Abstract: A concatenable module for a multiple-effect still has a chamber encompassed by four walls and two baffles, where one baffle is shared with the preceeding effect and the other the subsequent effect. Heat exchanger tubes mount into an accumulator which is sealed to a baffle, an aperature in the baffle at the accumulator allows vapors and fluids to flow between modules.A distribution plug seals the top end of a heat exchanger tube while carrying distilland through internal channels until it reaches a ring channel which carries distilland in evenly around the plug. A gap below the ring channel between the plug and tube allow distilland to flow evenly on the tube as it leaves the plug.

Abstract: The method of preparing and operating a heat-exchanging membrane of plastic material as the evaporating and condensing surfaces in a still includes treating the evaporating surface to be wettable by the distilland, and includes selectively washing the condensing surface which is unwettable by the by the distilland in order to promote efficient accumulation of condensed droplets and efficient heat transfer through the membrane to the evaporation surface. Washing liquids of either similar or disimilar chemical composition relative to the condensed vapor are recycled to the upper region of the condensing surface to facilitate washing of the surface by the downward movement of accumulated droplets of condensed vapor.

Abstract: A vapor is condensed onto a condensor whose upper portion promotes film-wise condensation and whose lower portion promotes drop-wise condensation. One embodiment of this invention uses a plastic condensing tube which has a metal condensor pipe inserted into the tube in its upper end. Grooves and aperatures in the wall of the pipe encourage the flow of condensate between the pipe and plastic tube to facilitate heat conduction between the two. Heat conduction between the plastic tube and metal pipe is facilitated by a liquid such as heat-sink grease. An alternate embodiment features a plastic-only heat condensor whose upper portion is treated to make it condense the vapor as a film and whose lower portion is untreated so as to condense the vapor as drops.