A series

of very closely spaced resistance measurements would describe the return

of the wire to equilibrium. These resistance vs. time measurements can

be related to the rate of heat dissipation in the surrounding fluid and

thus the thermal conductivity (provided convection heat transfer is

prevented )

.

The development of accurate mathematical models (equation of state) for

fluid mixtures requires accurate PVT data for the pure constituents and

binary mixtures of key molecular pairs. Experience with LNG has

identified the type and accuracy of the data required. In addition to

that, work on SNG at high temperatures is a logical follow-on to the low

temperature work on LNG. Typical constituents of raw SNG from coal via

the Lurgi process are: water - 50.2%; hydrogen - 20.1%; carbon

dioxide - 14.7%; carbon monoxide - 9.2%; methane - 4.7%; ethane - 0.5%;

hydrogen sulfide and others - 0.6%.

An apparatus has been assembled for laser light scattering spectroscopy

measurements on compressed and liquefied gases (76 - 300 K, 35 MPa).

The apparatus consists of a high pressure optical cell, a cryostat

refrigerated by means of liquid nitrogen, an argon ion laser and

low-level light detection equipment.

The light scattered from fluctuations in the fluid can be analyzed with

either digital autocorrelation techniques for the examination of the

very narrow lines associated with scattering from temperature

fluctuations (Rayleigh scattering) or with a scanned Fabry Perot

interferometer for the measurement of the Doppler frequency shifts

associated with the scattering from propagating density (pressure)

fluctuations (Brillouin scattering).

Apparatus for photon-counting and digital autocorrelation has been

assembled, interfaced with computer facilities and programmed to enable

on-line data accumulation and analysis. Initial problems associated

with signal modulations from excessive building vibrations have been

solved by levitating the apparatus on an air suspension system. A

small, highly stable capacitor has also been designed, constructed and

installed inside the scattering cell to permit the dielectric constant

of the scattering fluid to be determined, which should allow more accurate fluid densities to be obtained for use in the data analysis.

Apparatus tests on well characterized, strongly scattering, test fluids

have been made to verify data analysis programs.

Extensive thermal diffusivity data have been obtained for methane.

Measurements have been made along the coexistence curve, the critical

isochore, and critical isotherm. The measurements extend outside the

critical region as well as deep into the critical region. In the deep

critical region the effect of temperature gradients and impurities have

been investigated. Outside the critical region, these effects do not

affect measurements beyond experimental accuracy. The range of the

measurements extends from 150 K to 230 K and 3 mol/L to 22 mol/L. The

inaccuracy of the measurements is about 5% in the critical region,

increasing to 10% or greater further away. A detailed analysis of the

data and experimental error has been made and a paper reporting

the results has been submitted to the Journal of Chemical Physics.

7
Some preliminary results on a mixture of 70% methane and 30% ethane were obtained very near the vapor-liquid critical point (plait point). The

results are interesting in that the thermal conductivity of the mixture

does not exhibit a critical anomaly whereas pure methane does exhibit an anomaly in the thermal conductivity as the critical point is approached.

The anomalous behavior of pure fluids and nonanomalous behavior of mixtures is qualitatively and quantitatively in agreement with theoretical

predictions (see preceding title "Fluid Transport Properties'). We hope

to be able to perform more definitive measurements on hydrocarbon mixtures in the near future.

7 . Program and Results.

7.1

Transient Hot-Wire Apparatus - H. R. Roder. The thermal conductivity system is in the final stages of debugging to define both accuracy

and precision of our experimental measurements. Preliminary results on oxygen encompass isotherms at 294 and 307 K from 0.4 to 60 MPa covering a density range up to twice critical (640 kg/m^). Deviations from the

correlation of NASA SP 3071 are systematic and run from -5% at low

densities to +15% at the very highest. Experimental values by Ivanova,

et al. for temperatures between 294.8 and 306.7 K differ from the present

values by 12% at the lowest density and are less than that at the other

densities. Comparison to the highest isotherm of Ziebland and Burton at

200 K reveals similar curvatures. Ziebland and Burton's highest pressure

is 13.4 MPa which at 200 K corresponds to 438 kg/m^. Assuming exact

correspondence at zero density, the deviation between present values and

the Ziebland and Burton measurements is about 5 percent at the highest

density. The differences may arise from errors in the various

experimental systems, because the isotherms compared are not truly

isotherms, or because there exists some fine-structure in the behavior of

thermal conductivity vs. density along isotherms.

7.2

Laser Light Scattering Measurements . This project is inactive at

the present time.

7.3 High Temperature PVT Apparatus - G. C. Straty and B. A. Younglove.

Funding for this program was obtained in December 1978. Nearly all of

the required equipment for the new PVT apparatus has now been constructed

or acquired and the apparatus is being assembled. Initial temperature

run-up and apparatus check out is anticipated during the next few months

followed by some preliminary measurements, probably on methane. The com- pleted apparatus will be a semi-automated PVT data acquisition system for

measurements to pressures of 35 MPa at temperatures from room temperature

to about 1000 K. This will complement existing PVT facilities used for

measurement below room temperature.

7.4 Mixture Composition Determination Using Raman Spectroscopy - D . E

.

Diller. A joint project on in-situ mixture composition determination was

carried out while Diller was on an exchange visit with NML, NBS

,

Gaithersburg during October 1978 - June 1979. The feasibility of using

Raman spectrometry for determining the composition of mixtures of natural

gas components was examined. Raman intensity measurements were carried

out on eight, gravimetrically prepared, binary gas mixtures containing

methane, nitrogen and isobutane at ambient temperature and at pressures to

0.8 MPa. The repeatability of the molar intensity ratio, ( 12 /j 2 )/Il/Yl ) < where yg is the concentration of component 1 in the mixture, and I g is

the intensity of the related line in the mixture spectrum, was examined.

The compositions of two gravimetrically prepared

methane-nitrogen-isobutane gas mixtures were determined spectrometrically

with an estimated precision of about 0.001 in the mole fraction. Typical

differences from the gravimetric concentrations were less than 0.002 in

the mole fraction. The Raman spectrum of a gravimetrically prepared,

eight component, hydrocarbon gas mixture was obtained to show that the

Raman spectrometr ic method has potential for being applicable to natural

gas type mixtures.

8
A manuscript entitled "Composition of Mixtures of Natural Gas Components

Determined by Raman Spectroscopy" by D. E. Diller and R. F. Chang has

been prepared for submission to Applied Spectroscopy.

Equipment is being assembled to continue this work in Boulder. The

method has potential for studying multiphase, multicomponent equilibria

of extreme conditions and near the critical point of a mixture.

7.5 Methane, Viscosity Measurements - D. E. Diller. The torsional

piezoelectric crystal apparatus has been performance tested on gaseous

and liquid methane. Tests has been carried out on five isotherms at

temperatures between 100 and 300 K at pressures to 10 MPa. Differences

between the measurements and the extended corresponding states model of

H. M. A. Hanley, et al. are within experimental error. Measurements on additional isotherms and at pressures to 35 MPa are in progress. The

objective of this work is to provide accurate data for testing and

improving models for calculating the viscosity of hydrocarbon mixtures.

7.6 Prediction of Thermophysical Properties of Mixtures - J. F. Ely.

Efforts are underway to develop accurate methods of predicting

thermophysical properties of mixtures containing polar and non-polar

components. Currently, a general computer program for predicting phase

equilibria is being developed and tested for simple equation of state

models. When fully developed, this program will be used to explore a modified extended corresponding states model and the Leung-Gr if f i ths

model for phase equilibria and other thermophysical properties.

8.

Problem Areas . The measurements using the hot-wire apparatus continue

to be delayed because of experimental problems.

9.

L evel of Effort . July 1 - December 31, 1979

Staff-years expended

Equipment and/or Services Purchased

Approximate expenditures, total

10

.

Future Plans . Objectives and Schedule:

Complete performance test transient

hot-wire thermal conductivity apparatus

Design, construct and performance test high

temperature-high pressure PVT apparatus.

2.2

21. 0K$

176 .0K$

Quarter

1 I 2

Measure, analyze and report viscosity data

for methane in compressed liquid and

gas region.

Complete computer program for predicting

mixture phase equilibrium.

Develop accurate model for thermophysical

properties of polar-nonpolar mixtures.

References

1. B. J. Ackerson and G. C. Straty, Rayleigh Scattering from Methane, J. Chem. Phys. 69, 1207-12 (Aug 1978).

2. B. J. Ackerson and H. J. M. Hanley, The Thermal Diffusivity of Methane

in the Critical Region, Chem. Phys. Lett. 5J3 , 596-8 (Feb 1978).

9
1 . Title. PROPERTIES OF CRYOGENIC FLUID MIXTURES

Principal Investigators . M. J. Hiza , A. J. Kidnay (part-time), R. C.

Miller (part-time), and E. D. Sloan (part-time)

2. Cost Center Numbers . 7360123, 7362290, 7368574

3. Sponsor Project Identification . NBS, NBS (OSRD), Gas Research Institute

gra-nt No. 5014-361-0131

4. Introduction . Accurate thermodynamic properties data and prediction

methods for mixtures of cryogenic fluids are needed to design and

optimize low temperature processes and equipment. This project provides

new experimental measurements on equilibrium properties and compilations

of evaluated equilibrium properties data which are suitable for direct

technological use or for the evaluation of prediction methods.

5. Objectives or Goals . The overall objectives of this project are to

provide critically evaluated data on the phase equilibria and thermodynamic properties of cryogenic fluid mixtures. The program has been

divided into the following elements:

a) Preparation of a comprehensive bibliography on experimental

measurements of equilibrium properties for mixtures of selected

molecular species of principal interest in cryogenic technology.

b) Selection and/or development of methods for correlation, evaluation

and prediction of equilibrium properties data.

c) Retrieval and evaluation of experimental data for specific mixture

systems selected on the basis of theoretical and/or technological

importance.

d) Preparation of guidelines for future research based on the

deficiencies noted in (a), (b), and (c).

e) Performing experimental research to alleviate deficiencies and

provide a basis for improvement of prediction methods.

6. Background . A physical equilibria of mixtures research project was established in the Thermophysical Properties Division in 1959. The

initial effort, based on a bibliographic search and other considerations, was directed toward the acquisition of new experimental data on

the solid-vapor and liquid-vapor equilibria and physical adsorption

properties for a limited number of binary and ternary mixtures of

components with widely separated critical temperatures. Most of the

systems studied included one of the light hydrocarbon species —

methane, ethane, or ethylene (ethene) — with one of the quantum

gases — helium, hydrogen, or neon. The data for these systems led to

significant improvements in the predictions of physical adsorption

equilibrium and a correlation for the prediction of deviations from the

geometric mean rule for combining characteristic energy parameters. In

addition, significant new information was obtained for interaction third

virial coefficients which was used in a correlation by one of our consultants, J. M. Prausnitz. The approach taken in this work has been

as fundamental as possible with the intention of having an impact on a broad range of mixture problems.

Recent efforts have been directed toward problems associated with

systems containing components with overlapping liquid temperature

ranges, such as nitrogen + methane, methane + ethane, etc.

10
7. Program and Results . A summary of recent progress is as follows:

a) The paper^^ discussing compilation, evaluation, and correlation of liquid-vapor equilibria data for methane + ethane system

appeared in the Journal of Physical and Chemical Reference Data.

b) A similar paper (2) on the methane + propane system has been

accepted for publication in the same journal

c) The updated and expanded version of the bibliography^^ on equilibrium properties of fluid mixtures is now being typed. The new version will be current to January 1980, and will include

systems containing all saturated and unsaturated hydrocarbons

through C 3 , the saturated straight and branch C 4 's and C 5 's,

and water.

d) A systematic effort has just been undertaken to reexamine

consistency tests relative to each other and some new statistical

methods with the goal of determining the sufficiency of the tests

for liquid-vapor equilibria, and the extension to solid-liquid,

liquid-liquid, and possibly PVTx in general. Most probably testing

of data for nitrogen + methane mixtures will follow.

e) Experimental measurements have been completed on the system

nitrogen + ethene principally to explore the liquid-liquid-vapor

equilibrium region. In the process, some measurements were made in

the nitrogen + ethane system as well. Measurements were made at

NBS by a graduate student/guest worker from the Colorado School of

Mines. A paper on this work is in preparation.

8 . Problem Areas. None

9. Level of Effort . July 1 - December 31, 1979

Staff-years expended

Equipment and/or Services Purchased

Approximate expenditures, total

10 . Future Plans . Objectives and Schedule:

1.4

15 . 0K$

112. 0K$ (13.5 K$ - GRI)

Quarter

I I 2 Complete preparation of updated and

expanded bibliography on equilibrium

properties of fluid mixtures

Continue systematic study of consistency

test, apply to data for nitrogen + methane

.

Complete paper on liquid-liquid-vapor

experimental data for nitrogen + ethene and nitrogen + ethane

References

1. M. J. Hiza, R. C. Miller, and A. J. Kidnay, A Review, Evaluation, and

Correlation of the Phase Equilibria, Heat of Mixing, and Change in

Volume on Mixing for Liquid Mixtures of Methane + Ethane. J. Phys. Chem.

Ref. Data, 8 , No. 3, 799-816 (1979).

11
2. R. C . Miller, A. J. Kidnay, and M. J. Hiza, A Review, Evaluation, and

Correlation of the Phase Equilibria, Heat of Mixing, and Change in

Volume on Mixing for Liquid Mixtures of Methane + Propane, J. Phys.

Chem. Ref. Data (to be published).

3. M. J. Hiza, A. J. Kidnay, and R. C. Miller, Equilibrium Properties of

Fluid Mixtures - A Bibliography of Data on Fluids of Cryogenic Interest,

NSRDS Bibliographic Series, IFI/Plenum, New York, 1975.

12
1 . Title . DENSITIES OF LIQUEFIED NATURAL GAS MIXTURES

Principal Investigators. W. M. Haynes, R. D. McCarty and M. J. Hiza

2. Cost Center Number . 7361574

3. Sponsor Project Identification . LNG Density Project Steering Committee;

American Gas Association, Inc., Project BR-50-11.

4. Introduction . Accurate density measurements and calculational methods

for liquefied natural gas mixtures are needed to provide a basis for

custody transfer agreements and for mass, density, and heating value

gauging throughout the fuel gas industry.

The basis for the custody transfer of natural gas is its heating value.

It is difficult to determine and agree on the heating value of extremely

large volumes of natural gas in the liquid state. For example, methods

for calculating the heating value of a liquefied natural gas mixture

require knowing its density, which in turn depends on its composition,

temperature, and pressure. As the compositions of LNG mixtures vary

considerably, depending on the sources of the gas and the processing

conditions, accurate methods are needed for calculating liquid densities

at arbitrary compositions, temperatures and pressures. The accuracy is

important because of the extremely large volumes of liquid involved.

5. Objectives or Goals . The objectives of this work are to perform

accurate (0.1%) and precise (0.02%) measurements of the densities of

saturated liquid methane, ethane, propane, butanes, nitrogen and their

mixtures mainly in the temperature range 105 - 140 K, and to test and

optimize mathematical models for calculating the densities of LNG

mixtures at arbitrary compositions and temperatures.

6. Background . This project is being carried out at NBS because of the

realization that equitable custody transfer agreements could be reached

more readily if the density measurements and the evaluation and

development of calculational methods were performed by independent

professionals.

An apparatus incorporating a magnetic suspension technique has been

developed for absolute density measurements on liquids and liquid

mixtures, particularly at saturation, for temperatures between 90 and

300 K. The estimated imprecision of measurement is less than 0.02% and

the estimated inaccuracy is less than 0.15%.

7 . Program and Results .

7.1 Measurements . All measurements for this project have been

completed. The last series of measurements included the following:

(a) two methane-rich binary mixtures of CH4 and iC^iQ' (b) four

methane-rich binary mixtures of CH4 and nC 4 HiO/ and (c) seventeen

methane-rich multicomponent mixtures of LNG components, including five

7- and 8-component mixtures containing up to 0.44% pentanes. The data

have been analyzed and comparisons of the experimental densities with

calculated values from mathematical models developed for predicting LNG

densities have been made.

Papers describing the apparatus, experimental procedures, and the data

and its analysis, from the last series of measurements are being

prepared for publication.

13
7.2 Calculational Methods . Final optimization on revision to all of

the models is now complete and two manuscripts are in preparation. The

final draft of the paper to appear in the Journal of Chemical

Thermodynamics is complete. Some changes to the manuscript need to be

made prior to sending it to the Steering Committee for final review.

The preparation of the NBS document which will contain computer code and

detailed instructions on their use is in progress.

8. Problem Areas . None

9. Level of Effort . July 1 - December 31, 1979

Staff-years expended None

Equipment and/or Services Purchased

Approximate expenditures, total

10. Future Plans . This program is complete apart from the publication of

the final results. There are three experimental papers in preparation,

an apparatus paper, a paper detailing the performance of the predictive

models and a final report encompassing all results of this six year

project

.

14
1 . Title . MATERIALS for lng applications

Principal Investigators . L. L. Sparks

2. Cost Center Number . 7363574

3. Sponsor Project Identification. Gas Research Institute Grant Number

5014-361-0131.

4. Introduction . Safe, economical storage and transportation of LNG

depend to a large extend on the materials used in the construction of

capital equipment, i.e., ships, storage facilities, transfer terminals,

liquefiers, and pipelines. Thermal insulations constitute a critical

link in the materials for use in LNG oriented energy efforts because of

the cryogenic nature of the liquid.

Expanded plastics (foams) are being used or are being considered for use

in facilities such as these. Low-temperature properties data,

standardized cryogenic test methods, and standard reference materials

are not presently adequate to meet the needs of complicated insulation

systems. These materials are anisotropic for most properties so that

properties data must be accompanied by specimen characterization in

order to be of general use. Standard reference materials, for use in

checking experimental systems are completely lacking. With the exception of thermal conductivity, standardized test methods for lowtemperature testing of foams are also completely lacking.

5. Objectives or Goals . The broad objectives of this project are twofold:

first, provide the users of thermally insulating foams with basic

knowledge about the behavior of expanded plastics at cryogenic temperatures and methodology to allow experimental determination of the properties of specific materials; second, serve as a center of insulation

material information for GRI and associated users of cryogenic fuels.

The first objective will be achieved by determining the low-temperature

thermal and mechanical properties of selected, well characterized foams.

The methodology of testing at low temperatures and characterizing the

test materials will be stressed. The second objective will result as a consequence of this research effort.

6.

Background . The Thermophysical Properties Division, previously known as the Cryogenics Division, has been involved in the development and

application of cryogenic insulations since being established in 1951.

The Properties of Solids group at Boulder has successfully examined the

thermal and mechanical properties of a wide variety of materials:

metals, polymers, insulations, and composites. The group, as a whole,

has the equipment and expertise to establish and perform cryogenic tests

to determine the mechanical and thermal properties of foams. Close

working relationships with private companies, universities, and

professional associations provide guidance in the areas of material

selection, quality control, and standardization of materials and

methods

.

The groundwork for the current foams research was done while working on the Insulation Section of the LNG Materials Handbook (funded by Maritime

Administration)

.

15
7. Program and Results . The program designed to meet the need for lowtemperature data and standards for expanded plastics includes the following items: assessment of materials, assessment of methods, specimen

acquisition, specimen characterization, and testing. A continuing sur- vey of the open literature and contacts with many foam related companies

are being used to assess materials and methods.

The cooperation of users, producers, standardization societies, and

other government labs, is extremely important to the success of the program. It is being stressed, particularly with the producers, that this

program is not intended to do their research for them; our results will

be related to identifiable characteristics such as general type of foam,

cell size, membrane thickness, manufacturing process, etc. Property

dependence on these parameters can be related to new as well as existing

products. Cooperation with users of foam insulations benefits the program by increasing our knowledge of practical, field-type problems.

All program areas mentioned above (assessment of materials and methods,

specimen acquisition, specimen characterization, and testing) have shown

progress during this reporting period:

Assessment of materials and specimen acquisition. Commercially produced

foams and their applicability as low temperature insulations have been

screened using information from company literature and technical

reports. The material chosen for initial testing and characterization

was a 32 kg/m^ polyurethane foam supplied by the Office of Standard

Reference Materials of NBS . Specific information on chemistry, process,

etc. for this material is being sought through the Products Research

Committee. Other materials for our evaluation are being obtained from a shipyard and an aeroscape company. The cooperation of several

commercial foam producers has been assured and will allow us to obtain

materials on request. Since many of the properties in question are somewhat time dependent, specimens will not be stockpiled, but rather

obtained as near to the time of use as practical.

Test Methods. All procedures for mechanical and thermal testing have

been outlined. These procedures are based on experience, existing standards for similar tests at room temperature, and discussions with numerous testing facilities. Continuous evaluation and refinement of our procedures may lead to extensions and modifications of existing standardized methods to include the cryogenic temperature range. Specifically, all mechanical tests will be done using capacitance gauge techniques, controllable testing environment, and programmable loading

machines. Thermal contraction, AL/L, of large inhomogeneous specimens

will be accomplished utilizing a recently completed system designed for

this purpose. This system also includes an environmentally controllable

test space. The contraction will be measured relative to a copper

reference standard by deflection of an incident laser beam. This system

was chosen because, in addition to allowing accurate yet simple measurements, it avoids the necessity of attaching a length or strain measuring

device to the specimen. For lightweight foams the results are influenced by the mechanical constraints imposed by these devices. Thermal

conductivity in the temperature range 76 £ T _< 373 K was determined

using an ASTM sanctioned guarded hot plate system.

Specimen Characterization. This area has been emphasized during this

period. A technique utilizing a metallographic microscope for determining cell size and orientation has been developed. The foam stock

being used for the initial specimens has been thoroughly examined with

respect to the morphology of the material. We are now in the process of

evaluating reproducibility and observer influence. Microphotographs

16
necessary to do an extensive cell size and shape study have been made.

Cell-gas constituents have been determined using the mass spectrograph

facility at a nearby industrial plant. This cooperative venture

involved constructing a system which could be used to free the cellular

gas, could be transported between labs without contaminating the gas

specimen, and could be integrated into the Rockwell systems. The work

to date has been free to NBS since it was of an exploratory nature:

subsequent work in this area will be on a contract basis.

Testing. Thermal conductivity of a hydrocarbon filled 32 kg/m^ polyurethane foam has been determined in the temperature range 76 < T < 373 K.

Computer programs necessary to analyze the data have been developed, and

final results are imminent.

8. Problem Areas . None.

9. Level of Effort . July 1 - December 31, 1979

Staff years expended 0.74

Equipment and/or Services purchased $ 2,617

Appropriate Expenditures, Total $60,300

10. Future Plans . During the next reporting period we will complete the

thermal and mechanical testing programs for the material now being con- sidered. We will also refine our cellular study techniques and expand

our analysis capability in this area. A crucial phase of the program,

relating observed cryogenic properties to foam structure, chemistry, and

processes, will begin. Thermal contraction, L/L, is extremely important in applications involving insulating foams, and measurement of this

property will be stressed. L/L for additional specimens will be determined as possible. Our cooperation with other government agencies and

industrial users of foams will continue and expand as relevant opportunities come to our attention.

17
1 . Title . LNG materials research, concretes

Principal Investigators . L. L. Sparks and J. M. Arvidson

2. Cost Center Number . 7361403, 5621511

3. Sponsor Project Identification . Maritime Administration, Miscellaneous

Purchasing Order No. 400-89019.

4. Introduction . Concretes are attractive materials for construction of

large LNG installations because of lower material cost and economies of

fabrications compared to alternative construction methods. They exhibit

favorable mechanical and thermal properties for use in LNG applications.

Although these materials are presently used to some extent in LNG con- struction, lack of confidence in their cryogenic behavior has restricted

their use to noncritical components or has resulted in overly conservative and expensive designs. This reflects the lack of dependable cryogenic thermal and mechanical properties data and a poor understanding of

the effect of field fabrication variables on cryogenic performance.

Applications of special concretes such as lightweight, cellular, fiber

reinforced, and polymer will depend on their cryogenic properties, which

are unknown at this time. The experimental program to determine these

properties will be executed in cooperation with the USCG, Portland

Cement Association (PCA), and several private corporations.

5. Objectives or Goals . The program objectives are to determine the low

temperature (76K T _< 300K) properties of concretes which are presently

being used in LNG applications and those which may provide design alternatives in the future. The properties which may be determined include:

thermal conductivity. Young's modulus, thermal expansion, compressive

strength, fatigue strength, splitting strength, permeability to water

and LNG, and thermal shock. The dependence of these properties on parameters such as moisture content, air content, water- to-cement ratio,

additives, aggregate type and grade, and aging will be determined. The

parameter dependencies will be studied in order to understand the fundamental basis for the cause/effect relationships which are observed.

Specimen characterization and parameter control are extremely important

to this phase of the program. Knowledge gained from the parameter

dependencies will be used to assess variabilities found in field-erected

structures. This information is needed to establish the quality control

necessary to assure f itness-for-service in cryogenic applications. The

testing procedures which are used must produce reproducible and accurate

data. With the exception of thermal conductivity tests, there are no standardized procedures for testing concretes at cryogenic temperatures.

The large variations found in the literature are due, in part, to this

deficiency. Whenever possible, ASTM , and ACI procedures, modified to

accommodate the cryogenic environment, will be used throughout this program.

6. Background . The initial involvement of the Cryogenics Division in the use of concretes as low temperature structural materials was in 1973.

Safety aspects of concrete, in cryogenic installations were stressed.

Data from the literature were collected and used in these safety evaluations; it became very clear that reliable cryogenic data, basic

cause/effect relationships, and standardized cryogenic experimental procedures were inadequate. The situation has not changed significantly.

18
as was determined in a thorough literature evaluation of concrete at

cryogenic temperatures ( LNG Materials Handbook, second supplement,

funded by MarAd )

.

The Properties of Solids group at NBS-Boulder has successfully examined

the thermal and mechanical properties of a wide variety of materials:

metals, polymers, insulations, and composites. The group, as a whole,

has the equipment and expertise to perform cryogenic tests to determine

the mechanical and thermal properties of concretes. Close working

relationships with private companies, universities, and professional

associations provide guidance in the areas of material selection and

quality control of field-erected structures.

7. Program and Results . The extended program calls for establishment of an understanding of the low-temperature behavior observed for two different, "ordinary" concretes (portland cement, sand and gravel aggregates).

This understanding must include the effects of parameters such as moisture and air content, water to cement ratio, additives, aggregate type

and size, and age. Properties to be used in this study include thermal

conductivity and contraction, and the strengths and moduli. Field

poured concrete and alternate types of concrete will be studied using

the procedures and understanding developed for ordinary concretes.

The compressive strength of the initial, well characterized concrete mix

has been determined in the temperature range 76 <_ T _< 300K. Test temperatures were 295, 195, and 76K; four specimens were used at 195 and

76K and three were used at 295K. The specimens contained approximately

8% free water and the compressive strength increased by 400% when

cooled from 295 to 76K. Modulus data were also obtained from these

tests and from an additional test at 4K.

8. Problem Areas . None.

9. Level of Effort . July 1 - December 31, 1979

Staff years expended 0.35

Equipment and/or services purchased $ 2,617

Approximate Expenditures, Total $30,000

10. Future Plans . Thermal and mechanical properties of the well characterized concrete mix, tested in compression in the 1979 program, will be

completed in the temperature range 76 _< T _< 300K. The specific properties which remain to be determined are thermal conductivity, thermal

contraction (AL/L), flexural strength, and splitting strength. These

properties plus compressive strength will also be determined for a second, different concrete mix. This testing program involves a large num- ber of individual tests, since multiple (a minimum of three) specimens

are required at each temperature for each test. Knowledge of specimen

variability obtained from these multiple tests is an essential part of

the basic property data for concrete specimens.

The apparatus to be used in determining AL/L for large, inhomogeneous

specimens such as concrete has been completed. In view of the lack of

reliable data for this important design property, these measurements

will be stressed; it is tentatively planned to study this property for

other concretes in addition to the two mixes discussed above.

Characterization of specimens, which includes obtaining detailed information of moisture content, aggregate type and distribution, air content, porosity, and chemical composition of the cement, will be required

for each type of specimen. Methods for accurately determining these

19
characteristics

be developed or are essentially

and for testing

refined in this

nonexistent for

concretes in cryogenic environments will

phase. Standardized testing procedures

concrete at low temperatures.

In addition to producing much needed low- temperature data for concrete,

the proposed 1980 program will provide the groundwork for the very

important parameter variability study anticipated in 1981. Established

test method and characterization procedures are prerequisites for determining effects of parameters such as aggregate variability, moisture

content, air content, void density, and cement composition on the thermal and mechanical properties. The results of the 1980 effort will be

published in the open literature and presented at appropriate technical

meetings

.

20
1. Title . CUSTODY TRANSFER - LNG SHIPS

Principal Investigators . W. C. Haight, R. J. Hocken, B. R. Borchardt,

R. G. Hartsock, R. C. Veale, J. D. Siegwarth, J. F. LaBrecque, C. L. Carroll, C. P. Reeve, and F. E. Scire

2. Cost Center Numbers. 7360460, 7361575, 7362575, 7363575, 7311573,

7311577

3. Sponsor Project Identification . LNG Custody Transfer Measurements

Supervisory Committee and Maritime Administration Misc. P. 0.

#400-79005.

4. Introduction . In response to the requests from the U.S. shipbuilding

industry, NBS is independently examining the accuracies of LNG tank

cargo capacity tables and developing alternative survey techniques.

5. Objectives . The objectives of the program are to develop new techniques for LNG transport tank calibration and to test the accuracy

of present calibration techniques as part of an overall study of

custody transfer methods aimed at increasing the accuracy of custody

transfer meansurements

.

6. Background . Initial funding by the Maritime Administration (7360460)

supported some preliminary tests of calibrations of spherical LNG ship

tanks. As a result of these measurements, the LNG Custody Transfer

Supervisory Committee and the Maritime Administration have funded

extension of the work to the membrane tanks and the free standing

prismatic tanks now under construction in U.S. shipyards.

7. Program . The calibration reports have been completed and issued for

all three of the membrane ships. The NBS determined volume height

relationships for these tanks agree with those determined by the

primary surveyor to better than + 0.2%.

Interim reports of analyses of the photogrammetr ic surveys are nearly

completed for the first two of the ships employing the free standing

prismatic tank design. The volume determined by the primary survey

agrees with the independent determination by NBS to better than + 0.2%.

8. Problem Areas . Completion of this work has been delayed because of

problems with the tank insulation system.

9. Level of Effort . July 1, 1979 to December 31, 1979

Staff years expended 0.2

Approximate expenditures, total 15 K$

10.

Future Plans . The interim reports for the first two ships of the free

standing tanks design will be formally issued and the interim report

for the third ship will be completed. The bottom surveys of the third

ship will be completed as soon as the tank insulation is modified. The

results of other measurements related to tank calibration accuracy will

be reported. These various reports will be combined into a final

report estimating the calibration accuracy of the cargo tanks of these

three ships.

21
1 . Title . HEATING VALUE OF FLOWING LNG

Principal Investigators . J. A. Brennan

2 . Cost Center Number . 7362570

3. Sponsor Project Identification . Pipeline Research Committee (American

Gas Association) PR-50-48.

4. Introduction . This project will test instrumentation for making heat

value measurements on flowing LNG in actual applications. Information

from projects currently underway by Siegwarth (cost center 7367574) on densimeters, by Haynes and Hiza (cost center 7361574) on mixture

densities and by Richards (cost center 7363570) on LNG sampling will be

utilized where appropriate to provide state of the art information.

5. Objectives . The objective of this project is to measure total heating

value of LNG flowing in a pipeline by the integration of individual

measurements of flow, density and specific heating value. Flow

measurement requires determination of flowmeter performance in line

sizes larger than are presently available in operating calibration

facilities. Therefore, a secondary objective is to establish

appropriate flowmeter scaling laws.

6. Background . The LNG flow facility at NBS was used to evaluate the

response and integration of the individual elements of the heating value

measurement. Different compositions of LNG were tested to provide a range of densities and temperatures sufficient to determine any

dependencies. Sampling work was combined with the sampling project

(cost center 7363570) to better define the important criteria of this

phase of the measurement problem.

Flowmeter scaling work utilizes the cryogenic and water flow facilities

at NBS as well as private LNG peak shaving and import facilities.

7. Program and Results . One additional test was run on the densimeter and

flowmeter installed at the LNG import terminal. This test was run to

check new flowmeter electronics in an effort to eliminate the occasional

poor signal quality referred to in the last report. During this test,

extended time was allotted to repeat tests using the old electronics and

well as the new. No signal quality problems occurred during any of the

testing.

There is no definite proof that the signal quality problems experienced

are electronic in nature. Since they appear randomly, it has not been

possible to do a good analysis of them. It is possible that the problem

might be caused by foreign material in the LNG interferring with the

vortex sensor. It has been difficult to isolate the problem because of

its random nature, but it will be investigated one more time in conjunction with instrumentation check out for another project. If the poor

signal quality occurs during those tests, some additional checks will be

completed in an effort to determine the source of the problem.

Densimeter tests were run each time the flowmeter was tested. After the

necessary electronic component changes were made, the densimeter ran properly for the remainder of that test run. The output followed

changes in density as calcuated from gas analysis and temperature and

pressure measurements. During the next test however, the densimeter

output was very unstable. The instability was not the same problem that

had been experienced before the electronic components were changed, but

did persist throughout the test.

22
Apparently the densimeter instability resulted from a higher flow rate.

A constant high flow rate existed during this whole test. Although the

velocities within the pipe were not excessive [ 0.3 m/s (10 ft/s)]

apparently the combination of the higher flow rate and the location of

the densimeter relative to a tee resulted in the poor performance.

Another test was run at a later time when the flow rate was lower and

the densimeter functioned properly again.

An attempt will be made to investigate the apparent flow rate dependence

on densimeter performance during the instrumentation check out run referred to above. The ability to make this test is dependent on the

gas send out rate from the terminal. Results from these tests will be

reported in project "Large Scale LNG Measurement" in the next report.

This project has been completed and a final report to sponsor is in

preparation.

8. Problem Areas . Discussed in section 7.

9. Level of Effort . July 1 - December 31, 1979

Staff years expended 0.2

Equipment and/or services purchased none Approximate Expenditures, Total $9200.00

23
1 . Title. LARGE SCALE LNG MEASUREMENTS

Principal Investigators . J. A. Brennan

2. Cost Center Number . 7360570

3. Sponsor Project Identification . Pipeline Research Committee (American

Gas Association) PR-50-104.

4. Introduction. This project is an extension of the work started on the

project "Heating Value of Flowing LNG." Flowmeter scaling work will be

extended to a line size of 32 inch (81 cm) diameter. Tank volume will

be used as the flowmeter comparison value rather than gas flow rate

values. Liquid level measurement in and volume determination of large

storage tanks will be an important element in this investigation.

Previous work on LNG densimetry will also be continued under actual LNG

terminal operations.

5. Objectives and Goals . The major objectives of this project are to

extend flowmeter scaling to larger pipe diameters, to evaluate LNG

densimetry under actual end use conditions and begin liquid level

evaluation in large land based tanks. The work will be completed at a new LNG import terminal now under construction.

6. Background . Previous work on LNG flow element investigations was limited to a maximum line size of 12 inch (30 cm). The work was completed utilizing industrial LNG peakshaving and import facilities and was related back to the NBS cryogenic flow facilities in Boulder,

Colorado, and the NBS water flow facilities in Gaithersburg, Maryland.

Extensive densimeter evaluations have also been completed at NBS-Boulder

with some additional testing at an LNG import terminal. This project

will extend the previous work to larger line sizes and also start work

on liquid level measurements in large storage tanks.

7. Program and Results . The major effort has been in selecting and

specifying instrumentation required to fulfill the project objectives.

Some preliminary testing of components in the NBS liquid nitrogen flow

facility will be completed wherever possible, but because of the size

requirements, this testing will be limited.

New recording instrumentation will be utilized on this project which

will permit on line computations to be performed. This new instrumentation will be tested and debugged at Southern Energy Company's import

terminal as soon as possible, and then it will be moved to the new import terminal.

The new recording system will permit more timely problem identification

in any of the test instruments and allow corrective measures to be

implemented. Many of the problem areas associated with the previous

projects at the LNG test sites were not identified until after the

recorded data were returned and analyzed. Obviously, this procedure can result in considerable time waste which should be eliminated with the new system.

8. Problem Areas . No major problems have been encountered. Some problems

have arisen in getting the required instrumentation modified so that it

will meet the requirements of the terminal. It is anticipated that

these problems can be favorably resolved.

9. Level of Effort . July 1 - December 31, 1979

Staff years expended .35

Equipment and/or Services Purchased none Approximate Expenditures, Total $14,500.00

24
1 Title

.

LNG DENSITY REFERENCE SYSTEM

Principal Investigators . J. D. Siegwarth and J. F. LaBrecque

2. Cost Center Number . 7367574

3. Sponsor Project Identification. Gas Research Institute, Grant No.

5014-361-0131.

4. Introduction . A density reference system has been developed to evaluate

the ability of commercially available instruments to measure densities

of LNG directly. Density is an essential measurement in determining the

total energy content of natural gas reservoirs.

5. Objectives The object of this research is to develop and supply

adequate calibration methods and calibration standards to densimeter

manufacturers and users for providing traceability of accuracy to field

density measurement systems.

6. Background . The density reference system project was initiated in 1973.

Since that time the reference system has been designed, constructed, and

is now in operation, evaluating commercial density metering systems.

Reports describing the density reference system and the results of the

tests of four commercial densimeters have been published. These reports

are:

Siegwarth, J. D. , Younglove, B. A., and LaBrecque, J. F. , Cryogenic

fluids density reference system: provisional accuracy statement,

National Bureau of Standards (U.S.) Technical Note 698, 24 pages (1977),

and

Siegwarth, J. D. , Younglove, B. A., and LaBrecque, J. F. , An evaluation

of commercial densimeters for use in LNG, National Bureau of Standards.

(U.S.) Technical Note 697, 43 pages (1977).

The work has also been presented in the following papers:

Siegwarth, J. D. , Younglove, B. A., and LaBrecque, J. F. , Test of

densimeters for use in custody transfer of LNG, Proc 53rd International

School of Hydrocarbon Measurement, Normon , Oklahoma (1978).

Parrish, W. R. , Brennan, J. A., and Siegwarth, J. D., LNG custody

transfer research at National Bureau of Standards, American Gas

Association Operating Section Proc. T243 (1978).

7. Program . The DRS densimeter using a new electronic balance has been

completed and is in operation. The shift of the density readings noted

after the DRS was rebuilt has continued supporting the earlier

assumption that the shift resulted from a balance corner loading

maladjustment in the earlier work. The reference weight is not required

for the density measurement with this new balance and thus can serve as

a monitor of the balance calibration. The DRS densimeter is now much

less sensitive to noise and the readings are more stable than with the

earlier model. A similar reference densimeter, designed after the DRS

densimeter but for use in an industrial lab, has been compared to the

DRS densimeter in the DRS. The electronic balance and the weighing

procedure differ but both use a silicon single crystal as a denisity

sensor. Simultaneous density measurements with this densimeter and the

DRS densimeter agree to better than 0.02%.

25
Measurements have been completed on four vibrating element densimeters

both for evaluation and for calibration as transfer standards. The

instrument by one manufacturer shows a velocity of sound dependence.

The densimeters by a second manufacturer seem to be stable when the

filter screens are removed and insensitive to velocity of sound or cycling. A densimeter by a third manufacturer is on hand for testing

and calibration.

A calibration method was devised for the Archimedes densimeters during

the course of tests of several of these densimeters. Three were also

tested for repeatibility after handling and all were found to be

sufficiently stable.

A portable densimeter similar to the DRS densimeter has been designed

and is under construction. This will provide a standard densimeter

based on a silicon single crystal that can be installed in other

calibration systems to test the system accuracy.

An updated accuracy report for the DRS will be issued as will a report

of recent tests of commercial densimeters.

8. Problem Areas . None

9. Level of Effort . July 1 - December 31, 1979

Staff Years Expended 0.6

Equipment and/or Services purchased $ 8,000

Approximate Expenditures $40,000

10. Future Plans . We will analyze and calibrate the vibrating plate

densimeter as a transfer standard. The portable DRS will be completed,

tested, and will be transported to other laboratories to determine

relative accuracies of calibration facilities. A comparison of the DRS

and the Gaz de France densimeter calibration system via this portable

densimeter is planned. An updated accuracy report for the DRS will be

issued as well as a report of the tests of commercial densimeters

completed since the issuance of Technote 697.

26
1 . Title . BASIC NATURAL GAS METERING

Principal Investigators . Douglas Mann, James A. Brennan, and

Clarence Kneebone

2. Cost Center Number . 7360571, 7362571

3. Sponsor Project Identification . Gas Research Institute Research Grant

No. 5014-361-0131 and American Gas Association, Inc.

| 4. Introduction . The National Bureau of Standards has under development a gas flow reference system capable of directly relating gas meter

peformance to standards of mass and time. The facility coupled with

existing liquid flow capabilities will provide a basis for significant

improvements in gas quality and quantity measurements.

The new system will provide a factor of five to ten improvement in the

total uncertainty of gas flow measurement which may be applied immediately to gas industry developed standards and codes. This could reduce

the bias within field meters of the same generic type and size or meters

of different types. The benefits are two fold; possible reduction in

unaccounted for gas and increased credibility of measurement.

Reporting progress of this project under the NBS LNG Research program

is justified by the general interst of the natural gas industry in both

liquid and gas measurement research and a direct relationship of natural

gas flow measurements to LNG flow measurements. Specifically, the

project HEATING VALUE OF FLOWING LNG (see table of contents) relies

heavily on the measurements of vaporized LNG (natural gas) to establish

accuracy and precision of the LNG flow metering.

5. Objectives and Goals . The objectives of the program are to apply the

capabilities of the new gas flow reference system to an existing well

characterized gas industry measurement problem to assess the value of

the new system in significantly improving gas flow measurements. If

successful, the program will be directed to improving gas flow measurement through upgraded existing codes and the development of necessary

data for defining new model codes and standards for gas flow

measurement.

6. Background . Natural gas is collected, transported and distributed to

industries, residences and utilities through one million miles of

pipelines and mains. Ownership changes many times as the gas is

delivered from the producer to the consumer and at each change of

ownership, the value is established by some type of measurement. The

establishment of value of natural gas in commerce as to both quantity

and quality is usually made under dynamic flow conditions.

Measurement of value is accomplished using many different types of

instruments such as positive displacement meters for small residential

users to large head type or turbine type meters in transmission lines.

Establishment and maintenance of the measurement system is a vital

element of interest to both the gas industry and the National Bureau of

Standards

.

Calibration or proving of meters can be quite simple or complex

depending on the gas flow rate, temperature, pressure, and mixture. Low

pressure, low flow rate meters may be calibrated using water displacement which is economical and can be quite accurate and precise.

Instruments for measurement of flow at several thousand cubic meters per

minute at pressures of .27 to 1.37 MPa can not be directly calibrated in

a routine manner, and therefore, infered methods must be used. These

methods currently involve construction of the meter to empirically

27
established specifications, water calibration to confirm basic meter

factors, and then modification of the meter factor to account for com- pressibility and other non-ideal properties of the fluid to be measured. Other methods of proving of high flow rate capacity meters

such as series operation with nozzles or multiple parallel meters are expensive and rely heavily on calculated performance rather than

direct experimental evidence.

Program and Results . Under previous NBS funding, the new gas flow

reference system was completed and the concept demonstrated. A description of the method and apparatus is appended to this report. In

summary, nitrogen in both liquid and gas phases is circulated in a closed loop pump system. At 0.41 MPa and 288 K, the nitrogen is

metered as a gas in the experimental gas flow test section. The

nitrogen fluid is then cooled and expanded to 0.68 MPa and 90 K where

its liquid density allows accurate and precise weight measurement.

The liquid test draft is measured in such a way as to not disturb the

steady state flow through the system. After weighing, the fluid

nitrogen is again pumped to 0.41 MPa, warmed to 288 K and circulated

through the gas meter test section.

A standard 4 inch diameter AGA- 3 orifice meter run has been installed

in the gas test section and preliminary test data indicates stable

flow rates over a range of 2900 to 9000 kg/hr nitrogen gas. Temperatures at the gas test section can be varied from 273 K to over 316 K and pressures vary from .37 to .42 MPa. Initial test data have been

taken using 3.8 cm and 5 cm (1.5 and 2 inch) gas orifice plates and

five separate runs have giving nearly 80 test points over the weight

flow range. Bore Reynolds Numbers of 4 million have been achieved and

are believe to be above values used in orifice meter correlations.

A Steering Committee was formed to aid in the planning and review of

the Basic Natural Gas Metering Program. The committee is composed of

eight natural gas industry members and the NBS staff. The committee

met at NBS Boulder in October to review progress and has been instrumental in planning tests to establish the value of this new research

tool. Future meetings are planned on a two to three a year basis.

Problem Areas . Original planning called for immediate testing of 5,

7.6 and 10 cm (2, 3, and 4 inch) orifice meter runs to develop new discharge and expansion coefficient values. This plan has been

delayed in order to define more fully the characteristics of the

system and to aid in the development of credibility of the results.

Level of Effort . October 1 - December 31, 1979

Staff-years expended 0.25

Equipment and/or services purchased $ 1,500.00

Approximate expenditures $24,000.00

Future Plans . During the next reporting period, a 10 cm (4 inch) gas

turbine meter previously calibrated on natural gas using nozzels as the proving device will be installed in series with the 10 cm (4 inch)

orifice run. Tests will be conducted to intercompare the reference

weight system, gas turbine meter and gas orifice meter. This will

provide necessary information to establish the total uncertainty of

the new gas flow reference system. As a result, an Uncertainty Statement will be issued as an NBS report which will provide the values of

total uncertainty of mass flow measurement in the gas phase and supporting data. Methods of maintaining statistical control of measurement process will also be given.

A master orifice meter test plan will be developed to allow new test

data to be accumulated on this system and other reference systems

using both liquid and gas as the test fluid. The original objective

of generating new data on orifice discharge and expansion coefficients

will be resumed after Steering Committee review.

28
ON A NEW METHOD OF GAS FLOW MEASUREMENT USING CRYOGENIC TECHNIQUES

D. B. Mann and J. A. Brennan

Cryogenics Division

Institute for Basic Standards, National Bureau of Standards

Boulder, Colorado 80302

Direct comparison of ambient temperature gas flow measurements to mass is made possible by a new continuous closed-loop

measurements method. The direct comparison is made possible by

modification of a proven flow reference system based on masstime.

The complete gas flow reference system has, as yet, not been

demonstrated physically; however, the liquefied gas portion has

been continuously proven over a period of six years and is the

flow standard for the recently developed cryogenic flowmeter

code. Modifications are state-of-the-art additions of heat

exchangers and process control. It is believed that the accuracy

of the liquid system (less than + 0.2%) will be maintained after

modification.

If implemented, the method would be extremely valuable in

improving and redefining many of the present gas flow measurements and standards. Gas and liquid meter coefficients could be

related directly to mass and to each other without the tedious

reliance on state equations and accurate pressure and temperature

measurements. The validity of liquid calibration for gas service

could be confirmed on a mass basis. Current codes and recommended

practices could be supported and improved with new, more accurate

empirical data. The method can be extended to mixtures such as natural gas and would improve the accuracy of these measurements.

It is believed that this modification is a significant and

timely improvement within measurement science which could have

major impact on custody transfer and energy conservati on.

Key words: Cryogenic; flow; gas; liquid; mass flow; measurement.

Paper presented at the 1977 NBS Flow Symposium, February 23-25, 1977, Gaithersburg, Maryland.

29
1. Introduction

A new and more accurate method of measuring gas flow in terms of mass

is possible using existing, well developed cryogenic techniques. The

method, which could be used to redefine present gas flow measurement codes

and standards, is a natural and logical development from codes and standards measurements of cryogenic liquids such as oxygen, nitrogen, argon and

hydrogen. The method is closed-looped allowing extended periods of observations at set gas pressures, temperatures and flow rates. Gas pressures

above 1000 psi and gas temperatures above ambient temperatures are possible.

The method is suitable for air, oxygen, nitrogen, argon, methane and natural

gas mixtures of methane, ethane, propane, butanes, and nitrogen, and could

be extended to neon, hydrogen, helium and other fluids.

Total uncertainty in mass flow is based on an existing cryogenic flow

reference facility having over six years of operational experience. If

successfully applied to gas flow measurements, gas flow measurements and

standards could be improved by a factor of from five to ten.

Other studies made possible with this new method are:

a) Direct comparison of gas to liquid flow on a mass basis.

b) Intercomparison of gas to water or other fluid flow on a mass

basis.

c) Performance of gas flowmeters operating on low temperature gases.

d) Investigation of Reynolds number variations at constant mass

flow.

The new method will be described in general terms with several operating modes followed by a detailed description of the existing Cryogenic

Flow Facility and modifications necessary to prove the new method.

2. Gas-Mass Flow Reference System

The system is shown in an elementary schematic in Figure 1 and thermodynamically in figure 2. The cyclic process is continuous with only power

to the pump and refrigerant to the subcooler as requi rements . Liquefied

gas subcooled under moderate pressures (0.7 MPa) is fed to the inlet of the

pressure pump 1. The pump is of the turbine type to minimize flow pulsations and capable of pressurizing the liquefied gas to above critical

pressures 4 MPa) at 2. This single phase compressed fluid is then fed

to the first pass of the counter flow regenerative type heat exchanger

where it is heated to ambient temperature or above at 3. An electric

heater is installed at this point to stabilize the gas temperatures. The

gas meter test section contains all necessary upstream and downstream flow

conditioning such as pipe length, flow straighteners , the meter and all

other standard meter run equipment. Gas leaving the gas meter test section

will be at a lower pressure (depending on the meter type) and at a different

temperature (depending on test and ambient temperatures) at 4. The gas

30
LIQUID

METER

TEST

SECTION

1 i f

z

<

£ S

“ :E * O

h-

<o

o

e

LU

_Jo

oo

CO

=3

CO

31

Figure

1.

Gas

flow

measurement

system

schematic

for

operation

at

greater

than

critical

pressures.
TEMPERATURE

Figure 2. Operation of flow measurements system at above critical pressures.

32
will then be fed to the second pass of the counter flow heat exchanger

where it leaves as a compressed fluid at cryogenic temperatures at 5. The

pressure of the fluid is reduced by a simple expansion through an expansion

valve to moderate pressures 0.7 MPa) and fed to the subcooler at 6. The

subcooler provides a controlled liquid temperature prior to the liquid

meter test section.

The liquid meter test section contains all necessary liquid flow

treatment and the cryogenic flowmeter. This meter can be of the same type

and design as the gas meter or can be a proven cryogenic meter used as a secondary standard.

After metering, the liquid enters the catch and weigh system which are

shown as concentric containers. The weigh tank is supported on a load

string and a load cell. Load cell calibration is maintained with standard

weights referenced to NBS standards of mass.

At periodic intervals the drain valve in the weigh tank is closed and

a quantity of cryogenic fluid is accumulated in the weigh tank 10. The

time required to accumulate a given weight of liquid is measured and the mass flow rate calculated. The weigh tank drain valve is then opened and

the liquid cryogen is released to the catch tank 11.

Pressures within the catch and weigh tank are maintained above the

fluid saturation pressure by inert gas pressurization to maintain subcooling

and to eliminate flashing after expansion at point 6. The actual pressure

selected will also depend on the pressure ratio available from the pressure

pump.

The schematic of figure 1 is the simplest equipment arrangement and

will allow operation of gas meters above the critical pressure and with low

pressure drop through the gas meter. These conditions can be met with

flowmeters with 100 in. water pressure loss such as orifice meters, venturi

meters, some turbine meters and most non-intrusive type flowmeters.

For operation at pressures below critical pressure, some additional

equipment must be added. Figures 3 and 4 show these modified arrangements.

In figure 3, a low-head high-volume flow circulation pump is used in

place of the pressure pump. A boiler and heat source are added to vaporize

the liquid prior to heating to ambient temperatures and a condenser is

required to reliquefy the gas prior to subcooling. This additional equipment is made necessary because the temperature of condensation of the fluid

from the gas meter test section is equal to or less than the boiling point

temperature of the fluid discharged from the circulation pump. A high

capacity blower could be installed at the outlet of the gas meter test

section to increase the pressure and therefore the saturation temperature,

but this would defeat one of the advantages of the method which is low

power requirements and simplicity.

33
LIQUID

METER

TEST

SECTION

34

SUBCOOLER

CONDENSER

I

HEATER

Figure

3.

Gas

flow

measurements

system

schematic

for

operation

at

less

than

critical

pressures.
TEMPERATURE

ENTROPY

Figure 4. Operation of flow measurements system at less than critical pressures.

35
For the special case of large meter pressure losses, such as choked

nozzle flow, a combination of the two cycles would be necessary. The pump

must be a pressure pump, as in figure 1, to provide the necessary high pressure

at the gas meter inlet; however, a condenser and heater will be necessary

as in figure 3, to provide external heating of the high pressure stream and

condensation of the low pressure stream. No pressure reducing valve would

be required.

3. Liquid Mass Flow Reference System

In the gas mass flow measurement system just described, the actual mass flow measurement takes place while the gas is in its liquid phase.

For commercial industrial gases such as oxygen, nitrogen, argon, methane

and natural gas mixtures, the liquid phase is in the cryogenic temperature

region. This is a fortunate situation because we can establish the potential

limiting accuracy of the gas mass flow system by referring to an existing

cryogenic liquid mass flow measurement system.

The cryogenic flow measurement reference system was established in

1968 in a joint government-industry program on cryogenic flowmetering.

Under that program, NBS joined with the Compressed Gas Association and

state regulatory agencies to establish a flow reference system, to evaluate

existing flowmeters used in commercial service, to evaluate new measurement

methods and to establish a national model cryogenic flow measurements code

through the National Conference on Weights and Measures. A schematic of

the facility constructed under that program is shown in figure 5. The

similarity to the previously described gas mass system is obvious. The

basic operating principles of the two systems will be very similar and the

basis for the estimate of uncertainty in mass flow measurement should be

identical

The cryogenic flow measurement program was completed in 1976 with the

acceptance of a permanent cryogenic flow measurement code by the Conference

on Weights and Measures. The description of the facility and program are

well documented in the literature (see references). The most pertinent

reference to this discussion of the gas mass flow system is the work of

Dean, et al. ( 1971 ). This report is a summary of an 18-month study to

determine the accuracy of the flow reference system, "At this time the

uncertainty of the measurement of totalized mass flow is estimated to be

+0.18%. This figure includes an uncertainty of +0.12% for known sources of

systematic errors plus an uncertainty of +0.06% for random error. The

estimated uncertainty due to the random error is three times the standard

deviation calculated from 23 applications of the calibrated masses over a period of three months." The report provides a complete description and

data on how this accuracy statement was determined and, in addition, provides a description of the process control which allows the reference

system to be kept under statistical control.

Over sixty flowmeters based on five different generic types were included

in the evaluation program. Transfer standards were developed for field

certification of commercial meters as well as being used in inter-laboratory

36
nan

nom

37

Figure

5.

Cryogenic

flow

measurements

reference

facility

schematic.
comparisons which provided additional validity to the accuracy statement.

Confidence in the ability of this system to provide a mass flow measurement

was established in almost 4000 hours of operational experience. The report

itself was a provisional accuracy statement and during the six years of

operations more precise measures of systematic error have been made which

should allow the uncertainty statement to be improved significantly.

However, if the accuracy of this system could be maintained while adding a regenerative heat exchanger and gas flowmeter test section, the improvement

in measurements of a gas mass flow reference would be significant. Present

estimates of the latter are between plus or minus one and two percent, therefore, an improvement could be realized of between five and ten over present

methods.

The process fluid used in the facility of figure 5 is nitrogen although

argon has also been used successfully. The system itself could be adapted

to other cryogenic fluids such as air, oxygen, hydrogen, methane, ethane,

propane and liquefied natural gas.

4. Applications

The potential for such a system, if the total uncertainty can be maintained at +0.2% or less, is impressive and would allow the following studies:

o Redefinition of gas flowmeter factors relative to mass flow

directly and continuously. No intermediate calculations or approximations are required.

o Gas flow pressures and temperatures could be controlled independently of the mass flow reference and would allow wide variations

in experimental conditions. An added benefit, particularly in

the case of nitrogen as the process fluid, would be that the

Reynolds number can be increased by a factor of 4 or 5 by reducing

the temperature and therefore the viscosity of the gas.

o Gas flowmeter performance could be compared directly with existing

codes and standards which are based on volumetric or water calibration predictive calculations. Errors in predictive correlations

could be identified and corrected.

o The working hypothesis that water calibration may be transferred

directly to gas flow can be tested to an accuracy not previously

possible. Errors in this hypothesis can be identified and corrected.

o The effects of upstream and downstream meter flow conditioning

(straight runs and/or flow straighteners) can be redefined with

gas flow with greater accuracy than previously available.

o Evaluations of potential gas flow transfer standards on a long

term mass flow basis. This would include such devices as the

choked nozzle and other new devices such as the laser Doppler

velocimeter or ultrasonic meters, the success of which would make

gas flow or water flow reference systems increasingly unnecessary.

38
0 An evaluation of velocity effects on direct reading densitometers.

This work would be in support of the development of a natural gas

energy meter.

o As a precision reference system, test sections could be used to

investigate the development of boundary layer and turbulence, and

the effects of these phenomena on gas meter size.

Component design would be heavily influenced by the selection of the

fluids to be used. If multiple fluids were to be tested, then components

must be designed for the most severe conditions. This would particularly

be the case in the selection of pressure pump and regenerative heat ex- changer. Table 1 is the result of calculations made on two different

applications. The methane/LNG system was based on a flow rate of 16.4

cubic meters per second (50 MMCFD). It is believed that a system of this

size would meet many of the natural gas industry requirements for flow

calibration in meter studies.

The nitrogen example is basically a modification of the existing

cryogenic flow facility to demonstrate the feasibility of the gas flow

measurement reference system. The gas flow rate of 1.2 cubic meters per

second (2750 SCFM) would be of such a capacity as to allow testing of

existing codes and practices and at the same time would not require a large

investment in heat exchange or pressure pump equipment.

Other applications are also possible and a reduction in size of the

facility for small flow should also be feasible. This suggests that a small portable gas measurement mass flow standard could be constructed and

used routinely for field calibration and certification of meters.

5. Summary

Direct comparison of ambient temperature gas flow measurements to mass

is made possible by a new continuous closed loop measurement method. The

direct comparison is made possible by modification of a proven flow refer- ence system based on mass-time. The anticipated total uncertainty in mass

flow of gas at operating conditions should not exceed +0.2%. This is an improvement of a factor of 5 to 10 over existing gas flow standards.

At a time when natural resources and raw materials are decreasing in

quantity and increasing in cost, it is believed that new measurement

methods, such as proposed, are essential to provide the necessary measure of

accuracy and precision for establishing product quantity and value.

39
Table 1. Examples of application of gas mass system.

Methane/LNG Nitrogen

Gas Side

* Flow rate (nr/s) 16.4 1.2

Pressure (MPa) 5.5 3.4

Temperature (K) 289-300 289-300

Pipe diameter (cm) 20-25 10-15

Heat Exchanger

Heat transfer load (MJ/s) 9.27 0.52

Liquid Side

Weigh tank capacity (nr) 3.8 0.379

Catch tank capacity (nr) 5.7 0.433

Pressure (MPa) 0.83 0.69

Temperature (K) 100.0 80.0

Pipe diameter (cm) 10.0 7.6

Pressure Pump

1 Flow rate (m /s) 0.027 0.001'

Pressure ratio 6.6 5.1

Power Requirement (kJ/s) 395.0 16.04

* @0*1 MPa and 289 K(14.73 psia and 60 F)

40
REFERENCES

ISA; Ad Hoc Committee Report of Flow Measurements, Instrument Society of

America, Pittsburgh, PA (1967).

Mann, D. B. , Cryogenic flowmetering research at NBS, Cryogenics 1J_, 179

(1971).

J. W. Dean, J. A. Brennan and D. B. Mann, Cryogenic flow research facility

of the National Bureau of Standards, Advances in Cryogenic Engineering T4,

(Plenum Press, New York, 1969).

D. B. Mann, J. W. Dean, J. A. Brennan, and C. H. Kneebone, Cryogenic Flow

Research Facility, (Unpublished NBS report to sponsor, Jan. 1970).

J. W. Dean, J. A. Brennan, D. B. Mann and C. H. Kneebone, Cryogenic flow

research facility provisional accuracy statement, Nat. Bur. Stand. (U.S.)

Tech. Note 606 (1971).

J. A. Brennan, J. W. Dean, D. B. Mann and C. H. Kneebone, An evaluation of

cryogenic positive displacement volumetric flowmeters, Nat. Bur. Stand.

(U.S.) Tech. Note 605 (1971).

J. A. Brennan, R. W. Stokes, D. B. Mann and C. H. Kneebone, An evaluation

of several cryogenic turbine flowmeters, Nat. Bur. Stand. (U.S.) Tech.

Note 624 (1972).

J. A. Brennan, R. W. Stokes, C. H. Kneebone and D. B. Mann, An evaluation of

selected angular momentum, vortex shedding and orifice cryogenic flowmeters,

Nat. Bur. Stand. (U.S.) Tech. Note 650 (1974).

National Bureau of Standards, Specifications, tolerances, and other technical

requirements for commercial weighing and measuring devices, Nat. Bur. Stand.

(U.S.) Handbook 44, 4th Ed. w/revisions (1972).

41
1 . Title. SURVEY OF CURRENT LITERATURE ON LNG AND METHANE

Principal Investigator . Neil A. Olien

2. Cost Center Number . 7369574

3. Sponsor Project Identification. Gas Research Institute Grant No.

5014-361-0131.

4. Introduction . It is important that all NBS personnel working in LNG, as well as the AGA , GRI , and others, keep up with what is going on throughout the world in the LNG field. This project is designed to

provide the Current Awareness and other information services to allow

workers to keep abreast of new research and other developments.

5. Objectives or Goals . We will publish and distribute each April, July,

October, and January a listing of all significant papers, reports, and

patents relating to methane and LNG properties and technology. The

references will be listed under convenient subject headings. The

Quarterly will be distributed to all interested AGA member companies and

be made available to the general public on a subscription basis. In

addition, LNG-related information will be entered into the Cryogenic

Data Center's Information System for quick retrieval. A systematic

review of the current publication scene is maintained for any new periodicals to be reviewed cover-to-cover . Finally we will update and

make available comprehensive bibliographies on the properties and

technology of LNG. There are four bibliographies involved: methane

properties, methane mixtures properties, processes and equipment

involving methane and LNG, and patents relating to methane and LNG

technology. These four will be updated annually.

6. Background . In 1969 we made a thorough review of the world's publications to determine which periodicals and abstracting services should be

scanned cover-to-cover to adequately encompass the LNG field. The

result is that we now scan over 330 primary publications and nearly 25

secondary publications. Of these, approximately one-third are directly

related to LNG. In addition, we have increased our coverage of the

energy field to include SNG (coal gas, hydrogen, etc.). Much of this

information is also pertinent to LNG and as such is listed in our LNG-related publications. Our Current Awareness Service has been

published weekly since 1964 (beginning in 1975 the publication became

biweekly) and the Liquefied Natural Gas Survey has been published

quarterly since 1970.

7. Program and Results . Four issues of the LNG Quarterly are prepared each

year and distributed. There are now 131 subscriptions going to AGA

Member Companies and 153 to other subscribers.

The size of the four comprehensive bibliographies mentioned in section 5 above has grown to the extent that their usefulness is limited,

therefore it was decided that they would not be updated and a series of more specialized bibliographies would be made available. The following

list gives those currently available. Additional topics will be added

as necessary. The listed bibliographies were updated in August 1979.

B-1820 LIQUEFIED NATURAL GAS STORAGE INCLUDING INSULATION SYSTEMS.

225 pages, 1264 references, author and subject indexes $20.00

B-1821 LIQUEFIED NATURAL GAS PEAKSHAVING AND SATELLITE OPERATIONS.

39 pages, 230 references, author index $10.00

B-1822 LIQUEFIED NATURAL GAS STRATIFICATION AND ROLLOVER.

10 pages, 40 references, author and subject indexes $ 5.00

42
B-1823 LIQUEFIED

82 pages.

NATURAL GAS SAFETY INCLUDING SPILLS.

421 references, author and subject indexes $10.00

B-1824 LIQUEFIED

48 pages.

NATURAL GAS PIPELINES AND TRANSFER LINES.

249 references, author index $10.00

B-1825 LIQUEFIED

154 pages

NATURAL GAS SHIPS, BARGES AND OVERWATER TRANSPORTATION.

, 892 references, author index $15.00

B-1826 LIQUEFIED

64 pages,

NATURAL GAS VAPORIZORS INCLUDING COLD UTILIZATION.

356 references, author and subject indexes $10.00

B-1827 LIQUEFIED

38 pages.

NATURAL GAS HEAT TRANSFER.

170 references, author index $10.00

B-1828 LIQUEFIED

102 pages

NATURAL GAS LIQUEFACTION AND REFRIGERATION.

, 585 references, author and subject indexes $15.00

B-1829 LIQUEFIED

92 pages.

NATURAL GAS ECONOMIC FACTORS.

513 references, author index $15.00

B-1830 LIQUEFIED

15 pages.

NATURAL GAS OVERLAND TRANSPORTATION.

81 references, author index $ 5.00

B-1831 LIQUEFIED

250 pages

NATURAL GAS PATENTS.

, 1595 references, author and subject indexes $20.00

B-1832 LIQUEFIED

30 pages.

NATURAL GAS INSTRUMENTATION.

110 references, author and subject indexes $ 5.00

8. Problem Areas . None.

9. Level of Effort . July 1 - December 31, 1979

Staff-years expended

Equipment and/or Services Purchased

Approximate expenditures, total

0.25

3 . 5K$

9 . 4K$

10. Future Plans . Issue 79-4 was delivered to the printer the third week of

January and should be distributed in early February.

43
/

: 79-WA/HT-19 ' ' AN ASME PUBLICATION -7 $3 00 per copy $1.50 to ASME Members /

^TENfy/,q THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS

345 E 47 St., New York, N.Y. 10017

Tne Society shall not be responsible tor statements or opinions advanced in papers or

in discussion at meetings ot the Society or of its Divisions or Sections, or printed in

its publications Di-scussion is printed only if the paper is published in an ASME

Journal or Proceedings Released tor general publication upon presentation. Full credit should be given to ASME. the Technical Division, and the author(s).

HA. Olsen

Thermophysical Properties Division, National Engineering Laboratory,

National Bureau of Standards,

Boulder, Colo.

Present and Future Sources of

Fluid Property Data

Fluid Property calculations for the design and operation of large process systems

require that the data used by the engineer be in a computer compatible form. This,

in turn, places complex demands on those of us in the data generation and

correlation field. The responsibility of the producers of data, i.e., experimentalists,

theorists or correlators, to the ultimate users of the data such as design engineers is discussed, because the efficient transfer of data from the originator to the ultimate user is absolutely essential. The specific requirements for data in the future will be for ‘black box’ type computer-compatible routines to calculate broad ranges of

thermophysical properties for pure fluids and mixtures. Although calculational packages are very useful tools, reliance on them by the uninformed can lead to costly design errors and there is some evidence that the existence of the packages

may tend to reduce future research in fluid properties. Generic solutions to the future data requirements of the chemical process and energy industries will place

heavy reliance on theoretical approaches. Illustrations of the future data requirements ofspecific industries are given as examples.

ABSTRACT

Fluid Property calculations for the design and

operation of large process systems require that the data used by the engineer be in a computer compatible

form. This in turn places complex demands on those

of us in the data generation and correlation field.

The responsibility of the producers of data, i.e.,

experimentalists, theorists or correlators, to the ultimate users of the data such as design engineers

is discussed, because the efficient transfer of data

from the originator to the ultimate user is absolutely essential.

The specific requirements for data in the future

will be for 'black box' type computer-compatible

routines to calculate broad ranges of thermophysical

properties for pure fluids and mixtures. Although

calculational packages are very useful tools, reli- ance on them by the uninformed can lead to costly

design errors and there Is some evidence that the existence of the packages may tend to reduce future

research in fluid properties. Generic solutions to the future data requirements of the chemical process

and energy industries will place heavy reliance on theoretical approaches. Illustrations of the future

data requirements of specific industries are given as examples

.

INTRODUCTION

We have witnessed an increasing emphasis on more sophisticated forms of fluid property data over the past several decades. One large factor in this

emphasis was the emergence of the aerospace Industry

Contributed by the Heat Transfer Division of The American Society of Mechanical Engineers for presentation at the Winter Annual Meeting, New

York, N.Y., December 2-7, 1979. Manuscript received at ASME Headquarters August 10, 1979. Copies will be available until September 1 , 1980.

and the many requirements imposed by NASA, some of which were described In the previous paper (1). The

modern computer, of course, was another major factor,

but NASA and its stringent demands for very high accuracy and reliability truly set us on a path from

looking up discrete values In handbooks to representing a continuum of properties with computer

programs. One of the pioneering efforts in this was

the refinement of the Benedict-Webb-Rubln equation of state by Strobridge (2), an effort which was only

possible because of the modern digital computer.

Calculations, as such, however, are not new. James

Conant, the former president of Harvard tells a story, perhaps apocryphal, that took place during

World War I (3). When President Wilson appointed a board, with Thomas Edison as chairman, to give

scientific advice to the Navy during the course of the war, one of the members chosen by Edison was a physicist from the National Bureau of Standards.

Edison told the President that the reason for the presence of the physicist was, "we might have one mathematical fellow In case we have to calculate

something out." I am not sure whether the story Is appropriate or not In this centenary of Edison's

greatest invention (4). Some things have changed

since 1918. The direction we are taking In mathematical modeling and the concurrent rapid

increase in speed and storage capacity of computers

means that the changes will come at an even faster

rate. The advent of the microprocessor and other

offspring of large scale Integration serve to magnify

this trend. Those of us producing data must be prepared to be active participants in the introduction of our data and the form of our data

into industrial automation. We must work with

current and emerging industries to see that they have

the best data and formulations available for their

use. It is not enough to make excellent

measurements, develop magnificent equations of state

and the like. I can say from experience that the

44
probability of use of data, models, etc. in industry

approaches zero as the estoric nature of the data and

nodels increases. To put it bluntly, if data are difficult to find or hard to use they just will not

be utilized. The automation trend mentioned

previously serves only to strengthen this tendency.

I say this despite the large economic incentives of using more accurate data.

ECONOMIC IMPACT AND LEVERAGE

There have been several studies and estimates

made of the economic impact on selected industries of inaccuracies in fluid property data (5, 6, 7, 8, 9). One

such study is included in this meeting of the

kSME. (10). David Zudketvitch has done a great deal

in this field and has recently shown (11) that the capital and operating costs of several types of plants can be significantly reduced as a result of increased accuracy (reliability and reduced error

bands) of thermophysical property data. Table 1 shows the relative importance of several kinds of

data on the design of various parts of process

plants.' The information in this table is taken from

the pioneering work of Zudkevitch (12). It is readily apparent that phase equilibria data are the most vital. This is because the equipment (heat

exchangers, distillation columns, compressors, etc.)

associated with fluid separation processes is the

most capital and energy intensive part of process

plants. The large number of liquid-vapor equilibrium

correlation techniques gives further credence to the industrial importance of this class of thermodynamic

properties. It is reasonably well established, then,

that the accuracy of the thermophysical property data

of fluids can have a significant economic impact on

the industries in which these fluids are used. Let us now look at the magnitude of this potential economic

impact.

The chemical process and fuels industries have current annual capital requirements in excess of $50

billion, with the bulk of this in conventional

processes and feedstocks. The period 1979-2000

however is a period of transition for these

industries with a change to unconventional base

feedstocks (principally coal). As an example the American Gas Association has estimated the capital

requirements for coal gasif ication/synthetic gas

(SNG) for the period 1978-2000 to be $62.9 billion

(see table 2). Liquefied natural gas (LNG)

requirements will also be substantial with $7.9

billion for import terminal construction alone in the period 1978-1990. If we add to this the capital

requirements for associated distribution and storage

systems and dedicated auxiliary plants (e.g., air

separation plants for coal gasification and LNG peak

shaving facilities) we have projected total requirements in the period 1978-1990 of $83.6 billion and in the period 1991-2000 of $91.5 billion. This $175.1

billion in capital investment will be for process plants and associated equipment involving fluid

mixtures ranging from six to eight component LNG to 20 plus component mixtures in coal gas plants. If we remember that this is for supplemental gas for the gaseous fuel industry we can get some idea of the

magnitude of the projected capital costs for the total of industries involving mixtures. The

potential savings in new plant construction and

modification of existing plant as a result of the

availability of more accurate data and models is of

Table 1.

BEL ATI VE IMPORTANCE 6F SOME THERMODYNAMIC VARIABLES

8N DESIGN AND PERFORMANCE - EVALUATION OF BASIC

PROCESS

VAPII PRESSURE AMI: AH

Atari C

p

AS

RATE DATA

DENSITY P-V-T

CRITICALS PRASE

DISTRIBUTION

ELECTROLYTE

IONIZATION

TRANSPORT REACTION

iEACTOSS c 1 B s 8 B B A

FR ACTIIR ATIRS 1 1 A k B 0 E S

EXTRACT8RS I 0 h 0 or S C 0 8 s

NEAT EXCHANGERS c 1 h S A c B s

COMPRESSORS

1 EXPANDERS A A k A B 0 s

METERING

(AND SALES] k

... e

... S

...

MATERIALS OF CONSTRUCTION 8

... B A

... ... s

POLLUTION ABATEMENT

...

... A k C

... A A

RET: A - last important D -

B - Very important

C - Influences calculations, N -

1st accuracy not critical S -

Considered only in preliminary

selection

Not applicable

Important in specific cases

45
Table 2. Capital Requirements - Supplemental Gas for U .S

.

(Billions of 1977 Dollars)

Coal Gasif ication/SNG

1978-1990

20.4

1991-2000

42.5

Total

62.9 LNG Importation 7.9 2.0 9.9

Transmission, etc. 55.3 47.0 102.3

Total 83.6 91.5 175.1

Source: Anderson, R., AGA Monthly 60, 30-3 (Apr 1978).

the order of tens of millions of dollars per year. The studies mentioned above also tell us that the savings in operating costs over the life of the plant can be even greater than the savings in capital

costs

.

EXISTING TABLES OF FLUID PROPERTY DATA

Although there is a strong trend today toward

the use of computerized models for calculating fluid

property data, tables of property data are still

widely used. Table 3 lists some of the more useful

of the existing collections which include data on many fluids. You will note that there is a lack of uniformity in the sources of these publications.

Table 3. Collections of Fluid Property Data

LNG MATERIALS AND FLUIDS - A USER'S MANUAL OF PROPERTY DATA IN GRAPHIC FORMAT, D. B. Mann,

Editor, National Bureau of Standards,

Thermophysical Properties Division, Boulder, CO 80303 (1977) (Supplement 1 - 1978; Supplement

2 - 1979)

THERMOPHYSICAL PROPERTIES OF MATTER/THE TPRC DATA SERIES, Y. S. Touloukian and C. Y. Ho,

Editors, Plenum Press, N.Y.

SELECTED VALUES OF PROPERTIES OF HYDROCARBONS

AND RELATED COMPOUNDS, Thermodynamics Research

Center, Texas A&M Univ. , College Station, TX 77843 (also a companion volume on other chemical

compounds)

GAS ENCYCLOPAEDIA, L'Air Liquide, Division

Sclentifique, Elsevier/NorthHolland , Inc

.

(1976)

ENGINEERING DATA BOOK, Gas Processors Assn.,

Tulsa, OK (1972)

ASHRAE THERMODYNAMIC PROPERTIES OF REFRIGERANTS,

Amer. Soc. of Heating, Refrigerating and Air

Conditioning Engrs. , 345 East 47th St. , N.Y. 10017 (1969)

THERMODYNAMIC PROPERTIES AND REDUCED

CORRELATIONS FOR GASES, L. N. Canjar and F. S. Manning, Gulf Publishing Co. (1967)

PHYSICAL PROPERTIES - A GUIDE TO THE PHYSICAL,

THERMODYNAMIC AND TRANSPORT PROPERTIES OF INDUSTRIALLY IMPORTANT CHEMICAL COMPOUNDS, C. L. Yaws, McGraw-Hill (1977)

MATHESON GAS DATA BOOK, W. Braker and A. L. Mossman, Matheson Gas Products, East Ratherford,

N.J. (1971)

They have been prepared by societies, government

agencies, private firms and universities . There are also a number of sets of standard reference data or at least quasi-standard data for equilibrium

properties for individual fluids (see table 4) . You will notice that some of these are in the process of being revised or at least new versions are definitely

planned. The argon and carbon monoxide publications are in great need of revision, but to my knowledge,

no definite correlations or critical evaluations are underway. In the case of argon, we have a fluid of relatively small industrial importance, but argon is used so much as a standard for predictions as well as for testing new apparatus that its importance cannot

be overemphasized. The state-of-the-art in equations

of state has Increased significantly since the publication of the Argon Standard Reference Data (13) by the NBS-Office of Standard Reference Data. In addition, a large number of new measurements have been made . The other fluid needing a new correlation

is carbon monoxide. I recently completed an informal survey on CO and found to my surprise, that the best wide range tables (14,15) are nearly a quarter of a century old. Another set of tables (16), of slightly newer vintage, does exist, but is limited to the temperature region below 300 K.

METHODS OF CALCULATING FLUID PROPERTY DATA

Many of the references given in table 4 include calculational methods (equations of state) . Table 5 lists some calculational methods, the broadest of which is the recently revised Reid, Prausnltz and Sherwood (17). A number of computer calculation

packages are available on time-sharing networks for a user fee or for outright purchase. There is even a computer package available in the Soviet Union called AVESTA as illustrated in figure 1. AVESTA stands for Automatic Variable Engineering System of Thermophysical Advance. There are dangers in using

computerized calculation packages, since the user can derive a false sense of security about the accuracy

of the data returned. The danger is amplified when

the data are used directly in computer calculations

for plant design and operation. In the latter case the engineer never sees the data and he or she does not have a chance to apply good engineering judgement

to the fluid property data. Often higher level

managers in technical firms develop a feeling that the calculation packages provide data which have very small or non-existent error bars. This is both disquieting and dangerous. I have heard of a vice-president in the LNG industry who stated that they did not need any more work on LNG phase

equilibria, because his company subscribed to a computer package which provided all of that. To illustrate the folly of such a pronouncement, let us examine figure 2. Elliott, et al. (18) made a comparison of K-value calculations from ten different
Table 4. Standard Data for Individual Fluids

Fluid Source

McCarty, R. D. , NASA SP-3089

(1975)

McCarty, R. D., J. Phys. Chem.

Ref. Data 2 , 923 (1973)

Angus, S., et al., Intern. Thermodynamic Tables of the Fluid

State - 4, Butterworths (1977)

N 2 * Jacobsen, R. T. and Stewart,

R. B., J. Phys. Chem. Ref. Data

2 , 757 (1973)

02 Roder, H. M. and Weber, L. A., NASA SP-3071 (1972)

F 2 Prydz, R. and Straty, G. C., NBS Tech. Note 392 Rev. (1973)

He

and

Ar Gosman, A. L., McCarty, R. D.,

et al., NSRDS-NBS 27 (1969)

and Angus, S., et al., Intern. Thermodynamic Tables of the Fluid

State - 1, Pergamon (1971)

CO Din, F., Thermodynamic Functions

of Gases, Vol. I, Butterworths

(1956)

CO2 Angus, S., et al., Intern. Thermodynamic Tables of the Fluid

State - 3, Pergamon (1976)

^3 Haar, L. and Gallagher, J. S.,

J. Phys. Chem. Ref. Data 7

_, 635 (1978) ~

CH4 Goodwin, R. D., NBS Tech. Note

653 (1974)

and Angus, S. , et al . , Intern. Thermodynamic Tables of the Fluid

State - 5, Pergamon (1978)

c

2 h6 Goodwin, R. D., et al., NBS

Tech. Note 684 (1976)

c 3 h8 * Goodwin, R. D., NBSIR 77-860

(1977)

* n_c4H 10 Goodwin, R. D. , NBSIR 79-

(1979)

1_c4 h10 Goodwin, R. D. , NBSIR 79-

(1979)

^2^4 * Angus, S., et al . , Intern. Thermodynamic Tables of the fluid State - 2, Butterworths (1974)

^3^6 * Juza, J. , et al., Acta Tech.

(Prague) 23, 425 (1978)

Table 5. Calculation and Estimation Techniques

THE PROPERTIES OF GASES AND LIQUIDS, Third

Edition, Reid, R. C., Prausnitz, J. M. and

Sherwood, T. K., McGraw-Hill (1977)

PHYSICAL PROPERTIES - A GUIDE TO THE PHYSICAL,

THERMODYNAMIC AND TRANSPORT PROPERTIES OF INDUSTRIALLY IMPORTANT CHEMICAL COMPOUNDS, C. L. Yaws, McGraw-Hill (1977)

A NEW TWO-CONSTANT EQUATION OF STATE, D. Y. Peng

and D. B. Robinson, Ind. Eng. Chem. Fundam. 15 , 59 (1976)(For a review of this and other phase

equilibria models, see Renon, H., Fluid Phase

Equilibria 2 , 101 (1978)

A COMPARISON OF MATHEMATICAL MODELS FOR THE PREDICTION OF LNG DENSITIES, R. D. McCarty, Nat. Bur. Stand. Interagency Report, NBSIR 77-867

(1977)

COMPUTER CALCULATION SYSTEMS, some examples are: CHEMTRAN/CHEMSHARE, CHESS, GPA CONV, SSI,

FLOWTRAN, PDA, PPDS, TAP, etc.

TE/lEnPECCPEK/lAMA

TEI.EI’RESSREKLAMA

KMEB - 1978 K I E,V — 1978

Figure 1. AVESTA-Automated Property Calculation

Package from the USSR.

computer packages. K-values are very useful in designing separation plants and are defined as

Automatic

IferfebNr L- engineering ' .system of

‘Ihermonhysicerf

advance

*Newer versions underway or planned.

47
Figure 2. Comparison of K-Value Calculation Methods for Natural Gas.

K = y 1/x

i where: = molar concentration of

th the i component in the

vapor phase and x^ = molar

th concentration of the i component in the liquid

phase.

In figure 2 I have shown the deviation of five of these methods from a sixth, arbitrarily chosen. The

horizontal axis gives the molecular species

(Ci=methane, C2=ethane, etc.), and the last item

is the total volume of all liquids condensed. I think it would be very difficult to maintain that any

of those methods represents scientific truth. In fact, the methods examined by Elliott and presented

here represent three different approaches to K-value

predicting - i.e., conformal solution theory, van der

Waals' techniques and empirical methods. One further

disadvantage of the widespread availability of these

packages was hinted at above. In a conversation with

Professor Kobayashi of Rice University a few months

ago, he and I agreed that the computer packages tend

to stifle research. The attitude expressed by the vice-president mentioned above certainly does not encourage grants and contracts for needed research

work. If it sounds as if I am advocating the elimination of calculation techniques, especially

11 computerized methods, let me assure you that this is not the case.

DISSEMINATION OF FLUID PROPERTY DATA IN THE FUTURE

I firmly believe that computerized calculation

methods for fluid properties, especially mixture

properties, will become commonplace in the future.

First, automation in design requires automation in data; second, data needs are so great as to demand

the use of semi-automated calculations; and third, in / the case of mixtures, tables are just not practical. How can we do this and still avoid the disadvantages

described above? It is essential that calculational

packages be accompanied by well documented and justified confidence limits, the existence and use of which is clearly understood by the users of the packages. In addition, the package should contain

provisions for notifying the user when calculations

are requested which are outside the range of the particular method used. What is needed is a 'truth

in packaging' requirement for calculational techniques. A little earlier, I said that producers of data (experimenters, theorists or correlators) must

be prepared to participate in the introduction of their data and models into industry. They must also

do their part to prevent their data from being

misused, i.e., unwarranted extrapolations. The J

objective should be wide-range and accurate models,

which can be easily used and which, if they do not prevent Improper use, at least clearly provide ^

warnings of perils ahead. One of the blessings of

48
the modern computer is the ease with which we can provide for warnings of this sort. Often the engineer is either faced with a need

for professional advice about calculational methods

and data or is at a loss as to where to turn. In these cases, it is important to make a personal

contact with knowledgable experts in fluid

properties. Table 6 lists several 'Data' or 'Information Analysis Centers' which can be of great

assistance to the engineer.

Table 6. Fluid Property Data Centers

Chemical Kinetics Information Center

NBS - Robert F. Hampson, (301) 921-1000,

extension 2565

Chemical Propulsion Information Agency

Johns Hopkins, (301) 953-7100

Chemical Thermodynamics Data Center

NBS - Donald D. Wayman, (301) 921-1000,

extension 2773

Cryogenic Data Center

NBS - Neil A. Olien, (303) 499-1000, extension

3257

Electrolyte Data Center

NBS - Bert R. Staples, (301) 921-1000, extension

3632

Thermodynamics Research Center

Texas A&M - R. C. Wilhoit, (713) 846-8765

Thermophysical Properties Research Center

Purdue - W. H. Shafer, (800) 428-7675

EXPANDED NBS PROGRAM IN FLUID PROPERTY RESEARCH

The Thermophysical Properties Division at NBS-Boulder has embarked on a long range effort to develop generic techniques for predicting the thermophysical properties of a broad range of industrial

fluids. We are building on the experience we have

gained through our participation in programs in

liquefied natural gas (LNG) (primarily funded by the American Gas Association and the Gas Research

Institute) and ethylene properties (a joint

government-industry program, managed by the NBSOffice of Standard Reference Data). Our work has

established a rational approach to the development of accurate and useful mathematical models. This

approach involves the judicious marriage of

experimental measurements, theoretical studies,

mathematical modeling and a continuing interaction

with current and future users of the models and data.

The measurement aspect of this integrated program

will occupy a substantial fraction of the available

resources, but even at that we realize that the plan

will be measurement limited. The measurements will

be primarily on pure components and binary systems,

with a strong need for very careful choice in fluids

and measurement ranges. In addition the measurements

must be of high quality, as the literature is replete

with examples of measurements of little or no use

because of the high uncertainty of the results. A

purely experimental approach to mixtures properties

rapidly leads to an infinite data requirement;

therefore, theoretically based models must play a

large role in the entire project. It is difficult to separate the theoretical efforts from the mathematical modeling work. We are conducting and have plans

to accelerate our experiments wherein fluids are modeled in a computer by the techniques of molecular

dynamics (19). These methods have the potential of

becoming very powerful tools in the quest for a basic

understanding of fluid behavior and the development

of soundly based methods of predicting the properties

of complex fluid mixtures. One area which requires a large amount of attention is the need for quantitative understanding of the interactions between unlike

molecules. Included in this are molecules of disparate sizes (e.g., molecular mass ratios of 25 or greater) and even more complex interactions (e.g.,

polar-nonpolar interactions.)

All of this cannot be accomplished by one group

in Boulder and we thus plan to continue a large

number of very productive technical collaborations. Two of these are with the Thermophysics Division and

the Office of Standard Reference Data, both located

in the National Measurement Laboratory of NBS-Gaithersburg

.

CONCLUSION

Even the person on the street is aware of the pervasiveness of the computer in all aspects of modern life, industrial and otherwise. This trend,

will continue and people producing fluid property

data and models must consider this trend in

consideration of the future. These computerized

mathematical models must be developed with a combination of intelligence and pragmatism. We must have a clear picture of our engineering customers and their requirements. They in turn must understand

what they are getting from us and how best to use the tools we provide.

REFERENCES

1 Hendricks, R. C., "Thermophysical Property Data - Who Needs Them," Amer. Soc. Mech. Eng.,

Winter Annual Meeting, Dec. 2-7, 1979, Paper WA-HT-.

2 Strobridge, T. R., "The Thermodynamic

Properties of Nitrogen from 64 to 300 K Between 0.1 and 200 Atmospheres," Nat. Bur. Stand. (U.S.), Tech. Note 129, 85 pp (1962).

3 Conant, J. B., "Modern Science and Modern

Man," Columbia Univ. Press (1952).

4 EPRI Journal, Vol 4, No. 2 (Mar 1979). A Special Issue Commemorating the lOO 1-*1 Anniversary

of Edison's Invention of a Practical Electric

Lighting System.

5 Medina, A. G., McDermott, C. and Ashton, N., "On the Effect of Experimental Error on the Calculation of the Number of Stages for a Given

Distillation Separation," Chem. Eng. Sci. 29_, 2279

(1974).

6 Zudkevitch, D., "Imprecise Data Impacts

Plant Design and Operation," Hydrocarbon Proc. _54^ 97 (Mar 1975).

7 Williams, C. C. and Albright, M. A., "Better Data Saves Energy," Hydrocarbon Proc. 115 (May

1976).

8 Mah, R. S. H., "Effects of Thermophysical

Property Estimation on Process Design," Chem. Eng.

Comput. 183 (1977).

49
9 Yen, L. C., Frith, J. F. S., Chao, K. C. and Lin, H. M. , "Data Deficiency Hampers CoalGasi fixation

Plant Design," Chem. Eng. ^4, 127 (May 9, 1977).

10 Khalifa, H. E. and Kestin, J., "The

Influence of Thermophysical Properties on the Design

and Sizing of Geothermal Power Plant Components,"

Amer. Soc. Mech. Eng., Winter Annual Meeting,

Dec. 2-7, 1979, Paper WA-HT-.

11 Zudkevitch, D., "Impact of Thermodynamic and

Fluid Properties Data Uncertainties on Design and

Economics of Separation Operations," The Encyclopedia

of Chemical Processing and Design (to be published).

12 Zudkevitch, D. and Gray, R. D. , Jr., "Impact

of Fluid Properties on the Design of Equipment for Handling LNG," Adv. Cryogenic Eng. Vol 20, 103 (1975).

13 Gosman, A. L., McCarty, R. D. and Hust, J.

G. , "Thermodynamic Properties of Argon from the Triple Point to 300 K at Pressures to 1000

Atmospheres," Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. No. 27, 152 pp (1969).

14 Hilsenrath, J., Beckett, C. W., et al.,

"Tables of Thermal Properties of Gases," Nat. Bur. Stand. Circ. No. 564 (1955).

15 Din, F. , Editor, "Thermodynamic Functions of Gases, Vol I. Ammonia, Carbon Dioxide and Carbon

Monoxide," Butterworths Scientific Publications

(1956).

16 Hust, J. G. and Stewart, R. B. , "Thermodynamic Property Values for Gaseous and Liquid Carbon

Monoxide from 70 to 300 K with Pressures to 300

Atmospheres," Nat. Bur. Stand. (U.S.), Tech. Note 202

(1963)

.

17 Reid, R. C . , Prausnitz, J. M. and Sherwood,

T. K. , "The Properties of Gases and Liquids," Third

Edition, McGraw-Hill (1977).

18 Elliot, D. G., Chappelear, P. S., et al.

,

"Thermophysical Properties: Their Effects on Cryogenic Gas Processing," Phase Equilibria and Fluid

Properties in the Chemical Industry, ACS Symposium

Series, 60, p. 289-315, T. S. Storvick and S. I. Sandler, Editors, American Chemical Soc. (1977).

19 Hanley, H. J. M. and Watts, R. 0.,

"Molecular Dynamics Calculation of the Thermodynamic

Properties of Methane," Aust. J. Phys . 28 , 315 (1975).

50
1 . Title, liquefied natural gas technology transfer

Principal Investigators . D. E. Diller, H. M. Ledbetter, L. L. Sparks,

and N. A. Olien

2. Cost Center Numbers . 7360403, 7364574, 7368574, 7360594, 5621510

3. Sponsor Project Identification . Maritime Administration, Miscellaneous

Purchase Order No. 400-79005; American Gas Association, Inc. Project

BR-50-10; Gas Research Institute; NBS Office of Standard Reference

Data

.

4. Introduction . The liquefied natural gas program at the Thermophysical

Properties Division of NBS Boulder represents an investment by industry

and government agencies of over $7 million over the past six years.

This investment was designed to develop reference quality properties

data for both fluids and materials and instrumentation and measurement

technology for the use of the LNG and related industries. Information

developed under this program must be transmitted to the ultimate user in

a timely and useful format. The classical publication methods of NBS

most certainly provide the scientist and research engineer information

in a form most useful to the academic or near academic community.

However, as a result of extensive assessments of user requirements, it was found that an additional effective mode for technology transfer

would be an LNG Materials and Fluids User’s Manual. A complete outline

and planned table of contents have appeared in previous semiannual

reports. The Maritime Administration of the Department of Commerce and

the American Bureau of Shipping agreeded to sponsor the first year's

efforts on the materials section, and the American Gas Association, Inc.

and the NBS Office of Standard Reference Data agreeded to sponsor the

section on fluids and fluid mixtures. The project was begun on April 1,

1976.

5. Objectives or Goals . The Liquefied Natural Gas Materials and Fluids

User's Manual will provide a method of quick dissemination of property

data and related information for the effective generation, utilization

and transportation of LNG. The object is to improve technology transfer

from the current NBS Thermophysical Properties Division LNG physical

measurements program to the users, including federal agencies, the

states and industry. For the purpose of this data book, liquefied

natural gas is defined as a cryogenic mixture (at less than

approximately 150 K) of hydrocarbons, predominantly methane, with less

than a total of 20% of the minor components ethane, propane, iso and

normal butane, and nitrogen as an inert contaminant. LNG materials will

be those associated with the liquefaction, transport and storage of

liquefied natural gas.

6. Background . The User's Manual is only one of a number of information

dissemination methods used to provide workers in the liquefied natural

gas (LNG) industry with properties data of known quality in a format

consistent with the requirements of the intended user. In the case of

the LNG User's Manual the intended audience is the field engineer, plant

manager, ship designer or process engineer interested in a ready

reference of assessed quality for data to be used in conceptual design,

process monitoring, process analysis, and intercomparisons where

precision and accuracy are secondary to specific problem solutions. The

hierarchy of accuracy and precision will be defined and traceable

through references to scientific and engineering literature.

Data are classified into three groups by the NBS Thermophysical

Properties Division.

51
Group 1 . Data which have been generated experimentally by NBS , or have

been assessed, evaluated or experimentally verified by NBS.

Group 2 . Data which have been assessed and evaluated by NBS.

Group 3 . Data available in the scientific engineering literature

through the NBS Cryogenic Data Center or elsewhere. No NBS evaluation

or assessment has been made at this date.

In general, most data included in the LNG User's Manual is from groups 1 and 2. Few new assessments or correlations are anticipated or required

for this work.

Data are presented primarily in graphical form. Tables and analytical

expressions are used only where absolutely necessary. Graphs and charts

are in loose-leaf form for ease of updating and additions. This form

also allows immediate implementation of data already available under the

NBS LNG program and provides a convenient format for the output of data

from existing projects. The User's Manual is not be a substitute for

traditional publications in the scientific literature where measurement

science, technique, precision and accuracy are paramount, but provides

the data and references for the necessary assessment by the user.

The publication of both graphical and tabular data is in a dual system

of physical units. These units are the traditional LNG industry British

System of BTU , pound, degree Fahrenheit and the SI system of joule,

kilogram and kelvin. It is the intent to give equal weight to each

system of units.

7. Program and Results . The first edition of the User's Manual became

available for distribution in September 1977. A complete description

and ordering information are included as part of this report. Over 850

copies have now been distributed to sponsors and purchasers. New orders

are currently coming in at the rate of about ten per week. The first

supplement to the User's Manual is printed and 500 copies have been

distributed

On January 24, 1979 the LNG Materials and Fluids User's Manual received

the Award of Distinction (first place) of the Society for Technical

Communications. This award was in the category "Industrial Handbooks

and Manuals" and we believe recognized the efforts and contributions of

the sponsors and individual contributors.

Due to an initial uncertainty about the demand for the User's Manual

only 750 of the cover and dividers were ordered, however 1000 copies of

all graphs and text were printed. Our original stock of 750 was exhausted in April, therefore 250 additional covers and divider sets were ordered and are now in use for filling orders.

The second supplement has been completed. After some difficulty with

extremely high bids, a reliable printer was engaged. The second

supplement contains 28 graphs on composites, 6 on concrete, 27 updated

graphs on structural materials, 15 graphs and 3 wall charts on propane

properties and three graphs on mixture properties.

8. Problem Areas . Problems in compiling data and graph preparation delayed

delivery of some of the materials property graphs to the printer by six

weeks

.

52
9. Level of Effort . July 1 - December 31, 1979

Staff-years expended 0.6

Equipment and/or Services Purchased 14.3K$

Approximate expenditures, total 46.7K$

10. Future Plans . This work is now essentially complete. We expect the

final copy of the Second Supplement back from the printer in midJanuary. A brochure, describing the supplement, will be mailed to

current handbook owners shortly.

53
1. Title. OIML JOINT SECRETARIAT ON LNG MEASUREMENTS

Principal Investigators. Douglas B. Mann and James A. Brennan, NBS and

T. L. Hillburn, Phillips Petroleum Company.

2. Cost Center Number . 7360290

3. Sponsor Project Identification . American Gas Association, Inc.,

NBS-Office of International Standards; and NBS.

4. Introduction . The liquefied natural gas program of the National Bureau

of Standards Cryogenics Division has, over the past seven years,

provided the gas industry and interested Government agencies with

properties data on materials and fluids, instrumentation, and

measurement assistance in supplementary fossil energy supply. Support

of this program by the American Gas Association, Inc., and Federal

Government agencies such as the Maritime Administration (MarAd), NASA,

GSA , Federal Power Commission and the NBS-Office of Standard Reference

Data has provided a basis for the national acceptance of the results of

the NBS LNG program. Through the U.S. membership in the International

Organization of Legal Metrology there exists, at the present time, an opportunity to extend, internationally , the utility of data and

measurement practice developed under our joint Government/industry

program. We have been requested (by OIML membership) to establish a LNG

Measurement Secretariat within OIML which, if implemented, would provide

a significant international forum for the results of our joint work. It

is believed that a joint Secretariat with the LNG industry would provide

the most effective means of accomplishing these objectives.

5. Objectives or Goals . Our objective is to accomplish the following goals.

a) To establish U.S. (NBS) thermophysical properties data for LNG as the standard data in international usage.

b) To establish U.S. (NBS) materials property data used in fabrication

and construction of LNG facilities (liquefiers, storage, transport) as the standard data in international usage.

c) To establish U.S. (NBS) approved measurement technology and

instrumentation as related to LNG (pressure, temperature, density,

liquid level, flow) as the standard in international LNG trade. The

precedent has been established with the successful completion of the

joint NBS-CGA cryogenic flow measurement program which has resulted in

the adoption of a cryogenic flow measurement code by the National

Conference on Weights and Measures. We wish to extend this code on an international basis.

d) To establish and maintain the leadership of U.S. science,

engineering, and industry in the research, technology, manufacture and

marketing of instruments and measurement systems for liquefied natural

gas

.

6. Background . OIML was founded in 1955 to promote intergovernmental

cooperation in the field of legal metrology which relates to the

compatibility of standards of measurement and the legislation and

government regulations which may affect such standards of measurement.

OIML recommends uniform international requirements for scientific and

measurement instruments used in industry and commerce and works out

model laws and regulations for consideration by member nations; and, in

54
addition, serves as a center of documentation and information exchange

in legal metrology. At present, 43 nations are members of this

intergovernmental organization.

The United States joined OIML in 1972 (the Senate by resolution of

August 11, 1972, gave its advice and consent to the accession of the

U.S. to the convention establishing OIML). The responsibility for

managing U.S. participation in OIML was assigned to the Department of

Commerce and has since been delegated by the Department to the National

Bureau of Standards ( NBS ) . Under the general guidance of the Department

of State and the Secretary of Commerce, NBS is directly responsible for

formulating and implementing U.S. policy towards OIML. U.S. participation in the organization is deemed important for two reasons: First,

to protect and enhance some $1 billion worth of scientific and measurement instruments exported each year by U.S. firms and to ensure equity

in the trade of commodities measured by these instruments; and second,

to maintain the U.S. as the world leader in the field of metrology.

In the spring of 1975 at a meeting in Paris of the International

Committee of Legal Metrology, the French and U.S. representatives

discussed the possibility of creating a new Reporting Secretariat No. 15 on "Liquefied Natural Gas ( LNG ) Measurement." The U.S. representative,

W. E. Andrus, Jr. of NBS, agreed to explore the possibility with U.S.

industry and interested government agencies. These discussions resulted

in a decision to propose a joint Secretariat with the American Gas

Association and NBS-Cryogenics Division in order to best accomplish the

tasks. These conclusions were reached during several meetings extending

through the latter part of 1975 and early 1976. During the summer of

1977, representatives of NBS met with PTB (West Germany) and SIM

(France) to discuss the proposed scope and to explore expansion of the

effort to include cryogenic fluids in general. Results of those

discussions indicate some resistance to including different physical

measurements (flow, density, etc.) under a single recommendation for a specific group of fluids.

The proposed plan and scope were presented at the meeting of The

Advisory Committee for International Legal Metrology held at NBS-Boulder

in September. The committee encouraged NBS to proceed with the present

scope and to continue to explore the possible inclusion of other

cryogenic fluids.

A revised work plan for cryogenic fluids was generated by the technical

associates Douglas B. Mann of NBS and T. L. Hillburn of the Phillips

Petroleum Co. representing A.G.A. and API. The scope of the work plan

included instrumentation and procedures for the custody transfer

measurements of pressure, temperature, density, liquid level, flow and

calorific value of liquefied atmospheric and natural (hydrocarbon) gases

having pure fluid or mixture normal boiling points of less than 150 K. Recommendations will be limited to establishing total mass and, where

applicable, total heating value. Fluids and fluid mixtures considered

will be limited to commercially important liquefied atmospheric gases,

atmospheric gases, oxygen, nitrogen and argon and the primary components

of liquefied natural gas, methane, ethane, propane, iso- and normal

butane and pentane.

Flow measurements of pure cyrogenic fluids will be the first of the

recommendations generated under the proposed work plan. This will be

accomplished by combining the existing U.S. and European codes for flow

measurements. A working group has been formed of interested parties and

55
the first draft of this recommendation should be ready for review by

early 1980.

7 . Program and Results .

8. Problem Areas . Staffing caused by press of other programs has caused

some delay and has extended schedule, but does not cause additional

problems

.

9. Level of Effort . July 1 - December 31, 1979

Staff-years expended 0.06

Equipment and/or Services purchased 0.00

Approximate Expenditures $5,000

10. Future Plans . Work will continue to combine the two existing codes.

The codes have been reduced to specific subject elements and the element

common to the two codes has been identified. Conflicting requirements

are being noted and will be resolved by the working group. Requirements

present in one code and absent in the other are also being identified

and inclusion in the combined code will be resolved by the working

group

.

Plans include preparation of the First Preliminary Draft by the working

group.

56
NBS-114A (REV. #-78)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 80-1626

2.Gov*L Accession No,

4. TITLE AND SUBTITLE

LIQUEFIED NATURAL GAS RESEARCH AT THE

NATIONAL BUREAU OF STANDARDS

5. Publication Date February 1980

vV', Mo.

7. AUTHOR(S) 8 . Performing Organ. Report No.

.

j

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, city, State, ZIP)

See page ii

13. Type of Report & Period Covered

1 July 1979-31 Dec. 1979

15. SUPPLEMENTARY NOTES

I | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200-word or leas factual summary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.) The objective of this report Is to:

1. provide all sponsoring agencies with a semiannual report on the activities

of their individual programs;

2. inform all sponsoring agencies on related research being conducted at the

NBS-NEL Themophysical Properties Division, NBS-NEL Mechanical Processes

Division and NBS-NML Fracture and Deformation Division;

3. provide a uniform reporting procedure which should maintain and improve

communication while minimizing the time, effort and paperwork at the cost

center level.

The work is supported by NBS and seven other agencies and represents the

collective expenditure of $676,900 during the 6 month reporting period. The contents

>f this report augment quarterly progress meetings for certain of our sponsors and

rovide a perspective which is missing when the parts are viewed individually,

istribution of this document is limited and intended primarily for the supporting

gencies. Data or other information must be considered preliminary, subject to

change and unpublished, and therefore not for citation in the open literature .

J. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the flret tetter of the first key word unless a proper name;

separated by semicolons)

ryogenics; liquefied natural gas; measurement; methane; properties; research.

ft. AVAILABILITY | \ Unlimited 19. SECURITY CLASS 21. NO. OF

(THIS REPORT) PRINTED PAGES

H For Official Distribution. Do Not Release to NTIS UNCLASSIFIED

Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

20. SECURITY CLASS

(THIS PAGE)

22. Price

Order From National Technical Information Service (NTIS), Springfield,

| VA. 22161 UNCLASSIFIED

i i crOMM- n

r
’