Temperature and pressure compensation rotary vortex flowmeter

1Overview

HD-LUX(W)The intelligent vortex flowmeter is a new type of gas flow meter developed by our company with leading domestic level. This flowmeter integrates flow rate, temperature, and pressure detection functions, and can automatically compensate for temperature, pressure, and compression factor. It is an ideal instrument for gas measurement in industries such as petroleum, chemical, power, and metallurgy.Can be used for various gasesGas, air, hydrogen, natural gas, nitrogen, liquefied petroleum gas, hydrogen peroxide, flue gas, methane, butane, chlorine, gas, biogas, carbon dioxide, nitrogen, acetylene, phosgene, oxygen, compressed air, argon, toluene, benzene, xylene, hydrogen sulfide, sulfur dioxide, ammonia, etc.

1.Main features of the product

No machineryMovable components, not easily corroded, stable and reliable, long service life, long-term operation without special maintenance;

adopt16A computer chip with high integration, small size, good performance, and strong overall functionality;

Intelligent flowmeter integrates flow probe, microprocessor, pressure and temperature sensors into one,Adopting a built-in combination,Make the structure more compact, allowing for direct measurement of fluid flow rate, pressure, and temperature, and automatic real-time tracking compensation and compression factor correction;

The use of dual detection technology can effectively improve the strength of detection signals and suppress interference caused by pipeline vibration;

Adopting domestically leading intelligent seismic technology, effectively suppressing interference signals caused by vibration and pressure fluctuations;

Adopting a Chinese character dot matrix display screen, it displays multiple digits and provides intuitive readingsConvenient, it can directly display the volumetric flow rate under working conditions, volumetric flow rate under standard conditions, total amount, as well as parameters such as medium pressure and temperature;

adoptEEPROMTechnology, convenient parameter settings, can be permanently saved, and can store up to one year of historical data;

The converter can output frequency pulses4～20mASimulate signals and haveRS485Interface, can be directly connected to a microcomputer network, with a transmission distance of up to1.2km；

Multiple physical parameter alarm output, which can be selected by the user as one of them;

The flowmeter head can be360Rotating degrees, easy to install and use;

Cooperate with our companyFMType data collector, capable of remote data transmission through the Internet or telephone network

Pressure and temperature signals are sensor inputs with strong interchangeability;

The whole machine has low power consumption and can be powered by internal batteries or external power sources.

IIStructure and Working Principle

1.1main purpose

Intelligent spiral vortex flowmeter can be widely used in industries such as petroleum, chemical, power, metallurgy, and urban gas supply to measure various gas flow rates. It is currently the preferred product for natural gas transmission and distribution measurement and trade measurement in oil fields and cities.

image1

1.bluff body

Made of aluminum alloy, spiral blades with a certain angle are fixed at the front of the shell contraction section, forcing the fluid to generate strong vortex flow.

⒉housing

It is equipped with flanges and fluid channels of a certain shape. Depending on the working pressure, the shell material can be cast aluminum alloy or stainless steel.

⒊Intelligent flowmeter integrator (principle diagram)3）

It consists of temperature and pressure detection analog channels, flow detection digital channels, as well as microprocessor units, LCD driver circuits, and other auxiliary circuits, and is equipped with output signal interfaces.

4. temperature sensor

withPt100Platinum resistors are temperature sensitive components, and their resistance values correspond to temperature within a certain temperature range.

5. pressure sensor

The piezoresistive diffusion silicon bridge is used as the sensitive element, and its bridge arm resistance will undergo expected changes under external pressure. Therefore, under a certain excitation current, the potential difference between its two output terminals is proportional to the external pressure.

6. Piezoelectric crystal sensor

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

⒎Racemizer

Fixed at the outlet section of the shell, its function is to eliminate vortex flow and reduce the impact on downstream instrument performance.

2.2working principle

The flow profile of a flow sensor is similar to the profile of a Venturi tube. Place a set of spiral guide vanes on the inlet side, which force the fluid to generate intense vortex flow when it enters the flow sensor. When the fluid enters the diffusion section, the vortex flow is subjected to backflow and begins to undergo secondary rotation, forming a gyroscopic vortex precession phenomenon. The precession frequency is directly proportional to the flow rate and is not affected by the physical properties and density of the fluid. By measuring the secondary rotation precession frequency of the fluid with the detection element, good linearity can be obtained over a wide range of flow rates. The signal is amplified, filtered, and shaped by a preamplifier into a pulse signal proportional to the flow rate, and then sent to the microprocessor for integration processing along with temperature, pressure, and other detection signals. Finally, the measurement results are displayed on the LCD screen(Instantaneous flow rate, cumulative flow rate, temperature, and pressure data).

2.3Working principle of flow integrator

The flow integrator consists of temperature and pressure detection simulation channels, flow sensor channels, and microprocessor units, and is equipped with external output signal interfaces to output various signals. The microprocessor in the flowmeter compensates for temperature and pressure according to the gas equation, and automatically corrects the compression factor. The gas equation is as follows:

………………(2)

Where:

Q_N——Volume flow rate under standard conditions(m³/h)；

Q_V——Volume flow rate under operating conditions(m³/h；

Pa ——Local atmospheric pressure（KPa）；

P ——The gauge pressure measured by the pressure tapping hole of the flowmeter（KPa）；

P_N——Atmospheric pressure under standard conditions（101.325 KPa）；

T_N——Absolute temperature under standard conditions（293.15K）；

T ——Absolute temperature of the measured fluid（K）；

Z_N——The compression coefficient of gas under standard conditions;

Z ——The compression coefficient of gas under working conditions;

Note: When calibrating with a bell jar or negative pressure, takeZ_N/Z=1Regarding natural gas(Z_N/Z)^1/2=F_ZFor the supercoressure factor. According to the standards of China National Petroleum CorporationSY／T6143－1996Calculate the formula in.

IIIMain technical parameters and functions

3.1Flow meter specifications, basic parameters, and performance indicators (see table)1）

(Table)1）

Note:1.Accuracy: refers to the system accuracy after temperature and pressure correction;

2. ATheBUsed to distinguish between different flow ranges of the same diameter.

3.2Standard state conditions:P=101.325KPa，T=293.15K

3.3Usage conditions:

Ambient temperature-30℃～+65℃

Relative humidity:5%～95%

Medium temperature:-20℃～+80℃

Atmospheric pressure:86KPa～106KPa

3.4Electrical performance indicators

3.4.1Working power supply:

AExternal power supply:+24VDC±15%Ripple<5%, applicable to4～20mAOutput, pulse output, alarm outputRS-485Wait;

BInternal power supply:1group3.6VLithium battery（ER26500）When the voltage is lower than3.0VWhen there is an undervoltage indication.

3.4.2Whole machine power consumption:

AExternal power supply:<2W;

BInternal power supply: average power consumption1mWCan be used continuously for more than two years.

3.4.3Pulse output mode:

APulse signal for operating conditions, directly isolate and amplify the pulse signal detected by the flow sensor through optocoupler, and output it at high level≥20V, low level≤1V；

B． Calibration pulse signal, andICCard valve controller matching, high level amplitude≥2.8VLow level amplitude≤0.2V， The unit pulse represents a volume that can be set within the following range:0.001m³~100m³When selecting this value alone, it must be noted that the frequency of the calibration pulse signal should≤900Hz.

CCalibration pulse signal, isolated and amplified by optocoupler, high level output≥20V, low level≤1V.

3.4.4 RS－485Communication (optoelectronic isolation) can achieve the following functions:

A. AdoptingRS－485Interface, which can be directly connected to the upper computer or secondary meter to remotely display the temperature, pressure, and standard volume flow rate and total standard volume after temperature and pressure compensation of the medium;

BFromRS－485Interface andHW－ⅠThe data collector is compatible and can form a telephone network communication system. One data collector can be equipped with15Flow meter;

CFromRS－485Interface andHW－ⅡThe data collector is compatible and can form a broadband network communication system, consisting ofINTERNETData transmission, one data collector can carry8A flow meter.

3.4.5 4～20mAStandard current signal (photoelectric isolation)

Directly proportional to the standard volumetric flow rate,4mAcorrespond to0 m³/h，20 mACorresponding to the maximum standard volume flow rate (which can be set in the first level menu), the system is either two-wire or three wire. The flowmeter can automatically identify and output correctly based on the inserted current module.

3.4.6Control signal output:

ALower limit alarm signal（LP）Optoelectronic isolation, high and low level alarm, alarm level can be set, working voltage+12V~+24V, maximum load current50mA；

BUpper limit alarm signal（UP）Optoelectronic isolation, high and low level alarm, alarm level can be set, working voltage+12V~+24V, maximum load current50mA；

CValve closing alarm output（BCEnd,ICUsed for card controller: logic gate circuit output, normal output low level, amplitude≤0.2VAlarm output high level, amplitude≥2.8V,load resistor≥100kΩ；

DBattery undervoltage alarm output（BLEnd,ICUsed for card controller: logic gate circuit output, normal output low level, amplitude≤0.2VAlarm output high level, amplitude≥2.8V,load resistor≥100kΩ；

3.5Real time data storage function

3.5.1In order to meet the needs of data management, the flowmeter has added real-time data storage function, and one of the following three options can be selected by setting:

AStart stop record: Recent1200Record the start stop time, total amount, and net flow rate. Factory default settings. The corresponding communication protocol will be provided separately by the company;

BDiary entry: Recently920Record the date of the day, temperature at midnight, pressure, standard volume flow rate, and total amount.

CRecord at regular intervals:1200Record the date, time, temperature, pressure, standard volume flow rate, and total amount of the specified time interval.

3.5.2The above stored data can be read through a computer to form data reports and curve graphs for analysis.

3.6Network communication management software functions

The flowmeter is matched with a data collector and can communicate through telephone lines or broadband networks to read and set the historical data and parameters of each flowmeter in the network. At the same time, the communication management software can achieve comprehensive management functions.

3.7Explosion proof mark:ExdIIBT4; ExiaIICT4

3.8Protection level:IP65

3.9pressure loss

The calculation formula for the actual pressure loss of the flowmeter is as follows:

…………………(1)

Where:

ΔP₁——Actual pressure loss of flowmeter（KPa）；

ρ ——Density of the tested medium（kg/m³）

ΔP –Pressure loss of flowmeter when the medium is dry air(KPa),Its characteristic curve is shown in the following figure

3.10Wiring port: The outgoing port isM20×1.5Internal thread.