越来越广泛地应用于工业生产中的各种流体介质的检测。 With the advancement and development of detection technology and manufacturing technology, pressure-sensitive strain gauge target flow meters are more and more widely used in the detection of various fluid media in industrial production. It has the characteristics of sturdy structure, small resistance drop, less leakage points than other flow meters, high measurement accuracy and sensitivity, and easy maintenance. The torch chemical plant has special process media and has high requirements for the reliability and leakage prevention of the flow meter. The plant used about 70 WFV series pipeline and plug-in target flow meters from the American Welkin Company in its expansion project in 2001. , Mainly used for the measurement of process media, water and steam and other media.
1 Causes of errors
During the commissioning of the new device in 2002, the experience of using some target flowmeters was summarized. After the target type flowmeter is installed in accordance with the technical conditions, the target type flowmeter is calibrated according to the design requirements when it leaves the factory. It is put into operation according to the operating steps. It is found that a small number of meters display a large error and some alarms show full scale. Disassembled at the site and verified by removing the weight and finding that the flowmeter is good. After analysis, the main reasons are as follows.
1 Some large debris in the fluid is wound on the target rod, and it is easy to indicate the full range under the state of flow. This phenomenon mainly exists in the measurement of circulating water, which is due to the direct extraction of river water without filtering.
的靶板位于管道中心，也不能保证靶板完全垂直于管道。 2 Due to installation errors, the target plate of all plug-in target flowmeters cannot be guaranteed to be located in the center of the pipeline, nor can the target plate be completely perpendicular to the pipeline. Therefore, there is a difference between the operating conditions and the calibration conditions before leaving the factory, which causes a measurement error of the target flow meter.
In view of the above reasons, considering that the plant's flow measurement points are not bypassed to reduce leakage points and reduce investment, the plant has formulated the following solutions.
1 In order to prevent larger debris in the fluid from getting entangled with the target plate rod, a filter screen is installed at the pump outlet to filter out these larger debris.
2 Use the comparison method to correct the error of the target flowmeter at the production site. The instrument used: a 4 and a half digital multimeter; a portable ultrasonic flowmeter; necessary wiring clamps and tools.
The specific operation steps are described below.
First install the portable ultrasonic flowmeter according to the requirements. Pay special attention to the electrodes installed, and calibrate and adjust the ultrasonic flowmeter. Then check the target flowmeter installed in place with a digital multimeter according to the calibration book provided by the factory to check and adjust the zero position, range, damping, etc., and finally set the work switch to the measurement position.
SBL type intelligent target flowmeter is based on the original strain gauge target flowmeter measurement principle, using the latest capacitive force sensor as a measurement and sensitive transmission element, while using modern digital intelligent processing technology and developed New flow meter.
Capacitive force sensor is the key to the high precision and stability of this new product, which is incomparable with the original strain gauge force sensor. 无可动部件的特点,同时又具有与容积式流量计相媲美的测量准确度,加之其特有的抗干扰、抗杂质性能,除能替代常规流量所能测量的流量计量问题,尤其在小流量、高粘度、易凝易堵、高温、强腐蚀、强震动等流量计量困难的工况中具有很好的适应性。 It has the characteristics of traditional orifice plate and target type flowmeters without moving parts, and has measurement accuracy comparable to volumetric flowmeters.In addition, it has its unique anti-interference and anti-impurity performance. Measurable flow measurement problems, especially in small flow, high viscosity, easy to set, easy to plug, high temperature, strong corrosion, strong vibration and other difficult flow measurement conditions have good adaptability. Has been widely used in metallurgy, petroleum, chemical, energy, food, environmental protection and other fields of flow measurement.
Scope of application:
● Applicable to various nominal diameters: from DN15 to DN2000mm to larger;
● Suitable for high and low temperature media: from -40 ℃ ～ + 260 ℃; higher temperature is negotiated with the manufacturer;
● Applicable to low, medium and high pressure working conditions: from 0 to 42Mpa (gauge pressure);
With a variety of installation methods to choose from, such as online plug-in, low installation costs;
With integrated temperature and pressure compensation, direct output quality or standard;
With optional small signal removal, non-linear correction, and filtering time can be selected;
Can accurately measure the gas and liquid flow under various normal temperature, high temperature and low temperature conditions;
Very high sensitivity, can measure ultra-small flow rate, and its measurable low flow rate is 0.08m / s;
● No moving parts, safe and reliable use;
Accurate measurement, accuracy can reach 0.2%;
● Wide measurement range, the maximum measurement range can reach 20: 1 (liquid) or 10: 1 (gas);
● Good repeatability, generally 0.05 ～ 0.08%, fast measurement;
Low pressure loss, only about 1/2 △ P of standard orifice plate;
● Excellent anti-interference and anti-impurity capabilities;
● Easy to calibrate. Dry calibration method can be adopted, that is, weight hanging method. One-button operation can complete the calibration;
Change the flow range according to actual needs;
Low-power battery on-site display, which can directly read the displayed value online, and the display screen can simultaneously read the instantaneous and cumulative flow and percentage bar graph
● Using the latest GPRS wireless remote transmission technology, especially suitable for field measurement;
Simple and convenient installation and easy maintenance;
Multiple output formats, which can transmit various parameters remotely;
Strong vibration resistance, pulsating flow can be measured within a certain range;
● The instrument has a self-checking program, and the failure phenomenon is clear at a glance.