Overview

The intelligent vortex flowmeter is a new type of gas flow meter developed and manufactured by our company. This flowmeter integrates flow, temperature, and pressure measurement functions into a single unit and features automatic compensation for temperature, pressure, and compressibility factor. It is an ideal instrument for gas measurement in industries such as petroleum, chemical engineering, power generation, and metallurgy.

Product Features

1. No mechanical moving parts, resistant to corrosion, stable and reliable, long service life, and requires no special maintenance during long-term operation.

2. It adopts a 16-bit computer chip with high integration, small size, excellent performance, and powerful overall functionality.

3. The intelligent flowmeter integrates a flow probe, microprocessor, pressure sensor, and temperature sensor into a single unit, adopting a built-in modular design that makes the structure more compact. It can directly measure the flow rate, pressure, and temperature of fluids and automatically tracks and compensates for changes in real time, including corrections for compression factors.

4. The dual-detection technology can effectively enhance the detection signal strength and suppress interference caused by pipeline vibrations.

5. Utilizing advanced domestic intelligent seismic-resistant technology, it effectively suppresses interference signals caused by vibrations and pressure fluctuations.

6. It employs a Chinese character dot-matrix display, offering a large number of digits and providing intuitive and convenient readings. It can directly display the volumetric flow rate under working conditions, the volumetric flow rate under standard conditions, the total accumulated volume, as well as parameters such as medium pressure and temperature.

7. Utilizing EEPROM technology, parameter settings are convenient and can be permanently saved; furthermore, historical data can be stored for up to one year.

8. The converter can output frequency pulses and 4–20 mA analog signals, and is equipped with an RS485 interface that allows direct networking with microcomputers, with a transmission distance of up to 1.2 km.

9. Alarm output for multiple physical parameters, any one of which can be selected by the user;

10. The flowmeter’s display can be rotated 360 degrees, making installation and use simple and convenient.

11. Pressure and temperature signals are input via sensors, offering high interchangeability.

12. The device has low power consumption and can be powered either by its internal battery or by an external power source.

Main uses

The intelligent vortex flowmeter can be widely used in industries such as petroleum, chemical engineering, power, metallurgy, and urban gas supply to measure the flow rates of various gases. It is currently a featured product for metering and commercial measurement in oilfield and urban natural gas transmission and distribution systems.

Structure and Working Principle

Flow meter structure

The flowmeter consists of the following seven basic components (Figure 1):

1. Vortex generator

Made of aluminum alloy, it features helical blades set at a specific angle. These blades are fixed to the front section of the converging portion of the housing, forcing the fluid to generate intense swirling flow.

2. Housing

The device itself is equipped with flanges and features a fluid passage of a specific shape. Depending on the operating pressure, the shell material can be either cast aluminum alloy or stainless steel.

3. Intelligent Flow Meter Accumulator (principle shown in Figure 3)

It consists of analog channels for temperature and pressure detection, digital channels for flow rate detection, a microprocessor unit, an LCD driver circuit, and other auxiliary circuits, and is equipped with an external signal output interface.

4. Temperature sensor

Using a Pt100 platinum resistance thermometer as the temperature-sensitive element, its resistance value has a corresponding relationship with temperature within a certain temperature range.

5. Pressure sensor

Using a piezoresistive diffused silicon bridge circuit as the sensing element, the resistance of its bridge arms undergoes a predictable change under external pressure. Consequently, under a specified excitation current, the potential difference between its two output terminals is directly proportional to the external pressure.

6. Piezoelectric crystal sensor

Installed in the throat near the expansion section of the casing, it can detect the frequency signal of vortex precession.

7. Racemizer

Fixed at the outlet section of the housing, its function is to eliminate vortex flows and thereby reduce their impact on the performance of downstream instruments.

Working principle

The flow profile of the flow sensor is similar to the shape of a Venturi tube (Figure 2). A set of helical guide vanes is installed on the inlet side. As the fluid enters the flow sensor, these guide vanes force the fluid to generate intense swirling flow. When the fluid enters the diffuser section, the swirling flow is subjected to backflow, initiating a secondary rotation and giving rise to a gyroscopic precession phenomenon of the vortex. The precession frequency is directly proportional to the flow rate and is unaffected by the physical properties or density of the fluid. By detecting the secondary rotational precession frequency of the fluid, the sensing element can achieve excellent linearity over a wide range of flow rates. The signal is then amplified, filtered, and shaped by a front-end amplifier, converting it into a pulse signal that is proportional to the flow velocity. This pulse signal, along with other detection signals such as temperature and pressure, is subsequently sent to a microprocessor for integration and processing. Finally, the measurement results—including instantaneous flow rate, cumulative flow, as well as temperature and pressure data—are displayed on an LCD screen.

Figure 2

Main Technical Parameters and Functions

Flowmeter Specifications, Basic Parameters, and Performance Indicators

Electrical Performance Indicators

Working power supply:

A. External Power Supply: +24VDC ±15%, Ripple <5%, suitable for 4–20mA output, pulse output, alarm output, RS-485, and more;

B. Internal Power Supply: 1 set of 3.6V lithium battery (ER26500). A low-voltage indicator will light up when the voltage drops below 3.0V.

Overall power consumption:

A. External power supply: <2W;

B. Internal power supply: Average power consumption of 1 mW, capable of continuous use for more than two years.

Pulse output mode:

A. Operating condition pulse signal: The operating condition pulse signal detected by the flow sensor is directly isolated and amplified via an optocoupler before being output, with a high-level voltage ≥20V and a low-level voltage ≤1V.

B. Calibration pulse signal, compatible with the IC card valve controller, with a high-level amplitude ≥ 2.8V and a low-level amplitude ≤ 0.2V. The volume represented by each pulse can be set within a range of 0.001 m³ to 100 m³. When selecting this value, please note: the frequency of the calibration pulse signal must be ≤ 900 Hz.

C. The calibration pulse signal is isolated and amplified by an optocoupler before being output, with a high-level voltage ≥20V and a low-level voltage ≤1V.

RS-485 communication (optoelectronic isolation) enables the following functions: Using the RS-485 interface, the device can be directly connected to a host computer or a secondary meter for remote transmission of medium temperature, pressure, and standard volumetric flow rate and total standard volume—after temperature and pressure compensation. The 4–20 mA standard current signal (optoelectronic isolation) is proportional to the standard volumetric flow rate, with 4 mA corresponding to 0 m³/h and 20 mA corresponding to the maximum standard volumetric flow rate (this value can be set in the primary menu). The system supports either two-wire or three-wire configurations. The flowmeter can automatically recognize the inserted current module and output the correct signal accordingly.

Control signal output:

A. Lower Limit Alarm Signal (LP): Opto-isolated, high- and low-level alarm; alarm level is adjustable; operating voltage: +12V to +24V; maximum load current: 50mA.

B. Upper Limit Alarm Signal (UP): Opto-isolated, high- and low-level alarm; alarm level is adjustable; operating voltage: +12V to +24V; maximum load current: 50mA.

C. Valve-closing alarm output (BC terminal, for IC card controller): The output is provided by a logic gate circuit. Under normal conditions, the output is at a low level with an amplitude ≤ 0.2V; when an alarm occurs, the output switches to a high level with an amplitude ≥ 2.8V, and the load resistance must be ≥ 100 kΩ.

D. Battery Undervoltage Alarm Output (BL Terminal, for IC Card Controller): The output is provided by a logic gate circuit. Under normal conditions, the output is at a low level with an amplitude ≤ 0.2V; when an alarm occurs, the output switches to a high level with an amplitude ≥ 2.8V, and the load resistance must be ≥ 100 kΩ.

Selection and Installation

Flowmeter Selection

In the selection process, two principles should be kept in mind: first, ensure production safety; second, guarantee measurement accuracy. To this end, it is essential to specify three selection parameters: the maximum, minimum, and typical flow rates for both the near and long term (primarily used to determine the nominal diameter of the instrument); the design pressure of the medium being measured (primarily used to select the instrument’s nominal pressure rating); and the actual operating pressure (primarily used to determine the pressure sensor’s pressure rating for the instrument).

a. When the measured flow rate is known to be the operating condition volumetric flow rate, you can directly select the appropriate nominal diameter based on the flow range provided in the table.

b. When the measured flow rate is known as the volumetric flow rate under standard conditions, first convert the standard-condition volumetric flow rate QN into the operating-condition volumetric flow rate Qv, and then select the corresponding nominal diameter according to the flow range specified in the technical parameter table.

c. When both flow meters of different calibers can cover the minimum and maximum volumetric flow rates, under the condition that pressure loss is acceptable, the smaller-caliber meter should be selected whenever possible.

d. Do not allow the actual minimum flow rate Qmin to fall below the lower limit of the flow rate for the selected nominal diameter flowmeter.

e. Special requirements for flow range and nominal pressure can be specified through negotiated orders.

The selection calculation formula is as follows:

In the formula: T, P, and Pa have the same meanings as above; Q represents the volumetric flow rate, and Qn represents the standard volumetric flow rate. The values of Z/Zn are listed in Table 2. Due to the relatively large calculation step size, the data in the table are for reference only. The data in the table are calculated based on a true relative density of natural gas Gr = 0.600 and mole fractions of both nitrogen and carbon dioxide equal to 0.00. When the medium pressure is below 0.1 MPa, it can be approximated by assuming Z/Zn = 1.

Factory display

Honor Show

Exhibition style