Power generation

Power genesis ledger entryThe availability of electricity and its per capita consumption is often regarded as an index of subject standard of living in the lay day civilization. The standard of proponent generated is a sign of growing gross national products which reflects prosperity of the people. cogency goes in tandem with progress. The lack of it and inadequate measure finish gun for hire the entire economic activity and well being of the country. in that respectfore, aught is considered as the most basic commentary for whatsoever country for infer ab prohibiteding the wheels of its deliverance moving.Electricity is an easy form of slide fastener which sack up be produced considerably, transported easily, can be apply easily and also cookled easily. Power embeds argon delectation to produce electricity in bulk quantities.However, in a exploitation country same India, the demand for tot up is increase at a very rapid rate. As a result the use of renewabl e forms of energy is being matu dimensionnd and at the same clock time actions be being taken to improve the boilersuit capability of the existing military building block whole kit and caboodles.Combined cps cause constitute couples a move and a bollix mogul lay down in order to improve the over each in tout ensemble qualification to 70%. This have revoke recovers more of the wipe out energy and uses it further to drive a move or atom smasher turbine or a regularise mettlesome temperature administration specify. As a result, in that respect is an emergence in the force out produced and at the same time it reduces additional equal and the generating appeal.There ar many separate benefits of a have turn military unit plants. Benefits desire high efficiency and woeful environment daze atomic number 18 the most important. In todays world, discharge levels of all kinds of fires must envision stringent regulations acceptable to the countrys gov ernment. It is therefore important for power producers to invest in plants which have menial emissions level. Risk mitigation and public acceptance argon paramount. Combined cycle plants especially those which use natural turgidness or separate renewable resources ar a good choice for low emissions. Carbon dioxide emissions and other bunglees produced in a unite cycle power plant be much lower than other fossil evoke technologies.Power Generation SystemSimple Power deeds hertzA simple power plant generation cycle utilizes lone(prenominal) a single thermo driving cycle at a time. It converts the energy stored in fossil arouses into shaft work and ultimately into electricity. It uses piddle which is loosely in the liquid state and sometimes even in the vapour state, as the working(a) medium. The energy which is released by the shortening the fuel is use to kindle pee and convert it to locomote which is hencely further use to run a turbine to generate electricity. The goer which founders the turbine is sent to a capacity such that the water can be re utilise. However, the efficiency of a simple cycle is still little and massiver amount of cancel out is emitted at the end of the cycle.The efficiency of a simple power plant is given by(cycle) =W(net)/Q(1)=W(T)-W(P)/Q(1)=Q(1)-Q(2)/Q(1)=1-Q (2)/Q (1)The major components of a simple power plant cycle be as make outs(i). Compressor(ii). Combustor(iii). Power turbine(iv). GeneratorIn a simple power plant as seen, ambient demarcation is filtered and therefore fuddled to a compel of 14 to 30 bar (190 to 420 psig). As the assembly line is two-dimensional its embrace add-ons which in turn ar utilize to burn the fuel producing intent grease-gunes with a temperature frequently high than 1,000 spot Celsius. This indeed expands in a turbine driving the compressor and generator. The expanded alive(p) gases leave the turbine at ambient squash and at a temperature between 450 to 650 level Celsius depending on the turbine efficiency, pressure ratio, and turbine inlet temperature. Such a power plant has 35% efficiency only.Gas CompressorIt is a mechanical thingamajig which is used for increasing the pressure of a gas by decreasing its volume. in general disseminate is used in a power plant for compression, however, group O, due north and other gases argon also compressed. There are three general types of compressors, namely, positive displacement, axial and centrifugal.Positive displacement compressors may be reciprocating plunger type, in which the gas is taken in during the suction stroke of the speculator, and is compressed by decreasing the volume of the gas by moving the piston in the opposite direction.Centrifugal compressors use high vivify impeller to increase the energy of the gas which is then converted into pressure in the diffuser. They are used to compress large volume of gas to moderate pressures.In Axial compressors gas is make to flow pa rallel to the axis of rotary motion of the rotor which in turn contains a number of rows of blades. As the gas passes finished the blades its energy increases which is converted into pressure. This type of compressor is used for jet aircraft engines and gas turbines.CombustorIt is a part of turbine where the burning takes place. In a gas turbine, air enters the offset combustion chamber after the compressor. Here, fuel is mixed with the compressed air and the exhaust is then used to drive the turbine to obtain work.A combustor should fulfill the four basic conditions(i). Supply enough air for love combustion of air.(ii). Secure enough turbulence for thorough mixing of fuel and air.(iii). Maintain a furnace temperature high enough to ignite the in attack fuel air mixture.(iv). Provide a furnace volume large enough to suffer time for combustion to be completed.It is important to determine the right amount of oxygen that should enter the combustor. Amounts of Carbon-di-oxide and oxygen are indicators of excess air. If the amount of oxygen is much in the combustor than the take amount, it will burn fuel more rapidly and the efficiency would reduce.A combustor has three master(prenominal) components, namely, the outer caseful which is the high pressure container, the combustion chamber, and the fuel injection constitution. 14 TurbineA move turbine is a prime mover which continuously converts the energy of high-pressure, high temperature steam clean supplied by a steam generator into shaft work with the low temperature steam exhausted to a condenser. This energy conversion essentially occurs in two steps(i). The high pressure, high temperature steam first expands in nozzles and comes out at high velocity.(ii). The high velocity jets of steam coming out of the nozzles, impinge on the blades mounted on a wheel, impersonate deflected by an angle and suffer a loss of momentum which is absorb by the rotating wheel in producing torque.A steam turbine is b asically an group of nozzles and blades. The fig of a Turbine is given down the stairs.Many types of turbines are used in Power localizes, namely1. steamer turbines are used for electricity generation in thermic power plants, i.e. plants employ coal and fuel.2. Gas turbines are also called turbine engines.Every turbine is provided with an emergency control lever which can today shut down the running of turbines in case a catastrophy occurs. all(prenominal) power plant has a fixed turbine rotation rate. These rates at which the turbines rotate are incompatible for different serve. In a power plant the turbines fail to operate if1. Shaft speed exceeds 3300 rpm2. The lubrication dodging fails3. Turbine balancing is non proper4. Temperature of plant increases5. Cooling mechanisms not working properlyControl And Supervisory InstrumentsMany control and supervisory instruments are provided for the safe and effective play of a turbine. They are as follows1. air pressure gauges are used to monitor the pressure of primary(prenominal)(prenominal) steam at dissimilar valves.2. Thermometers are used to record temperatures at every valve and in the combustor valve.3. A Speed recorder is used to monitor the turbine rpm all the time and in case its speed increases beyond a confine value then it is deactivated.4. Watt meters and voltmeters are used to determine the steam and heat rates at various headlands in the procedure.5. A faux pas control lever is provided in case of an emergency.GeneratorIt is a device that converts mechanical energy into electrical energy. A steam generator generates steam at the desired pressure and temperature by burning fuel in its furnace. A generator forces electric charges to be in motion through and through with(predicate) an exterior electrical circuit, but it does not create electricity or charge, which is already present in the wire of its windings.As it can be seen from Fig 4, heat is produced in a generator because of l osses caused by current flow in the stator and field windings. This affects the temperature in the generator. By using cooling mechanisms such an event can be avoided. Generators are usually cooled using hydrogen at very high pressures conjecture at 3 bars. Hydrogen is used since its specific heat is the highest and its molecular weight is the to the lowest degree.Combined cps Power GenerationThe Carnot efficiency is the efficiency of an ideal thermal process. Generally the efficiencies of some processes are less since there are a large amount of losses involved. Thus, a tuberosity between energetic and exergetic losses is drawn. Energetic losses are mainly losses incurred due to heat, and are thus the energy lost in the process. Exergetic losses are internal losses caused by irtwo-sided processes in accordance with the second law of thermodynamics.The process efficiency can be improved by raising the maximum temperature in the cycle, releasing the macerate water at a lower temperature or by modify the process to minimize the internal exergetic losses.The interest in combined cycles arises specially from these considerations. Although, no single cycle can make all the improvements. It thus seems reasonable to combine two cycles to one.Supplementary firing may plague the exhaust temperature to around 900 degree Celsius. to a fault, high gas temperature raises the condition of steam which in turn improves the efficiency of a power plant.The two thermodynamic cycles generally used in a combined cycle power generation are Brayton cycle and Rankine cycle.Brayton CycleIn Brayton cycle the air is first compressed and then at constant pressure reversibly heat is added to it. Due to this, expansion of air takes place in the turbine. This leads to emission of hot gases at a constant pressure which helps in carry it to the sign state. The Brayton cycle consists of 4 cycles in totality, out of which two are reversibly isentropic and the other two are revers ible adiabatic. withal a Brayton cycle is called as the air standard cycle for the gas turbine power plant. 1Cycle ProcessesA. 1-2 isentropic Compression (q = 0)B. 2-3 Isobaric Heat Addition (w = 0)C. 3-4 Isentropic Expansion (q = 0)D. 4-1 Isobaric Heat Rejection (w = 0)Rankine CycleWe can use a theoretic value for every process in the vapor power cycle which represents its basic intended operation and something which does not produce any rectangular effect. From the steam boiler, it is used as a constant pressure high temperature process to convert water to form steam, for the turbine as an ideal reversible adiabatic expansion of steam, for the condenser it is a reversible constant pressure heat rejection as the steam condenses till it becomes pure liquid, and for the bosom, the ideal process is the reversible adiabatic compression of this liquid ending at the initial pressure.When all these four processes are ideal, the cycle is called a Rankine cycle.There are four basic st eps in a Rankine cycleStep1-2 working fluid is pumped to high pressure from its initially low pressure state. This process requires low energy.Step2-3 the high pressure working fluid then enters a boiler where it is heated continuously such that it becomes dry stark(a) vapour.Step 3-4 the dry saturated vapour is then used to turn the blades of a turbine to generate power. The temperature and pressure of the working fluid decreases.Step 4-1 the compressed vapour then enters a condenser where it is condensed to become a saturated liquid.District estrusA district thawing schema uses hot water to bring heat to towns and communities rather than using electrical power. This applied science is quite old. The oldest district hotness system which is still in operation was used to warm a French village from geothermal hot springs in the fourteenth century. Later on, US were the first country to use the process of district heating in plants. A steam district heating system has been in u se by the US oceanic Academy since 1852. The first commercial system began in Denver in as early as 1880. As of today, nearly 30,000 district heating plants are working in the US and there are a thousand more around the world.A district heating plant contains insulated pipes which carry hot water from the plant to various sites. Also these pipes are interconnected between various buildings through a junction point as can be seen from Fig 7. From these junction points, hot water is taken from the mains to a heat ex throwr which is also called a heat sub-station and present inside(a) each building. Because of this the heating circuit which is present inside each building can be isolated from the main heating system. A temperature sensor is present on the heat substation which monitors the temperature of water at all times. Also a meter is attach, which calculates the amount of water consumed by each apartment or building and are charged accordingly. To curb safe and smooth running of the plant, human intervention is reduced by running the plant self-loadingally.Advantages Of Combined Cycle Power generationThe cosmopolitan demand for combined cycle power plants is growing dramatically because of its large advantages, namely(i). High overall plant efficiency up to 70% can be obtained.(ii). menial investment costs up to 30% lower than that required for a conventional steam power plant.(iii). niggling amount of water required amount of cooling water required is only about 40 to 50% as much as for a steam plant.(iv). Great operating flexibility the simple steam cycle makes it achievable to start up and shut down the plants pronto which also affects the efficiency.(v). Phased installation because the gas turbines can go into operation much sooner than the steam plant, installation in stages is possible. The gas turbine can keep on generating power as the steam plant is under construction. This makes it possible to adjust the growth in demand for energy in a grid.(vi). Simplicity of operation combined power plants are fully automatic and are suitable for operating where the operating staff is less experienced.(vii). Low environmental impact because of their low emission levels and high efficiency, such plants are suitable for use in a heavily populated region. 15Components Of A Combined Cycle Power PlantThe major components of a combined cycle power plant are listed belowi. Fuel various types of fuel may be used, namely, natural gas, coal, oil, petrol, diesel or any other conventional source of energy. Generally, natural gas is used as primary fuel. Also, experiments are being conducted to use renewable sources of energy ilk solar energy, wind energy, geothermal energy, nuclear energy and so forthas the main source of fuel. Using renewable source if energy would decrease the cost of running the plant tremendously and increase the efficiency as well. 2ii. HRSG (Heat convalescence Steam Generator) HRSG is a heat exchanger. It is the li nk between the gas turbine and the steam turbine process. It is used to recover heat from a hot gas stream. It produces steam that can be used in a process. HRSG are usually used in a combined-cycle power station, in which the exhaust is ply to the HRSG to generate steam which in-turn drives a steam turbine.There are three main types of HRSGs, namely1. HRSG without secondary firing.2. HRSG with supplementary firing.3. Steam generators with maximum supplementary firing.HRSG without supplementary firing are the most common. Its main function is to convert the exhaust energy of gas turbine into steam. 2iii. Deaerator the main function of a Deaerator is to remove air and other dissolved gases from the water or steam in gas/steam cycle. This is necessary as the high oxygen content present in the steam/water corrodes the components of a plant along with the pipes. Generally, oxygen content of more than 7 to 10 parts per billion(ppb) is highly insecurityous. Deaeration should be done c ontinually since small leakages of air at air flanges and pump seals in the part of the cycle vacuum cannot be avoided. The solubility of the gases increase at a higher temperature and low pressure. A Deaerator removes these gases by heating the feed water to the saturation temperature. This feed water then passes through a heat exchanger after which it is sprayed from the top. By coming in contact dissolved oxygen and carbon di oxide get released. The Deaerator is usually unploughed in between the feed water system such that the total pressure difference between the boiler and the condenser is shared every bit between the condenser pump and the boiler feed pump. The Deaerator is not used water cooled nuclear power plants as there is a danger of radioactive substance release.There are two types of Deaeratorsa. Tray type Deaeratorb. atomizer type Deaeratoriv. Control System In todays world almost all cycles are automated in order to improve the efficiency and at the same time reduc ing human intervention. Control system is to a power plant what a spirit is for a human body. Supervision, control, acting operations in a safe and reliable environment, continuously checking for leakages and faults is all done by the Control System. For this reason, the control and automation systems of a combined cycle power plant form a relatively catchy system even though the thermal process is fairly simple. to the full electronic control systems are employed in todays modern combined cycle plants.The main features of the control system for a combined cycle power plants are1. Truly distributed architecture2. Complete campaign of functions for process control3. Communication capability due to several bus levels4. compliancy with standard communication protocol5. Openness for third party applications6. on-line(a) curriculummability with easy creation/editing of the programsv. Cooling system An engine that is not cooled will soon reach a temperature which will seriously harm its functioning. If the heat is too intense it can cause the lubricant to burn up, leading to souring of cylinders, burning of pistons and bearings or any of variety of other mechanical troubles. Especially in a power plant where combustion of fuel continuously takes place for power generation, excess heat is like an enemy which needs to remove as soon as it is generated, least it would be dangerous.Two types of cooling systems are used, Air cooling and transparent cooling.vi. Cogeneration It is the simultaneous generation of electricity and utilitarian heat. It is basically a recycle process. In conventional power plants, the waste heat is released into the atmosphere. Cogeneration captures this heat and re uses it for industrial heating purposes. In processes like district heating temperatures up to 130C can be reached. Manhattan is the biggest steam district in the world. Many European countries also make use of this technology.Using cogeneration a bottoming plant captures the byproduct heat for domestic and industrial purposes thus increasing the overall efficiency of a plant.Paper and textile mills, chemical factories, dirty money factories etc are few of the many industries which use saturated steam as the desired temperature for many purposes like heating and drying. For constant heating or drying steam is used. Also, the intentness also needs power to drive its various machines. For this purpose combined cycle plants which use cogeneration are used since it serves two the purposes.District Heating Through CogenerationCogeneration involves the production of both electricity and thermal energy simultaneously from a common fuel source. The rejected or exhaust heat is used here for the process of district heating. early(a) applications included Desalination cooling. District heating is the latest technology for heating of homes and buildings in cold places like Europe. Heat which is produced in the thermal fraction in form of hot water is trans ported to houses and other areas using insulated pipes, such that the temperature doesnt change and a separate boiler is not needed at the receiving end.Vapor Absorption SystemA vapor absorption system can be used in the process of district heating. This system uses Ammonia which has a relative lower boiling point than water. Thus, less heat is needed to heat the water. Later ammonia can be removed from the water-ammonia mixture and reused again.The flow chart for such a system is as followsAdvantages Of District HeatingThere are many advantages of using this technology. A few of them are as follows1. Heat is transported to the urban areas using a heat exchanger which has a longer life.2. Water is the main carrier. It can be easily procured from sea (desalination) or underground water.3. Heating equipment takes less space and can be easily installed.4. It can be used all year along without ant breaks.5. Efficiency is more.6. distribution system is controlled using Computer which au tomatically increases or decreases the amount of water being delivered, depending upon the needs.Operation Of A Combined Cycle Power PlantUsually a combined cycle power plants are operated automatically. There are switches available which make it possible to activate the starting or shutting down of the equipment from a central control room. The commands may be given by operating staff or from a high level starting program which runs automatically. The start and stop are contumacious on several parameters which are pre defined in the program.Because the plants have a shorter start up time and an even quicker load change capability, the combined cycle power plants are often called to be dynamic in its behaviour. It is also quick in reacting, thus it is capable of chase up quick changes. 26Modern CCPP in the 50-400 MW range can be started within the following timesFor a combined cycle power plant, Start up procedure is divided into three stages1. HRSG purging2. rush up and synchron ization of Gas turbine3. Speeding up and synchronization of Steam turbinePurging of the boilers is a very important process. It prevents any explosion from unburned hydrocarbons by running the gas turbine at a high ignition speed of about more than 30% of normal speed, which helps in blowing of air through the HRSG. Purging then depends on the volume of gas left canful in the gas turbine. After the purging has been done, the gas turbines run at nominal speed, synchronized and loaded to the desired level. 7Programmable Logic ControllerPlc translationA programmable Logic Controller, which is generally called as PLC, is a state of the art, digital industrial computer. A programmable logical system controller is an industrial computer in which control devices such as limit switches, push buttons, temperature sensors or pressure sensors provide incoming control signals into the unit. An incoming control signal is called an Input. elect(postnominal) control signals interact with center ings specified in the user be given program, which tells the PLC how to react to the incoming signals. The user program also directs the PLC on how to control the field devices like starter lights. A signal going out of the PLC to control a field device is called an Output. 5Advantages Of PlcThe main advantages of using PLC in the field are as follows(i). Gain complete control of the manufacturing process(ii). Achieve consistency in automation(iii). Improve quality and truth(iv). Work in difficult hazardous condition(v). Shorten time to market(vi). Lower the cost of quality, scrap and rework(vii). Offer great product variety(viii). Control inventory5How Does PLC WorkMicroprocessor is the main working brain of all the computers. The computers microprocessor, which is technically known as the central processing unit (CPU), supervises many controls and instructions as defined by the user. The microprocessor responds to the input signals and follows the instruction that it has been p rogrammed to do. When the PLC is running and is following the programmers instructions it is called as solving the user problem.PLCs follow the instructions that are stored inside their stock. Also they may store programs for futurity use. Each instruction that has been entered will be placed inside the memory in the increasing order. These lists of instructions are called as a tally diagram.A basic PLC and its components are shown below.The instructions that are required to be carried out are transferred to the memory of the controller using a computer. The fall apart diagram is made by the user using various kinds of latches, timers, counters and other accessories available with the software. After the running diagram has been verified and corrected, we download the program into the processors memory. Downloading basically means transferring the program from a personal computers memory to the logic controllers memory.Before downloading a user program, the processor must be i n the program mode. After downloading the entire program all the wires have to be connected properly unless the required outputs would not be shown. Also, one can download the program as many number of times as it may be required. The continual running of the program in the PLC is useful in continuously determining if any input is being changed by the user or not. This process is called scanning. According to the commands given and the kind of timers or counters used, the output would be shown which is basically turning of the output light, which is present on the right hand side of the controller.A PLC interfaced with a computer is shown below.The PLC has come a long way since the first time it was used for industry applications. In these years, the PLCs usage has been increased drastically. It has been designed to withstand the harsh temperature. Since mostly PLCs are employed in industries where the temperature is usually on a higher side, they have been made resistant to heat. I t is for this reason it is called as industrially treated device. Also PLCs are small and easy to store. Also they require marginal of space. Also PLC gives the user the ability to try new things.The PLC can easily be programmed for any number of times. The programs are developed from the ladder diagrams. As an industrial computer, the PLC can easily replace functions of timers or counters. Also any type of sequence can be tried on the software. Also these days functions like arithmetic and data manipulation or time out registers have been made available along with the software which has increased its range of operation.The main benefit of using PLC is easy troubleshooting. In industries ladder diagrams may span for many pages. As a result it becomes very difficult to identify the errors. However, PLC software comes with an inbuilt troubleshooting device which tells the user where errors have occurred, if any. This helps in easy identifying of the problem and saves precious time. PLC, thus, is a very important beak in industry usage. RS LOGIX 500RSLogix is a used to run a particular or a full segment in an industry. RSLogix is a product of Allen-Bradley, which provide the best industry controllers. This software offers unbeatable productiveness and is widely used in industries. A simpler version called RSLogix 500 was made by Allen-Bradley for laboratory purposes. I have used this software for interfacing different cycles in a combined cycle power plant. RSLogix 500 offers 5(i). compromising easy to use editors(ii). Diagnostics(iii). Troubleshooting tools(iv). Time saving features and functionalitySimulation On Rs Logix 500The dispatch was divided into three parts1. Brayton Cycle2. Rankine Cycle3. District HeatingLadder diagrams for each were constructed after thoroughly rationality each process in detail. Use of timers, counters and switches were made in the ladder diagrams to illustrate limit switches. Temperature and pressure values have been fictive and are not based on actual standards.RSLogix 500 provides with a large variety of instruction palettes, like normally open closed switches, timers, counters etc. Values of temperature and pressure sensors were assumed and are not based on factual data. Also, various kinds of up-counters and down-counters along with many types of timers were used in innovation of the ladder diagrams. I started with designing of ladder diagram for Brayton cycle. Then I designed a Rankine cycle which uses the waste of Brayton cycle as the input and lastly I designed a District Heating plant which uses the wasteful outputs of both Brayton and Rankine cycles. A Combined Cycle Power Plant increases the efficiency of a power plant by almost double. As a result, its usage is increasing globally as more and more simple plants are being converted to combined cycle power plants.Given below is the figure of an instruction palette as seen in the software.After the Ladder logic is entered, the whole file or p roject is verified without errors and is given access for download.The figure for the same is given belowBrayton CycleThe ladder diagram is as shown below. It has a lower efficiency than a steam cycle.The above figure shows the ladder diagram for the Brayton Cycle. The first rung illustrates the fuel which is supplied. I have taken Natural gas as the main source of fuel and Diesel for emergencies. The fuel mixes with Air. The ratio of fuel air is about 130. A timer which acts like a pressure sensor is attached in parallel with the compressor. Since this timer is attached to a done bit, it cuts off the fuel and air supply after 15 seconds. This is so done since it is assumed that after, say 15 seconds, the pressure in the compressor reaches 200 Bar. If the compressor is opened for more time, then the compressor efficiency blow off because of extreme pressure. This pressure I have assumed is totally hypothetical and varies with the type of material used in the do of the compressor. After the air and fuel gets compressed i.e. the pressure increases and the volume decreases (according to Boyles law), then the compressor valve opens. The compressor mixture then enters a combustor where the combustion takes place. I have attached a up-counter in parallel with the combustor. The up-counter does the same function