Abstract: Improved product stripping in a catalytic hydrodesulfurization (CHD) product stream is obtained by employing off-gas from the unit as a stripping medium. The compressed off-gas is introduced into the stripper below the stripper feed level. The stripper may be operated at pressures higher than those previously employed in CHD product strippers and this permits LPG recovery to be maximized with lower product sulfur levels and reduced load in the off-gas compressor.

Abstract: A process for in situ retorting of oil shale wherein an externally heated gas is circulated through a first retort zone. Surface retorting units comprised of compressors and furnaces are used to start the retorting process and to continue same until the off gas being recovered from the first retort zone reaches a temperature condition which is indicative that adequate heat is available in the retort zone to complete the retorting process without further external heating of the retorting gas. The surface retorting units are then replaced with frontal advance units comprised of low head fans which are capable of circulating the required volume of retorting gas but which require substantially less power to operate than the compressors. Also, when the units are interchanged the off gas from the first retort zone is diverted through a second retort zone to cool the off gas and to preheat the second zone.

Abstract: A method for converting lower alcohols to ethers and hydrocarbons in an exothermic restricted process control arrangement with efficient utilization of process generated heat is described.