STUDI TEKNO-EKONOMI PEMURNIAN BIOGAS DARI LIMBAH DOMESTIK - Wahyu Pamungkasjati, Akhwari (2012)
INTISARI Pemurnian biogas dari limbah domestik bertujuan meningkatkan nilai kalori pembakaran dan mencegah korosi. Biogas dengan komposisi gas 95% CH4 (biometan) dapat dimanfaatkan lebih lanjut yang salah satunya sebagai pengganti gas alam kualitas pipeline. Penelitian ini bertujuan mempelajari kelayakan secara teknis dan ekonomi metode pemurnian biogas menggunakan water scrubbing, monoethanol amin, diethanol amin, pressure swing adsorption dan cryogenic separation serta mempelajari nilai production cost dan kapasitas scale-up untuk menentukan kapasitas minimum metode pemurnian biogas yang ekonomis. Penelitian ini menggunakan data sekunder dari pilot plant Biogas Pasar Induk Buah dan Sayuran Gemah Ripah, Gamping, Sleman, Yogyakarta. Penelitian dilakukan dengan mensimulasikan pemurnian biogas menggunakan software simulasi Aspen Plus sehingga diperoleh neraca massa, panas dan dimensi alat yang dibutuhkan. Variabel yang dipelajari adalah nilai production cost dan kapasitas scale-up untuk tiap metode pemurnian biogas. Sensitivity analysis yang dilakukan adalah variasi perubahan komposisi gas 30-70 % CH4 dalam biogas terhadap nilai Perbandingan Laju Solven (L, m3/jam) terhadap Laju Biogas (G, m3/jam), L/G pada menara absorber serta perubahan dari penurunan 100 % sampai dengan kenaikan 100 % harga limbah terhadap nilai production cost dan perubahan finances 0-15 % terhadap nilai production cost. Kriteria ekonomis penelitian ini adalah nilai production cost proses pemurnian biogas yang sudah mendekati harga gas alam dengan kualitas pipeline. Hasil yang diperoleh dari penelitian ini secara teknis kemurnian biogas yang dihasilkan hingga kemurnian 95 % CH4 sehingga bisa digunakan sebagai pengganti gas alam kualitas pipeline dan secara ekonomi pemurnian biogas yang paling murah adalah menggunakan water scrubber yang dilihat dari perbandingan harga Fixed capital Investment, Total Capital Invesment dan Production Cost. Scale up yang dilakukan menghasilkan kapasitas minimum pemurnian biogas yang ekonomis adalah kapasitas 100 ton limbah domestik/hari dengan nilai production cost yang lebih rendah jika dibandingkan dengan harga gas alam kualitas pipeline yang berkisar antara 6-10 US$/MMBtu. Sensitivity analysis dari variasi komposisi gas 30-70 % CH4 menghasilkan perubahan nilai L/G pada menara absorber berkisar antara 0,005-0,025; variasi harga limbah dari penurunan 100% sampai dengan kenaikan 100% menghasilkan perubahan nilai production cost antara 3-8 US$/MMBtu; variasi perubahan finances 0-15 % menghasilkan perubahan nilai production cost antara 2-14 US$/MMBtu. Kata kunci : pemurnian biogas, limbah domestik, tekno-ekonomi, biometan x ABSTRACT Domestic waste biogas purification can increase the caloric value of combustion and prevent corrosion. Biogas with 95 % of methane can be used to substitute pipeline quality natural gas. The objective of this research was to study technical and economical feasibility of biogas purification methods using water scrubbing, reactive absorption using mono and di-ethanol amine, pressure swing adsorption, and cryogenic separation. This research also aimed to estimate gas production costs obtained from various purification methods and determine their minimum economical scale up capacities. This research used the secondary data from pilot plant of Biogas of Pasar Induk Buah dan Sayuran Gemah Ripah, Gamping, Sleman, Yogyakarta. This research was done by simulated the biogas purification by using simulation software Aspen Plus to obtain the mass and energy balance, and equipment specification needed. Variables studied were the influences of production cost and scale up capacities for each biogas purification method. The sensitivity analysis was done to study the influence of gas composition ranged at 30-70% CH4 in biogas toward the flow rate of absorbent (L, m3/hour) to flow rate of gas (G, m3/hour) ratio in the absorber column, the price of waste changed from decreasing 100% up to increasing 100% toward the production cost and the finance changed ranged at 0-15% toward the production cost. The criterion of economical in this research was the production cost of biogas purification which close to the price of pipeline quality natural gas. The result obtained from this research was reviewed from technical and economical feasibility. Technically the biogas with 95 % CH4 can be used to substitute pipeline quality natural gas, it was found that all methods were feasible. Economically the Fixed Capital Investment, Total Capital Investment and Production Cost were compared for all methods, it was found that water scrubber was the cheapest. The production cost of scale up capacities compared to the price of pipeline quality natural gas which ranged at 6-10 US$/MMBtu so that the minimum capacity of economical biogas purification methods was 100 tons waste/day. The influence of gas composition ranged at 30-70% of CH4 produced the L/G value change in the absorber column ranged at 0,005-0,025; the influence of waste price from decreasing 100% up to increasing 100% produced the production cost change ranged at 3-8 US$/MMBtu and the influence of finances from 0-15% produced the production cost change ranged at 2-14 US$/MMBtu. Keywords: biogas purification, domestic waste, techno-economic, bio-methane.