Extraction apparatus and method thereof

An extraction apparatus for extracting at least one constituent in a substance, comprising:

• an extraction apparatus having an extractor for receiving said substance and a subcritical extraction fluid, said at least one constituent in said substance being dissolved in said subcritical extraction fluid;
• a discharge pipe fluidly coupled to said extractor for receiving said subcritical extraction fluid and said at least one constituent dissolved in said subcritical extraction fluid from said extractor, wherein said discharge pipe accommodates a discharge pump, a valve and an additional heating system;
• an extraction separator fluidly coupled to said discharge pipe for receiving and heating said subcritical extraction fluid and said at least one constituent dissolved in said subcritical extraction fluid from said discharge pipe to gasify said subcritical extraction fluid and separate said at least one constituent and said gasified subcritical extraction fluid;
• an extraction condenser fluidly coupled to said extraction separator for receiving and liquefying said gasified subcritical extraction fluid from said extraction separator, wherein said extractor, said extraction separator and said extraction condenser are operated under constant pressure;
• and
• a circulation pipe fluidly coupled to said extractor and said extraction condenser for receiving said liquefied subcritical extraction fluid from said extraction condenser and sending said liquefied subcritical extraction fluid to said extractor, wherein said circulation pipe comprises a circulation pump, a valve and a heater to preheat the subcritical extraction fluid entering the extractor, wherein said extractor, said discharge pipe, said extraction separator, said extraction condenser and said circulation pipe forming a long circulation loop for said subcritical extraction fluid to circulate therein when said extractor operates in a continuous fluid circulation mode, and said circulation pipe being directly connected with said discharge pipe to form a short circulation loop from said extractor, through said circulation pipe and said discharge pipe for said subcritical extraction fluid to circulate therein when said extractor operates in a soaking and circulation mode.