Pemodelan dan Analisis Pengaruh Kenaikan Putaran Kerja Terhadap Respon Dinamis, Kasus Unbalance Rotor Steam Turbine Unit 1 PLTU Amurang 2x25MW

Mahartana, Ida Bagus Putu Putra (2017) Pemodelan dan Analisis Pengaruh Kenaikan Putaran Kerja Terhadap Respon Dinamis, Kasus Unbalance Rotor Steam Turbine Unit 1 PLTU Amurang 2x25MW. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Unbalance merupakan salah satu kasus penyebab terjadinya getaran tinggi pada rotating machinery yang linier terhadap peningkatan putaran pada mesin. Efek unbalance dapat diminimalisir dengan menambahkan correction weight sehingga membangkitkan gaya sentrifugal baru yang berlawanan arah dengan initial unbalance sistem, sehingga jumlah gaya dan momen yang bekerja pada sistem akan saling mengurangi dan akan menurunkan level vibrasi sampai level yang aman. Dalam tugas akhir ini dilakukan pemodelan dan simulasi unbalance dan balancing rotor untuk melihat efek kenaikan putaran kerja terhadap respon dinamisnya. Seluruh parameter digunakan diperoleh dari data maintenance Unit 1 PLTU AMURANG UBJOM PJBS 2x25MW pada tanggal 28 November 2014. Rotor dimodelkan seperti disk dengan jari-jari 420 mm dan 480mm, dimana rotor terpasang pada fleksibel poros yang ditumpu 2 buah rigid bearing. Dari data, diperoleh nilai initial unbalance sebesar 0.286 kg pada bidang 1 dengan posisi angular pada 139.30dan 1.14 kg pada bidang 2 dengan posisi angular 237.80. Rotor di low-balancing dengan correction weight sebesar 9.57 gr pada posisi angular 152,40 dibidang 1 dan 18.2 gr pada posisi angular 168.70 dibidang 2. Pada tahap simulasi balance rotor, nilai correction weight diambil dari data hasil low-balancing dan hasil perhitungan dari balancing teoritis. Dari kondisi unbalance, didapatkan hasil bahwa kenaikan level vibrasi pada rotor linier terhadap kenaikan pembebanan putaran hingga mencapai frekuensi resonansinya dan respon vibrasi menurun saat rotor telah melewati fase putaran kritis lalu stabil pada frekuensi operating speed maksimum. Balancing teoritis yang dilakukan dalam penelitian ini menghitung seluruh momen yang berkerja pada masing-masing bidang pembalance, sehingga diperoleh nilai correction weight yang baru. Hasil balancing rotor menunjukkan bahwa metode low-balancing masih menimbulkan vibrasi tinggi pada rotor, terlihat dari seluruh respon yang diperoleh dari hasil simulasi. Setelah dibalancing secara teoritis, hasil balancing menunjukkan penurunan amplitudo getaran sebesar 10 % dari kondisi initial unbalance. ======================================================================================== Unbalance is one of the causes of the occurrence high vibration in a rotating machinery, which is linear with the increasement of the machine’s operating speed. Unbalance effect can be minimalized by installing a correction weight, so it can generate a new centrifugal force which is reversing the initial unbalance system, so the amount of force and moment that work in the system will reduce each other and reduce the vibration level to the safe level as well. In this final assignment, a modeling and simulation of unbalance and balancing rotor was made to observe the increasing effect of operating speed to the dynamic response. All of the parameters are obtained from maintenance data Unit 1 PLTU Amurang UBJOM PJBS 2x25MW on November 28th, 2014. The rotor was modeled by a disk with 420 mm and 480 mm radius, where the rotor is attached to the flexible shaft with 2 rigid bearings attached on each side. From the data, the value of initial unbalance has known as 0.286 kg at 139.30 on plane 1 and 1.14 kg at 237.80 on plane 2. The rotor was added with 9.57 gr correction weight at 152. 40 on plane 1 and 18.2 gr correction weight at 168.70 on plane 2. In this rotor balance simulation process, the value of correction weight taken from the result of low balancing data and the result of theoretical balancing calculation. The result from the unbalance condition are the increasing of the vibration level of the rotor is linear to the increasing of operating speed until it reached the resonance frequency and the vibration response has reduced when the rotor passed through the critical speed phase and then stable at the maximum operating speed frequency. The theoretical balancing in this research was done by calculating all the moment work in each plane, therefore the new counterweight value has gained. The balancing result shown that vibration levels after the low-balancing method still produce high vibration on the rotor, as shown by the result of the simulation. After balanced with theoritical method, the balancing result shown that the amplitude is decreased by 10 % from the initial unbalance.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: initial unbalance; low-balancing; balancing teoritis; model rotor; theoritical balancing; Rotor model.
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction
Divisions: Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User: IDABAGUS PUTU PUTRA MAHARTANA
Date Deposited: 16 Mar 2017 03:02
Last Modified: 05 Mar 2019 01:51
URI: http://repository.its.ac.id/id/eprint/2148

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