是一种新型的插入式差压流量计.在管道中插入一根威力巴探头,当流体流过探头时,在其前部形成一个高压分布区,在其后部形成一个低压分布区,如图所示.在探头杆上有按一定规则排列的多对(3-5对)取压孔,分别感测流体的全压力(静压力与平均速度压力之和)P1和静压力P2,将P1T P2分别导入差压变送器,测出差压△P=P1-P2,△P反映了流体平均速度,流体流量Q与△P成比例,流量公式为: Verabar flowmeter is a new type of plug-in differential pressure flowmeter. A Verabar probe is inserted into the pipeline. When the fluid flows through the probe, a high-pressure distribution area is formed at the front and a low-pressure is formed at the rear. The distribution area is shown in the figure. There are multiple pairs (3-5 pairs) of pressure-receiving holes arranged on the probe rod according to a certain rule, which respectively sense the total pressure of the fluid (the sum of the static pressure and the average velocity pressure) P1 and static pressure. Pressure P2, P1T P2 are respectively introduced into the differential pressure transmitter, and the differential pressure is measured △ P = P1-P2, △ P reflects the average velocity of the fluid, the fluid flow rate Q is proportional to △ P, and the flow rate formula is:
This flowmeter consists of Verabar probe, differential pressure transmitter and flow totalizer (display adjustment) .It is a flow measurement system.It can be networked with the control system and computer.For compressed fluids such as gas and steam, temperature and temperature can be added if necessary. Pressure compensation to improve measurement accuracy.
I. Main Features
1. The cross-sectional shape of the probe is bullet-shaped, which conforms to the principle of fluid dynamics. The differential pressure signal generated is stable, the pressure measuring hole is not easy to block, and the measurement accuracy is high. 2. The probe structure adopts the overall dual cavity structure, which is firm and reliable, resistant to high temperature, high pressure and corrosion. 3. The installation requires a short straight pipe section, and the probe is inserted into the pipeline, which is convenient to install and can be continuously installed. 4. The pressure loss of the probe is small, only 3-5% of the pressure loss of the orifice plate, which is an excellent energy-saving flow meter. 5. Small application range: It can be used to measure the flow of gas, steam, coal vapor and various liquids. It can be used for round tubes and rectangular tubes of various sizes. It can be used in high temperature and high pressure, corrosive occasions.
概述 Overview of Verabar Flowmeter
The most advanced differential pressure flow measurement technology
The XD-HLV Veribar flowmeter uses an engineering structure design that fully complies with the aerodynamic principle. It is a sensing element that has achieved unparalleled levels of accuracy, efficiency and reliability.
1, Verabar flowmeter uses
XD-HLV Veribar flowmeter is suitable for high-precision flow measurement of gas, liquid and steam. Verabar is a differential pressure, rate average flow sensor, which measures the flow through the differential pressure generated by the sensor in the fluid. Verabar reflects the true flow velocity of the fluid, with an accuracy of ± 1.0 and repeatability of ± 0.1. The outstanding advantage of Verabar is: output a very stable, pulse-free differential pressure signal
2.Design characteristics of the probe
The probe with a cross-sectional shape of the bullet head can produce accurate pressure distribution and a fixed fluid separation point; the low-pressure pressure taking holes located on the two sides behind the probe side and before the fluid separation point can generate a stable differential pressure signal and effectively prevent blockage. The internal integrated structure can avoid signal leakage, improve the structural strength of the probe, and maintain long-term high accuracy.
3. Veribar probe anti-blocking design With its excellent anti-blocking design, the Veribar flow probe completely eliminates the shortcomings of plug-in flow probes such as Annubar. the height of.
The high-pressure pressure taking hole of the probe will not be blocked by the front of the probe to form a high-pressure area. The pressure is slightly higher than the static pressure of the pipeline, which prevents particles from entering. Please note: The velocity of the fluid at the probe's high-pressure tapping hole is zero, and no objects will enter the tapping hole. When the machine is turned on, the fluid enters the elbow under the static pressure of the pipeline, and a pressure equilibrium state is quickly formed. When the pressure equilibrium state is formed, the fluid encounters high pressure at the inlet of the elbow, detours, and no longer enters the elbow.
4. Advantages of the probe
● It can measure a variety of media and has a wide range of applications
● High accuracy and large range ratio
● The probe taking pressure hole is essentially anti-blocking
● The measurement signal is stable and the fluctuation is small
● Low permanent pressure loss of the pipeline
● Unique high-strength bullet-shaped single-piece dual-cavity structure
● Low installation cost and basically maintenance-free
● Can be installed and repaired online
5. Characteristics of Verabar averaging tube flow sensor
● Stable signal
Verabar's low-pressure tapping holes are located on the back two sides of the probe side, between the fluid and the probe separation point, away from the vortex wave area.
● Excellent long-term high accuracy
Verabar can guarantee long-term stability of accuracy because:
⑴. It is not affected by abrasion, dirt and oil.
⑵. There are no moving parts in the structure.
⑶. The occurrence of blockage is excluded from the design. At the front of the probe, a high static pressure area surrounds the probe so that the high-pressure pressure taking hole will not be blocked. The most important thing is that the low-pressure holes are taken at the back two sides of the probe side, and the fluid is swept across the surface, which protects the low-pressure holes from being swept, and other probes are easily blocked because their low-pressure pressure holes are collected by impurities. Low voltage fluctuation area.
● Lowest installation cost
⑴. It only needs a few inches of line welding, and the installation is very simple and fast.
⑵. Apply special tools to achieve online installation with pressure.
⑶. All valves and interfaces of various instruments need only simple assembly, which requires very low assembly costs.
● Very low operating costs
⑴. It is a non-constrictive design. As a plug-in flow probe, Verabar has the lowest operating cost.
威. Verabar flowmeters only produce very low permanent pressure losses, typically less than 0.7KPa
⑶. The permanent pressure loss generated by an orifice plate element exceeds 14KPa
⑷. Compared with the orifice plate, Verabar's energy loss is reduced by 95%.
● The continuous operation of Verabar basically eliminates the possibility of clogging, but in the following cases, Verabar still needs to pay attention to the clogging:
⑴. When the impulse tube leaks and the high-pressure balance area of the probe is damaged, particles with a smaller diameter among impurities may enter
⑵. When the pipeline is stopped, due to the Brownian motion of the molecules, small particles of impurities may enter the pressure taking hole.
⑶. The system frequently starts and stops. At the moment when the high-pressure area is formed, small particles of impurities may enter the pressure taking hole. Over time, the probe may be blocked.
⑷. The medium contains a large amount of tar, algae, or contains fibrous substances, which may also cause the probe to be blocked.
6. Apply new technologies
The original design of the valve joint with valve .. The new design concept provides a new concept.
1. Make installation and maintenance easier.
2. Reduce the number of assembly parts and connect the hardware
Fast installation system
Quick insertion and removal
● Sealed drive system prevents damage to components
● Can be applied to the installation of multiple probes
Full installation within 1 hour
主要技术指标 Third, the main technical indicators of Verabar flowmeter
1. Performance index of Verabar flow measurement system
Measurement accuracy: ± 1 Repeat accuracy: ± 0.1
Applicable pressure: 0 ～ 40MPa Applicable temperature: － 180 ℃ ～ ＋ 550 ℃
Upper measurement limit: Depends on probe strength. Lower measurement limit: Depends on minimum differential pressure measurement.
Range ratio: greater than 10: 1
Applicable pipe diameter: 38mm ～ 9,000mm round pipe, square pipe
Applicable medium: full pipe, one-way flow, one-way gas, steam and liquid with a viscosity of not more than 10 centipoise
Verabar has a wide range of uses, it is widely used in a variety of
Vapor measurement, the following is the typical application medium.
Gas / liquid / steam
Natural gas / cooling water / saturated steam
Compressed air / boiler water / superheated steam
Gas / Desalination
Gas hydrocarbons / liquid hydrocarbons
Hot Air / Cryogenic Liquid
Generator gas / thermal fluid
Introduction to the working principle of Verabar flowmeter
When fluid flows through the probe, a high-pressure distribution area is created in the front of the probe, and the pressure in the high-pressure distribution area is slightly higher than the static pressure of the pipeline. According to the principle of Bernoulli's equation, when the fluid flows through the probe, the speed increases, and a low-pressure distribution area is generated at the rear of the probe. The pressure in the low-pressure distribution area is slightly lower than the static pressure of the pipeline. After the fluid flows through the probe, a partial vacuum is created at the back of the probe, and vortices appear on both sides of the probe. The cross-sectional shape of the average velocity flow probe, the surface roughness, and the location of the low pressure pressure taking hole are the key factors that determine the performance of the probe. The stability and accuracy of the low-voltage signal play a decisive role in the accuracy and performance of the average speed probe. Verabar's average velocity flow probe can accurately detect the average differential pressure produced by the average velocity of the fluid. The Verabar average velocity flow probe has multiple pairs of pressure taking holes arranged according to certain criteria in the high and low pressure areas, making it possible to accurately measure the average flow velocity.
Five, Verabar flowmeter measurement principle
XD-HLV Verabar flowmeter is a plug-in flow measurement instrument. A Verabar sensor is inserted in the pipeline. When the fluid flows through the sensor, a high-pressure distribution area is generated in the forward flow direction of the sensor and a low-pressure distribution area is generated at the rear. The sensor has a plurality of pairs of pressure-receiving holes arranged in a certain rule in the high and low pressure regions, and generally measures the total pressure of the fluid, including the static pressure and the average velocity pressure Pl and the static pressure P2. Introduce P1 and P2 to the differential pressure transmitter respectively, and measure the differential pressure △ P = P1-P2. △ P reflects the average velocity of the fluid, so that the flow rate of the fluid can be calculated.
Technical parameters and applications
Operation and Maintenance of Verabar Flowmeter
1. Preparations before commissioning
① The sensor is installed correctly:
After the sensor is installed on the pipeline, it must be carefully inspected before commissioning. It is required that the welding is firm, the direction is correct, it is strictly non-leaking, and the insertion depth is appropriate.
② Instrument adjustment:
Sensors are equipped with differential pressure transmitters and intelligent flow totalizers (may also have pressure transmitters and temperature transmitters). They must be inspected and adjusted before they can be put into use. The measuring range of the instrument must meet the requirements of the sensor and the measured medium. For example, the measured maximum air flow Qmax = 5000m3 / h, and the maximum differential pressure generated by the sensor is calculated.
△ Pmax = 0.6Kpa, the measurement range of the differential pressure transmitter should be adjusted to 0 ~ 0.6KPa, corresponding to output 4 ~ 20mADC current signal. For a general-purpose flow totalizer, you should program and configure the input totalizer according to the real-time flow range, differential pressure range, medium density, temperature, pressure, and flow calculation requirements, and make sure that the totalizer can correctly calculate and display flow.
③ Instrument wiring is correct:
Sensors and differential pressure transmitters, flow totalizers, etc. constitute a measurement system, supporting power lines of the instrument, signal output and input lines between the instruments, control and alarm connections, etc., on the terminal boards of each instrument (also known as terminals There is a clear mark on the board, and it must be correctly identified and selected for use. The instrument wiring must be checked repeatedly before commissioning. In order to make preparations for commissioning, in addition to carefully reading the "Verabar Flowmeter Instruction Manual", you should also read the "Differential Pressure Transmitter Operation Manual" and the "Smart Flow Totalizer Operation Manual" and follow the instructions. The guide to work.
2. Operation of flowmeter
① The measurement system is closed:
The preparation for commissioning has been completed, the measured medium is full of process pipeline flow, and the sensor measurement system is temporarily closed. At this time, the balance valve of the three valve group should be opened, and the high pressure valve P l and the low pressure valve P2 should be closed. The supporting instrument is in the power supply state, and warms up for about 15 minutes.
② The measurement system is turned on:
After the instrument warms up, turn on the measurement system. Open the Pl and P2 valves on the three-valve, the balance valve is still open. At this time, the differential pressure transmitter has been filled with the measured medium (gas or liquid), opened the drain valve on the transmitter, and quickly drained off the dirty liquid or gas and closed. Then close the balance valve on the three valve group, and the transmitter will enter the differential pressure measurement state. The signal current I △ P corresponding to the differential pressure △ P is output. From the signal current value (m A), the differential pressure △ P value (KP a) can be calculated. The flow totalizer also enters the working state and displays the flow rate of the measured medium.
If all the above work is successful and the flowmeter works normally, the commissioning work will be completed and delivered to production.
3.Maintenance of flow meter
Verabar flowmeters require less maintenance and Verabar integrated sensors are maintenance-free. The daily maintenance of the supporting secondary meter is very small, and only the routine maintenance such as zero check and span test is needed. However, in some cases, when the conditions of use of the measured medium deviate significantly from the design conditions, some field parameter corrections and other work are required. Here are a few cases:
① The production process is discontinuous and occasionally stops and opens. Pay attention to flowmeter maintenance. When the production process is stopped, the balance valve of the three valve group should be opened, the high pressure valve P l and the low pressure valve P2 should be closed, and the differential pressure transmitter should be in a state without differential pressure input. When the production process resumes, P 1 and P 2 should be opened again. Close the balance valve, and the differential pressure transmitter resumes the measurement state with differential pressure input.
② For some test media with a large amount of dust, such as crude gas (not cleaned), industrial water (containing sand), humid gas (containing dust), etc., it is expected that the probe's pressure hole may be blocked at regular intervals. . In the blowing method, compressed air is introduced into the sensor to blow back the dust particles on the high-pressure holes and low-pressure holes to prevent clogging. Each purge time does not exceed 30 seconds. During this time, the pressure piping to the differential pressure transmitter should be closed, and then reopened after purge. In some cases where compressed air is not allowed to be blown in, such as high temperature gas, steam can be used for blowing.