Secondary wash at discharge drum

Abstract

An apparatus and process is disclosed for the cooling of a reactor effluent gas stream. The apparatus includes a contact cooling system with a discharge drum providing a second wash zone. Each wash zone has a packed bed, or other type of mechanical system for contacting the gas stream with the cooling liquid. The liquid in the first stage will remove heavy components, allowing for a cleaner second stage that can be reduced in size.

What is claimed is: 
     
         1 . An apparatus for contact cooling comprising:
 a vessel having a gas inlet, a gas outlet, a wash oil inlet, and a wash oil outlet;   a first packed bed disposed within the vessel at a position above the gas inlet and below the wash oil inlet;   a discharge drum, having a discharge drum gas inlet in fluid communication with the vessel gas outlet, a discharge drum gas outlet, a drum wash oil inlet and a drum wash oil outlet;   a second packed bed disposed within the discharge drum at a position above the drum gas inlet and below the drum wash oil inlet; and   a demister pad disposed within the discharge drum above the second packed bed and below the discharge drum outlet.   
     
     
         2 . The apparatus of  claim 1  further comprising a compressor having an inlet in fluid communication with the vessel gas outlet and an outlet in fluid communication with the discharge drum inlet. 
     
     
         3 . The apparatus of  claim 2  further comprising a gas cooler having an inlet in fluid communication with the compressor outlet, and an outlet in fluid communication with the discharge drum inlet. 
     
     
         4 . The apparatus of  claim 1  further comprising a plurality of disk and donut trays disposed above the gas inlet and below the first packed bed within the vessel. 
     
     
         5 . The apparatus of  claim 1  further comprising:
 a first wash oil recycle system having an inlet in fluid communication with the wash oil outlet and an outlet in fluid communication with the wash oil inlet. 
 
     
     
         6 . The apparatus of  claim 5  further including a first heat exchanger in the first wash oil recycle system for cooling the wash oil. 
     
     
         7 . The apparatus of  claim 1  further comprising
 a second wash oil recycle system having an inlet in fluid communication with the drum wash oil outlet, and an outlet in fluid communication with the drum wash oil inlet. 
 
     
     
         8 . The apparatus of  claim 7  further including a second heat exchanger in the second wash oil recycle system for cooling the wash oil. 
     
     
         9 . The apparatus of  claim 1  further comprising a fresh wash oil inlet in fluid communication with the drum wash oil inlet. 
     
     
         10 . The apparatus of  claim 1  further comprising a conduit having a conduit inlet in fluid communication with the drum wash oil outlet, and an outlet in fluid communication with the wash oil inlet. 
     
     
         11 . An apparatus for contact cooling comprising:
 a vessel having a gas inlet, a gas outlet, a wash oil inlet, and a wash oil outlet;   a first packed bed disposed within the vessel at a position above the gas inlet and below the wash oil inlet;   a plurality of disk and donut trays disposed above the gas inlet and below the first packed bed within the vessel;   a compressor having an inlet in fluid communication with the vessel gas outlet, and an outlet;   a discharge drum, having a discharge drum gas inlet in fluid communication with the compressor outlet, a discharge drum gas outlet, a drum wash oil inlet and a drum wash oil outlet;   a second packed bed disposed within the discharge drum at a position above the drum gas inlet and below the drum wash oil inlet;   a plurality of disk and donut trays disposed above the gas inlet and below the first packed bed within the vessel; and   a demister pad disposed within the discharge drum above the second packed bed and below the discharge drum outlet and below the drum wash oil inlet.   
     
     
         12 . The apparatus of  claim 11  further comprising a conduit disposed between the compressor outlet and the discharge drum inlet for carrying gas; and
 a cooling unit in thermal communication with the conduit. 
 
     
     
         13 . The apparatus of  claim 11  further comprising a first wash oil recycle system having an inlet in fluid communication with the wash oil outlet and an outlet in fluid communication with the wash oil inlet. 
     
     
         14 . The apparatus of  claim 11  further comprising a second wash oil recycle system having an inlet in fluid communication with the drum wash oil outlet, and in outlet in fluid communication with the drum wash oil inlet. 
     
     
         15 . A process for cooling a reactor effluent stream comprising:
 passing a reactor effluent gas to a contact cooling vessel;   passing a wash oil to the contact cooling vessel, to intermingle with the reactor effluent gas and generate a cooled effluent gas;   passing the cooled effluent gas to a discharge drum;   passing a second wash oil to the discharge drum to intermingle with the cooled effluent gas to generate a washed and cooled gas.   
     
     
         16 . The process of  claim 15  further comprising passing the washed and cooled gas through a demister to generate a cooled gas with droplets removed. 
     
     
         17 . The process of  claim 15  wherein the reactor effluent gas first contacts the wash oil through an oil cascade over disk and donut trays, and then contacts the wash oil through a packed bed. 
     
     
         18 . The process of  claim 15  further comprising:
 passing the cooled effluent gas to a compressor to generate a compressed gas; 
 passing the compressed gas through a heat exchanger to generate a cooled, compressed gas; and 
 then passing the cooled compressed gas to the discharge drum. 
 
     
     
         19 . The process of  claim 15  further comprising:
 collecting the wash oil from the vessel; 
 filtering the wash oil to generate a filtered wash oil; 
 cooling the filtered wash oil to generate a cooled wash oil; and 
 passing the cooled wash oil to the vessel. 
 
     
     
         20 . The process of  claim 15  further comprising:
 collecting the second wash oil; 
 cooling the second wash oil to generate a cooled second wash oil; and 
 passing the cooled second wash oil to the discharge drum.