Basics of Civil and Mechanical Engineering
- 1. BE8252-BASIC CIVIL AND MECHANICAL ENGINEERING PREPARED BY, R.PERIYASAMY ASSISTANT PROFESSOR DEPARTMENT OF MECHANICAL ENGINEERING
- 2. POWER PLANT ENGINEERING A Power Plant or Power station is a machine or assemblage of equipment's that produces and delivers a flow of electrical energy. Power plants are used for the generation of electric power. In India, there has been considerable increase in power development under various power plants “Life without electric power is an unimaginable”
- 3. SELECTION OF POWER PLANT • Availability of fuel and water • Availability of fuel storage facility • Transportation facility • Availability of land • Environmental conditions • Requirement of labours • Efficiency of the plant • Capacity of the Plant • Distance from the load centre • Life of the plant • Availability of time period for power production • Cost of fuel used. • Nature of losses • Depending on noise of vibration
- 4. TYPES OF POWER PLANT Steam or Thermal power plant Hydroelectric or Hydel power plant Nuclear power plant Diesel power plant Gas Turbine power plant
- 6. THERMAL (OR) STEAM POWER PLANT Steam is used as working fluid. The heat energy is converted into mechanical energy by the steam turbine and that mechanical energy is used for generating power with the help of generator. Heat energy Mechanical Energy Electrical Energy
- 7. THERMAL (OR) STEAM POWER PLANT • Boiler----- Turbine------ Generator • Boiler – Fuel Heat Energy • Turbine - Heat Energy Mechanical Energy • Generator - Mechanical Energy Electrical Energy
- 8. THERMAL (OR) STEAM POWER PLANT • In consists of four main circuits Coal and Ash circuit Air and Flue gas circuit Feed water and steam circuit Cooling water circuit
- 9. THERMAL POWER PLANT VIDEO
- 11. EQUIPMENTS • Air preheater: – to preheat the combustion air by means of exhaust gas • Condenser: – The main purposes of the condenser are to condense the exhaust steam from the turbine for reuse in the cycle and to maximize turbine efficiency by maintaining proper vacuum • Economiser: – It is used to preheat the water used for boiler by means of exhaust gases escaping through chimney
- 12. CHARACTERISTICS Low cost as compared with hydro power plant High efficiency Reduced water requirement Higher reliability and availability Reduced environmental impact in terms of air pollution
- 13. ADVANTAGES Initial cost is low compared to hydel plant Less space is required Generation of power is continuous The power plant can be located near load centre, so the transmission cost and losses are considerably reduced The construction of thermal power plants are less period of time
- 14. DISADVANTAGES Maintenance and operating cost are High Power generation cost is high compared with Hydel power plant. Life of the thermal power plant is hardly about (30-40 years) compared with the life of the hydel power plant ( 100- 125 years) Transportation of fuel is a major problem in this type of power plant. Air pollution is the major problem
- 15. MAJOR PROBLEM •Ash handling •Air Pollution
- 16. SELECTION OF SITE FOR A STEAM POWER PLANT • The location of the plant should be at a minimum distance from the load centre ( consumer) to avoid transmission losses. • Availability of water is a desirable factor. • The water should be preferably free from salt to reduce the cost for water treatment. • The soil should be satisfactory for a strong foundation. • The site should be away from thickly populated areas to reduce the effect of pollution ( such as smoke, Ash and heat from the plant ) • Adequate transport facility is desirable. • Space should be available to store Coal and disposal of Ash
- 17. THERMAL POWER PLANTS IN TAMILNADU Name of the power station capacity • Neyveli - 2990 MW • Tuticorin - 1,050 MW • Ennore - 450 MW • North Madras - 1830 MW • Mettur - 1,440 MW
- 19. HYDEL (OR) HYDROELECTRIC POWER PLANT • Hydro means water • Water is used as working fluid • The potential energy of water stored at higher level in a dam is converted into mechanical energy which is used for power generation Potential energy Mechanical Energy Electrical Energy
- 20. HYDEL (OR) HYDROELECTRIC POWER PLANT DEVICE ENERGY CONVERSION • Dam – water Potential Energy • Turbine - Potential Energy Mechanical Energy • Generator - Mechanical Energy Electrical Energy
- 21. CLASSIFICATION OF HYDEL POWER PLANT S.No HEAD TYPE OF POWER PLANT TYPE OF TURBINE 1 Above 100 m High head Pelton wheel 2 30 to 100 m Medium Head Francis turbine 3 Below 30 m Low Head Kaplan (or) Francis turbine
- 22. HYDEL POWER PLANT VIDEO
- 23. HYDEL POWER PLANT VIDEO
- 25. COMPONENTS OF HYDEL POWER PLANT Water reservoir Dam Spillway Gate Pressure tunnel Surge tank Penstock Hydraulic turbine Inlet valve Draft tube Tail race level Head race level Catchment area
- 26. Availability of water Water storage capacity Available water head Accessibility of the site Distance from the load centre Type of the land of the site SELECTION OF SITE FOR A HYDROELECTRIC POWER PLANT
- 27. ADVANTAGES • Water is the cheapest source of energy • Hydel power plant is highly reliable • Life of the plant is very long • Running cost of plant is low • No fuel transportation problem • Maintenance and operation charges are very low • No ash disposal problem • Easy operation
- 28. DISADVANTAGES • Initial cost of plant is very high and more time is required for erection • Transmission losses are more and cost is high • Power generation depends on quantity of water available which in turn depends on rainfall • It takes considerably longer time for its installation, compared to thermal power plants
- 30. DIESEL POWER PLANT • Diesel power plant depend upon the diesel engine • Capacity – 2 to 50 MW • Diesel power plant is suitable for small and medium outputs • Diesel power plants can be used as stand-by plants to hydro-electric power plants and steam power plants for emergency service.
- 32. COMPONENTS OF DIESEL POWER PLANT • Diesel engine • Air filter and super charger • Engine starting system • Fuel system • Lubrication system • Cooling system • Governing system • Exhaust system
- 37. ADVANTAGES • Fuel handling is easier • The plant is smaller in size than steam or thermal power plant • There is no problem of ash disposal exists • Diesel power plants operate at high overall efficiency than steam power plant • It requires minimum labour • Plant layout is simple
- 38. DISADVANTAGES • The repair and maintenance costs are high • Diesel fuel is much more expensive than coal • The lubrication costs are high • The capacity of the diesel engine is considerably lower than thermal power plant • Life of the diesel power plants are low when compared with thermal power plants
- 39. APPLICATIONS • It is quite suitable for mobile power generation • It is used as peak load plants in combined with thermal or hydro plants • It is used as stand by plants for emergency service
- 40. GAS TURBINE POWER PLANT
- 41. GAS TURBINE POWER PLANT • Natural gas is used as fuel. • Air is compressed to a high pressure and heated by means of the flue gases. • Natural gas burns in the stream of hot air and the gases coming out are used to run the turbine Heat energy Pressure energy Mechanical energy Electrical energy
- 42. GAS TURBINE POWER PLANT • The working medium for transforming thermal energy into rotating mechanical energy is the hot combustion gas, hence the term “GAS TURBINE” • Gas turbines are also referred to as Combustion Turbines (or) Combustion gas turbines
- 43. GAS TURBINE POWER PLANT DEVICE ENERGY CONVERSION Compressor - Air Pressure energy Combustion Chamber - Pressure energy Heat energy (Air+fuel) Turbine - Heat energy Mechanical energy Generator - Mechanical energy Electrical energy
- 45. COMPONENTS OF GAS TURBINE POWER PLANT Low pressure Air compressor ( LPC) Intercooler High pressure Air compressor (HPC) Regenerator Combustion Chamber ( CC) High pressure turbine ( HPT) Low pressure turbine ( LPT) Reheating combustion chamber ( RCC)
- 46. ADVANTAGES • Natural gas is a very suitable for gas turbine plant and is easily available and cheap • Gas turbine plant is smaller in size and less weight compared to steam plant • Initial cost is low • Less maintenance cost • Simple in construction and does not require heavy foundation and buildings
- 47. DISADVANTAGES Major part of the work (i.e.,66%) developed in the turbine is used to drive the compressor. Therefore net work output of the plant is low. Therefore, overall efficiency is low Special cooling methods are required Poor part load efficiency
- 48. APPLICATIONS Gas turbine power plants are used to supply peak loads in steam or Hydel power plants It is used as standby unit for Hydel power plants It is used in aircraft and ships
- 50. NUCLEAR POWER PLANT • Uranium is used as nuclear fuel • The principle involved is nuclear fission Nuclear fission : • It is a process of splitting up the nucleus of fissionable material like uranium into two or more fragments with release of enormous amount of energy
- 51. NUCLEAR FISSION • When the nucleus of uranium 235 is bombarded with high energy neutrons. • The atom splits up into two fragments thereby releasing 2.5 neutrons and enormous amount of energy U235 + 0n1 Ba141 + Kr 92 + 2.5 0n1 + 200 MeV
- 52. NUCLEAR FISSION
- 53. NUCLEAR FISSION
- 58. Nuclear reactor • Nuclear reactor is the heart of the nuclear plant • It is a device used to produce heat • It is similar to a boiler in steam power plant • Heat is produced in the reactor due to nuclear fission of the fuel U235 • Pressure equalizer is used to maintain a constant pressure
- 59. COMPONENTS • Reactor core • fuel rod & Control rod • Moderator • Coolant • Radiation Shielding • Steam generator • Turbine • Condenser • Feed pump
- 60. REACTOR CORE • Nuclear fission reaction takes place in reactor core. • It is in the shape of right circular cylinder and consists of fuel elements, control rods, coolant and moderator
- 61. FUEL RODS & CONTROL ROD • Fuel rod of a nuclear reactor should be a fissionable material • Fuel rods of the reactor can be one or all of the following : U233 , U235 , Pu239 • Control rods are used to regulate the rate of chain reaction. • They are used to absorb the excess neutrons. • Control rods are made of boron or cadmium
- 62. MODERATORS • Moderator is used to slow down the fast moving neutrons. • The process of slowing down is called moderation or thermalizing. • Materials containing light weight atoms, Hydrogen, graphite,beryllium • Specially hydrogen are found to be most effective as moderators
- 63. COOLANT • Coolant is used to remove the intense heat produced in the reactor • Water is used as coolant and sometimes liquid sodium is also used
- 64. SHIELDING • Among the nuclear radiations produced in a reactor the α and ᵝ particles, fast neutrons, slow neutrons and ƴ rays are the harmful ones must be shielded against • Thermal shield is provided through steel lining of the reactor vessel and another shield is made of thick concrete surrounding the reactor. This is called as radiation shielding
- 65. STEAM GENERATOR • Hot coolant water leaves the reactor at the top. It flows into steam generator ( Boiler ) in the secondary circuit and transfers the heat to the feed water in the steam generator. • The feed water evaporates to become steam
- 66. TURBINE The steam produced in the steam generator is passed to the turbine. Work is done by the expansion of steam in the turbine. The turbine shaft is coupled to the generator and electricity is produced
- 67. • Condenser : – The steam coming from the turbine is passed to condenser. Steam is converted into water by circulating cold water around the condenser tubes. • Feed pump : – The feed pump pumps the condensed water from the condenser to the steam generator
- 68. ADVANTAGES • Nuclear power plant needs less space • Fuel consumption is very small • Less fuel transportation cost • Not affected by adverse weather conditions • Operation of the plant is more reliable • Less workmen is required
- 69. DISADVANTAGES • Capital cost is high • Maintenance cost is high • Radioactive wastes, if not disposed carefully have adverse effects on environment • Not suitable for varying load conditions
- 70. SELECTING SUITABLE SITE FOR NUCLEAR POWER PLANT • Distance from the load center • Availability of cooling water • Distance from populated area • Radioactive waste disposal facility
- 75. PUMPS • Pump is a hydraulic machine driven by a motor • The pump converts the mechanical energy developed by reciprocating or rotation motion of the pump into hydraulic energy. • The hydraulic energy is in the form of pressure energy.This pressure energy is converted into potential energy, as the liquid is lifted from a lower level to higher level
- 76. USES OF PUMPS • Used to feed the water into the boiler ( called feed pump) in power plants • Used to circulate water in the condenser ( called condensate pump) for condensing steam in power plants • Used to force the lubricating oil into the moving parts or rotating parts of I.C engines
- 77. There are two main categories of pump: Rotodynamic pumps. Positive displacement pumps. Diaphragm Piston Plunger ReciprocatingRotary Mixed flow Gear Lobe Sliding Vane Screw Axial flow Centrifugal Rotodynamic Turbine Positive displacement PUMP 2
- 78. Centrifugal pump • Centrifugal pump is a hydraulic machine with a rotating part called impeller. • In this pump, mechanical energy is converted into pressure energy by means of centrifugal force acting on the liquid. • The liquid enters the pump at the peripheral hub and leaves the casing radially
- 80. VOLUTE CASING
- 81. VORTEX CASING
- 82. DIFFUSER CASING
- 83. RECIPROCATING PUMP • Pumps are used to increase the energy level of water by virtue of which it can be raised to a higher level. • Reciprocating pumps are positive displacement pump, i.e. initially, a small quantity of liquid is taken into a chamber and is physically displaced and forced out with pressure by a moving mechanical elements. • The use of reciprocating pumps is being limited these days and being replaced by centrifugal pumps
- 84. Main components • A reciprocation pumps consists of a plunger or a piston that moves forward and backward inside a cylinder with the help of a connecting rod and a crank. The crank is rotated by an external source of power. • The cylinder is connected to the sump by a suction pipe and to the delivery tank by a delivery pipe. • At the cylinder ends of these pipes, non-return valves are provided. A non-return valve allows the liquid to pass in only one direction. • Through suction valve, liquid can only be admitted into the cylinder and through the delivery valve, liquid can only be discharged into the delivery pipe.
- 85. Single acting reciprocating pump
- 86. Single acting reciprocating pump
- 90. Comparison of Centrifugal and Reciprocating Pumps Centrifugal Pumps Reciprocating Pumps 1. Steady and even flow 1. Intermittent and pulsating flow 2. For large discharge, small heads 2. For small discharge, high heads. 3. Can be used for viscous fluids e.g. oils, muddy water. 3. Can handle pure water or less viscous liquids only otherwise valves give frequent trouble. 4. Low initial cost 4. High initial cost. 5. Can run at high speed. Can be coupled directly to electric motor. 5. Low speed. Belt drive necessary. 6. Low maintenance cost. Periodic check up sufficient. 6. High maintenance cost. Frequent replacement of parts. 7. Compact less floors required. 7. Needs 6-7 times area than for centrifugal pumps. 8. Low head pumps have high efficiency 8. Efficiency of low head pumps as low as 40 per cent due to the energy losses. 9. Uniform torque 9. Torque not uniform. 10. Simple constructions. Less number of spare parts needed 10. Complicated construction. More number of spare parts needed.
- 91. Air vessels
- 92. Purposes of Air vessels (i) The flow fluctuation is reduced and a uniform flow is obtained. (ii) The friction work is reduced. (iii) The acceleration head is reduced considerably. (iv) Enables the use of higher speeds.
- 93. STEAM TURBINES • A steam turbine is a mechanical device that extracts thermal energy from pressurised steam and converts it into useful mechanical work. • A steam turbine is a prime mover which converts heat energy in the steam into mechanical work. • The main parts of a steam turbine are nozzle, rotor and rotor blades
- 94. PRINCIPLE • The enthalpy of the steam is first converted into kinetic energy in nozzles. • The high velocity steam impinges on the curved blades and the direction of flow of steam is changed. • The change in flow direction of steam exerts a force on the blades fixed on the rotor and the rotor starts rotating producing power
- 95. Classification of steam turbines • Impulse turbine • Reaction turbine
- 96. Impulse turbine • In impulse turbines, the steam coming out at a very high velocity through the nozzle impinges on the blades fixed on the periphery of the rotor • The blades change the direction of steam flow without changing its pressure. • The resulting force causes the rotation of the turbine shaft.
- 97. Impulse turbine
- 98. Reaction turbine
- 99. Reaction turbine