Optimasi Kondisi Operasi Kolom Destilasi untuk Meningkatkan Konsentrasi Ethylene Dichloride (EDC) Umpan Furnace (Studi di PT Asahimas Chemical)

Ethylene Dichloride (EDC) dengan konsentrasi yang tinggi akan menghasilkan Vinyl Chloride Monomer (VCM) dengan konsentrasi yang tinggi. EDC akan mengalami perengkanhan menjadi VCM didalam peralatan yang disebut furnace. Konsentrasi EDC yang tinggi akan memperpanjang umur furnace karena terdapat lebih sedikit High Boiling Component (HBC) yang mengakibatkan terbentuknya coke. Konsentrasi EDC rata-rata yang ada sebesar 99,6% (w/w). Pada penelitian ini dilakukan simulasi untuk meningkatan konsentrasi EDC di aliran atas kolom distilasi TW-303 lebih besar atau sama dengan 0,2 % (w/w) dari 99,6% (w/w). Optimasi variabel yang dilakukan adalah laju alir refluk kolom distilasi TW-304, tekanan kolom bagian bawah TW-304 dan tekanan kolom bagian atas TW-303. Hasil optimasi menunjukkan dapat dilakukannya peningkatan konsentrasi EDC di aliran atas kolom distilasi TW-303 sebanyak 0,2% (w/w) dengan laju alir 77063,0859 kg/h. EDC dengan konsentrasi tersebut dapat meningkatkan umur furnace sampai dengan 1,5-2 tahun.

ENTRAINER SELECTION FOR SEPARATION OF AZEOTROPIC MIXTURES BY DISTILLATION METHODS

Azeotropic or close – boiling mixtures often preclude conventional distillation as a method of separation. Instead, extractive or azeotropic distillations are commonly used to separate azeotropic or close – boiling mixtures. For the design of those separation units, selecting suitable entrainers (solvents) is a key step. The traditional method for solving this problem is to use experimentation which is time – consuming and expensive. Currently available selection criteria are inadequate. They contradict one another and often lead to incorrect conclusions. Indeed, for a minimum boiling azeotrope, the existing entrainer selection rules state that one should use a high boiling component that introduces no additional azeotrope (Benedict & Rubin, 1945), an intermediate boiling component that introduces no additional azeotrope (Hoffman, 1964), a component which introduces no distillation boundary between the azeotropic constituents (Doherty & Caldarola, 1985), and either a low boiling component that introduces no additional azeotrope or a component that introduces new minimum boiling azeotrope (Stichlmaric, Fair & Bravo, 1989).In this work, Aspen Plus simulator was used to propose an entrainer selection procedure based on the criteria: 1) A good entrainer is a component that eliminates the azeotrope easily (i.e. even when it’s concentration is small). 2) A component that yields high relative volatilities αAB between the two azeotrope constituents.

THEORETICAL RATIONALE FOR THE SELECTION OF THE OPTIMAL SCHEME OF SEPARATION OF THE THREE-COMPONENT MIXTURE

It is theoretically justified that for the scheme of separation of three-component mixtures with the release of the high-boiling component in the first column there is a region of initial compositions for which the heat costs are the least. An expression describing the boundary of the optimality regions of different separation schemes is given. The calculation of the heat costs for both rectification schemes of the three-component mixtures performed using the Aspen Plus software package confirmed the theoretical justification for the existence of optimality regions for each of them. With the help of the concept of internal energy saving, the advantage of one or another scheme of separation of a three-component mixture is explained.