Lean oil still

Problem A lean oil still had unstable control and erratic operation. 

Gas processing Lean oil still Column did not achieve required separation because of insufficient refliK induced ly an undersized reflux orifice plate. Problem was difficult to diagnose because of unusual behavior of top temperature. In some multicomponent distillations, normal top and bottom temperature can be observed even if adequate separation is not achieved. 

Gas processing Lean oil still An added preheater which performed better than design caused column to hiccup and empty itself out every few hours either fixnn the tc or bottom. Oversized preheaters can cause fractionation difficulties. Bypasses around preheaters can eliminate this problem. 

The ROD is similar to a cold feed stabilizing tower for the rich oil. Heat is added at the bottom to drive off almost all the methane (and most likely ethane) from the bottoms product by exchanging heat with the hot lean oil coming from the still. A reflux is provided by a small stream of cold lean oil injected at the top of the ROD. Gas off the tower overhead is used as plant fuel and/or is compressed. The amount of intermediate components flashed with this gas can be controlled by adjusting the cold loan oil retlux rate. 

Absorber oil then flows to a still where it is heated to a high enough temperature to drive the propanes, butanes, pentanes and other natural gas liquid components to the overhead. The still is similar to a crude oil stabilizer with reflux. The closer the bottom temperature approaches the boiling temperature of the lean oil the purer the lean oil which will be recirculated to the absorber. Temperature control on the condenser keeps lean oil from being lost with the overhead. 

Hence the absorption factor A at 4000 B/D is also doubled, but the number of theoretical stages is still 10. Again we refer to the chart and this time plot the condition at the new lean oil rate of 4000 barrels per day. (See Fig. 50.8.)... 

Lean oil from the still is pumped through a heat exchanger and cooler and back to the absorber. Vapors from the still are cooled with partial condensation by indirect heat exchange with the rich oil. The condensate is passed to a separator, which removes water, and the liquid hydrocarbons are returned to the still as reflux. The partially cooled vapors are then passed to the benzol condenser where relatively complete condensation is obtained by the use of cooling water. In this particular plant, the condensate and noncondensed vapors are then passed through a vacuum pump to a separator. From this, noncondensed gases are returned to the fuel gas main, water condensate is removed for disposal, and the hydrocarbon layer is transferred to the crude-benzol storage tanks. 

Rich stripper gas Condenser for steam gasoline Stripper reflux Stripping steam Stripping still Rich-oil neater Heat exchange Lean-oil cooler... 

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