STEAM TURBINE

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A comprehensive presentation on Steam Turbine

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STEAM TURBINE:

STEAM TURBINE Prepared by: Mohammad Shoeb Siddiqui Senior Shift Supervisor Saba Power Company Cell # +92 321 4598293

Introduction:

Introduction What is Steam Turbine? A  Steam Turbine  is a device that extracts  Thermal Energy   from pressurized Steam and uses it to do  Mechanical Energy on a rotating output shaft.  Steam Turbine is device where Kinetic Energy (Heat) converted into Mechanical Energy (in shape of rotation). Turbine is an Engine that converts Energy of Fluid into Mechanical energy & The steam turbine is steam driven rotary engine. This Presentation is base on basic of Steam Turbine & 134 MW Toshiba Steam Turbine. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

SABA POWER PLANT STEAM TURBINE:

SABA POWER PLANT STEAM TURBINE Rating & Design Data Turbine Type: SCSF-36, single cylinder, single flow Reheat condensing turbine. Rated output: 134 MW Speed: 3000 RPM Direction of Revolution: Counter-clock-wise (seeing from turbine front End) Steam Condition: Main Steam Press. (before MSV): 16548 kpa (g) Main Steam Temp. (before MSV): 538 o C Reheat steam Temp. (before CRV): 538 o C Exhaust pressure: 6.77 kpa (g) Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

SABA POWER PLANT STEAM TURBINE:

SABA POWER PLANT STEAM TURBINE Rating & Design Data Number of Extraction: 6 Number of Stage: 21 HP Turbine: 9 stages IP Turbine: 7 stages LP Turbine: 5 stages Number of Wheel: 21 Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Toshiba Steam Turbine Overview:

Toshiba Steam Turbine Overview Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Over View:

Steam Turbine Over View Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor LP Turbine Casing IPTurbine Casing HP Turbine Casing

STEAM TURBINE:

STEAM TURBINE Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines In order to better understand turbine operation, Four Basic Classifications are discussed. Type of Steam Flow & Division of Steam Flow, describes the flow of steam in relation to the axis of the rotor.   indicates whether the steam flows in just one direction or if it flows in more than one direction . Way of Energy Conversion & Type of Blading, Reaction, Impulse and Impulse & Reaction Combine.   identifies the blading as either impulse blading or reaction blading. Type of Compounding & Cylinder arrangement   refers to the use of blading which causes a series of pressure drops, a series of velocity drops, or a combination of the two. (number of cylinders; whether single, tandem or cross-compound in design) Exhausting Condition & Number of Stages   is determined by whether the turbine exhausts into its own condenser or whether it exhausts into another piping system.  Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam T urbines 1. Type of Steam Flow   Turbines may be classified according to the direction of steam flow in relation to the turbine wheel or drum - Axial. Radial. Mixed Tangential Or Helical. Reentry Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines Radial Flow: A turbine may also be constructed so that the steam flow is in a radial direction, either toward or away from the axis. In figure illustrates an impulse, radial flow, auxiliary turbine such as may be used as a pump drive. The radial turbine is not normally the preferred choice for electricity generation and is usually only employed for small output applications Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines Axial Flow: The great majority of turbines, especially those of high power, are axial flow. In such turbines the steam flows in a direction or directions parallel to the axis of the wheel or rotor. The axial flow type of turbine is the most preferred for electricity generation as several cylinders can be easily coupled together to achieve a turbine with a greater output. . Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines Reverse Flow In some modern turbine designs the steam flows through part of the high pressure (HP) cylinder and then is reversed to flow in the opposite direction through the remainder of the HP cylinder. The benefits of this arrangement are: outer casing joint flanges and bolts experience much lower steam conditions than with the one direction design reduction or elimination of axial (parallel to shaft) thrust created within the cylinder lower steam pressure that the outer casing shaft glands have to accommodate A simplified diagram of a reverse flow high pressure cylinder is shown in Figure Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines 2. Way of Energy Conversion & Types of Blading - Impulse turbines Reaction turbines Impulse & Reaction Combine Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines By Types of Blading : The heat energy contained within the steam that passes through a turbine must be converted into mechanical energy. How this is achieved depends on the shape of the turbine blades. The two basic blade designs are: Impulse Reaction Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Types Of Blading:

Types Of Blading Impulse: Impulse blades work on the principle of high pressure steam striking or hitting against the moving blades. The principle of a simple impulse turbine is shown in Figure. Impulse blades are usually symmetrical and have an entrance and exit angle of approximately 20 0 . They are generally installed in the higher pressure sections of the turbine where the specific volume of steam is low and requires much smaller flow areas than that at lower pressures. The impulse blades are short and have a constant cross section. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Types Of Blading:

Types Of Blading Reaction: The principle of a pure reaction turbine is that all the energy contained within the steam is converted to mechanical energy by reaction of the jet of steam as it expands through the blades of the rotor. A simple reaction turbine is shown in Figure. The rotor is forced to rotate as the expanding steam exhausts the rotor arm nozzles. In a reaction turbine the steam expands when passing across the fixed blades and incurs a pressure drop and an increase in velocity. When passing across the moving blades the steam incurs both a pressure drop and a decrease in velocity A section of reaction type blading is shown in Figure Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine:

Steam Turbine Impulse stage Whole pressure drop in nozzle (whole enthalpy drop is changed into kinetic energy in the nozzle) Reaction stage Pressure drop both in stationary blades and in rotary blades (enthalpy drop changed into kinetic energy both i n stationary blades and in the moving blades in rotor) Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Impulse Stage:

Impulse Stage An impulse stage consists of stationary blades forming nozzles through which the steam expands, increasing velocity as a result of decreasing pressure. The steam then strikes the rotating blades and performs work on them, which in turn decreases the velocity (kinetic energy) of the steam. The stream then passes through another set of stationary blades which turn it back to the original direction and increases the velocity again though nozzle action. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Reaction Stage:

Reaction Stage In Reaction Turbine both the moving blades and the non-moving blades designed to act like nozzles. As steam passes through the non-moving blades, no work is extracted. Pressure will decrease and velocity will increase as steam passes through these non-moving blades. In the moving blades work is extracted. Even though the moving blades are designed to act like nozzles, velocity and pressure will decrease due to work being extracted from the steam. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Differences Between Impulse and Reaction Turbines:

Differences Between Impulse and Reaction Turbines This utilizes the principle of impulse and reaction. It is shown diagrammatically : There are a number of rows of moving blades attached to the rotor and an equal number of fixed blades attached to the casing. The fixed blades are set in a reversed manner compared to the moving blades, and act as nozzles. Due to the row of fixed blades at the entrance, instead of nozzles, steam is admitted for the whole circumference and hence there is an all-round or complete admission. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

3.0 Way of Compounding:

3.0 Way of Compounding Compounding of Impulse Turbine This is done to reduce the rotational speed of the impulse turbine to practical limits. (A rotor speed of 30,000 rpm is possible, which is pretty high for practical uses.) Compounding is achieved by using more than one set of nozzles, blades, rotors, in a series, keyed to a common shaft; so that either the steam pressure or the jet velocity is absorbed by the turbine in stages. Three main types of compounded impulse turbines are: a) Pressure compounded, b) velocity compounded and c) pressure and velocity compounded impulse turbines. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Pressure Compounding:

Pressure Compounding With pressure compounding the total steam pressure to exhaust pressure is broken into several pressure drops through a series of sets of nozzles and blades. Each set of one row of nozzles and one row of moving blades is referred to as a stage  This involves splitting up of the whole pressure drop from the steam chest pressure to the condenser pressure into a series of smaller pressure drops across several stages of impulse turbine. The nozzles are fitted into a diaphragm locked in the casing. This diaphragm separates one wheel chamber from another. All rotors are mounted on the same shaft and the blades are attached on the rotor. Pressure staging is also known as RATEAU staging. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Velocity Compounded Impulse Turbine:

Velocity Compounded Impulse Turbine When the velocity energy produced by one set of fixed nozzles is unable to be efficiently converted into rotational motion by one set of moving blades then it is common to install a series of blades as shown in Figure. This arrangement is known as velocity compounding. Velocity drop is arranged in many small drops through many moving rows of blades instead of a single row of moving blades. It consists of a nozzle or a set of nozzles and rows of moving blades attached to the rotor or the wheel and rows of fixed blades attached to the casing. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Pressure-velocity Compounded Impulse Turbine:

Pressure-velocity Compounded Impulse Turbine This is a combination of pressure-velocity compounding. Most modern turbines have a combination of pressure and velocity compounding. This type of arrangement provides a smaller, shorter and cheaper turbine; but has a slight efficiency trade off.  Turbines using this arrangement are often referred to as CURTIS turbines after the inventor. Individual pressure stages (each with two or more velocity stages) are sometimes called CURTIS stages. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Curtis stage:

Curtis stage This setup of a nozzle followed by a set of moving blades, non-moving blades, and moving blades makes up a single Curtis stage. After steam exits the nozzle there are no further pressure drops. However, across both sets of moving blades there is a velocity drop. This causes the Curtis stage to be classified as velocity compounded blading. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Turbines can be arranged either single cylinder or multi-stage in design. The multi-stage can be either velocity, pressure or velocity-pressure compounded (discussed as earlier. Single cylinder construction or Single Flow Turbine Single cylinder turbines have only one cylinder casing(although may be is multiple sections). Steam enters at the high pressure section of the turbine and passes through the turbine to the low pressure end of the turbine then exhausts to the condenser. Figure shows a single cylinder turbine with a high, intermediate and low pressure section contained within the one cylinder casing. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Tandem construction or Compound Flow Turbine Dictated by practical design and manufacturers considerations modern turbines are manufactured in multiple sections also called cylinders. Greater output and efficiency can be achieved by coupling a number of individual cylinders together in what is referred to as tandem (on one axis). Tandem compound Large electric power generating turbines commonly have a high pressure casing, which receives superheated steam directly from the boiler or steam generator. The high pressure turbine may then exhaust to an intermediate pressure turbine, or may pass back to a reheat section in the boiler before passing to a reheat intermediate pressure turbine. The reheat turbine may then exhaust to one or more low pressure casings, which are usually two exhaust flow turbines, with the low pressure steam entering the middle of the turbine and flowing in opposite directions toward two exhaust end before passing into the condenser. When the turbine casings are arranged on a single shaft, the turbine is said to be tandem compounded. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Tandem construction or Compound Flow Turbine A tandem two cylinder turbine with a single flow high pressure (HP) cylinder and a double flow low pressure (LP)cylinder is shown in Figure. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Tandem Three Cylinder Turbine It has a double flow LP cylinder with an IP cylinder arranged so that the steam flow through it is in the opposite direction to the HP cylinder. This design also greatly reduces the axial thrust on the rotor. Tandem three cylinder turbine is shown in Figure as under: Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Tandem Four Cylinder Turbine Large modern turbines are required to deliver high output and are generally constructed of four cylinders with the exhaust steam from the HP cylinder passing through are heater before entering the IP cylinder. Tandem Four cylinder turbine is shown in Figure as under: Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Tandem Cross-Compounding Turbine In cross compound turbines, the high-pressure, exhaust passes over to intermediate or low pressure casings which are mounted on separate shafts. The two shafts may drive separate loads, or may be geared together to a single load. In some larger overseas installations that operate at 60 hertz (frequency) the use of cross-compounding is some times employed. Cross-compounding is where the HP and IP cylinders are mounted on one shaft driving one alternator while the LP cylinders are mounted on a separate shaft driving another alternator. This is done so as the LP cylinder with its large diameter blading can be operated at a greatly reduced speed thus reducing the centrifugal force. Tandem cross-compounding turbine is shown in Figure: Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Cylinder arrangement:

Cylinder arrangement Tandem four cylinder turbine with reverse flow The final turbine arrangement that is becoming increasingly popular is the “Tandem four cylinder turbine with reverse flow HP cylinder, double flow IP and twin double flow LP cylinders”. This arrangement is shown in Figure: Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines 04. Number of Stages - Single stage - Multi-stage Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Stage:

Stage Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor In an impulse turbine , the stage is a set of moving blades behind the nozzle. In a reaction turbine , each row of blades is called a "stage." A single Curtis stage may consist of two or more rows of moving blades .

Classification of Steam Turbines:

Classification of Steam T urbines 5. Exhaust Conditions - Condensing - Extraction - Back-pressure Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam Turbines By steam supply and exhaust conditions : Condensing Extraction, (Automatic or controlled ) Non-condensing (back pressure), Mixed pressure (where there are two or more steam sources at different pressures), Reheat (where steam is extracted at an intermediate stage, reheated in the boiler, and re-admitted at a lower turbine stage). Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam T urbines Condensing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor The condensing turbine processes result in maximum power and  electrical generation efficiency from the steam supply and boiler fuel. The power output of condensing turbines is sensitive to ambient conditions. The cooling water condenses the  steam turbine  exhaust steam in the condenser creating the condenser vacuum. As a small amount of air leaks into the system when it is below atmospheric pressure, a relatively small compressor (Vacuum pump) or Air Ejector System removes non-condensable gases from the condenser.

Classification of Steam Turbines:

Classification of Steam T urbines Extraction Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor In an extraction turbine, steam is withdrawn from one or more stages, at one or more pressures, for heating, plant process, or feed water heater needs. They are often called "bleeder turbines .“ The steam extraction pressure may or may not be automatically regulated. Regulated extraction permits more steam to flow through the turbine to generate additional electricity during periods of low thermal demand by the CHP system. In utility type steam turbines, there may be several extraction points, each at a different pressure corresponding to a different temperature. The facility’s specific needs for steam and power over time determine the extent to which  steam  in an extraction turbine is extracted for use in the process.

Classification of Steam Turbines:

Classification of Steam T urbines Back-pressure Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Figure shows the non-condensing turbine (also referred to as a back-pressure turbine) exhausts its entire flow of steam to the industrial process or facility steam mains at conditions close to the process heat requirements.

Classification of Steam Turbines:

Classification of Steam Turbines 4. Rotational Speed - Regular - Low-speed - High-speed 5. Inlet steam pressure - High pressure (p>6,5MPa) - Intermediate pressure(2,5MPa <p<6,5MPa) - Low-pressure (p<2,5MPa) Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Classification of Steam Turbines:

Classification of Steam T urbines 8. Application - Power station - Industrial - Transport Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

TURBINE LOSSES:

TURBINE LOSSES In actual practice, not all of the energy in the steam is converted to useful work. Losses common to all turbines are described below: Loss of working substance . Loss of steam along the shaft through the shaft glands where the shaft penetrates the casing. Work loss. Loss due to mechanical friction between moving parts. Throttling loss. Wherever there is a reduction in steam pressure without a corresponding production of work, such as in a throttle valve . Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

TURBINE LOSSES:

TURBINE LOSSES Leaving loss . The kinetic energy of the steam leaving the last stage blading. This leaving loss can be minimized by lightly loading the last stage blading by increasing the annular exhaust area of the turbine. This is often optimized through economic studies. Windage loss . This is caused by fluid friction as the turbine wheel and blades rotate through the surrounding steam. Friction loss as the steam passes through nozzles and blading. Diaphragm packing loss as the steam passes from one stage to another through the diaphragm packing. Tip leakage loss in reaction turbines as steam passes over the tips of the blades without doing any useful work. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Thermodynamics of Steam Turbines:

Thermodynamics of Steam Turbines Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

TS DIAGRAM FOR RANKINE CYCLE:

TS DIAGRAM FOR RANKINE CYCLE Rankine cycle with superheat Process 1-2: The working fluid is pumped from low to high pressure. 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 vapor. Process 3-3': The vapour is superheated. Process 3-4 and 3'-4': The dry saturated vapor expands through a turbine, generating power. This decreases the temperature and pressure of the vapor, and some condensation may occur. Process 4-1: The wet vapor then enters a condenser where it is condensed at a constant pressure to become a saturated liquid. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Components And Relative Equipments:

Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Components And Relative Equipments:

Steam Turbine Components And Relative Equipments Foundation Rotor or Shaft Cylinder or Casing Blades Diaphragm Steam Chest Coupling Bearings Labyrinth Seal Front Pedestal TSI D-EHC (Governor) MSV (Main Steam Stop Valve) CV (Control Valve) IV (Intercept Valve) CRV (Combined Reheat Valve) Turbine Turning Gear Turbine Bypass & Drains Atmospheric Relief Diaphragm (Rupture Disk) Lube Oil System EHC Oil System Gland Steam System Condenser Steam Jet Ejector Vacuum Breaker Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Foundation or Frame:

Steam Turbine Foundation or Frame Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Surface Condenser Electrical Generator Exciter LP Turbine IP Turbine LP Turbine Lube Oil System Foundation

Steam Turbine Components And Relative Equipments:

Steam Turbine Components And Relative Equipments Frame (Base): S upports the stator, rotor and governor pedestal. Shell: Consists cylinder, casing, nozzles, steam chest & bearing. Rotor: Consists of low, intermediate, and high pressure stage blades, and possible stub shaft (s) for governor pedestal components, thrust bearing, journal bearings, turning gear & main lube oil system. Governor Pedestal: Consists of the EHC oil system, turbine speed governor, and protective devices Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Rotor:

Steam Turbine Rotor An multistage steam turbines are manufactured with solid forged rotor construction. Rotors are precisely machined from solid alloy steel forgings. An integrally forged rotor provides increased reliability particularly for high speed applications. The complete rotor assembly is dynamically balanced at operating speed and over speed tested in a vacuum bunker to ensure safety in operation. High speed balancing can also reduce residual stresses and the effects of blade seating. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

STEAM TURBINE ROTOR:

STEAM TURBINE ROTOR Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor IP Turbine LP Turbine HP Turbine

Turbine Casing:

Turbine Casing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments  The casings of turbine cylinders are of simple construction to minimize any distortion due to temperature changes. They are constructed in two halves (top and bottom) along a horizontal joint so that the cylinder is easily opened for inspection and maintenance. With the top cylinder casing removed the rotor can also be easily withdrawn with out interfering with the alignment of the bearings.

Turbine Casing:

Turbine Casing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Most turbines constructed today either have a double or partial double casing on the high pressure (HP) and intermediate pressure (IP) cylinders. This arrangement subjects the outer casing joint flanges, bolts and outer casing glands to lower steam condition. This also makes it possible for reverse flow within the cylinder and greatly reduces fabrication thickness as pressure within the cylinder is distributed across two casings instead of one. This reduced wall thickness also enables the cylinder to respond more rapidly to changes in steam temperature due to the reduced thermal mass.

Turbine Casing:

Turbine Casing The high-pressure end of the turbine is supported by the steam end bearing housing which is flexibly mounted to allow for axial expansion caused by temperature changes. The exhaust casing is centerline supported on pedestals that maintain perfect unit alignment while permitting lateral expansion. Covers on both the steam end and exhaust end bearing housings and seal housings may be lifted independently of the main casing to provide ready access to such items as the bearings, control components and seals. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Turbine Upper Casing:

Turbine Upper Casing HP Turbine Casing IP Turbine Casing LP Turbine Casing Atmosphere Relief Diaphragm HP Turbine Casing CV CV Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Turbine Lower Casing:

Turbine Lower Casing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Turbine Casing Flanges:

Turbine Casing Flanges One method of joining the top and bottom halves of the cylinder casing is by using flanges with machined holes. Bolts or studs are insertion into these machined holes to hold the top and bottom halves together. To prevent leakage from the joint between the top flange and the bottom flange the joint faces are accurately machined. A typical bolted flange joint is shown in Figure. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Turbine Casing Flanges:

Turbine Casing Flanges Another method of joining the top and bottom cylinder flanges is by clamps bolted radially around the outer of the cylinder. The outer faces of the flanges are made wedge-shaped so that the tighter the clamps are pulled the greater the pressure on the joint faces. This method of joining top and bottom casings is shown in Figure. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Blades:

Steam Turbine Blades Blade design is extremely important in attaining high turbine reliability and efficiency. A large selection of efficient blade profiles have been developed and proven by extensive field service allowing for optimal blade selection for all conditions of service. Blades are milled from stainless steel within strict specifications for proper strength, damping and corrosion resistant properties. Disk profiles are designed to minimize centrifugal stresses, thermal gradient and blade loading at the disk rims. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Components And Relative Equipments:

Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor 09HP Turbine Blades 07 IP Turbine Blades 05 LP Turbine Blades Rotary Blades Steam Turbine Components And Relative Equipments

Stationary Blade or Diaphragm:

Stationary Blade or Diaphragm Partitions between pressure stages in a turbine's casing are called diaphragms. They hold the vane-shaped nozzles and seals between the stages. Usually labyrinth-type seals are used. One-half of the diaphragm is fitted into the top of the casing, the other half into the bottom. Nozzle rings and diaphragms are specifically designed and fabricated to handle the pressure, temperature and volume of the steam, the size of the turbine and the required pressure drop across the stage. The nozzles used in the first stage nozzle ring are cut from stainless steel. Steam passages are then precision milled into these nozzle blocks before they are welded together to form the nozzle ring. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Stationary Blade or Diaphragm :

The nozzles in the intermediate pressure stages are formed from profiled stainless steel nozzle sections and inner and outer bands. These are then welded to a circular center section and to an outer ring then precision machined. The low-pressure diaphragms in condensing turbines are made by casting the stainless nozzle sections directly into high-strength cast iron. This design includes a moisture catching provision around the circumference which collects released moisture and removes it from the steam passage. Additional features such as windage shields and inter-stage drains are used as required by stage conditions to minimize erosion. All diaphragms are horizontally split for easy removal and alignment adjustment. Stationary Blade or Diaphragm Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Turbine Blade Fixing:

Turbine Blade Fixing Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Various root fixing shapes have been developed for turbine blading to suit both construction requirements and conditions under which turbines operate. The most popular types of blade root fixing available are: Grooves Straddle Rivet

Turbine Blade Fixing:

Turbine Blade Fixing Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Groove construction The groove type of root fixing fits into a machined grove around the circumference of the rotor wheel or disc. Some examples of typical groove type blade root designs are shown in Figure A while a rotor disc with a machined groove arrangement is shown in Figure B. Blade roots are installed through the closing blade window and then slid around the circumference of the disc into their desired position. The last blade root is installed in the closing blade opening and secured in position by dowel(s).

Turbine Blade Fixing:

Turbine Blade Fixing Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Straddle construction Straddle construction is where the blade root fits over the machining on the outer periphery of the rotor wheel or disc. An example of straddle fir-tree blade root construction is shown in Figure A. while the disc peripheral machining is shown in Figure B. Once again with this type of construction the blade roots are installed through the closing blade window slid around the circumference of the disc into position, then the last blade inserted is doweled in the closing blade window location.

Turbine Blade Fixing:

Turbine Blade Fixing Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Rivet construction Rivet construction is where the blade root either inserts into a groove or straddles the disc and all blades are doweled into position. Peripheral blade fixing On larger blading where the blade length is relatively long a system of lacing wire or shroud rings are installed to give the blading additional support and reduce vibration. The lacing wire is installed a small distance from the outer ends of the blades while the shoud rings are fitted to tangs on the outer edges of the blades and secured by peening the tangs. A section of blading showing the installation of the lacing wire is shown in Figure A while a section of blading showing shroud ring installation is shown in Figure B.

Steam Chest:

Steam Chest Steam chest : The steam chest, located on the forward, upper half of the HP turbine casing, houses the throttle valve assembly. This is the area of the turbine where main steam first enters the main engine. The throttle valve assembly regulates the amount of steam entering the turbine. After passing through the throttle valve, steam enters the nozzle block. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Coupling:

Coupling With multi-cylinder turbines it is necessary to have some method of connecting individual cylinder rotors. It is also a requirement to connect the turbine to the alternator rotor. To achieve these connections we use a device known as a coupling. These couplings must be capable of transmitting heavy loads and in some turbines are required to accommodate for axial expansion and contraction.  The types of couplings generally employed in power plants are: Flexible coupling Solid shaft coupling Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Coupling:

Coupling Flexible couplings Where axial shaft movement is required a flexible coupling is employed and these are either: Sliding claw (or tooth) Flexible connection (between the two flanges) With both of the above flexible couplings it is necessary to have a separate thrust bearing for each shaft to maintain the same relative position between rotor and cylinder casing. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Coupling:

Coupling Sliding claw (or tooth) Sliding claw couplings consists of an inner gears or tooth coupling half. The inner half is shrunk onto its respective shaft and secured by keys or driven pins. The outer coupling half; machined in the reverse shape is installed onto the other shaft.  The gear or teeth coupling is positioned inside the outer coupling half where it is able to slide back and forth to allow for expansion or contraction. A diagram of a sliding claw coupling prior to the inner claw section being inserted into the outer half is shown in Figure A, while a gear tooth coupling is shown in Figure B. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Coupling:

Coupling Flexible connection coupling Flexible connections such as the bibby coupling a re constructed in two halves. Each half is shrunk onto their respective shaft and secured with keys or driven pins. The halves are machined with groves parallel or nearly parallel to that of the alignment of the shaft. Flexible spring steel grids are inserted into these machined groves and held in place with an outer cover. This type of coupling is effective in allowing axial expansion and contraction along with the ability to tolerate minor misalignment. A bibby coupling  is shown in Figure.  The flexible couplings just mentioned are by no means the only flexible couplings available but they are the preferred choice for high load applications. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Coupling:

Coupling Solid shaft coupling When shaft movement is not required it is usual to install a solid type coupling. Two flanges are installed onto their respective shafts and then the two flanges are bolted together to form a solid joint as shown in Figure A. Often teeth are machined on the outer rim of these couplings and used as a point for barring the turbine shaft. (more about barring the turbine later). Figure B shows a solid shaft coupling with a barring gear fitted Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Components And Relative Equipments:

Turbine Bearings Journal Bearing: The turbine rotors are supported by two journal bearings. Both the No.1 and No.2 bearings are of a double-tilting pad type. The bearing metal is divided into six pads which are self-aligned. A center adjustment of these bearings can easily be made with shimmed pads. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

Turbine Bearings Journal Bearing Design Data: Bearing # Location Type Nominal dia in inches Nominal effective width in inches 1 HP DTP 15” 8” 2 LP DTP 18” 12” Note; D.T.P stands for Double Tilting Pad Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Components And Relative Equipments:

Turbine Bearings DOUBLE TILTING PAD TYPE JOURNAL BEARING Double tilting pad bearing provides maximum stability and freedom from shaft vibration. The tilting-pad design consists generally of six steel pads (shoes) with Babbitt linings on the bearing surface. The pads are installed on the inner of bearing ring, and can move radial and axial direction. Therefore, the pads Move smoothly, and maintain the correct alignment at all conditions. Hook fits in the inner of bearing ring retain the pads, and the pads are prevented from rotating by means of loose-fitting lock pins. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Components And Relative Equipments:

Turbine Bearings TAPERED-LAND THRUST BEARING The thrust bearing is located on the main shaft of the turbine. Independently mounted inside the standard, the thrust bearing absorbs the axial thrust of the turbine and generator rotors, which are connected by a solid coupling. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Components And Relative Equipments:

Turbine Bearings TAPERED-LAND THRUST BEARING T his tapered-land thrust bearing consists of two stationary thrust plates and two rotating Thrust collars on the turbine shaft which will provide the front and back faces to the bearing. These plates are supported in a casing so that they may be positioned against the rotating faces of the collars. The thrust collar faces are machined and lapped, producing smooth, parallel surfaces. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Thrust Bearing & General Bearing:

Thrust Bearing & General Bearing Thrust Bearing Thrust Bearing # 1 General Bearing General Bearing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

LABYRINTH SEAL:

LABYRINTH SEAL A  labyrinth seal  is a type of  mechanical seal  that provides a tortuous path to help prevent leakage. An example of such a seal is sometimes found within an  axle 's  bearing  to help prevent the leakage of the oil lubricating the bearing. A labyrinth seal may be composed of many  grooves  that press tightly inside another axle, or inside a hole, so that the fluid has to pass through a long and difficult path to escape. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

LABYRINTH SEAL:

LABYRINTH SEAL Labyrinth seals are utilized as end gland seals and also inter-stage seals. Stationary labyrinth seals are standard for all multistage turbines and grooves are machined on the rotating part to improve the sealing effect. The leakage steam from the outer glands is generally condensed by the gland condenser. Some leakage steam from the intermediate section of the steam end gland seals can be withdrawn and utilized by re-injecting it into the low-pressure stage or low- pressure steam line. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

Turbine front standard supports the No.1 bearing, thrust bearing and the front end of the turbine casing. Front standard is shaped like a box. Upper half of the standard can be disassembled at horizontal flange. A manhole located front of upper half is used oil strainer maintenance. This box is not only the bearing standard but control box which contains some important equipment. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor FRONT STANDARD & TSI Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

There are some instruments and button on the outside of the front pedestal cover. These are used for turbine operation and supervision. Some protective devices and speed detectors are installed inside the standard. Inside space of the standard is connected to oil tank and is kept slightly vacuum so that the oil drain or mist inside can not leak out. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor FRONT STANDARD & TSI Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

Lubricating oil is supplied from oil pipe which is located left side of front standard and flow out to oil tank through 1 ST journal and thrust bearings. Oil strainer is located up stream of bearing. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor FRONT STANDARD & TSI Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

Toothed-wheel for speed sensors The turbine rotating speed is sensed by the magnetic pickups faced to the toothed-wheel (96 teeth) installed on the control rotor. The pulse signal is produced when each tooth passes the pickups. The frequency signals from two (2) pickups are converted into digital value proportional to the turbine speed through F/D (Frequency to Digital) converters. Other three (3) sensors are located around toothed-wheel. These sensors are used for trip detector. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor FRONT STANDARD & TSI Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

The electromagnetic pickup use for speed detector is fixed facing the tooth face of the speed detecting gear connected directly to the rotor end of the turbine. (Inside of front standard) The turbine speed can be detected as the sine wave frequency signal in proportion to the turbine speed. This frequency signal is converted to an digital signal by means of the F/D converter to become a feedback signal to the speed control circuit. Over speed detector also make frequency signal in proportion to the turbine speed. They face to tooth-wheel on control rotor. Pickup is used eddy current type. Clearance between sensor face and tooth face is different from electromagnetic pickup type. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor FRONT STANDARD & TSI Steam Turbine Components And Relative Equipments

Turbine Supervisory Instrumentation (TSI):

Turbine Supervisory Instrumentation (TSI) Turbine Supervisory Instrumentation (TSI) or Turbine Supervision Equipment (TSE) is a generic term used in the power generation industry. TSI refers to instrumentation systems that specifically perform measurements of critical control parameters on large steam turbine generator trains. The size of the machines can range between 50–1200 MW and their age can often be in excess of 30 years. TSI systems are normally a mandatory requirement. The same technology is employed on other turbine types and in other industries, such as the hydrocarbon-processing sector. Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Supervisory Instrumentation (TSI):

Turbine Supervisory Instrumentation (TSI) Although the turbine is not readily accessible during operation, the turbine supervisory instrumentation is sufficient to detect any potential malfunction. The turbine supervisory instrumentation includes monitoring of the following: (1) Vibration and eccentricity (2) Thrust bearing wear (3) Exhaust hood temperature and spray pressure (4) Oil system pressures, levels, and temperatures (5) Bearing metal and oil drain temperatures (6) Shell temperature (7) Valve positions (8) Shell and rotor differential expansion (9) Shaft speed, electrical load, and control valve inlet pressure indication (10) Hydrogen temperature, pressure, and purity (11) Stator coolant temperature and conductivity (12) Stator-winding temperature (13) Collector air temperatures (14) Turbine gland sealing pressure (15) Gland steam condenser vacuum (16) Steam chest pressure (17) Seal oil pressure Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Supervisory Instrumentation (TSI):

Turbine Supervisory Instrumentation (TSI)

TSI Benefits:

TSI Benefits The use of, and experience with, TSI assists in reducing operating costs of the generation units by: • Reducing Turbine Roll Time: During the run-up and coast-down of large turbines, there are extensive soak periods to ensure stationary and rotating parts thermally expand equally. These periods are usually of a conservative length, but times can be further reduced with continuous and accurate measurement of key expansion clearances (and related parameters) available with TSI systems. • Time Between Overhauls: By using precise TSI measurement information, in an outage, the exact amount of work can be scheduled with reduced risk of unknown problems occurring after the overhaul is completed . Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

TSI Benefits:

TSI Benefits Diagnostic and Troubleshooting The trending of TSI data provides the user with the machine’s basic operating characteristics. Early detection of changes in trended data and comparison to normal conditions allows decisions to be made more quickly and inexpensively. More advanced analysis methods of this same raw data can diagnose problems like mass unbalance, misalignment, loose or broken parts, shaft cracks, seal rubs, and bearing instabilities caused by improper lubrication or bearing design. Early identification of these problems allows for corrections to be made at a time that is convenient to both the work force and system load. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

TSI Benefits:

TSI Benefits Automatic Shutdown Sometimes unanticipated problems arise quickly, however, TSI has the capability to limit damage to the machine and protect against total destruction or catastrophic failure. Confining damage flagged by vibration can make the difference between a two week outage and three to six months of down time. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments TSI Measurements TSI system measurements can be broken down into four major categories: Motion Measurements Eddy current (proximity) probes, case mounted velocity (seismic) transducers, shaft riders, and/or accelerometers can be used to monitor vibrations. Monitoring points may include vibration on main turbine generator and exciter, may also be used to measure rotor eccentricity.

TSI Measurements:

TSI Measurements Position Measurements Eddy current probes, LVDTs and linear/rotary potentiometers can be used to monitor thrust bearing wear, rotor position, casing (shell) expansion, differential expansion and control valve position. Speed Measurements Active or passive electromagnetic or eddy current probes can be used to monitor main turbine speed and acceleration, over-speed detection, zero speed detection. Process Measurements Thermocouples or RTDs can be used to monitor bearing white metal temperature, shell differential temperature, and lube oil temperature. Piezoelectric or strain gauge pressure transducers can be used to measure oil and hydraulic pressures. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

ARRANGEMENT OF SHELL THERMOCOUPLES :

ARRANGEMENT OF SHELL THERMOCOUPLES Thermocouples for water Induction   When water flows into the turbine due to an unexpected accident, there occurs a difference in temperature between the upper half and the lower half of the casing. As a result, (humped effect) phenomenon is generated on the casing, giving great damages to HP and IP casings, rotor blade, and thrust bearing. To detect any flow of water, therefore, thermocouples are provided at several positions of the upper and lower parts of the casing respectively to watch the difference in temperature between the upper and lower parts of the casing. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Thermocouples for Measuring Temperatures of Internal and External Surfaces of Casing:

Thermocouples for Measuring Temperatures of Internal and External Surfaces of Casing   At the time of cold starting of the turbine, there occurs a difference in temperature between the internal and external surfaces of casing with subsequent generation of thermal stress, which shortens the lives of turbine parts, To control the lives of turbine parts, a thermocouple is provided at each part of the casing for the purpose of carrying out life control for the parts. For the information on the fitting positions, see the thermocouples mounting drawings. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Components And Relative Equipments:

Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Principles Of Governing During operation of a Turbine-Generator Unit the Load carried by the Generator may vary over time. In order to respond to changing System Load demands the amount of steam directed to the Turbine must be varied in proportion to each demand.  The function of a governor is to provide rapid automatic response to load variations. STEAM TURBINE SPEED CONTROL

Steam Turbine Components And Relative Equipments:

Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments STEAM TURBINE SPEED CONTROL

Steam Turbine Components And Relative Equipments:

Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments STEAM TURBINE SPEED CONTROL The Speeder Gear of a Turbine Governor In order to maintain the system frequency constant and at the same time allow load variation to occur, it is necessary to be able to compensate for the loss of speed experienced with increasing load and the speed increase which accompanies load rejection. To achieve this a device is fitted in conjunction with the governor which effectively changes the speed-load characteristic of the turbine in such a way that speed effectively becomes independent of load. The device is known as the speeder gear.

Steam Turbine Components And Relative Equipments:

Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments STEAM TURBINE SPEED CONTROL Relays In all but the smallest turbine, it is necessary to use some means of amplifying the power of the governor in order to maintain a small sensing and control device and yet still have the motive force to position large sized throttle valves. The devices used as amplifiers are known as relays. The most common type of relay uses an oil system employing valve and a power piston. There are two types of these relays in use: Double acting Single acting

D-EHC (Digital Electro-Hydraulic Control System):

D-EHC (Digital Electro-Hydraulic Control System) System Features Application:  D-EHC system can be applied to control, protection and monitoring of steam turbines for various type of power plants including conventional fossil-fired power plants, combined cycle plants, co-generation plants, and atomic power plants. Powerful and reliable controllers: High-speed control with state-of-the-art microprocessor based control system Distributed and hierarchical architecture consists of; System controller,  Master controller, Programmable logic device, Valve interface Normal Operation: During Normal Operation, the main stop valves, intermediate stop valves and intercept valves are wide open. Operation of the T-G is under the control of the Electro-Hydraulic Control (EHC) System. The EHC System is comprised of three basic subsystems: the speed control unit, the load control unit, and the flow control unit. The normal function of the EHC System is to generate the position signals for the four main stop valves, four main control valves, and intermediate stop valves and intercept valves. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

D-EHC (Digital Electro-Hydraulic Control System):

Improved monitoring and operation ability: Windows-2000¨ based HMI (Human Machine Interface) and IES (Integrated Engineering System) Standard interface (RS232C Modbus, TCP/IP Ethernet, opc, etc.) with external systems Fully automatic turbine startup sequences turbine is automatically started based on start up sequence determined by inlet steam/turbine metal temperature miss-match, which enables optimum operation and longer equipment life. D-EHC (Digital Electro-Hydraulic Control System) Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

PowerPoint Presentation:

D-EHC System (Steam Turbine Startup) Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Auto Start Sequence Manual Start Steam Turbine Components And Relative Equipments

D-EHC (Digital Electro-Hydraulic Control System):

Turbine speed and Load Control Automatic Turbine Start-up control Line Speed Matching Control Full Arc admission (FA)/Partial Arc admission (PA) Transfer, if applicable Initial Pressure Regulator (IPR) Power Load Unbalance (PLU) Turbine Trip Function Turbine Trip Initiation (Primary overspeed, backup overspeed, EHC failure) Test Function (Valve Test, Overspeed Trip Test, Back up Overspeed Trip Test) Control and monitoring function of turbine generator auxiliaries Extraction Steam Pressure Regulation (if applicable) Thermal Stress Calculation TSI (Turbine Supervisory Instruments) monitoring Back up operation and monitoring at monitor panel of EHC cabinet Interface with Distributed Control System (DCS) Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor D-EHC (Digital Electro-Hydraulic Control System) Steam Turbine Components And Relative Equipments

Steam Turbine Components And Relative Equipments:

Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Steam Turbine Recommended Startup Time Chart:

Steam Turbine Recommended Startup Time Chart Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

MAIN STEAM STOP VALVE:

MAIN STEAM STOP VALVE The main stop valve is located in the main steam piping between the boiler and the outlet piping to turbine control valve chest in turbine casing. The main stop valve has one inlet and two identical outlet pipe connections. Outlet pipes are welded directory. The primary function of the main stop valves is to quickly shut off the steam flow to the turbine under emergency conditions such as failure of the control valves to close on loss of load. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

CONTROL VALVES (CV) :

CONTROL VALVES (CV) The control valves are arranged into an upper and lower valve group with each group mounted on common chest which is an integral part of the upper and lower turbine outer shells. Each control valve admits steam from the valve chest of its group to an individual nozzle box, after that controlled steam flow into a particular section of the turbine first stage nozzles. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

INTERCEPT VALVES:

INTERCEPT VALVES During starting and loading operation without turbine bypass system the intercept valves are operated fully opened for full arc admission starting. They remain fully open during transfer of steam flow control to the control valves, as well as all other periods of normal operation. The other side, when turbine bypass system is available for the starting up and loading. The intercept valves are used to control the steam flow to the intermediate turbine in conjunction with the control valves. After the turbine bypass operation is finished the intercept valves will be fully opened by EHC control system. The primary function of the intercept valve is pre-emergency protection: however, they also trip closed upon actuation of the emergency trip system. The secondary one is to control the steam flow during the starting and loading with turbine bypass system. The reheat stop valve is provided to quickly shut off the steam flow storage in the reheater line to the turbine under emergency condition. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

COMBINED REHEAT VALVES (CRV):

COMBINED REHEAT VALVES (CRV) Two combined reheat valves are provided, one in each hot reheat line. Supplying reheat steam to the turbine. As the name implies. The combined valve is actually two valve. The intercept valve and the reheat stop valve, incorporated in one valve casing. Although they utilize a common valve casing, these valves provide entirely different functions. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Turning Gear:

Turbine Turning Gear The motor driven turning gear is mounted on the turbine bearing cap, adjacent to the turbine-generator coupling so as to mesh with a bull gear (spacer disk gear type). Which is bolted between the turbine-generator coupling faces. The primary function of the turning gear is to rotate the turbine-generator shaft slowly and continuously during shutdown periods when rotor temperature changes occur. Turning Gear Driven Motor Turning Gear Driven Chain Turning Gear Turning Gear Oil Supply Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Turning Gear:

Turbine Turning Gear Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor When the turbine is shutdown, cooling of its inner elements is continues for many hours. If the rotor is allowed to remain stationary during this cooling period, distortion begins almost immediately. This distortion is caused by the flow of hot vapors to the upper part of the turbine casing, resulting in the upper half of the turbine being at a higher temperature than the lower half. The parts do not return to their normal position until the turbine has cooled to the point where both the upper and lower halves are at approximately the same temperature.

Steam Turbine Components And Relative Equipments:

Water induction can happen at any time; however the most common situations are during transients such as start up, shut down and load changes. In figure illustrates the percentage of times various events contribute to water induction for a conventional steam cycle. It is interesting that only 18 percent of water induction incidents occur when the unit is at load. Turbine drains are necessary to avoid slugging nozzles and blades inside the turbine with condensate on start-up; this can break these components from impact. The blades were designed to handle steam, not water. Turbine casing drains remove the condensate from the turbine casing during warm-up, securing, maneuvering and other low flow conditions. Steam Turbine Components And Relative Equipments Turbine Drains Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Drains :

Turbine Drains Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Turbine Water Induction Protection (TWIP) Turbine Water Induction Protection, often abbreviated as TWIP, is the broad category of equipment that is installed to prevent water damage to steam turbines. Any connection to the turbine is a potential source of water either by induction from external equipment or by accumulation of condensed steam. Steam turbine damage by water induction is a costly economic, safety and reliability concern. The American Society of Mechanical Engineers (ASME) formed a committee to address this issue, and the first standard was issued in 1972. ASME publication ASME TDP-1-1998 is titled “Recommended Practices for the prevention of Water Damage to Steam Turbines used for Electric Power Generation”. This practice covers the design, operation, inspection, testing, and maintenance of these systems. TWIP equipment is installed in the following power plant systems:

Steam Turbine Components And Relative Equipments:

In Figure shows a typical drain pot with redundant level elements. This configuration is typically used in "high risk" areas. One change in this standard that is shown is the level sensing device, which is labeled as a level element (LE). Drains should be installed at each low point in the motive steam piping. Drain Pots are recommended at the following locations to enhance condensate collection: Cold reheat line at first low point downstream of the steam turbine exhaust. (This application requires redundant level elements.) Motive steam lines that operate (admit steam to the steam turbine continuously) with less than 100°F (56°C) superheat unless a continuous drain has been provided. (This application requires redundant level elements.) Motive steam lines with attemperators - e.g. attemperator in HP steam line. The drain pot should be between the attemperator and the steam turbine. (This application requires redundant level elements.) Steam Turbine Components And Relative Equipments Turbine Drains Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Drains :

Turbine Drains Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Turbine Water Induction Protection (TWIP) 1. Main steam system, piping and drains 6. Turbine drain systems 2. Reheat steam systems, piping and drains 7. Turbine steam seal system, piping and drains 3. Reheat attemperating system 8. Main steam attemperator sprays 4. Turbine extraction systems, piping and drains 9. Start-up systems 5. Feedwater heaters, piping and drains 10. Condenser steam and water dumps. TWIP equipment is installed in the following power plant systems: Avoid discharging high-energy bypass steam into the area between the condenser hotwell and the tube bundle Locate the curtain spray and bypass sprayer a safe distance from the condenser tube bundles to allow a sufficient reduction in kinetic energy, so that high-energy steam does not reach areas above and below the tube bundles and cause a recirculation backflow with entrained water toward the turbine. Determine an incidence angle of high-energy steam jets that will avoid reflected velocity vectors toward the turbine exhaust.

Steam Turbine Components And Relative Equipments:

Water induction damage Water induction can damage steam turbines in several ways. The damage can be caused by the impact of large slugs of water or by the quenching effect of cold water on hot metal. The severity of water damage can vary from minor seal rubs all the way to catastrophic damage to the turbine.  Generally, water damage falls into the following categories: Thrust bearing failure Damaged blades Thermal cracking Rub damage Permanent warping distortion Secondary effects Secondary effects include items such as seal packing ring damage, pipe hangar and support damage, damage to instrumentation and controls, etc. Steam Turbine Components And Relative Equipments Turbine Drains Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Components And Relative Equipments:

Sources of water induction Water can be inducted into a steam turbine from several sources. The following are some of the most common sources of water: Motive steam systems Steam attemperation systems Turbine extraction/admission systems Feedwater heaters Turbine drain system Turbine steam seal system Start-up systems Condenser steam and water dumps (steam bypass) Steam generator sources Steam Turbine Components And Relative Equipments Turbine Drains Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Steam Turbine Components And Relative Equipments:

Turbine bypass systems should be provided with the same level of protection as motive steam piping. These should include drains and drain pots (if applicable) with power-operated drain valves. Attemperators in bypass systems that discharge to the cold reheat system (or any other line connected back to the steam turbine) should be designed to the same requirements on motive steam system attemperators. Non-return valves should be provided in the cold reheat system to prevent the reverse flow of bypass steam into the steam turbine. Designers should carefully consider the location, design and orientation of large steam dumps (such as turbine bypasses) into the condenser.  Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Turbine Bypass system

Atmospheric RELIEF DIAPHRAGM:

Atmospheric RELIEF DIAPHRAGM The atmospheric relief diaphragm is a safety feature which protects the exhaust hood and condenser against excessive steam pressure in case the condenser water for any reason is lost.   The device consists of hard rolled silver bearing copper sheet of sufficient area to pass full throttle steam flow at a safe protective pressure. In normal operation of the turbine with proper vacuum conditions, the diaphragm is dished inward against the supporting grid by atmospheric pressure should the vacuum conditions fail for any reason and the internal exhaust hood pressure raise to approximately 5 psig, it would force the diaphragm outward against the cutting knife. The diaphragm would be cut free as a disk relieving the exhaust pressure to atmosphere. Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Atmospheric RELIEF DIAPHRAGM:

Atmospheric RELIEF DIAPHRAGM Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments

Turbine Lube Oil System:

Turbine Lube Oil System Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Lube Oil System:

Turbine Lube Oil System Function The function of lubrication is to interpose a film of lubricant such as grease or oil between the moving surfaces in a bearing. Lubrication reduces friction, minimizes wear, provides cooling and excludes water and contaminants from bearing components. The protection of rotating heavy machinery depends greatly on the effective operation and supervision of lubricating oil systems and bearings. Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Lube Oil System:

Turbine Lube Oil System Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Establishment of Oil Film Oil lubricated bearings rely on the physical separation of the two bearing surfaces by a thin film or wedge of oil. In order to establish and maintain this oil film the following conditions must be established. 1) There must be relative motion between the two bearing surfaces to build up sufficient pressure within the oil to prevent the film breaking down. 2) There must be an uninterrupted supply of oil available to the bearing. 3) The bearing surfaces must not be parallel and need a narrow angle between them. This is to enable the oil to be shaped into a thin wedge tapering off in the direction of the motion

Turbine Lube Oil System:

Turbine Lube Oil System Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Oil Film Dynamics 1). With the shaft at rest the journal lies in the bottom of the bearing. The weight of the shaft tends to squeeze the oil out of the bearing so that metal to metal contact occurs. 2). As the shaft commences to rotate the first action of the journal is to climb up the bearing wall until it begins to slip and some metal to metal contact occurs. 3) As the shaft continues to increase in speed the oil is dragged around by virtue of viscosity until it forms a thin oil wedge. it's

Turbine Lube Oil System:

Turbine Lube Oil System Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Oil Film Dynamics 4) With the shaft now at final or rated speed the increased pumping action on the oil increases the journal internal oil pressure. This displaces the journal from the central position in the bearing enabling an ideal oil wedge to be created.

Turbine Lube Oil System:

Turbine Lube Oil System Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Components of a Turbine Lubricating Oil System Main Oil Tank Oil Purification Systems Oil Pumps  Oil Coolers Strainers / Filters Instrumentation  Jacking Oil Pumps Hydraulic Accumulator

Turbine Lube Oil System:

Turbine Lube Oil System Steam Turbine Components And Relative Equipments Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Turbine Gland Sealing:

Turbine Gland Sealing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments The purpose of the gland steam system is to reduce steam leakage to a minimum and to prevent air ingress. Or Function of the gland sealing system falls into two categories: Seal the turbine glands under all operating conditions Extract leak-off steam from the turbine glands.

Turbine Gland Sealing:

Turbine Gland Sealing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Steam leakage leads to the requirement for increased make up; this increases the load on the feed and  boiler  water treatment chemicals and to a deterioration of the working environment surrounding the power plant. Air ingress leads to a loss of vacuum and hence reduction in plant efficiency, and causes problems of thermal stressing around the gland as well as increases oxygen content of the exhaust steam.

Turbine Gland Sealing:

Turbine Gland Sealing Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Steam Turbine Components And Relative Equipments Gland Steam Condenser The gland steam condenser is cooled by the condensate extracted from the main condenser and so acting as a feed heater. The gland steam often shares its condenser with the air ejector reducing the cost of having two units. A fan is fitted to induce a flow through the system without incurring a negative pressure in the final pocket as this would allow the ingress of air. This is ensured by the fitting on valves to the exhaust line from the glands so enabling the back pressure to be set.

Condenser:

Condenser Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor A  surface condenser  is a commonly used term for a water-cooled  shell and tube heat exchanger  installed on the exhaust  steam  from a steam turbine  in  thermal power stations . These  condensers  are  heat exchangers  which convert steam from its gaseous to its liquid state at a pressure below  atmospheric pressure . Where cooling 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 exhaust pressure as a water-cooled surface condenser.

Vacuum System:

Vacuum System Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor For water-cooled surface condensers, the shell's internal vacuum is most commonly supplied by and maintained by an external  steam jet ejector  system. Such an ejector system uses steam as the motive fluid to remove any non-condensable gases that may be present in the surface condenser. The Venturi effect , which is a particular case of  Bernoulli's principle , applies to the operation of steam jet ejectors. Motor driven mechanical  vacuum pumps , such as the  liquid ring type, are also popular for this service. Steam Jet Air Ejector

Vacuum System:

Vacuum System Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Vacuum System:

Vacuum System Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Vacuum Breaker The purpose of a Vacuum Breaker Valve is to quickly allow air into the vacuum space of the condenser and low pressure turbine exhaust hood. The vacuum breaker valve is usually located on the steam turbine or the condenser shell/transition. A vacuum breaker valve is typically operable by a controller responsive to losses of load on the steam turbine. Once opened, the vacuum breaker valve will allow air into the steam space to quickly reduce the existing vacuum and hence reduce the acceleration of the steam turbine upon loss of load by the generator.

Turbine Protections:

Turbine Protections Emergency trip pushbutton in control room Boiler Trip, Turbine trip Low condenser vacuum Low lube oil pressure LP turbine exhaust hood high temperature Thrust bearing wear Emergency trip at front standard Low hydraulic fluid pressure Loss of EHC Excessive turbine shaft vibration Loss of two speed signals - either Normal Speed Control or Emergency Over speed Trip Over Speed Trip 1 Over Speed Trip 2 Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

Break-downs could happen… When Protection Not Operated:

Break-downs could happen … When Protection Not Operated Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor

PowerPoint Presentation:

Thanks Prepared by Mohammad Shoeb Siddiqui Senior Shift Supervisor Saba Power Plant Pakistan shoeb.siddiqui@sabapower.com shoeb_siddiqui@hotmail.com shoeb_siddiquipk@yahoo.com

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