Perancangan Kettle Reboiler pada Sistem Gas Treatment Unit

MOCHAMAD RAMDAN, Ir. Joko Waluyo, M.T., Ph.D., IPM

2022 | Skripsi | S1 TEKNIK MESIN

Kettle reboiler merupakan alat penukar kalor jenis shell and tube yang digunakan untuk menghasilkan uap pada shell side. Fluida dingin ammonia pada sisi shell diuapkan oleh fluida panas steam pada sisi tube. Fluida pada shell side dan tube side mengalami perubahan fasa sehingga diperlukan analisis aliran dua fasa untuk perhitungan pressure drop dan heat transfer coefficient. Fluida pemanas yang terdapat pada tube side terendam oleh fluida dingin sehingga pertukaran kalor terjadi secara pool boiling. Karakteristik pool boiling berlangsung pada nucleate boiling regime agar diperoleh nilai heat flux yang optimal. Tugas akhir ini bertujuan untuk menghasilkan rancangan kettle reboiler yang mengakomodir sejumlah heat exchanged duty dan mengetahui unjuk kerja kettle reboiler dengan variasi laju aliran massa pada sistem Gas Treatment Unit. Perancangan kettle reboiler mengacu pada Tubular Exchanger Manufacturers Association (TEMA) Standard dan American Association of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII Division 1. Kettle reboiler data sheet yang mencakup data termal dan mekanikal digunakan untuk menentukan berbagai variabel seperti spesifikasi tube, kettle reboiler dimension, mean temperature, overall coefficient heat transfer, thickness, dan flange class. Hasil perancangan diperoleh kettle reboiler memerlukan heat exchanged duty 12.855,6 kW, spesifikasi tube jenis u-tube, BWG 16, panjang 6.096 mm, tube pitch 25,4 mm dengan square layout pattern, dan material 316 stainless steel (17 Cr, 12 Ni), dibutuhkan sebanyak 2.108 tube, 1.371,6 mm untuk shell inside diameter, kettle inside diameter sebesar 2.455,34 mm, dan overall coefficient heat transfer sebesar 1.406,34 W/m2�K. Kettle reboiler bekerja pada internal design pressure 10.600 kPa dan design temperature 185 �. Material SA-516- 70, joint efficiency bernilai 1, dan 3,175 mm untuk corrosion allowance dipilih untuk perancangan shell dan head lalu diperoleh nominal thickness 127 mm. Perancangan nozzle didapatkan size 10� Sch 120 untuk shell inlet dan liquid outlet nozzle, 14� Sch 120 untuk shell outlet dan tube inlet nozzle, dan 3� Sch 160 untuk tube outlet nozzle. Material A 105 ditentukan sebagai material flange dan diperoleh flange class 900.

Kettle reboiler is a shell and tube type heat exchanger used to produce steam on the shell side. The cold fluid ammonia on the side of the shell is evaporated by the steam hot fluid on the side of the tube. The fluid on the shell side and tube side undergoes phase changes so that a two-phase flow analysis is needed for the calculation of pressure drop and heat transfer coefficient. The heating fluid contained on the tube side is submerged by cold fluid so that heat exchange occurs in pool boiling. The characteristics of pool boiling take place in the nucleate boiling regime in order to obtain an optimal heat flux value. This final project aims to produce a reboiler kettle design that accommodates a number of heat exchanged duties and knows the performance of the kettle reboiler with variations in mass flow rates in Gas Treatment Unit system. The design of the kettle reboiler refers to the Tubular Exchanger Manufacturers Association (TEMA) Standard and the American Association of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII Division 1. Kettle reboiler data sheets include thermal and mechanical data are used to determine various variables such as tube specifications, kettle reboiler dimension, mean temperature, overall coefficient heat transfer, thickness, and flange classes. The design results obtained by the kettle reboiler requires a heat exchanged duty of 12.855,6 kW, u-tube type tube specifications, BWG 16, length 6.096 mm, tube pitch 25,4 mm with square layout pattern, and material 316 stainless steel (17 Cr, 12 Ni), it takes 2.108 tubes, 1.371,6 mm for shell inside diameter, kettle inside diameter of 2.455,34 mm, and overall coefficient heat transfer of 1.406,34 W/m2�K. The kettle reboiler works on an internal design pressure of 10.600 kPa and a design temperature of 185 °C. SA-516-70 material, joint efficiency value of 1, and 3,175 mm for corrosion allowance were selected for the design of the shell and head and then obtained a nominal thickness of 127 mm. Nozzle design obtained size 10" Sch 120 for shell inlet and liquid outlet nozzle, 14" Sch 120 for shell outlet and tube inlet nozzle, and 3" Sch 160 for tube outlet nozzle. Material A 105 was specified as flange material and obtained flange class 900.

Kata Kunci : kettle reboiler, shell and tube heat exchanger, pool boiling, perancangan, TEMA.