Analisis Overheating Pada High Pressure Steam Superheat Coil Pada Convection Section Primary Reformer Di Industri Pupuk

Junius, Richard (2026) Analisis Overheating Pada High Pressure Steam Superheat Coil Pada Convection Section Primary Reformer Di Industri Pupuk. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Primary Reformer merupakan unit utama dalam proses produksi amonia di industri petrokimia, di mana kinerja heat recovery system sangat memengaruhi kestabilan operasi dan efisiensi energi. Pada unit ini, High Pressure Steam Superheater Coil yang berada di Convection Section berfungsi sebagai media perpindahan panas antara fluida panas berupa flue gas dari Radiant Section dan fluida dingin berupa high pressure steam. Pada kondisi operasi tertentu, distribusi aliran flue gas di Convection Section tidak berlangsung secara merata, melainkan mengalami pemusatan aliran (flow maldistribution) dan pembentukan struktur aliran kompleks di sekitar konfigurasi superheater coil, sehingga menyebabkan ketidakseimbangan perpindahan panas, peningkatan heat flux lokal, dan memicu terjadinya overheating pada permukaan tube. Fenomena ini dianalisis menggunakan simulasi numerik tiga dimensi berbasis Computational Fluid Dynamics (CFD) dengan perangkat lunak ANSYS Fluent melalui pendekatan hybrid modeling, di mana sepuluh tube High Pressure Steam Superheater Coil dimodelkan secara eksplisit untuk menangkap distribusi temperatur dan heat flux lokal, sementara susunan tube lainnya direpresentasikan sebagai porous medium untuk memodelkan resistansi aliran dan penyerapan panas secara global. Sumber panas dalam simulasi berasal dari flue gas keluaran Radiant Section serta tambahan panas dari dua belas burner pada bagian atas Convection Section. Hasil simulasi menunjukkan bahwa flow maldistribution menyebabkan terbentuknya zona aliran berkecepatan tinggi, vortex persisten, serta hotspot lokal dengan temperatur maksimum mencapai sekitar 1160 K, yang berimplikasi pada peningkatan heat flux dan percepatan degradasi material tube. Evaluasi termomekanik dan metalurgi menunjukkan bahwa meskipun tegangan operasi masih berada di bawah batas luluh material SA-335 Gr. P91, kondisi temperatur tinggi yang berlangsung terus-menerus menempatkan tube pada zona kritis terhadap kegagalan jangka panjang berbasis creep, serta meningkatkan potensi penipisan dinding akibat Flow Accelerated Corrosion (FAC) dan Flow Induced Erosion (FIE) yang berkontribusi terhadap terjadinya kegagalan tipe fish mouth rupture. Studi ini memberikan dasar kuantitatif untuk evaluasi kinerja termal dan mekanisme kegagalan High Pressure Steam Superheater Coil, sekaligus menjadi acuan dalam perbaikan desain dan pengaturan parameter operasi melalui optimasi distribusi aliran, seperti penambahan guide vane dan flow straightener, pada unit Primary Reformer di pabrik amonia.
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The Primary Reformer is a key unit in ammonia production processes in the petrochemical industry, where the performance of the heat recovery system strongly affects operational stability and energy efficiency. In this unit, the High Pressure Steam Superheater Coil located in the Convection Section functions as a heat transfer medium between the hot fluid in the form of flue gas from the Radiant Section and the cold fluid in the form of high pressure steam. Under certain operating conditions, the distribution of flue gas flow within the Convection Section becomes non-uniform and exhibits flow maldistribution, accompanied by the formation of complex flow structures around the superheater coil configuration, leading to heat transfer imbalance, increased local heat flux, and the occurrence of localized overheating on the tube surface. This phenomenon was investigated using three-dimensional numerical simulations based on Computational Fluid Dynamics (CFD) employing ANSYS Fluent with a hybrid modeling approach, in which ten High Pressure Steam Superheater tubes were modeled explicitly to capture local temperature and heat flux distributions, while the remaining tube banks were represented as a porous medium to account for global flow resistance and heat absorption. The heat source in the simulation originated from flue gas exiting the Radiant Section and additional heat supplied by twelve burners located at the upper part of the Convection Section. The simulation results reveal that flow maldistribution induces high-velocity flow zones, persistent vortices, and localized hotspots with maximum temperatures reaching approximately 1160 K, resulting in elevated local heat flux and accelerated tube material degradation. Thermomechanical and metallurgical evaluations indicate that although the operating stress remains below the yield strength of SA-335 Gr. P91 material, sustained high-temperature exposure places the tube in a critical regime for long-term creep failure, while also increasing the susceptibility to wall thinning due to Flow Accelerated Corrosion (FAC) and Flow Induced Erosion (FIE), which collectively contribute to fish mouth rupture failure. This study provides a quantitative basis for thermal performance evaluation and failure mechanism assessment of the High Pressure Steam Superheater Coil, and serves as a reference for design improvement and operational optimization through flow distribution control measures such as the installation of guide vanes and flow straighteners in the Primary Reformer Convection Section.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Overheating, Flow Maldistribution, High Pressure Steam Superheater Coil, Primary Reformer, Convection Section, CFD, Creep, FAC, Flow Induced Erosion
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Richard j Junius
Date Deposited:	03 Feb 2026 10:13
Last Modified:	03 Feb 2026 10:13
URI:	http://repository.its.ac.id/id/eprint/131904

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