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In Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in Mechanical Engineering ME 518 Code: Time: 1:30-3: Submitted to: Engr. Dominador Go Submitted by: Axalan, Howell Jay M. Baladje. Norisa M. Cabanilla, Darryl Llagas, Argiel John Roquete, Andre Joshua July 19,
Chapter 1 INTRODUCTION A hundred and sixteen years ago, electricity first flowed form geothermal energy in a Tuscany village of Larderello in Italy when a three fourth- horsepower reciprocating engine drive a small generator powered by Prince Ginori Conti. A few bulbs in his boric acid factory was able to light situated amid boron-rich geothermal steam field. In 1914 commercial delivery of geothermally- generated electric transpired. And it started the chase of producing electricity from the heat beneath the earth’s surface as a form of a renewable resources. Geothermal energy is heat that comes from the sub-surface of the earth. In the rocks and fluids beneath the earth’s crust it is contained. And found as far down to earths molten rock, magma. Unlike fossil fuels its renewable energy resource naturally core of earth is scalding. This heat permeates throughout the other layers of the planet, it’s a source of energy that will not deplete. It is best found in areas with high thermal gradients. Those gradients occur in region affected by recent volcanism, in areas located along plate boundaries, such as along the Pacific Ring of Fire including Philippines. To reach superheated fluid, wells are drilled 5,000 to 10,000 feet below the surface of the earth. These production wells bring superheated fluid to the earth surface where it can be used as a heat source in a Geothermal Power plant to generate electricity. Steam is used to drive a turbine and generate electricity. All remaining geothermal fluids are injected back in reservoirs for reuse through injection wells. Technologies used in Geothermal power plants are dry steam power stations, flash steam power stations and binary cycle power stations. Usage depends on the location and type of reservoir
pressure generates additional steam production. At this point, both high and low pressure steam have been produced and are directed to separate pipelines. The water from the second separator is piped t injection wells similar manner to single flash. The high and low pressure steam are directed to separate turbines, each designed for the specific inlet pressure available. The balance of plant is similar to that of a single flash including the vacuum system, condensers and cooling towers. In Binary cycle plant, the thermal energy of the geo fluid is transferred via a heat exchanger to a secondary working fluid for use in a fairly conventional Rankine cycle. The geo fluid itself does not contact the moving parts of power plant, thus minimizing, if not eliminating, the adverse effects of erosion. Binary plants may be advantageous under certain conditions such as low geo fluid temperatures say less than 150 ⁰C, a single flash type is often the best economicC, or geo fluids with high dissolved gases or high corrosion or scaling potential. The latter problems are usually exacerbated when the geothermal liquid flashes to vapor as typically occurs in self-flowing production well. Down well pumps located below the flash level can prevent flashing by raising the pressure above the saturation pressure for the fluid temperature. Moat binary plants operate on pumped wells and the geo fluid remains in liquid phase throughout the plant, from production wells through the heat exchangers to injection wells. An interesting historical note that the first commercial geothermal power plants I Larderello were in fact, binary types. In this design Flash types will be only considered and be used since it is commonly used now a days and its more capable for future expansions. Objectives The main objective of this study is to design a geothermal power plant. As well as the study aims to achieve the following;
The proposed Geothermal Power Plant will be located at the boundary of Kapatagan, Digos and Sibulan, Sta. Cruz, Davao del Sur. Figure 2: View of the Sibulan Production Wells Section II. Civil Facilities The existing soil condition should undergo analysis to determine the proper type of foundation. Storm water drainage should be evaluated based on rainfall intensities, runoff characteristics of soil, facilities for receiving storm water discharge, and local regulations of the location. All graded areas should have stabilized to control erosion by designing shallow slopes to the greatest extent possible and by means of soil stabilization such as seeding, sod, stone, riprap and retaining walls. Building sizes is arranged depending on the approved design, as well as basing on what type of turbines and generators will be used, the relationship of the switchyard to the plant; provisions for future expansion; and, aesthetic and environmental considerations. The main building or the powerhouse will consist of a turbine and generator. Control rooms, offices, locker rooms, machine shops, laboratories and other general spaces will have its own building. Cooling towers and
switchyard area housing of transformer and off to electrical grid will have its own area. Schematic piping will be utilized. Power plant arrangement will permit reasonable access for operation and maintenance of equipment. Careful attention will be given to the arrangement of equipment, valves, mechanical specialties, and electrical devices so that rotors, tube bundles, inner valves, top works, strainers, contractors, relays, and like items can be maintained or replaced. Adequate platforms, stairs, handrails, and kick plates will be provided so that operators and maintenance personnel can function conveniently and safely. Section III. Climatic conditions Air temp. to turbocharger inlet 27 ⁰C, a single flash type is often the best economicC Atmospheric Pressure 750 torr Relative Humidity 60 % Water temp. at charge air cooler inlet 27 ⁰C, a single flash type is often the best economicC Table 1: Climatic conditions based on ISO Conditions Air temp. to turbocharger inlet 48 ⁰C, a single flash type is often the best economicC Atmospheric Pressure 750 torr Relative Humidity 60 % Water temp. at charge air cooler inlet 32 ⁰C, a single flash type is often the best economicC Table 2: Climatic conditions assumed
Figure 3: Plant Layout Design Standards To ensure quality and safe operation, the design of the geothermal power plant will be designed in accordance to the standards set by different organizing body around the world. But primarily the proponents will use the Philippine National Standards since it set the implementing standards in the country. Listed below are the organizations which standards are to be followed.
Stainless-clad steel is used for the shell and stainless steel is used for all internal components to resist corrosion. Type Spray jet, direct-contact low level type Internal Pressure 125 kPA Cooling water 1,030 (^) m^3 / h Cooling water temperature 32.2 C⁰C, a single flash type is often the best economic Type 2x100% 2-stage steam ejector Number of units 2 (Including standby unit) Capacity 1,182 kg / h Type Vertical mixed flow type Number of units 2 Capacity 1,300 t / h Total head 70m Motor Output 500kW Type Induced draft, counter flow, single suction type Number of units 2 Water quantity (^5500) m^3 / h Inlet water temperature 46.6 C⁰C, a single flash type is often the best economic Outlet water temperature 32.2 C⁰C, a single flash type is often the best economic Design wet-bulb temperature 21 C⁰C, a single flash type is often the best economic Fan 2x55kW Type Three-phase horizontal cylindrical revolving field total-enclosed type synchronous generator Capacity 54,600 kVA Voltage 10.5 kVA Power factor 0.7, lag Revolution speed 2500 r/min Frequency 50 Hz Excitation Brushless type Generator Efficiency 85% Table 11: Generator main specifications
Chapter IV DESIGN SELECTION To be able to meet the best and the most appropriate design which to be utilized and in accordance to the objective and scope of the study, the proponents will present two different designs to choose with. And applying trade off analysis in which the designs will be rated and compared. Single flash Geothermal Power Plant (Design 1) h 1 = h 2 1344 kJ / kg h 3 2781 kJ / kg h 4 2416.359 kJ / kg
Design 1 Design 2 Annual Supply 438,000,000 kWh 438,000,000 kWh Manpower ₱ 54,000,000 ₱ 60,864, Maintenance ₱ 328,500,000 ₱ 394,200, Annual Expenses ₱ 382,500,000 ₱ 455,064, Annual Income ₱ 3,857,028,000 ₱3,857,028, Net Income ₱3,474,528,000 ₱3,401,964, Total Net Income ₱2,432,169,600 ₱2,381,374, Total Investment ₱ 4,750,000,000 ₱ 5,000,000, Return of Investment 51.2% 47.62% Table 14: Cost-benefit analysis results Design Constraints Design constraints indicates the limitations on which the design should be considered. The criteria for design includes manufacturability, sustainability, economic and social. Manu actability denotes the ease of fabrication and availability of materials. Sustainability refers to the life cycle of the design with the effect of the environment and its resilience. Economic criteria refer to the cost effectiveness of the design. Lastly, the social criteria point out the difference between the effectiveness of manpower against automated method as well as the rights and safety matters between manual and automated method. Manufacturability
Economic
Conclusion Based on the research conducted as well as data gathering and series of computations it is proven that the design 2 is more suitable for the project which is the double flash geothermal power plant type. Since it is more efficient, and obtained a higher weight using tradeoff analysis compared to single flash type. Even though the return of investment is longer having only 47.62% having a difference of about 3.58% with the design 1 having 51.2% ROI. It still the best choice because the difference is just minimal compared to what its capabilities and design 2 is also more suitable for future expansions. Researchers recommend to gather more data and information in the plant site because it is where really the action starts and it one of the most fundamental part of building a more efficient geothermal power plant
References (1) Fink and Beatty, Standard Handbook for Electrical Engineers, McGraw Hill Book Company, New York, N.Y. 10020 (2) Grant, Ireson and Leavenworth, Principals of Engineering Economy, John Wiley & Sons, Inc., New York, N.Y. 10036 Kent, R. T., (3) IRENA (International Renewable Energy Agency) (2017a). “Featured Dashboard – Capacity Generation”,RESOURCE,http://resourceirena.irena.org/gateway/dashboard/? topic=4&subTopic=16. (4) IRENA (International Renewable Energy Agency) (2017b). “Renewable Cost Database”, IRENA, http:// costing.irena.org/irena-costing.aspx. (5) IRENA (International Renewable Energy Agency) (2017c). “Project Navigator: Technical Concept Guidelines for Geothermal Projects 2017”, IRENA, https://navigator.irena.org/index.html. (6) IRENA (International Renewable Energy Agency) (2014). “Renewable Power Generation Costsin2014”,IRENA,AbuDhabi,http://www.irena.org/DocumentDownloads/Publications/ IRENA_RE_Power_ Costs_2014_report.pdf. (7) Kents Mechanical Engineers Handbook Power Volume, John Wiley& Sons, Inc., New York, N.Y. 10036 (8) Marks Standurd Handbook for Mechanical Engineers, McGraw Hill Book Company, New York, N.Y. 10020 (9) Mason, The Art and Science of Protective Relaying, General Electric Engineering Practice Series, John Wiley & Sons, Inc., New York, N.Y. 10036 (10) Morse, Frederick T., Power Plant Engineering and Design, D. Van Nostrand Company, Inc., New York, N.Y.
