Dynamics Of Flow Metering

Flow measurement is vital to many different industries such as oil and gas, power, water and waste treatment. These industries require that they know exactly how much fluid is passing through a point at any given point.

A flow meter is an instrument used to measure linear, non-linear, mass or volumetric flow rate of a liquid or gas.

Important questions that can help determine the flow meter type required for different applications are as follows;

  • The type of fluid being measures
  • Expected temperature of fluid
  • Maximum expected pressure at a location
  • How accurate the meter should be
  • Size of pipe the flow meter will be installed on

There are many different flow meters types and each performs optimally under different conditions.  The most important part to choosing a flow meter is to have a clear understanding of the particular applications requirements. In here we will be mentioning just a few of the flow meters which are;

 

TURBINE FLOW METER:

Turbine flow meter is the most popular equipment to measure flow electronically. They offer a wide flow and application range. Turbine flow meters are easy to maintain, Long-lasting & versatile. In order of magnitude from largest to smallest, these are used in oil and gas, water and wastewater, gas utility, chemical, power, food and beverage, aerospace, pharmaceutical, metals and mining, and pulp and paper.

HOW TURBINE FLOW METERS WORK

Turbine flow meters use the mechanical energy of the fluid to rotate a “pinwheel” (rotor) in the flow stream. Blades on the rotor are angled to transform energy from the flow stream into rotational energy. The rotor shaft spins on bearings. When the fluid moves faster, the rotor spins proportionally faster. Turbine flow meters now constitute 7% of the world market.

Shaft rotation can be sensed mechanically or by detecting the movement of the blades. Blade movement is often detected magnetically, with each blade or embedded piece of metal generating a pulse. Turbine flow meter sensors are typically located external to the flowing stream to avoid material of construction constraints that would result if wetted sensors were used. When the fluid moves faster, more pulses are generated. The transmitter processes the pulse signal to determine the flow of the fluid. Transmitters and sensing systems are available to sense flow in both the forward and reverse flow directions.

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A Turbine flow meter

 

CORIOLIS MASS FLOW METER

Coriolis Mass flow meter is a device that measures mass flow rate of a fluid traveling through a tube. The mass flow rate is the mass of the fluid traveling past a fixed point per unit time.

CORIOLIS MASS FLOW METER WORKING PRINCIPLE

There are two basic configurations of coriolis flow meter: the curved tube flow meter and the straight tube flow meter. This article discusses the curved tube design

Fluid is being pumped through the mass flow meter. When there is mass flow, the tube twists slightly. The arm through which fluid flows away from the axis of rotation must exert a force on the fluid, to increase its angular momentum, so it bends backwards. The arm through which fluid is pushed back to the axis of rotation must exert a force on the fluid to decrease the fluid’s angular momentum again; hence that arm will bend forward. In other words, the inlet arm (containing an outwards directed flow), is lagging behind the overall rotation, the part which in rest is parallel to the axis is now skewed, and the outlet arm (containing an inwards directed flow) leads the overall rotation.

 

ULTRASONIC FLOW METER

An ultrasonic flow meter is a type of flow meter that measures the velocity of a fluid with ultrasound to calculate volume flow. Using ultrasonic transducers, the flow meter can measure the average velocity along the path of an emitted beam of ultrasound, by averaging the difference in measured transit time between the pulses of ultrasound propagating into and against the direction of the flow or by measuring the frequency shift from the Doppler Effect

ULTRASONIC FLOW METER WORKING PRINCIPLE

The basic principle of operation employs the frequency shift (Doppler Effect) of an ultrasonic signal when it is reflected by suspended particles or gas bubbles (discontinuities) in motion. This metering technique utilizes the physical phenomenon of a sound wave that changes frequency when it is reflected by moving discontinuities in a flowing liquid. Ultrasonic sound is transmitted into a pipe with flowing liquids, and the discontinuities reflect the ultrasonic wave with a slightly different frequency that is directly proportional to the rate of flow of the liquid. Current technology requires that the liquid contain at least 100 parts per million (PPM) of 100 micron or larger suspended particles or bubbles.  

 

VORTEX FLOW METER

Another method of flow measurement involves placing a bluff body in the path of the fluid. As the fluid passes this bar, disturbances in the flow called vortices are created. The vortices trail behind the cylinder, alternatively from each side of the bluff body. The frequency at which these vortices alternate sides is essentially proportional to the flow rate of the fluid. Inside over, or downstream of the shedder bar is a sensor for measuring the frequency of the vortex shedding.

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A Vortex Flow Meter

 

INSTALLATION, MAINTENANCE & CALIBRATION

GIL Automations Limited in collaboration with our technical partners supports our customers with design and specifications for flow meters as per customers’ requirements.

We also provide primary and secondary calibration services for flow meters. Our calibration procedures are in line with ISO 17025 requirements. We are certified by local standard boards and we provide primary metering systems for proving meters and for calibrating measurement devices.

Our procedures comply with the American Petroleum Institute (API) Manual of Petroleum Measurement Standards

(MPMS) guidelines, especially such as:

  1. Gravimetric Method API MPMS 4.9.3
  2. Master Meter Method API MPMS 4.9.4
  3. Water Draw Method API MPMS 4.9.2
  4. Calculation of Petroleum Quantities API MPMS 12.2.2
  5. DPR Guide 2.5.3

We offer on-site and in-house flow meter calibration for a wide range of petroleum-based products, up to 5000 liters per minute. Our truck-mounted volumetric proving vessels are available for on-site flow meter calibration of light petroleum products and some chemicals. All proving vessels are traceable to NIST and re-certified yearly. Calibrations are performed according to NIST Handbook 44 guidelines.

We have prover tanks from Seraphinn in US for range from 500 litres per minute up to 5000 liters per minute. Our Offshore skid has a prover tank (primary standard) and a master meter (secondary standard) on board in line with DPR requirements.

Some of the equipment we certify includes:

  • Flow meters (PD Meters, coriolis mass meters, turbine meters etc.)
  • Metering systems such as provers (using master meters and provers), custody transfer meters etc.
  • We also lease our equipment for mobile offshore use.

We have deployed Laboratory information management system (LIMs) to meet the requirements of our clients.

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