Lesson 1.0_Introduction to Power Plant_Problem Solving (1).pdf

NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POW...

NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT 1.1 Learning Objectives Upon completion of this chapter, the students are able to: 1. Define what is a Power Plant, 2. Enumerate different sources of energy, 3. Familiarized with the basic concepts of Power Plant, 4. Classify different types of power plants and define their functions, 5. Review the vapor power cycles, and 6. Solve problems related to vapor power cycles 1.2 Introduction to Power Plant Power Plants are used for electric power generation. Electric power plays an important role in the growth of industry. A countries development is measured by the power generation industry and its power demand. The standard of living in a country is normally related to the consumption of electricity in that country. A Power Plant may be defined as a machine or assembly of equipment that generates and delivers a flow of mechanical or electrical energy. The main equipment for the generation of electric power is generator. When coupling it to a prime mover runs the generator, the electricity is generated. The type of prime move determines the type of power plants. Classifications of Power Plants Power plants are broadly classified into two types: 1. Conventional Sources of Energy (Non‐renewable Energy) a. Steam Power Plant b. Hydroelectric Power Plant c. Diesel Power Plant d. Gas Turbine Power Plant e. Nuclear Power Plant 2. Non‐Conventional Sources of Energy (Renewable Energy) a. Solar Power Plant b. Wind Power Plant c. Tidal & Wave Power Plant d. Ocean Thermal Energy Conversion e. Biomass Power Plant f. Geothermal Power Plant Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Sources of Energy 1. Renewable Energy is continuously produced in nature, and it will not get exhausted eventually in the future. a. Solar Energy b. Wind Energy c. Geothermal Energy d. Tidal Energy e. Biomass Energy 2. Non-renewable Energy will get exhausted eventually in the future. a. Solid, Liquid and Gaseous fuels b. Hydraulic Energy Types of Energy There are various types of energy, which include electrical, thermal, nuclear, chemical, mechanical and radiant energy. 1. Nuclear Energy produces heat by fission on nuclei, which is generated by heat engines. Nuclear energy is the world’s largest source of emission-free energy. There are two processes in Nuclear energy fission and fusion. In fission, the nuclei of uranium or plutonium atoms are split with the release of energy. In fusion, energy is released when small nuclei combine or fuse. The fission process is used in all present nuclear power plants, because fusion cannot be controlled. 2. Thermal Energy is associated with the random motion of atoms in an object. The kinetic and potential energy associated with this random microscopic motion is called thermal energy. 3. Chemical Energy is a form of energy that comes from chemical reactions, in which the chemical reaction is a process of oxidation. Potential energy is released when a chemical reaction occurs, which is called chemical energy. 4. Radiant Energy exists in a range of wavelengths that extends from radio waves that many be thousands of meters long to gamma rays with wavelengths as short as a million-millionth (10–12) of a meter. Radiant energy is converted to chemical energy by the process of photosynthesis. 5. Mechanical Energy is the sum of the kinetic energy and the potential energy. a. Potential Energy exists whenever an object which has mass has a position within a force field. b. Kinetic Energy is the energy of motion. An object in motion, whether it be vertical or horizontal motion, has kinetic energy. 6. Electrical Energy is the power an atom's charged particles have to cause an action or move an object. The movement of electrons from one atom to another is what results in electrical energy. 1.3 Review of Thermodynamics Principle 1. Cycle is a series of two or more processes in which the final state is the same as the initial state. 2. Vapor Power Cycle is a power generating cycle that uses steam or water vapor as the working substance. This cycle differs from an internal combustion engine cycle because the combustion occurs in the boiler, unlike that of an IC engine where combustion occurs inside the working cylinders. 3. Pure Substance is a substance that has a fixed chemical composition throughout. 4. Steam is defined as water vapor suspended in the air. It is produced by heating water and carries large quantities of heat within itself. Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT 5. Saturation Temperature is the temperature at which liquid start to boil or the temperature at which vapors begin to condensate. e.g. Water boils at 100°C at atmospheric condition (101.325 kPa) Steam condenses at 311.06°C at 10 MPa 6. Subcooled Liquid is one which has a temperature lower than the saturation temperature corresponding to the existing pressure. e.g. Liquid water at 60°C and 101.325 kPa is subcooled liquid. From steam table, at 101.325 kPa = 100°C 7. Compressed Liquid is one which has a pressure higher than the saturation pressure corresponding to the existing temperature. e.g. Liquid water at 110 kPa and 100°C is compressed liquid. From steam table, at 100°C = 101.325 kPa 8. Saturated Liquid is a liquid at the saturations (saturation temperature or saturation pressure) which has temperature equal to the boiling point corresponding to the existing pressure. It is pure liquid(no vapor content) e.g. Liquid water at 233.90°C and 3 MPa From steam table, tsat at 3MPa = 233.90°C 9. Vapor is the name given to a gaseous phase that is in contact with the liquid phase, or that is in the vicinity of a state where some of it might be condensed. 10. Saturated Vapor is a vapor at the saturation conditions (saturation temperature and saturation pressure). It is 100% vapor (no liquid or moisture content) e.g. Steam at 212.42°C and 2 MPa 11. Superheated Vapor is a vapor having a temperature higher than the saturation temperature corresponding to the existing pressure. e.g. Steam at 300°C and 5 MPa From steam table, tsat at 5MPa = 263.99°C 12. Degrees of Superheat (°SH) is the difference between the actual temperature of superheated vapor and the saturation temperature for the existing pressure. °SH = actual superheated temp. – tsat at existing pressure e.g. Determine the degrees of SH of superheated steam at 200°C and 101.325 kPa. °SH = 200-100 = 100°C (tsat at 101.325 kPa = 100°C) 13. Degrees of Subcooled (°SB) is the difference between the saturation temp. for the given pressure and the actual subcooled liquid temp. °SB = tsat at given P – actual liquid temperature e.g. Determine the degrees of SB of liquid water at 90°C and 101.325 kPa. °SB = 100-90 = 10°C (tsat at 101.325 kPa = 100°C) 14. Wet Vapor is combination of saturated vapor and saturated liquid. 15. Quality (x) is the percent by weight that is saturated vapor. x = (mg/m) x 100; where m = mf + mg 16. Moisture (y) is the percent by weight that is saturated liquid. y = mf/m x 100; where m = mf + mg For saturated liquid: y=100%, x=0% Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT For saturated vapor: y=0%, x=100% For wet vapor: 0 < x < 100 & 0 < y < 100 17. Latent Heat of Vaporization is the amount of heat added to/remove from the substance in order to convert it from saturated liquid/saturated vapor to saturated vapor/saturated liquid with the temperature remains constant. e.g. hfg at 100°C = 2257.0 kJ/kg 18. Critical Point is the point that represents the highest temperature at which liquid and vapor can coexist in equilibrium. 19. Triple Point is the point where solid, liquid, and vapor are present. 20. Sensible Heat is the heat that causes change in temperature without change in phase. e.g. Heat added in raising the temperature of steam from 100°C at 101.325 kPa to 150°C 21. Latent Heat is the heat that causes change in phase without change in temperature e.g. Heat added converting 1 kg of water 100°C and 101.325kPa to 1 kg of steam at 100°C and 101.325kPa 1.4 Vapor Power Cycle A. Rankine Cycle Ideal Rankine cycle is composed of the following processes: 1 – 2: Isentropic Expansion, s = C 2 – 3: Constant pressure Heat Rejection, P = C 3 – 4: Isentropic Pumping, s = C 4 – 1: Constant pressure Heat Addition, P = C In the ideal cycle, the state of steam leaving the steam generator and entering the engine is the same as well as the state of feed water leaving the pump and entering the steam generator. This means that there is no pressure drop and no heat leakage in the steam line and feed water line. (ms = mf) The quantity of the working medium within the system is constant. This implies that there are no leakages in the system. Fig. 1.1 Schematic Diagram of a Rankine Cycle Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.2 T-S Diagram of a Rankine Cycle B. Reheat Cycle Moisture is harmful to the blades of the turbine. It causes erosion and cavitation of the turbine blades. Reheating minimizes the moisture content and at the same time increases the efficiency of the cycle. Steam is usually withdrawn and reheated few degrees before the saturation point. The ideal reheat cycle with one stage of reheating is composed of the following process: 1-2: partial isentropic expansion in the turbine, s=C 2-3: constant pressure re-superheating in the reheater, P=C 3-4: complete isentropic expansion in the turbine, s=C 4-5: constant pressure rejection of heat in the condenser, P=C 5-6: adiabatic pumping process, s=C 6-1: constant pressure addition of heat in the boiler, P=C Fig. 1.3 Schematic Diagram of a Reheat Cycle Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.4 T-S Diagram of a Reheat Cycle C. Regenerative Cycle More than half of the heat added to the water in the boiler is just wasted and rejected in the condenser. In order to utilize some of these heats that would have been wasted and rejected in the condenser, part of throttle steam is extracted or bled for feed water heating after it has partially expanded in the turbine. The extraction/bled points occur near the saturation state. Effects of Regenerative Feed Water Heating 1. Increase in thermal efficiency. 2. Decrease in the moisture content during the later stages of expansion Fig. 1.5 Schematic Diagram of a Regenerative Cycle with one stage of Extraction Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.6 T-S Diagram of a Regenerative Cycle D. Reheat-Regenerative Cycle In this cycle, the reheat cycle and the regenerative cycle are combined to attain the following objectives. 1. Further improvement in the overall thermal efficiency. 2. Further reduction in the moisture content of steam during the latter part of the expansion process. Case 1 Assume an ideal reheat regenerative cycle: after some expansion, steam is extracted for feedwater heating, after further expansion, there is a reheat; then expansion to exhaust. Write the equations for a) the quantity of extracted steam, b) the network, and c) thermal efficiency. The equations should refer to T-S diagram with named points. Fig. 1.7 Plant Layout Case 1 Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.18 T-S Diagram Case 2 Assume an ideal reheat regenerative cycle with, first, an extraction for feedwater heating, then later a single reheating, and finally, two extraction points for feedwater heating. Sketch the energy diagram and write equations for a) the quantity of steam extracted at each point b) the work from QA and QR and the turbine work, and c) thermal efficiency of the cycle. The equation should refer to a TS diagram with named points. Fig. 1.9 Plant Layout Case 2 Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.10 T-S Diagram Case 3 The same as Case 2 except that the three extraction points occur after the reheating. Fig. 1.11 Plant Layout Case 3 Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.12 T-S Diagram Case 4 Assume an ideal reheat regenerative cycle; after some expansion, part of the steam is extracted for feedwater heating, the remainder are withdrawn and reheated to the original temperature; after further expansion, a second extraction occurs, then expansion to exhaust. Write the equations for a) the quantity of steam extracted and the turbine work. Fig. 1.13 Plant Layout Case 4 Prepared by: Engr. Anthony Vic C. Agulan NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT Fig. 1.14 T-S Diagram Prepared by: Engr. Anthony Vic C. Agulan  NUEVA ECIJA UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF ENGINEERING MECHANICAL ENGINEERING DEPARTMENT ME 414 POWER PLANT ENGINEERING WITH RENEWABLE ENERGY LESSON 1 INTRODUCTION TO POWER PLANT 1.5 SAMPLE PROBLEMS 1) A turbine receives steam at 10.0 MPa, 600°C and exhaust it at 0.2 MPa. Draw a schematic diagram and plot the condition of the steam in TS diagram. Also determine the following: a. enthalpies at all point, kJ/kg b. QA & QR, kCal/kg c. WP & WT, BTU/lbm d. net cycle work, lbf.ft/lbm and e. thermal efficiency of Rankine cycle and Rankine engine, % 2) In an ideal reheat cycle, steam is generated at 6.30 MPa, 450°C and partially expands to 0.84 MPa. At this point, the steam is withdrawn and passed through a reheater. It enters the turbine at 0.84 MPa and 480°C. Complete expansion now occurs to the condenser pressure of 0.02 MPa. Find the following: a. Enthalpies b. Total heat added and rejected c. Total turbine work and pump work d. Net cycle work e. Cycle efficiency and engine efficiency 3) A Rankine steam power plant operates with one steam bleed for feedwater heating. Steam enters the turbine at 15 MPa and 600°C. It is condensed at a pressure of 10 kPa. Steam bled out from the turbine at a pressure of 1.2 MPa for feedwater heating. Draw the T-S diagram and schematic diagram. Find the following: a. Enthalpy at all points b. Mass of steam bled, m c. QA & QR d. WT, WP, et e. ee 4) Steam at 5 MPa and 365°C enters a turbine and expands until it becomes saturated. The steam is withdrawn and reheated to 330°C and 1.25 MPa. After expansion in the turbine to 130°C, m1 kg is extracted for feedwater heating. The remaining steam expands to the condenser pressure at 0.016 MPa. For 1 kg of steam, find Wnet, ec, ee, and the ideal steam rate. Prepared by: Engr. Anthony Vic C. Agulan