NBSIR 74-358 C^i)

LIQUEFIED NATURAL GAS RESEARCH

at the

NATIONAL BUREAU OF STANDARDS

PROGRESS REPORT FOR THE PERIOD

JULY 1-DEC 31, 1973

D. B. Mann, Editor

CRYOGENICS DIVISION • NBS-INSTiTUTE FOR BASIC STANDARDS • BOULDER, COLORADO

NBSIR 74-358

LIQUEFIED NATURAL GAS RESEARCH

NATIONAL BUREAU OF STANDARDS

D. B. Mann, Editor

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

Progress Report for the Period

July 1 - December 31, 1973

at the

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W Roberts Director
Prepared for:

American Gas Association

1515 Wilson Boulevard

Arlington, Virginia 22209

LNG Density Project Steering Committee

(in cooperation with the American Gas Association)

Pipeline Research Committee

(American Gas Association)

Federal Power Commission

Bureau of Natural Gas

Washington, D. C. 20426

General Services Administration

Motor Equipment Research & Technology Division

Washington, D. C. 20406

U. S. Department of Commerce

Maritime Administration

Washington, D. C. 20235

U. S. Department of Commerce

National Bureau of Standards

Institute for Basic Standards

Boulder, Colorado 80302

U. S. Department of Commerce

National Bureau of Standards

Office of Standard Reference Data

Washington, D. C, 20234
ABSTRACT

Fourteen cost centers supported by six other agency sponsors in addition to NBS provide the basis for liquefied natural gas (LNG) research at NBS.

This integrated progress report to be issued in January and July is designed

to:

1) Provide all sponsoring agencies with a semi-annual and

annual report on the activities of their individual programs,

2) Inform all sponsoring agencies on related research being

conducted at the Cryogenics Division of NBS-IBS.

3) Provide a uniform reporting procedure which should

maintain and improve communication while minimizing

the time, effort and paper work at the cost center level.

The contents of this report will augment the quarterly progress meetings of some sponsors, but will not necessarily replace such meetings. 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to change and unpublished; and therefore not for citation in the open literature.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: Cryogenic; liquefied natural gas; measurement;

methane; properties; research.

iii
Contents

Reference Data

a) Refractive Index- Fluid Methane

b) Fluid Transport Properties

c)

d)

e)

f)

g)

h)

Properties of Cryogenic Fluids - Laser

Scattering Measurements

Properties of Cryogenic Fluids - Equilibrium

Data, Compilation and Evaluation, and Prediction Methods

Survey of Current Literature on LNG and

Methane

The rmophy sical Properties Data for Pure

Components of LNG Mixtures

Densities of Liquefied Natural Gas Mixtures

Low Temperature Material Behavior

II. Measurement Science

a) Heating Value of Flowing LNG

b) LNG Density Reference System

III. Technology Transfer

a) LNG Technology Transfer

b) Federal Power Commission Consultation

c) LNG-Dual Fuel Auto

Cost Center Page

2750122 1 2750124 3

2750141 5 2750142

and

2750145 8

2750362 14

2750364 17

2751364 26

2750430 32

2750361 36

2751361 47

2750401 51

2750404 56

2750590 61

i v
1. Title. Refractive Index of Fluid Methane

Principal Investigator . James D. Olson

2. Cost Center Number. 2750122

3. Sponsor Project Identification . NBS-NRC Postdoctoral Research

Associate Program

4. Introduction . This experimental program will provide accurate

measurements of the refractive index of liquid and gaseous methane.

The data can be related to the fluid density by the Lor entz- Lorenz

electromagnetic equation of state and, as such, offers the possibility

of fluid density gauging by optical techniques. This pure fluid data is

essential to the possible study of mixture refractive index properties.

5. Objectives or Goals . The refractive index of liquid and vapor methane

will be measured along the two-phase saturation boundary. In addition

gaseous isotherms will be obtained at 220 K, 250 K, 280 K, and 300 K

at pressures to 200 atm. Low pressure isotherms will be measured

below the saturation boundary.

6. Background . The high precision interf erometric technique used to

measure the refractive index was developed in this laboratory by D. E.

Diller (J. Chem. Phys. £9, 3096 (1968)). An improved optical data

gathering method was the principal modification of this technique.

Prior to this reporting period, a literature survey of Lorentz- Lor enz

and Calusius- Mos sotti vir ial equation data was conducted. A cryostat

was constructed using the design of Diller.

7. Program and Results . The apparatus was completed in July and

preliminary refractive index isotherms were obtained at 300 K without

refrigeration in the cryostat. These tests of the modified optical

technique were successful. In October, the apparatus was cold-tested

with liquid N2 for the first time. Temperature control problems were

encountered and corrected. In November, vapor pressure measurements on liquid methane indicated thermal gradients were present in

the pressure bomb-guard ring arrangement. These were responsible

for temperature measurement errors of about 40 mk. During

December it was necessary to disassemble the apparatus and redesign

a portion of the guard ring to eliminate the temperature gradient.

Thus far there have been no results.
8. Problem Areas . The temperature mea surement problem was

discussed in section 7. As a consequence, the measurement program

is two months behind schedule.

9. Funding . July 1 - December 31, 1973

Labor 0. 5 MY

Other Costs

Total

Remaining

10. Future Plans.

Jan Feb Mar Apr May Jun

Temperature Measurement

Tests

Measure Refractive Index

Methane

Gas Isotherms

Data Analysis

Repeat Measurements

Manuscript Preparation

>

>

>

>

>

17. 0 K$

1. 5 K$

18. 5 K$

21. 5 K$

2
1. Title. Fluid Transport Properties

Principal Investigator . Howard J. M. Hanley

2. Cost Center Number . 2750124

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

4. Introduction . Studies of mixtures have not received the attention or support that have been given to equivalent studies of pure fluids. This

is especially" true for transport properties where the mixture effort

has been negligible. Yet from the standpoint of the liquefied natural

gas industry mixtures are more important than pure fluids.

At this time there is no adequate method in existence for predicting

the transport properties of fluid mixtures even in the dilute regions.

Properties cannot be measured for all possible mixtures, thus

adequate predictions methods are needed in order 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 include: 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) suggested

guidelines for future areas of experimental work.

6. Background. A program was started in 1965 with the goal of

producing tables of fluid transport properties through many approaches;

e.g. data correlation and evaluation, statistical mechanics, kinetic

theory, thermodynamics and statistics. A theory was developed based

on a modification of the Enskog theory. In addition a systematic study

of inter molecular potential functions was performed which resulted in a new potential function, the M-6-8. The theoretical studies along

with data analysis resulted in prediction techniques for the dilute gas

region for monatomic and polyatomic fluids. These techniques were

then successfully extended to the dense gas and liquid regions. To

date tables of transport properties have been prepared for argon.

3
krypton, xenon, oxygen, nitrogen, fluorine and hydrogen. In addition

an analytical representation of the anomalous behavior of the thermal

conductivity coefficient in the "critical region" has been developed. As

a precursor to the study of fluid mixtures we have started a task to

apply numerical techniques such as molecular dynamics to transport

properties. To this end the Principal Investigator will be spending

the period November 1973 to August 1974 at Australian National

University working with International Authorities in the field, Dr. R.

O. Watts and Professor R. J. Bearman.

7. Program and Results . The mixtures part of the program has not

started as yet. As mentioned above the Principal Investigator is in

Australia gaining experience in advanced theoretical techniques.

During the current reporting period a molecular dynamics model has

been modified and applied to methane. The program has been run

for a system of 108 methane molecules. The resulting output are,

m effect, experimental data and will be compared with methane data

and equations of state from the Cryogenics Division.

8. Problem Areas, There are no problem areas at this time except a financial one, since the level of support is less than what is required

for the project. The projected shortage at the end of FY74 is 12 K$,

which may require a reduction in scope of mixture work.

9. Funding . July 1 - December 31, 1973

Allocation

Labor

Other Costs

50 K$

0. 5 MY

Total

Remaining

OSRD

27. 8 K$

1. 5 K$

29,

20,

3 K$

7 K$

10. Future Plans. During the next six months studies will continue and

the mixture part of the program will begin after August 1974. If the

methane calculations prove successful, it may be possible to make

preliminary calculations on binary systems of methane with ethane

and nitrogen at an earlier date.

4
1. Title . PROPERTIES OF CRYOGENIC FLUIDS:

HYPERSONIC VELOCITY AND THERMAL DIFFUSIVITY MEASUREMENTS

Principal Investigator . G. C. Straty

2. Cost Center Number . 2750141

3 . Sponsor . NBS

4. Introduction. Laser light scattering techniques will be used to obtain accurate thermophysical properties data for corapressed and liquefied pure methane.

This work will complement related work on the thermodynamic properties of the

pure components of LNG mixtures (2751364). This work will provide data for

the development of LNG technology involving density gauging and heat and mass

transfer calculations at NBS and throughout the natural gas industry.

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

sound velocity and thermal diffusivity data for pure methane (90 -300 K, 350 bars)

by using laser light scattering techniques. Sound velocity data are useful for

testing the consistency of volumetric, calo rime trie and thermodynamic properties data for the pure components of LNG, and are potentially useful for LNG

density gauging applications. Thermal diffusivity data are useful for calculating

transport properties of LNG mixtures required for performing heat transfer

calculations.

6. Background . When light is incident on a perfectly homogeneous fluid,

the reradiated (scattered) light field sums to zero in all but the exact forward

direction. For a "real" fluid however , fluctuations, arising through various

mechanisms, destroy the perfect homogeneity and results in the scattering of light

in other directions as well. For example, thermally activated density fluctuations

5
(phonons), propagating with the characteristic velocity of sound, give rise to

scattered light which is doppler shifted in frequency from, the incident light

frequency and whose spectrum contains information on the sound velocity and

attenuation. Local non-propagating temperature fluctuations , which decay

diffusively, give rise to scattered light in a narrow frequency band, about the

incident light frequency and whose spectrum contains information on the lifetime of the fluctuations (thermal diffusivity) . Since the frequency shifts are

generally very small, it was not until the advent of the lasers with their

extremely well defined frequency, that practical experiments using these

phenomena were possible.

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 and under conditions for which sound absorption

is too large to perform ultrasonic measurements; laser light scattering techniques

permit measurements of thermal diffusivities 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 recently been demonstrated.

We have constructed a facility for laser light scattering measurements

of hype rsound velocitie s in compressed and liquefied gases (76-300 K, 350 bars).

The apparatus consists of a copper optical cell with fused quartz windows,

6
cryostat for refrigeration with liquid nitrogen, an argon ion laser, pressure

scajined. Fabry-Perot interferometer, and photon counting equipment. We have

obtained spectra of the light scattered from liquid toluene and compressed gaseous

methane at room temperature previous to this reporting period.

7. Program and Results . Preparations are being made to obtain sound velocity

measurements for pure methane at low temperatures and at low densities (< 14 mol/'t)

where the sound absorption in methane is too large to permit ultrasonic measurements.

8. Problem Areas. No significant problems have been encountered. Progress

on the light scattering experiment has been limited primarily by our arrangement

of priorities to other LNG related efforts. Emphasis has been placed on the

measurement of ultrasonic sound velocity in pure methane. Inability to make

ultra- sound velocity measurements at low density, however, has placed additional

emphasis on the light scattering experiments to obtain this needed data and progress

in this area is expected to accelerate.

9 . Funding .

Manyears Expended, July - Dec 1973 0.2

Equipment cind/or Services Purchased $ 3,942

Total Reporting Period Cost $ 12,122

Balance Remaining (Jan 5, 1974) $ 27,378

10. Future Plans.

year

Schedule: quarter

1974

led

4)

1 2 Methane

:

measure hypersonic (GHz)

sound velocities

7

(completion schedi

for October 197
1. Title . PROPERTIES OF CRYOGENIC FLUID MIXTURES: EQUILIBRIUM

DATA, COMPILATION AND EVALUATION, PREDICTION

METHODS

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

(part time), W. R. Parrish (part time).

2. Cost Center Numbers . 2750142; 2750145

3. Sponsors . NBS; NBS-OSRD

4. Introduction. This project provides compilations of evaluated equilibrium

data and experimental measurements on equilibrium properties which are suitable

for direct technological use or for the evaluation of prediction and calculation

methods. Correlation and prediction methods have, therefore, been of direct

concern in these efforts. This project supports the development of LNG technology in the areas of separation, purification, and custody transfer by defining

relationships between temperature, pressure, and equilibrium state properties

for mixtures related to LNG.

5. Objectives or Goals . The overall objective is to provide critically evaluated data, original and from other sources, on the phase equilibria and thermodynamic properties of cryogenic fluid mixtures. The program has been divided

logically into specific steps as follows:

(a) preparation of a bibliography on experimental measurements

of equilibrium properties for selected molecular species of

principal interest for cryogenics

(b) selection and/or development of methods for prediction,

correlation, and evaluation of equilibria properties.

8
(c) retrieval and evaluation of specific experimental data for

systems selected on the basis of theoretical and/or technological importance.

(d) preparation of guidelines for research based on the deficiencies

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

(e) directing the experimental research effort to alleviate deficienc ies

and provide the basis for improvement of prediction methods

6. Background. A physical equilibria of mixture s research project was

established in the Cryogenics Division in 1959. The initial effort, based on

a bibliographic search and other considerations, was directed toward the

acquisition of experimental data on the solid-vapor and liquid vapor equilibria

and physical adsorption properties for a limited number of binary and ternary

systems of components with widely separated critical points. Most of the

systems studied were those containing 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 new correlation for

the prediction of deviations from the geometric mean rule for combining

characteristic energy parameters. In addition, significant new information

was gained on interaction third virial coefficients which was used in a new

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 in general.

9
The recent efforts have been directed toward problems associated with

systems containing components with overlapping liquid ranges, such as the

nitrogen + methane system.

Up to this reporting period, an expanded bibliography was prepared

to update NBS Technical Note 56 published in May I960 (objective a ). Experimental liquid-vapor equilibria measurements were also completed for

selected temperatures on the argon + methane, nitrogen + methane, nitrogen

+ argon, and nigrogen + argon + methane systems.

7. Program and Results. The progress of this program is summarized

as follows:

(a) A comprehensive bibliography of experimental data for

ten equilibrium properties has been completed and is

presently undergoing editorial review prior to publication.

The bibliography includes sections on solid -liquid, solid-vapor,

solid-liquid-vapor, liquid -liquid , liquid-vapor, and gas-gas

equilibria, as well as sections on liquid mixture densities,

gas or vapor mixture densities. Joule -Thomson coefficients,

and calorimetric measurements. The materials considered are

hydrogen, helium -3, helium -4, deuterium, neon, carbon

monoxide, nitrogen, oxygen, hydrogen sulfide, fluorine, argon,

carbon dioxide, krypton, xenon, methane, acetylene, ethylene,

ethane, propylene, propane, cyclopropane, n-butane, and

isobutane.

10
Because of its importance, the section on liquid-vapor

equilibria was published as a survey paper in Cryogenics 13,

No. 10, 575 (Oct. 1973). It is anticipated that the complete

bibliography will be available by July 1, 1974.

Work is currently in progress on the retrieval and evaluation

of equilibria data for both the argon + methane and the nitrogen

+ methane systems. To maintain this phase of the program

within reasonable bounds, the only properties under study

are liquid-vapor equilibria, liquid mixture densities, and gas

or vapor mixture densities. This effort also requires selection of the pure vapor pressures and saturation densities. The

new vapor pressure measurements of Wagner (Cryogenics,

August 1973) for nitrogen cind argon are being programmed and

evaluated. These new measurements indicate that the argon

vapor pressure temperature relationship given in NBS-NSRDS 27

is in error by 0.04 K.

Our most recent liquid-vapor equilibria data for the nitrogen

+ methane system between 95 and 1 20 K were presented at the

Cryogenic Engineering Conference in Atlanta, August 1973.

These data are also being assessed at the present time to

determine if additional information on the second interaction

virial coefficients might be derived.

11
(d) The development and organization of the LNG technical

sessions for the Cryogenic Engineering Conference held

in August 1973 evolved a considerable contribution of time

and effort.

8. Problem Areas, The major problem that may affect progress on

the evaluation of mixtures data is the lack of generally accepted, rigorous

methods for critically evaluating phase equilibria data. Each binary system

poses special problems of its own, and it may be necessary to tailor the

techniques employed. Generating new experimental data may not be possible

within the next six months due to apparatus commitments for other mixture

data and a lack of qualified manpower.

9. Funding.

Man-years expended (July-Dec 1973) 0.4

Equipment and/or Services Purchased $ 2,529

Total Reporting Period Cost $ 21,750

Balance Remaining (Jan 5, 1974) $ 38,250

12
10. Future Plans,

year

Schedule: quarter

1974

1 2 Retrieve phase equilibrium data

for methane -argon and

methane-nitrogen mixtures

Select pure component (methane,

argon, nitrogen) data

Calculate excess Gibbs energies

for methane -argon and

methane-nitrogen mixtures

Compare calculated excess

Crihhfs enerpip'? for different

sets of data

Compare calculated excess

volumes V"^ for different

sets of data

>

^

>

>

^

\

13
1. Title . Survey of Current Literature on LNG and Methane,

Principal Investigator . Neil A. Olien

2. Cost Center Number . 2750362

3. Sponsor Project Identification . American Gas Association Project BR 50-10

4. Introduction . It is important that all NBS personnel working in LNG

as well as the AGA 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 continuing

awareness of the current publication scene will be 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 three bibliographies

involved: methane properties, methane mixtures properties, and

processes and equipment involving methane and LNG. These three

will be updated each October.

6. Background . In 196 9 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 300 primary publications

and nearly 30 secondary publications. Of these approximately onethird are directly related to LNG. In addition, within the past year

we have increased our coverage of the energy field to include

hydrogen as a future fuel. 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 and

the Liquefied Natural Gas Survey has been published quarterly since

1970.

14
7. Program and Results . Two issues of the LNG Quarterly were

prepared and distributed. There are now 108 subscriptions going to AGA Member Companies and 195 to other subscribers. In September

and October we updated the three bibliographies covering methane

properties, methane mixtures properties and processes and equipment

involving methane and LNG.

For some time we have realized that the above mentioned comprehensive bibliographies had grown to such a large size as to limit their

usefulness (e.g., B-965 covering processes and equipment listed over

1500 references). With this in mind we have reviewed the individual

references in each bibliography and selected those which were most

useful either from the standpoint of accuracy of the data or the

appropriateness of the subject matter. These are now complete and

copies have been printed and are available for sale as listed below.

B-1055 THERMOPHYSICAL PROPERTIES OF METHANE - A

SELECTED BIBLIOGRAPHY, 61 pp, mdexed by property,

phase and author (Sep 1973) $8.00

B-1056 PROPERTIES OF METHANE MIXTURES - A SELECTED

BIBLIOGRAPHY, 94 pp, indexed by property, system and

author (Sep 1973) $10.00

B-1075 PROCESSES AND EQUIPMENT INVOLVING LIQUEFIED

NATURAL GAS AND METHANE - A SELECTED

BIBLIOGRAPHY, 52 pp, indexed by subject and author

(Oct 1973) $5. 00

During the period July through December 1973 we have distributed

75 copies of these and the comprehensive bibliographies.

8. Problem Areas. We have no problem areas at this time.

9. Funding. July 1 - December 31, 1973

Labor 6 . 8 K$

Other Costs 1 . 6 K$

Total 8.4 K$

Remaining 8.4 K$

10. Future Plans. Issue 73-4 of the LNG Quarterly was mailed to the

National Technical Information Service for printing and distribution on January 8, 1974.

15
Jan Feb Mar Apr May Jun

Search of Current Literature

Preparation of Issue 74-1

Preparation of Issue 74-Z

^

>

^

16
1, Title. THERMOPHYSICAL PROPERTIES DATA FOR PURE

COMPONENTS OF LNG MIXTURES

Principal Investigators . R. D. Goodwin, G. C. Straty

2. Cost Center Number . 2750364

3. Sponsor . American Gas Association Project BR 50-10

4, Introduction. This cost center will provide an accurate data base for

LNG mixtures for cryogenic engineering at NBS and throughout the gas industry.

5. Objectives or Goals . The objective of our work is the determination of

accurate, comprehensive thermophysical properties data for the major pure

components (methane, ethane, propane, butanes, and nitrogen) of liquefied

natural gas mixtures at temperatures between 90K and 300K and at pressures

up to 350 atm (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.

Accurate phase equilibrium, compressibility, and thermodynamic

properties data are needed to design and optimize gas separation and liquefaction

equipment such as compressors and heat exchangers. Accurate data for the

pure components of LNG mixtures will permit taking into account the depenence of the thermophysical properties of the mixtures on the composition.

6, Background. Liquefied natural gas is expected to supply an increasing

percentage of the United States' future energy requirements. In spite of the

desire to make the U.S.A. self sufficient in energy resources,

it is likely that we will import all of the natural gas we can obtain during the

years 1976-1985. Ships and importation terminals are being built for

17
transporting, storing, and vaporizing massive quantities of liquefied natural

gas for distribution. Accurate physical and thermodynamic properties data

for compressed and liquefied natural gas 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.

There is little accurate (~1%) phase equilibrium, compressibility, and

thermodynamic properties data available for compressed and liquefied natural

gas mixtures at low temperatures. Natural gas mixtures liquefy at temperatures below -120°F (189 K) , boil at temperatures near -256°F(113 K) , and freeze

at temperatures below -296 ° F (9 1 K). There is little accurate thermodynamic properties data available, even for the liquefied pure components (methane, ethane,

propane, butanes, etc. ) in this temperature range. In addition, the compositions of natural gas mixtures vary considerably from one source to another

and change continuously during transport and storage because of selective vaporization. The introduction of composition as an additional independent variable

adds a new dimension to the scope and complexity of the task of providing an

adequate data base.

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

18
dependence of thermodynamic properties on temperature (at fixed pressures

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

and calorimetric measurements directly on multi component mixtures to

permit accurate interpolation of the data to arbitrary compositions, temperatures and pressures. Instead, thermodynamic properties data for multicomponent mixtures usually must 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 industry with

comprehensive accurate data for pure compressed and liquefied methane,

because methane is the most abundant component (>70%) in LNG mixtures.

Thermophysical properties data for pure methane satisfactorily approximates

data for LNG mixtures in some cases. The project includes acquiring thermodynamic properties data for ethane and the other pure components to permit

more accurate calculations of the dependence of the properties on composition.

We have recently completed a National Bureau of Standards Interagency

Report, NBSIR 73-342, Thermophysical Properties of Methane, From 90 to

500 K at Pressures to 700 Bar , by Robert D, Goodwin. This report is the

final report of our work on the physical and thermodynamic properties of

compressed and liquefied methane and summarizes the results obtained by

R, D. Goodwin, R. Prydz, B. A. Younglove, G. C. Straty, and others of the

Cryogenics Division during the period April 1970 to April 1973. This report

contains the most comprehensive and accurate tables available for the thermophysical properties of pure methane. It gives numerical values for all of the

technically important thermodynamic properties at temperature and pressure

19
intervals small enough for accurate interpolation. The interpolation functions

and computer programs used to generate the tables are also included.

Consistency between the various tabulated properties is as sured, because they

have all been calculated using a single equation of state. Calculated compressibilities, heats of vaporization, specific heats, and sound velocities have been

compared with all of the measured data we could obtain. This report will

provide an accurate basis for calculating thermophysical properties data for

LNG mixtures, in cases when it is necessary to take into account the dependence of properties data on the mixture composition.

We have also completed and published ( Cryogenics , 13 , 712 (December

1973)) accurate dielectric constant and Clausius -Mossotti function data for

pure compressed and liquefied methane. This data will provide a data base

for mass and density gauging,

7. Program and Results .

7, 1 Ethane. Thermodynamic Properties Data -- R. D. Goodwin

In the past six months we have completed and published our work on the

physical and thermodynamic properties of methane [1].

We now are laying foundations for computing tables of provisional values

of thermodynamic functions for ethane. This activity has two purposes: to

indicate those physical properties for which experimental data are lacking or

inadequate, and to provide the AGA with useful results at an early date. The

scope and detailed progress of this work is given in the following List of

Current Reports [2-6].

20
We now are bringing to final form a simplified version of our unique

equation of state [1]. The objective is a form free of redundancies, which is

qualitatively correct in all of its derivatives. It is needed to begin our examination of PVT data for ethane (density and temperature ranges shown in

Figure 1) because the high-density data of A. K. Pal are known to have

systematic errors. More important, our ultimate goal is to provide a basis

for work on mixtures, via an accurate, simple equation of state of identical

form for each of the pure components.

List of Current Reports

[1[ R. D. Goodwin, The Thermophysical Properties of Methane from 90 to

500K at Pressures to 700 Bar, NBSIR 73-342, (Cryogenics Division,

National Bureau of Standards , Boulder, Colorado 80302, October 1973).

[2] R. D. Goodwin, The Vapor Pressures of Ethane, Laboratory Note 73-3,

July 9, 1973. (Unpublished)

[3] R. D. Goodwin, Ethane Virial Coefficients and Saturated Vapor Densities,

Laboratory Note 73-4, Aug. 14, 1973. (Unpublished)

[4] R. D. Goodwin, The Orthobaric Densities of Ethane, Methane, Oxygen

and Fluorine, Laboratory Note 73-5, Sept, 18, 1973. (Unpublished)

[5] R. D. Goodwin, Liquid-Vapor Saturation Temperatures of Ethane and

Methane, Laboratory Note 73-6, Nov. 28, 1973. (Unpublished)

[6] R. D. Goodwin, Unpublished formulations of the melting line and of the

ideal gas thermofunctions for ethane.

7. 2 Ethane, Compressibility (PVT) Data -- G. C. Straty

In the gas expansion technique used in this laboratory for accurate,

absolute, compressibility (PVT) determinations, the molar volume V of a

cryogenic fluid contained in a cell at temperature T and pressure P is determined

by expanding the fluid from the calibrated cell into large calibrated volumes

21
oCD

(X) c

LTi

CD

CD

C3-

OH

CD

CD

CD

CD cQH

ni>

(VaB

(U HC

CD

CD

CO CNJ CO Csl

22
maintained near room temperature (~295K), Using the near-ideal-gas -like

behavior of the room temperature gas, the number of moles of gas residing

in the total system can be computed accurately. One of the factors limiting

the accuracy of this method is the ability to assign correctly the appropriate

proportions of the fluid to the cell and to the various noxious volumes elsewhere

in the system.

PVT measurements on ethane present an additional problem not

encountered with most cryogenic fluids such as methane, oxygen, etc, , because

the critical temperature of ethane (305, 33K) is well above room temperature.

The consequence is that during many of the density measurements

relatively high density liquid ethane will reside in external parts of the system

and cannot be accurately accounted for in the present apparatus without some

modifications.

Plans are underway to modify the PVT apparatus used previously for

methane for use with ethane. Appropriate portions of the apparatus will be

enclosed in ovens or provided with heaters to maintain the temperature of

these parts well above the critical temperature of ethane in the various parts of

the system to be made and accurate PVT data to be obtained.

7, 3 Methane, Sound Velocity Data -- G, C. Straty

The ultrasonic velocities of sound in pure saturated and compressed

fluid methane have been measured at MHz frequencies. Data have been

obtained along the saturation boundary from near the triple point to 186K and

along several isotherms from lOOK to 300K at pressures up to about 345 bar.

The sound velocity data have been combined with the previously measured PVT

23
data to calculate the isentropic and isothermal compressibilities and the

specific heat ratio C /C , Measurements along the compressed fluid isotherms

at temperatures of 21 OK and above were limited to a minimum density ranging

from about 14 mol/1 at 210K to about 10 mol/1 at 300K due to the large sound

attenuation in methane, A manuscript reporting the results of the ultrasonic

sound velocity measurements on methane is in preparation.

delayed by completion of the final report on the thermodynamic properties of

methane.

As mentioned previously, our attempts to obtain velocity of sound data

for methane at low densities by conventional ultrasonic means have been

unsuccessful because of an abnormally large sound attenuation in gaseous methane.

This large attenuation has been observed by other experimenters and has been

attributed to either bulk viscosity or relaxation phenomenon.

We are now attempting to use newly constructed light scattering

spectroscopy apparatus to obtain hypersonic velocity data at the lower densities.

These data, although somewhat less accurate than conventional ultrasonic data,

should be sufficient to verify the accuracy of the PVT data and the sound

velocities obtained by direct calculation from the PVT data.

9. Funding ,

Man-years Expended, July - Dec. 1973 1, 0

Equipment and/or Services Purchased $ 7, 567

Total Reporting Period Cost $66, 207

P V

8, Problem Areas , Work on the thermodynamic properties of ethane was

Balance Remaining (Jan 5, 1974) $28, 532

24
10. Future Plans.

year

Schedule quarter ^

1974

1 2 Ethane:

analyze available physical

properties data

calculate provisional thernnodynamic

properties data

modify and test compressibility

(PVT) apparatus

Methane:

analyze ultrasonic (MHz)

velocity measurements

report ultrasonic (MHz)

velocity measurements

>

>

^

^

>

25
1. Title . DENSITIES OF LIQUEFIED NATURAL GAS MIXTURES

Principal Investigators . M. J. Hiza, W. M. Haynes

2. Cost Center Number . 2751364

3. Sponsor . Consortium of Energy Companies through the American Gas

Association, Inc. Project BR 50-11.

4. Introduction. Accurate density data are needed for liquefied natural

gas mixtures to provide a basis for custody transfer methods and equitable

custody transfer agreements. This project will also provide a data base for

developing accurate methods for mass and density gauging at NBS.

5. Objectives or Goals . The objective of this work is to perform accurate

(0,1%) measurements of the densities of saturated liquid methane, ethane,

propane, butanes, nitrogen and their mixtures, mainly in the temperature

range 90-150K, at pressures to 10 atm. Measurements will be performed on

six pure components, on about 60 binary mixture compositions, and on about

13 multicomponent mixture compositions.

This project will provide accurate density measurements for testing and

developing methods for calculating the densities of LNG mixtures at arbitrary

compositions and temperatures. 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. Methods

for calculating the heating value of a large volume of liquefied natural gas

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

temperature. As the compositions of LNG mixtures vary considerably

depending on the source of the gas and the processing conditions, methods are

26
needed for calculating accurate density data at arbitrary compositions and

temperatures. The accuracy (0. 1 %) of density data is important because of

the extremely large volumes of liquid involved. A systematic error of 1% in

the density is equivalent to an inequity of $15-20 thousand dollars per ship

load of LNG.

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

calculation methods were performed by independent professionals of

established reputation.

A high precision (0.05%) magnetic densimeter (based on Archimedes

Principle) was designed and constructed prior to this reporting period.

Details of this work have been given in previous reports.

7. Program and Results . 1 July 1973 - 31 December 1973

The assembly of the cryostat, the sample holder and its contents, the

magnetic densimeter components (support coils, servo-circuit, magnetic buoy,

constant current source, sensor coils, etc. ), and auxiliary measurement and

control systems (pressure, temperature, sample handling and refrigeration)

was completed during the past six months. Performance testing of the entire

assembly at low temperatures commenced approximately a month ago.

Room temperature tests of the magnetic densimeter were completed at

the beginning of this report period. During the past month several essential

tests of the servo-circuit and associated parts were carried out at low

temperatures. The magnetic buoy was suspended in a stable configuration at

27
1 1 OK in liquid methane and in vacuum with all parts of apparatus in place.

Additionally, the buoy was maintained in support in vacuum, while cooling from

room temperature to 105K, without making any changes in circuitry components.

Only the values of the currents in the coils changed as a result of expected

changes in the magnetic moment of the buoy (approx. 0. 1%/K near room

temp. ).

The ceramic magnetic buoy, presently inside the sample holder, was

ground in the shape of a right circular cylinder with chamfered edges. Its

diameter and length are approximately 0. 2 and 0, 25 inch, respectively. The

ceramic magnet has been plated with a minimum of 0. 002 inch of copper over

its entire surface. The copper is considerably thicker at the edges since the

-5

buoy (after plating) has no chamfered edges. Gold was flashed (2x10 inch)

over the copper surface for protection.

The finished float was observed for defects under a 100 X microscope.

-5

Its length and diameter were determined to better than 5x10 inch using

gauge blocks. Its mass was measured using a microbalance. Thus, the

density of the buoy at room temperature was determined to better than

0. 05%.

Problems with heating in the main coil have been resolved. Water-cooled

copper plates were installed in close contact with each of the faces of the two

layers of aluminum ribbon which comprise the main coil. By passing water

(I5°C) through copper coils soldered to the copper plates the average temperature of the main coil was maintained below room temperature for a

current of 1 amp, (100 watts). Nominal main coil currents for low temperature

28
measurements will be in the range 0. 6 - 0. 8 amp. All of the effort towards

controlling the temperature of the main coil is a result of an attempt to

control its position relative to the sensor coils within 0. 002 mm. Additionally,

for this purpose three 12 inch fused quartz rods have been employed to

support the main coil at its midpoint in the cylindrical axis direction. By

supporting at the midpoint, thermal expansion effects partially cancel. Quartz

is used because of its low thermal expansion coefficient.

Most of the past month has been devoted to performance testing of the

cryostat, the sample holder, the temperature and pressure measurement and

control systems, and the refrigeration system. This performance testing has

been facilitated with vapor pressure measurements on liquid methane at temperatures between 105 and 120K, A summary of the results of these tests

which have led to minor changes in the cryostat-sample holder assembly is

as follows:

(a) Measured vapor pressures (using platinum resistance thermometer for

temperature measurements and a Texas Inst, Co. quartz bourdon gauge for

pressure measurements) have been consistently higher (0, 13 psi, maximum

difference) than the previous results of Prydz and Goodwin^ (the thermometer

reading was lower (0, IK maximum difference) than expected);

(b) We observed a temperature gradient (0. IK maximum difference) between

the liquid in the bottom of the sample cell and that in the vapor bulb (both

measurements were accomplished with the same pressure gauge; sample holder

is colder at bottom); and

(c) The massive sample holder was slow to react to changes in the flow rate of

the nitrogen refrigerant through the heat exchanger at the top of the copper
shield because of the long conduction path between the heat exchanger and the

bottom of the sample holder

Steps taken to resolve these problems have been:

(a) Additional tempering of thermometer wires,

(b) additional radiation shielding between copper shield and sample cell,

(c) additional cooling directly to the top of the sample cell from the top of the

copper shield (this was accomplished by copper braid cables connecting the

sample holder to the shield; previously, cooling by conduction was only through

the copper bellows at bottom of cell),

(d) additional heaters were wrapped tightly around sample holder at each end

at points to intercept the cooling (the primary heater had previously been

located on the central portion of the cell surface opposite the window),

(e) the support rod and electrical lead cable (sensor coils) have been thermally

shorted to the top of the copper shield (again using copper braid cables), and

(f) a transfer line has been installed to continuously feed liquid nitrogen to

the cryostat reservoir.

The results of having incorporated these new features into the system are now

being tested and analyzed,

A progress report was made at a meeting of the sponsoring companies

held in Boulder on 4 December 1973.

Reference

1. R. Prydz and R, D. Goodwin, J, Chem. Thermodynamics 4, 127 (1972),

30
8, Problem Areas. Apparatus changes have been required to reduce the

temperature difference between the top and bottom of the sample cell at low

temperatures, to obtain accurate (0. 02K) temperature measurements, and to

reduce the response time of the sample cell to the nitrogen refrigerant.

Although these changes have delayed performance of density measurements on

liquid methane, it is expected that the pure component measurements will be

completed on schedule.

9, Funding .

Manyears Expended, July - Dec 1973 1. 0

Equipment and/or Services Purchased $20,197

Total Reporting Period Cost $67, 263

Balance Remaining (Jan 5, 1974) $35,002

10, Future Work . year

Schedule: quarter

1974

1 2 Perform accurate density

measurements:

pure components

binary mixture compositions

containing methane

3*

(completion scheduled

for October 1. 1974)

31
1. Title &: Principle Investigators: Low Temperature Material Behavior

- R. P. Reed

i. R. L. Tobler

R. P. Mikesell

R. L. Durcholz

Cost Center Number 27 5 0430

3 . Sponsor Project Identification: Maritime Administration Project

55-300-15-011

Introduction:

Data on thermal and mechanical properties of structural and

insulation materials are essential to facilitate material selection on the

basis of cost and safety. Proper material choice is of major economic

importance for cryogenic containers in the sea transport of LNG

.

5 . Objectives:

The objective of this program is to obtain fracture toughness and

fatigue crack growth rate data in the temperature range 76 - 300 K. These

measurements are being conducted on a series of Fe-Ni alloys and Al alloys.

6. Background:

To construct tanks for sea transport of LNG requires between

500,000 and 7,000,000 pounds of expensive alloys, depending on the type

of tanker chosen. This large-scale consumption of costly alloys demands

very careful material selection to insure economical but safe, storage tanks.

Therefore, since MARAD's goal is to reduce ship costs, it is in their interest

to insure the availability of relevant thermal and mechanical property data to

enable the best possible selection and design.

32
7 . Program and Results :

The materials effort in this program has concentrated on two

areas, a general materials properties assessment and the initiation of an experimental low temperature tensile, fatigue, and fracture study of

candidate materials. The materials properties assessment has included

a compilation of all the fatigue and fracture data on Fe-Ni steels and their

weldments, a collection of ship design data and an analysis of materials in

use, an assessment of the current production and/ or research efforts of

the materials suppliers, an assessment of the current materials requirements

for LNG containers by the American Bureau of Shipping, U. S. Coast Guard,

and the ASME pressure vessel code, and a bibliography of literature containing data on aluminum alloys, non-metallics , and insulation materials.

For the experimental program most of the materials and selected weldments have been procured; specimens have been made for tensile, fatigue

and fracture tests for selected materials; a variable temperature cryostat

has been built; and the experimental procedures have been proofed.

Materials Properties Assessment:

The literature data from some 60 references on the fatigue and

fracture properties of the ferritic Fe-Ni steels (Ni < 18%) has been extracted,

critically evaluated, and compiled. The fracture data in the compilation are

the impact energy; nil ductibility transition, crack opening displacement,

fracture toughness, and dynamic tear tests and their dependencies on temperatures, composition, and heat treating or cold working. Fatigue data include

fatigue lifetime and fatigue crack growth rates at LNG temperatures. The

welding techniques and welding materials used with these steels were also

considered. An assessment of the heat input and effects of stress relief for

the properties of the heat-affected- zone (HAZ) has been compiled. Included are the tensile properties, hardness, impact energies, explosion bulge tests,

and fracture toughness.

33
The entire compilation will be sent as an interagency report and

included in a review article on LNG materials in the open literature. The

literature references are now being collected on candidate aluminum alloys,

non-metallics that have been proposed for structural use, and on insulation

materials. Their extraction and evaluations will begin as soon as the acquisition is complete.

The production and research capabilities of the major suppliers

of LNG structural alloys were also assessed. Direct contact was made with

the research personnel of all the major suppliers to assess what work on

these materials has been done or was in progress. These in-house efforts

indicated are generally low level. We have attended the LNG Materials

Conference at the British Welding Institute and visited Technigaz, Det Norske

Veritas, and The Welding Institute to provide information about the foreign

efforts in LNG materials research. We also have a member of our staff on

the Cryogenic Materials for LNG Tank Applications Committee of the Metals

Properties Council.

Experimental Program:

Test materials of 1 -| -inch thick plate have been obtained for the 3j,

5, 6 and 9% Ni steels and 5083. Plates of Fe-5Ni are being welded by

ARMCO and the Fe-9Ni welding has been arranged with Chicago Bridge and Iron.

Specimens will be made from these materials upon return. All efforts have

been made to have the welds be as characteristic of actual fabrication as possible.

A cryostat for variable temperature control around LNG temperatures

has been designed and built. The experimental procedures, including J integral

test techniques, have been evaluated and prove satisfactory. All the auxiliary

load cells, x-y recorders, oscilloscopes, etc. are functional. New methods

have been devised to monitor the crack growth and crack opening. Tensile

measurements and pre-cracking of fatigue and fracture specimens have begun

and are proceeding routinely.

34
8 . Problem Areas:

Some delay has been experienced in obtaining Fe-9Ni and FeNi alloy thick plate from the suppliers. Currently, we have been assured

that these materials will arrive during January.

9 . Funding:

During this reporting period, about $35, 000 has been spent. This

leaves $1 15, 000 for concentrated research during the next reporting period.

10. Future Plans:

Next 3 months:

The fatigue and fracture toughness properties of Fe-5Ni (heat

treated), Fe - 6 Ni (heat treated) and Fe -9 Ni will be measured at 300, 195, 111

and 76K. Specimens will be prepared for 5083Ai<, Fe-3|-Ni, and Fe-5Ni (welded).

Following 3 months:

The fatigue and fracture toughness properties of 5083 Ai,, Fe3|Ni, and Fe-5 Ni (welded) will be obtained at 300, 195, 111, and76K. A

report will be written describing test results.

35
1. Title and Principal Investigators . Heating Value of Flowing JLNG -

J. A. Brennan and R. J. Richards.

2. Cost Center Number. 2750361

3. Sponsor Project Identification. Pipeline Research Committee (American

Gas Association) PR-50-48.

4. Introduction. This project will draw on information and facilities generated by other sectors of the NBS LNG effort. Thus the calibration of a densimeter used will be traceable to the NBS density reference system being constructed by Younglove under cost center #2751361. Mixture density data produced

under #2751364 by Haynes and Hiza will also provide a necessary input to the

proper interpretation of results.

5. Objectives . The original objective of this program was to set up a LNG

flow facility and to evaluate selected flowmeters in LNG service. In November

1973 the objective was expanded to demonstrate the accuracy of measurement

of the heating value of LNG flowing in a pipeline through integration of state-ofthe-art instrumentation for flow, density and heating value. The expanded

project has been conceived of in a three year time frame. In the first year

individual components will be calibrated and installed in the NBS LNG flow

facility.

6. Background. The need for accurate flowmetering of LNG provided the

original impetus for the work in this program (unpublished NBS Report [1972]^

NBSIR 73-300). Since liquid natural gas may be sold on the basis of heating

value the program was broadened to include the necessary instrumentation for

determining heating value of LNG, this expanded program to commence early

in 1974. The objectives are based on scaling small flowmeters capable of

laboratory testing up to full line size components. Appropriate intermediate

sizes are included with field tests scheduled as part of the overall project.

36
7. Results. A portion of the funding for the program during this reporting

period was designated for the installation of a refrigerator in the LNG flow

facility. The installation has been completed and consists of a bath type heat

exchanger in the flow line downstream of the meters. Figure 1 is a photograph of the flow line that was placed inside the dewar shown in figure 2. Liquid

nitrogen is used as the refrigerant. Constant temperatures can be maintained

in the flow line by adjusting the amount of liquid nitrogen in the heat exchanger.

Tests have been successfully conducted at constant temperatures ranging from

103 to 120 K.

Technical content and planning of this program is determined at meetings

of the PRC Supervisory Committee. At the August 14, 1973, committee meeting discussions were held with a representative from the manufacturer of the

1-1/2 inch vortex meter previously tested in this program. The purpose of

this discussion was to find an explanation for the large bias obtained [NBSIR

73-300]. No explanation could be found so it was decided to verify the meter

K-factor (pulses /gallon) in water at NBS-Gaithers burg, Maryland. It was

decided to determine the K-factor of a 2 inch meter of the same type also. If

the 1-1/2 inch meter K-factor in water were close to the value predicted based

on the liquid nitrogen data then all future tests would be on the 2 inch meter.

The results of the water and liquid nitrogen calibrations are shown in

table 1. Three different meter error values are also shown in table 1. These

values were determined respectively by:

(1) calculating the error between the specified and the actual water

K-factor

(2) correcting the manufacturers K-factor for temperature and calculating the error between that value and the actual liquid nitrogen K-factor

(3) correcting the actual water K-factor to liquid nitrogen temperature

and calculating the error between that value and the actual liquid

nitrogen K-factor.

37
38
39
o ^

in

° ^ ^ -

4J

15 ^ ID

00*

00 00

^ ^ ^

LTl

1—

I

U

u

0)

to

CL,

03GO

CO

cu

f CO o

r--

o

H

O

uuW

in*

en

(SI

w u ^ U O

CO n3 m CO

Oh

in

CO^'

LO

u

CO 0)

^ ^ o

y (U nJ

to -r-i m

^ to

bX)

to(U

CO

1—

I

CL,

in

0)
All of the liquid nitrogen data used in determining the error values was obtained on the NBS nitrogen flow facility [NBS Tech. Note 606, 1971].

The error figure in table 1 (last column) results from the best available

method of predicting meter performance at this time. No conclusive statements can be made about the difference between the two numbers since the

sample size (i. e. 2 meters) is so small. Also the 1-1/2 inch meter is not

made using the same scaling laws as are used with the 2 inch and large meters.

Therefore, conclusions regarding the appropriateness of various K-factor prediction methods must await additional data on other meters. Another meter

will be tested during the next reporting period and the results will be used to

further check the prediction methods.

The measured meter K-factor is shown in figure 3. Each water data

point represents the average of five individual measurements taken over a period of two days. The liquid nitrogen data points are individual measurements, not averages, and were all taken on one day in the liquid nitrogen flow

facility.

The 2 inch meter was also tested in the LNG flow facility with liquid nitrogen and liquid natural gas. Figure 4 shows the results of both the liquid nitrogen

and the LNG tests. Here again each data point represents an individual measurement. In figure 4 the meter performance is shown as a deviation, in percent, as

a function of volume flow rate. The deviation shown is the deviation of the vortex

meter from a turbine meter. The vortex meter was installed in series with the

turbine meter but was several feet downstream. This arrangement does result in

the vortex meter having slightly less dense liquid flowing through it as compared to

the turbine meter. The effect of the density difference results in a positive

deviation between the meters and may account for most of the apparent positive

bias shown in figure 4. Although minor refinements of the data are possible as time goes on and more data are obtained, it is not expected that further data

analysis will materially change the overall results shown in figures 3 and 4.

41
zo•— z »- o ^ • tr »— CD—• o:

»— CM

-< Z

» -J a> O

O

CM

o

CVJ

UJ

t—

—i o o s o

00

00

I- rs. iv9/d 'doiovj X

42
'N0IiVlA3a

43
One minor operational point which must be considered in using the vortex

meter in various liquids is the vortex counting sensor. The meter used in the

tests reported here incorporated a thermistor sensor and it was necessary to

have two thermisters of different electrical characteristics to cover the temperature range of the three fluids - water, liquid nitrogen and LNG. The same

sensor was used in liquid nitrogen and LNG but an adjustment in the electronics

was necessary. This adjustment is easily made but is very important and must

be performed with care.

8. Problem Areas. The amplifier used in the load cell output circuit (weigh

system) of the LNG flow facility has failed, so tests are limited to comparing

one meter to another. Before replacing the amplifier a determination will be

made on the effectiveness of changing the method of read out. If the system

can be upgraded by modifying the present arrangement then the amplifier re- placement will be worked into the modifications.

Flow control at low flow rates continues to be a problem. Better control

could be obtained by changing the flow characteristics of the control valve. If the valve stem and plug are removable a modified unit will be installed.

At this time we do not expect these problems to significantly perturb our

schedule.

9. Funding, (as of 1/19/74)

Man years expended 0. 3 Value of equipment purchased (no major purchases)

Total cost (1973) 35 K$

Balance on hand 0

10. Future Plans . An expanded program designed to incoporate the results

of current experiments into a heating value measurement system for flowing

LNG will start early in January 1974. This expanded program (funded at a 2-man-year level by PRC) has been divided into the following four separate

tasks

:

44
(1) Flowmetering

(2) Densimetry

(3) Calorimetry

(4) System integration

Table 2 lists the expected progress in each task during the next reporting

period.

45
Table 2. Program Schedule

Task First Quarter Second Quarter

Flowmetering 1. Purchase 4" meter,

2. Calibrate 4" meter on

water.

1. Calibrate 4" meter on

liquid nitrogen.

Densimetry

Calorimetry

System integration

1. Purchase densimeter.

2. Assemble calibration

equipment.

1. Secure calorimeter.

1. Install flowmeter in LNG

facility.

1. Calibrate densimeter

statically on pure liquids

methane, ethane, propane,

and nitrogen.

1. Install calorimeter at LNG

facility.

1. Install densimeter in LNG

facility.

46
1. Title and Principal Investigators. LNG Density Reference System - Ben Younglove.

2. Cost Center Number. 2751361

3. Sponsor Project Identification. AGA-LNG-Density Reference System

4. Introduction. The emphasis of the LNG effort of NBS is in providing

technical support to industry in meeting the energy needs of our economy with

natural gas.

The density reference system will evaluate the ability of commercially

available instruments to measure densities of LNG. Density is an essential

measurement in performing total energy content determinations of natural gas

reservoirs. While this effort is oriented towards metrology the output from

cost center 2751364 will provide basic reference data on pure liquids and mixtures which will serve as density standards.

5. Objectives. This research will provide a system for evaluating density

measurement capability of commercially available meters. We will evolve a density reference system capable of generating accurate densities for this evaluation. From the commercial meters we will attempt to select one capable of

performance as a transfer standard in order to provide traceability of accuracy

to field density measurement systems.

The first year will be devoted to construction and testing of the density

reference system. In the second year we will concentrate on evaluation of commercial meters while the final year will involve selection testing and application

of the transfer standard.

6. Background. In early 1973 a proposal was made to the American Gas

Association for research in several areas of LNG technology to be done at this

installation. Part of this program was the density reference system. Initital

scheduling indicated for the first year of work, starting in April to be design,

fabrication, and testing of a density system. Work actually commenced in

August as a result of staffing difficulties. Since this initiation, we have conducted extensive study on the feasibility of various techniques for such a system

47
deciding finally on an application of Archimede' s principle (see 7. below). Construction has begun on the various components of the system and the automatic

weighing head plus a precision gas balance for mixture determination are on order.

7. Program and Results. After an extensive study of various methods of

density measurement the approach was chosen of using the results of the Densities

of Liquefied Natural Gas program (cost center 2751364) as primary source densities. A density monitoring device to be installed in the actual density reference

system will provide a more immediately available source of accurate densities.

The performance of the density monitor will be evaluated using the results of

the NBS Densities of LNG program as they become available. The density monitoring device will be a weight by immersion device (Archimede' s principle). The

3 weight of a piece of single crystal silicon (density 2. 32900 g/cm at 25° C and

1 atmosphere) will be determined for the conditions of no buoyant force (vacuum).

For the temperatures of interest this will be used with the weight of the silicon

in the actual test liquid and with the computed density of silicon under the appropriate temperature and pressure to determine the density of the liquid mixture.

The device or devices under evaluation will be immersed in the same

liquid at the same time and in close proximity to the density monitor. A measurement of temperature, pressure, and mol fraction of the constituents will allow

computation of density from the NBS Densities of LNG program. The continuous

reading of monitor weight will signal the attainment of equilibrium.

Accurate measurements of density will also require several auxiliary

parameters be measured such as temperature, pressure, and volume of the gas

spaces above the liquid.

Work has started on parts required for the construction of the density

reference system. An accurate and automatic weighing head for the density

monitor has been ordered. This weighing head should have an overall accuracy

of 0. 001 gram and a dynamic range of 20 grams. It will be self-balancing and

have an automatic readout. Internal counterbalancing will allow the silicon

crystal to be 125 grams.

48
A weight loader has been built which will allow loading known weights

onto the density monitor balance under actual operating conditions so that its performance can be periodically verified. The loader will also allow loading

onto the balance, two weights of equal mass but different densities so that the

gas density in the volume about the balance, can be measured. This is one of

the auxiliary variables necessary in accurate density determination.

A high precision gas balance, needed for preweighing of the constituents

of the test mixture, has been ordered. This balance is capable of weighing

50 kg to high accuracy.

"We have been in contact with several field densimeter manufacturers who

will be providing meters for our evaluation and expect delivery of the first meters

for testing soon.

8. Problem Areas. As mentioned under 6. above work began late on this

project and the principal investigator has now completed six months of w-ork on

it. At this point we see some minor delays caused by long delivery times of

some purchased equipment, but within the usual uncertainties of prediction of

research task duration, we feel that the originally propos ed first year objectives

will essentially be met by 1 August 1974.

More serious is the fact that the construction of the density reference system appears to be costing more than originally estimated. Thus, based on the

current costs in 9. below and our projections, we feel that our expenditures in

the next six months will bring the total to between S80, 000 and S85, 000 instead

of the original $60, 000 estimate for the first year's work. Apart from the usual

inflation rate this is probably due to the need to build a slightly more sophisticated apparatus than originally envisioned and to unforeseen purchase costs,

primarily the high precision gas balance, the cost of which ($9624) is being

shared equally with cost center #2751364.

49
9. Funding . (as of 1-19-74)

Man year expended 0. 5 approx.

Value of equipment purchased 7, 900

Total Cost 37, 358

Balance on hand 22, 642

10. Future Plans . First three month period. Continue construction of cryostat, sample holders, cooling system, vapor pressure system, temperature and

pressure measuring systems and associated measuring systems. Construct container for the weighing head. Take delivery of weighing head. Test density monitor balance with silicon weight in liquid water to verify behavior in liquid of

accurately known behavior.

Second three month period. Complete construction of cryostat cooling

system, etc. Depending on progress made at this time, make preliminary test

of monitor with liquid nitrogen.

50
1. Title. Liquefied Natural Gas Technology Transfer

Principle Investigator . D. B. Mann

2. NBS Cost Center . 2750401

3. Sponsor Project Identification . Maritime Administration, Project

55-330-15-011.

4. Introduction . The NBS support of the Maritime Administration

(MarAd) LNG ship program is divided into two areas under a common

contract. These are an experimental program (NBS Cost Center

2750430) and the subject cryogenic technology transfer. In addition

to those objectives listed below this program provides a cohesive

structure for the coordination of the NBS LNG program.

5. Obj ectives . Cryogenic Technology Transfer is designed to provide

cryogenic technical information, data, and advice to the Maritime

Administration (MarAd), its contractors and other agencies performing work of interest to, or for, MarAd in the design, development,

testing, construction and operation of LNG ships and ship components.

6. Background. The Merchant Marine Act of 1970 restructured federal

maritime policies to make bulk carrier vessels, such as tankers and

LNG ships, eligible for construction and operating subsidies. In

December 1973 the keel was laid for a 926 foot long LNG vessel

carrier at Quincy Mass, The keel laying initiated the construction

of the first LNG tanker to be built in the United States. American

ship builders have orders for a total of 13 of these complicated ships.

Various future projections indicate a total of from 25 to well over a 100 ships will be required to handle LNG importation within the next

10-15 years, LNG marine technology is presently foreign dominated.

As a matter of fact, many of the ships being constructed in U, S.

shipyards are using designs under license from foreign industrial

51
groups or governments. LNG is a cryogenic fluid and the raassive

technology developed over the past 15-20 years in cryogenics as applied to industrial gases and the aerospace effort provides a resource

which could be applied profitably to improving the U, S, competitive

position in the construction and operation of LNG shipping. Because

of its historical association with broad based cryogenic technology over

a period of 20 years, the NBS Cryogenics Division was requested to

provide support to the MarAd LNG ships program in order to aid in

the transfer of cryogenic technology, where it could enhance the effectiveness of maritime LNG shipping. Therefore, on April 17, 1973

we submitted a work statement which was confirmed by the establishment

of a program in May,

7. Program and Results, (1 July to 3 1 December 1973) In the initial

phases of the LNG Cryogenic Technology Transfer program emphasis

was placed on establishing the level and degree to which we could interface with MarAd, MarAd research centers (NMRC), and MarAd contractors. Progress therefore is measured as specific responses to

MarAd and MarAd contract requests and NBS generated output felt

necessary for the overall program.

7. 1. Data and Information - LNG. In order to establish the degree

of existing knowledge in this specialized field of LNG, a series of

literature searches have been made utilizing the NBS Cryogenic Data

Center Data Retrieval System. This system contains over 80,000

references on cryogenic subjects. Searches of this reference system

have resulted in six bibliographies on the properties of solids, a bibliography on liquefied natural gas processes (general), a bibliography

on liquefied natural gas processes (selected subject matter), a bibliography on methane and a bibliography on methane mixtures. (See

references 1-10)

52
These bibliographies reflect the state of the art (to 1973) of

liquefied natural gas and are the logical first step in establishing an

LNG information center.

7.2. Mass Gauging of Spherical LNG Storage Containers. We were

able to establish, in this particular case, a parallel objective to a

existing NASA sponsored program for the gauging of total mass of a cryogenic fluid contained in a spherical cryogenic vessel. The technique being explored for NASA involves exciting the cryogenic container

at rf frequencies and observing the change of the resonant modes with

amount of mass contained within the vessel. The first step in applying

this technique to maritime LNG ships was the obvious one of scaling.

Therefore a simple experiment utilizing a dry empty 50 -foot diameter

liquid oxygen tank was conducted. On the basis of the results of these

tests, it was suggested that this device has the potential of being easily

added to existing tanks for both primary and backup gauging,

7. 3. Consultation, Consulting and advisory services are provided

whenever needed, and we have the advantage of drawing on a variety

of capabilities and experience, on short notice, for problems of

limited scope. Examples of such services provided during the re- porting period are (a) data and comments on a MarAd-AiResearch

Corporation contract for "Maritime Closed Gas Turbine Engine Program", (b) Data, opinions and com.ments on M!ar Ad-Booze -Allen

Applied Re search "LNG Technology and Transport Study". NBS provided a review of a portion of the contract involving risk analysis of

second generation LNG ship designs, (c) Establish contact and a basis

53
for a working relationship with the National Maritime Research

Center-Galveston, Texas, Exchange visits of personnel from Boulder

and NMRC -Galve ston were made in August and September and a continuing dialogue is being maintained with NMRC staff to aid in their

definition of program objectives, (d) Maritime Research Information

Service, we are presently providing input to this service from our

Cryogenic Data Center.

referenced progress report to MarAd, In addition, included in the

progress report was a section outlining future activities within the

present contract and a suggested scope of work which may be extended

beyond the current contract period. This section is therefore a result

of information developed since May 1973 which more clearly defines

the position of the NBS Cryogenics Division within the MarAd program

and should be considered as a guide to the content of our contributions

in the near future. As indicated the progress report is presently under

review by the Maritime Administration.

8. Problem Areas. Major problem area under this program is the definition of content and scope, MarAd has a number of separate current

advisory studies, the results of which are necessary for defining their

position in the LNG marine technology. Until these decisions by MarAd

are made, NBS will continue to provide information and assistance of

the type outlined above.

9. Funding . July 1 to December 31, 1973

Details of these responses by NBS are documented in the above

Labor

Other Costs

$ 31, 0 K

5. 0 K

$ 36. 0 K

Remaining $112.0 K

54
Future Plans. The purpose of the progress report issued in December

was to define present level of effort and to suggest a structured future

plan for the period 1 January to 30 June 1974. As a result no definite

schedule for this period is possible until a response from MarAd is

obtained.

55
1. Title and Principle Investigators : Federal Power Commission Consultation -- D. B. Chelton and A. F, Schmidt.

2. Cost Center Number ; 2750404

3. Sponsor : Federal Power Commission - Bureau of Natural Gas -- Letter

agreement dated 4 June 1973.

4. Goals : The Cryogenics Division will provide consultation and advisoryservices to the Federal Power Commission on the cryogenic safety and

the design aspects of several current applications before the FPC for

authorization of LNG terminal and storage facilities. These services

cover properties of cryogenic environments, insulation systems, cryogenic

safety, thermodynamics, heat transfer, instrumentation and cryogenic

processes such as refrigeration and liquefaction,

5. Background : Cost Center initiated July 7, 1973.

6. Program and Results : The results and status of thos e facilities presently

under the jurisdiction of the Federal Power Commission and subject to our

review are outlined in the following table.

Elements of the facilities that are subject to review are the land-based

cryogenic storage tank components, bounded by the tanker or barge,

the vaporizer and the liquefaction units (if any). These include, but are

not limited to the transfer lines, the storage tanks, the vaporizers and the

process piping as it interacts with the storage tanks. It is essential that

the reviews cover the operation, maintenance and emergency procedural

philosophies for each terminal. Based upon these studies, reports are

submitted to the Staff of the FPC setting forth the technical evaluations

and conclusions on each proposal. In addition, NBS may provide expert

witnesses on behalf of the Staff of the FPC in any hearings on the aforementioned applications.

Emphasis is placed on the safety aspects of the facilities including their

possible interactions with the surrounding areas. The impact of engineering design such as appropriate use of existing technology and material

selection for structural integrity must be assessed. The basis of review

includes various codes and standards, prior experience, precedent and

engineering knowledge.

A News Release issued by the Federal Power Commission entitled "FPC

Authorizes East Tennessee Natural Gas to Build $10 Million LNG Facility"

is attached.

56
7. Funding ; Total Funding FY 74 $57,000

Expenses July 1 - December 31 , 1973 $20,000

Man Years of Effort 0. 3

8. Future Plans. At the present time there are several pending

applications, but information is not yet available. It is anticipated

that additional facilities will be reviewed as applications are made

to the Federal Power Commission.

57
FEDERAL POWER COMMISSION

RELEASE WASHINGTON. DC. 20426

IMMEDIATE RELEASE

JANUARY 7, 197 4

Docket No. CP73-336

East Tennessee Natural Gas Company

No. 19952

FPC AUTHORIZES EAST TENNESSEE NATURAL GAS TO

BUILD $10 MILLION LNG FACILITY

The Federal Power Commis sion has issiicd an

order authorizing East Tennessee Natural Gas Company,

of Knoxville, Tenn. , to build a $10, 045,000 liquefied

natural gas plant with an above-ground storage tank and

related facilities.

The plant, to be located near Kingsport, Tenn. , is

designed to liquefy 5, 500, 000 cubic feet of natural gas daily

for storage in a holding tank with the capacity equivalent of

1.2 billion cubic feet of gas and send-out design rate of

100 million cubic feet daily. A new 1, 100 -horsepower gas

turbine compressor will be installed at a new compressor

station near Bristol, Tenn.

East Tennessee plans to use the LNG facility to

provide an interim and long-term supplemental winter

service to its existing customers, beginning this winter.

Pending completion of the storage facility, the

company has arranged to provide an interim supplemental

winter service by using Chattanooga Gas Company's existing

LNG storage facility during the 1973-74 and 1974-75 winter

heating seasons. Chattanooga is a customer of East

Tenne s see.

The project will convert, by use of the LNG facilities,

summer valley gas from Tennessee into LNG that can be

readily stored during the summer months for subsequent

regasification and delivery during the winter heating season.

It can then be made available for high priority uses by

existing customers.

58

(over)
No. 19952

The Coramissicn said it recognized that there is

potential danger tc the p^ibiic associated with storage and

handling of I-,NG, as there is ^-ith other flammable liquids

and gases. However, it said, for this particular facility

in this particular location, the risk to the public's safetyis not considered significant.

The National Bureau of Standards, under FPC

contract, concluded that the proposed facilities constructed

and operated in the manner set forth in the application "can

reasonably be expected to function safely. " In addition,

NBS said that "ail practicable care has been taken by

East Tennessee Natural Gas Company and its contractors

in designing a facility embodying sufficient safeguards

(including appropriate fire protection and prevention

systems) tc eliminate or reduce to acceptable levels the

impact of credible accidents."

The Ccmmiission said that an independent assessment

by its own staff indicated that the type of accident that would

expose the general public to greatest danger would be the

quick release of all stored LNG to the diked area around

the tank which, under unique meteoroligical conditions,

could result in an ignitable plume of natural gas extending

about a mile.

However, the Commission said, this would appear

to be an extremely unlikely event. No cryogenic tanks of

this type have ever failed in this manner and it is difficult

to postulate ho-v such a failure would occur, the Commission

said.

However, to reduce this extremely low risk even

further, the FPC is requiring East Tennessee to develop

accident contingency plans, to file various safety reports

with the Commission^, and to comply with all pertinent

Federals State, and local safety regulations.

-FPCFor further iniormation

call 386-61 OZ (Area Code 202) DC-114
(0 cn cn cn

0) OJ (U (U

(0 (fi cn cn cn

0) 0) <U 1) d)

(U 1)V (U o u (J t,l o p ^ pH fx ro ro TO ro ro b E b 0, ft Hi Oh CU 0 0 0 0 o o

(J {J (J (J (J (J c c C

C c

T) XI

ro ro ro ro ro ro (U CD (

'd "d

ro 'O T3

f\] (NJ ro ro (NJ (NJ

u d) -C 00 cn (J CJ C/5 ''''

ro ro CO ro

(U r- £^

~' CO X3

(NJ ro (NJ (NJ CU

c^T CJ w

^1 .M

CJ • H

(U Cm d (U lef (U

(L> OJ d) (LI (U cr d)

d 1)

a 1- cu

_j

d) 'dl

^^ tH ^< t< cr cru t< tr Si

!-l l-i t( ti ^^ ^^ i< 0) tti (^ Q ni nt Q

(fl nl ct! (li X! ,Q -D ^ -Q Q XI -Q -Q X) Q

M

O o o o o U o o O

OO o o O o o o o :^ o U o U O O o U o o O o o o o o o o O o o o O o ^ o o 00 00 o O o 00 O o o ro * o o o

ro ro o ro o o fO o r in ro (NJ ro c C C s s

^. s^ d) d) d) H H

4-»

t-i !-i t< 0 0 0 a a S H s

W)

M

a c C > '> '>

(S ni ni X

CO CO^

(Ti ni ni

0) d)

fin ^ < . o 3 f Z m ^ o

d)

cn(n o

dJ (J CC cn d) ni Eh O

cnni

O

W

ni

ni ni C C s B B

M

C

u

CC

d) d) '>

d) '> '>

H

H niH n) ni

X

CO CO CO

t< 0 0 ^ o a ni a ni ni B B

d>

B

aj dJ ft ft ft

(U

r-Hd

d)

(U (I 5 Z

60
1. Title. LNG - Dual Fuel Auto

Principle Investigator. J. M, Arvidson

2. Cost Center Number . 2750590 (Reimbursable)

3. Sponsor Identificaton. Joint NBS and General Services Administration Requisition Number 0F4KE023, Case Number 66551.

4. Introduction. The work described relates to the general area of

transfer of technology based on Division experience in the handling

of liquefied combustible gases, instrumentation and systems analysis,

5. Obj ective . To establish the degree of hazard to passengers and auto

on the release of liquefied natural gas in the trunk area of the standard

GSA dual fuel (natural gas and gasoline) sedan,

6. Background . The General Services Administration (GSA) dual fuel

automobiles are equipped to run on gasoline or natural gas. In the

initial GSA program the natural gas was compressed and carried in

high pressure cylinders, which in sedans were located in the trunk

space. To take care of accidental leakage, a large vent was installed

in the roof of the passenger compartments, with two small air vents

installed in the top of the trunk space. More recently, most of the

dual fuel installations have been installed with liquefied natural gas

(LNG) carried in an insulated tank at low pressure in the trunk compartment.

Natural gas has a density less than air and therefore is buoyant

and will rise at temperatures above about 15 1 K. It was anticipated

that vents provided would be adequate for dilution of explosive concentrations of methane gas in the trunk and passenger compartments

under conditions of operation. This was believed to be the case even

if very cold gas was vented (at a temperature of less than 157 K) as

the amount of the methane gas vented at this lower temperature would

be minimal, would be heated rapidly above 157 K and then vented

normally.

61
A recent explosion of a sedan, believed to be caused bymigration of methane gas from a trunk area to the passenger area -

raised the question of the functional adequacy of the high level vents.

In other words, can a combustible mixture of cold methane gas (at

a temperature of less than 157K) migrate from a leakage area in

the trunk to the passenger compartment, and if so, can additional

venting, relocation of vents, or other methods be incorporated in

the sedan to eliminate this hazardous situation?

GSA has requested the Cryogenics Division of NBS to perform

tests, analyze data, and make recommendations for the modification

(if any) to be made in the vent system or any other aspect, method

or design that would minimize the concentration of methane gas (or

LNG vapor) in the trunk or passenger area to well below the lower

explosion limit (at least to 50% LEL),

7. Program and Results . (1 July - 31 December 1973) In response

to the request from GSA a work statement was prepared on September 7, 1973 and an inter-agency agreement between NBS and GSA

was authorized by GSA on the 4th of October 1973.

On September 26, 1973 a GSA furnished dual fuel automobile

was delivered to NBS Boulder. The vehicle was a 4-door sedan,

license number Gl 1-50627. The vehicle was driven from San Diego,

California by Mr. Cruz J, Avila, who is maintenance manager of

the San Diego Motor Pool. The vehicle had 33,933 miles on it and

was in good condition.

Two modifications were made to this vehicle on the LNG system

that are unlike the accident vehicle: (1) a fill and vent line connection

cap with a plastic tube vent to outside the vehicle and (2) the air cleaner

62
for the engine has been placed on the opposite side of the engine

(right) and the intake duct has been extended. This was done in order

to make room for the additional valves and switches included in the

modification kit.

Prior to testing, the car was placed in an outdoor test site. The

windshields (front and back) were removed; battery was removed;

side v/indows were rolled down; the vehicle was electrically grounded;

and all openings were sealed with a double layer of approximately

6 mil plastic. The gas tank, LNG tank and carburetor were emptied

and purged with gaseous nitrogen. The roof vent of the vehicle was

shielded from minor air currents by a four-sided box (open at the

top). It was shown during the tests that the placement of this shield

had no influence on the experimental data. A purge and methane

injections system was designed to provide a precise flow of methane

into the trunk area. To initiate the test, a pre - deter mined amount

of methane, at various flow rates and temperatures (ambient, 200 K

and 121 K) was released into the trunk space at the fill-vent line

location and allowed to diffuse into the rest of the vehicle. A combustible gas detector, thermocouple power supply, recorder and other

instrumentation were located in an instrument shack approximately

20 feet from the test car. Sample tubes from within the vehicle were

run to the combustible gas detector. These tubes consisted of copper

tubing (3/8-inch diameter) in 50 -foot lengths to insure that all sensing

points had equivalent response times. Eight sample points were

located within the vehicle on a plane running through the vertical

center line. Samples were taken above the front seat at roof level,

at chest level in the front seat and at floor level in the front seat.

Additional samples were taken at the inlet to the roof vent, chest

level of the back seat and floor level in the back seat. Two sensors

were located in the trunk area, one at floor level and one above the

LNG tank.

63
All sensing locations were equipped with thermocouples at

approximately" 1/4-inch from the inlet end of each tube. They were

installed primarily for low temperature methane testing to determine

whether the cold gas migration will occur at floor level. As each test

progressed, a strip chart recording of the gas concentration and temperature was made. A liquid nitrogen cooled heat exchanger was used

to pre-cool the gaseous methane for low temperature tests.

Calibration of the combustible gas detector was performed as

recommended by the manufacturer and, in addition, by use of a water

displacement, 5% mixture of methane and air (100% LEL). At periodic

intervals throughout the entire testing program, both methods of calibration were employed to insure instrument reliability.

Detailed results of the testing have been compiled in a preliminary

progress report that was sent to the sponsor (GSA) on December 21,

1973. In summary, three flow rates of methane (0. 5, 0. 24, and 0. 15

scfm) were introduced into the vehicle in the trunk area at the fill and

vent of the LNG tank. In each case, a total volume of from 8 to

15 scf of methane was used. These flow rates were repeated for three

different temperatures (ambient, 200 K and 121 K)

.

As a result of these tests, it was shown that hazardous conditions

can exist at various locations within the vehicle; their degree depending on variables such as methane flow rate, total volume of gas released,

vehicle disposition (stationary or moving), etc. For most cases the

LEL was reached quickly. After the flow of methane was stopped, the

concentration rate of decay was very slow. It was surprising to note

that for some tests over 40 minutes was required for the concentration

level of methane to fall below the LEL. No significant differences

were found between the circulation and diffusion characteristics for

ambient, 200 K and 121 K methane. Within the limits of reproducibility

64
the test results at all three temperatures may be compared independent of methane inlet temperature. Thermocouples located at

the sensing points also show essentially no change in temperature

within the test vehicle.

Review of the progress report by the sponsor is still in progress.

8. Problem Areas. It was assumed that the most hazardous condition

under which the vehicle would operate with liquefied natural gas as

a fuel would be when the vehicle was stationary and closed (windows,

doors, etc. ) for an extended period of time. Although the reproducibility of the tests was remarkable, it was determined that slight

wind conditions in the neighborhood of the car could effect the test

results. Future testing in a controlled environment should improve

test reproducibility.

The method of sampling the car interior for combustible gas

mixtures involves continuously removing the sample during the

period of test. This was a function of the particular type of combustible gas analyzer used in the test. A combustible gas detector

having the sensor detectors located at the sample point has been

ordered and received, but the testing of this method of sampling has

not been completed at this date. A comparison should be made to

show the validity of the sampling technique.

9. Funding . This was a cooperative effort between the National Bureau

of Standards and the General Services Administration.

Labor $ 8. 5 K

Other 2. 5 K

$10. 5 K

10. Future Plans. Preliminary discussions with the sponsor indicate

that they desire to cantinue the investigation and a program is being

outlined to improve the venting characteristics of the sedan.

65
NBS-ir4A (REV. 7-73)

U.S. DEPT. OF COMM.

RIRI inCPAPHir DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 74-358

2. Gov't Accession

No

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Liquefied Natural Gas Research at the National Bureau

oi oud.nQa,ras

5. Publication Date February 1974

6. Performing Organization Code

7. AUTHOR(S)

D. B. Mann (Editor)

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS , Boulder Labs

DEPARTMENT OF COMMERCE

Boulder, CO 80302

10. Project/Task/Work Unit No. 2750401

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

See reverse side.

13. Type of Report & Period Covered

Progress Report

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most sigriificant information. If document includes a significant

bibliography or literature survey, mention it here.)

Fourteen cost centers supported hy six other agency sponsors in addition to

NBS provide the basis for liquefied natural gas (LNG) research at NBS, This integrated progress report to be issued in January and July is designed to:

1) Provide all sponsoring agencies with a serai -annual and annual report

on the activities of their individual programs, i 2) Inforra all sponsoring agencies on related research being conducted at

the Cryogenics Division of NBS-IBS.

3) Provide a uniform reporting procedure which should maintain and | improve communication while minimizing the time, effort and paper [ work at the cost center level.

The contents of this report will augment the quarterly progress meetings of

some sponsors, but will not necessarily replace such meetings. 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.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Cryogenic; liquefied natural gas; measurement; methane, properties; research.

18. AVAILABILITY I Unlimited

I X For Official Distribution. Do Not Release to NTIS

I

' Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CH

I

^ Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

USCOMM-DC 29042-P74

<r U.S. GOVERNMENT PRINTING OFFICE: 1974 _ 78 4-574 / 1252 REGION NO. 8


12. Sponsoring Organization Name and Complete

Addres s

American Gas Association

1515 Wilson Boulevard

Arlington, Virginia 22209

LNG Density Project Steering Committee

(in cooperation with the American Gas Association)

Pipeline Research Committee

(American Gas Association)

Federal Power Commission

Bureau of Natural Gas

Washington, D. C 20426

General Services Administration

Motor Equipment Research & Technology Division

Washington, D. C. 20406

U. S. Department of Commerce

Maritime Administration

Washington, D. C. 20235

U. S. Department of Commerce

National Bureau of Standards

Institute for Basic Standards

Boulder, Colorado 80302

U. S. Department of Commerce

National Bureau of Standards

Office of Standard Reference Data

Washington, D. C. 20234