Barbell Horn Ultrasonic Technology
INTRODUCTION TO BARBELL HORN ULTRASONIC TECHNOLOGY
Industrial Sonomechanics , LLC (ISM), specializes in high-capacity commercial-scale ultrasonic homogenizers adapted to many industrial processes. In addition, ISM provides laboratory and bench-scale ultrasonic systems which can be used to study processes before they are scaled up or for semi-industrial scale production. As described below, several unique features of ISM’s patented Barbell Horn Ultrasonic Technology (BHUT) make it possible to directly transfer what can be accomplished in the laboratory to the plant floor, guaranteeing reproducible and predictable results at any scale.
Advantages of High Ultrasonic Amplitudes
Liquids exposed to high-intensity ultrasound undergo ultrasonic cavitation, which produces violently and asymmetrically imploding bubbles and causes micro-jets that create extreme mechanical shear forces. These forces are responsible for the well-known ability of ultrasound to tremendously facilitate many physical and chemical processes. Ultrasonic amplitudes on the order of 100 microns peak-to-peak (below, "microns") are commonly necessary in order to take full advantage of this effect. At low amplitudes (below about 50 microns), the intensity of ultrasonic cavitation is insufficient for many processes. For example, such processes as nano-crystallization, nano-emulsification, deagglomeration, extraction, as well as many others, are inefficient or do not occur at low amplitudes. In order to produce sufficient cavitation intensity, ultrasonic transducers (sometimes also called "converters") are equipped with high-gain acoustic horns (sometimes also called "sonotrodes" or, together with transducers, "probes"), which amplify the vibration amplitudes generated by the transducers and deliver the ultrasonic energy to working liquids.
Converging Horns - Main Limitation of Conventional Ultrasonic Technology
Conventional ultrasonic systems utilize acoustic horns that converge in the output direction and are restricted to having small output tip diameters in order to provide high amplitudes. Converging horns are excellent for studying processes on a laboratory scale, but they make it impossible to transfer the processes to an industrial scale. Process scale-up requires switching to horns with larger output tip diameters, able to output the ultrasonic energy into larger volumes of working liquids while still maintaining high amplitudes. If, however, the output tip diameter of a conventional horn is increased, its maximum vibration amplitude necessarily becomes significantly lower.
For example, ultrasonic amplitudes on the order of 100 microns can only be reached by conventional horns when their output tip diameters do not exceed about 25 mm (laboratory scale). Conventional horns with output tip diameters of 50 mm and above (industrial scale) operate at maximum amplitude of about 25 microns, irrespective of the specified system power. Conventional ultrasonic technology, therefore, does not permit to directly transfer high-amplitude ultrasonic processes from laboratory to industrial scale, which is why numerous successful laboratory studies have never been implemented in industrial production.
Barbell Horns - Scalable High-Amplitude Ultrasound
Barbell horns, developed by ISM, are able to amplify ultrasonic amplitudes while retaining large output diameters. Barbell horns utilized in our industrial 2400 W systems can have output diameters as large as 75 mm and produce extremely high ultrasonic amplitudes, exceeding 100 microns. Our 1200 W systems designed for process optimization and medium-scale production feature Barbell horns with output tip diameters up to 35 mm, which are also able to output ultrasonic amplitudes exceeding 100 microns. Thus, Barbell horns make it possible to directly reproduce any laboratory or bench-scale process optimization study in a commercial production environment. Since the scale-up is accomplished without changing any of the optimized parameters, including the amplitude, the process is guaranteed to generate the same reproducible results on the plant floor as it does in the laboratory.
Because system productivity depends on the size of the active cavitation zone created under a horn, which is proportional to the area of the horn's output surface, productivity rates in Barbell horn-based systems can be orders of magnitude higher than those achieved with conventional ultrasonic devices.
Different Types of Available Babell Horns - Shapes Adapted to Each Application
Barbell horns are available in different shapes and sizes. Besides Full-wave Barbell horns of the type shown above, specialized Half-wave Barbell horns and Open Barbell horns (Full and Half-wave) are available. These recently introduced horns are smaller and lighter that Full-wave Barbell horns and have shapes that, when incorporated into appropriately designed reactor chambers, ensure that no working liquid bypasses the active cavitation zone. These horns are, therefore, preferred for the tasks involving high-intensity flow-through ultrasonic processing, such as deagglomeration of solid particles, nanoemulsification and the production micronized waxes, where uniform exposure to ultrasound and the resulting narrow particle size distributions are essential. Different types of available ultrasonic horns are described here.