Flowmeter challenges
Traditional mechanical flowmeters, such as differential pressure flowmeters, positive displacement flowmeters, and variable area flowmeters, are already in the stage of popularization, with fierce price competition, decreasing profit margins, less technological innovation, and relatively mature markets. . Frost & Sullivan believes that achieving product differentiation and customized production is an important breakthrough for manufacturers in the fierce competition in mature markets. Based on Frost & Sullivan's analysis of the needs of industry users, the user community expects manufacturers to provide automated equipment that will bring tangible benefits to the production process. Users will have specific requirements in the application process, such as: application in the special environment of the petrochemical industry, the need for rugged design and explosion-proof certification; user demand for Coriolis flowmeter designed for straight pipe. How to effectively obtain the actual needs of users and improve the traditional products is a challenge to the manufacturer's differentiated and customized production process.
Guiding users to accept and use new technology flow meters, such as ultrasonic flow meters, electromagnetic flow meters, and thermal mass flow meters, is another challenge for manufacturers to make the market bigger and stronger. In fact, the new technology flowmeter mentioned above has been developed and applied more than ten years ago. How to make customers realize that using the new technology flowmeter can effectively improve the production efficiency is an important issue for manufacturers.
In addition, new technology flowmeters are constantly being introduced into various industries, and fast and efficient after-sales service is also crucial for manufacturers. In particular, the use of Flowfield based on Foundation Fieldbus and Profibus PA bus has certain requirements for software technology. Effective services can provide users with more suitable solutions and close to users.
Vortex flowmeter working principle
The working principle of the vortex flowmeter is to arrange a vortex generator in the fluid, so that the vortex is alternately generated on both sides of the body, and the vortex column is asymmetrically arranged downstream of the vortex generator to generate a certain frequency, by the formula f= St*v/(1-1.27d/D)*d, (St is the Strauhal number, which is a dimensionless number, related to the vortex generator and Reynolds number; v is the flow velocity; d is the incident head width; D is the nominal diameter) to get the flow rate.
In general, the vortex flowmeter output signal (frequency) is not affected by changes in fluid properties and composition, which means that the meter factor is only related to the shape and size of the vortex generator and the Reynolds number. Its advantages are: simple and firm structure, convenient installation and maintenance; suitable for a variety of fluids, liquid, gas, steam and some mixed phases are applicable; high precision, generally up to ± 1% R; flow range is wide, up to 10 : 1 or 20:1 or more; low head loss; no zero drift; relatively cheap price; disadvantage: not suitable for low Reynolds number Re <20000, limited use of high viscosity, low flow rate, small diameter The requirements for the environment are high, and places with vibration should be eliminated as much as possible, and the upstream side needs to have a long straight pipe section; the meter factor is lower, and the larger the diameter, the lower the diameter. The signal resolution is reduced, so the aperture should not be too large, generally used in DN15~DN300mm.
Ultrasonic flowmeter classification
●Insert ultrasonic flowmeter: can be installed and maintained without stopping production. Ceramic sensors are used for non-stop production installation using dedicated drilling equipment. Generally for mono measurement, in order to improve measurement accuracy, three channels can be selected.
● Pipe-type ultrasonic flowmeter: It is necessary to cut the pipeline installation, but the subsequent maintenance can be stopped. Mono or 3-channel sensors are available.
● External clip-on ultrasonic flowmeter: capable of performing fixed and mobile measurements. It is installed with a special coupling agent (silicone rubber cured at room temperature or high-temperature long-chain polymer grease) and does not damage the pipeline during installation.
● Portable ultrasonic flowmeter: portable, built-in rechargeable lithium battery, suitable for mobile measurement, with magnetic sensor.
1, non-contact measurement method, small size, easy to carry
2, suitable for on-site measurement of various sizes of pipe sound guiding media
3, built-in nickel-metal hydride rechargeable battery working time of more than 20 hours
4, user interface is flexible, easy to use
5, intelligent on-site printing function to ensure the integrity of the flow data
6, equipped with an integrated aluminum alloy protective box, can be used in harsh outdoor environments
● Hand-held ultrasonic flowmeter: small size, light weight, built-in rechargeable lithium battery, hand-held, with magnetic sensor.
● Explosion-proof ultrasonic flowmeter: used for explosive liquid flow measurement, it is explosion-proof and intrinsically safe. That is, the converter is explosion-proof and the sensor is intrinsically safe.