Prasetiyo, Bima Elang and Prof. Dr.Eng. Ir. Widya Wijayanti, ST., MT and Prof. Dr.Eng. Mega Nur Sasongko, ST., MT. (2024) Pengaruh Penambahan Excess Air pada CFB Boiler dengan Biomassa Kayu Mahoni Menggunakan COMSOL Multiphysics 5.6. Sarjana thesis, Universitas Brawijaya.
Abstract
Pencemaran udara di Jakarta menjadi masalah serius, dengan kota ini menduduki peringkat kedua untuk polusi udara tertinggi di dunia pada tahun 2023. Penyebab utama polusi ini adalah emisi dari kendaraan bermotor dan limbah pabrik. Kualitas udara yang memburuk berdampak negatif pada kesehatan dan kualitas hidup masyarakat di sekitar. Untuk mengurangi pencemaran ini, diperlukan solusi energi alternatif yang ramah lingkungan, seperti biomassa. Biomassa adalah sumber energi dari bahan organik seperti kayu mahoni, yang banyak tersedia di Indonesia dan memiliki konstituen selulosa, hemiselulosa, dan lignin yang ideal untuk pembakaran bahan bakar. Penelitian ini menggunakan simulasi numerik dengan software COMSOL Multiphysics 5.6 untuk mengevaluasi pengaruh penambahan excess air pada performa CFB boiler yang menggunakan kayu mahoni sebagai bahan bakar. CFB boiler dipilih karena efisiensinya yang tinggi dan emisinya yang rendah. Variasi penambahan excess air yang diuji adalah 15%, 20%, 25%, 50%, 100%, dan 200%. Proses penelitian meliputi pemodelan geometri boiler, penentuan boundary conditions, dan analisis distribusi temperatur, tekanan, kecepatan gas, serta konsentrasi emisi gas buang untuk mengamati bagaimana penambahan udara berlebih mempengaruhi efisiensi dan emisi pembakaran. Hasil penelitian menunjukkan bahwa penambahan excess air meningkatkan tekanan dan temperatur di dalam boiler, namun menurunkan efisiensi karena panas lebih cepat terbuang. Pada menit-menit awal simulasi, temperatur tertinggi berada di bagian bawah furnace yang dekat dengan burner, namun seiring waktu dan penambahan excess air, distribusi panas cenderung merata dan menurun. Distribusi kecepatan gas pembakaran menurun dengan peningkatan excess air, akibat tekanan yang lebih tinggi menekan aliran gas keluar. Tekanan tertinggi tercatat pada bagian outlet, menunjukkan akumulasi gas dan tekanan saat keluar dari boiler. Analisis emisi gas buang menemukan bahwa penambahan excess air mengurangi konsentrasi CO2 dan H2O, meningkatkan konsentrasi N2, dan berpotensi meningkatkan pembentukan NOx pada tingkat excess air yang tinggi. Meski pembakaran lebih sempurna dengan penambahan excess air, efisiensi secara keseluruhan menurun karena panas terbuang lebih cepat.
English Abstract
Jakarta faces a severe air pollution issue, as it holds the second position globally for the worst levels of air pollution in 2023. The primary factors contributing to this pollution are the discharge of pollutants from motor vehicles and the disposal of garbage from factories. Declining air quality adversely affects the well-being and overall quality of life of nearby communities. In order to mitigate this pollution, it is imperative to implement ecologically sustainable alternative energy alternatives, such as biomass. Biomass is derived from organic resources, such as mahogany wood, which is abundant in Indonesia. It contains cellulose, hemicellulose, and lignin components that are well-suited for combustion as fuel. This study used numerical simulations using COMSOL Multiphysics 5.6 software to assess the impact of introducing surplus water on the efficiency of CFB boilers fueled by mahogany wood. CFB boilers are selected for their exceptional efficiency and little emissions. The investigated changes in extra water addition included percentages of 15%, 20%, 25%, 50%, 100%, and 200%. The study procedure involves creating a model of the boiler's shape, establishing the limits of its circumstances, and examining the patterns of temperature, pressure, gas velocity, and flue gas emission concentration. The aim is to examine the impact of introducing extra air on the efficiency of combustion and the release of pollutants. The research findings indicate that the addition of excessive water leads to an elevation in both pressure and temperature within the boiler. However, this increase in water content ultimately diminishes efficiency due to the accelerated dissipation of heat. During the first stages of the simulation, the furnace exhibits the maximum temperature near the burner, namely at the bottom. However, as time progresses and an excessive amount of air is introduced, the distribution of heat tends to equalize and diminish. The velocity distribution of the combustion gas reduces as the extra air increases because the increased pressure inhibits the gas from flowing out. The maximum pressure was measured at the outflow, illustrating the buildup of gas and pressure as it exits the boiler. The examination of exhaust emissions revealed that the introduction of surplus air diminishes the levels of CO2 and H2O, amplifies the levels of N2, and has the capacity to enhance the creation of NOx at elevated levels of surplus air. Despite the fact that combustion becomes more thorough with the inclusion of surplus air, the total efficiency diminishes due to the accelerated dissipation of heat.
| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | 0524070128 |
| Uncontrolled Keywords: | Excess Air, CFB Boiler, COMSOL Multiphysics, Biomassa, Kayu Mahoni, Pembakaran |
| Divisions: | Fakultas Teknik > Teknik Mesin |
| Depositing User: | Unnamed user with username nova |
| Date Deposited: | 16 Aug 2024 05:42 |
| Last Modified: | 16 Aug 2024 05:42 |
| URI: | http://repository.ub.ac.id/id/eprint/223279 |
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