Method and apparatus for recovering heat energy from polluted water

摘要

A heat exchanger is provided in the form of cylindrical, hollow panels in upstanding, spaced, concentric relationship for a first medium flow, and a casing surrounding the panels for a second medium flow. The upper edges of the panels are mutually level. The heat exchanger also includes a carrying arm rotatable in the horizontal plane above the upper edges of the panels and carrying vertical cleaning arms extending between the panels. The second medium flow is downwardly taken into the casing under the inmost panel, and is taken out downwards from the casing outside the outmost panel the liquid surface of the second medium flow is allowed to rise to a level between the upper edges of the panels and the lower part of the carrying arm. A substantially constant gas volume is maintained in the casing above the liquid surface of the second medium flow, by arranging a control for sensing the liquid level (25) of the second medium flow. A gas pump (25) is arranged to maintain the gas volume in the casing above the liquid level substantially constant in response to the control.