Versatile applications and types of electromagnetic flowmeter

Versatile applications and types of electromagnetic flowmeters:

Electromagnetic flowmeters are one of the most versatile flowmeters. They can measure liquids, vapors and gases with relative ease. One reason they are widely used for steam flow measurement is their ability to withstand the high temperatures of steam. Steam is the most difficult fluid to measure. This is due to the high pressure and temperature of the steam and the variation in measurement parameters with steam type. The main types of steam include wet steam, saturated steam and superheated steam.

Steam is typically measured in process plants and used to generate electricity. Vortex and differential pressure (DP) flowmeters are the primary flowmeters used to measure steam. Electromagnetic flowmeters cannot measure steam flow, and Coriolis and ultrasonic flowmeters are just starting to be used for this purpose. In addition to being able to withstand high process temperatures and pressures, electromagnetic flow meters also have a wide adjustable range. This allows them to measure steam flow at different speeds. In processes and power plants, steam from boilers is often measured.

Multivariable electromagnetic flowmeters are becoming increasingly popular among suppliers and end users. Mingyu Instrument Company introduced a multi-variable electromagnetic flowmeter in 2000. The instrumentation includes an RTD temperature sensor and a pressure sensor with a vortex flowmeter. By using information from these sensors, flow meters can determine volumetric flow, temperature, pressure, fluid density and mass flow. Multivariable electromagnetic flowmeters and multivariable DP flowmeters are also available, while multivariable ultrasonic flowmeters are popular in district heating applications.

Although multivariable flow meters are more expensive than single variable flow meters, they enable the user to obtain more information about the process than single variable volume meters. This additional information can improve efficiency and more than make up for the additional cost of a multivariable flow meter. Multivariable electromagnetic flowmeters also have the ability to measure mass flow, which makes them attractive, especially for steam and gas flow measurements.

A variety of installation types are available

Electromagnetic flowmeters are available in flange, disc and plug-in types. Flange and wafer (inline) styles offer greater accuracy than insert gauges, but are not practical in large line sizes. Vortex meters are available in the 16" range z-tall. The "point" in terms of vortex flow meter size is 1" to 4". Whether the user chooses an inline or insert meter depends on a number of considerations. These include the required accuracy and repeatability properties, pipe size, fluid type, and required supplier or distributor

Although flange-type vortex flowmeters are slightly more expensive than wafer-type flowmeters, they are safer than wafer-type flowmeters. , less chance of leakage. Longer bolts used to secure wafer-based instruments have a tendency to expand, creating the potential for leakage, which may result in fugitive emissions and loss of product to the wafer. Downsizing companies may require fewer skilled engineering personnel to perform these installations than flanged vortex flowmeters.

Insertion-type electromagnetic flow meters provide a viable option for companies that want to measure flow in large pipes, especially those with an inner diameter greater than 12 inches. Common accuracy levels for insertion electromagnetic flowmeters are 1% range for liquids and 1.5% for steam and gases. Although thermal flow meters are better suited for gas measurements than liquid measurements, gases and vapors are more difficult to measure than liquids for most flow meter types.

Insert meters are sometimes used to measure flow in pipes that cannot be shut off. Because plug-in instruments are hot-swappable, instruments can be replaced or components replaced without shutting down the line. Inline meters do not have this advantage unless a bypass line is installed, and even then the line must be closed to install the bypass line. This allows insertion eddy current meters to provide greater flexibility than inline meters.

One reason insertion vortex flow meters cannot achieve the same accuracy as some in-line flow meters is that they measure at a single point within the pipe. Some inline meters, such as multipath ultrasonic meters, take multiple measurements and create a calculated average to determine flow. A vortex flow meter is inserted to take point measurements and then the flow rate is calculated for the entire pipe based on the flow profile consideration. The formula used to make this calculation is based on extensive testing and can be improved with time and experience.

Insertion electromagnetic flowmeters compete with insertion magnetometers and insertion electromagnetic flowmeters as well as averaging pitot tubes. They are superior to insertion magnetic flowmeters, which cannot measure the flow of gas or steam. Although insertion magnetic flowmeters are very effective in clean fluids, their rotors and bearings can be damaged by impurities in the flow. Vortex meters can handle fluids containing impurities as long as they do not move the bluff body.

Averaging pitot tubes are commonly used to measure air and flue gas flow rates. While a single-point pitot tube can also measure flow at a point, a pitot tube averages the flow at multiple points and makes a total flow measurement based on these multiple measurements. While multiple flow measurements in a pipe usually produce more accurate results than a single point measurement, the average pitot tube can become clogged with impurities in the flow.

Insertion vortex flow meters are usually placed in the center of the pipe, where the flow rate is the fastest. However, other positions are possible depending on the measurement configuration. Typically, insertion electromagnetic flow meters are adjustable, allowing them to be used with different sized pipes, and they have lower installation costs than insertion DP flow meters.

Interestingly, the top three suppliers of electromagnetic flowmeters, Yokogawa, Emerson Rosemount and Endress+Hauser, do not produce insertion electromagnetic flowmeters. Instead, they left this market to a few* smaller vendors. Examples of suppliers of insertion electromagnetic flow meters include VorTek Instruments, Spirax Sarco, Oval Corporation, and Nice Instrumentation.

Spirax Sarco launched its inline electromagnetic flowmeter in 1986 andIn 1991, the insertion vortex flowmeter was launched. At the time, the company was known as EMCO Flow Systems. EMCO is headquartered in Longmont, Colorado, and was acquired by Spirax Sarco of the United Kingdom in 2005.

VorTek Instruments was founded in 1995 and specializes in electromagnetic flow meters, including wafers, flanges and inserts. The company also sells electromagnetic flow meters. In January 2013, Azbil acquired a majority stake in VorTek Instruments. Azbil is a Japanese company formerly known as Yamatake Corporation. Since the acquisition, Azbil VorTek has continued to market its vortex and electromagnetic flowmeters and has developed a line of ultrasonic flowmeters.

How the electromagnetic flowmeter market is booming

Since its introduction in 1969, electromagnetic flowmeters have had their ups and downs. Vibration issues temporarily cause problems, producing false readings. Vendors have addressed this problem by developing advanced software that can distinguish between true eddies and extraneous disturbances. Measuring very low flow rates remains a problem for electromagnetic flowmeters because the flow rate must be fast enough to create vortex currents. Reducer electromagnetic flowmeters are introduced to produce stronger eddy current signals, especially at low flow rates.

For many years, electromagnetic flowmeters have lacked industry recognition. Industry certifications, especially for custody transfer operations, have greatly aided the growth of the DP, turbine, ultrasonic, magnetic and Coriolis flowmeter market. In 2007, a committee of the American Petroleum Institute (API) approved a draft standard for the use of electromagnetic flow meters for custody transfer applications. Although the draft standard had little impact on the market initially, it was revisited in 2010. It has now been reformulated more specifically as a gas flow measurement standard. While the future of this draft standard has not yet been determined, it is likely to have a positive impact on the market.

The Future of Electromagnetic Flowmeters

Research frontiers for electromagnetic flowmeters include improving accuracy and continuing to investigate the suitability of electromagnetic flowmeters for steam and gas applications. The multivariable electromagnetic flowmeter market is expected to continue growing. It will be interesting to see if the "three*" suppliers of vortex flowmeters decide to manufacture insertion electromagnetic flowmeters.