Thin film evaporator

Abstract

A thin film evaporator has a shell with tubes extending through the shell in at least one pass. The shell has a top and a bottom. Process fluid flows through the tubes. A suction from a compressor is applied to the top of the shell at a refrigerant outlet. Refrigerant is introduced into the shell at the bottom and is distributed across the bottom region of the shell. The refrigerant flows up and contacts the tubes, exchanging heat therewith before flowing out of the shell top. Oil in the refrigerant contacts the shell wall and drains into a sump.

1 . A thin film evaporator, comprising:
 a) a shell having two ends, a top and a bottom;   b) a plurality of tubes located in the shell and extending between the two ends, the tubes forming a path through the shell, the path comprising at least one pass through the shell;   c) at least one refrigerant inlet located in the bottom of the shell;   d) a refrigerant distributor connected to the refrigerant inlet and located between the shell bottom and the tubes, the distributor having openings facing the shell bottom;   e) a perforated plate between the distributor and the tubes;   f) at least one refrigerant outlet located in the shell top;   g) a suction applied to the refrigerant outlet.   
     
     
         2 . The thin film evaporator of  claim 1 , wherein the distributor openings are sized so as to produce a spray of refrigerant. 
     
     
         3 . The thin film evaporator of  claim 1 , further comprising a thin film of liquid refrigerant on the tubes, with vapor refrigerant in between the tubes. 
     
     
         4 . The thin film evaporator of  claim 1 , further comprising a demister located in the shell between the tubes and the refrigerant outlet. 
     
     
         5 . The thin film evaporator of  claim 4 , wherein the tubes comprise a main body of tubes, further comprising a super heat body of tubes located between the demister and the refrigerant outlet. 
     
     
         6 . The thin film evaporator of  claim 1 , further comprising a sump located in the bottom of the shell. 
     
     
         7 . A method of heat exchange using a thin film evaporator having a shell with two ends, a top and a bottom, a plurality of tubes in the shell and extending between the ends, comprising the steps of:
 a) flowing a process fluid through the tubes;   b) flowing refrigerant into the bottom of the shell;   c) distributing the refrigerant across a bottom region of the shell;   d) providing a film of refrigerant around the tubes and affecting heat transfer between the process fluid and the refrigerant;   e) allowing the refrigerant to exit the top of the shell through a refrigerant outlet;   f) applying a suction at the refrigerant outlet.   
     
     
         8 . The method of  claim 7 , wherein the step of distributing the refrigerant across a bottom region of the shell further comprising spraying the refrigerant against the shell. 
     
     
         9 . The method of  claim 8 , wherein the step of distributing the refrigerant across a bottom region of the shell further comprising passing the refrigerant spray through a perforated member before flowing the refrigerant around the tube. 
     
     
         10 . The method of  claim 7 , further comprising the step of providing a resistance to flow in the shell between the tubes and the refrigerant outlet. 
     
     
         11 . The method of  claim 10 , further comprising the step of coalescing liquid at the top of the shell before exiting through the refrigerant outlet. 
     
     
         12 . The method of  claim 10 , wherein the tubes comprise a main body of tubes, further comprising the step of providing a super heat body of tubes between the resistance and the refrigerant outlet. 
     
     
         13 . The method of  claim 7 , wherein the refrigerant comprises oil, wherein:
 a) the step of flowing refrigerant into the shell further comprises spraying the refrigerant against the shell before flowing the refrigerant to the tubes;   b) draining the oil into a sump in the shell.