Oil shale retort flue gas cooling and cleaning

Abstract

A technique is provided for cooling the flue gas or off gas from the bottom of an in situ oil shale retort. The gas is collected in a conduit that has a vertical portion through which the gas flows upwardly. It is then withdrawn from the retort through a gas tight bulkhead. Water is sparged downwardly through the vertical portion of the conduit for cooling and cleaning the gas. Means are provided for draining the sparged water into a sump at the bottom of the retort wherein oil and water are collected. Water and oil are separated and the water may be recycled for additional cooling.

What is claimed is: 
     
       1. Apparatus for cleaning and cooling flue gas from an in situ oil shale retort comprising: a tunnel at the bottom of the retort;   a sump in the floor of the tunnel for collecting oil and water from the retort;   a gas tight bulkhead in the tunnel beyond the sump for preventing escape of flue gas from the retort;   a conduit for collecting flue gas from the bottom of the retort having at least a vertical portion in the tunnel through which collected flue gas flows upwardly and a portion passing through the bulkhead for withdrawing flue gas from the retort;   a sparger .[.at the top of.]. .Iadd.in .Iaddend.the vertical portion of the conduit for spraying water downwardly through the vertical portion countercurrent to the flue gas; and   means for draining the sparged water into the sump.   
     
     
       2. An apparatus as defined in claim 1 wherein the vertical portion of the conduit is inside the bulkhead over the sump. 
     
     
       3. Apparatus as defined in claim 1 further comprising a closed stub above the vertical portion of the conduit and wherein the sparger is in the closed stub. 
     
     
       4. Apparatus as defined in claim 1 further comprising: means for removing oil and water from the sump;   means for separating the oil and water; and   means for recirculating the water to the sparger.   
     
     
       5. A method of cooling and cleaning flue gas from an in situ oil shale retort having a top air inlet, a bottom flue gas outlet, a sump at the bottom for collecting oil and water from the retort, and means for gas sealing the bottom of the retort comprising the steps of: collecting flue gas in a conduit adjacent the bottom of the retort inside the means for gas sealing;   passing the collected flue gas upwardly;   spraying water downwardly countercurrent to the upwardly flowing flue gas;   withdrawing the flue gas through the means for gas sealing; and   draining the water into the sump.   
     
     
       6. A method as defined in claim 5 further comprising the steps of: removing oil and water from the sump.   separating the oil and water; and   recirculating the separated water for the spraying step. .Iadd. 7. An apparatus as defined in claim 1 wherein the sparger is located at the top of the vertical portion of the conduit. .Iaddend.