Multi-stage economizer

An economizer having a pluraity of stages for flash cooling refrigerant liquid for use in a refrigeration system comprising

• a. housing means defining a plurality of chambers of successively lower pressure, a first chamber being at the highest pressure, and a last chamber at the lowest pressure;
• b. first inlet means for conveying refrigerant liquid into said first chamber which is at the highest pressure;
• c. first outlet means for conveying the cooled refrigerant liquid out of said last chamber which is at the lowest pressure;
• d. second inlet means for conveying refrigerant into each of the chambers except said first chamber;
• e. second outlet means for conveying cooled refrigerant predominantly in the liquid stage, out from each of the chambers except said last chamber;
• f. connecting means for connecting the second outlet means of a chamber of relatively higher pressure together in fluid communication with the second inlet means of a chamber of successively lower pressure, said connecting means including sump means for collecting the cooled refrigerant liquid which flows through said connecting means;
• g. throttling means for restricting the flow of refrigerant into each chamber and thereby reducing its pressure such that a portion of the refrigerant liquid flashes or evaporates as it flows through said throttling means, and thereby cools the liquid refrigerant remaining;
• and
• h. flash gas outlet means disposed near the top of each chamber, and operative to convey flash gas away from that chamber.