ANALYSIS OF THE EFFECTS OF FEEDING METHODS TO GASIFICATION AND METHANOL SYNTHESIS PERFORMANCE USING ASPEN PLUS

• Main Author: Hermawan Yuwono, Robby
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67981
• Institution: Institut Teknologi Bandung

Methanol is most used chemical in chemical industries, either as mid or final products. Demand CAGR of methanol is growing by 4.5% each year. Methanol can be synthesized from coal syngas. Even though Indonesia has abundant resource of coal, it cannot fill the lack of methanol from conversion of coal-to-methanol (CTM). During year 2020, Indonesia’s import of methanol reaches 840 kilotons. CTM process consist of coal gasification, syngas treatment, and methanol synthesis. Entrained flow gasifier (EFG) is chosen as gasification reactor model, as it produces highest cold gas efficiency (CGE) and carbon conversion (CC). EFG feeding method, slurry feeding, create higher H2-to-CO ratio in syngas compared to dry feeding. However, syngas from gasification has H2-to-CO ratio lower than 1.0, whereas methanol requirement is approaching 2.0. To reach the required value, syngas treatment process is need, and in order to prevent over conversion of H2, syngas is fractionized into two streams. Bypass fraction value decides how much syngas is processed through syngas treatment. Mix of bypass and processed syngas becomes methanol feed. This research will be discussing syngas and liquid methanol characteristics under respective processes to determine each process performance. Aspen Plus helps the CTM process calculation. Development for dry feeding model is based on Shell technology provided by NETL report, 2014, while slurry feeding model use Randall research as base model, with GE-Texaco model, wherein operating parameters are reiterated to get deviation ?10% compared to the references. Validated model is used for gasification and methanol synthesis sensitivity analysis. Variation of gasification agents’ load, equivalence ratio (ER) and steam-to-ratio (STR) is done for gasification process. For methanol synthesis, H2-to-CO ratio of syngas, reactors’ temperature, and process pressure are varied. These variations are done to get CTM optimum conditions using Indonesian coal. Observing gasification process, dry feeding produces 40% lower H2-to-CO ratio, 12% lower consumption of oxidants, and 5% rise in CGE in hot syngas. Optimum value for ER and STR in dry feeding are 0.35 and 0.05; whilst 0.41 and 0.35 are ER and STR in slurry feeding respectively. Shifting to methanol synthesis process, bypass fraction for dry and slurry feeding are 26% and 52% to get near 2.0 H2-to- CO ratio. Highest methanol-to-coal yield is produced from 2.01 ratio, where highest grade comes from 1.0 (dry) and 1.7 (slurry) ratios. Optimal conditions which are obtained, first reactor temperature is 266? and under loop pressure of 43 bars.