Self-Tuning PID-Genetic Algorithm Controller for Steam Drum Boiler Water Level Control System

A control system with uncertainty or unpredictable disturbance needs more effort to be controlled. A conventional PID Controller is the most popular method used in industries. It was tuned and adjusted by the designer, and it has fixed parameters during operation. However, the disturbance effect causes the desired system performance unreachable. By using a self-tuning controller, the problem should be tackled. In this paper, the PID-Genetic Algorithm (PID-GA) controller was proposed and tested with the steam drum water level control system of a steam power plant. Variation in power load causes noisy water level characteristics and should be maintained at + 0.4 meters from the setpoint to prevent the power plant trip. From the simulation, PID-GA can reduce disturbance of the minimum, nominal, and maximum load with perturbation peaks 0.18 m, 0.22 m, and 0.26 m respectively.Keywords: genetic algorithm, NWL, PID-GA, steam drum, steam power plant.

Ethylene Yield from a Large Scale Naphtha Pyrolysis Cracking Utilizing Response Surface Methodology

Statistical software is a robust application that has proven reliable worldwide. However, it is not normally used in the actual large scale olefin plant as it relies on the simulation software by Olefin Licensor should any issue rises. The study was conducted in a newly commissioned large scale olefin plant to see the impact of various operating variables on the ethylene yield from Short Residence Time (SRT) VII Furnace. The analysis was conducted utilizing statistical analysis, Response Surface Methodology (RSM) in Minitab Software Version 18 to develop a reliable statistical model with a 95% confidence level. The historical data was taken from the Process Information Management System (PIMS) Software, PI Process Book Version 2015, and underwent both residuals and outliers removal prior to RSM analysis. 10 variables were shortlisted from the initial 15 identified variables in the studied SRT VII via Regression analysis due to RSM limitation to conduct the larger analysis in Minitab Software Version 18. The Response Optimizer tool showed that the ethylene yield from naphtha pyrolysis cracking in the studied plant could be maximized at 34.1% with control setting at 600.39 kg/ hr of Integral Burner Flow, 6.81% of Arch O2, 113.42 Barg of Steam Drum Pressure, 496.96°C of Super High Pressure (SHP) Temperature, 109.11 t/hr of SHP Boiler Feed Water (BFW) Flow, 92.78 t/hr of SHP Flow, 63.50 t/hr of Naphtha Feed Flow, and -13.38 mmHg of Draft Pressure.

Ethylene Yield from Pyrolysis Cracking in Olefin Plant Utilizing Regression Analysis

Ethylene yield is significant in showing the performance of the steam cracker furnace in the olefin plant. This study was conducted in the actual large-scale olefin plant to see the impact of various variables towards the ethylene yield. The analysis was conducted utilizing Regression Analysis in Minitab Software Version 18 to develop a reliable ethylene yield model. The model concluded that ethylene yield in the studied plant was contributed by the factor of -0.000901, 0.02649, -0.282, 0.16, -0.0834, 0.1268, and 0.0057 of Hearth Burner Flow, Integral Burner Flow, Steam Drum Pressure, Super High-Pressure Steam (SHP) Boiler Feed Water Flow, SHP Flow, Naphtha Feed Flow, and Stack NOx Emission respectively. The Response Optimizer tool also showed that the ethylene yield from naphtha liquid feed utilizing pyrolysis cracking can be maximized at 32.55% with control setting at 9,476.41 kg/hr of Hearth Burner Flow, 608.56 kg/hr of Integral Burner Flow, 112.93 Barg of Steam Drum Pressure, 109.11 t/hr of SHP Boiler Feed Water Flow, 86.42 t/hr of SHP Flow, 63.49 t/hr of Naphtha Feed Flow and 126.23 mg/m3 of Stack NOx Emission.

Analisis Kebocoran Tube Outlet Header LP Evaporator HRSG dengan Metode RCFA

Ditemukan adanya kebocoran pada tube outlet header LP evaporator HRSG. Kebocoran tersebut terjadi di lokasi pipa masuk ke header sisi keluar dan pada belokan pipa menuju header. Kebocoran pada pipa dapat menyebabkan steam drum tidak mampu memenuhi syarat minimum level air sehingga mengakibatkan sistem proteksi pada HRSG memberikan sinyal untuk trip dan sistem menjadi open cycle yang berdampak pada penurunan daya mampu atau derating. Hal tersebut apabila tidak ditangani maka dapat menyebabkan kerugian, dimana seharusnya gas hasil pembakaran dapat termanfaatkan secara maksimal. Untuk mengatasi hal tersebut, diperlukan metode pemecahan masalah sampai ke akarnya menggunakan Ishikawa Diagram. Penelitian ini bertujuan untuk mengetahui akar penyebab terjadinya kerusakan tube outlet header LP evaporator HRSG dan mengetahui solusi untuk mengatasi kebocoran HRSG agar tidak terulang. Hasil penelitian menunjukkan bahwa dari kajian 5M yang memiliki faktor paling berpengaruh dalam kaitan terjadinya kebocoran adalah karena faktor material; nilai kriteria fleksibilitas pipa melebihi batas yaitu sebesar 0,04, ketebalan pipa telah mendekati batas minimum yaitu sebesar 2,58 mm; pengoperasian fluktuatif, dan management; waktu pemeliharaan melewati batas equivalent operating hour (EOH). Untuk mengatasi kebocoran yang terjadi pada pipa HRSG dapat dilakukan pengecekan terhadap distribusi aliran gas hasil pembakaran, menjaga kualitas air, mengoperasikan HRSG secara base load dan pemeliharaan sesuai EOH.