Reflux condenser

Abstract

Methods, apparatus, and processes are provided for a condenser including flowing a vapor stream including formaldehyde into a tube bundle in a vertical upflow reflux condenser, where a tube in the tube bundle has a length to outside diameter ratio of greater than about 170:1, flowing a cooling fluid on a shell-side of the vertical upflow reflux condenser to condense at least a portion of the vapor stream, where the condensed portion of the vapor stream forms a wetted tube internal surface area on each tube in the generally upright tube bundle; and maintaining the vapor stream velocity at a rate that provides a liquid residence time where formaldehyde condensed on the wetted internal surface area of each tube can react with water to form methylene glycol, removing at least sixty percent (60%) of formaldehyde from the vapor stream fed to the condenser.

1 . A method of operating a condenser, comprising:
 flowing a vapor stream at a vapor stream velocity into a generally upright tube bundle in a vertical upflow reflux condenser, where the vapor stream includes formaldehyde and where a tube in the tube bundle has a length to outside diameter ratio of great than about 170:1;   flowing a cooling fluid on a shell-side of the vertical upflow reflux condenser to condense at least a portion of the vapor stream;   forming a wetted tube internal surface area on each tube in the generally upright tube bundle with the condensed portion of the vapor stream;   maintaining the vapor stream velocity at a minimum of one hundred percent of a critical exit entrainment velocity to entrain liquid from the wetted tube internal surface area into liquid droplets and to carry the liquid droplets out of the tube bundle;   collecting the liquid droplets of the condensed portion of the vapor stream carried out of the tube bundle as a liquid reflux on a top tubesheet positioned at a top of the tube bundle;   flowing the liquid reflux from the top tubesheet down the internal surface area of each tube in the tube bundle in a direction countercurrent to the vapor stream; and reacting the formaldehyde in the vapor stream with water in the condensed portion of the vapor stream and the liquid reflux on the wetted tube internal surface area to form methylene glycol.   
     
     
         2 . The method of  claim 1 , where flowing the vapor stream into the generally upright tube bundle includes flowing the vapor stream such that a vapor stream exit velocity is in excess of a critical exit entrainment velocity to form the wetted tube internal surface area on each tube in the generally upright tube bundle. 
     
     
         3 .- 4 . (canceled) 
     
     
         5 . The method of  claim 1 , where the vapor stream velocity is about 8.5 feet per second (2.59 meters per second) or less. 
     
     
         6 . The method of  claim 1 , where the vapor stream velocity is about ninety percent (90%) or less of a calculated critical flooding velocity at an inlet of the tube bundle. 
     
     
         7 . The method of  claim 1 , where the method includes removing at least about eighty percent (80%) formaldehyde from the vapor stream fed to the condenser. 
     
     
         8 . The method of  claim 1 , where the method includes removing at least about eighty-five percent (85%) formaldehyde from the vapor stream fed to the condenser. 
     
     
         9 . The method of  claim 1 , where a liquid residence time is at least about 0.5 seconds. 
     
     
         10 . A condenser comprising elements arranged, sized, and dimensioned to remove at least sixty percent (60%) formaldehyde from a vapor stream fed to the condenser, comprising:
 a main body defining a cooling zone, where the main body includes a cooling fluid inlet and a cooling fluid outlet to pass a cooling fluid on a shell side of the condenser;   a generally upright tube bundle disposed in the cooling zone to receive the vapor stream, where the tube bundle provides an internal surface area for condensing at least some of the vapor feed as heat is removed by the cooling fluid, and the tube bundle has a ratio of total tube internal surface area to tube internal volume of at least approximately 20:1 1/[length]; and   a top tubesheet positioned at a top of the tube bundle, where the internal surface area provides a wetted internal surface area on which formaldehyde in the vapor stream reacts with water on the wetted internal surface area to form methylene glycol.   
     
     
         11 . The condenser of  claim 10 , where each tube in the tube bundle includes a tapered bottom portion. 
     
     
         12 . The condenser of  claim 10 , where each tube in the tube bundle has a length to diameter ratio of at least approximately 150:1. 
     
     
         13 . The condenser of  claim 10 , including a number of baffles for supporting the tube bundle. 
     
     
         14 . The condenser of  claim 10 , where the condenser includes baffles numbering in a range from approximately 10 to 20. 
     
     
         15 . The condenser of  claim 10 , where the condenser is located inside an ethylene oxide recovery column between a stripping portion that produces the vapor stream and a reabsorbing portion of the column. 
     
     
         16 . The condenser of  claim 15 , where the vapor stream includes ethylene oxide, and an ethylene oxide rich vapor stream exiting the condenser is at least 85 mole percent ethylene oxide. 
     
     
         17 . The condenser of  claim 16 , where the condenser is coupled to the reabsorbing portion of the ethylene oxide recovery column. 
     
     
         18 . The condenser of  claim 10 , where each tube in the tube bundle has an outside diameter in a range of about 1 inch to about 2 inches. 
     
     
         19 . The condenser of  claim 10 , where formaldehyde in the vapor stream reacts with water on the wetted internal surface area to form methylene glycol, removing at least eighty percent (80%) of formaldehyde in the vapor stream fed to the condenser.