Level measurement plays a critical role in ensuring the safety and efficiency of chemical processes, including liquid extraction, vapor/liquid separation, and mixing and blending. Some common application challenges include:
Foam is a dynamic mixture of gas and liquid which can present difficulties with traditional level devices; that is, some of the most widely accepted technologies in the market.
The foam thickness, density, bubble size and effective dielectric constant (most of which continuously vary during a process) can impact the level measurement.
Depending on the level transmitter or switch technology, as well as the properties of the foam, the instrument may be able to detect the foam, it may ignore the foam and only measure the liquid level, or it may lose the signal altogether in the foam layer. There are many reasons why foam can be present in a tank. This includes the product being manufactured, the use of agitators / mixing blades, or if there is air/gas introduced. Regardless of the reason, care must be taken in choosing level instrumentation to prevent unnecessary errors or loss of measurement.
There are a wide range of chemicals produced including acids, buffers, ammonia, chlorine and solvents. Some chemicals are corrosive enough to destroy contacting technologies or can crystallize and coat probes to render them ineffective. There are options to coat the probe to assist in corrosive environments along with a variety of materials of construction. However, there may still be a preference to move to a non-contacting technology.
Although GWR has many advantages, a contacting technology will always be subject to viscous or sticky process fluids that can coat the probe. Advanced diagnostics should be present in the device to detect and monitor build-up on the probe. This allows the user to plan cleaning processes before a measurement problem occurs. There are also options to coat the probe to reduce material buildup or assist in corrosive environments (flushing ports can also be provided). However, there may still be a preference to move to a non-contacting technology for applications with coating, corrosion or installation concerns.
The best practices long established in the Oil & Gas industry through standards such as API 2350 may be applied to the Chemical Processing industry. GWR has been a reliable technology for decades in preventing tank overfill of hazardous liquids; including overfill capable probes to allow direct measurement of liquid level from the bottom of the probe up to the process connection without relying on algorithms. In Chemical, both liquid overfills and foam-overs are possible depending on the process.
At Magnetrol, because of our long history of leading the level measurement industry, we can provide our customers the depth of application and technology expertise needed to mitigate foam issues, along with other application challenges the chemical and other processing industries face. We offer a full range of contact and non-contact level instrumentation, including the industry’s most reliable GWR. To learn more, download our new "Foam in the field" white paper or visit us at magnetrol.com.