BHELreport
- 1. BHARAT HEAVY ELECTRICALS LIMITED ELECTRONICS DIVISION A Report on Power Plant Station,Automation & Control Systems
- 2. Introduction to BHEL BHEL Electronics Division (EDN) along with Electronics Systems Division (ESD-part of EDN), situated at Bangalore is a leading supplier of new Generation Power Plant Automation and Control Systems. The Electronics Division has also emerged as a leading player in the field of power transmission and distribution, industry, transportation and non-conventional energy sources. The state-of-the-art equipment and systems manufactured, meet the demanding requirements of both the national and international markets in terms of technical specification and quality. The Division has established references both in India and overseas by successful installation of Power PlantAutomation and Photovoltaic systems. Besides providing unified solutions for various control system applications, the Division proudly holds the largest market share for Power Plant Automation systems in India. BHEL At Present Power Plant and Industries: Advance control and automation equipment and systems for power plants and process industries Transmission and Distribution: Providing solutions for improving the efficiency, quality of power and system stability Transportation: IGBT based Traction Drive Systems for Locomotives Non-conventional energy: Photovoltaic cells, Modules, MW size Power Plants, Space Grade Solar Panels, Space Batteries and provide system level solutions Product excellence, commitment to Quality, relentless efforts and unwavering commitment to in-house solutions, along with Technical collaborations with international leaders, strategic investment in new ultra- modern facilities and capacity expansion, have been the main factors for the rapid growth of the Division. Certifications ISO 9001 : Quality systems and procedures ISO 14001: Environmental Management System Certification ISO 27001: Information Security Management System(ISMS) Standard OHSAS 18001: Occupational Health and Safety Assessment Series Vision BHEL’s vision envisages further growth for EDN, transforming the unit into a world class enterprise, providing comprehensive solutions to customers, while exploring new frontiers in software and hardware applications to fulfil the growing needs and expectations of the global market. The Company has also joined the United Nations “Global Compact” and has committed to support the set of core values enshrined in its principles in the area of human rights, labour standards, environment and anti-corruption.
- 3. EDN – Product Panorama THERMAL POWER PLANTS Steam Generators, Steam Turbines, Turbo Generators along with regenerative feed cycle up to 800 MW capacities for fossil-fuel, and combined-cycle applications, capability to design and manufacture Steam Generators, steam turbines with supercritical steam cycle parameters and matching Turbo Generators of up to 1000 MW unit size. Condensers, Condensate Extraction Pumps, Boiler Feed Pumps, Valves and Heat Exchangers meeting above requirement of TG Sets up to 1000 MW. NUCLEAR POWER PLANTS Steam generator & Turbines and matching Turbo-Generators, Condensers up to 700 MW capacity. Heat exchangers Pressure vessel Reactor vessels GAS-BASED POWER PLANTS Gas turbines and matching generators ranging from 25 to 292 MW (ISO) rating. Gas turbine-based co-generation and combined-cycle systems for industry and utility applications. BOILERS Steam generators for utilities, ranging from 30 to 800 MW capacity, using coal, lignite, oil, natural gas or a combination of these fuels; capability to manufacture boilers with supercritical parameters up to 1000 MW unit size. Steam generators for industrial applications, ranging from 40 to 450 tonne/hour capacity, using coal, natural gas, industrial gases, biomass, lignite, oil, Bagasse or a combination of these fuels. Pulverized fuel fired boilers Stoker boilers Bubbling fluidized bed combustion (BFBC) boilers. Circulating fluidized bed combustion (CFBC) boilers up to 250 MW. Heat-recovery steam generators (HRSG). Chemical recovery boilers for paper industry, ranging from capacity of 100 to 1000 tonne/day of dry solids. CONDENSER AND HEAT EXCHANGERS Surface Condenser: 236 MW & 700 MW for Nuclear power plants 12.5 MW Marine applications Industrial Condensers Feed Water Heaters (HP Heaters, LP Heaters, Drain Coolers etc.) Thermal -07 to 500 MW (sub-critical) & 300-800 MW (super critical with single stream) Nuclear 236 MW, 500 MW and 700 MW rating Moisture Separator &Reheater(MSR): 236 MW, 500 MW & 700 MW Nuclear sets Live Steam Reheater (LSR): 500 MW FBR Nuclear sets Auxiliary Heat Exchangers for Turbo and Hydro Generators : Air Coolers (Frame & Tube Type) Oil Coolers (Shell & Tube Type and Plug In Type)
- 4. Hydrogen Coolers (Frame & Tube Type) Auxiliary Heat Exchangers for Transformers : Oil Coolers (Shell & Tube Type Single Tube or Concentric Double Tube Type) (Frame & Tube Type) Auxiliary Heat Exchangers for General Application Water - Water Coolers (Shell & Tube Type) Industrial Heat Exchangers for Refineries, Petro-Chemicals & Fertilizers industries. Butterfly Valves( Fabricated/ cast body & door) Flash Tanks for thermal & nuclear sets Service Tanks, Storage Tanks & Pressure vessels for Thermal, Nuclear sets of all ratings & industrial applications CS/SS/Non-ferrous shell and tube heat exchangers and pressure vessels (For all applications irrespective of rating) Air-cooled heat exchangers for GTG upto Fr-9 FE, and Compressor applications of all ratings Steam jet air ejectors for all condensers upto 150 MW Deaerators from 7 MW to 800 MW Gland steam condensers 7 MW to 150 MW Gas coolers for all possible compressor applications Oil coolers- STG upto 150 MW, GTG upto Fr-9 F E, Generator Air coolers upto 150 MW STG and GTG up to 9 FA PUMPS Pumps for various applications to suit utilities up to a capacity of 1000 MW. Boiler feed pumps (motor or steam turbine driven). Boiler feed booster pumps. Condensate extraction pumps. Circulating water pumps. (Also known as-Cooling water Pumps) AUTOMATION AND CONTROL SYSTEMS Steam Generator/ Boiler Controls Steam Turbine Controls Boiler Feed Pump (BFP) Drive Turbine Control Station Control and Instrumentation/ DCS Offsite/Off base controls/ Balance of Plant Controls Ash handling Coal Handling Water System Mill Reject System Condensate on-line tube cleaning system Gas Booster Compressor Hydro Power Plant Control System Gas Turbine Control System Nuclear Power Plant Turbine & Secondary Cycle control system Power block of solar thermal power plant Industrial Automation Sub-Station Automation (SAS) and Supervisory Control & data Acquisition System (SCADA) Electrical Control System (ECS) for Refineries Energy Management System (EMS) for Power Plant
- 5. POWER ELECTRONICS Excitation system AC Drive System Static Starters Induction Heating Equipment TRANSMISSION SYSTEM CONTROL High Voltage Direct Current (HVDC) system Flexible AC Transmission system (FACTS) Fixed series compensation (FCS)/ Thyristor controlled series compensation (TCSC) Static VAR Compensation (SVC) System Controlled Shunt Reactor (CSR) Static Compensator (STATCOM) POWER SEMICONDUCTOR DEVICES Diodes- Ranging from 1400-4400V/250-2000A Thyristors- Ranging from 1400-7000V/150-4950A Rotating Diodes for Turbo generators. SOLAR PHOTOVOLTAICS Mono/ Multi Crystalline Cells (125 and 156 mm) Mono/ Multi Crystalline Modules (40 to 300 Wp) PV Systems: Grid Interactive, Hybrid and stand alone PV power plants Space grade solar panels Space Quality Batteries DEFENCE ELECTRONICS Integrated Platform Management system (IPMS) Integrated Bridge System (IBS) Machinery Control Room (MCR) Simulator Training Simulator for Vehicles, platforms, radars, weapons, missiles and CBT for all defence and para-military forces Weapon Fire control system, Avionics, radio communication Products, Electronic warfare system and Early Warning Systems. Gun control System for Main Battle Tanks (MBT)
- 6. Thermal PowerPlant Layout At present 54.09% or 93918.38 MW (Data Source CEA, as on 31/03/2011) of total electricity production in India is from Coal Based Thermal Power Station. A coal based thermal power plant converts the chemical energy of the coal into electrical energy. This is achieved by raising the steam in the boilers, expanding it through the turbine and coupling the turbines to the generators which converts mechanical energy into electrical energy. A typical Thermal Power Station Operates on a Cycle which is shown below. A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. The greatest variation in the design of thermal power stations is due to the different fossil fuel resources generally used to heat the water. Some prefer to use the term energy centre because such facilities convert forms of heatenergy into electrical energy. Certain thermal power plants also are designed to produce heat power. Globally, fossil-fuel power stations produce a large part of man-made CO2 emissions to the atmosphere, and efforts to reduce these are varied and widespread.
- 7. Theory of Thermal PowerPlant Station The theory of thermal power station or working of thermal power station is very simple. A power generation plant mainly consists of alternator runs with help of steam turbine. The steam is obtained from high pressure boilers. Generally in India, bituminous coal, brown coal and peat are used as fuel of boiler. The bituminous coal is used as boiler fuel has volatile matter from 8 to 33 % and ash content 5 to 16 %. To increase the thermal efficiency, the coal is used in the boiler in powder form. In coal thermal power plant, the steam is produced in high pressure in the steam boiler due to burning of fuel (pulverized coal) in boiler furnaces. This steam is further supper heated in a super heater. This supper heated steam then enters into the turbine and rotates the turbine blades. The turbine is mechanically so coupled with alternator that its rotor will rotate with the rotation of turbine blades. After entering in turbine the steam pressure suddenly falls and corresponding volume of the steam increases. After imparting energy to the turbine rotor the steam passes out of the turbine blades into the condenser. In the condenser the cold water is circulated with the help of pump which condenses the low pressure wet steam. This condensed water is further supplied to low pressure water heater where the low pressure steam increases the temperature of this feed water, it is again heated in high pressure. For better understanding we furnish every step of function of a thermal power station as follows, 1) First the pulverized coal is burnt into the furnace of steam boiler. 2) High pressure steam is produced in the boiler. 3) This steam is then passed through the super heater, where it further heated up. 4) This supper heated steam is then entered into a turbine at high speed. 5) In turbine this steam force rotates the turbine blades that means here in the turbine the stored potential energy of the high pressured steam is converted into mechanical energy. 6) After rotating the turbine blades, the steam has lost its high pressure, passes out of turbine blades and enters into a condenser. 7) In the condenser the cold water is circulated with help of pump which condenses the low pressure wet steam. 8) This condensed water is then further supplied to low pressure water heater where the low pressure steam increases the temperature of this feed water, it is then again heated in a high pressure heater where the high pressure of steam is used for heating. 9) The turbine in thermal power station acts as a prime mover of the alternator. Components of Thermal PowerPlantStation Coal Preparation Steam Generator/Boiler Boiler drum Steam Turbines Condenser Boiler Feed Pump Cooling Towers Generator Electrostatic Precipitator
- 8. Smoke stack CoalPreparation Fuel preparation system: In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder, so that coal will undergo complete combustion during combustion process Pulveriser pulveriser is a mechanical device for the grinding of many different types of materials. For example, they are used to pulverize coal for combustion in the steam-generating furnaces of fossil fuel power plants. Types of Pulverisers: Ball and Tube mills; Ring and Ball mills; MPS; Ball mill; Demolition Dryers: they are used in order to remove the excess moisture from coal mainly wetted during transport. As the presence of moisture will result in fall in efficiency due to incomplete combustion and also result in CO emission. Magnetic separators: coal which is brought may contain iron particles. These iron particles may result in wear and tear. The iron particles may include bolts, nuts wire fish plates etc. so these are unwanted and so are removed with the help of magnetic separators. The coal we finally get after these above process are transferred to the storage site. Purpose of fuel storage is two – Fuel storage is insurance from failure of normal operating supplies to arrive. Storage permits some choice of the date of purchase, allowing the purchaser to take advantage of seasonal market conditions. Storage of coal is primarily a matter of protection against the coal strikes, failure of the transportation system & general coal shortages. There are two types of storage: 1. Live Storage (boiler room storage): storage from which coal may be withdrawn to supply combustion equipment with little or no remanding is live storage. This storage consists of about 24 to 30 hrs. of coal requirements of the plant and is usually a covered storage in the plant near the boiler furnace. The live storage can be provided with bunkers & coal bins. Bunkers are enough capacity to store the requisite of coal. From bunkers coal is transferred to the boiler grates. 2. Dead storage– stored for future use. Mainly it is for longer period of time, and it is also mandatory to keep a backup of fuel for specified amount of days depending on the reputation of the company and its connectivity.There are many forms of storage some of which are – 1. Stacking the coal in heaps over available open ground areas. 2. As in (I). But placed under cover or alternatively in bunkers. 3. Allocating special areas & surrounding these with high reinforced concerted retaking walls. Feedwaterheating The boiler feed water used in the steam boiler is a means of transferring heat energy from the burning fuel to the mechanical energy of the spinning steam turbine. The total feed water consists of recirculated condensate water and purified makeup water. Because the metallic materials it contacts are subject to corrosion at high temperatures and pressures, the makeup water is highly purified before use. A system of water softeners and ion exchange demineralizers produces water so pure that it coincidentally becomes an electrical insulator, with conductivity in the range of 0.3–1.0 micro Siemens per centimetre. The makeup water in a 500 MW plant amounts to perhaps 120 US gallons per minute (7.6 L/s)to replace water drawn off from the boiler drums for water purity management, and to also offset the small losses from steam leaks in the system. Boilerand Auxiliaries The boiler is a rectangular furnace about 50 feet (15 m) on a side and 130 feet (40 m) tall. Its walls are made of a web of high pressure steel tubes about 2.3 inches (58 mm) in diameter.
- 9. Pulverized coal is air-blown into the furnace through burners located at the four corners, or along one wall, or two opposite walls, and it is ignited to rapidly burn, forming a large fireball at the centre. The thermal radiationof the fireball heats the water that circulates through the boiler tubes near the boiler perimeter. The water circulation rate in the boiler is three to four times the throughput. As the water in the boiler circulates it absorbs heat and changes into steam. It is separated from the water inside a drum at the top of the furnace. The saturated steam is introduced into superheat pendant tubes that hang in the hottest part of the combustion gases as they exit the furnace. Here the steam is superheated to 1,000 °F (540 °C) to prepare it for the turbine. Boiler furnace and steam drum The water enters the boiler through a section in the convection pass called the economizer. From the economizer it passes to the steam drum and from there it goes through down comers to inlet headers at the bottom of the water walls. From these headers the water rises through the water walls of the furnace where some of it is turned into steam and the mixture of water and steam then re-enters the steam drum. This process may be driven purely by natural circulation (because the water is the down comers is denser than the water/steam mixture in the water walls) or assisted by pumps. In the steam drum, the water is returned to the down comers and the steam is passed through a series of steam separators and dryers that remove water droplets from the steam. The dry steam then flows into the superheater coils. The boiler furnace auxiliary equipment includes coal feed nozzles and igniter guns, soot blowers, water lancing and observation ports (in the furnace walls) for observation of the furnace interior. Furnace explosions due to any accumulation of combustible gases after a trip-out are avoided by flushing out such gases from the combustion zone before igniting the coal. The steam drum (as well as the super heater coils and headers) have air vents and drains needed for initial start- up Superheater Fossil fuel power plants often have a superheater section in the steam generating furnace. The steam passes through drying equipment inside the steam drum on to the superheater, a set of tubes in the furnace. Here the steam picks up more energy from hot flue gases outside the tubing and its temperature is now superheated above
- 10. the saturation temperature. The superheated steam is then piped through the main steam lines to the valves before the high pressure turbine. The amount of superheat added to the steam is influenced by the location, arrangement, and amount of superheater surface installed, as well as the rating of the boiler. The superheater may consist of one or more stages of tube banks arranged to effectively transfer heat from the products of combustion.Superheaters are classified as convection, radiant or combination of these. Economizer It is located below the LPSH in the boiler and above pre heater. It is there to improve the efficiency of boiler by extracting heat from flue gases to heat water and send it to boiler drum. Flue gases coming out of the boiler carry lot of heat.Function of economiser is to recover some of the heat from the heat carried away in the flue gases up the chimney and utilize for heating the feed water to the boiler.It is placed in the passage of flue gases in between the exit from the boiler and the entry to the chimney.The use of economiser results in saving in coal consumption , increase in steaming rate and high boiler efficiency but needs extra investment and increase in maintenance costs and floor area required for the plant.This is used in all modern plants.In this a large number of small diameter thin walled tubes are placed between two headers.Feed water enters the tube through one header and leaves through the other.The flue gases flow outside the tubes usually in counter flow. Advantages of Economizer include 1) Fuel economy: – used to save fuel and increase overall efficiency of boiler plant. 2) Reducing size of boiler: – as the feed water is preheated in the economiser and enter boiler tube at elevated temperature. The heat transfer area required for evaporation reduced considerably. Air Preheater The remaining heat of flue gases is utilised by air preheater.It is a device used in steam boilers to transfer heat from the flue gases to the combustion air before the air enters the furnace. Also known as air heater; air-heating system. It is not shown in the lay out.But it is kept at a place near by where the air enters in to the boiler. The purpose of the air preheater is to recover the heat from the flue gas from the boiler to improve boiler efficiency by burning warm air which increases combustion efficiency, and reducing useful heat lost from the flue. As a consequence, the gases are also sent to the chimney or stack at a lower temperature, allowing simplified design of the ducting and stack. It also allows control over the temperature of gases leaving the stack (to meet emissions regulations, for example).After extracting heat flue gases are passed to electrostatic precipitator. Reheater Power plant furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go inside the reheater tubes to pick up more energy to go drive intermediate or lower pressure turbines. Air path External fans are provided to give sufficient air for combustion. The Primary air fan takes air from the atmosphere and, first warming it in the air preheater for better combustion, injects it via the air nozzles on the furnace wall. The induced draft fan assists the FD fan by drawing out combustible gases from the furnace, maintaining a slightly negative pressure in the furnace to avoid backfiring through any closing.
- 11. SteamTurbines The turbine generator consists of a series of steam turbines interconnected to each other and a generator on a common shaft. There is a high pressure turbine at one end, followed by an intermediate pressure turbine, two low pressure turbines, and the generator. As steam moves through the system and loses pressure and thermal energy it expands in volume, requiring increasing diameter and longer blades at each succeeding stage to extract the remaining energy. The entire rotating mass may be over 200 metric tons and 100 feet (30 m) long. It is so heavy that it must be kept turning slowly even when shut down (at 3 rpm) so that the shaft will not bow even slightly and become unbalanced. This is so important that it is one of only five functions of blackout emergency power batteries on site. Other functions are emergency lighting, communication, station alarms and turbo generator lube oil. Superheated steam from the boiler is delivered through 14–16-inch (360–410 mm) diameter piping to the high pressure turbine where it falls in pressure to 600 psi (4.1 MPa) and to 600 °F (320 °C) in temperature through the stage. It exits via 24–26-inch (610–660 mm) diameter cold reheat lines and passes back into the boiler where the steam is reheated in special reheat pendant tubes back to 1,000 °F (540 °C). The hot reheat steam is conducted to the intermediate pressure turbine where it falls in both temperature and pressure and exits directly to the long- bladed low pressure turbines and finally exits to the condenser. The generator, 30 feet (9 m) long and 12 feet (3.7 m) in diameter, contains a stationary stator and a spinning rotor, each containing miles of heavy copper conductor—no permanent magnets here. In operation it generates up to 21,000 amperes at 24,000 voltsAC (504 MWe) as it spins at either 3,000 or 3,600 rpm, synchronized to the power grid. The rotor spins in a sealed chamber cooled with hydrogen gas, selected because it has the highest known heat transfer coefficient of any gas and for its low viscosity which reduces windage losses. This system requires special handling during start-up, with air in the chamber first displaced by carbon dioxide before filling with hydrogen. This ensures that the highly explosive hydrogen–oxygen environment is not created. The power grid frequency is 60 Hz across North America and 50 Hz in Europe, Oceania, Asia (Korea and parts of Japan are notable exceptions) and parts of Africa. The desired frequency affects the design of large turbines, since they are highly optimized for one particular speed. The electricity flows to a distribution yard where transformers increase the voltage for transmission to its destination. The steam turbine-driven generators have auxiliary systems enabling them to work satisfactorily and safely. The steam turbine generator being rotating equipment generally has a heavy, large diameter shaft. The shaft therefore requires not only supports but also has to be kept in position while running. To minimize the frictional resistance to the rotation, the shaft has a number of bearings. The bearing shells, in which the shaft rotates, are lined with a low friction material like Babbitt metal. Oil lubrication is provided to further reduce the friction between shaft and bearing surface and to limit the heat generated.
- 12. Condenser Steam after rotating steam turbine comes to condenser.Condenser refers here to the shell and tube heat exchanger (or surface condenser) installed at the outlet of every steam turbine in Thermal power stations of utility companies generally. These condensers are heat exchangers which convert steam from its gaseous to its liquid state, also known as phase transition. In so doing, the latent heat of steam is given out inside the condenser. Where water is in short supply an air cooled condenser is often used. An air cooled condenser is however significantly more expensive and cannot achieve as low a steam turbine backpressure (and therefore less efficient) as a surface condenser. The purpose is to condense the outlet (or exhaust) steam from steam turbine to obtain maximum efficiency and also to get the condensed steam in the form of pure water, otherwise known as condensate, back to steam generator or (boiler) as boiler feed water. Condensers are classified as I. Jet condensers or contact condensers II. Surface condensers In jet condensers the steam to be condensed mixes with the cooling water and the temperature of the condensate and the cooling water is same when leaving the condenser; and the condensate can't be recovered for use as feed water to the boiler; heat transfer is by direct conduction. In surface condensers there is no direct contact between the steam to be condensed and the circulating cooling water. There is a wall interposed between them through heat must be convectively transferred.The temperature of the condensate may be higher than the temperature of the cooling water at outlet and the condensate is recovered as feed water to the boiler.Both the cooling water and the condensate are separately with drawn.Because of this advantage surface condensers are used in thermal power plants.Final output of condenser is water at low temperature is passed to high pressure feed water heater,it is heated and again passed as feed water to the boiler.Since we are passing water at high temperature as feed water the temperature inside the boiler does not decrease and boiler efficiency also maintained. Boilerfeed Pump Boiler feed pump is a multi-stage pump provided for pumping feed water to economiser. BFP is the biggest auxiliary equipment after Boiler and Turbine. It consumes about 4 to 5 % of total electricity generation.
- 13. Cooling Towers The condensate (water) formed in the condenser after condensation is initially at high temperature.This hot water is passed to cooling towers.It is a tower- or building-like device in which atmospheric air (the heat receiver) circulates in direct or indirect contact with warmer water (the heat source) and the water is thereby cooled (see illustration). A cooling tower may serve as the heat sink in a conventional thermodynamic process, such as refrigeration or steam power generation, and when it is convenient or desirable to make final heat rejection to atmospheric air. Water, acting as the heat-transfer fluid, gives up heat to atmospheric air, and thus cooled, is recirculated through the system, affording economical operation of the process. Two basic types of cooling towers are commonly used. One transfers the heat from warmer water to cooler air mainly by an evaporation heat-transfer process and is known as the evaporative or wet cooling tower. Evaporative cooling towers are classified according to the means employed for producing air circulation through them:atmospheric, natural draft, and mechanical draft. The other transfers the heat from warmer water to cooler air by a sensible heat-transfer process and is known as the non-evaporative or dry cooling tower. Non-evaporative cooling towers are classified as air-cooled condensers and as air-cooled heat exchangers, and are further classified by the means used for producing air circulation through them. These two basic types are sometimes combined, with the two cooling processes generally used in parallel or separately, and are then known as wet-dry cooling towers. Evaluation of cooling tower performance is based on cooling of a specified quantity of water through a given range and to a specified temperature approach to the wet-bulb or dry-bulb temperature for which the tower is designed. Because exact design conditions are rarely experienced in operation, estimated performance curves are frequently prepared for a specific installation, and provide a means for comparing the measured performance with design conditions. Generator Generator or Alternator is the electrical end of a turbo-generator set. It is generally known as the piece of equipment that converts the mechanical energy of turbine into electricity. The generation of electricity is based on the principle of electromagnetic induction. Most alternators use a rotating magnetic field. Different geometries - such as a linear alternator for use with stirling engines - are also occasionally used. In principle, any AC generator can be called an alternator, but usually the word refers to small rotating machines driven by automotive and other internal combustion engines. The generator voltage for modern utility-connected generators ranges from 11 kV in smaller units to 22 kV in larger units. The generator high-voltage leads are normally large aluminium channels because of their high current as compared to the cables used in smaller machines. They are enclosed in well-grounded aluminium bus ducts and are supported on suitable insulators. The generator high-voltage leads are connected to step-up transformers for connecting to a high-voltage electrical substation (usually in the range of 115 kV to 765 kV) for further transmission by the local power grid.
- 14. The necessary protection and metering devices are included for the high-voltage leads. Thus, the steam turbine generator and the transformer form one unit. Smaller units may share a common generator step-up transformer with individual circuit breakers to connect the generators to a common bus. Electrostatic precipitator It is a device which removes dust or other finely divided particles from flue gases by charging the particles inductively with an electric field, then attracting them to highly charged collector plates. Also known as precipitator. The process depends on two steps. In the first step the suspension passes through an electric discharge (corona discharge) area where ionization of the gas occurs. The ions produced collide with the suspended particles and confer on them an electric charge. The charged particles drift toward an electrode of opposite sign and are deposited on the electrode where their electric charge is neutralized. The phenomenon would be more correctly designated as electrodeposition from the gas phase. The use of electrostatic precipitators has become common in numerous industrial applications. Among the advantages of the electrostatic precipitator are its ability to handle large volumes of gas, at elevated temperatures if necessary, with a reasonably small pressure drop, and the removal of particles in the micrometre range. Some of the usual applications are: (1) Removal of dirt from flue gases in steam plants; (2) Cleaning of air to remove fungi and bacteria in establishments producing antibiotics and other drugs, and in operating rooms; (3) Cleaning of air in ventilation and air conditioning systems; (4) Removal of oil mists in machine shops and acid mists in chemical process plants; (5) Cleaning of blast furnace gases; (6) Recovery of valuable materials such as oxides of copper, lead, and tin; and (7) Separation of rutile from zirconium sand. Smoke stack A chimney is a system for venting hot flue gasesor smoke from a boiler, stove, furnace or fireplace to the outsideatmosphere. They are typically almost vertical to ensure that the hot gases flow smoothly, drawing air into the combustion through the chimney effect (also known as the stack effect). The space inside a chimney is called a flue. Chimneys may be found in buildings, steam locomotives and ships. The term funnel is generally used for ship chimneys and sometimes used to refer to locomotive chimneys.Chimneys are tall to increase their draw of air for combustion and to disperse pollutants in the flue gases over a greater area so as to reduce the pollutant concentrations in compliance with regulatory or other limits. Monitoring and alarm system Most of the power plant operational controls are automatic. However, at times, manual intervention may be required. Thus, the plant is provided with monitors and alarm systems that alert the plant operators when certain operating parameters are seriously deviating from their normal range. Battery-supplied emergencylighting and communication A central battery system consisting of lead acid cell units is provided to supply emergency electric power, when needed, to essential items such as the power plant's control systems, communication systems, turbine lube oil pumps, and emergency lighting. This is essential for a safe, damage-free shutdown of the units in an emergency situation. Advantages of coal based thermal Power Plant They can respond to rapidly changing loads without difficulty A portion of the steam generated can be used as a process steam in different industries
- 15. Steam engines and turbines can work under 25 % of overload continuously Fuel used is cheaper Cheaper in production cost in comparison with that of diesel power stations Disadvantages of coal based thermal Power Plant Maintenance and operating costs are high Long time required for erection and putting into action A large quantity of water is required Great difficulty experienced in coal handling Presence of troubles due to smoke and heat in the plant Unavailability of good quality coal Maximum of heat energy lost Problem of ash removing Efficiency of Thermal powerstation The overall efficiency of a thermal power station or plant varies from 20% to 26% and it depends upon plant capacity. Installed plant capacity Average overall thermal efficiency 1MW 4% 1MW to 10MW 12% 10MW to 50MW 16% 50MW to 100MW 24% above 100MW 27% Thermal PowerPlant Location A thermal power station or thermal power plant has ultimate target to make business profit. Hence for optimizing the profit, the location of the station is much important factor. Power generation plant location plays an optimizing part in the economy of the station.Many points to be considered to decide the best optimized location of the power plant. 1) The electric power generation plant must be constructed at such a place where the cost of land is quite reasonable. 2) The land should be such that the acquisition of private property must be minimum. 3) A large quantity of cooling water is required for the condensers etc of thermal power generation plant, hence the plant should preferably situated beside big source of natural water source such as big river. 4) Availability of huge amount of fuel at reasonable cost is one of the major criterions for choosing plant location. 5) The plant should be established on plane land. 6)The soil should be such that it should provide good and firm foundation of plant and buildings. 7) The thermal power plant location should not be very nearer to dense locality as there are smoke, noise steam, water vapours etc. 8) There must be ample scope of development of future demand.
- 16. 9) Place for ash handling plant for thermal power station should also be available very nearby. 10) Very tall chimney of power station should not obstruct the traffics of air ships. PowerPlant Automation Power-system automation is the act of automatically controlling the power system via instrumentation and control devices. Substation automation refers to using data fromIntelligent electronic devices (IED), control and automation capabilities within the substation, and control commands from remote users to control power-system devices. Automation for Hydro Power Plants/Irrigation Projects comprising of: Computerised control and Monitoring Systems Unit Control Boards Switchyard Control Boards Automatic Plant start-up/shut-down System Dam Controls Typical display on HMI Work Station Important Achievements Export of Hydel Power Plant controls for project in Bhutan, Taiwan, Nepal, Vietnam, Tajikistan, Afghanistan and Republic of Rewanda Excitation system has been designed, supplied and commissioned in a record time of one month to restore the flood affected Power plant for APGENCO Srisailam 7X110 MW HEP
- 17. Performance Analysis, Diagnosticsand Optimisation(PADO) BHEL-EDN offers PADO, a customized software based Performance Analysis, Diagnostics and Optimisation Package, working on a client-server environment for Power Plants. The PADO Package can be proposed and configured in following function-wise modules to suit project requirements of sub-critical and super-critical utilities: Performance Analysis and Monitoring System and Performance Optimisation System and Performance Diagnostics Boiler Performance Optimisation System(BPOS) including intelligent soot blowing Intelligent Water and Steam Chemistry Management System Emission analysis and Monitoring Lifetime Monitoring of Boiler Thick walled components Optimisation Package Display Screen SolarPhotovoltaic Systems The Electronics Division of BHEL where the Photovoltaic modules are manufactured has been involved in the design and manufacture of sophisticated electronics and power semiconductors since 1978. Based on this expertise, BHEL commenced manufacturing of Solar Photovoltaic cells and modules from 1983. The Solar Cells and Solar PV Modules are manufactured in the State of the Art manufacturing line at Bangalore. Application Solar PV Power Plants Power packs for Banks/Retail fuel Outlets/Rural telephone Exchanges, etc. Water Pumping System Home Lighting Street Lighting
- 18. PowerSemiconductorDevices BHEL commenced manufacture of power semiconductor devices in the year 1978, to cater to the growing requirements of power electronic systems and controls in India. The semiconductor devices from BHEL, consisting of thyristors, diodes and power modules, have earned a reputation for high reliability and quality and are also exported to other countries. These devices are manufactured in a state-of-the-art fabrication facility having diffusion, alloying, encapsulation and testing equipment and this centre is the first in India to have been accredited with ISO 9001 and ISO 14000 certification among semiconductor product segment. BHEL-make devices are widely used in a variety of applications such as High Current Rectifiers, UPS & Battery Chargers, Industrial & Traction Equipment, High Speed Exciters of Turbo-generators and HVDC transmission systems. Diodes and Thyristors Power Semiconductor Diodes in the range of 1400-4400V/250-2000A and Power Thyristors in the range of 1400-7000V/150-4950A are manufactured and supplied to various market segment such as Power Generation Transmission, Industrial Applications, Traction system etc. EDN – Infrastructure Control Equipment Fabrication CNC Turret Punch,Turret with 45 stations, capable of handling sheets upto 2500 mm x 1250 mm with repositioning CNC Hydraulic Press Brake 150 T capacity CNC Lathe with Siemens 840D controller CNC Turret Punch Machine Lathe with Bar Feeder
- 19. Control Equipment Main Assembly Multiple shop-floors with an aggregate area of 6900 m2 , many of them air-conditioned Total production capacity of about 5000 cubicles per annum Dedicated shop-floor with EOT crane of 5 Ton capacity for Power-convertors used in locomotives Automatic wire cutting, stripping and crimping machines Main Assembly Control Equipment System Testing Air-conditioned test area of approximately 2500 m2 Capacity to line up and test upto 600 cubicles at a time across 5 test shop-floors Partial Discharge Test upto 50KV on HV circuits Sequence-of-event recording for DCS upto 128 channels Innovation simulation software tools and test-programs for control logic validation of DCS Conclusion In its quest to be a world-class Engineering Enterprise, committed to enhancing stakeholder values, BHEL has been practicing International Standards of Quality in its products, Systems and Services through a comprehensive Quality policy. BHEL-EDN has always been striving to be a good cooperative citizen, striving to create environment- friendly atmosphere through greeneries and eco-friendly business practices. With the objective of developing young engineers from the rural belt of the country, BHEL has been providing them with in-depth professional training. .