Apparatus for concentrating waste liquid

An apparatus for concentrating waste liquid, said apparatus comprising:

• an evaporator including an evaporation chamber for concentrating waste liquid, wherein at least a part of said waste liquid is evaporated in said chamber to form a vapor;
• a condenser including a condensation chamber wherein said condensation chamber communicates with said evaporation chamber to receive said vapor, at least a part of said vapor being cooled to form a condensed liquid;
• a pressure reducer connected with at least one of said evaporation chamber and said condensation chamber for reducing pressure therein and for removing said condensed liquid, whereby a concentration of a non-evaporating component in said waste liquid in said evaporation chamber is increased;
• a heat pump circuit having a looped sequence including a compressor, a heat radiating portion, an expander, and a heat absorbing portion, a heat transfer medium circulating through said heat pump circuit, said heat radiating portion including an immersed portion immersed in said waste liquid in said evaporation chamber, and said heat absorbing portion including a cooling portion provided in said condensation chamber, a temperature or a pressure of said heat transfer medium circulating in said heat pump circuit varying in accordance with the concentration of said non-evaporating component in said waste liquid;
• a detector provided downstream of said immersed portion in said heat radiating portion of said heat pump circuit, detecting said temperature or pressure of said heat transfer medium, and generating a detection signal based on said temperature or pressure;
• an auxiliary cooler, provided between said compressor and said expander in said heat pump circuit, cooling said heat transfer medium;
• and
• a controller for controlling said auxiliary cooler and the concentration operation of said apparatus responsive to said detection signal from said detector, said controller stopping the operation of said apparatus when said detection signal reaches a predetermined value signifying that the concentration of said waste liquid has risen to a desired concentration.