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Design of an Ethylene Plant from Natural Gas Derived Feed

U nited A rab Emirates U niversity C ollege of E ngineering G raduation P roject 2. Design of an Ethylene Plant from Natural Gas Derived Feed. Ismail Abdalla Al-Ali 199900293 Mohamed Saeed Al-Ameri 199905057 Hassain Naje 199900270 Faculty Advisor Dr. Farid Benyahia

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Design of an Ethylene Plant from Natural Gas Derived Feed

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  1. United Arab Emirates University College of Engineering Graduation Project 2 Design of an Ethylene Plant from Natural Gas Derived Feed Ismail Abdalla Al-Ali 199900293 Mohamed Saeed Al-Ameri 199905057 Hassain Naje 199900270 Faculty Advisor Dr. Farid Benyahia Coordinator: Dr. Munjid Maraqa

  2. Content of presentation • Introduction • PID & HAZOP Study of Section of the Plant • Project Costing & Economic Evaluation • Mechanical Design of a Selection of Major Process Equipment • Conclusion

  3. Objective • To design, cost and evaluate safety and environmental impacts of an ethylene plant in the UAE.

  4. Introduction • The work done in GP1 • Ethylene marketing • Safety and environmental impact assessment • Process technologies of ethylene production (Licensed Petrochemical Processes) and make a comparison between technologies • Process description and representation by a PFD • The plant site location • Preliminary cost • Completed material balance • Completed energy balance

  5. The work done in GPII • Piping and instrumentation diagram (PID) and HAZOP study of section of the plant • Detail economic evaluation of the process • Mechanical design of a selection of major process equipment

  6. PID & HAZOP Study of Section of the Plant • The Piping and Instrument Diagram (PID) shows the engineering details of the equipment, instruments, piping, valves and fittings; and their arrangement. • Instruments are provided to monitor the key process variable during plant operation. • The primary objective of the designer when specifying instrumentation and control schemes are: • Safe plant operation • Production rate • Product quality • Cost

  7. The Piping and Instrument Diagram (PID) as in Figure 1 without HAZAP study. • Hazards and operability studies (HAZOP) involves a systematic study of the process or parts of it. • It is applying special “guide words” to generate thought about the way deviations from the intended operating conditions can cause dangerous situations.

  8. Example of HAZOP study HAZOP for cracking section Table 1: HAZOP study in S1 for flow deviation

  9. The PID has been upgraded after the HAZOP study to improve the process safety as in Figure 2.

  10. Project Cost and Economic Evaluation • Cost plays an active role for the engineering life. • The design engineer needs to be able to make quick, rough, cost estimates to decide between alternative designs and for the project evaluation. • Costing of the Project: • Preliminary (approximate) estimates, accuracy typically ± 30 %. • Authorization (Budgeting) estimates, accuracy typically ± 10-15 %. • Detailed (Quotation) estimates, accuracy typically ± 5-10 %.

  11. Fixed Capital • It is the total cost of the plant ready for start up. • This cost doesn't return back when the project is finish and it paid one time. • It includes the cost of: • Design and other engineering and construction supervision. • All items of equipment and their installation. • All piping, instrumentation and control systems. • Building and structure. • Auxiliary facilities, such as utilities, land and civil engineering work.

  12. Working Capital • It is the additional investment needed • includes the cost of: • Start-up. • Initial catalyst charges. • Raw materials and intermediates in the process. • Finish product inventories. • Funds to cover outstanding accounts from customers. • Most of the working capital is recovered by the end of the project. • The total investment needed for a project is the sum of the fixed and the working capital.

  13. Step Counting Methods The correlation of Timms, IChemE (1988) gives a simple equation for gas phase processes. C = 8000 N Q0.615 • C = capital cost in US dollars • N = number of functional units • Q = plant capacity, tonne per year

  14. C = 8000 * 18 * (600000)0.615 = 515,140,282 US Dollars This cost is valid for 1998 according to the correlation shown above Cost 2003 = (Cost Index 2003)/ (Cost Index 1998) * (Cost 1998) = (398) / (390) * (515,140,282) = 525,707,262 US Dollars Cost of the plant in 2004 = 496501303 * 1.02 = 536,221,407 US dollars Cost of the plant in 2005 = 496501303 * 1.02 = 546,945,835 US dollars or approximately 547 million US Dollars

  15. Total Investment • Investment is spread over 4 years: • Total investment = Year 1 + Year 2 + Year 3 + Year 4 = 546,945,835 US Dollars

  16. Operating Cost • Fixed Operating Cost • For each year up to year 10: Operating cost = 0.037 * Capital cost = 20,236,996 $ • From year 10 up to year 17: Operating cost = 0.046 * Capital cost = 25,159,508 $ • From year 17 to year 30: Operating cost = 0.055 * Capital cost = 30,082,021 $ • Variable Operating Cost • For each year up to year 17: Variable cost = 17 $/tone • From year 17 to year 30: Variable cost = 22 $/tone

  17. Rate of Return (ROR) and Discount Cash Flow (r) Calculations Where: Cumulative net cash flow at end of the project = 6856.8 *106 $ Life of the project = 30 year Original investment = 546945835.2 $ ROR = 41.79% The discount rate (r) = 33.74%

  18. Mechanical Design of a Selection of Major Process Equipment Economic • The chemical engineer is normally required to specify the main dimensions of the pieces of equipment. • The mechanical design is done to: • Shell and tube heat exchanger • Column of DET • Column of DEE

  19. Heat Exchanger • The transfer of heat to and from process fluids is an essential part of most chemical processes. • The shell and tube exchanger is far the most commonly used type of heat transfer equipment used in the chemical and allied industries.

  20. Ui, W / (m2oC) 30.00 30.00 30.00 Provisional area, m2 7473.81 7473.81 7473.81 Tube outside diameter, mm 32.00 27.00 18.00 Tube inside diameter, mm 30.00 25.00 16.00 Tube length, m 15.00 12.00 8.00 Area of one tube, m2 1.51 1.02 0.45 Number of tube 4957 7343 16521 Bundle diameter, mm 2896.68 2936.33 2858.45 Shell diameter, mm 3023 3064 2984 L / Ds 4.96 3.92 2.68 Tube cross sectional area, m2 706.86 490.87 201.06 Tube per pass 4957 7343 16521 Total flow area, m2 3.50 3.60 3.32 Ethane mass velocity, kg / s m2 12.88 12.52 13.58 Ethane velocity, m/s 5.99 5.82 6.32 Re 33834.29 27405.78 19031.79 Pr 0.80 0.80 0.80 hi, W / (m2oC) 106.74 112.64 127.05 Results of calculation for different tube diameters Table : The mechanical design result of HE 2 at different tube inside diameter (30, 25 and 16 mm).

  21. Table 3: Insulation of HE 2 and the shell thickness.

  22. Figure : Shell and Tube Heat Exchanger 2

  23. Distillation Columns • The separation of liquid mixtures into their several components is one of the major processes of the chemical and petroleum industries, and distillation is the most widely used method of achieving this end.

  24. The result of DEE calculations Table : Summary of the results for various plate spacing

  25. Figure : DEE Column

  26. The result of DET calculations Table 5: The result of DET calculations

  27. Figure : DET Column

  28. Conclusion • The HAZOP study was done to enhance the level of instrumentation in order to improve safety. This was comprehensively achieved by applying different guide words to process variable deviations like temperature, pressure and flow (No, Less and More). • The economic evaluation of the project was carried out. The plant capital cost was found to be approximately 547 million US Dollars. • The rate of return (ROR) was found to be 41.71 % and the discount cash flow (r) was 33.37 %. • The project was found to be economically viable because ROR is larger than r. This means that the plant can be built and operated at a good profit.

  29. Since our process was rather large, the main equipment considered for detailed mechanical design were heat exchanger number 2 (HE 2) in the cracking section, deethylenizer column (DET) and deethanizer column (DEE) in the purification section. • The design calculation of HE 2 showed that: • Inside tube diameter = 16 mm, • Shell diameter = 3 m, • Ethane velocity = 6.32 m/s, • Number of baffles = 13, • The insulation thickness = 79 mm, and • The shell thickness = 10 mm. • The design calculation of DET column showed that: • The diameter of column = 2.50 m, • The height of column = 56 m, and • The column shell thickness = 4 mm. • The design calculation design of DEE showed that (at plate spacing = 0.5 m) : • The diameter of column = 1.70 m, • The height = 11.5 m, • The isolation = 0.032 mm, and • The column shell thickness = 4 mm.

  30. Thank YouFor Listening

  31. The Diagram of Ethylene Process with PID

  32. The Diagram of Ethylene Process with PID After HAZOP Study

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