Studi Numerik Pengaruh Susunan Tube Aligned dan Staggered Dengan Variasi Diameter Tube Air Preheater Terhadap Posisi Terjadinya Sulfuric Acid Dew Point

Listijabudhi, Andrew Tirtawijaya (2019) Studi Numerik Pengaruh Susunan Tube Aligned dan Staggered Dengan Variasi Diameter Tube Air Preheater Terhadap Posisi Terjadinya Sulfuric Acid Dew Point. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Air preheater merupakan salah satu komponen dalam boiler untuk memanasi udara pembakaran baik udara primer maupun sekunder agar proses pembakaran batubara dalam boiler terjadi secara optimal. Seringkali desain tube air preheater yang tidak tepat menyebabkan kerusakan di dalam tube air preheater, salah satunya akibat korosi. Korosi dalam air preheater terjadi akibat temperatur flue gas turun hingga di bawah sulfuric acid dew point temperature. Susunan serta dimensi dari tube air preheater dapat mempengaruhi distribusi temperatur flue gas yang mengalir di dalam air preheater sehingga perlu ditinjau berdasarkan sulfuric acid dew point temperature.
Tugas akhir ini menggunakan perangkat lunak GAMBIT 2.4.6 dan FLUENT 18.0 untuk melakukan simulasi susunan tube di dalam air preheater. Susunan tube dibuat secara aligned dan staggered dengan variasi diameter 40mm dan 51mm dalam ST=65mm SL=60mm konstan. Pemodelan serta meshing susunan tube dilakukan dengan software GAMBIT 2.4.6 sementara simulasi dilakukan dengan software FLUENT 18.0. Untuk mendapatkan hasil yang baik, terlebih dahulu dilakukan grid independency test sehingga diperoleh kerapatan mesh yang baik. Hasil akan ditampilkan baik secara kualitatif berupa gambar kontur temperatur, kontur velocity, dan pathline velocity maupun secara kuantitatif berupa grafik distribusi temperatur dinding tube dan flue gas 1 mesh di atas tube.
Berdasarkan hasil simulasi, diketahui bahwa perpindahan panas pada susunan tube staggered lebih baik daripada susunan tube aligned. Namun, jumlah row kritis terhadap sulfuric acid dew point temperature pada susunan tube staggered lebih sedikit daripada susunan tube aligned. Fenomena ini terjadi karena pada susunan tube aligned terdapat daerah secondary flow/vortex lebih besar dibanding susunan tube staggered yang menyebabkan temperatur flue gas turun hingga di bawah sulfuric acid dew point temperature. Sementara perpindahan panas pada diameter tube 51mm lebih baik daripada diameter tube 40mm. Namun, jumlah row kritis terhadap sulfuric acid dew point temperature pada diameter tube 51mm lebih sedikit daripada diameter tube 40mm. Fenomena ini terjadi karena pada diameter tube 40mm terdapat daerah secondary flow/vortex lebih besar dibanding diameter tube 51mm yang menyebabkan temperatur flue gas turun hingga di bawah sulfuric acid dew point temperature.
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Air preheater as one of the components in boiler is used to heat the primary air and secondary air so the combustion in boiler goes well. But most of the times, inappropriate design and installment of air preheater cause failures, one of ithem is corrosion. Corrosion in air preheater can happen when the flue gas temperature drop below the sulfuric acid dew point temperature. Tube alignment and dimension of tube air preheater can determine the distribution of flue gas temperature that flow through the air preheater. Based on this background, the effect of tube alignment and diameter of the tube need to be analyzed in term of sulfuric acid dew point location.
This final project used GAMBIT 2.4.6 and FLUENT 18.0 software to do the simulation of the air preheater. The alignment was made in aligned and staggered alignment with variation of diameter 40mm and 51mm with constant value of ST=65mm and SL=60mm. Drawing of the geometry and meshing was done using software Gambit 2.4.6 while the simulation was done using software FLUENT 18.0. To receive accurate result, the grid independency test was done to get the number of mesh needed until indepency was reached. The result will be displayed qualitative (temperature contour, velocity contour, and velocity pathline) and quantitative (graphic temperature distribution permiter of the tube and flue gas 1 mesh above the tube).
Based on the result, it is known that the heat transfer coefficient in staggered tube alignment better than aligned tube alignment. But, the number of critical row due to sulfuric acid dew point temperature in staggered tube are fewer than aligned tube alignment. This phenomenon was caused by the large area of secondary flow trapped between the tube in aligned tube alignment compare to staggered tube allignment. The flue gas secondary flow will drop below sulfuric acid dew point temperature. While the heat transfer coefficient in diameter tube 51 mm better than 40mm. But, the number of critical row due to sulfuric acid dew point temperature in diameter tube 51mm fewer than 40mm. This phenomenon was caused by larger area affected by secondary flow in tube diameter 40mm. The flue gas secondary flow will drop below sulfuric acid dew point temperature.

Item Type:	Thesis (Undergraduate)
Additional Information:	RSM 621.402 5 Lis s-1 2019
Uncontrolled Keywords:	air preheater, aligned, staggered, sulfuric acid dew point temperature
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Andrew Tirtawijaya Listijabudhi
Date Deposited:	03 Jan 2022 05:41
Last Modified:	03 Jan 2022 05:41
URI:	http://repository.its.ac.id/id/eprint/61875

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