STUDY AND PERFORMANCE ANALYSIS OF 210 MW LMW TURBINE A PROJECT REPORT Submitted by PRABHU.K.M PRASATH.P SELVARAJ.R SRIDHARAN.S

In partial fulfillment for the award of the degree Of BACHELOR OF ENGINEERING in

DEPARTMENT OF MECHANICAL ENGINEERING PAVAI COLLEGE OF TECHNOLOGY, NAMAKKAL-637 018 ANNA UNIVERSITY: CHNENNAI 600 025 APRIL-2014

BONAFIDE CERTIFICATE Certified that this project report STUDY AND PERFORMANCE ANALYSIS OF 210 MW LMW TURBINE is the bonafide work of PRABHU.K.M, PRASATH.P, SELVARAJ.R, SRIDHARAN.S who carried out the project work under my supervision.

SIGNATURE SIGNATUREMr.S.DINAKARAN, M.E.,(Ph,D) Mr.C.PRABHU,M.E.,(Ph.D)Professor, Asst.Professor,HEAD OF THE DEPARTMENT SUPERVISORMECHANICAL DEPARTMENT MECHANICAL DEPARTMENTPavai college of technology, Pavai college of technology,Namakkal -637 018. Namakkal-637 018.

Submitted for the viva voce examination held on.......................... INTERNAL EXAMINER EXTERNAL EXAMINER

ACKNOWLEDGEMENT

At the outset we wish to express our sincere gratitude and indebted need to our esteemed institution of Pavai College of technology, pachal which has given this opportunity to have sincere bases in management and fulfilment our most cherish of reaming goal of becoming successful leader. We wish to express our sincere thanks to chairman shri.CA.N.V.Natarajan,B.com,F.C.A., correspondent smt.Mangainatarajan, M.sc., for providing us the needed facilities to do our project work. We express our thanks to our Director Administrative Dr.K.K.Ramasamy,ME., (Ph.D). For his motivation to carrying out our project work. We express our thanks to our Principal Dr.J.Sunderarajan, M.Tech., Ph.D., for this encouragement given to us in carrying on the project work. We express our sincere gratitude to the head of mechanical engineering department prof.S.Dinakaran, ME.,(Ph.D). for his timely support and encouragement throughout the project completion. We express our sincere gratitude to the supervisor of our project C.Prabhu,M.E(PhD)., of the mechanical engineering, who lead a helping hand power, whenever we are in need of it and who gave us valuable suggestions, advice , motivation and encouragement We express our guide to friends who have helped us directly or indirectly for the successful completion the project work.Last but not least we express our deep gratitude to our parents for the their encouragement and support throughout the project work.

ABSTRACT

Steam turbine is an excellent prime mover to convert heat energy of steam to mechanical energy. Of all heat engines and prime movers the steam turbine is nearest to the ideal and it is widely used in power plants and in all industries where power is needed for process. In power generation mostly steam turbine is used because of its greater thermal efficiency and higher power-to-weight ratio. Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator about 63% of all electricity generation in the world is by use of steam turbines. The project deals with the study and performance analysis of typical 210 MW LMW turbine, which is one of the deciding factor used for analysis of power and efficiency and giving the suggestion .

CHAPTER 1 INTRODUCTION In power generation mostly steam turbine is used because of its greater thermal efficiency and high power to weight ratio. Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator about 63% of all electricity generation in the world is by use of steam turbines. Steam turbine has an ability to utilize high pressure and high temperature steam. The power generation in a steam turbine is at a uniform rate, therefore necessity to use flywheel is not felt. Much higher speeds and greater range of speed is possible for a a steam turbine. No internal lubrication is required as there are no rubbing parts in the steam turbine. It can utilise high vacuum very advantageously. Due to the above said salient features, of all heat engines and prime movers the steam turbine is nearest to the ideal and is widely used in power generation.

The steam turbine is essentially a flow machine in which heat energy in the steam is transferred into kinetic energy and its kinetic energy is utilised to rotate the rotor while steam flows through the turbine. During the flow of steam through the nozzle, the heat energy is converted into kinetic energy. The steam with high velocity enters the turbine blades and suffers a change in direction of motion which gives rise to change of momentum and therefore to a force. This constitutes the driving force of the turbine. This force acting on the blades in the circumferential direction sets up the rotation of the wheels or rotor. As the wheel rotates each one of the blades fixed on the rim of the wheel comes into action of the jet of steam which causes the wheel to rotate continuously.

CHAPTER 2

TURBINE DESCRIPTION

2.1 GENERAL DESCRIPTION OF A 210 MW (LMW) STEAMTURBINE Before discussing in details about various features of the steam turbine and its auxiliaries let us have an over view of the system as a whole. (Fig.2.1) shows the schematic of a 21OMW steam turbine (BHEL/LMW).Superheated steam (130KglcM2,535'c) from the boiler enters in to the Highpressure turbine through two emergency stop valves (ESVs) and four control valves (CVs). The high pressure turbine (HPT) comprises of 12 stages, the first stage being governing stage. The steam flow in High pressure turbine (HPT) being in reverse direction, the blades in high pressure turbine HPT are designed for anticlockwise rotation, when viewed in the direction of steam flow. After passing through High pressure turbine (HP]) steam (27 Kg/cm 327'C) flows to boiler for reheating and reheated steam (24.5 Kglcm2, 535oC) comes to the intermediate pressure turbine (IP'T) through two interceptor valves (IVs) and four control valves (CVs) mounted on the IPT it self.The intermediate pressure turbine has 1 1 stages. High pressure turbine (HPT) and intermediate pressure turbine (I PT) rotors are connected by rigid coupling and have a common bearing. After flowing through intermediate pressure turbine (IPT), steam enters the middle part of low pressure turbine (LPT) through two crossover pipes. In low pressure turbine, steam flows in the opposite paths having four stages in each path. After leaving the low pressure turbine the exhaust steam (0.09 KgIcm2 abs) condenses in the condensers welded directly to the exhaust part of the low pressure turbine. Rotors of intermediate and low pressure turbines are connected by a semi flexible coupling.

The direction of rotation of the rotors is clock wise when viewed from the front bearing end towards the generator. The three rotors are supported in five bearings. The common bearing of High pressure and Intermediate pressure rotors is a combined journal and radial thrust bearing. Turbine is equipped with a turning (barring) gear which rotates the rotor of the turbine at a speed of nearly 3.4 rpm for providing uniform heating during starting and uniform coiling during shut down. Seven steam extractions for feed water heating have been taken from gth, 12th, 1 Sth, 18th, 21 st, 23rd & 25th stage. Condensate from the hot well of condenser is pumped by the condensatepumps, and supplied to the deaerator through ejectors, gland steam cooler and four number low pressure heaters. Steam is extracted from the various points of the turbine to heat the condensate in these heat exchangers. From deaeratc)r the feed water is supplied to boiler by boiler feed pumps through three number High pressure heaters.

TURBINEWhat is Turbine? Turbine is the prime mover for the Generator It is a rotating machine. Receives energy in the form of Heat. Thermal energy is converted into rotational energy by means of blades of Impulse and Reaction. This rotational energy is used in Generator to generate power

TYPES AND WORKING PRINCIPLES STEAM TURBINES INTRODUCTION Steam turbine is a rotating machine which- CONVERTS HEAT ENERGY OFSTEAM TOMECHANICAL ENERGY. In India, steam turbines of different capacities, varying from 15 MW to 500MW, are employed in the field of thermal power generation. The design, material, auxiliary systems etc. vary widely from each other depending on the capacity and manufacturer of the sets. Therefore the discussions in the chapters will follow the general patterns applicable to almost all types of turbines, with reference to the specific features of 21 0 MW steam turbines (both L.M.W. Soviet & KWU German Designs)'and 500 MW (KWU) turbines which form the backbone of the thermal power sector in India.

DEVELOPMENT OF STEAMTURBINE Historically, first steam turbine was produced by Hero, a Greek Philosopher, in 120B.C. (Fig. 1. l.). As the fig. shows, k was a pure reaction turbine (explained at 1.4).In 1629, an Malian. Named Branch actually anticipated the boiler-steam turbine combination that is a major source of power today. The concept, is illustrated in (Fig. 1.2). First practical steam turbine was introduced by Charles Parsons in 1884 which was also of the reaction type. Just after five years, in 1889, Gustav De Lava] produced the first practical impulse turbine.

Active development of steam turbine made ft the principal prime mover of generating stations by 1920. Most units used 14 kg/cm2 and 276oc steam and capacity ranged from 5,000 'La 30,000 KW. By 1930 steam M2 conditions rose to 48 kg/c and 398oc and by 1940 steam condition of 81 kg/cm' and 509oc was achieved. After second world war (1 945), reheat. cycle was adopted widely and capacity increased gradually. While turbines of 900 MW are in use in USSR, in India the largest capacity is 50&MW with steam condition of 179

WORKING PRINCIPLES When steam is allowed to expand through a narrow orifice, ft assumes kinetic energy at the expense of its enthalpy (heat emrgy). This kinetic energy of steam is changed to mechanical (rotational) energy through the impact (impulse) 6r reaction of steam against the blades. It should be realized that the blade of the turbine obtains no motive force from the static pressure of the steam or from any impact of the steam jet. The blades are designed in such a way, that steam will glide on and off the blade without any tendency to strike it.As the steam moves over the blades, its direction is continuously changingand centrifugal pressure exerted as the result is normal to the blade surface at allpoints. The total motive force acting on the blade is thus the resultant of all thecentrifugal forces plus the change of momentum. (Fig. 1.3). This causes therotational motion of the blades.PDF created

FIG. 1.4 SIMPLE IMPULSE TURBINE TURBINE TYPES Basically there are two broad classifications of steam turbines:

i) Impulse: In Impulse turbine(Fig.1.4),the steam is expanded (i.e. pressure isreduced) in fixed nozzles. The high-velocity steam issuing from the nozzles does work on the moving blades which causes the shaft to rotate, The essential feature of an impulse turbine is that all the pressure drops occur in the nozzles only, and there is no pressure drop over the moving blades.

ii) Impulse-reaction : In this type, pressure is reduced in both fixed and movingblades. Both fixed and moving blades act like nozzles and are of same shape. Work is done by the impulse affect due to the reversal of direction of the high velocity steam plus a reaction effect due to the expansion of steam through the moving blades. This turbine is commonly called a reaction turbine and is shown below in (Fig.1.5).1.4 COMPOUNDING Several problems crop up if the energy of steam is converted in one step, i.e. in a single row of nozzle-blade combination. With all heat drop taking place in one row of nozzles (or single row of nozzles and blades in case of reaction turbine) the steam velocity becomes very high and even supersonic (velocity of steam is proportional to square root of heat drop in nozzle; V=44.8/K(H1-H2) m/s. K=constant, H, Enthalpy at nozzle inlet ; H 2 Enthalpy at nozzle outlet. The rotational speed of the turbine also becomes very high and impracticable. So, in order to convert the energy of steam within practical speed range, it is necessary to convert R in several steps and thus reducing the velocity of steam and rotor speed to practical levels. This is termed compounding.Following are the various types of compounding.

Velocity Compounded Impulse Turbine (Fig. 1.6) Like simple impulse turbine this has also only one set of nozzles and entire steam pressure drop takes place there. The kinetic energy of high velocity steam issuing from nozzles is utilised in a number of moving row of blades with fixed blades in between them (instead of a single row of moving blades in simple impulse turbine). PDF created

MULTI STAGE TURBINES Two are more turbine using that is called multi stage turbine .following turbine used for this system High pressure turbine Inter mediate turbine Low pressure turbineHIGH PRESSURE TURBINE

Impulse Reaction Turbine No of stages :12(1+11) Shaft out put:65MW Inlet/outlet Steam flow :630/590 t/hr Inlet/outlet Steam temp : 535/330 deg Inlet/outlet Steam pr. : 130/26 ksc INTERMEDIATE PRESSURE TURBINE Reaction Turbine No of stages :11 Shaft out put:105MW Inlet/outlet Steam flow :540/461 t/hr Inlet/outlet Steam temp : 535/190 deg Inlet/outlet Steam pr. : 24/1.32 ksc

LOW PRESSURE TURBINE

No of stages :8(4+4) Shaft out put:40MW Inlet/outlet Steam flow :461/446 t/hr Inlet/outlet Steam temp : 190/45 deg Inlet/outlet Steam pr. : 1.32/0.06 ksc

RANKINE CYCLE The Rankine cycle is a model that is used to predict the performance of steam turbine systems. The Rankine cycle is an idealized thermodynamic cycle of a heat engine that converts heat into mechanical work. The heat is supplied externally to a closed loop, which usually uses water as the working fluid. It is named after William John Macquorn Rankine, a Scottish polymath and Glasgow University professor.

Physical layout of the four main devices used in the Rankine cycle The Rankine cycle closely describes the process by which steam-operated heat engines commonly found in thermal power generation plants generate power. The heat sources used in these power plants are usually nuclear fission or the combustion of fossil fuels such as coal, natural gas, and oil. The efficiency of the Rankine cycle is limited by the high heat of vaporization of the working fluid. Also, unless the pressure and temperature reach super critical levels in the steam boiler, the temperature range the cycle can operate over is quite small: steam turbine entry temperatures are typically around 565C and steam condenser temperatures are around 30C. This gives a theoretical maximum Carnot efficiency for the steam turbine alone of about 63% compared with an actual overall thermal efficiency of up to 42% for a modern coal-fired power station. This low steam turbine entry temperature (compared to a gas turbine) is why the Rankine (steam) cycle is often used as a bottoming cycle to recover otherwise rejected heat in combined-cycle gas turbine power stations. The working fluid in a Rankine cycle follows a closed loop and is reused constantly. The water vapor with condensed droplets often seen billowing from power stations is created by the cooling systems (not directly from the closed-loop Rankine power cycle) and represents the means for (low temperature) waste heat to exit the system, allowing for the addition of (higher temperature) heat that can then be converted to useful work (power). This 'exhaust' heat is represented by the "Qout" flowing out of the lower side of the cycle shown in the T/s diagram below. Cooling towers operate as large heat exchangers by absorbing the latent heat of vaporization of the working fluid and simultaneously evaporating cooling water to the atmosphere. While many substances could be used as the working fluid in the Rankine cycle, water is usually the fluid of choice due to its favorable properties, such as its non-toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties. By condensing the working steam vapor to a liquid the pressure at the turbine outlet is lowered and the energy required by the feed pump consumes only 1% to 3% of the turbine output power and these factors contribute to a higher efficiency for the cycle. The benefit of this is offset by the low temperatures of steam admitted to the turbine(s). Gas turbines, for instance, have turbine entry temperatures approaching 1500C. However, the thermal efficiencies of actual large steam power stations and large modern gas turbine stations are similar.

The four processes in the Rankine cycle

Ts diagram of a typical Rankine cycle operating between pressures of 0.06bar and 50bar There are four processes in the Rankine cycle. These states are identified by numbers (in brown) in the above Ts diagram. Process 1-2: The working fluid is pumped from low to high pressure. As the fluid is a liquid at this stage, the pump requires little input energy. Process 2-3: The high pressure liquid enters a boiler where it is heated at constant pressure by an external heat source to become a dry saturated vapour. The input energy required can be easily calculated using mollier diagram or h-s chart or enthalpy-entropy chart also known as steam tables. Process 3-4: The dry saturated vapour expands through a turbine, generating power. This decreases the temperature and pressure of the vapour, and some condensation may occur. The output in this process can be easily calculated using the Enthalpy-entropy chart or the steam tables. Process 4-1: The wet vapour then enters a condenser where it is condensed at a constant pressure to become a saturated liquid. In an ideal Rankine cycle the pump and turbine would be isentropic, i.e., the pump and turbine would generate no entropy and hence maximize the net work output. Processes 1-2 and 3-4 would be represented by vertical lines on the T-S diagram and more closely resemble that of the Carnot cycle. The Rankine cycle shown here prevents the vapor ending up in the superheat region after the expansion in the turbine, [1] which reduces the energy removed by the condensers.

TURBINE SYSTEMS1. STEAM SYSTEM 2. TURBINE DRAIN SYSTEM3. FEED WATER SYSTEM4. CONDENSER VACUUM SYSTEM5. GLAND SEALING SYSTEM6. LUBE OIL SYSTEM7. GOVERING SYSTEM

STEAM SYSTEM The boiler feedwater 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 0.31.0 microsiemens per centimeter. The makeup water in a 500MWe 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. The feed water cycle begins with condensate water being pumped out of the condenser after traveling through the steam turbines. The condensate flow rate at full load in a 500MW plant is about 6,000 US gallons per minute (400 L/s). Diagram of boiler feed water deaerator (with vertical, domed aeration section and horizontal water storage section). The water is pressurized in two stages, and flows through a series of six or seven intermediate feed water heaters, heated up at each point with steam extracted from an appropriate duct on the turbines and gaining temperature at each stage. Typically, in the middle of this series of feedwater heaters, and before the second stage of pressurization, the condensate plus the makeup water flows through a deaerator[8][9] that removes dissolved air from the water, further purifying and reducing its corrosiveness. The water may be dosed following this point with hydrazine, a chemical that removes the remaining oxygen in the water to below 5 parts per billion (ppb).[vague] It is also dosed with pH control agents such as ammonia or morpholine to keep the residual acidity low and thus non-corrosive.Boiler operation The boiler is a rectangular furnace about 50 feet (15m) on a side and 130 feet (40m) tall. Its walls are made of a web of high pressure steel tubes about 2.3 inches (58mm) in diameter. 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 center. The thermal radiation of 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 1,000F (540C) to prepare it for the turbine. Plants designed for lignite (brown coal) are increasingly used in locations as varied as Germany, Victoria, Australia and North Dakota. Lignite is a much younger form of coal than black coal. It has a lower energy density than black coal and requires a much larger furnace for equivalent heat output. Such coals may contain up to 70% water and ash, yielding lower furnace temperatures and requiring larger induced-draft fans. The firing systems also differ from black coal and typically draw hot gas from the furnace-exit level and mix it with the incoming coal in fan-type mills that inject the pulverized coal and hot gas mixture into the boiler. Plants that use gas turbines to heat the water for conversion into steam use boilers known as heat recovery steam generators (HRSG). The exhaust heat from the gas turbines is used to make superheated steam that is then used in a conventional water-steam generation cycle, as described in gas turbine combined-cycle plants section below.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 downcomers 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 downcomers 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 downcomers 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.Steam condensing The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases.

Diagram of a typical water-cooled surface condenser.[6][7][10][11] The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes.[6][10][11][12] The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary motor-driven exhausters for continuous removal of air and gases from the steam side to maintain vacuum.For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 C where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensible air into the closed loop must be prevented. Typically the cooling water causes the steam to condense at a temperature of about 35C (95F) and that creates an absolute pressure in the condenser of about 27kPa (0.592.07inHg), i.e. a vacuum of about 95kPa (28inHg) relative to atmospheric pressure. The large decrease in volume that occurs when water vapor condenses to liquid creates the low vacuum that helps pull steam through and increase the efficiency of the turbines. The limiting factor is the temperature of the cooling water and that, in turn, is limited by the prevailing average climatic conditions at the power plant's location (it may be possible to lower the temperature beyond the turbine limits during winter, causing excessive condensation in the turbine). Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning.STEAM TURBINE GOVERNING SYSTEM Steam turbine governing is the procedure of controlling the flow rate of steam into a steam turbine so as to maintain its speed of rotation as constant. The variation in load during the operation of a steam turbine can have a significant impact on its performance. In a practical situation the load frequently varies from the designed or economic load and thus there always exists a considerable deviation from the desired performance of the turbine.[1] The primary objective in the steam turbine operation is to maintain a constant speed of rotation irrespective of the varying load. This can be achieved by means of governing in a steam turbine.

Overview Steam Turbine Governing is the procedure of monitoring and controlling the flow rate of steam into the turbine with the objective of maintaining its speed of rotation as constant. The flow rate of steam is monitored and controlled by interposing valves between the boiler and the turbine.[2] Depending upon the particular method adopted for control of steam flow rate, different types of governing methods are being practiced. The principal methods used for governing are described below.Throttle governing In throttle governing the pressure of steam is reduced at the turbine entry thereby decreasing the availability of energy. In this method steam is allowed to pass through a restricted passage thereby reducing its pressure across the governing valve.[2] The flow rate is controlled using a partially opened steam control valve. The reduction in pressure leads to a throttling process in which the enthalpy of steam remains constant.[1]

Figure1: 2-D schematic of throttle governorThrottle governing small turbines Low initial cost and simple mechanism makes throttle governing the most apt method for small steam turbines. The mechanism is illustrated in figure 1. The valve is actuated by using a centrifugal governor which consists of flying balls attached to the arm of the sleeve. A geared mechanism connects the turbine shaft to the rotating shaft on which the sleeve reciprocates axially. With a reduction in the load the turbine shaft speed increases and brings about the movement of the flying balls away from the sleeve axis. This result in an axial movement of the sleeve followed by the activation of a lever, which in turn actuates the main stop valve to a partially opened position to control the flow rate.[2]

Throttle governing big turbines In larger steam turbines an oil operated servo mechanism is used in order to enhance the lever sensitivity. The use of a relay system magnifies the small deflections of the lever connected to the governor sleeve.[2] The differential lever is connected at both the ends to the governor sleeve and the throttle valve spindle respectively. The pilot valves spindle is also connected to the same lever at some intermediate position. Both the pilot valves cover one port each in the oil chamber. The outlets of the oil chamber are connected to an oil drain tank through pipes. The decrease in load during operation of the turbine will bring about increase in the shaft speed thereby lifting the governor sleeve. Deflection occurs in the lever and due to this the pilot valve spindle raises up opening the upper port for oil entry and lower port for oil exit. Pressurized oil from the oil tank enters the cylinder and pushes the relay piston downwards. As the relay piston moves the throttle valve spindle attached to it also descends and partially closes the valve. Thus the steam flow rates can be controlled. When the load on the turbine increases the deflections in the lever are such that the lower port is opened for oil entry and upper port for oil exit. The relay piston moves upwards and the throttle valve spindle ascend upwards opening the valve. The variation of the steam consumption rate (kg/h) with the turbine load during throttle governing is linear and is given by the willans line.[1]Nozzle governing In nozzle governing the flow rate of steam is regulated by opening and shutting of sets of nozzles rather than regulating its pressure.[3] In this method groups of two, three or more nozzles form a set and each set is controlled by a separate valve. The actuation of individual valve closes the corresponding set of nozzle thereby controlling the flow rate. In actual turbine, nozzle governing is applied only to the first stage whereas the subsequent stages remain unaffected.[1] Since no regulation to the pressure is applied, the advantage of this method lies in the exploitation of full boiler pressure and temperature. Figure 2 shows the mechanism of nozzle governing applied to steam turbines.[2] As shown in the figure the three sets of nozzles are controlled by means of three separate valves.

Figure2: 2-D schematic of nozzle governorBy pass governing Occasionally the turbine is overloaded for short durations. During such operation, bypass valves are opened and fresh steam is introduced into the later stages of the turbine. This generates more energy to satisfy the increased load. The schematic of bypass governing is as shown in figure3.

Figure3: 2-D schematic of bypass governorCombination governing Combination governing employs usage of any two of the above mentioned methods of governing. Generally bypass and nozzle governing are used simultaneously to match the load on turbine as shown in figure 3.Emergency governing Every steam turbine is also provided with emergency governors which come into action under the following condition.[2] When the speed of shaft increases beyond 110%. Balancing of the turbine is disturbed. Failure of the lubrication system. Vacuum in the condenser is quite less or supply of coolant to the condenser is inadequate.

FEED WATER SYSTEM PURPOSE: (1)TO RECEIVE THE WATER THAT IS STORED IN DEAERATOR FEED WATER TANK. (2)TO PRESSURISE THE WATER SO THAT IT CAN BE SENT TO THE BOILER. (3)AUXILIARY FUNCTIONS OF BFP. *TO SEND WATER TO SH/ RH ATTEMPERATION. * TO SEND WATER TO HP BY PASS ATTEMPERATION.

* TO SEND WATER TO PRDS ATTEMPERATION IN ADDITION TO WATER FROM CEP.

GLANDS AND GLAND SEALING SYSTEMS

GLANDS Glands are used on turbine to prevent or reduce the leakage of steam or air between rotating and stationary components which have a pressure difference across them; this applies particularly where the turbine shaft passes through the cylinder. If the cylinder pressure is higher than atmospheric pressure there will be a general steam leakage outwards; d the cylinder is below atmospheric pressure there Mil be a leakage of air inwards, and some sort of sealing system must be used to prevent the air from entering the cylinder and the condenser.

Water-sealed glands Some turbine designs incorporate a shaft gland which depends on a water seal to prevent steam or air leakage. A typical seal arrangement (Fig. 4.1) consists of a shaft - mounted impeller with a series of vanes or pockets machined on both faces. The impeller is contained within an annular chamber, and, when water is admitted to the chamber, the impeller vanes force the water to rotate, at a speed approximately equal to the impeller speed. The seal is relatively inefficient at low speeds and air-sealed auxiliary labyrinth glands must be used, in conjunction with high capacity air pumps, to raise vacuum when starting. Water is usually injected into the seal at approximately hag of the full operating speed.

TURBINE OIL SYSTEM

purpose of oil system The turbine oil system fulfils four fuctions. It:a) Provides a supply of oil to the journal bearings to give an oil wedge at the shaft rotates.b) Maintains the temperature of the turbine bearings constant at the required level. The oil does this by removing the heat which is produced by the shaftconduction, the surface friction and the turbulence set up in the oil.c) Provides a mediumfor hydraulically operating the governor gear and controlling the steam admission valves.d) Provides for hydrogen-cooled generators a sealing medium to prevent hydrogen leaking out along the shaft. It is worth noting that for 500 MW unites and above, h is becoming the practice to use fire resistant fluids in place of lubricating oil for the control of governer gear and steam admission valves. These eliminate the risk of fire caused by leakage which is particularly likely when higher fluid pressures are used. shows the schematic of the lubricating oil system for 21 0 MW (BHEL/ LMW) turbine. Lubricating oil systems for power station steam turbines of other make or ratings also are a more or less simillar.

OIL SPECIFICATION (210 MWJLMWTurbine 011)1 . Recommended Oil a) Turbine oil 14 b) Mobil DTE medium2. a) Specific gravity at 50'c 0.852 b) Kinematic viscosity at 50'c 28 CS c) Neutralisation number 0.2d) Flash point 201'c (min)e) Pour point -6.60c (max)f) Ash percentage by weight 0.01%g) Mechanical impurities Nil

8.2 SYSTEM The turbine oil system consists of the following: 1.Main oil pump 2. Starting oil pump 3. A.C. Lub oil pump 4.. D.C. emergency oil pump 5. Oil tank 6. Drain valve

Lubricating oil is supplied from oil tank (capacity 28,000 lftres) to bearings and governing system with the help of pumps. During period of normal operation the required oil is supplied through the main oil pump mounted on the turbine shaft. A portion of discharge of the main oil pump is used as the working oil for the injectors. In fact there are two injectors located in the oil tank. The first injector supplies oil to the suction of the main oil pump and the discharged oil is further pressurised through the second injector which supplies oil to the bearings through coolers. During initial starting a A.C. driven starting oil pump meets the requirement of both the bearing oil and governing oil.Two standby oil pumps are incorporated in the system to supply bearing oil in8.2.1 Main Oil Pump This pump is mounted in the front bearing pedestal 'It is coupled with turbine rotor through a gear coupling. When the turbine is running at normal speed i.e. 3000 rpm or the turbine speed is more than 2800 rpm, then the desired quantity of oil to the governing system at 20 Kg 1 cm' (gauge) and to the lubrication system at 1 Kg 1 CM2 (gauge) is supplied by this oil pump. The oil to the lubrication system at the level of turbine axis is supplied through two injectors arranged in series. 8.2.2 Starting Oil Pump (Auxiliary Oil Pump) It is a multi-stage centrifugal oil pump driven by A.C. electric motor. Starting oil pump is provided for meeting the requirement of oil of the turbo set during starting. During starting or when the turbine is running at a speed lower than 2800 rpm ft supplies oil to governing system as well as to the lubrication system.8.2.3 A.C. Lub Oil Pump This is a centrifugal pump, driven by an A.C. electric motor. This runs for about 10 minutes in the beginning to remove air from the governing system and to fill the oil system with the oil. This pump automati over under inter lock action whenever the oil pressure in lubrication system fails to 0.6 kg 1 CM2s (guage). Thus8.2.4 D.C. Emergency Oil Pump This is a centrifugal pump, driven by D.C. electric motor. This pump has been provided as a back-up protection to A. C. driven lub. oil pump. This automatically cuts in whenever there is failure of A.C. supply at power station and or the pressure in the lubrication system fails to 0.5 kg 1 cm, (gauge).8.2.5 Oil Tank The oil is stored in oil tank of 28000 litres capacity upto operating level of the tank. About 4000 lit / min. oil remains in circulation. Liberally sized tank holds the oil inside the tank for a period long enough to ensure liberation of air from the oil. Different mesh sized fitters are located inside the tank to filter the oil during its no~ course. The filters are easily accessible and removable for cleaning even when turbine is in service. This oil tank is supported on the framed structure just below the turbine floor at the left side of the turbine.

TURBINE COMPONENTS

3.1 CASINGS OR CYLINDERS A casing is essentially a pressure vessel which must be capable of withstanding the maximum working pressure and temperature that can be produced within it. The cylinder is supported at each end. The cylinder has to be extremely stiff in a longitudinal direction in order to prevent bending and to allow accurate clearances to be maintained between the fixed and moving parts of the turbine. This determines the length between bearing centres which in turn determines the number of stages which can be accommodated within the cylinder. The working pressure aspects demand thicker and thicker casing and the temperature aspects demand thinner and thinner casings. Design developments took place to take care of both pressure and temperature considerations and resulted in the following three types of casing design.i) Single shell casingii) Multiple(double)shell.easingiii) Barrel type casing

3.1.1 H.P. Turbine Casing a) Single Shell Split Casing : Barlier design turbines including the 21O MW BHEL / L.M.W. varieties are of single shell split casing for H.P. cylinders.In this type the casing thickness would be of the order of about20 cms forthe 21 0 MW turbine which will make the flange to about 40cms and thejointing bolts to about 23 crm size. This ' leads to concentration of masswhere high temperature and sharp fluctuation in temperature h expected.This poses several problems during machine start ups and load changes.b) Double Sheli Casinci: With the rise of steam conditions there fore singleshell casings are of no more use for H igh Pressure (H P) and 1 ntermediatePressure (1 P) casings. By using a double shell casing , the casingthickness has been reduced to 9 cms and bolt size to 1 1 cms. in 21 0 MWturbine H.P. cylinder. (Fig. 3. 1) shows how a double shell reducestemperature difference through metal casing.

3.1.3 L.P. Turbine Casing The LP turbine casing shown in Fig. 2.2 consists of a double-flow unit and has a triple shell welded casing, The outer casing consists of the front and rear walls, the two lateral longitudinal support beams and the upper part. The front and rear walls, as well as the connection areas of the upper part are reinforced by means of circular box beams. The outer casing is supported by the ends of the longitudinal beams on the base plates 3.2 of the foundation.

The double-flow inner casing, which is of double-shell construction,consists of the outer shell and the inner shell. The inner shell is attached in theouter shell with provision forfree thermal movement. Stationary blading is carried bythe innershell. The stationary blade rowsegments of the LP stages are bolted tothe outer shell of the inner casing. The complete inner casing is supported. The design of low pressure cylinders has changed a lot in recent years. Before the advent of the 500 MW machines, condensers were invariably situated beneath the low pressure turbine and the condenser tubes were at right angles to the. axis of the machine. With the development of the 500 MW machines several variations of the above turbine / condenser arrangement have been adopted (Fig. 3.8) shows one such variation with condensers mounted on each side of the I P. casings. These are called pannier condensers.

3.5 STEAM VALVES A turbine is equipped with one or more emergency stop valves, in order to cut off the steam supply dun'rn pe~of shut down and to provide prompt interruption of the steam flow in emergency. In addition govemirl valves are used to provideaccurate control of steam flow entering the turbine. Reheat turbines require addermrgency and interceptor valves . in the return path from the reheater and dualpressure turbines require two of emergency and governing valves. (Fig.3.14)shows some basic schematic designs ol valves in modem use.a) Shows a double--beat" valve having two seatings, the object being to balance the forces due to steam pressure. It is suitable for most pressures, but not for high temperatures as differential expansion between the valve and cage would cause one or other sealing to owrapm.b) Shows another double-beat valve of the hollow type in which the steam from one sealing is led through the centre of the valve. The thinner walls promote even heating and lesser differential expansion.d) Shows a similar valve fitted with an internal pilot valve which, by opening first,equalises the pressures and provides initial fine control.e) Shows a cylindrical valve in which steam pressure is prevented from acting on the back of the valve by fine annular clearance.f) Shows a flap valve, used for reheat emergency valves, where the steam pressures are moderate and the specific volumes (and hence the valve diameters) are large.g) Shows a governing valve of the *mushroom' type, with a profiled skirt to give a more linear area 1 lift relationship. Other types of valves, such as piston and grid valves are used in pass-out turbines. The diameters of valves opening are generally calculated to dive maximum steam veloc~ of about 60 m / sec for. ermrgency valves, and about 120 m 1 sec for governing valves.The seating upon which any such valves closes is invariably part of aremovable sleeve which is replaceable when worn. -rhe mating annular faces ofvalves and their seats are nitrided or faced with Stelide to resist wear. Such wearis due more to erosion by the steam than to mechanical impact and is particularslipme to taker place when the valve is cracked open and a jet of steam is propelled at high velocity through the n arrow port opening by the large pressure differential, impact damage can occur as a result of frequent test ck)sures, and cushioning devices or slow motion testing may be adopted to avoid this.

3.6 LOOP PIPES Steam passes from the steam chest to the turbine via loop pipes which are normally U-shaped to give them sufficient flexibility (ft is important that these loops be provided with drain rocks for use when starting up). With the use of high pressures, the pipe walls have to be thick, making the pipes stiff. To achieve the required flexibility and to avoid the imposition of large forces or bending moments on the turbine very long loops are required. Where pipes enter a double shell cylinder, it is preferable that they enterradially, passing through as liding joint in the outer cylinder; in this way the twosheli scan expand radially without losing concentricity. The sliding joint usuallycontains piston rings made of nimonic alloy or special steel which will retain itsspringiness at the prevailing steam temperature. See (Fig. 3.19 (a).Cross-over pipes between cylinder must also be flexible, as they expand morethan the bearing pedestal and cylinders over which they pass. Pipes with long loops are used for transmitting very hot steam. Where possible, crossover pipes pass under or alongside cylinders rather than overhead, to improve cylinder access. Expansion of LP cross over pipes is taken up by two or more hinge-linkedbellows which allow bending but no axial movement (Fig. 3.19 (b) in this way the pressure force in the pipe is transmitted through the links, thus protecting theconvolutions from the tenency to open out. Afternatively, straight linked bellows may be used in pairs, as shown in

3.6 ROTORS There are two types of turbine rotor used in large turbines which have impulse type a) The built up rotor also called Disc Rotor consisting of a forged steel shaft onwhich separate forged steel discs are shrunk and keyed. (Fig. 3.20).b) The integral rotor in which the wheels and shaft are formed from one solidforging. (Fig. 3.21). The built up rotor is made up of a number of separately forged discs or wheels and the hubs of these wheels are shrunk and keyed on to the central shaft. The outer rims of the wheels have suitable grooves machined to allow for fixing the blades. The shaft is sometimes stepped so that the wheel hubs can be threaded along to their correct positions. Suitable clearances are left between the hubs to allow for expansion axially along the line of the shaft. Integral rotors as said before have discs and shaft machined from one solid forging, the whole rotor being one complete' icce of metal. This results in a rigid construction and troubles due to lobse wheels of the shrunk on type are eliminated. Grooves are machined in the wheel rims to take the necessary blading. These are also called solid forged rotors.

integral rotorThe built-up rotor tends to be the cheaper of the two since the discs and shaft are relatively easy to forge and inspect for flaws; also, the machining of thesecomponents can be carried out concurrently. On the other hand, integral rotors are and difficult to forge and there is a high incidence of rejects; there isalso a large amount of machinery time and waste material involved. In spite of the expenses involved, the advantages of integral rotors are suchthat they are invariably used for the high pressure rotors on high temperatureplant; on reheatmachines in particular they are often used for intermediate pressure and low pressure rotors as well. This is because of the difficulty of ensuring that the shrunk-on discs on intermediate and low pressure rotors cannot become loose, particularly at the high temperature end during start up when the shafts may be relatively cool and the discs are hot. Another source of trouble under conditions of high temperature and stress is the phenomenon of creep which could also cause the shrink-fft to disappear after a large number of running hours. With regard to low pressure rotors, the main problem is one of centrifugal stress, the last stage being the most heavily stressed part of the turbine. The last row wheels on the standard 500 MW turbine are the largest cap able of operating at 1 000 rev 1 min; the blades are 900 mm in length and are mounted on the disc so as to have a mean diameter of 2.5 m, the overall diameter is therefore 3.45 m. On large turbines using 50 per cent reaction, four types of rotor are used:a) The hollow drum rotor which promotes even temperature distribution because it is designed with the same thickness of material as the casing.(Fig. 3.22) illustrates the construction of the hollow drum type rotor.b) The solid drum rotor suitable for cylinders where there are lower temperatures but large diameters, as in intermediate pressure cylinders without reheat.c) The built up rotor previously described.d) Welded Rotors which are built up. From a number of discs and two shaft ends. These are joined together by welding at the circumferences and because, there are no central holes in the discs the whole structure has considerable strength. Small holes are drilled in the discs to allow steam to enter inside the rotor body to give uniform heating when coming on load. Grooves are machined in the discs to carry the blades and (Fig. 3.23) shows this type of rotor construction

3.8 BLADES These are most important components of the turbine . converting heat energy to mechanical energy.A blade has three main parts:- AEROFOIL - It is the working part of the blade- ROOT - It is the portion of the blade which is fixed with therotor or casing.- SHROUD - It can be rivetted to the main blade or can be integrallymachined with the blade(Note: Blades maybe without shroud also)3.8.1 Type of Blades Most modern turbines use reaction type blading throughout the machine.Some designs have impulse in the H.P. and I.P.cylinders and reaction in the L.P.cylinder. But use of impulse or reaction cannot always be dearly defined because both principles may be combined in the same blade. For example large L. P. blades are generally of twisted and tapered design (see fig. 3.24). These blades produce varying conditions of impulse or reaction between root and tip and are called vortex blades. The object of this design is to prevent uneven steam flow caused by centrifugal forces forcing the steam towards blade tips. This is done by changing the throat opening from root to tip. A 915 mrn (36m) blade with zero reaction at the root has approximately 70 per cent reaction at the tip. Also the inlet angle of the blade after along its length giving smooth and efficient steam entry.3.8.2 Impulse Type Moving Blades lmpluse type moving blades (for H.P.. Turbine) are machined from solidbar and the roots and s Tangs are left at the tips of the blades so that when fitted in position in the wheel, shrouding can beattached. The shrouding is made up from sections of metal strip punched with holesto correspond with the tangs. As there is no pressure drop across the movingblade, the seating arrangements are not of such great importance, as in the reaction type. The shrouding on the impluse blading helps to guide the steam through the moving blades, allowing larger radial clearance, as well as strengthening the assembly.

Impulse Type Fixed Blading The fixed blading in an ampluse turbine takes the form of nozzles mounted in diaphragms. The diaphragm is made in two halves, one half being fixed to the upper half of the cylinder casings by means of keys so that when expansion occurs fouling of the shaft seals is avoided. Special carrier rinfs are generally used to support the diaphragms in H.P. cylinders. Because of the steam pressure difference on each side of the diaphragm, seals are provided at the bore where the shaft passes through the diaphragm, to prevent steam leakage along the shaft IMPULSE TYPE FIXED BLADING

In reaction type blading pressure drop occurs across both the fixed andmoving blades. So, very effective seal between fixed and moving blading isessential to prevent steam leakage which would make the turbine inefficient. The leakage of steam controlled by axial clearance is shown in (Fig. 3.27). This type of sealing is called end tightening. Following is the details of Reaction typeblading of the H.P. Turbine of 210 Mw Set (KWU / BHEL).

Moving and Stationary Blades The HP turbine blading consists of several drum strages. All stages are reaction stages with 50 per cent. The stationary and moving blades of the front stages (Fig. 3.28) are provided with T-roots which also determine the distance between the blades. Their cover plates are machined intergral with the blades and provide a continuous shroud after insertion. The moving stationary blades are inserted into appropriately shaped grooves closed casing (1) and are bottom caulked with caulking material (9). The insertion slot in the shaft (8) i a locking blade which is fixed either by taper pins or grub screws. Special end blades which lock with t horizontal joint are used at the horizontal joints of the inner casing. Graub screws which are inserted from t joint into the material secure the stationary blades in the grooves.

3.11 SHAFT TURNING (BARRING) GEAR

Turning gear is provided to rotate turbine shafts slowly during the pre-run up operation and after shut down to prevent uneven heating or cooling of the shafts. The uneven heating or cooling would lead to bending and misalignment of shafts with possible fouling of stationary and moving parts. Use of turning gear during starting eliminates the necessity of admittingsuddenly a large flow of steam to rotate the turbine from the rest.The turning gear speed is chosen to ensure satisfactory lubrication of thebearing and, at the same time, provide some circulation of air within the casing(particularly at the low pressure end) after shut down. The speed of turning gearvaries considerably from one design to another. For example while BHEL 1LMW 210 MW turbine is rotated by the turning gear atthe speed of 3.4 rpm, in500 MW KWU turbines, the T/ G rotates the turbineshaft at 270 R.P.M. / or 240R.P.M. depending on whether the condenser is under vacuum or not.The turbine must remain on turning gear units metal temperature hasdropped below 150"c with normal cooling, this will take approximately 72hours. Before putting the turbine on turning gear a few conditions like-adequatebearing oil pressure, jacking oil pump running etc. must be satisfied.JACKING OIL PUMPS (JOPS) are positive dispi - acement pumps thatprovide high pressure (1 20 bar for KWU turbines) supply of oil under strategicjournals @~turbo generator and the oil lifts the shaft slightly, This ensures thatthere is no metal contact between a journal and the bearing. This greatly reducesthe static friction and bearing wear, also the starting torque headed by the turning gear drive. The JOP can be stopped after the lubricating oil film is established between the shaft and bearings. On early turbo generators, turning of TG was done by hand with the help of long bar fitted with rachet worm and pinion mechanism. (Fig. 3.34). This gave the name "barring gear" or "barring" to this operation. Now, the driving force isprovided by either electric motors or hydraulic pressure.Hand barring gear is used, nowadays, in emergency, when T.G. motor isnon-operational, and for maintenance purposes, to rotate the turbine shaft manually. An auxiliary source of power from U.P.S. (Uninterrupted Power Supply) or Diesel Generating set is also provided in some cases for reliability of T /G operation. Fig.3.35 shows the functional arrangement of a turning gear.In BHEL 1 21 0 MW LMW turbine, the T./ G is mounted on LP rotor rearcoupling. It consists of a worm, worm wheel spur gear and pinion, spiral shaft and sliding shaft with lever. The system comes into operation when the shaft comes to stand still. When T / G isengaged, the turbine shaft rotates at 3.4 R. P.M. In KWU turbines, the turning gear is hydraulic. It is engaged when shaftspeed comes down to 545 R.P.M The T 1 G rotates the shaft at 120 RPM or 80R.P.M. depending on whether the condenser is under vacuum or not. The T / Gassembly is located in the front bearing pedestal of LP cylinder and consists of two rows of moving blades mounted on coupling flange of I.P. rotor, an inlet nozzle box with stationary nozzles and .,guideblades (Fig. 3.36). The TG shaft system is rotated by the double row wheel which is driven by prerssurised oil supplied by auxiliary oil pump. After passing through the blading the oil drains to the bearing pedestal and combines with the bearing lube oil returning to the iube oil tank. In addition, the system is equipped with facility for manual barring in the even of failure of hydraulic turning gear.

3.12 COUPLING3.12.1 IntroductionThe need for couplings arises fromthe limiting length of shaft which it tis possible to forge in one piece and from the frequent need to use different materials for the various rotors, in view of the various conditions of temperature and stress. Couplings are essentially devices fir transmitting torque, but they may also have to allow relative angular misalignment: transmit axial thrust, and ensure axial location or allow relative axial movement. They may be classified as flexible,semi-flexible or rigid. Type of coupling used may vary from manufacturer to manufacturer. Forexample, the BHEL / LMW 210 MW units employs a rigid coupling to connectHP and IP Turbine and a semi flexible one for connecting IP and LP turbine;whereas, both the couplings of 210 MW BHEL /KWU set are of rigid type.Following are the brief descriptions of basic three types of couplings;3.12.2 Flexible CouplingFlexible couplings are capable of absorbing small amounts of angular misalign as well as axial movement. Double flexible couplings can also accommodateeccentricity. Semi-flexible couplings will allow angular bending only.(Fig. 3.37) shows some designs in common use. The claw coupling, whichmay be single or double, is robust and slides easily when transmitting light load; on heavy load, however, friction causes ft to become axially rigid. The Bibby coupling is satisfactory up to medium sizes and provides, in addition to the other features, torsional resilience' The mutti tooth coupling transmits torque by internal and external gear teeth of involute form, which are curved to accommodate angular misalignment, All these couplings require continuous lubrication, normally obtained from a jet of oil feeding into an annual recess, from which k is led centrifugally to the coupling teeth through drilled passage_way

3.12.3 Semi flexible Coupling The semi-flexible type of coupling requires no lubrication and is normally interposed between the turbine and generator. It consists of a hollow piece having one or more convolutions (Fig. 3.38. (a)3.12.4 Rigid Couplings On large turbines the high torque to be transmitted renders the use of flexiblecouplings impracticable. Consequently rigid couplings are employed between the turbine cylinders so that the turbine shaft behaves as one continuous rotor A spigotlocates the two half-couplings and numbered fitted bolts join the flanges

general calculations:date: 23.2.2015unit: 4load: 208 MWtime:11.56 am

READINGSTotal FW flowT/hr-683

Total coal flowT/hr128

Calorific value of coalT/hr

MS pressureKal132/133

MS flow temperature*C539/539

MS flowT/hr650

Enthalpy of main steam819.79

CRH pressureKsc26/27

CRH temperature*C315/315

Enthalpy of CRH steam726.47

HRH pressureKsc24/24

HRH temperature*C536/536

Enthalpy of HRH steam848.32

FW temp at ECO F/L*C234/288

Boiler outlet steam flowT/hr643

AUX. steam flowT/hr14.5

Heat equivalent to 1KWT/hr

IPT exhaust steam pressureksc0.569/0.230

IPT exhaust steam tempKsc185/185

Enthalpy of IPT exhaust *C2843.24

LPT exhaust steam pressureksc-0.996/0.905

LPT exhaust steam tempKsc43/44

Enthalpy of LPT exhaust*C

1)Turbine efficiency Turbine efficiency = (heat output by turbine)/(heat input to turbine) a)heat input to turbine: =(MS flow (MS enthalpy - FW enthalpy)103 ) +(HRH flow (HRH enthalpy - CRH enthalpy) 103) =650 (852.08 - 700) + 554 (849.68 744.37) =157193.74103 kcal.b) heat output by turbine: 1) work done in HPT: = ( MS flow (MS enthalpy HPH 7 ES enthalpy)) + ((MS flow HPH 7 ES flow) [HPH 7 ES enthalpy CRH enthalpy] 103 =650 (852.08 - 755) + [(650 31.05) (755 744.37)] =69681.43103 kcal2) work done in IPT: A) HRH flow (HRH enthalpy HPH 5 enthalpy) =554(849.68 803 ) =25860.72 kcal B ) [HRH flow HRH 5 ES flow ] [HPT 5 enthalpy ] [LPH4 ES enthalpy] =[554 15.26] [803 - 762] =22088.34 kcalC )[HRH flow (HPH5 ES flow + LPH4 ES flow) ] [LPH4 ES enthalpy LPH3 ES enthalpy] =[554 (15.26 + 23.34)] [762 715.8] =24223.8 kcalD ) [HRH flow (HPH5 ES flow + LPH4 ES flow + LPH3 ES flow)] [LPH3 ES enthalpy LPH2 ES enthalpy] =[554 (15.26+23.34+20.34)] [715.8 678.3] =18564.75 kcalAdd equation A, B, C, D. A+B+C+D=25860.72+22088.34+24223.8+18564.75 =90737.61 kcal3) work done in LPT: [LPT steam flow (LPT steam enthalpy LPH 1 enthalpy)] +[ (LPT steam flow LPT 1 flow) (LPH 1 ES enthalpy LPT exhaust enthalpy)]=[46 1.61 (678.5 622.17)] +[(461.61- 16.56 ) (622.17 581.22)] =26002.49 kcalOutput of turbine =HPT+IPT+LPT =69681.43103 + 90737.67 + 26002.49 =186421.53103 KcalEfficiency =( 186421.53103 450993.74103 ) 100 =41.33%Work done in regenerative system =FW flow (enthalpy ECO in/out enthalpy of hot well water) 103 =680 (248 - 45) 103 =138040 103 kcal overall efficiency = (186421.53103 +138040103) (450993.74103) = 71.9%turbine heat rate =( MW generated ) (turbine input 0.9) =860210 103 (4509930.9) =0.44 =44%Turbine efficiency =860turbine heat rate = 860 1932830.314 =4.44