Parex Unit Feed

Abstract

A process for separating a product from a multicomponent feedstream to an adsorption apparatus or system. The apparatus or system may comprise a moving-bed or a simulated moving-bed adsorption means. The product comprises at least one organic compound, such as an aryl compound with alkyl substitutes. In embodiments the conduits used to supply the feedstream to the apparatus or system are flushed with media of multiple grades. In embodiments the process achieves improvements in one or more of efficiency of adsorption separation, capacity of adsorption apparatus systems, and purity of product attainable by adsorption process.

1 . A process for separation of hydrocarbon material from at least two separate sources of feed, the process comprising the steps of: (a) introducing a first multicomponent feed, comprising at least one desired product, through at least one fluid communication conduit into a apparatus comprising plural sieve chambers fluidly connected with plural bedlines A1 through An+j, wherein n>2 and n+j is the total number of bedlines, which in turn are fluidly connected with a matrix of fluid communication conduits to distribute plural input streams, including desorbent, a primary flush input and a secondary flush input, and at least two multicomponent feeds differing in the concentration of paraxylene, to said plural bedlines, and plural output streams, including a primary flush output and a secondary flush output, an extract comprising a paraxylene-enriched product, and raffinate, from said plural sieve chambers; (b) flushing the at least one conduit in step (a) with a sufficient quantity of at least one initial flushing medium comprising the at least one desired product in step (a) in an initial concentration, such that feed residue is flushed from the at least one conduit in step (a) into the apparatus by the at least one initial medium; (c) flushing the at least one conduit in step (a) with a sufficient quantity of a second flushing medium, wherein said second flushing medium is selected from the group consisting of desorbent, and a flushing medium comprising the at least one desired product in step (a) in a final concentration, such that the final concentration is not less than the initial concentration and such that initial medium residue from the at least one initial medium is flushed from the conduit in step (a) into the apparatus by the final medium; (d) withdrawing the at least one desired product in step (a) from the apparatus; (e) introducing a second multicomponent feed comprising at least one desired product, which may be the same or different from the at least one desired product in step (a) and which, if the same, is present in the second multicomponent feed in a concentration different from the concentration of the at least one desired product in said first multicomponent feed, through at least one fluid communication conduit into the apparatus; (f) flushing the at least one conduit in step (d) with a sufficient quantity of at least one initial flushing medium (which may be the same or different from the flushing medium in step (b)) comprising the at least one desired product in step (e) in an initial concentration, such that feed residue is flushed from the at least one conduit in step (e) into the apparatus by the at least one initial medium in step (f); (g) withdrawing the at least one desired product in step (d) from the apparatus;
 the improvement comprising: when bedline An contains extract, bedline An+9 contains a first multicomponent feed, bedline An+7 contains a second multicomponent feed, then said secondary flush input is contained in a bedline between bedlines An+2 and bedline An+7.   
     
     
         2 . The process of  claim 1  wherein the quantity of said initial medium is greater than that sufficient to flush said feedstream residue from said conduit. 
     
     
         3 . The process of  claim 2  wherein said apparatus has a sieve chamber capacity and the quantity of said initial medium is sufficient to fill said apparatus to said sieve chamber capacity. 
     
     
         4 . The process of  claim 3  wherein said desired component is an organic compound. 
     
     
         5 . The process of  claim 4  wherein said organic compound is an C 8  aromatic isomer. 
     
     
         6 . The process of  claim 5  wherein said C 8  aromatic isomer selected from a group consisting of metaxylene, orthoxylene, and paraxylene. 
     
     
         7 . The process of  claim 1  wherein said apparatus has a sieve chamber capacity and the quantity of said initial medium is sufficient to fill said apparatus to said sieve chamber capacity. 
     
     
         8 . The process of  claim 1  wherein the first multicomponent feed has a concentration of PX of about 23 wt % and the second multicomponent feed has a concentration of PX of above about 80 wt %, and wherein the secondary flush in step (c) comprises about 100 wt % PDEB. 
     
     
         9 . (canceled)