Electric Gas Boosters Promise Cleaner, Quieter, More Efficient Supercritical Fluid Extraction

Electric Gas Boosters Promise Cleaner, Quieter, More Efficient Supercritical Fluid Extraction

Supercritical Fluid Extraction (SFE) is used in industries such as food, cosmetics, nutraceutical/pharmaceuticals and cannabis for the extraction of essential oils, fragrances, herbs, spices, medicinals, and biomasses.

Perhaps the fastest growing market is cannabis for the extracting of CBD Oil to produce a variety of hash oils and compounds used in vaporizer pens, salves, edibles and elixirs.

The SFE process separates one component from another using a supercritical fluid as the extracting solvent.  Typically, this involves collecting a wanted product (i.e. essential oil) from an organic material like cannabis or removing an unwanted substance (i.e. caffeine) from a product like coffee using carbon dioxide (CO2) as the supercritical fluid.  At a critical combination of temperature and pressure, CO2 retains certain properties of a liquid and gas and can act as a solvent for extraction.  By manipulating temperature and pressure, the process can target key components for extraction.  In the process, the supercritical CO2 is recycled by drawing it off in gas form, and returned to liquid by recompressing and/or removing heat then it is re-used.

A key component in the SFE process is the gas booster, which pressurizes the CO2 or other gas to facilitate extraction and reuse.  Since OEMs do not manufacture gas boosters, they rely on suppliers to produce reliable, relatively “plug-in” units that can be easily integrated with their systems.

Unfortunately, traditional pneumatic and hydraulic gas boosters on the market have some inherent limitations that make them less suited to the clean environments where the extraction equipment will be used.

Unlike industrial plants, these extraction facilities do not usually have access to built-in facility compressed air systems.  To run an air-powered gas booster, therefore, requires purchasing and installing a compressor.  However, these systems are very loud and may even have to be installed outside the plant to meet OSHA requirements.

Hydraulic-powered gas boosters are slightly quieter than pneumatic, but there is also the potential for hydraulic fluid leaks or spills.  This makes them generally unsuitable for SFE processes, which must meet food-grade or higher levels of cleanliness.

Fortunately for OEMs, new electric gas boosters are now being manufactured that are cleaner, quieter and do not require compressed air.  Electric gas boosters also provide significant energy savings with more sophisticated self-diagnostics that ease use, allow greater process control, and improve reliability during the supercritical extraction process.

Clean, Quiet Electric Gas Boosters

There are often regulations governing the installation and operation of a compressed air system, particularly if powered by burning hydrocarbons, according to George Volk, Global Director of Sales and Business Development at Haskel, a division of Ingersoll Rand that manufactures gas/liquid transfer and pressurization technology.

While pneumatic gas boosters, driven by a compressed air system, may be acceptable for an industrial setting, the units were not designed for worksites employing the SFE process, which typically requires clean operation in a quiet setting.  “You may need to put the compressor outside and do your processing inside.” says Volk.

Pneumatic-driven gas boosters are also extremely loud during operation, and even louder if multiple units work in parallel in order to increase output, which can make complying with OSHA regulations related to sound levels in the facility more difficult.

Volk says that hydraulic gas boosters have similar issues when it comes to supporting the SFE process.

“With hydraulic gas boosters, there is always a concern that they could leak or spill hydraulic oil,” says Volk.  “This is a problem when there is a mandate for a certain level of cleanliness, which may include cleanrooms.  Hydraulic units are noisy too, though less so than pneumatic.”

The operation of typical air-operated and hydraulic-driven gas boosters can exceed the 85-dBA threshold, which can cause hearing loss.  OSHA requires employers to implement a hearing conservation program when noise exposure is at or above 85 decibels averaged over 8 working hours, or an 8-hour time-weighted average.

Instead of traditional pneumatic and hydraulic units, a far better choice for OEMs of SFE equipment is to opt for new electric gas boosters that simplify use for end users, while improving process control and reliability.

As an example, the advanced electric Q-Drive gas booster by Haskel simply use electricity and do not produce any emissions.  It is also much quieter (<77 dBA) during operation, while still offering up to

6,500 psi for high-pressure applications.  The direct electric drive is also much more energy efficient than either air or hydraulic drives.

“Electric units are ideal where high levels of cleanliness are required and they simplify the installation, along with hearing conservation programs,” says Volk.  “Their use can also streamline production, since workers can spend more time in the vicinity without worrying about exceeding the regulations or potential hearing loss.”

The electric units are also more energy efficient than both pneumatic and hydraulically driven boosters.

“Compared to pneumatic gas boosters, advanced electric units use one-third of the energy and offer flow rates 10 to 20 times higher,” says Volk.  “Compared to hydraulic boosters, the electric units also provide energy savings due to lower cooling requirements.

Although there are several electric-driven gas boosters on the market, even within the category there can be significant design differences.

Some of the early market entrants are designs that employ a gearbox to convert the rotary motion of the motor to reciprocating, which increases complexity and the amount of maintenance required.  More advanced units are built using a simplified linear actuator drive which enhances reliability and reduced the Mean Time Between Failure (MTBF).

Today’s more advanced electric units also include sophisticated remote and self-diagnostic capabilities.  Units such as the Q-Drive come with human machine interface (HMI) and touchpad control to allow operators to monitor and control pressure and temperature closely and easily change setpoints, which can help optimize the SFE process.  The system’s smart, virtual self-diagnostics and predictive maintenance capabilities also deliver automated maintenance reminders to ensure reliability and performance.

Given the inherent drawbacks of pneumatic and hydraulic gas boosters, Volk believes easier, cleaner, quieter operation of electric-powered units will have considerable appeal for supercritical extraction applications such as cannabis, perfume, food, and nutraceutical/pharmaceuticals, as well as many others.

“With the considerable R&D investment in these more advanced electric gas boosters, many of the shortcomings of pneumatic and hydraulic units have been resolved,” concludes Volk.  “This opens up new possibilities for OEMs that cater to the needs of businesses relying on supercritical fluid extraction.”

For more information, call (818) 843-4000 or visit www.haskel.com.


By Del Williams

Del Williams is a technical writer based in Torrance, California

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