Magang Mandiri di PT. Pertamina EP Cepu

Laksana, Ligama Putra (2024) Magang Mandiri di PT. Pertamina EP Cepu. Project Report. [s.n.]. (Unpublished)

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Abstract

Tangki Penyimpanan Kondensat (XXX-XYZ) di fasilitas Gas Processing Facility (GPF) merupakan aset krusial yang beroperasi pada tekanan atmosferik rendah di bawah sistem N2 blanketing. Operasi tangki ini menghadapi tantangan diskrepansi pembacaan tekanan antara sensor BPCS (PT-XYZ) dan SIS (PZT-XYZ), di mana data RTIS menunjukkan offset signifikan 0.05 psi yang menimbulkan risiko false trip dan kerugian produksi, terutama mengingat batas kritis Low-Low (LL) trip pada -0.010 psig. Penelitian ini bertujuan untuk menginvestigasi akar penyebab (root cause) dari diskrepansi tersebut dan merumuskan solusi mitigasi yang efektif melalui pendekatan simulasi multi-platform. Metodologi multi-platform ini meliputi validasi model steady state HYSYS terhadap HMB (eror 0,00%), pengembangan model dinamis yang
divalidasi terhadap data RTIS, dan analisis Computational Fluid Dynamics (CFD) tiga dimensi dengan Ansys Fluent untuk investigasi fisika aliran . Analisis skenario false trip mengonfirmasi bahwa offset ini dapat menyebabkan SIS terpicu secara tidak semestinya, terutama pada kasus Low-Low Pressure. Analisis CFD membuktikan bahwa akar penyebab diskrepansi bukanlah kegagalan instrumen, melainkan fenomena fisika aliran. Simulasi CFD menunjukkan bahwa tapping point sensor BPCS (PT-01) berada di zona aliran stagnan (mendekati 0 m/s), sedangkan tapping point sensor SIS (PZT-XYZ) terletak di nozel vent gas, di mana terjadi akselerasi aliran yang menyebabkan penurunan tekanan statis lokal akibat efek Bernoulli. Berdasarkan temuan ini, direkomendasikan dua solusi: Solusi jangka pendek untuk mitigasi akurasi, yaitu mengganti transmitter SIS (PZT) dengan model yang memiliki rentang (range) lebih sempit (misalnya, -0.05 hingga +0.1 psig) untuk meningkatkan resolusi pengukuran. Solusi jangka panjang yang bersifat permanen, yaitu merelokasi nozel sensor SIS ke "zona tenang" di atap tangki, yang harus direncanakan pada jadwal turnaround pabrik berikutnya.
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The Condensate Storage Tank (XXX-XYZ) at the Gas Processing Facility (GPF) is a crucial asset operating at low atmospheric pressure under an N2 blanketing system. The operation of this tank faces the challenge of pressure reading discrepancies between the BPCS (PT-XYZ) and SIS (PZT-XYZ) sensors, where RTIS data indicates a significant offset of 0.05 psi that poses a risk of false trips and production losses, especially considering the critical Low-Low (LL) trip limit at -0.010 psig. This study aims to investigate the root cause of this discrepancy and formulate effective mitigation solutions through a multi-platform simulation approach. This multi-platform methodology includes the validation of a HYSYS steady-state model against the HMB (0.00% error), the development of a dynamic model validated against RTIS data, and a three-dimensional Computational Fluid Dynamics (CFD) analysis using Ansys Fluent to investigate the flow physics. The false trip scenario analysis confirms that this offset can cause the SIS to trigger inappropriately, particularly in the case of Low-Low Pressure. The CFD analysis proves that the root cause of the discrepancy is not instrument failure, but rather a flow physics phenomenon. The CFD simulation shows that the BPCS sensor tapping point (PT-01) is located in a stagnant flow zone (approaching 0 m/s), while the SIS sensor tapping point (PZT-XYZ) is located at the gas vent nozzle, where flow acceleration occurs, causing a localized static pressure drop due to the Bernoulli effect. Based on these findings, two solutions are recommended: a short-term solution for accuracy mitigation, which involves replacing the SIS transmitter (PZT) with a model that has a narrower range (e.g., -0.05 to +0.1 psig) to improve measurement resolution. A permanent long-term solution, which involves relocating the SIS sensor nozzle to a "quiet zone" on the tank roof, which should be planned for the next plant turnaround schedule.

Item Type:	Monograph (Project Report)
Uncontrolled Keywords:	CFD, HYSYS, Ansys, BPCS, SIS
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics
Divisions:	Faculty of Vocational > 24305-Industrial Chemical Engineering Technology
Depositing User:	Ligama Putra Laksana
Date Deposited:	22 Jul 2026 02:15
Last Modified:	22 Jul 2026 02:15
URI:	http://repository.its.ac.id/id/eprint/136148

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