Ultracompact Coriolis Mass Flowmeters Provide Accessibility to Coriolis Technology with Lower Capital Cost

Summary

Coriolis mass flowmeters are often used in chemical and other industrial applications requiring high accuracy and reliability. In addition to the primary mass flow reading, they can also provide secondary density and temperature measurements to host systems. Coriolis mass flowmeters consist of a sensor and a transmitter, with the latter storing and sending process and diagnostic data to host systems via various types of digital communication protocols. Typical hosts include a distributed control system (DCS), an asset management system, a laboratory information system and others.
 
Coriolis flowmeters are ideally suited for process plants tasked with meeting environmental, social and governance targets because they support efforts to reduce energy intensity, minimize emissions, improve safety and report these datapoints. This information is vital for providing these and other benefits, but end user needs must be considered.
 

End user pain points

Some Coriolis meters are quite large and heavy, making installation and maintenance difficult. In the past, these types of meters have been quite expensive as compared to other flow measurement technologies, and selection and configuration has often been quite complex.
 
When a process plant instrumentation management team needs to use many suppliers to provide Coriolis flowmeters for their entire range of applications, costs increase and personnel productivity decreases. Regardless of plants’ supplier networks, some users may require education and training on the benefits provided by mass flow measurement, particularly concerning use of all the extended data available from these devices. This issue is exacerbated when many different suppliers are used, as each tends to have their own product idiosyncrasies. To address these and similar issues, a high level of supplier expertise is often required, both for initial product selection and ongoing support.
 
While a wide range of products is essential if a company plans to rely on a single supplier, capital cost can be just as important. Not every application requires the full range of Coriolis flowmeter capabilities, and using the most complex and expensive meter for a simple application is often cost prohibitive. End users therefore typically prefer a supplier offering tiered capabilities, with options available to provide features only when needed.
 
Two-wire meters are typically the preferred choice in situations where running an extra pair of wires to power the meter is particularly expensive, but end users often still need a wide range of features and diagnostic data in two-wire meters, so suppliers must offer these meters with limited compromises regarding capabilities.
 

Addressing the issues

Process plants prefer to rely on one supplier with extensive domain expertise for their entire range of Coriolis flowmeter needs, from the largest to the smallest, with options for adding more capabilities, but also simpler products for those applications with capital cost constraints.
 
Simplification also provides ease of use in applications where only a basic mass flow, and possibly a density reading, are required. Simplification should extend further, with streamlined model codes and quick sizing guidance to provide easy product selection and configuration.
 
When a single supplier can be relied upon to provide Coriolis mass flowmeters for a plant’s entire range of applications, personnel productivity increases because staff only need to be trained on one line of products. To reach this goal, the supplier must provide effective solutions across a wide range of applications.
 
Many volumetric flowmeters are installed with a single 4-20mA output connected to the control system, and simple two-wire Coriolis mass flowmeters provide a similar level of simplicity, with lower capital costs than four-wire mass flowmeters.

 
From basic to complex

For more complex applications, mass flowmeters deliver maximum value when connected to host systems via a digital data link of some type. For example, when a product from the Emerson Micro Motion G-Series family of mass flowmeters is used with the Emerson Micro Motion 4700 Coriolis Transmitter (Figure 1), wired options are:

• Channel A includes 4-20mA HART for two-way communications, a frequency output and a discrete output.
• Channel B includes a 4-20mA, frequency and discrete output, and a discrete input.
• Channel C provides two-way digital communication via Modbus RS-485.

• Mass flow measurement
• Density measurement
• Temperature measurement
• Smart Meter Verification—checks the health and integrity of the meter's tubes, electronics and calibration without interrupting the process
• Zero verification—quickly diagnoses the meter to determine if re-zeroing is recommended, and if process conditions are stable and optimal for zeroing
• Multiphase detection—proactively identifies the presence and severity of multiphase process conditions, where gas is entrained with fluid and can introduce measurement errors
• Time-stamped digital audit trails and reports for optimized agency compliance

Primary mass flow measurement data is typically used by the DCS for closed-loop control, where this measured value is the process variable in a PID algorithm that maintains an operator-defined mass flow rate target setpoint. The algorithm’s output is typically sent to a final control element to regulate flow, such as a control valve, or a variable speed drive connected to a pump.
 
The other secondary data can be used by the DCS and other host systems to improve many aspects of plant operation, including real-time control, calibration and maintenance.
 

Reducing weight and size

Although Coriolis meters don’t require upstream or downstream straight pipe runs as with many other flow measurement technologies, some models have a larger footprint than volumetric devices, limiting their use in confined spaces. Another issue with some traditional Coriolis designs is a higher weight than volumetric counterparts, which can be a problem in certain applications, such as portable process skids.
 
Overall, volumetric flow measurement devices are typically smaller and lighter than mass flowmeters. Therefore, one challenge is reducing the size and weight of Coriolis flowmeters, while maintaining high accuracy and reliability.
 
Newer designs, such as the Emerson Micro Motion G-Series Coriolis Flow and Density Meters, address the size issue, for example with a face-to-face dimension for a 1-inch line size model of less than 12 inches (Figure 2). The smaller size of these flowmeters comes with lower weight, an important factor for transport and installation, and for overall safety when handling the meters.

Meeting requirements

In addition to the aforementioned attributes, there are other requirements instrument specifiers should consider. Leading Coriolis flowmeters comply with the Pressure Equipment Directive, include SIL2 and SIL3 safety certification, and meet NAMUR NE 132 guidelines. Meters for use in sterile applications must also meet 3A or EHEDG certification for the food and beverage, life sciences and other hygienic industries.
 
A wide variety of lines sizes should be available from ¼-inch (DN6) to 3-inch (DN80), with product selection simplified using streamlined configuration and sizing guidance. Direct laser-etch instrument tagging (Figure 3) is preferred to adhesive labels or spot-welded tags because it provides durability in even the harshest conditions. 

 

Typical applications

The G-series Coriolis flowmeter is well suited to these chemical industry mass flow measurement applications:

• Transfers between tank farms and process units requiring mass flow only with moderate turndown.
• Utilities for instrument air, nitrogen and demineralized water with high accuracy, as well as boiler fuel feed of fuel oil or natural gas.
• Noncritical chemical blending and mixing operations requiring both flow and density indications.
• Inhibitor feed to furnace scrambler, as well as decoking air to the furnace, with data from the meter used to improve combustion efficiency.

Life science and food and beverage OEM applications include:

• Water-based sauces and beverages
• Process skid systems
• Filling systems
• Utilities
• Clean-in-Place systems

For all industries, replacement of traditional technologies, including:

• Turbine flowmeters used in truck loading operations, where increased reliability is required, along with minimal or no maintenance as spares are typically not available.
• Turbine flowmeters used in natural gas systems.
• Rotary meters for feedwater applications.
• Thermal mass flowmeters used for compressed air measurement.

Conclusion

Coriolis mass flowmeters have long been used when high accuracy, long-term reliability and installation flexibility were required, but in some instances their relatively high capital cost and large size as compared to traditional technologies have limited use. Newer designs address these and other issues, opening up additional areas and applications where they can be applied to advantage.
 
A trusted supplier offering a wide range of Coriolis mass flowmeters, along with a full range of flow measurement technologies, can help users evaluate their new and existing applications so they can select the best option.
 
_{All figures courtesy of Emerson}