you almost never see calandrias on small scale because they need to be a certain minimum size in order to work the way they are supposed to. the idea behind them is to create a small area or container inside the boil kettle (or sometimes outside) that acts like a pressure cooker. this raises the boiling point of the wort, and lets you superheat it. then when the superheated wort exits the calandria, where the pressure is reduced, it errupts into a vigorous boil (which is otherwise hard to achieve in, say, a 3000 gallon tank). the higher the temperature you can achieve, the more DMS will be driven off (also helps the additional surface area from the vigorous sub-surface boil), and the faster you will evaporate some volume. so you can do a 60 minute boil where normally you would have to do 90 minutes. in a production environment, 33% is a huge advantage.
small scale operations dont have the wieght of thousands of gallons of wort to use to make an internal one work passively like they normally do. you need a pressure gradient from the top to the bottom of the wort column. the only way to do it small scale is like klaude said; with a pump and external chamber, and probably a spunding-type valve on the exit to create an area of increased pressure inside. but at that point- its pretty easy to get a vigorous boil at our scale, so theres no need for the extra equipment and hassle.
also that top deflector right above the output stack is normally under the surface of the liquid, so its not shooting up like a fountain (HSA).
