 Natural gas is a very important fuel fossil fuel in the United States. Its significance has increased since the hydrofracking operations to produce shale gas as a non-conventional source for natural gas. Now the the production of natural gas through hydrofracking or other techniques is beyond the scope of this course but we will focus on the processing of natural gas as it comes out of the ground. The main component of natural gas is methane but it also contains heavier hydrocarbons, principally ethane, propane, butanes and pentanes which may be referred to as the natural gas liquids. In addition the raw gas could contain significant amounts of water, hydrogen sulfide, carbon dioxide and nitrogen in some cases. So there is a need to process the natural gas as it comes out of the ground before it is sent to or fed into the pipeline system for transport to remote locations. There are essentially four components of natural gas processing which are oil and condensate removal and sulfur and carbon dioxide removal. Sulfur comes out as H2S mainly. Removing water is important and the separation and fractionation of natural gas liquids that's anywhere from butane or propane butane up to pentanes. Now as we have talked about before these natural gas liquids are in a sense new feeds to the refinery as as liquid materials to be blended into practically to gasoline product as an additional feed material. So it's important that we really look at this natural gas processing techniques. Now for processing of natural gas we use pretty much the same techniques as we have in petroleum refining. One major process is of course removal of H2S and carbon dioxide as acid gases. We'll use the amine absorption or solutions that contain the base ethanol amine or diethanolamine to absorb these acid gases H2S and carbon dioxide which are of course sent to sulfur recovery using again the similar techniques that we've talked about for petroleum refining that is the Klaus and then also the Scott method. The separation and fractionation of natural gas liquids uses essentially the same processes as we have talked about in the light ends unit in a petroleum refinery to separate ethane and and butane and propane and the heavier liquids in this unit that's essentially going to be a similar setup as we have talked about in the light ends unit.