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Considerations When Implementing Continuous and Point Level Controls for Biofuel Applications

The biofuel production process converts biomass resources into liquid fuels, such as ethanol, methanol and biodiesel, and gaseous fuels such as hydrogen and methane. The use of effective level measurement technology throughout these types of biofuel processing operations can greatly enhance your facility’s efficiency.

To handle complex measurement challenges like these, you need to implement accurate and reliable level instrumentation throughout your facility. Here are a few biofuel applications where you can take advantage of continuous and point level controls to improve the safety and productivity of your operations.

Ethanol is produced by converting the carbohydrates from biomass into sugar, which is then
converted into ethanol via a series of chemical reactions during the fermentation process. Ethanol and carbon dioxide are produced as the sugar is consumed by yeast or bacteria.

Level control of the fermentation tank can be especially challenging, because the level instrumentation selected must be able to tolerate agitation, aeration and the presence of froth or foam. Guided wave radar (GWR) or displacer transmitter technology are the most suitable continuous level control technologies for this application, while a top mounted displacer switch or external cage float switch can provide the point level control that this application requires.

Reactor Tank
Biodiesel and cellulosic ethanol production use reactors for chemical addition and mixing. In a continuous stirred-tank reactor, one or more fluid reagents are introduced into a tank reactor equipped with an impeller that stirs the reagents to ensure proper mixing.

In this application, plant operators face the challenge of providing reliable level monitoring and alarms for the reactor tank. GWR, displacer transmitter technology and thru-air radar (TAR) can provide a reliable continuous level control solution, while an external cage float switch is useful when point level control is required.

Reagent Tank
A reagent is a compound that is added to a system in order to bring about a chemical reaction. In biodiesel production, an alkali reagent is used in titration, a test used to determine how much catalyst is needed to achieve a reaction.

Reagents are stored in tanks equipped with level controls. Some of the most frequently used continuous level controls for this application include GWR and displacer transmitter technology. For point level control, an ultrasonic level switch is recommended.

Liquids are collected in sumps and pits during hydrolyzation, fermentation, distillation and glucose processing of biofuels. As the liquid level rises or falls in a sump, a level switch can actuate or deactuate a pump or activate an overfill alarm.

Level control devices, which include GWRs, TARs, displacer transmitters and ultrasonic level switches, can provide continuous measurement for this application, while top mounted displacers, displacer type liquid level switches and ultrasonic level switches work best for point level measurement in a sump.

Liquid Storage
A wide array of liquids are stored at biofuel plants including water, biodiesel, methanol, ethylene, catalysts and waste liquids. Level instruments monitor inventory levels and protect against overfills and underfills that cavitate pumps.

A TAR or GWR can provide a proven solution for this measurement challenge, by offering continuous level control. However, when point level control is needed, a float-actuated level switch is the best option.

Follow Our Renewable Energy Discussion
During the next few weeks, we will continue our discussion of level and flow instruments for the renewable energy industry. To learn more about this topic, please download the Magnetrol® Instruments for Renewable Energy Technology bulletin.