Natural Gas Measurement Using Temperature-Dependent Thermal Conductivity
■Introduction
●Trends in the natural gas market
▲At present the demand for natural gas is growing globally, and the number of power plants and gas engines that use natural gas as fuel is increasing. However, the composition of natural gas varies greatly depending on the place of production, because it is a mixture composed of methane (mainly), hydrocarbons such as ethane, propane, and butane, and noncombustible components such as nitrogen and carbon dioxide. In addition, as in the example of boil-off gas mixed with LNG, it is not rare that the properties of natural gas change when it is used. Therefore, to improve the efficiency of combustion equipment and engines, it is necessary to understand various indicators (calorific value, Wobbe index, methane number etc.), which change depending on the gas composition, in real time.
●Problems in natural gas measurement
▲Conventional calorimeters that utilize heat conduction and gas density meters that calculate oscillation frequency and are used as calorimeters cannot precisely measure a mixed gas containing noncombustible components such as nitrogen and carbon dioxide, because these components will cause error. Changes in ambient temperature and pressure are also error factors and affect device performance.
▲Many gas companies use gas chromatographs, which can measure a mixed gas containing noncombustible components with high precision, but analysis takes several minutes, and thus these instruments cannot be used for real-time monitoring. In addition, the measurement process of gas chromatographs requires a carrier gas (helium), and gas chromatographs are costly. For these reasons, the use of these instruments is not widespread.
▲In recent years, products that utilize the correlation between a combination of physical properties (thermal conductivity, density, etc.) and calorific value are also appearing on the market, but these products require multiple sensors and are relatively expensive, preventing them from becoming popular.
●Features of the calorimeter
▲The calorimeter is a field device for measuring various parameters of natural gas, such as its calorific value, with a high-speed two-second output response.
▲Focusing on the differences in temperature characteristics of thermal conductivity for each component of natural gas, we developed a new measurement method. We change the temperature of the sensing element of a MEMS thermal sensor quickly to five different levels, and using the sensor signals at these temperatures, the calorimeter outputs values such as the calorific value or the methane number, which are calculated based on the correlation method.
▲To process the sensor signal, the calorimeter uses a characteristic equation that incorporates a support vector regression method devised by Azbil Corporation.
▲By adopting the new method based on the thermal conductivity at different temperatures, it is now possible to measure mixed gas containing noncombustible components with high accuracy. In addition, because only a single sensor is used, the electrical circuit and operation processing are simpler, allowing the cost to be reduced.
|
|
|
|
Supplier and Product Introduction |
|
|
|
|
Please see the document for details |
|
|
|
|
|
|
|
|
|
|
|
English Chinese Chinese and English Japanese |
|
|
2018/9/14 |
|
|
|
|
|
|
|
|
1.9 MB |
- +1 Like
- Add to Favorites
Recommend
All reproduced articles on this site are for the purpose of conveying more information and clearly indicate the source. If media or individuals who do not want to be reproduced can contact us, which will be deleted.
Integrated Circuits
Discrete Components
Connectors & Structural Components
Assembly UnitModules & Accessories
Power Supplies & Power Modules
Electronic Materials
Instrumentation & Test Kit
Electrical Tools & Materials
Mechatronics
Processing & Customization
