As is well known, fluids often need to flow through various valves during transportation Elbow. tee. When fluid passes through flow barriers such as reducers, various disturbances will be generated. If a flowmeter is installed at this time, it will bring certain additional errors to the on-site installation of the flowmeter, especially for traditional differential pressure flowmeters. The balanced flow sensor cleverly integrates rectification and measurement, which has the function of stabilizing the flow field, reducing additional errors, and making the actual use accuracy close to the theoretical calculation accuracy. It is a new generation differential pressure flowmeter with broad application prospects, which will be used in natural gas Chemical industry Oil Steel electricity generation. papermaking. Printing and dyeing Her figure is showcased in fluid measurement for pipeline transportation in various industries such as pharmaceuticals.1. Measurement accuracy: As the porous balanced flow sensor is actually a flow rectifier, it can effectively eliminate vortices and improve velocity distribution distortion, making the flow field approximate an ideal state. The conventional measurement is at level 0.5, and the accuracy measurement is at level 0.2.
2. Range ratio: Due to the difficulty of measuring large caliber and small flow rate in most flow sensors, porous balance flow sensors have a porous structure. Choosing an appropriate equivalent diameter ratio can focus on measuring the lower limit flow rate while also considering the upper limit flow rate, resulting in a conventional measurement range ratio of 10:1. If the parameters are selected appropriately, it can be increased to a range of 30:1-50:1
3. The requirements for straight pipe sections are low, and a certain length of straight pipe section is mainly used to make the fluid flow smoothly in it. The porous balanced flow sensor itself is a flow regulator, so it can be almost directly connected to the valve tee. Elbows and other flow blocking components do not affect normal measurements.
4. Low permanent pressure loss. Installing a flow sensor in the pipeline inevitably results in pressure loss due to its flow blocking effect. The porous structure in the porous balance flow sensor can disperse the resistance, effectively reducing the formation of eddies and turbulent friction, thereby reducing permanent pressure loss.
5. Main technical parameters and indicators
Caliber: from DN3-DN3000
Accuracy level: ± 0.2% ± 0.5% ± 1.0%
Repeatability: 0.1% 0.2%
Range ratio: 10:1 (or higher)
Medium operating temperature: ＜ 600℃
1. Working principle of porous balanced flow sensor
If a flow blocking device (commonly known as a throttling device) with a flow area smaller than the cross-sectional area of the pipeline is fixedly placed in a pipeline filled with fluid, the fluid in the pipeline will locally contract when passing through the throttling device. At the contraction point, the flow area will decrease, the flow velocity will increase, and the static pressure will decrease. Therefore, a certain differential pressure will be generated before and after the throttling device. The balance flow sensor also works based on this principle. It can not only generate differential pressure, but also because the throttling device in the balance flow sensor is also a rectifier, the differential pressure generated is particularly stable. According to the laws of mass conservation and energy conservation in fluid mechanics, the volume flow rate and mass flow rate of the fluid can be calculated.
2. Fluid that can be successfully measured by a balanced flow sensor
gas
a、 Gas: Coke oven gas, blast furnace gas, city gas, semi water gas.
B、 Natural gas: Large caliber, low pressure, low flow rate, including natural gas with a moisture content of over 5%.
C、 Various hydrocarbon gases: alkanes, alkenes, and other gases.
d、 Various gases produced by gas pressure stations: oxygen CO2、 Argon, nitrogen, acetylene, etc.
e、 Corrosive gases: wet chlorine gas, wet chloride gas, etc.
f、 Gas produced in the air conditioning room: compressed air, including air containing water, dust, and oil droplets.
h、 Boiler room flue gas: blower air volume, induced draft fan air volume, flue gas.
steam
a、 Saturated steam
b、 superheated steam
liquid
a、 Oil: crude oil, fuel oil, heavy oil, hydrated emulsified oil, diesel, kerosene, etc.
b、 Water: raw water, drinking water, tap water, industrial production water, etc.
C、 Organic solvents: alcohol, methanol, ethylene glycol, xylene, etc.
Special fluid
Oil+HC gas+sand, water with bubbles, H2O+N2+air, H2O+CO2, etc.
Installation and use of flow sensors
One Operation steps for measuring steam flow rate
1. Installation
1. Choose the appropriate installation pipe section, and the V-cone and porous balanced flow sensors do not have high requirements for the length of the upstream and downstream straight pipes.
2. Pay attention to the flow direction and ensure that it is consistent with the arrow (V-cone has this requirement, balanced type can measure dual flow)
3. It is recommended that the direction of the pressure inlet be in the middle horizontal position
4. It is best to blow clean the upstream pipe section before installation to prevent welding slag Foreign objects enter the instrument.
5. The size of the split type pressure pipe can be selected from 14 * 3.5-18 * 4.5, and suitable thick walled steel pipes should be used for high pressure.
If the horizontal installation position is not sufficient, it can also be oriented upwards at a 45 degree angle.
2. Run
1. First, close the shut-off valve and the three valve group. Wait for the high temperature steam temperature to drop below 80 ℃ in the condenser or fill it with cold water in advance, and then put the instrument into operation according to the following steps.
2. First open the middle balance valve, then simultaneously open the left and right shut-off valves, and then simultaneously open the left and right high and low pressure valves.
3. Observe the zero point of the differential pressure transmitter. If there is any deviation, the zero position can be adjusted on site without affecting the range.
4. Finally, close the intermediate balance valve and the instrument will operate normally.
II Operation steps for measuring gas flow rate
1. Installation
1. Choose the appropriate installation pipe section, and the V-cone and porous balanced flow sensors do not have high requirements for the length of the upstream and downstream straight pipes.
2. Pay attention to the flow direction and ensure that it is consistent with the arrow (V-cone has this requirement, balanced type can measure dual flow)
3. The pressure inlet is vertically facing upwards, meaning that the three valve group and differential pressure transmitter are located above the pipeline, and can also be tilted upwards at a 45 degree angle.
4. It is best to blow clean the upstream pipe section before installation to prevent welding slag Foreign objects enter the instrument.
5. The size of the split type pressure pipe can be selected from 14 * 3.5-18 * 4.5, and suitable thick walled steel pipes should be used for high pressure.
2. Run
1. First open the middle balance valve, then simultaneously open the left and right high and low pressure valves,
2. Observing the zero point of the differential pressure transmitter, if there is any deviation, the zero position can be adjusted on site without affecting the range.
3. . Finally, close the intermediate balance valve and the instrument will operate normally.
4. If measuring high-temperature gases, please install a condenser. If measuring dust gases, please install a settling device or use a flange pressure gauge with a remote differential pressure transmitter. If measuring wet chlorine or hydrogen sulfide gases, please use a sensor lined with F46 and install an isolator.
III Operation steps for measuring liquid flow rate
1. Installation
1. Choose the appropriate installation pipe section, and the V-cone and porous balanced flow sensors do not have high requirements for the length of the upstream and downstream straight pipes.
2. Pay attention to the flow direction and ensure that it is consistent with the arrow (V-cone has this requirement, balanced type can measure dual flow)
3. It is recommended that the pressure inlet face downwards vertically, that is, the three valve group and differential pressure transmitter are located below the pipeline. If the installation position is not sufficient, it can also deviate from the horizontal direction downwards, but due to the heavy effect of the differential pressure transmitter, it may need to be supported by a support.
4. It is best to blow clean the upstream pipe section before installation to prevent welding slag Foreign objects enter the instrument.
5. The size of the split type pressure pipe can be selected from 14 * 3.5-18 * 4.5, and suitable thick walled steel pipes should be used for high pressure.
2. Run
1. First, close the shut-off valve and the three valve group. When the temperature of the high-temperature medium in the condenser drops below 80 ℃, press the commissioning instrument
2. First open the middle balance valve, then simultaneously open the left and right shut-off valves, and then simultaneously open the left and right high and low pressure valves.
3. Observe the zero point of the differential pressure transmitter. If there is any deviation, the zero position can be adjusted on site without affecting the range.
4. Finally, close the intermediate balance valve and the instrument will operate normally. When dealing with wet chlorine or hydrogen sulfide gas, please use sensors lined with F46 and install isolators

TMF balance flowmeter