This invention relates to water purification systems and, in particular, to such systems that purify raw water by distillation.
Systems that purify water by distillation, in which raw water is converted to steam in a boiling tank and the steam subsequently converted to treated water, are well-known in the art.
In one such distillation water purification system developed by the inventors of the present invention, water is admitted to the boiling tank in periodic batches in response to a tank probe that indicates the need for additional raw water. Whenever such a batch is admitted, the head of steam in the apparatus has a tendency to collapse. This phenomena is disruptive to the distillation process, can cause stress on components of the apparatus and emits a displeasing sound. In addition, the apparatus must be periodically de-energized and the boiling tank drained to remove salts and minerals that have accumulated in the raw water.
In a prior art water purification system, disclosed in U.S. Pat. No. 3,055,810 to Ross E. Skow, raw water is supplied to the apparatus in excess of the amount required for the distillation process. The excess raw water is disposed to a drain through a pipe mounted at a desired water level. Because the excess raw water is circulated through the boiling tank, contaminants in suspension therein will be removed with the excess water. However, any contaminants that precipitate out of the raw water will accumulate in the bottom of the boiling tank and must be periodically removed.
In another such system disclosed in U.S. Pat. No. 3,505,173, issued to Forrest Thompson Randell, a salinometer is provided for a water distillation plant to monitor the purity of the treated water. When the treated water is not of a desired quality, an output pump is disabled and the impure condensate is fed back to the boiling tank for re-distillation.