Unlike a painting a machine can be tuned to new requirements without changing its fundamental reason of being.
An interesting book A Culture of Improvement: Technology and the Western Millennium written by Robert Friedel in 2007, reviews the invention and evolution of many technologies. He certainly highlights that many factors determine the course of an idea and that it is not always the best idea that dominates. In school, history classes often gave the impression that there were technological leaps whereas this informed text demonstrates that more often than not inventors or the mechanically inclined stood on the shoulders of others, so to say. Often people that leaped too far did not succeed for various reasons; people did not accept such a change, existing materials did not have the required properties, incompatibility with existing technology, competitors sidetracked "message" etc. In essence many aspects of a development have to be "done right" to assure success.
It is baffling that the author chooses to dismiss the work of Tesla while he lauds laboratory managers who were often credited with the inventions of employees. Design of the distribution infrastructure of alternating current is only stated not credited. Marconi's patent applications were turned down for years because of Tesla's existing patents. His patent was only granted when well connected wealthy business people employed their power to influence. It is not too different to where a federal government concluded that the tomato is a vegetable that is subject to import regulations.
Fluidizing the bed of coffee beans is essential to the proper mixing and even distribution of heat. In the upgrade shown on the right the Blower bearings have a lubrication system to improve the Mean Time Before Failure which usually happened too soon at roasting temperatures.
The continual cleaning of the recirculated air means that the roaster does not emit smoke during the hot weather roasting process. A distinction is made regarding the weather because when it is cooler steam is vented during the bean cooling process. Such a roaster can be used in higher density areas thanks to the built in pollution controls.
Of course the great smell of coffee is not to be wasted therefore we vent the air used to cool the coffee beans straight to the street to act as an olfactory business sign.