The working principle of a vortex flow meter is based on the principle of the von Kármán effect, which states that when a fluid flows past a bluff body (such as a triangular or diamond-shaped obstruction), alternating vortices are shed downstream of the body. Here’s a breakdown of the working principle of a vortex flow meter:
- Bluff Body Installation: A vortex flow meter consists of a bluff body, typically in the form of a solid rod or plate, which is installed in the flow path of the fluid. The bluff body creates disturbances in the fluid flow, resulting in the formation of vortices.
- Vortex Shedding: As the fluid flows past the bluff body, vortices are periodically generated on either side of the body. These vortices detach and alternate from each side of the bluff body at a frequency directly proportional to the fluid velocity. The frequency of vortex shedding is determined by the flow velocity and the size and shape of the bluff body.
- Pressure Measurement: The vortex flow meter has pressure sensors, typically piezoelectric sensors, placed on either side of the bluff body. These sensors detect the pressure fluctuations caused by the vortices shedding and passing through the sensors.
- Signal Processing: The pressure signals from the sensors are transmitted to the flow meter’s electronics for processing. The electronics track the frequency of the pressure fluctuations, which is directly related to the fluid velocity and flow rate.
- Flow Rate Calculation: Using the known relationship between the vortex shedding frequency and the fluid velocity, the flow meter’s electronics calculate the flow rate of the fluid based on the measured frequency of the pressure fluctuations. The flow meter may have a built-in calibration curve or a programmable equation to convert the frequency into a flow rate value.
- Display and Output: The calculated flow rate can be displayed on the flow meter’s local display or transmitted as an output signal, such as a 4-20 mA current signal or a digital signal (e.g., Modbus), for further processing or recording.
Applications of Vortex Flow Meters in the oil and gas industry
Vortex flow meters are widely used in the oil and gas industry for various applications due to their reliability, accuracy, and ability to measure both liquids and gases. Here are some common applications of vortex flow meters in the oil and gas industry:
- Custody Transfer: Vortex flow meters are utilized for custody transfer applications, where accurate measurement of the fluid flow is crucial for billing purposes. They are used to measure the flow of crude oil, refined petroleum products, natural gas, and other hydrocarbons during transfer between different parties or facilities.
- Wellhead Monitoring: Vortex flow meters are employed at wellheads to monitor the flow rates of oil, gas, and water from individual wells. This data is essential for production optimization, reservoir management, and well performance evaluation.
- Allocation and Production Monitoring: In oil and gas fields, vortex flow meters are used to measure and allocate the flow of fluids at various stages of production, including separators, oil and gas gathering systems, and production facilities. They provide accurate measurements for production monitoring, reservoir management, and production optimization.
- Compressed Natural Gas (CNG) Measurement: Vortex flow meters are commonly used in CNG stations to measure the flow rate of natural gas during dispensing. They ensure accurate measurement of the gas volume, enabling proper billing and inventory management.
- Pipeline Monitoring: Vortex flow meters are installed in pipelines to monitor the flow rates of oil, gas, and other fluids during transportation. They provide real-time data for pipeline operations, leak detection, and flow assurance.
- Refinery Processes: Vortex flow meters find applications in various processes within refineries, including measuring the flow of feedstocks, intermediate products, and finished petroleum products. They assist in process control, blending, and monitoring of critical flows.
- Gas Distribution: Vortex flow meters are utilized in natural gas distribution networks to measure the flow rate of gas at different stages, such as distribution pipelines, city gate stations, and industrial gas supply. They ensure accurate billing and help manage gas distribution systems effectively.
- Offshore Platforms: Vortex flow meters are commonly used in offshore oil and gas platforms for measuring the flow of hydrocarbons, seawater, and other fluids. They provide reliable and accurate measurements in challenging offshore environments.