Analisis Numerik Pengaruh Off Service Hph 6 Terhadap Temperatur Metal Pipa Reheater Serta Performa Plant

Amarta, Valiant Tirta (2022) Analisis Numerik Pengaruh Off Service Hph 6 Terhadap Temperatur Metal Pipa Reheater Serta Performa Plant. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Permasalahan yang sering dihadapi pada PLTU adalah kebocoran pada high pressure heater (HPH) sehingga perlu dilakukan bypass. Bypass memiliki dampak terhadap ekstraksi massa pada HPH selanjutnya yang menjadi meningkat karena bebannya bertambah. Penambahan ekstraksi massa dapat menjadi masalah apabila terjadi pada HP turbin karena akan mengurangi laju massa steam pada reheater yang dapat menyebabkan peningkatan temperatur metal tube dan menyebabkan terjadinya overheat. Temperatur metal pipa dapat dikontrol oleh desuperheater. Adapun dampak negatif dari adanya desuperheater yaitu peningkatan heat rate dan penurunan kerja turbin. Hal tersebut terjadi karena feedwater yang diubah menjadi uap dan masuk ke turbin HP berkurang disebabkan oleh feedwater yang diekstraksi sebelum masuk ke HPH. Oleh karena itu, perlu dilakukan analisis pengaruh off service HPH 6 terhadap temperatur metal pipa reheater dan performa plant.
Alur penelitian ini dimulai dari analisis numerik menggunakan software Cycle-Tempo kemudian Fluent. Software Cycle-Tempo digunakan untuk melakukan analisis perubahan ekstraksi massa dan performa plant. Variasi yang dilakukan yaitu tiga kondisi dari pembangkit yaitu, normal, HPH 6 off service dengan menjaga temperatur feedwater yang masuk ke boiler, dan HPH 6 off service temperatur feedwater yang masuk ke boiler mengalami penurunan. Pada software Fluent dilakukan analisis dari temperatur metal pipa. Untuk mempercepat proses komputasi, bagian boiler yang digunakan sebagai domain dimulai dari elevasi 48,53 hingga 71,52 meter. Selain itu, hanya dilakukan pengamatan pada 2 baris pipa dengan 3 buah pipa pada tiap baris. Pada penelitian ini tidak dilakukan permodelan pembakaran, flue gas dimodelkan dengan velocity inlet dan outflow. Material yang digunakan sebagai pipa reheater adalah ASTM A213 T22. Untuk, memodelkan uap dalam pipa, dinding bagian dalam pipa digunakan pengaturan konveksi.
Dari hasil penelitian yang dilakukan, didapatkan hasil bahwa keadaan off service HPH 6 dapat meningkatkan temperatur metal pipa reheater sebesar 2,56% pada bagian luar pipa dan 2,7% pada bagian dalam pipa. Peningkatan temperatur tersebut menyebabkan pipa melebihi batas temperatur operasinya, oleh karena itu temperatul metal pipa harus dijaga. Temperatur metal pipa reheater dapat dijaga dengan dua cara yaitu, desuperheater dan menurunkan temperatur feedwater yang masuk ke boiler. Pada keadaan HPH 6 off service dengan desuperheater, terjadi penurunan kerja turbin sebesar 1,3%, penurunan Qboiler sebesar 0,9%, dan penurunan efisiensi sebesar 0,5%. Pada keadaan HPH 6 off service dengan temperatur feedwater yang masuk ke boiler mengalami penurunan, terjadi peningkatan Qboiler sebesar 4,7%, kerja turbin sebesar 3,6%, dan NPHR sebesar 1%. Sementara itu, efisiensi menurun sebesar 1% dibandingkan dengan kondisi normal.
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The problem that is often faced in power plant is a leak in the
high pressure heater (HPH) so that it needs to be bypassed.
Bypass has an impact on mass extraction in subsequent HPHs
which increases as the load increases. The addition of mass
extraction can be a problem if it occurs in the HP turbine because
it will reduce the mass rate of steam in the reheater which can
cause an increase in the metal tube temperature and cause
overheating. The metal pipe temperature can be controlled by the
desuperheater. The negative impact of the presence of a
desuperheater is an increase in the heat rate and a decrease in
turbine work. This happens because the feedwater that is
converted into steam and enters the HP turbine is reduced due to
the extracted feedwater before entering the HPH. Therefore, it is
necessary to analyze the effect of off service HPH 6 on the metal
temperature of the reheater pipe and plant performance.
The flow of this research starts from numerical analysis using
Cycle-Tempo software and then Fluent. Cycle-Tempo software is
used to analyze changes in mass extraction and plant
performance. The variations carried out are three conditions
from the generator, namely, normal, HPH 6 off service by
maintaining the temperature of the feedwater entering the boiler,
and HPH 6 off service the temperature of the feedwater entering
the boiler has decreased. In Fluent software, an analysis of the
pipe metal temperature is carried out. To speed up the
computational process, the boiler section used as the domain
viii
starts from an elevation of 48.53 to 71.52 meters. In addition,
observations were only made on 2 rows of pipes with 3 pipes in
each row. In this study no combustion modeling was carried out,
flue gas was modeled with inlet and outflow velocity. The material
used as the reheater pipe is ASTM A213 T22. To model the steam
in the pipe, the inner wall of the pipe is used convection settings.
From the results of the research conducted, it was found that
the off service condition of HPH 6 could increase the metal
temperature of the reheater pipe by 2.56% on the outside of the
pipe and 2.7% on the inside of the pipe. The increase in
temperature causes the pipe to exceed its operating temperature
limit, therefore the metal temperature of the pipe must be
maintained. The metal temperature of the reheater pipe can be
maintained in two ways, namely, desuperheater and lowering the
temperature of the feedwater entering the boiler. In the condition
of HPH 6 off service with desuperheater, there is a decrease in
turbine work by 1.3%, a decrease in Qboiler by 0.9%, and a
decrease in efficiency by 0.5%. In the HPH 6 off service condition
with the feedwater temperature entering the boiler decreased,
there was an increase in Qboiler by 4.7%, turbine work by 3.6%,
and NPHR by 1%. Meanwhile, the efficiency decreased by 1%
compared to normal conditions.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	analisis numerik, performa plant, temperatur metal
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Valiant Tirta Amarta
Date Deposited:	08 Feb 2022 03:12
Last Modified:	08 Feb 2022 03:12
URI:	http://repository.its.ac.id/id/eprint/92674

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