Propane recovery

Essentially all of the methane [74-82-8] is removed ia the demethanizer overhead gas product. High recovery of ethane and heavier components as demethanizer bottoms products is commonplace. The work that is generated by expanding the gas ia the turboexpander is utilized to compress the residue gas from the demethanizer after it is warmed by heat exchange with the inlet gas. Recompression and deUvery to a natural gas pipeline is performed downstream of the plant. A propane recovery of 99% can be expected when ethane recoveries are ia excess of 65%. 

The settling of the acid sludge in the presence of propane is said to be sufficiently complete to allow neutralization with a small amount of fine-meshed clay, which is introduced into the acid oil-propane solution and passes with the oil through the propane recovery unit. The clay is removed from the oil by conventional filtration to produce a finished bright stock with a good color (48). 

Propylene from propane Reduced reaction temperature, elimination of propane recovery 2,794 20.23 0.057... 

When investigating the abstracts, an article should not be eliminated on the basis of a title alone for these are often deceptive. For example an article entitled The Utilization of Benzene may contain detailed information on its commercial production. An article entitled XYZ Company produces 180,000,000 million lbs. of ethylene may simply be an announcement that the plant is operating, but again, it may contain a highly detailed description of the plant itself, construction materials used therein, and results of operations. More Propane Recovery may be merely a half-column story stating that more propane is being recovered from a specific plant, but it could also be a highly technical article on how the result is accomplished. 

It is essential, however, for defining the column performance, not only for the specification to be feasible, but for a unique solution to exist. If, for instance, the propane recovery in the bottoms is specified at 100%, no unique solution exists since any lean oil rate over about 800 mol/h satisfies the specification. 

The column has two feeds, as in Example 9.1, but in this application the feeds are of very different average boiling points, and they enter the column at about the same temperature. The oil feed has the higher boiling point and is fed at the top of the column as external reflux, while the gas mixture is fed at an intermediate tray. The top section of the column between the two feeds is the absorption section where most of the propane recovery takes place. The lower section, between the gas feed and the reboiler, is the reboiled stripping section where ethane and lighter components are stripped off as in conventional columns. 

Assuming a fixed-configuration, fixed-pressure column, there could still be two independent operating variables the reboiler duty and the oil feed rate. These two parameters may be varied independently to meet the specified propane recovery and ethane rejection in the bottoms. Although all the parameters are... 

Specifications Propane recovery in bottoms 95% ethane mole fraction in bottoms 0.003. 

An intermediate product such as the upper side draw, which is mostly propane, may contain impurities from components both lighter and heavier than the main component. The upper side draw is at the same time the bottom product of the top column section and the top product of the second section. The fractionation in the upper section determines to what extent ethane is stripped off from the propane product, and the fractionation in the second section determines to what extent butane is removed from the propane product. Again, in this situation since the number of stages in each section and the reflux ratio are all fixed, the fractionation is fixed. The propane recovery and purity depend mostly on its flow rate and on the flow rates of the adjacent products above and below it. If the propane product contains too much ethane, its flow rate should be cut back and the overhead rate increased. If the propane product contains too much butane, its flow rate should be cut back and the lower side draw rate increased. Table 9.14 summarizes the purities of components in different products at different flow rates. The recoveries can also be calculated from Table 9.14. The dependence of the other products compositions on their rates may be analyzed in a similar manner. 

The recovery is based on C02 rejection column being operated for ethane reflection/propane recovery. 

The Edmister method predicts ethane and propane recoveries of 98.5% and 97.7%, respectively, compared to values of 98.8% and 98.1% by the exact method. 

Overhead Recycle (OHR) Process- the OHR has often been used instead of GSP for Propane recovery from Natural gas. Although typically used in a two column configuration, this process essentially withdraws a vapor stream from an intermediate point in the column that is then condensed and used as a reflux for the upper portion of the first column. This again produced cold liquids to contact and rectify the vapor leaving the expander, the absorbing the propane plus components for recovery in the bottom product of the second column. 

Other processes like Randall High pressure absorber process for propane recovery and shell deep LPG Recovery process (SHDL) are employed in industries. 

A third independent equation is provided by the specification on propane recovery ... 

The most common method of producing ethylene commercially is high temperature coil cracking of propane or of a mixture of ethane and propane. Recovery of ethylene from the cracked gases is often accomplished by low temperature, high pressure straight fractionation. Another customary manufac-... 

The total effect of the high pressure separator and the turboexpander flash calculations is shown by the estimated ethane recovery in Table IV which varies from 82.1% to 88,4%. The estimated propane recovery for all cases is 99+%. 

The bottoms liquid from the deethanizer serves as the principal feed to the depropanizer. A second feed stream to this column consists of the bottoms liquid from the condensate stripper for the fourth and fifth compression stages. The primary function of this column is propylene and propane recovery from these two feeds. The column operating pressure typically will be 240 to 340 psia, which is sufficient to condense the over-... 

The descriptive term reboiied absorber is somewhat misleading in describing the function, although it is the name most commonly used. Another descriptive name and the one most often used in the hydrocarbon processing industries is rich oil demethanizer where high ethane recovery is attained or rich oil deethanizer when propane recovery is practiced in either case, the abbreviation ROD is often used. The most accurately descriptive name but, unfortunately, the one least used now is stripper-reabsorber. 

The design of most natural gas processing plants is based on the recovery of a certain component, usually either propane or ethane. Since both the absorber exit gas and the ROD overhead gas contain the base component as the heavy key, the design material balance of those two systems must be interdependent. For example, in setting up the preliminary material balance for a gas plant based on 70 percent propane recovery, the absorber must overabsorb so that there is enough extra propane in the ROD feed to permit a reasonably low lean oil rate to the latter tower. The optimum absorption will result in the lowest total lean oil rate to the absorber and the ROD combined. As a rule-of-thumb, the absorption section of the ROD will have to absorb a minimum of 95 percent of the heavy key vapor feed, including the internal vapor. 

I. Assumes CO2 column operation based on ethane rejection/propane recovery. Source Boustany el al. (1983)... 

McCann. P., Ryan, J. M., and O Brien, J. V., 1987, The Mitchell Alvord South CO2 Plant Propane Recovery—Ryan Holmes, paper 74A presented at the AIChE 1987 Spring National Meeting, Houston, TX, Match 29-April 2. 

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