Advanced functionality in the latest level measurement devices enables them to meet the demands of even the most challenging chemical industry applications. Increasing level measurement accuracy and reliability helps to enhance plant and worker safety while maximizing production efficiency, helping organizations to make substantial cost savings.
Chemical processing plants tend to be harsh environments that place arduous demands on level measurement instrumentation. Production processes can involve materials that are toxic, corrosive, flammable or explosive, usually with extreme temperature and pressure ranges, and challenging media characteristics that can affect measurement accuracy and reliability. To support process engineers, Emerson has produced a comprehensive white paper entitled ‘Smarter, safer chemical operations: How advanced level measurement devices solve chemical production challenges’, that focuses on a number of typical chemical industry applications and explains how Rosemount™ advanced level measurement devices provide the ideal solution.
Level measurement applications in chemical process plants can present a broad array of challenges, which can be met by a number of different technologies. These include electronic devices such as guided wave radar (GWR) transmitters, non-contacting radar (NCR) transmitters and vibrating fork switches, which offer increased diagnostics and reliability, plus lower lifecycle costs.
Reactors and mixer vessels
The paper outlines the level measurement challenges faced in reactors and mixer vessels, and explains how Rosemount 5408 NCR Level Transmitters are providing a successful solution at the Perstorp Specialty Chemicals plant in Sweden. The plant’s reactors and mixer vessels contain central shaft agitators, running at 30-80 revolutions per minute, at multiple levels. This makes the process material surface extremely turbulent and therefore difficult to accurately measure. Some of the vessels also contain a thick layer of dense foam and can be prone to condensation.
The white paper states: “The high sensitivity and unique software features of the Rosemount 5408 enable it to handle the foamy environment, while advanced signal processing allows the device to accurately measure the process material surface despite the extreme turbulence within the tanks. In addition, the device’s process seal antenna is a good solution for dealing with the heavy condensation that can be present in the tanks.”
The company now has accurate and reliable continuous level measurement in these vessels, despite the challenging process conditions. This has resulted in fewer lost batches and reduced downtime, maintenance requirements and costs.
When vessels or tanks are located in remote areas of the plant, wireless networks can support automated level measurement solutions without the need to install costly new cabling and disrupt operations. The white paper describes the example of a storage terminal in Lyon, France, operated by a global chemical distribution company.
The terminal operator needed to achieve a high degree of level measurement accuracy to efficiently manage stock levels in its tanks, but problems with corrosion on the housing and copper wires of its transmitters was affecting their accuracy and reliability. The distance between the tanks and environmental barriers prevented all the tanks from being monitored with wired solutions. The company therefore opted for a wireless solution from Emerson using Rosemount 3308 Wireless Level Transmitters, Rosemount 2160 Wireless Vibrating Fork Level Switches and two wireless gateways.
The white paper states: “With wireless communication, the company is now able to manage each quantity of product in its tanks with better accuracy. Retrofitting the devices onto the tanks was quick and easy, and their remote diagnostics capability increases reliability and reduces downtime.”
Solids level measurement
Measuring the level of solids can often be challenging because of the variables that can affect measurement accuracy and reliability. These variables include uneven surfaces and rapidly changing levels, material accumulation and clogging, the dielectric constant and bulk density of materials, the amount of dust that is created during fill cycles, the presence of condensation and noise, and electrostatic discharges. Among the organizations typically affected by challenges such as these are producers of lime, limestone, and clay products.
The white paper describes some of the applications that were presenting level measurement challenges at a large lime processing plant in the US, including a 4ft hydrated lime surge bin, two 112ft coal silos, and hydrated lime storage silos. In all these applications, Rosemount instruments were selected to replace other technologies or devices that were not providing the required accuracy and reliability.
The white paper reveals that: “By having more accurate and reliable solids level measurements, the plant is not only able to more efficiently schedule the delivery of raw materials such as coal, but can also track the movement of lime products throughout the plant. Reducing maintenance requirements and eliminating downtime due to problematic devices has increased personnel safety and increased operational efficiency.”
In overfill prevention systems (OPS), modern electronic technologies that offer increased diagnostics and reliability include vibrating fork switches for point level measurement, and GWR and NCR devices for continuous measurements. The white paper explains that NCR devices featuring 2-in-1 technology can be used simultaneously in both a basic process control system (BPCS) and an OPS. This technology is used in the Rosemount 5900S 2-in-1 radar level gauge from Emerson, which consists of two galvanically separated and independent gauges within the same housing using a single antenna. This solution allows for cost-efficient safety upgrades of existing tanks by replacing a single BPCS or OPS sensor with two continuous level measurements, with little or no tank modifications, as only a single opening is required.
In addition to these applications, the white paper explains how advanced Rosemount devices are enabling end users to achieve significant benefits through the automated monitoring of containment areas around tanks, and through functionality that allows proof-testing of devices and safety loops to be performed remotely, thereby minimizing tank downtime and increasing site and worker safety.
For additional information on Emerson’s level measurement products, visit www.Emerson.com/RosemountLevel.