Flow Measurement By Insertion Turbine Meters
Author(s): John C. Boykin
Abstract/Introduction:
The value of hydrocarbon products today is increasing at an unprecedented rate. The importance of accuracy in measuring these products is, therefore, becoming more critical. In addition, the cost of construction and operation has increased dramatically. The demand for the products is steadily growing. The higher demand level is forcing new construction and the increase of throughput capability in existing facilities. Existing transmission and distribution lines are being looped and/or packed. Additional cross-country lines are being built. The construction of new loading and storage facilities has generated the need for many miles of relatively large lines (4 inches through 48 inches). New regulations require the measurement in flare stacks and effluent lines, as well as the provision for leak detection on large cross-country hydrocarbon product lines. Natural Gas transmission companies are likely to be required to add odorant to their gas in areas where they pass through or near towns or cities. The costs of hydrocarbon products and water have produced an added interest in the measurement of internal plant utilities for accounting purposes. In short, there is a need for improved measurement techniques.
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Document ID:
82A2DA9F
Fluid Flow Measurement The Annubar Way
Author(s): Norman A. Alston
Abstract/Introduction:
The statement flow measurement denotes the requirement to measure a fluid flow rate for a particular process or application. The quantity and type of measurements required are more numerous than you may imagine, for flow measurement is required at a multiple of points in every industry, plant process, and geographical location for every type of fluid, liquid, or gas. The type of flow measurement device required for each application is in like manner related to need, such as 1. critical nature of process, 2. control functions, 3. economics, and a variety of other guiding parameters. This never ending flow measurement instrument requirement inspires periodic emergence of more and better measurement devices, some of which are quite ingenious.
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Document ID:
6B9A3FD6
Chart Processing
Author(s): Richard A. Manson
Abstract/Introduction:
Many individuals not familiar with the details of chart processing may feel that the basic methods have not advanced as they should. However, I am sure that those involved in chart processing feel that significant strides in the areas of accuracy and efficiency have been achieved. The intent of this paper is to present some concepts of accurate and efficient chart processing and the role of the office and field in chart processing. Since many of these concepts relate to Columbia Gas Transmission Corporations chart processing operation, I feel the following background will be helpful. The chart processing office receives approximately 17,000 orifice and auxiliary instrument charts each month from approximately 4,200 meters. These meters are located in a seven state operating territory and vary from a 2 tube with a .250 orifice to a 20 tube with an 8 orifice. We have 24 hour, 24 hour DOG, 72 hour, 7 day, 8 day, and 31 day chart drives on Foxboro and Barton Gages. The meters measure production, purchase, storage, wholesale sales, and company use volumes. Chart processing equipment consists of UGC Analog Scanner with Foxboro Scan Head, UGC Digital Scanner with Foxboro and American Meter Scan Head, two UGC Chart Analyzers, two Rockwell Integrators and two UGC Electronic Chart Averages. Chart data entry is via IBM 3740 Data Entry System, and calculation and billing are performed on an IBM 360 Model 40 128K. In addition, approximately 4,000 orifice charts from large volume supplier purchases are audited each month.
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Document ID:
02527DEF
Sonic Nozzles
Author(s): Charles L. Britton
Abstract/Introduction:
The terms sonic nozzle, critical nozzle, choker nozzle, and critical venturi are synonymous terms describing the same flow device. The proper usage of the term nozzle should be used when describing a converging device. Likewise, the term venturi should be used when describing a converging/diverging device. However, common usage over the past several years have intermingled the two terms (nozzle and venturi) until they both describe the same device. The operating principles of sonic nozzles have been known for over a century. However, it has been during only the last 10-15 years that sound design parameters have been developed. In the early 1960*s, Smith and Matz 1* and Stratford 2 put forward design parameters that had excellent theoretical foundations. In 1973, reference 3 was published which gave experimental verification of the theoretical solutions put forward by references 1 and 2. The effect of these three papers is that design criteria for sonic nozzles have been established. Figure 1 gives the design criteria from which most of the experimental data of reference 3 was obtained. To date, the standards organizations, such as The American Society of Mechanical Engineers (ASME) or the International Standards Organization (ISO), have not formally accepted a design for the sonic nozzle. Reference 4 gives a design that is similar to that shown in Figure 1. Whenever the formal design is accepted by the standards organizations, it will probably be very similar to that shown in Figure 1.
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Document ID:
09E7D470
Effect Of Pulsation On Gas Measurement
Author(s): W. H. Isner
Abstract/Introduction:
Flow measurement under pulsative flow conditions has been a subject of extensive research and experimental studies for many years. While many of these efforts have added to the state-of-the-art, there is as yet no complete solution available. A common term, pulsation, is the variation in flow or pressure occurring in the fluid under consideration, or as normally understood, a pressure wave created in a gas stream that travels through the medium at a speed equal to the velocity of sound, with a velocity independent of the velocity of the flowing fluid. The purpose of this paper is to discuss its effect on flow measurement by orifice, turbine, and positive displacement meters and to discuss what can possibly be done to correct the problem.
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Document ID:
8AF64FC4
Introduction To Orifice Measurement
Author(s): Thomas G. Voisey
Abstract/Introduction:
With the advent of severe gas shortages and the inevitable increase in the price of gas, it becomes more important that much care be given to insure the accuracy of all forms of gas measurement. Orifice measurement, by its very nature, is used to measure large volumes of gas. Strict adherence to specified design tolerances and accepted test and inspection procedures are essential for accurate measurement. The standards for the design, installation, and calculation of flow of orifice meters have been set forth in the publication entitled Orifice Metering of Natural Gas, Gas Measurement Committee Report Number Three, sponsored by the American Gas Association. The facts and figures contained in this report were derived by running many actual tests on orifice meters under various conditions that would be found in the field. Data contained in Report Number Three are the basis for the test and inspections outlined in this paper.
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Document ID:
8F148156
Overall Measurement Accuracy
Author(s): Howard W. Berghegger
Abstract/Introduction:
The subject title is one of many which would have been applicable, such as: Do Your Measurement Books Balance? Does Your Sales Volume Your Purchase Volume? Are You Selling All The Volume Youre Entitled To? Do You Really Have Good Measurement? If you can honestly answer No to the above, then it will be beneficial to explore a few basic reasons for measurement problems. When the word measurement is mentioned, the majority of the gas industry measurement personnel automatically convert their thoughts to meter. The meter contributes only 1/2 to 1/4 toward the total science of measurement depending on the application.
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Document ID:
BF8F30C9
Rotary Meters
Author(s): W. K. Clark
Abstract/Introduction:
The first rotary positive displacement gas meters were built about 1920 by the PH & FM ROOTS Company and the Connersville Blower Company, both located in Connersville, Indiana. The two companies later joined to form ROOTS-Connersville Blower, and in 1966 the gas meter operation was re-named Dresser Measurement Division. The rotary gas meters manufactured by Dresser Measurement are known as ROOTS Meters. Rockwell International entered the market in the early 1960s with a rotating vane design known as the ROTO-SEAL Meter and in the late 1960s, Singers American Meter Company introduced still another rotating vane design known as the CVM gas meter. The operating principles for each of these three meters are depicted and explained in Figures 1, 2, and 3. Since the majority of meters in use today are the ROOTS Meters, the comments in this paper will be directed toward the ROOTS Meter however, most comments are directly applicable to the other types of rotary meters.
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Document ID:
B0C8DD0B
Turbine Meters
Author(s): Charles W. Bolam
Abstract/Introduction:
Turbine meters were introduced to the gas industry in the early 1960s with the Rockwell 6 gas turbine meter. Because of the necessity of a highly accurate measuring device over a relatively large range of pressures and flow rates, the turbine meter has developed into a line of meters capable of measuring low flow rates of 800 scfh and large flows in excess of 1.4 x 10* scfh. The operating pressure of a turbine meter may be less than atmospheric or up to high pressure applications in excess of 1400 psig. The turbine meter is a compact, lightweight, line-mounted measuring device which the gas industry feels is a reliable method of measuring gaseous fluids.
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Document ID:
D65307FA
Shop Testing Rotary And Turbine Meters
Author(s): George W. Reich
Abstract/Introduction:
With the current concern for gas availability in the United States, utility companies as well as regulatory agencies have increased their demands for accurate gas measurement at reasonable costs. Manufacturers have been forced to spend large sums of money providing sophisticated standards to comply with customers requirements. This paper is designed to familiarize the reader with the types of practical proving equipment and techniques available for shop testing of distribution rotary and turbine meters. One must realize that the diversity of options equals the diversity of costs and that each company must weigh carefully the cost of testing versus their probable loss of revenues from measurement error.
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Document ID:
F71F2390
Appalachian Energy Resources Are Vital To The Achievement Of Self-Sufficiency
Author(s): Jennings Randolph
Abstract/Introduction:
Greater utilization of our countrys naturally abundant energy resources can free us from dependence on the vagaries of foreign energ producers. We also need relief from the economic burden of long-term major balance-of-payments deficits. The right of individual choice as American citizens is important. On the eve of the 200th anniversary of the American revolution, the independence to determine the future of America - not just our energy future - is in jeopardy. The challenge is here. The challenge is now. What is needed is acceptance and a solid commitment to meeting our energy needs from domestic sources. Appalachia is blessed with abundant energy resources. As a prime Eastern source of domestic energy supplies, Appalachia can play a special role in achieving energy self-sufficiency. This is especially true for the wealth of coal, which will become increasingly significant in efforts to promote energy independence.
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Document ID:
334AFFA3
Field Testing Rotary And Turbine Meters
Author(s): Paul J. La Nasa
Abstract/Introduction:
The ever-increasing use of gas turbine and rotary meters has created many problems in establishing suitable methods for field testing. The requirement for field testing is predetermined by the need, through contract or otherwise, to maintain and demonstrate accuracy in measurement. In attempting to establish suitable testing methods, efforts are made to obtain laboratory results under field conditions. At best this is a frustrating experience, although necessary. Field test and the laboratory calibrations will only approach each others results. The degree of difference can be attributed to many factors such as environmental conditions, instrumentation, duration of run, variations of flow stream, and difference in standards.
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Document ID:
97FEB0ED
Mechanical Readout Devices
Author(s): Raymond G. Kremer
Abstract/Introduction:
When a utility purchases gas from a pipeline transmission company, it does so at an agreed set of conditions of pressure and temperature. Then, regardless of the actual pressure and temperature at which the gas is delivered, when the utility is billed for this gas, the volume is corrected and related back to the agreed base conditions. The fact that pipeline gas is delivered at relatively high pressures, and since natural gas is a mixture of several gases and thus deviates from the basic laws of physics pertaining to perfect gases, results in still another factor being introduced, called supercompressibility. When the utility sells this gas along with any additional supplies that it may have produced, it is important that the sum total of this send-out can be related to the purchases and other sources. If it does not, the problem of unaccounted for gas rears its ugly head.
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Document ID:
88E19B4C
Electromechanical And Electronic Readout Devices
Author(s): W. m. Hannah
Abstract/Introduction:
A counter is basically a storage or memory device used for accumulating or totalizing a series of events, the events in the gas industry being the number of turns a shaft makes which is equal to a specific volume of gas passing through a meter. The counting device on a meter is called an index by the gas industry and the meter manufacturers. The simplest type of counter is a single dial with numerical values around its circumference and a needle which moves from zero to higher and higher values, as an example, the odometer in a vehicle. The index of a utility meter is an extension of the single dial to several dials, each coupled to the other with 10 to 1 direct gearing. The meter reader carefully reads each scale indication lower in value than each digits pointer indicates. The possibility of making an incorrect reading is very great. Counterrotating dials increase the possibility of error, and this introduces serious problems.
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Document ID:
24868399
Osha & The Meter Shop
Author(s): Donald F. Bulger
Abstract/Introduction:
Safety and health laws are really not new to industry, but until the new Occupational Safety and Health Act (OSHA) was enacted, theyve been on a stateby- state basis. Some states were stricter than others and most not very well enforced. Now, the federal government has set the laws, and safety and health take on a real meaning. You have to know all the ins and outs or face stiff fines and penalties. For many years the gas industry has set strict safety rules and regulations regarding their product and the safety of their workers. Many of these rules were derived from the American National Standards Institute guidelines which have been the basis for OSHA. We have found, however, new things in OSHA that we have had to comply with, and as a whole, these have been done. It is very seldom that I have the displeasure to read a copy of a citation that has been issued to a gas company. The ones that are issued are normally for failure to train or advise employees of the hazards involved in their jobs and have such training documented with signatures of each employee. I will get into the training aspect of the Act a little later.
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Document ID:
2AA1D286
Domestic And High Capacity Positive Displacement Diaphragm Meters
Author(s): D. D. Paul
Abstract/Introduction:
In the early days of the gas industry, gas was used primarily for lighting and for a relatively few number of customers. At that time, many gas companies did without metering by charging the customers a flat rate and by trying to anticipate the amount of gas required to satisfy the customers. As the gas industry expanded, however, this became an inefficient and often costly procedure. Customers charged on a flat rate basis often took advantage of the fact, using the gas as a heat source and also by tampering with the lights in order to get the most for their money. These problems not only contributed to a loss in revenue to the gas companies but also made it very difficult to determine the amount of gas required to sustain an adequate supply. As a result of these problems, it became increasingly important to the gas companies to find some mechanism that would measure precisely and reliably the amount of gas that was delivered to a customer. In order to be an effective billing implement, it had to receive the respect and confidence of the customers and in order to be economically feasible, it had to be inexpensive to purchase and then extremely inexpensive to maintain. These reauirements gave rise to the development of the gas meter industry and specifically to the extensive use of the positive displacement diaphragm meters. Over the years sin,* the early 1900s, positive displacement diaphragm meters have developed into a remarkable combination of economy, reliability, and durability and have, therefore, very satisfactorily answered the needs of the gas industry.
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Document ID:
91CABA66
Field Test And Repair Of Large Capacity Displacement Meters
Author(s): Harry W. Aivalotis
Abstract/Introduction:
The entire concept of meter maintenance is rooted in economics. Both the gas company and the customer look upon the gas meter as a cash register-an arbiter of dollars-because each is concerned that true value be received for money spent. Regulatory agencies have part of their roots bedded deeply in the economics that stem from the publics desire that some basis of law guarantee fair treatment in the market place. More and more our product has become a premium energy source the cost of gas now and in the future, compared to the relatively cheap gas of years gone by, mandates that measurement be as accurate as possible. The forces of both law and economics make mandatory a meter maintenance program for any gas company. Whether or not large volume meters are tested and maintained in the field or in a meter shop is a matter of company policy, organization, and geography. Testing meters on location requires an investment in specially trained personnel, special test equipment and, to be efficient, meter settings equipped with bypass facilities and test connections. It should be possible for the meterman to quickly and easily bypass the meter without interrupting service to the customer, take the meter out of service, and connect the test equipment.
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Document ID:
DC3CA8A0
Temperature Compensated Diaphragm Meters
Author(s): Richard H. Schieber
Abstract/Introduction:
Of the three most common forms of fossil fuels (gas, oil and coal) only gas is elastic in nature and thus must be measured under known temperature and pressure conditions as well as in volumetric units. It is, after all, the heating value or BTU content that is actually being bought and sold and not actual cubic feet when we are dealing with natural gas. And because the BTU content in a volumetric cubic foot is a function of the pressure and temperature of the gas, measurement and/ or control of these variables is important to overall measurement accuracy. Diaphragm type gas meters with internal temperature compensation were first introduced in about 1957. Today the temperature compensating option is one of the most popular features in all types of diaphragm meters, from the domestic to the industrial sizes. This wide acceptance is easily understood when the advantages of temperature compensation are compared to the low initial investment. The following article will explain how temperature compensation is accomplished, its effect on overall measurement accuracy, and how its use is economically justified.
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Document ID:
1B45F137
Fixed Factor Meter Installations
Author(s): David R. Greer
Abstract/Introduction:
A study has been done by the Engineering Department of Columbia Gas Distribution Companies to determine the feasibility of using fixed pressure factor measurement as an alternative to our present method of elevated pressure measurement. Presently, our normal installation contains a meter measuring at line pressure and a monitored set of regulators cutting to the customers delivery pressure. As an alternative, we have considered installing a monitored set of regulators upstream of the meter cutting to the delivery pressure. The meter would then have a pressure compensated index that is read directly or a standard index which is read and sent to accounting where a correction factor is applied by the computer. In order to make the study workable, the scope was restricted to 10 psig measurement with only diaphragm meters as the measuring device. Over a period of seven years, our company has made 28 installations of 10 psig sets on an experimental basis. The regulation in these stations is of a wide range of regulators from rough cut farm tap type regulators to pilot operated regulators.
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Document ID:
F327A154
Analysis Of Shop Test Results
Author(s): Ernest Greenhill
Abstract/Introduction:
The question that arises in the industry is why and how to evaluate the test results of gas meters. Before we can evaluate the results, we must be aware of the variations that can exist during the calibration and in-testing procedures. These fall into three general categories: 1. Temperature controls environment 2. Calibrating equipment and its maintenance 3. Proving technician
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Document ID:
A9029BA0
Impact Of The Metric System On The Gas Industry And The Meter Shop
Author(s): John L. Esola
Abstract/Introduction:
After years of debate in government and industry circles, a changeover to the metric system appears inevitable for the United States. Many corporations have already taken the initiative, rather than wait longer for definitive government action. The United States is the only major industrialized nation that has not yet adopted the metric system. Approximately 93% of the worlds population, living in countries that conduct three-fourths of its trade, use metric units. Therefore, it seems that the real question is not will the metric system be adopted, but rather when will the system be adopted.
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Document ID:
204B82B5
Basic Gas Laws
Author(s): Carl A. Culley
Abstract/Introduction:
This paper is an explanation of the basic gas laws and will illustrate primarily the effect of pressure and temperature on metered gas volumes. These are the laws we refer to as Boyles Law and Charles Law For purposes of measurement, a cubic foot of gas is that quantity of gas which would occupy one cubic foot of space when placed under definite specified conditions. The pressure and temperature at which gas is purchased or sold is a matter of contract and not necessarily the conditions that exist when metered. Contract conditions are therefore referred to as base pressure or base temperature. All gas measured at conditions other than specified in a contract must be mathematically corrected to the volume it would occupy at the base pressure and base temperature. In this geographical location, air exerts a pressure of 14.4 pounds per square inch. To force gas through a pipe, it must be under sufficient pressure to overcome this air pressure.
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Document ID:
169236EF
One Companys Approach To Training The Regulator Man
Author(s): A. Resowski
Abstract/Introduction:
Our pressure control group is responsible for the maintenance and repair of district regulators and allied equipment. They are also responsible for another critical function, the drilling and stopping of distribution mains for tie-in work, etc., by other company personnel or contractors. This dual responsibility makes selection and training of personnel a major concern. At this point I will, however, concentrate on the training programs related to regulation. Training in prior years was principally on the job training provided by a longterm senior employee acting as the crew leader. The training was not structured and, as you can guess, was dependent upon the abilities of both the leader and the helper to communicate with each other. The approach, a kind of rub-off technique, was suitable years ago when we had only two types of regulators in the system and a long period of apprenticeship. Proper on-the-job training is still considered a very important training method however, for the following reasons we expanded our training approach and programs.
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Document ID:
E3840727
Ball Valve Regulators-Description And Use
Author(s): H. J. Becker
Abstract/Introduction:
Years ago one of the plug valve manufacturers equipped a valve with a pneumatic cylinder and a positioner and offered it as a monitor regulator. The concept was definitely a new method of gas regulation and was the beginning of a new era. I dont believe the plug valve manufacturer realized what he had done toward the design of the modern high capacity regulator. A midwestern utility used these plug valve regulators above grade with relatively good success. They believed, however, that a buried valve regulator (Figure 1) would be more desirable than an above ground unit and would greatly reduce the cost of a pressure or flow control station. Units of this nature which were built in the gas utilities shop were successful and proved to be the key to todays modern pressure and flow control stations. Many manufacturers are now building valve regulators utilizing plug valves, sliding disc valves, and ball valves. I believe, however, that any valve can be used to make a regulator.
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Document ID:
562C8C36
Overpressure Protection Relief Valves Or Monitor Regulators
Author(s): Bernard C. Malmfeldt
Abstract/Introduction:
the desire for safe operating conditions and more recently demanded by the regulations of the Department of Transportation (D.O.T.). The D.O.T. regulations Part 192 set forth the performance requirements for proper overpressure protection in sections 192.195, 192.197, 192.199, and 192.201. The general requirements for overpressure pressure protection are stipulated in section 192.195 therefore, a review of this section will provide a better understanding of what we need to accomplish.
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Document ID:
74BA328D
Direct Or Pilot Operated Regulators A Choice To Be Made
Author(s): Kenneth C. Depew
Abstract/Introduction:
The models and types of regulators and regulator control systems which we now use at Public Service are to a large degree the product of our companys past practice, past practice that was determined by the old basic requirements of large low pressure mains supplied by an intermediate pressure system operating from 2 to 7 lbs. per sq. in. Industrial regulators also were large and supplied gas at approximately 5.0 w.c. Until the early 1960s the system was predominantly manufactured gas at 604 BTU/cu. ft. Before I discuss some specific installations and their method of operation, I would like to list and define several terms which are used within Public Service, but which may or may not be understood by others: Fail open regulator-A regulator whose body configuration is such that the spring or other loading mechanism will tend to make the regulator open wide.
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Document ID:
A771E7E5
Regulator Freezing - Occurrence And Prevention
Author(s): Wade O. Hetrick
Abstract/Introduction:
Water in some form is present in all natural gas and is the basic ingredient of the hydrate formations responsible for most regulator freezing. In order to cope effectively with the problem of regulator freezing, it is necessary to understand the nature of the water-gas relationship: the conditions favorable to the formation of hydrates and the basic techniques used to prevent hydrates from forming. When water is present in natural gas in the liquid form, it is called free water. When it is present in a diffused form or gaseous state, it is called water vapor. The amount of water vapor a gas can hold is dependent on the temperature and the pressure. If the pressure remains constant, the ability of the gas to hold water vapor increases as the temperature increases. If the temperature remains constant, the ability of the gas to hold water vapor increases as the pressure decreases. See Figure I.
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Document ID:
C5AD7BBD
Design Of A Telemetering System
Author(s): Fred E. Gross, Rodney G. Fuchs
Abstract/Introduction:
Telemetering in some form or another has been an integral part of data acquisition and control systems in the gas industry for many years now. In an operation as diverse as a gas distribution or transmission system, the information needed to monitor and control these systems can be spread out over many hundreds of miles. There has always been a need to centralize this information in one place. With the increasing use of computers and the need for better and more precise control techniques, accurate data transmission is a must. The intent of this paper is to provide some background into the telemetry systems which have been used over the years and to take a look at what a typical modern digital telemetry system involves.
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Document ID:
3E0DE75C
Electronic Flow Computers - Theory And Application
Author(s): Michael J. Keady
Abstract/Introduction:
Traditionally, orifice meter signals have been recorded on-site by means of mechanical circular chart recorders. These charts have been collected weekly or monthly and integrated for volume determination. This procedure has a lengthy lag between time of actual gas flow and time of reporting. With the advent of spiraling gas prices and penalty clauses for excessive rate deliveries, both customer and supplier are looking toward quicker and more accurate methods of obtaining flow and total quantity. By use of field mounted electronic flow computers, flow information is processed on an instantaneous and continuous basis.
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Document ID:
71948C1C
Installation And Maintenance Of Densitometers
Author(s): D. A. Mcnally
Abstract/Introduction:
There are two basic types of densitometers on the market today. They are the buoyancy and the vibrating or frequency type. The first type to be discussed is the buoyancy or balance densitometer. This particular device utilizes Archimedes principle in much the same manner as the old Acme balance. Archimedes states that a body partially or wholly immersed in a fluid is buoyed vertically upward by a force that is equal in magnitude to the weight of the amount of fluid displaced. This is a well-known principle and wont be discussed in this paper.
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Document ID:
74373419
Comparison Of Calculated And Measured Heating Values Of Natural Gas
Author(s): Donald C. Melrose
Abstract/Introduction:
Analytical data for 879 samples of natural gas were studied to correlate the difference in calorimeter heating value and calculated heating value, with parameters of specific gravity, range of heating value, concentrations of various inert gases, and classification of gases. The differences in instrument and calculated specific gravities were similar in magnitude and algebraic sign to the corresponding differences in heating values. The similarities may be a result of the resolution characteristics of both the higher hydro* carbons and the water that are present in the chromatographic back-flush. The differences of measured and calculated heating values were independent of nitrogen concentrations from 0% to 7% but may be dependent upon concentrations of carbon dioxide that are greater than the Vz% limit of most of the samples in the study.
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Document ID:
8E7C7117
Pneumatic Control Techniques
Author(s): John C. Willis
Abstract/Introduction:
To some people the term automatic control suggests computer automation. To others, automatic control is as simple as the thermostat on babys bottle warmer or the timer on an oven. Modern toasters, washing machines, dish washers, and clothes dryers all use some form of automatic control. Many of these every day examples of automatic control are classified as open loop devices. That is, there is no feedback of information from the process to modify the control cycle. If the clothes in the automatic dryer are not dry, the dryer has not necessarily malfunctioned. What is required is feedback from the housewife in the form of an adjustment of the timing cycle. This closes the control loop and makes what is known as closed loop control. This same control could be accomplished if a device were available to sense the dryness of the clothes and adjust the timing cycle accordingly. Closed loop control is encountered more frequently in industrial process work than it is in the home.
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Document ID:
3D2B0404
Fundamental Principles Of Orifice Metering
Author(s): E. J. Burgin
Abstract/Introduction:
Unlike the positive displacement meter, the orifice meter does not measure volume. Instead it measures physical characteristics of a fluid such as pressure and pressure differential which can be converted into flowing volumes by use of a basic equation developed by a Swiss scientist, Daniel Bernoulli, in 1738. Since volume is obtained with an orifice meter after a determination of the physical characteristics, it can be termed an inferential-type meter that is, measurement is by inference or deduction. Before reviewing Bernoullis theory and the basic hydraulic formula, it is interesting to note that fluid metering began with water measurement and is as old or perhaps older than recorded history. It is known that the ancient Babylonians and Egyptians used some means of measuring or proportioning water from their irrigation systems to individual land holders. It is thought that their methods were adapted from procedures used in Eastern Asia at an earlier period.
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Document ID:
0895789E
Digital Computers For Gas Measuring Systems
Author(s): Robert D. Goodenough
Abstract/Introduction:
As early as 1966, Tennessee Gas Pipeline Company was investigating a telemetering and control system to benefit our gas control facilities at Hockley, Texas. Field hardware suitable for such a system was not available at the time. As suitable components became available, the components were evaluated by company personnel, and in 1971 steps toward actual installation of a data acquisition and control system (DAC) were begun. The primary purpose of the DAC system is to give the dispatcher the latest up-to-date information about pipeline operating conditions. Until this time, dispatchers obtained line pressures at set intervals by telephone and calculated volumes of gas bought and sold during the previous day for dipatching purposes. This meant that the dispatcher was using historical data to operate the pipeline system Now. The first phase of the DAC installation brought volume information from major purchase stations to the dispatcher. The subsequent phases added additional purchase station volumes, selected sales station volumes, flow control at selected meter stations, suction and discharge pressures and temperatures from all compressor stations, engine status at compressor stations, and discharge setpoint control of compressor stations. The original purpose of the DAC system was to supply information to the dispatcher so that the pipeline system could be operated more efficiently, but now, during periods of curtailment, it can be very useful in predicting operations of the pipeline system.
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Document ID:
42152E6D
LNG Transportation
Author(s): William A. Ross
Abstract/Introduction:
LNG transportation is a rather broad category. Recognizing this, the purpose of this paper will be to discuss generally the transportation methods presently in use and quickly review those proposed but not yet in existence. The basic areas to be covered are as follows: 1. Ship and barge transportation of LNG-a rapidly growing area. 2. Pipeline transportation of LNG which to date has only been studied. 3. Rail transportation-another method that holds some promise for the future. 4. Truck transportation which is an important element in todays distribution patterns. In conjunction with truck transportation, some time will be spent on portable vaporizing equipment which with LNG trucking offers a valuable maintenance tool to the pipeline and distribution areas of our industry.
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Document ID:
EFCF9CA0
Sng Gas Measurement
Author(s): Kenneth J. Fulk
Abstract/Introduction:
Substitute natural gas (SNG) manufacture is a new industry in the United States. The first gas produced was in early 1973. Today there are several plants producing substitute gas with others under construction or in the process of being started. Like some of the other plants the Columbia LNG Corporation uses the proprietary British Gas Council catalytic rich gas (CRG) process for hydrocarbon gasification. It is a process that uses a special nickel oxide catalyst that in the presence of steam converts hydrocarbon feedstocks into methane, the primary constituent of natural gas. The produced gas has a final heating value over 1000 BTU/SCF and is interchangeable with pipeline natural gas. As far as measurement of the gas is concerned, it can be measured using standard gas measurement equipment. The only real difference between the two is that the minor or trace components of each are different and must be accounted for in their measurement. As shown in Table 1 natural gas historically has contained minor amounts of ethane, propane, and other compounds. The minor compounds in substitute natural gas are primarily hydrogen and carbon dioxide.
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Document ID:
A12159EC
Plant Description And Selected Instrument Applications
Author(s): W. E. Boldyreff
Abstract/Introduction:
Consumers Power Company is a privately owned gas and electric utility with a gas service area of 12,775 square miles in Michigans Lower Peninsula. Consumers provides its 950,000 gas customers with an average yearly consumption of 330 billion cubic feet. Peak day consumption is around 2.3 billion cubic feet. Michigan, like most other states, has been affected by the shortage of natural gas. Consumers Power anticipated this situation and took several important steps, one of which was to construct the nations first large synthetic natural gas (SNG) plant at Marysville, Michigan. At full operation, the plant converts about 50,000 barrels per day (BPD) of liquid hydrocarbons into 220 million cubic feet of synthetic natural gas (SNG) providing about 20% of the Consumers supply.
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Document ID:
20AF7EF1
Field Testing For Hydrogen Sulfide In The Gas Stream
Author(s): Howard N. Lewis
Abstract/Introduction:
I. Scope: Hydrogen Sulfide, H2S, in the natural gas stream is undesirable, as it is extremely corrosive to metal equipment with which it comes in contact. It has a deterious effect on catalysts in certain chemical processes and has a very offensive odor. There is a much greater toxic effect on people than with carbon monoxide, and the threshold limit value by American Conference of Governmental Industrial Hygienists (1972) is 10 PPM (7-8 hours). II. Methods of Field Testing A. Pump and detector tube method B. Lead acetate method C. Tutweiler method III. Pump and Detection Tube Method A. Basic apparatus 1. Included in the Unico No. 400 Gas Detector Kit are the pump, metal carrying case, spare parts, and operating manual.
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Document ID:
570C8ECD
Energy Measurement
Author(s): Mendal L. Yoho
Abstract/Introduction:
It seems appropriate that this presentation should be prefaced by an acknowledgment. The conceptual solutions for an energy measurement program for Consolidated Gas Supply Corporation were developed under the direction of Kenneth C. Yost. The ideas presented here are the results of his efforts toward better measurement techniques for the gas industry. INTRODUCTION Three major ideas are presented here: 1. Energy measurement is necessary. 2. Energy deliveries can be calculated using specific gravity and mass flow measurements. 3. Densitometers, gravitometers, and electronic calculators can provide onsite energy measurement.
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Document ID:
6B0E6401
Theory And Operation Of Pilot Controls
Author(s): R. H. Welker
Abstract/Introduction:
It is important for gas men who work with pneumatic controllers on a day to day basis to really understand them. Not to understand the controller under these circumstances can be a continual burden to the operator in addition to presenting circumstances for an operation of lower quality than generally desired. Therefore, the objective of this paper is to try to help develop an understanding and attitude toward a device that is absolutely essential to gas control. When we speak of controllers, we want to differentiate them from the Pilot type of control. In general terms a pressure controller is a separate unit from the control valve, and it has constant bleed to atmosphere. Again in general terms we think of pilot controls as being an integral part of the control valve and that has a downstream bleed. What is the difference in these two types of controls? One important difference is the fact that the pilot system can never match the efficiency of a pneumatic controller because it is the controller which contains reset, the function that keeps our process on set point regardless of changes in upstream pressure or load.
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Document ID:
2472358A
Fundamentals Of Gas Pressure Regulation
Author(s): Floyd D. Jury
Abstract/Introduction:
Gas pressure regulators have become very familiar items over the years, and nearly everyone has grown accustomed to seeing them in factories, public buildings, by the roadside, and even in their own homes. As is frequently the case with many such familiar items, we all have a tendency to take them for granted. Even the gas man who handles regulators every day as part of his job frequently tends to view the regulator simply as a piece of hardware which fits in the line and regulates pressure. The fact that it will do precisely that, for months on end without human intervention, makes it easy to maintain such a view. Its only when a problem develops or when we are selecting a regulator for a new application, that we need to look more deeply into the fundamentals of the regulators operation.
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Document ID:
4E298F7B
Fundamentals Of Turbine And Rotary Meters
Author(s): J. J. Fitzpatrick
Abstract/Introduction:
Gas measurement becomes more important as the requirement for gas as an energy source continues to grow. It is becoming increasingly important to measure gas at the most economical cost, maintaining safe operating practices, and attaining accuracy levels which are equitable to all concerned. In discussing fundamentals of measurement, we will review the operating principle, performance characteristics, sizing, and application of rotary and turbine type meters. Both of these types of meters have been developed to provide the gas industry with a highly accurate line of meters which are lightweight and compact in size requiring a minimum of space at the metering site.
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Document ID:
3704B40B
Pressure Fundamentals And Transmitter Selection
Author(s): D. Bulen
Abstract/Introduction:
This paper presents the definition of pressure and fundamentals of pressure measurement, as they relate to industry, and factors that should be considered in selecting a pressure transmitter. Included are definitions of functional specifications, performance specifications, and material selection, and their relationships to functional and performance requirements.
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Document ID:
9E540FEC
The Vortex Shedding Insertion Flowmeter Its Uses In The Gas Industry
Author(s): Kenneth L. Guenther
Abstract/Introduction:
The cost of large full line size meters is initially high and rises significantly in relation to increasing size. In cases where flow control or other operations where repeatability is the prime factor desired in a measurement, an insertion type flowmeter can present a viable alternative. The insertion device further described in this paper measures velocity based on vortex shedding. Vortex shedding is the name given to the natural effect that can occur when a gas or a liquid flows around a blunt or non-streamlined object. A fixed bluff object of a particular shape is placed inside a circular shroud and that assembly is inserted into the duct where velocity is to be measured. If the inserted assembly has the correct relative dimensions, vortex shedding from the fixed, bluff object (flow element) will occur in a steady, regular fashion, at a frequency proportional to the fluid velocity. It is important to note that vortex shedding occurs by virtue of the flow itself - no moving mechanical parts are involved. The resulting flow pattern, which is shown in schematic form in Figure 1, results in an oscillatory motion of the flowing fluid, at the frequency of vortex shedding.
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Document ID:
213DE45E