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Integrated temperature and pressure compensation vortex street
overview
Product details
overview
Vortex flowmeter (also known as vortex flowmeter) is an extremely versatile flow measurement instrument that can be used for flow measurement, measurement, and control of almost all gases, liquids, and vapors.
Stress type vortex flowmeter is a type of velocity flowmeter, which is based on the Karman vortex theory and uses piezoelectric crystals to detect the vortex frequency generated when the fluid passes through the triangular column in the pipeline, thereby measuring the flow rate of the fluid. Vortex flowmeters are widely used in industries such as petroleum, chemical, light industry, and power heating.
| The vortex flowmeter has the following characteristics: High measurement accuracy and wide range; Widely applicable media, capable of measuring liquids, gases, and vapors; The working temperature is high, and the medium temperature can reach 350 ℃; No moving parts, no wear and tear, high reliability; The body is made of stainless steel material, which is beautiful and corrosion-resistant. |
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measuring principle
When the fluid medium in the pipeline passes through the vortex generator (triangular column), a vortex phenomenon is generated due to local velocity acceleration (as shown in Figure 1). This vortex splits into two alternating columns, which are called Karman vortex streets.
The release frequency of the Karman vortex street is related to the width of the triangular prism and the flow velocity of the fluid, and is independent of the temperature, pressure, and other characteristic parameters of the medium. It can be expressed as follows:
F=StV/d (Formula 1)
In the formula: f-Karman vortex street release frequency St Strouhal number V medium flow velocity d triangular column width
Strouhal number is an important parameter of vortex flowmeter, which is only related to the Reynolds number Re of the medium. As long as the Reynolds number of the medium inside the pipeline remains within the range of 2 × 104 to 7 × 106, the Strouhal number St remains constant. This allows for the detection of fluid velocity by measuring vortex frequency, and the calculation of the working volume flow rate of the fluid based on the velocity. Combined with the density of the medium, the mass flow rate of the medium can be accurately calculated.
The basic formula for mass flow rate of vortex flowmeter:
Qg=3600f ρ/K (Formula 2)
In the formula: Qg - mass flow rate f - pulse frequency (Hz) ρ - density (kg/m3) K - instrument coefficient (number of pulses/m3)
Technical Parameter
Nominal diameter:
Flange type: DN15-DN300
Insertion type: DN200-DN2000
Scope of application:
Gases: Compressed air, carbon dioxide, oxygen, nitrogen, etc
Liquids: desalinated water, softened water, high-temperature water, etc
Steam: saturated steam, superheated steam
Medium temperature:
Low temperature: - 40℃-150℃
Medium temperature: - 40℃-250℃
High temperature: - 40℃-350℃
Nominal pressure:
Low voltage: ≤ 1.6MPa, ≤ 2.5MPa
Medium voltage: ≤ 4MPa, ≤ 6.3MPa
High voltage: ≤ 10MPa, ≤ 16MPa, ≤ 25MPa, ≤ 42MPa
Accuracy level:
Measuring liquid: 1.0 grade (0.5 grade can be ordered by agreement)
Measurement gas: Level 1.5 (Level 1 can be ordered by agreement)
Measurement of steam: Level 1.5 (Level 1 can be ordered by agreement)
Insertion type: Level 2.5
Flow rate range:
Liquid: 0.35-8m/s
Gas: 3-70m/s
Steam: 2.5-75m/s
Measurement range: see Table 1, Table 2, Table 3
Output signal:
Voltage pulse: Low level ≤ 1V, high level ≥ 6V
Standard current: 4-20mA
Power supply:
Voltage pulse output: DC12V/DC24V
4-20mA standard current output: DC24V/DC24V+3.6V lithium battery
Integrated header display: 3.6V lithium battery
Environmental temperature: - 20℃-+55℃
Relative humidity: 5% -90%
Table body material: 304 stainless steel, other materials can be supplied by agreement
Protection level: IP65、IP67
Explosion proof grade: ExibIICT3Gb，ExibIICT4Gb
Explosion proof certificate number: CELL.2152，CELL.2154
Selection Guide for Vortex Flow Meter
1、 Determine the configuration and structural form of vortex flowmeter based on the measurement medium
1. For measuring steam and gas, a split type vortex flowmeter with temperature and pressure compensation is preferred. The specific configuration includes: vortex flow sensor, intelligent flow integrator, pressure transmitter, Pt-100 platinum thermistor, and wall mounted instrument box (referred to as the five piece set). This configuration is accurate in measurement. The measurement of steam shows the compensated mass flow rate, while the measurement of gas shows the standard and operating condition volume flow rates, as shown in the following figure:
Figure 2: Split type vortex flowmeter with temperature and pressure compensation
2. When measuring steam, an integrated temperature and pressure compensation vortex flowmeter can also be used when the steam temperature is less than 200 ℃ and the diameter is not greater than DN100. At this time, the compensated mass flow rate is displayed. It is not recommended to use this type of instrument when the steam temperature is greater than 200 ℃ and the diameter is greater than DN100; When measuring gases, an integrated temperature pressure compensation vortex flowmeter can also be used, which displays the volumetric flow rate under standard and operating conditions. The integrated temperature and pressure compensation vortex flowmeter is more accurate in measurement, but its stability and reading convenience are not as good as the split type, as shown in the following figure:
Figure 3: Integrated Temperature and Pressure Compensation Vortex Flow Meter
Figure Four: Non compensating Vortex Street
Fifth, select electromagnetic flow meters for measuring tap water, sewage, acidic and alkaline liquids, electrolytes, air conditioning circulating water, etc;
6. Use elliptical gear flowmeter, waist wheel flowmeter, and turbine flowmeter for measuring diesel, gasoline, and edible oil;
7. Use a standard orifice flowmeter for measuring thermal oil.
2、 It is also necessary to determine whether the vortex flowmeter has the following functions
1. Need to provide PLC DCS、 If input signals are provided by calculators, digital displays, etc., 4-20mA current output is required;
2. To collect data on temperature, pressure, and flow meters, an RS485/RS232 communication interface is required;
3. Is it necessary to equip a wall mounted instrument box for fixing and protecting the intelligent accumulator;
4. Is it necessary to equip a backup power supply to ensure that the entire measurement system can work normally for more than 100 hours during a power outage;
5. Is remote meter reading necessary to achieve real-time monitoring of parameters such as flow rate, temperature, and pressure.
3、 Finally, it is necessary to determine the caliber of the vortex flowmeter - a flow based caliber selection method
1. The nominal diameter of a vortex flowmeter varies, and its measurement range also varies. The measurement range of each diameter also changes with the type of medium being measured, temperature, and pressure.
2. When selecting the diameter of a vortex flowmeter, one should not directly choose a flowmeter of the same diameter as the pipeline diameter, but should match the actual instantaneous flow rate with the flow range of that diameter.
3. The selection of appropriate caliber for vortex flowmeter is to solve the current measurement problem, taking into account the situation of increasing flow rate in the later stage while ensuring appropriate flow rate; Instead of the opposite, only consider the possibility of increased traffic in the future, ignoring the possibility of smaller traffic now.
When measuring saturated steam, one of the operating temperature and pressure, as well as the approximate flow range, can be determined by using the table lookup method (Tables 2 and 3) to determine the nominal diameter of the vortex flowmeter;
When measuring superheated steam, determine the operating temperature and pressure, and determine its density through the table lookup method (Table 4). Based on this density and approximate flow range, use the table lookup method (Tables 2 and 3) to determine the nominal diameter of the vortex flowmeter.
When measuring gases and liquids, first determine the approximate flow range of the medium under operating conditions, and then use the table lookup method (Table 1) to determine the nominal diameter of the vortex flowmeter.
Typical Temperature and Pressure Compensation Five Piece Vortex Flow Meter Configuration and Selection
Example 1: The inner diameter of the process pipeline is DN100, and the measurement medium is superheated steam. The steam consumption is approximately 0.6t/h-3t/h, the gauge pressure is 0.7MPa, and the temperature is 180 ℃. It is equipped with an accumulator (with 4-20mA output), pressure transmitter, Pt-100 platinum resistor, instrument box, and instrument model selection.
Solution: Based on the gauge pressure of 0.7 MPa and temperature of 180 ℃, according to the "LUGB Series Vortex Flow Meter Selection and Use Manual", it is known that the standard flow range of DN100 vortex flow meter is 0.4t/h-4 t/h, which meets the requirements of flow rate. Therefore, the nominal diameter of the instrument selected is DN100.
DN100 Vortex Flow Meter Model: LUGB-+1DAM0P1T1
If the steam consumption is approximately 0.3t/h-2t/h, a vortex flowmeter with a diameter of DN80 should be selected, and it should be locally reduced in diameter for installation.
If the steam consumption is approximately 0.6t/h-5t/h, a vortex flowmeter with a diameter of DN125 should be selected, and local expansion installation should be carried out.
Example 2: The tested medium is compressed air with a gauge pressure of 0.2MPa and a temperature of 60 ℃. The process requires a gas consumption of 300Nm3/h-1500Nm3/h, equipped with an accumulator (with RS485 interface), pressure transmitter, Pt-100 platinum resistor, instrument box, and instrument diameter and model selection.
Solution: According to the gauge pressure of 0.2MPa, temperature of 60 ℃, and process gas consumption of 300-1500Nm3/h, the operating flow range of the gas is calculated to be 123-618m3/h according to the "LUGB Series Vortex Flow Meter Selection and Use Manual". At the same time, according to Table 2 of the selection and use manual, the standard range of the DN80 vortex flow meter is 70-700m3/h, which meets the requirements of the flow rate. Therefore, the nominal diameter of the instrument is selected as DN80.
DN80 Vortex Flow Meter Model: LUGB-+1DRM0P1T1
Typical Integrated Vortex Flow Meter Configuration and Selection
Example 3: The tested medium is desalinated water, with a gauge pressure of 0.7MPa and a temperature of 20 ℃. The process requires a flow rate of 30m3/h-150m3/h, using an integrated meter display and outputting 4-20mA. Select the instrument diameter and model.
Solution: According to the measured medium being desalinated water, the process requires a flow rate of 30m3/h-150m3/h. According to Table 1 of the "LUGB Series Vortex Flow Meter Selection and Use Manual", the standard range of DN100 vortex flow meter is 19-160m3/h. Therefore, the nominal diameter of the instrument is selected as DN100.
DN100 Vortex Flow Meter Model: LUGB-C01
Example 3: The tested medium is high-temperature water, with a gauge pressure of 0.6MPa and a temperature of 165 ℃. The process requires a flow rate of 30m3/h, using an integrated meter display without signal output. Select the instrument diameter and model.
Solution: According to the fact that the measured medium is high-temperature water with a temperature of 165 ℃ and the process requires a flow rate of 30m3/h, according to Table 1 of the "LUGB Series Vortex Flow Meter Selection and Use Manual", the standard range of DN50 vortex flow meter is 5-40m3/h. Therefore, the nominal diameter of the instrument selected is DN50.
DN50 Vortex Flow Meter Model: LUGB-C01
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