Refinery vent gases

Refinery Vent Gases. Refinery vent gases arise from a variety of sources. The approximate yields from these various sources are shown in Table IV (71). 

The ethylene feedstock used in most plants is of high purity and contains 200—2000 ppm of ethane as the only significant impurity. Ethane is inert in the reactor and is rejected from the plant in the vent gas for use as fuel. Dilute gas streams, such as treated fluid-catalytic cracking (FCC) off-gas from refineries with ethylene concentrations as low as 10%, have also been used as the ethylene feedstock. The refinery FCC off-gas, which is otherwise used as fuel, can be an attractive source of ethylene even with the added costs of the treatments needed to remove undesirable impurities such as acetylene and higher olefins. Its use for ethylbenzene production, however, is limited by the quantity available. Only large refineries are capable of deUvering sufficient FCC off-gas to support an ethylbenzene—styrene plant of an economical scale. 

Chlorsorb Also called RVG Chlorsorb [Regenerator Vent Gas], A process for removing chlorine compounds (mainly HC1) from the waste gases from the CCR Platforming process. The chlorides are reabsorbed on the catalyst. Developed by UOP and now operated in several oil refineries in the United States and Argentina. 

The Stretford process was jointly developed in the l9S0s in the UK by the North Western Gas Board (now the British Gas Corporation) and the Clayton AnilitK (Company, Ltd. It was originally conceived to replace the iron oxide boxes used for the removal of hytfaogen sulfide from coke-oven gas. However, the process proved to be equally suitable for desulfurization of a variety of other gas streams, such as refinery gas, geothermal vent gas, natural gas, and... 

Removing external streams. If gas comes from another unit or vents from a column in the gas concentration unit, consider routing it to the interstage rather than the suction. The refinery needs to evaluate if external streams are worth recovering or whether they can be routed elsewhere. 

Air emissions from a petroleum distillation unit include emissions from the combustion of fuels in process heaters and boilers, fugitive emissions of volatile constituents in the crude oil and fractions, and emissions from process vents. The primary source of emissions is combustion of fuels in the crude preheat furnace and in boilers that produce steam for process heat and stripping. When operating in an optimum condition and burning cleaner fuels (e.g., natural gas, refinery gas), these heating units create relatively low emissions of sulfur oxides, (SO c), nitrogen oxides (NO c), carbon monoxide (CO), hydrogen sulfide (H2S), particulate... 

Sulfa-Hitech . [Atochem N. Am.] Stti-vent used to disstdve sulfur in the prod, (tf sour gas vrelb, in sour-gas pipdines, and in refinery and chemical plant flowlines. 

Fired reboilers are principally used in refineries. Usually, these are fired with a mixtime of gases vented from various units, supplemented by natural gas. A problem with direct-fired reboilers is variation of heat input due to changes in fuel gas composition. For this reason, it may be unsatisfactory to control the fuel flow rate to the furnace, and heat input control may be necessary. 

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