In modern automated systems for monitoring and accounting of energy resources and water, the main devices collecting data from consumers are water, electricity and gas meters. In order to develop a meter that surpasses the existing ones in its characteristics and ensure the competitiveness of systems using such meters, it is necessary to review the measuring devices available on the market. This paper collects data on natural gas meters.
Gas meter (gas meter) is a metering device designed to measure the amount (volume), less often – the mass of gas passed through the pipeline. The amount of gas is usually measured in cubic meters (m3), rarely in units of mass (this mainly concerns process gases).
Devices that allow measuring or calculating the passing amount of gas per unit of time (gas flow) are called flow meters or flow meters. Most often, gas consumption is measured in cubic meters per hour (m3/h).
Gas meters with slightly worse accuracy than conventional commercial meters, designed only for technological or on-farm accounting, are often called quantometers.
Gas meters differ in design, in their characteristics and functional purpose.
Main characteristics of counters:
Throughput is the range of expenses in which the meter measurement error declared by the manufacturer is provided.
According to the maximum throughput, gas meters are conditionally divided into household, municipal and industrial.
Household
With a maximum throughput from 1 to 6 m3/h. Most often used in apartments, houses, offices, small furnace rooms for local accounting of gas consumption. These are, as a rule, small membrane (chamber, diaphragm), less often ultrasonic, jet, small rotary gas meters.
Public utilities
With a maximum throughput from 10 to 40 m3/h. They are used to account for gas consumption by small boiler houses, technological installations, etc. These are, as a rule, larger membrane (chamber, diaphragm), rotary, ultrasonic, jet gas meters.
Industrial
With a maximum throughput of over 40 m3/h. They are mainly used at metering units of large consumers – gas boiler houses, industrial and agricultural enterprises, metering units of gas distribution networks (rotary, turbine, vortex, ultrasonic, jet gas meters), on main networks (narrowing devices, turbine, vortex, ultrasonic gas meters).
Types of household gas meters by design [1]:
- diaphragm counters;
- rotary counters;
- turbine meters.
Diaphragm meter (membrane, chamber) is a gas meter, the principle of operation of which is based on the fact that with the help of various movable converter elements, the gas is divided into fractions of volume, and then their cyclic summation is performed.
Advantages of diaphragm meters: ease of manufacture, low cost of diaphragm meters, relatively accurate counting even with a small use of gas.
Disadvantages of diaphragm counters: counters practically do not tolerate overloads (both temporary and permanent).
A rotary meter is a chamber gas meter in which eight – shaped rotors are used as a converter element.
Advantages of rotary meters: the rotary meter has a relatively large throughput with a relatively small size and weight, it is durable and can withstand some overloads.
Disadvantages of rotary meters: a rotary gas meter costs more than others because of the expensive materials used for its production, and it also requires careful adjustment of all parts.
Turbine gas meters are gas meters in which, under the influence of a gas flow, the turbine wheel is rotated, the number of revolutions of which is directly proportional to the flowing volume of gas. Recently, the counting mechanisms of turbine gas meters are equipped with modems, thanks to which all readings are directly transmitted to the servers of the checking services.
At gas industry facilities, gas consumption and its quantity are measured mainly by the method of variable pressure drop on the constricting device, using tachometric flow meters and meters, as well as ultrasonic flow meters have been actively introduced recently [2]. Also, various electronic solutions are being introduced into modern natural gas flow meters to improve the accuracy of measurement and the service life of the meter [3].
The essence of the variable pressure drop method is to measure the pressure drop before and after the constricting device installed in the gas flow.
The principle of operation of tachometric flowmeters is based on the dependence of the rotation speed of the converter installed in the pipeline on the flow rate of the substance. The advantages of such devices are high speed, high accuracy, and a large measurement range. The error of the counters is ± 0.5 – 1.5%, the use of tachometric converters can reduce the error of converting the flow rate into the frequency of rotation of the converter to ± 0.3%.
The main disadvantage of tachometric flowmeters is the wear of supports, the presence of movable elements and the main disadvantage, in relation to flowmeters with constricting devices, is the need for calibration installations.
The ultrasonic flow measurement method is based on the phenomenon of displacement of sound vibrations by a moving medium [4,5].
The method is characterized by the following negative factors [6]:
- dependence of the intrinsic velocity of ultrasonic vibrations on the physico-chemical properties of the measured medium;
- the flow velocity is averaged along the ultrasonic beam, and not along the cross section of the pipe.
The latter factor forces developers to supply the design with additional sensors or reflectors, which makes the flow meter more complex, increases the likelihood of operating errors when the sensors of the system fail. Nevertheless, this method has a number of advantages:
1. no pressure drop,
2. high performance;
3. absence of moving elements.
In [7] it is reported that so far the optimal way to measure the flow and quantity of gas in the gas industry is the method of variable pressure drop. The errors of differential pressure sensors, absolute pressure and temperature, as well as calculators are in the range from 0.01 to 0.075% and meet regulatory documents.
The principle of operation of vortex flowmeters (meters) is based on the transformation of the translational motion of the measured medium into a Pocket vortex path by means of a flow body installed across the flow measurements of the frequency of vortex disruption [8]. The frequency of the formation of vortices in the first approximation is proportional to the flow velocity, and their number over a period of time is proportional to the total energy consumption.
The advantage of vortex flowmeters is the absence of any movable elements inside the pipeline, sufficiently good accuracy and linearity in a wide range of measurements, frequency output signal, as well as versatility: the same device after calibration can be a meter of both liquid, gas, and steam [8-10].
It should also be noted that gas meters during operation have variability due to the temperature of the external environment, because the temperature of the gas coming from outside can differ significantly from the temperature in the room in which the meter is located. To account for seasonal temperature changes in the commercial accounting of gas consumption, a special temperature coefficient is used, and the meters themselves use a temperature compensation mechanism. The coefficients are set by the Federal Agency for Technical Regulation and Metrology once every six months, and are valid only for metering devices without temperature compensation installed outdoors.
The analysis shows that the market of household gas meters in the price range has two niches: 2600-4500 rubles and 6000 rubles and above. Moreover, this separation is not due to accuracy characteristics, but to service functions. That is, we can conclude that the consumer is more likely to agree to pay for the convenience of operation, and not for real savings.
Библиографическая ссылка
Polovinchenko M.I., Dubrovina A.I. OVERVIEW OF TYPES AND PARAMETERS OF GAS FLOW METERS USED IN AUTOMATED ENERGY ACCOUNTING SYSTEMS // Материалы МСНК "Студенческий научный форум 2024". – 2022. – № 13. – С. 66-68;URL: https://publish2020.scienceforum.ru/ru/article/view?id=699 (дата обращения: 01.05.2024).