Efficient Biorefineries via Ultrasonic Process Intensification
Ultrasonication is a process intensifying technique, which is implemented into various processes in biorefineries. Typical processes that benefit significantly from ultrasonic treatment are extraction, slow heterogeneous reactions as well as other applications that involve intense mixing, homogeniaztion and dispersing. Ultrasonication accelerates processes and reactions and makes them more efficient. Results of ultrasonically-promoted processes are higher yields/outputs and higher conversion rates.
What are Bio-Refineries?
A biorefinery is a production facility that integrates biomass conversion processes and processing equipment to produce fuels, energy and other beneficial products such as chemicals from the biomass raw material. Typical biomass processed in biorefineries include raw materials such as agricultural waste and by-products, which is up-cycled into various value-added, bio-based products, e.g., food, feed, chemicals, bioenergy (biofuels, power and/or heat). The production processes of a biorefinery are intended to be sustainable and environmental-friendly. Similar to conventional refineries, biorefineries can provide multiple chemicals by fractioning an initial raw material (biomass) into multiple intermediates (carbohydrates, proteins, triglycerides) that can be further converted into value-added products. A key characteristic of biorefineries is valorization and recycling/upcycling of waste such as agricultural, urban, and industrial waste by the means of converting useless biomass into valuable materials.
Ultrasonically Intensified Biorefineries
By the integration of ultrasonication, many processes such as extraction, digestion, disintegration, transesterification amongst many others can be run significantly more efficient. Ultrasonic process intensification in a biorefinery aims mainly to improve yields, to make processes more time- and energy-efficient and to enhance the purity and quality of the final product. Ultrasonication can contribute to various biorefinery processes.
How Does Sonication Work? – The Working Principle of Ultrasound
For high-performance ultrasonic processing, high-intensity, low-frequency ultrasound is generated by an ultrasound generator and transmitted via an ultrasonic probe (sonotrode into a liquid. High-power ultrasound is considered ultrasound in the range of 16-30kHz. The ultrasound probe expands and contracts e.g., at 20kHz, thereby transmitting respectively 20,000 vibrations per second into the medium. When the ultrasonic waves travel through the liquid, alternating high-pressure (compression) / low-pressure (rarefaction or expansion) cycles create minute vacuum bubbles or cavities, which grow over several pressure cycles. During the compression phase of the liquid and bubbles, the pressure is positive, while the rarefaction phase produces a vacuum (negative pressure.) During the compression-expansion cycles, the cavities in the liquid grow until they reach a size, at which they cannot absorb more energy. At this point, they implode violently. The implosion of those cavities results in various highly energetic effects, which are known as the phenomenon of acoustic / ultrasonic cavitation. Acoustic cavitation is characterized by manifold highly energetic effects, which impact liquids, solid/liquid systems as well as gas/liquid systems. The energy-dense zone or cavitational zone is known as so-called hot-spot zone, which is most energy-dense in the close vicinity of the ultrasonic probe and declines with increasing distance from the sonotrode. The picture left shows intense cavitation at an 1kW ultrasonic probe in water. The main characteristics of ultrasonic cavitation include locally occurring very high temperatures and pressures and respective differentials, turbulences, and liquid streaming. During the implosion of ultrasonic cavities in ultrasonic hot-spots, temperatures of up to 5000 Kelvin, pressures of up to 200 atmospheres and liquid jets with up to 1000km/h can be measured. These outstanding energy-intense conditions contribute to sonomechanical and sonochemical effects that intensify biomass and chemical systems in various ways.
The main impact of ultarsonication on biomass result from the following effects:
- High-shear: Ultrasonic high-shear forces disrupt liquids and liquid-solid systems causing intense agitation, homogenization and mass transfer.
- Impact: Liquid jets and streaming generated by ultrasonic cavitation accelerate solids in liquids, which leads subsequently to interparticluar collision. When particles collide at very high speeds, they erode, shatter and get milled and dispersed finely, often down to nano-size. For biological matter such as plant tissue and bio-waste, the high velocity liquid jets and alternating pressure cycles disrupt the cell walls and release the intracellular material. This results in highly efficient extraction of bioactive compounds and the homogeneous mixing of biomass.
- Agitation: Ultrasonication causes intense turbulences, shear forces and micro-movement in the liquid or slurry. Thereby, sonication always intensifies mass transfer and accelerates thereby reactions and processes.
High-performance ultrasonics is a process intensifying technique applied to multiple industries. Ultrasonication is used to process liquids and slurries in order to mix and homogenise, promote mass transfer, extract compounds and/or to initiate chemical reactions.
Common applications of ultrasonication in biorefineries are:
- bioethanol production
- extraction of valuable compounds from biomass (e.g. proteins, pectins, starches etc.)
- biodiesel synthesis from spent vegetable oils and animal fats
- biodiesel from algae oil
- lignocellulose treatment
- starch modification
High-Performance Ultrasonic Processors for Biorefineries
Hielscher Ultrasonic manufactures and distributes high-shear ultrasonic mixers for high-performance application such as homogenisation, mixing, cell disruption, disintegration, extraction, dispersion, degasification and the initiation of chemical reactions. Ultrasonic reactors are implemented in biorefineries worldwide in order to increase efficiency, yields and conversion rate of various processes.
High-performance ultrasonic equipment for biorefinery processes is readily available for bench-top, pilot and industrial installation. Since ultrasonic applications such as extraction, disintegration, dissolving, improvement of mass transfer, homogenization and deaeration are already established processes, the transition from first trials, optimisation to your specific process requirements and installation of a fully-industrial ultrasonic separation and/or leaching system is quick and simple.
Hielscher Ultrasonics supplies high-performance ultrasonicators at any size and capacity. With the UIP16000 (16kW), Hielscher manufactures the most powerful ultrasonic processor worldwide. The UIP16000 as well as all other industrial ultrasonic systems can be easily clusters to the required processing capacity. All Hielscher ultrasonicators are built for 24/7 operation under full load and in demanding environments.
Ultrasonic Probes and Sono-Reactors for Any Volume
Hielscher Ultrasonics product range covers the full spectrum of ultrasonic processors from compact lab ultrasonicators over bench-top and pilot systems to fully-industrial ultrasonic processors with the capacity to process truckloads per hour. The full product range allows us to offer you the most suitable ultrasonic equipment for your application, process capacity and production targets.
Precisely Controllable Amplitudes for Optimum Results
All Hielscher ultrasonic processors are precisely controllable and thereby reliable work horses in R&D and production. The amplitude is one of the crucial process parameters that influence the efficiency and effectiveness of sonochemically and sonomechanically induced reactions. All Hielscher Ultrasonics’ processors allow for the precise setting of the amplitude. Sonotrodes and booster horns are accessories that allow to modify the amplitude in an even wider range. Hielscher’s industrial ultrasonic processors can deliver very high amplitudes and deliver the required ultrasonic intensity for demanding applications. Amplitudes of up to 200µm can be easily continuously run in 24/7 operation.
Precise amplitude settings and the permanent monitoring of the ultrasonic process parameters via smart software give you the possibility to process biomass under the most effective ultrasonic conditions. Optimal sonication for most efficient biomass upcycling!
The robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments. This makes Hielscher’s ultrasonic equipment a reliable work tool that fulfils your biorefining process requirements.
Highest Quality – Designed and Manufactured in Germany
As a family-owned and family-run business, Hielscher prioritizes highest quality standards for its ultrasonic processors. All ultrasonicators are designed, manufactured and thoroughly tested in our headquarter in Teltow near Berlin, Germany. Robustness and reliability of Hielscher’s ultrasonic equipment make it a work horse in your production. 24/7 operation under full load and in demanding environments is a natural characteristic of Hielscher’s high-performance ultrasonic probes and reactors. Our skilled team is ready to assist you with process knowledge, training and support.
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:
|Batch Volume||Flow Rate||Recommended Devices|
|1 to 500mL||10 to 200mL/min||UP100H|
|10 to 2000mL||20 to 400mL/min||UP200Ht, UP400St|
|0.1 to 20L||0.2 to 4L/min||UIP2000hdT|
|10 to 100L||2 to 10L/min||UIP4000hdT|
|n.a.||10 to 100L/min||UIP16000|
|n.a.||larger||cluster of UIP16000|
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Literature / References
- García, A., González Alriols, M., Wukovits, W. et al. (2014): Assessment of biorefinery process intensification by ultrasound technology. Clean Techn Environ Policy 16, 1403–1410 (2014).
- Velmuruga, Rajendran; Muthukumar, Karuppan (2011): Utilization of sugarcane bagasse for bioethanol production: Sono-assisted acid hydrolysis approach. Bioresource Technology Vol. 102, Issue 14; 2011. 7119-7123.
- Petigny L., Périno-Issartier S., Wajsman J., Chemat F. (2013): Batch and Continuous Ultrasound Assisted Extraction of Boldo Leaves (Peumus boldus Mol.). International journal of Molecular Science 14, 2013. 5750-5764.