General Operating Principle

The Windsor Evaporation Concept utilizes a Mechanical Vapor Recompression (MVR) design and Falling Film (FF) principles. Designed to operate below atmospheric pressure, the system enables an incoming effluent to boil at a relatively low temperature. The resulting vapour gains both heat and pressure energy from a compressor (fan) and is then condensed on the pressure side of the heat transfer element. Latent heat from the condensing side of the surface is transferred to the concentrating side and is used as the heating stream in the same stage.

The Windsor system typically returns 80% to 99% of the waste effluent to the process as clean condensate while reducing the waste water volume to less than 20% to 1% of the original stream. These values are effluent specific and can vary due to wastewater characteristics.

The operating principle of the Windsor evaporator is illustrated in the operational flow diagram, Fig. 1 below.

Wastewater passes through two parallel metal heat exchangers into the unit. In these the heat in the condensate and concentrate is recovered. A circulation pump transfers the heated (or cooled) wastewater to the upper portion of the vessel where it is evenly distributed on the heat transfer element through Windsor's patented liquid distributor.

A portion of the circulated wastewater evaporates on the outer surface of the heat transfer element. The resulting vapour is drawn through a fan compressor to increase the heat/pressure energy and is forced to the inner surface of the heat transfer element where it condenses. Latent heat is transferred to the waste water side of the heat transfer element and the clean condensate is collected for reuse in the process.

The concentrated wastewater falls to the bottom of the vessel where it is recirculated to the heat transfer element while a small part is removed by the concentrate pump for disposal.

The system design pressure is maintained by a standard liquid ring vacuum pump. This pump is also used to remove any incondensable gases. Heat from this gas-vapour mixture is recovered by a plate heat exchanger.