Flow meter for steam pipeline in chemical plant-Global supplier

No. 188 Jianshe West Road, Minqiao Industrial Concentration Zone, Taji Town, Jinhu County, Jiangsu Province

化工厂蒸汽管道流量计

1、 Overview
The steam pipeline flowmeter in chemical plants is mainly used for measuring the flow rate of steam fluid in industrial pipelines. The characteristics of intelligent vortex flowmeter are small pressure loss, large range, high accuracy, and it is almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc. when measuring volumetric flow rate under working conditions. There are no movable mechanical parts, so the intelligent vortex flowmeter has high reliability and low maintenance. The instrument parameters can remain stable for a long time. The intelligent vortex flowmeter adopts a piezoelectric stress sensor with high reliability and can operate within a temperature range of -20 ℃ to+450 ℃. It has both analog standard signals and digital pulse signal outputs, making it easy to use in conjunction with digital systems such as computers. It is a relatively advanced and ideal flow meter.
In practical applications of steam pipeline flow meters in chemical plants, large flow rates are often much lower than the upper limit value of the instrument. With changes in load, small flow rates often fall below the lower limit value of the instrument. The instrument is not working in its optimal working range. To solve this problem, it is usually necessary to reduce the diameter at the measuring point to increase the flow rate at the measuring point, and select smaller diameter instruments to facilitate the measurement of the instrument. However, this variable diameter method requires a straight pipe section with a length of 15D or more between the variable diameter pipe and the instrument for rectification, which makes processing and installation inconvenient. Our company has developed an LGZ variable diameter rectifier with a curved longitudinal section, which has multiple functions such as rectification, increasing flow velocity, and changing flow velocity distribution. Its structural size is small, only one-third of the inner diameter of the process pipe, and it is integrated with the vortex flowmeter. It not only does not require an additional straight pipe section, but also reduces the requirements for the straight pipe section of the process pipe, making installation very convenient.
For the convenience of use, the battery powered local display vortex flowmeter in the steam pipeline of the chemical plant adopts low-power high-tech. It can operate continuously for more than a year with lithium battery power supply, saving the procurement and installation costs of cables and display instruments. It can display instantaneous flow rate, cumulative flow rate, etc. on site. The temperature compensated integrated vortex flowmeter also comes with a temperature sensor, which can directly measure the temperature of saturated steam and calculate the pressure, thereby displaying the mass flow rate of saturated steam. The temperature pressure compensation integrated type is equipped with temperature and pressure sensors, which can directly measure the temperature and pressure of the gas medium for gas flow measurement, thereby displaying the standard volume flow rate of the gas.

2、 Main features

The structure is simple and sturdy, with no movable parts, high reliability, and very reliable for long-term operation

Easy to install and very convenient to maintain.

The detection sensor does not directly contact the measured medium, with stable performance and long lifespan.

The output is a pulse signal proportional to the flow rate, with no zero drift and high accuracy.

Wide measurement range, with a range ratio of up to

Less pressure loss, lower operating costs, and more energy-saving significance.

Within a certain Reynolds number range, the output signal frequency is not affected by the physical properties and composition changes of the fluid. The instrument coefficient is only related to the shape and size of the vortex generator, and there is no need to compensate when measuring the fluid volume flow rate. After replacing accessories, there is generally no need to recalibrate the instrument coefficient.

3、 Working principle

The vortex flow sensor measures flow based on the theories of Kaman and Strouhsl regarding the generation of vortices and the relationship between vortices and flow velocity. When the medium flows through a triangular cylinder at a certain speed, an alternating vortex band is generated behind both sides of the triangular cylinder, which is called the Karman vortex street (see the figure below).

Due to the alternating generation of vortices on both sides of the vortex generator, pressure pulsations are generated on both sides of the generator, resulting in alternating pressure on the detection body. The piezoelectric crystal element encapsulated in the probe generates an alternating charge signal with the same frequency as the vortex under the action of alternating stress. The amplifier amplifies, filters, shapes, and outputs a pulse signal (or converts it into a 4-20mA signal) with a frequency proportional to the medium flow rate, which is then sent to the integrator for processing, display, and control. The relationship between the release frequency of vortices within a certain Reynolds number range (2X104-7X106) and the fluid velocity v, as well as the width d of the upstream face of the vortex generator, is expressed as f=St.v/d, where St is the Strouhal number, which is a dimensionless coefficient. As long as the frequency f is accurately measured, the fluid velocity v can be obtained, and the volumetric flow rate can be calculated from v.