Analisa Numerik Transien Pengaruh Main Steam Heating Rate & Start-Up Condition Terhadap Equivalent Stress & Material Life Pada Superheater Header

Hidayatulloh, Sultan Achmad (2023) Analisa Numerik Transien Pengaruh Main Steam Heating Rate & Start-Up Condition Terhadap Equivalent Stress & Material Life Pada Superheater Header. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pembangkit listrik terutama Pembangkit Listrik Tenaga Uap (PLTU), dapat dipastikan akan mengalami proses overhaul. Setelah dilakukan proses overhaul akan dilakukan prosedur start-up agar pembangkit dapat memproduksi listrik sesuai dengan permintaan yang ada. Dalam prosedur start-up terdapat suatu proses yang dinamakan start-firing. Proses tersebut bertujuan untuk menaikkan temperatur main steam hingga titik steam dalam temperatur yang siap untuk rolling turbin. Proses start-firing memiliki durasi yang bergantung pada nilai heating rate yang dinyatakan dengan satuan ˚C/min. Semakin besar nilai heating rate maka durasi start-firing akan semakin cepat pula. Namun nilai heating rate juga berbanding lurus dengan equivalent stress pada heating part boiler terutama superheater header yang dapat membatasi nilai heating rate agar equivalent stress yang dihasilkan tidak menyebabkan kegagalan pada superheater header. Hal tersebut melatarbelakangi diperlukannya anaisis terhadap pengaruh heating rate dan kondisi start-up boiler terhadap tegangan yang terjadi pada superheater header. Analisis dilakukan dengan Finite Element Method (FEM) dengan software ANSYS Transient Thermal untuk analisis distribusi temperatur dan ANSYS Static Structural untuk menganalisis equivalent stress yang terjadi pada superheter header. Variasi yang digunakan yaitu nilai heating rate sebesar 1.6 ˚C/min, 2 ˚C/min, dan 2.75 ˚C/min, yang dikombinasikan dengan variasi kondisi start-up yang terdiri dari cold start-up, warm start-up, dan hot start-up. Output dari simulasi adalah kontur distribusi temperatur, kontur equivalent stress, dan umur siklus material superheater header. Melalui hasil simulasi dapat disimpulkan bahwa heating rate dan start-up condition berpengaruh terhadap equivalent stress yang dihasilkan. Semakin tinggi nilai heating rate maka semakin tinggi nilai equivalent sress yang terjadi. Semakin panas start-up condition yang digunakan maka semakin besar juga equivalent stress yang dihasilkan. Apabila equivalent stress melebihi nilai endurance limit material terlemah penyusun superheater header (ASTM A213 T22) maka akan terjadi failure pada cycle tertentu sehingga tidak dapat mencapai kondisi infinite lifetime. Hal tersebut terjadi pada variasi heating rate 2.75˚C/min dengan kondisi warm dan hot start-up.
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Power plants, especially Steam Power Plants (PLTU), can certainly experience an overhaul process. After the overhaul process is carried out, a start-up part-up procedure will be carried out so that the power plant can produce electricity in accordance with demand. In the start-up procedure there is a process called start-firing. The process aims to raise the temperature of the main steam to the point where the steam is at a turbine rolling temperature. The start-firing process has a duration that depends on the heating rate value expressed in ˚C/min. The greater the heating rate has faster duration. However, the heating rate value is also directly proportional to the equivalent stress on the heating part of the boiler, especially the superheater header, which can limit the heating rate value so that the resulting equivalent stress does not cause failure of the superheater header. This is the background for an analysis of the influence of the heating rate and boiler start-up conditions on the stress that occurs in the superheater header. The analysis was carried out using the Finite Element Method (FEM) with ANSYS Transient Thermal software to analyze the temperature distribution and ANSYS Static Structural to analyze the equivalent stress that occurs in the superheater header. The variation used is the heating rate value of 1.6 ˚C/min, 2 ˚C/min and 2.75 ˚C/min combined with a variety of start-up conditions consisting of cold start-up, warm start-up, and hot start-up. The output of the simulation is the temperature distribution contour, equivalent stress contour, and the cycle life of the superheater header material. Through the simulation results it can be concluded that the heating rate and start-up condition affect the resulting equivalent stress. The higher the heating rate, the higher the equivalent stress that occurs. The hotter the start-up condition used, the greater the equivalent stress generated. If the equivalent stress exceeds the endurance limit value of the weakest material making up the superheater header (ASTM A213 T22), a failure will occur in a certain cycle so that it cannot reach an infinite lifetime condition. This occurs at the heating rate variation of 2.75˚C/min with warm and hot start-up conditions

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Superheater, Header, Heating Rate, Start-up, Stress
Subjects:	T Technology > TJ Mechanical engineering and machinery
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Sultan Achmad Hidayatulloh
Date Deposited:	18 Sep 2023 10:14
Last Modified:	18 Sep 2023 10:14
URI:	http://repository.its.ac.id/id/eprint/102874

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