Kajian Numerik Pengaruh Variasi Biodiesel dan Energi Input HESI terhadap Penyalaan dan Emisi Boiler PC PLTU

Syakuro, Muhammad Aji Abdan (2026) Kajian Numerik Pengaruh Variasi Biodiesel dan Energi Input HESI terhadap Penyalaan dan Emisi Boiler PC PLTU. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pemerintah Indonesia menetapkan mandatori biodiesel B50 berlaku mulai 1 Juli 2026, sementara PLTU Suralaya baru mengoperasikan B40 pada burner minyak untuk penyalaan awal (start-up) boiler Pulverized Coal (PC) sejak awal 2025 dan telah mengalami ignition delay panjang hingga kegagalan penyalaan pada kondisi cold start. Secara termofisik dan kinetika reaksi, biodiesel memiliki viskositas lebih tinggi, volatilitas lebih rendah, dan energi aktivasi oksidasi lebih besar dibandingkan solar, sehingga ignition delay memanjang dan peluang terbentuknya flame kernel stabil menurun pada sistem High Energy Spark Ignition (HESI) yang bersifat sangat transient. Penelitian ini menganalisis proses penyalaan awal pada 18 kasus simulasi CFD yang mencakup delapan variasi biodiesel (B0, B30, B35, B40, B50, B60, B70, dan B80) pada tiga tingkat heat generation (2, 4, dan 8 J). Pada heat generation 2 J, ignition delay meningkat monoton dan kuat terhadap kadar biodiesel, dari 0,037 s (B0) hingga 0,113 s (B60) dengan koefisien korelasi r = +0,92; peningkatan ini bersumber murni dari physical delay karena model reaksi yang digunakan bersifat mixing-limited sehingga tidak mengandung kinetika kimia yang membedakan antar-blend. Temuan utama penelitian ini adalah bahwa energi spark HESI eksisting 2 J tidak mencapai penyalaan terverifikasi pada biodiesel B70 dan B80 dalam durasi simulasi (0,3 s), menandai keberadaan ambang energi penyalaan di antara B60 dan B70; kedua blend baru berhasil menyala pada 4 J. Peningkatan heat generation mempersingkat ignition delay sekaligus memulihkan kemampuan penyalaan biodiesel kadar tinggi; pada karakter nyala mandiri, netralitas emisi NOx terhadap heat generation terverifikasi pada rentang B40–B60, sedangkan pada B70 dan B80 responsnya tidak lagi monoton, sehingga keputusan upgrade menjadi persoalan keekonomian dan keandalan penyalaan, bukan dilema teknis antara keandalan dan emisi. Tinjauan investasi pelengkap menunjukkan Capex retrofit HESI Rp 1,62 miliar dengan payback period 1,7–9,1 tahun. Kesiapan PLTU Suralaya menghadapi mandatori biodiesel memerlukan penguatan energi penyalaan HESI untuk menjamin keandalan penyalaan biodiesel kadar tinggi.
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Biodiesel cofiring is a key strategy for power-sector decarbonization. PLTU Suralaya has operated B40 biodiesel on oil burners as the start-up ignition system for Pulverized Coal (PC) boilers since early 2025, but has encountered prolonged ignition delay and repeated ignition failures under cold start conditions. Biodiesel's higher viscosity, lower volatility, and greater oxidation activation energy compared to diesel prolong ignition delay and reduce the likelihood of stable flame kernel formation within the highly transient High Energy Spark Ignition (HESI) system. This study analyzes the initial ignition process across 18 simulation cases covering eight biodiesel blends (B0, B30, B35, B40, B50, B60, B70, and B80) at three heat generation levels (2, 4, and 8 J) using a Computational Fluid Dynamics (CFD) approach. At 2 J, ignition delay increases strongly and monotonically with biodiesel content, from 0.037 s (B0) to 0.113 s (B60) with a correlation coefficient r = +0.92; this increase stems purely from physical delay, since the reaction model used is mixing-limited and contains no chemical kinetics that would differentiate between blends. The principal finding is that the existing HESI spark energy (2 J) does not reach verified ignition for B70 and B80 within the simulated duration (0.3 s), marking an ignition-energy threshold between B60 and B70; both blends ignite only at 4 J. Increasing heat generation shortens ignition delay and restores the ignitability of high blends; under self-sustained flame conditions, NOx neutrality across heat generation levels is confirmed for B40–B60, while B70 and B80 show a non-monotonic response, making the upgrade decision an economic and reliability question rather than a technical dilemma between reliability and emissions. A supplementary review estimates the HESI retrofit Capex at IDR 1.62 billion, with payback ranging 1.7–9.1 years. Overall, readiness for the biodiesel mandate requires strengthening HESI ignition energy to ensure reliable ignition of high-content blends.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Cofiring biodiesel; High Energy Spark Ignition (HESI); Ignition delay; Penyalaan awal boiler Biodiesel cofiring; Boiler start-up ignition; High Energy Spark Ignition (HESI); Ignition delay
Subjects:	Q Science T Technology > TJ Mechanical engineering and machinery T Technology > TJ Mechanical engineering and machinery > TJ324.5 Fuel systems
Divisions:	Faculty of Industrial Technology > Mechanical Engineering > 21101-(S2) Master Thesis
Depositing User:	Muhammad Aji Abdan Syakuro
Date Deposited:	31 Jul 2026 00:13
Last Modified:	31 Jul 2026 00:13
URI:	http://repository.its.ac.id/id/eprint/139702

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