Pardede, Anggi Raymond Octorius (2016) Analisis Penggantian Pre-Cooler Untuk Turbin Gas (Studi Kasus Pada PLTG 3 Alstom di PT PT. PLN (Persero) Sektor Keramasan , Palembang, Sumatera Selatan). Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pre-cooler merupakan salah satu komponen alat penukar
kalor yang penting dalam sistem pembangkit listrik tenaga gas.
Seperti prinsip alat penukar kalor pada umumnya, pre-cooler
berfungsi untuk menurunkan temperatur udara dari Compressor
Discharge Pressure (CDP). Udara tersebut akan dimanfaatkan
sebagai pengabut bahan bakar dan pendingin fuel nozzle.
Atomisasi bahan bakar berfungsi untuk menghasilkan proses
pembakaran yang bagus, sedangkan pendinginan fuel nozzle
diperlukan agar nozzle tidak mengalami kerusakan sehingga
nozzle memiliki waktu operasi yang lama. Pada pola operasi yang
kontinu, pre-cooler memiliki modus kegagalan yaitu mengalami
kebocoran yang diakibatkan pengikisan oleh fluida kerja dan
getaran yang berlebih. Ketidakefisien suatu alat dapat
menyebabkan kerugian energi yang besar, seperti biaya produksi
meningkat dan menurunnya kualitas produksi. Oleh karena itu,
perlu dilakukan redesign pre-cooler agar tidak terjadi penurunan
performa.
Pada penelitian tugas akhir ini, penggantian pre-cooler
dilakukan dengan merancang ulang pre-cooler dengan 3 jenis heat
exchanger, yaitu shell-and-tube, plate-fin, dan circular finned
tube. Redesign dilakukan dengan analisis perpindahan panas.
Variabel yang divariasikan adalah geometri masing-masing tipe pre-cooler. Pitch ratio dan baffle spacing digunakan sebagai
variasi geometri untuk shell-and-tube, sedangkan circular finned
tube menggunakan variasi surface designation yang diambil dari
buku M. Kays dan W. London. Batasan atau constraint yang
ditentukan untuk pre-cooler tipe compact adalah volume ruang
penempatan pre-cooler. Metode yang digunakan dalam
perancangan adalah metode NTU dan LMTD yang meliputi
perhitungan perpindahan panas untuk fluida sisi eksternal dan
internal, perhitungan area perpindahan panas, heat transfer actual,
overall heat transfer coefficient, dan efektivitas.
Berdasarkan hasil penelitian, didapatkan bahwa pada
existing pre-cooler, nilai efektivitas sebesar 0.592 dan number of
transfer unit sebesar 1.01. Desain optimum hasil rancangan precooler dengan tipe shell and tube terdapat pada variasi pitch ratio
1.25 dan baffle spacing 0.2 IDshell . Sedangkan desain optimum
tipe circular finned tube terdapat pada konfigurasi CF-8.7-
5/8J(a). Berdasarkan komparasi kedua tipe, circular finned tube
memiliki kemampuan perpindahan panas yang lebih baik
dibandingkan dengan shell and tube. Hal tersebut ditunjukkan
melalui efektivitas circular finned tube sebesar 0.7, sedangkan
shell and tube memiliki efektivitas 0.63.
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Pre-cooler is a heat exchanger device in the gas turbine
power plant that used to lowering the temperature of discharge air
from the compressor. Cooled air will be used to atomise the fuel
in a combustor as well as a coolant for fuel nozzle. The
atomization process aims to produce a better fuel firing quality,
whereas the cooling process of fuel nozzle intended to maintain
the nozzle from breakdown as a result of protracted operational
time. Insufficiency of an installation could cause a system failure
It is, therefore, one of the means to prevent the degradation of
performance of the device, pre-cooler needed to be replaced in
such a way and analysed thoroughly.
In this research, replacement of pre-cooler is done by
redesigning into three kinds of heat exchangers, which are shell
and tube and circular finned tube. In designing the pre-cooler for
shell and tube type, baffle spacing and pitch diameter are the
discrete variables. Whilst, for the circular finned tube type, is
varied by its surface designations. The analysis that used in this
research uses heat transfer analysis through LMTD and NTU
method. Each type of heat exchangers varied by its surface
designations. These methods are used to obtain heat transfer for
both of the fluids, heat transfer areas, overall heat transfer coefficient, and effectiveness. Furthermore, in this research,
pressure drops is also being analyzed for both of the types.
From the research regarding existing pre-cooler, through
NTU method analysis, the effectiveness of its pre-cooler is of
0.592 and Number of Transfer Unit is of 1.01. The optimum
design from the new design pre-cooler with shell and tube type is
obtained at variation of pitch ratio of 1.25 and baffle spacing of
0.2 IDshell. Meanwhile, the optimum design for circular finned
tube is at configuration of CF-8.7-5/8J(a). Based on the results of
the comparison of both pre-cooler, circular finned tube has a
better quality in heat transfer. It can be shown by its effectiveness
value of 0.7, whilst the shell and tube has 0.63 of its
effectiveness.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Additional Information: | RSM 621.165 Par a |
| Uncontrolled Keywords: | Pre-cooler; re-design; LMTD; NTU; shell an tube heat exchanger; circular finned tube heat exchanger effectiveness |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ778 Gas turbines |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | ansi aflacha |
| Date Deposited: | 30 Jun 2020 03:16 |
| Last Modified: | 30 Jun 2020 03:16 |
| URI: | http://repository.its.ac.id/id/eprint/76256 |
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