Simulasi Tungku Gasifikasi Tipe Natural Draft Berbasis Model Efek Cerobong dan Keseimbangan Termokimia

Leopold Oscar Nelwan, Dyah Wulandani, Edy Hartulistiyoso, Sri Endah Agustina, Dziyad Dzulfansyah, Erlanda Augupta Pane

Abstract


Abstract
This study was aimed to simulate a novel configuration of gasification stove with the natural draft principles (natural draft gasification or called as NDG stove) based on chimney effect and thermochemical equilibrium modeling. The thermochemical equilbrium model used general stoichiometric gasification,
methanation and water-gas shift equations and their equilibrium constant equations as well as the general energy balance equation. Those equations were coupled with the chimney effect equation and then solved to obtain the reaction coefficients, equilibrium constants, reaction temperature as well as the mass flow rate of air. Simulation was performed by using VBA programming codes in Excel. Subsequently, a stove was built in order to obtain the charcoal consumption rate data which is required to validate the model. The test results showed that the combustion rate was constant i.e. 8.8 g/min and the quality of the flame of the stove was visually good. The calculation result showed that the model could succesfully predict the product gases including CO, CH4, CO2, O2, N2 and other gases. The simulation showed that by using lower stove
height (0.5 and 0.4 m) the combustible gases (CO, H2 and CH4) compositions were increased in such a way that with same combustion rate the potential heat of gas increased from 2.33 kW at stove height of 0.6 m to 2.63 kW at 0.4 m.


Abstrak
Penelitian ini bertujuan untuk mensimulasi tungku gasifikasi dengan konfigurasi baru yang menggunakan prinsip natural draft (tungku natural draft gasification atau disebut sebagai tungku NDG) didasarkan pada
pemodelan efek cerobong dan keseimbangan termokimia. Model keseimbangan termokimia menerapkan persamaan stoikiometri untuk gasifikasi, methanation dan water-gas shift, persamaan-persamaan konstanta keseimbangannya serta persamaan neraca energi umum. Persamaan-persamaan tersebut digabungkan dengan persamaan efek cerbong dan dipecahkan untuk memperoleh koefisien reaksi, konstanta keseimbangan, suhu reaksi dan laju aliran massa udara. Selanjutnya tungku tersebut dikonstruksi dan diuji untuk memperoleh data laju konsumsi arang yang dibutuhkan untuk validasi model. Hasil pengujian
kinerja menunjukkan bahwa penggunaan tungku untuk arang kayu memiliki laju pembakaran yang konstan 8.8 g/menit dan kualitas nyala api tungku ini cukup baik secara visual. Hasil perhitungan menunjukkan
bahwa model yang diterapkan telah dapat memprediksi konsentrasi gas-gas produk yang mencakup CO, CH4, CO2, O2 serta gas N2 dan gas-gas lainnya. Hasil simulasi menunjukkan bahwa tinggi tungku yang lebih rendah (0.5 dan 0.4 m) memberikan konsentrasi gas-gas mampu bakar yang lebih tinggi sedemikian hingga dengan laju konsumsi arang yang sama daya gas potensialnya meningkat dari 2.33 kW pada tinggi
0.6 m menjadi 2.63 kW pada tinggi 0.4 m.


Keywords


NDG stove, charcoal, gasification, modeling

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