The BSP-1200 bench-scale ultrasonic liquid processor is designed for process optimization and medium-scale production. It outputs up to 1,200 W of acoustic power and operates at the frequency of approximately 20 kHz. The processor is supplied with a 1,200 W ultrasonic generator, a water-cooled piezoelectric transducer, a Barbell horn and an optional reactor chamber (flow cell).
The 1,200 W generator has rugged internal circuitry and ensures a continuous resonant frequency lock during operation. The LCD display can be used to change the settings for the ultrasonic amplitude, starting frequency and ramp-up or ramp-down parameters. Constant amplitude is provided, regardless of the power draw, which is automatically adjusted to compensate for variable loading conditions. The ultrasonic vibration amplitude level can be adjusted from 20 to 100 %. The generator passes strict CE test specifications for global applications.
The water-cooled piezoelectric transducer, SWCT-25-BSP, is sealed to the outside environment, which makes it immune to high-humidity conditions and suitable for the use with flammable materials, such as fuels and organic solvents. SWCT-20 is compatible with all ISM's ultrasonic horns and can be used in any liquid processing application of high-intensity ultrasound. In continuous duty operation, it is important to cool the transducer with flowing water or chiller fluid.
Several types of Barbell horns may be utilized with the processor. The HBH -type Barbell horns are commonly used in the flow-through processing mode, while the FBH-type Barbell horns are generally preferred for the batch processing mode. The horns have large output tip diameters (typically, 32 mm for HBH and 35 mm for FBH) and can deliver extremely high vibration amplitudes - up to 100 microns at 1 atm of pressure, calibrated by a high-precision fotonic sensor. These levels of vibration amplitudes are unprecedented: all competing bench-scale ultrasonic systems with similar horn tip diameters are restricted to amplitudes below about 40 microns, which severely limits their utility. The ability to reach high amplitudes at the bench scale gives investigators a wide range of ultrasonic exposure conditions to optimize even the most challenging ultrasonic processes. Once optimal conditions are established, the process can be transferred to a commercial scale utilizing the ISP-3000 industrial ultrasonic processor.
Productivity rates provided by the BSP-1200 processor are highly dependent on the nature of each process and range from about 1 L/h for challenging tasks (e.g., top-down nanocrystallization of active pharmaceutical compounds) to over 500 L/h for fast processes (e.g., oxidative waste-water purification, biodiesel production).
The Importance of High Ultrasonic Amplitudes
The ability of a bench or industrial-scale ultrasonic liquid processor to operate at high vibration amplitudes is essential. It has been shown that at the amplitudes below about 50 microns, many processes, such as nanocrystallization, nanoemulsification, deagglomeration, extraction, sterilization, dispersion as well as many others, are very inefficient. However, prior to the introduction of Industrial Sonomechanics' proprietary Barbell Horn Ultrasonic Technology (BHUT), high-amplitude bench and industrial-scale ultrasonic processors were unavailable.
High vibration amplitudes are relatively easy to produce in a laboratory setting - processors equipped with small-tip ultrasonic horns are readily available and widely used for lab-scale process optimization. A great deal of data has been published, showing that the required amplitude for many processes is between 60 and 100 microns at the frequency of 20 kHz. In order to implement a process in a semi-production environment, it is necessary to switch from a lab to a bench-scale ultrasonic system. The bench-scale system must incorporate a medium-diameter horn operating at the same high vibration amplitude and the same frequency as the lab system (direct scale-up). Based on BHUT, the BSP-1200 processor includes a medium-diameter Barbell horn (32 - 35 mm) capable of providing any vibration amplitude necessary to exactly replicate even the most demanding laboratory optimization results at the bench scale.
FLOW-THROUGH MODE CONFIGURATIONS
Recirculating and single-pass configurations are possible in the flow-through processing mode. The schematics shown above give a general overview, applicable to a wide variety of processes. The 1,200 W ultrasonic generator excites vibration in the water-cooled piezoelectric transducer. The vibration amplitude is then amplified by the HBH-type Barbell horn and delivered to the processed liquid, flowing through the reactor chamber. In the recirculating configuration (left), the material passes through the reactor chamber multiple times, which increases the exposure time. This configuration is recommended for challenging processes, such as top-down nanocrystallization (sonofragmentation) or the production of translucent nanoemulsions. The single-pass configuration is commonly used for faster processes, such as oxidative waste-water purification, the production of white nanoemulsions, degassing and biodiesel manufacturing. In this configuration, the processed formulation may be prepared in the premix tank (middle) or supplied by dosing pumps followed by a static mixer (right).
Reactor Chamber (Flow Cell)
The schematic of the reactor chamber utilized with the BSP-1200 processor, assembled with an HBH-type Barbell horn, is illustrated on the left. The internal volume of the assembly is about 80 ml. The penetration of the horn into the chamber is arranged such that the non-vibrating mounting flange on the horn is "sandwiched" between the body of the chamber and its lid through two rubber o-rings, ensuring a pressure-resistant seal. The processed liquid is supplied through the "inlet" and collected through the "outlet" 1/2" sanitary flange connections. Cold water or chiller fluid may be supplied to the reactor chamber's cooling jacket for temperature control.
BATCH MODE CONFIGURATION
Batch mode processing does not require the reactor chamber. In this mode, the processed liquid is contained in a batch container or a reservoir that may already be a part of the setup used in the process. Batch mode is commonly used for such processes as ultrasonic degassing of oils, paints, epoxies and other liquids. Several configurations are possible, corresponding to different types of Barbell horns, which are inserted directly into the processed liquid.
A schematic of the BSP-1200 ultrasonic processor in its FBH-type Barbell horn-based batch configuration is illustrated. The 1,200 W ultrasonic generator excites vibration in the water-cooled piezoelectric transducer. The vibration amplitude is then amplified by the FBH-type Barbell horn and delivered to the liquid in the batch container. The horn is immersed into the liquid approximately to its nodal point (to the depth of about 60 - 80 mm). Batch sizes of up to about 2 L can commonly be processed using this setup directly. Larger batch sizes (up to about 20 L) may require that the processed liquid be independently mixed. The liquid may be cooled by using a container equipped with a cooling jacket.