Simulasi kolom distilasi Sieve Tray dengan equilibrium-based model dan rate-based mod

Widodo, Ari (2006) Simulasi kolom distilasi Sieve Tray dengan equilibrium-based model dan rate-based mod. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Beberapa metode rigorous untuk pemisahan kontinu, steady-state, multikomponen, multistage berdasarkan neraca material komponen, neraca energi, korelasi termodinamika, dan kesetimbangan fase telah banyak dibahas dan dipublikasikan. Namun, kebanyakan metode yang digunakan adalah berdasarkan pada asumsi kesetimbangan tercapai pada setiap stage, berkaitan dengan transfer massa dan panas komponen. Kecuali bila temperatur berubah secara signifikan dari stage ke stage, asumsi keseragaman temperatur fase uap dan liquid yang meninggalkan suatu stage biasanya dapat diterima. Namun, dalam dunia industri, asumsi kesetimbangan yang berkaitan dengan komposisi fase keluar stage tidaklah beralasan. Secara umum, fraksi mol fase uap yang keluar stage tidak dihubungkan dengan fraksi mol fase liquid yang keluar stage melalui perhitungan K-value. Oleh karena itu, dibutuhkan metode perhitungan kolom yang mengurangi asumsi-asumsi kesetimbangan tersebut.

Kunci model nonequilibrium (mass-transfer-rate-based) model adalah bahwa neraca material dan neraca energi komponen setiap fase diselesaikan bersamaan dengan persamaan-persamaan laju perpindahan massa dan energi dan hubungan-hubungan kesetimbangan pada interface fase untuk memperoleh pemisahan aktual pada setiap stage secara langsung. Hal ini membuat perhitungan efisiensi stage menjadi tidak perlu.

Dari simulasi yang dilakukan, diketahui bahwa tidak ada korelasi khusus yang menghubungkan antara profil temperatur yang diprediksi menggunakan equilibrium-based dan rate-based model, namun kedua metode ini memberikan hasil yang sama untuk perhitungan laju alir uap dan liquid pada setiap stage kolom distilasi. Prediksi komposisi produk distilat dan bottom dari kedua metode menunjukkan hasil yang sama bila jumlah stage dianggap tak terhingga. Namun, untuk jumlah stage tertentu, baik komposisi produk distilat dan bottom maupun profil komposisi kedua fase dalam kolom distilasi antara prediksi equilibrium-based dan rate-based model memperlihatkan hasil yang berbeda. Prediksi profil dan komposisi produk akan memberikan hasil yang relatif sama dengan prediksi rate-based bila menggunakan prediksi equilibrium-based + efisiensi.
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Rigorous equilibrium-based models for continuous-flow, steady-state, multicomponent, multistage distillation based on component material balances, energy balances, and thermodynamic correlations and criteria for phase equilibria are available in the literature. Unfortunately, most of the models assume that equilibrium is achieved at each stage with respect to both heat and component mass transfer. Except when temperature changes significantly from stage to stage, the assumption of temperature equality for vapor and liquid phases leaving a stage is usually acceptable. However, in most industrial applications, the assumption of equilibrium with respect to exiting phase compositions is not reasonable. In general, exiting vapor-phase mole fractions are not related to exiting liquid-phase mole fractions by thermodynamic K-values. Thus, a new model that reduces equilibrium assumptions for distillation column calculations is needed.

The key feature of nonequilibrium (mass-transfer-rate-based) models is that the component material balances and energy balances for each phase are solved together with mass and energy transfer rate equations and equilibrium relations for the phase interface to find the actual separation on each stage directly. This makes the calculation of stage efficiencies unnecessary.

From the simulations performed, it was found that there are no specific correlations between the temperature profiles calculated from the equilibrium-based and rate-based approaches, but both methods give appropriate results for the calculation of flow rate profiles at each stage of the distillation column. It was also found that, for a column with an infinite number of stages, the predicted distillate and bottom compositions calculated using the rate-based approach were the same as those calculated using an equilibrium model. A substantial difference in the distillate and bottom compositions calculated using the different methods was observed for a column with a specified number of stages. The product compositions and profiles predicted by the rate-based model agreed with those of the equilibrium-based model when a stage efficiency was incorporated into the equilibrium relations.

Item Type:	Thesis (Other)
Additional Information:	660.284 25 Wid s
Uncontrolled Keywords:	rate-based, mass transfer, equilibrium-based model, nonequilihrium, sieve tray, distilasi, rate-based, mass transfer, equilibrium-based model, nonequilibrium, sieve tray, distillation
Subjects:	T Technology > TP Chemical technology > TP156 Crystallization. Extraction (Chemistry). Fermentation. Distillation. Emulsions.
Divisions:	Faculty of Industrial Technology > Chemical Engineering > 24101-(S2) Master Thesis
Depositing User:	magang .
Date Deposited:	07 Oct 2026 02:05
Last Modified:	07 Oct 2026 02:05
URI:	http://repository.its.ac.id/id/eprint/145361

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