Bitumen Equipment. Emulsion are made by machines and equipment with different designs and operation principles. Below is a classification of bitumen emulsion machines.
There are three methods of emulsification currently in use:
- mechanical emulsification
- acoustic emulsification
- physical (spontaneous) emulsification.
Accordingly, there are three types of machinery.
The first type of equipment emulsifies fluids by pushing them through a narrow gap between a stator and a rapidly rotating rotor, under the influence of centrifugal forces. In some machines, fluids are pushed through a narrow conical passage between two fixed parts using a plunger system. The first type of machines also includes mixers where liquids are emulsified by their turbulent motion.
The principle of operation of the second type of equipment is the use of sonic and ultrasonic waves created by a vibration device. The manner in which acoustic waves act in the process of dispersion is explained differently by various researchers. Some suggest that the ultrasonic wave, passing over a particle, create varying accelerations acting on different points of the particle, thus breaking it. Others point at the forces, created by the ultrasonic waves between the rapidly moving emulsifier solution and the suspended particles of the binder. Most researchers explain the effects of ultrasonic waves by cavitation. Cavitation is the emergence of cavities in the liquid, which then collapse. The process of collapse results in high pressure, breaking particles. Hydrodynamic and electromechanical devices generate ultrasonic waves in bitumen emulsification equipment.
The physical/chemical (spontaneous) emulsification is based on using increased amount of emulsifier which sharply reduces the interfacial tension on the boundary between emulsified liquids. Emulsion may form spontaneously or with the use of very simple equipment.
Mechanical dispersion machines are the most commonly used. This type includes machines which operate continuously or in batches. The former are referred to as homogenizers, dispersers and colloid mills. Some of the names are indicative of the design (e.g. colloid mill), some refer to the process (disperser). Of the listed names, the one which describes the process of emulsification is “homogenizer”. The emulsification process, regardless of its technology, includes dispersion, that is, pulverization of the suspended phase, and homogenization, i.e. making a uniform mix, the end result of the process. When an emulsion machine is called a homogenizer, this means that its product is dispersed homogeneous material.
At this time, homogenizer means a machine, in which prepared coarse emulsion is mixed to a finer state.