Lube-Tech
The barrier is made of materials that are transparent to microwave and does not absorb microwave itself. This is akin to viewing ports used on pressure vessels. The benefits have been spectacularly promising and include: 1. Heating from the bottom of the vessel results in the natural convection as the hot products rise and create a natural circulation in liquid products
2. Moving propellers and scraped surface mixing can be incorporated without arcing at the metal to metal gaps; or microwave leakage through the mixing shaft.
Improvement 2: The application of susceptors in the vessels. Susceptors are materials that absorb microwaves and emit infrared energy. They are used in a variety of applications. A simple example is sandwich wrappings with a coating of susceptor materials that heat up and toast sandwich buns bun when placed in a microwave oven. The use of susceptors in vessels for manufacturing grease requires special attention to the reflectivity and the susceptibility as well as the surface structure. Simply described, some mineral base oils like PAOs are mostly microwave transparent. This means when microwaves are applied, they could penetrate the oil with minimal loss of their magnetic strength and reach the walls of the vessel and bounce back. The reflected energy could return to the generator. If some dipolar materials such as azelaic acid are added to the PAO, then microwave absorption by the azelaic acid would heat quickly and heat the PAO through conduction. But, in order to ensure all products can be heated in a microwave vessel, a new patent pending process incorporates the use of susceptors in the vessel. In this case if the product is microwave transparent, then the waves are absorbed by the susceptor (instead of reflecting back). The susceptor reflects infrared heat energy to heat the material. The incorporation of susceptors in the vessels now allows microwave vessels to be used universally for processing products regardless of their polarity.
30 LUBE MAGAZINE NO.152 AUGUST 2019
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.123 page 5
Improvement 3: Incorporation of 3-D printing in manufacturing custom waveguides. Waveguides require geometrically exact dimensions for safe and efficient transfer of microwaves. Their dimensions are dependent on the frequency of the waves they are designed for.
Figure 6: Waveguides for 2450 MHZ and for 915 MHZ (Top) and 3D printed waveguide with built-in bends and sweeps (bottom)
Figure 7: 3-D metallic waveguide model
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