Scraper flowmeters are commonly used in crude oil transfer trades
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With the continuous advancement of economic globalization, crude oil, as a commodity, is increasingly participating in the international trade market. As an important aspect of crude oil transfer transactions, the measurement and handover of crude oil is receiving increasing attention. The accuracy of measurement in crude oil trade transfers affects the economic benefits of various parties involved, including suppliers, sellers, and transporters. A scraper flow meter is a commonly used device for measuring and transferring crude oil. A paddle flow meter uses mechanical measuring elements to continuously divide the flowing liquid into individual volume portions in order to measure the total volume of the liquid; it is currently widely used for measuring petroleum products in China.
【Ten Years of Rapid Development in Chemical Engineering Equipment】Domestic production of scraper flow meters for large-diameter crude oil pipelines from 2015 to 2023 https://bbs.hcbbs.com/thread-4346279-1-1.html (Source: Haichuan Chemical Engineering Forum)
The core structural components of a scraper flowmeter include an upper cover, a metering chamber, a cam, rollers, an inner shell, a rotor body, scrapers, bearings, a gear set, a device error adjuster (precision corrector), a counter, and a gauge face. After precise machining, the scraper flow meter enables a metering chamber with an exact volume to be formed between the upper cover, the inner shell, the scraper, and the rotor. As the rotor on the ball bearing drives the scraper to rotate, a fixed volume of crude oil medium is discharged. The gear set transmits the number of rotations of the scraper to the gauge, and the counter on this gauge converts the number of rotations into the actual measured volume, thereby enabling the measurement of the volume of the crude oil medium. Flow meters with remote pulse output convert mechanical rotation into pulse signals through electromagnetic induction; by determining the number of pulses emitted by the flow meter along with the corresponding gauge factor, it is possible to determine the volume of liquid that has passed through it. Scraper flow meters feature high measurement accuracy; their metering properties are generally not affected by the state of the fluid, nor are they restricted by the Reynolds number. Additionally, their bearings and scrapers are resistant to wear, corrosion, and sand intrusion, and they offer good stability.
The factors that affect the accuracy of scraper flow meters include medium temperature, medium viscosity, instrument vibration, and wear of the metering chamber. The higher the temperature, the lower the viscosity, and the greater the leakage ； The lower the temperature, the greater the viscosity and the smaller the leakage. Wear of the metering chamber leads to an increase in the leakage rate of the scraper gauge, which in turn causes a \"negative\" change in the measurement error. Using a volumetric tube for the online calibration of slide gate flow meters allows for accurate real-time calibration of these meters, without affecting the measurement results of crude oil transfers. It also reduces the costs associated with the disassembly and transportation of slide gate flow meters, prevents potential damage, and thus maximizes the economic benefits for businesses.
It belongs to the category of positive-displacement flow meters; its advantages include high precision, a relatively larger size (due to considerations related to flow rate and strength), and its cost is generally higher than that of other flow meters of the same type.