Turbine flow meter for natural gas

What is natural gas?

Natural gas is mainly composed of methane (85%) and a small amount of ethane (9%), propane (3%), nitrogen (2%) and butane (1%). The specific gravity is about 0.65, which is lighter than air and, it is colorless, odorless and non-toxic gas.
Natural gas is a gaseous fossil fuel mainly composed of methane. It is also used to make chemicals raw materials such as acetaldehyde, acetylene, ammonia, carbon black, ethanol, formaldehyde, hydrocarbon fuels, hydrogenated oil, methanol, nitric acid, synthesis gas, and vinyl chloride.
Natural gas as a gas fuel is one of the earliest and widely used alternative fuels. It is divided into compressed natural gas (CNG) and liquefied natural gas (LNG). Natural gas is one of the safer fuels. It does not contain carbon monoxide and is lighter than air. Once it leaks, it will immediately diffuse upwards and is not easy to accumulate to form explosive gases. It is relatively safer than other combustibles. Many volume and mass flow meters can be used for natural gas flow measurement, such as gas turbine flow meters, vortex flow meters, Coriolis mass flow meters, thermal mass flow meters, differential pressure flow meters, etc.;
The use of natural gas as an energy source can reduce the consumption of coal and oil, thereby greatly improving environmental pollution; natural gas as a clean energy source can reduce sulfur dioxide and dust emissions by nearly 100%, and reduce carbon dioxide emissions by 60% and nitrogen oxide emissions 50%, and help to reduce the formation of acid rain, slow down the global greenhouse effect, and fundamentally improve the environmental quality.

Natural gas applications need natural gas flow measurement

Industrial production and natural gas
Use natural gas instead of coal for factory heating, production boilers and gas turbine boilers in thermal power plants. Natural gas power generation is an effective way to alleviate energy shortages, reduce the proportion of coal-fired power generation, and reduce environmental pollution. From the perspective of economic benefits, natural gas power generation requires less investment per unit installed capacity, short construction period, lower on-grid power prices, and strong Competitiveness. The large-scale use of natural gas energy in the factory must inevitably require the flow measurement of natural gas, so that the factory can be aware of the use of natural gas by using natural gas flow meter to control the energy management of the factory;
Natural gas is the best raw material for manufacturing nitrogen fertilizers, and it is low investment, low cost, and low pollution. The proportion of natural gas in the raw materials for nitrogen fertilizer production is about 80% on average in the world.
With the advancement of natural gas liquefaction and storage and transportation technologies, the global LNG trade has grown rapidly in recent years, and natural gas has increasingly become a global trade commodity. Natural gas custody transfer must accurately measure the flow rate of natural gas, and the demand for various high-precision LNG flow meters has been increasing.

Gas turbine flowmeter for natural gas

The application of gas turbine flowmeter to measure natural gas is more and more extensive, and the gas turbine flowmeter belongs to the velocity type flowmeter. The impeller flowmeter uses the proportional relationship between the rotational angular velocity of the impeller placed in the fluid and the fluid flow rate. It reflects the volume flow of the natural gas through the pipeline by measuring the speed of the impeller. It is a relatively mature high-accuracy gas flow meter .
The natural gas turbine flowmeter is composed of a turbine flow sensor and a flow display instrument (natural gas flow totalizer), which can realize the measurement of the instantaneous flow and cumulative flow of natural gas. The sensor outputs a pulse/ frequency /4-20mA signal proportional to the flow of natural gas to realize remote display or process control purpose.

Natural gas turbine flowmeter is generally composed of the following parts:

• 1. Flow meter body
• The material of the flow meter body is generally cast iron or stainless steel, and its two ends are connected by flanges or thread process connections
• 2. Rectifier
• The rectifier is used to make the natural gas flow through the turbine flowmeter in a regular state to eliminate the adverse effect of disturbance on the metering. Improve natural gas flow measurement accuracy.
• 3. Measuring components
• There are precision-machined blades on the turbine, which together with a set of gears and bearings constitute a measuring assembly inside the flow sensor measuring tube. It can be self-lubricating or external lubricating oil pump to lubricate the bearings
• 4. Magnetic coupling
• Magnetic coupling separates the part of the transmitter from the natural gas in the closed pipeline, and transmits the rotation of the measuring component to the gas flow meter counter.
• 5. Natural gas flowmeter nameplate

The following important information is marked on the nameplate:

• (1) Natural gas maximum working pressure/temperature;
• (2) Minimum and maximum flow range/flowmeter accuracy
• (3) Factory No./natural gas flow meter model
• (4) Explosion-proof, Hazadous area ,ExdIIBT6
• (5) Flowmeter coefficient, wiring information;
• 6. Turbine natural gas electronic display
• The electronic turbine meter head can display the natural gas volume flow meter (m3/h) and total volume (m3);For the temperature and pressure compensated turbine flowmeter, the electronic display can show natural gas working temperature and pressure of ,natural gas flow rate, flow velocity ,standard flow rate Nm3/h And total natural gas (Nm3).it is Turbine digital flow meter.

Advantages of natural gas gas turbine flowmeter:

• (1) High accuracy. The accuracy of the natural gas turbine flowmeter is 1%R~1.5%R. Within the linear flow range, even if the natural gas flow rate changes, it will not reduce the accuracy of natural gas flow measurement.
• (2) Wide measuring range. Natural gas turbine flowmeters turn down ratio is usually 6:1~10:1, and some flowmeters can reach 40:1, so it is suitable for occasions where natural gas flow changes greatly.
• (3) Good repeatability. The short-term repeatability of the natural gas turbine flowmeter can reach 0.05%~0.2%.
• (4) Low pressure loss. Turbine flow meter pressure loss at the maximum flow rate is (0.01~0.1) MPa;
• (5) High pressure natural gas flow meter. Simple flow meter constructions can be made into high pressure gas turbine flow meter
• (6) Digital signal output. The output of the Turbine digital flow meter is a pulse frequency signal (ie a digital signal) proportional to the flow of natural gas, so its accuracy will not be reduced through the transmission line, and it is easy to display natural gas accumulation, which is convenient for long-distance transmission and computer data processing, without zero drift, and Strong interference ability.
• (7) Convenient installation and maintenance. Simple and light flow meter for convenient install, use and maintain.
• (8) Corrosion resistance. The gas flow sensor is made of anti-corrosion materials with good corrosion resistance. It can resist the trace amount of corrosive gas components in natural gas.

Technical Parameters of Natural Gas Turbine Flowmeter

• Natural Gas  flow sensor size: 3/4”,1”,1.5”,2 inch, 3 inch,4 inch, 6 inch, 8 inch,10 inch,12 inch gas turbine flowmeter;
• Natural gas flow measurement range: 2.5-6500 m3/h
• Natural gas turbine flowmeter accuracy: 1%R~1.5%R, repeatability: 0.05%~0.2%
• Gas electronic display head can be rotated 180° for easy observing flow information;
• Natural gas pressure rating standard is 1.6Mpa, which can produce high-pressure natural gas turbines flow meters, such as 40bar, PN64, ANSI 300LB, ANSI 600LB, etc.;
• Power consumption of gas turbine flowmeter: <1w
• Turbine digital flow meter outputs pulse signals, frequency signals and 4-20mA control signals;
• It can realize MODBUS, RS485 or hart communication; 485 communication can be connected with the host computer, and the remote transmission displays natural gas temperature, pressure and temperature standard volume flow after pressure compensation (the value is the volume flow of natural gas at 20 degrees Celsius and atmospheric pressure) And totalized natural gas flow;
• The electronic gas flow meter has a storage function, which can record daily natural gas flow, temperature and pressure information, power-off and restart info, etc.;
• Power supply: 3.6V lithium battery, 24V DC options;