Penyusunan model dan simulasi pembentukan besi karbid dan karbon bebas pada zona pendidingan reaktor HYLSA
Abstract
Modeling and simulation of iron carbide and carbon-free formation in cooling zone of reactor HYLSA
The sponge iron production rate increasing in iron ore reduction plant through the nsmg reduction gas temperature will cause more cooling gas flow rate. The objective of this research is to study the effect of cooling gas flow rate on iron carbide and carbon deposit formation through mathematical modelling arrangement and simulation on cooling zone of sponge iron reactor. The modeling is carried out by applying kinetics model. The equations were solved by finite element method. From this study, it was found that the decrease of methane concentration due to iron carbide and free carbon formation occurs when solid temperature reaches 448 oC and 505 oC, respectively. In addition, simulation results show that the cooling gas flow rate above 76000 NCMH is not profitable. On constant methane concentration, the rate of Fe3C and free carbon formation decrease with increasing cooling gas flow rate. However, increasing cooling gas flow rate on make-up gas concentration 95% will decrease total carbon formation. On constant cooling gas flow rate, the rate of Fe3C and free carbon formation increased proportionally with methane concentration.
Keywords: Kinetics Simulation, Sponge Iron Reactor, Methane Decomposition, Iron Carbided
Abstrak
Peningkatan kapasitas produksi besi span pada pabrik reduksi bijih besi melalui peningkatan temperatur gas pereduksi akan berakibat pada tingginya laju alir gas pendingin yang dibutuhkan. Penelitian ini bertujuan untuk melihat pengaruh laju gas pendingin terhadap pembentukan besi karbida dan total karbon pada besi span melalui penyusunan dan simulasi model matematika pada zona pendingin besi span. Pemodelan matematika dilakukan melalui penyusunan model berbasis kinetika dan diselesaikan secara numerik dengan menggunakan metode penghampiran selisih terhingga. Dari hasil penelitian didapatkan bahwa konsentrasi CH<sub>4</sub> menurun akibat adanya pembentukan Fe3C dan dekomposisi met an masing-masing ketika temperatur padatan mencapai 449 oC dan 505 oC. Peningkatan laju alir gas pendingin sampai di alas 76000 NCMH pada kondisi perhitungan tidak akan menguntungkan karena temperatur produk tidak akan dapat mencapai nilai yang lebih rendah lagi. Selain itu, semakin tinggi laju alir gas pendingin, pada konsentrasi gas make-up yang dipertahankan sama dengan umpan, jumlah total karbon semakin sedikit. Sedangkan peningkatan laju alir gas pending in dengan konsentrasi gas make-up sebesar 95% akan meningkatkan jumlah total karbon. Peningkatan konsentrasi CH4 pada laju alir gas pendingin yang tetap, akan meningkatkanjumlah total karbon yang terbentuk.
Kata Kunci: Simulasi Berbasis Kinetika, Reaktor Besi Spon, Dekomposisi Metan, Pembentukan Besi Karbid
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DOI: http://dx.doi.org/10.5614/jtki.2006.5.3.5
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