Perancangan Horizontal Pressure Vessel Tipe Preheater Dan Sistem Perpipaan Pada Proyek Blawan Ijen Geothermal Unit #1

Abstract

The Blawan Ijen Unit 1 Geothermal Power Plant (PLTP) project in Bondowoso Regency,
East Java, utilizes geothermal energy potential as a sustainable renewable energy source. One of its
vital components is a preheater, a horizontal pressure vessel that functions as a heat exchanger to
increase the temperature of the cyclopentane working fluid before the energy conversion process takes
place. With a capacity of 21,000 liters, a design pressure of 3.2 MPa, and a design temperature of
210°C, this preheater is designed in accordance with international standards ASME Section VIII
Division 1 using material SA-516 GR 70, with the assistance of PV Elite software for pressure vessel
analysis and CAESAR II for piping stress analysis. Manual calculations were performed as validation
of the software results. The minimum shell and head thicknesses were determined to be 16.529 mm
each, with a Maximum Allowable Working Pressure (MAWP) of 4.1 MPa and a Maximum Allowable
Effective Pressure (MAEP) of 0.162 MPa (shell) and 1.556 MPa (head). The MAEP values meet the
design limits without the use of stiffener rings. The saddle strength analysis yielded a stress of 173.33
MPa, below the material's allowable stress limit. Of the 8 nozzles designed, 6 required reinforcing
pads, and all welded joints met the strength standards for operational loads. The stress analysis using
the von Mises stress value of 27.579 MPa is considered safe as it remains below the material's allowable
stress limit. The nozzle inlet load analysis shows a maximum pressure of -281 lb,lower than the
maximum allowable limit of 4496 lb, while the outlet shows a value of 3843.5 lb/ft, which is lower than
the maximum limit of 29503.7 lb/ft, ensuring the pipe-nozzle connection is safe with the addition of
Thermal Movement on the Dy axis of 2.2 mm and Dz of 4.5 mm at the nozzle inlet, For the nozzle outlet
axis, the addition is Dy 0.27 mm, Dz 3.22 mm. These results demonstrate that the designed preheater
meets all technical and safety criteria and can serve as a reference for the development of pressure
vessel equipment for geothermal power plants and renewable energy projects in Indonesia