STEAM TURBINE POWER PLANT TRAINING COURSE DESCRIPTIONS
The objective of this module, the first in the series on "Steam Power and Cogeneration" is to present the different cycle arrangements that are commonly employed in steam turbine power generation installations.
Energy concepts and steam fundamentals are also reviewed to improve understanding and provide examples of efficiency calculations. Finally, to prepare the way for the remainder of the module, an introduction is made to the major systems of the steam power plant and their functions.
After completing this module, the participant should be able to understand the following concepts and apply them in day-to-day work activities:
• Co-generation arrangements
• Heat recovery from diesels and gas turbines
• Back pressure steam turbines
• Energy utilization
• Balance of heat and power demand
• Condensing turbines
• Condenser loss
• Units of absolute pressure, vacuum
• Feedwater heating
• Extraction steam for process
• Forms of energy; heat, mechanical, electrical
• Properties of steam and water
• Sensible heat, latent heat, superheat
• Effect of pressure on saturation temperature
• Use of steam tables
• Heat and efficiency calculations for different cycles
• Effect of operating conditions on efficiency
• The reheat cycle
• The use of temperature-entropy charts
• Function of major plant systems
1. main and auxiliary steam
2. turbine extraction steam
3. condenser circulating water
4. condensate and feedwater systems
5. feedwater heaters
6. boiler and combustion systems
7. boiler air and gas systems
8. fuel supply systems
9. turbine support systems
10. generator support systems
11. monitoring and control systems
12. station service supply systems
The objective of this second module is to look at the concept of steam generation, and to present features of design and construction of boilers (steam generators). Both the water side and gas side of the boiler are dealt with, but the subject of combustion and burner equipment is left to the next tape.
After completing this module, the participant should be able to understand the following concepts and apply them in day-to-day work activities.
• The requirements for a basic boiler.
• The fire-tube boiler.
• Convection, natural circulation, and forced circulation.
• The need for feedwater to compensate for steam generated.
• Basic control of steam pressure, i.e. steam output flow versus heat input from combustion.
• Water-wall construction.
• The use of downcomers to feed riser tubes.
• Shrink and swell of water level.
• Heat transfer by radiation and conduction.
• The function of the steam drum.
• Steam drum internal hardware.
• Steam drum external connections.
• Boiler drains and blowdown valves.
• Superheater arrangements.
• Pendant and horizontal superheater construction.
• Superheater drains.
• Primary and secondary superheater banks.
• Attemperation for steam temperature control.
• Reheat bank arrangements.
• The air and gas path through the boiler.
• FD fans and ID fans.
• Comparison of balanced draft system and the pressurized furnace.
• Temperature gradient throughout the air and gas path.
• Function of the economizer and airheater.
• Boiler insulation and boiler casing.
• Access ports and doors.
• Typical construction of the heat recovery steam generator (HRSG).
• Sources of hot gas for the HRSG.
• Bypass damper arrangements.
• The multiple pressures HRSG
The objective of this third module is to present the characteristics of different types of fuel, and look at the factors governing efficient combustion.
Various types of burner equipment are demonstrated for burning coal, oil, natural gas, wood, and low-grade fuels such as municipal waste.
On completion of this module, the participant should understand the following concepts and be able to apply them in day-to-day work activities.• Combustible elements in fuel.
• Non-combustible elements in fuel.
• Typical analysis for coal, oil, natural gas and wood.
• Combustion reactions for carbon, hydrogen, and sulfur.
• Calculation for heat content of different fuels.
• Fuel requirements (quantity) to meet energy demand on boiler.
• Oxygen requirements for combustion of different fuels.
• Theoretical air requirements.
• Need for excess air.
• Flue gas analysis.
• Formation of carbon monoxide; effect of nitrogen.
• Monitoring oxygen (O2) in flue gas.
• Losses due to moisture in fuel gas.
• Significance of lower caloric value (LCV) and higher calorific
• Value (HCV).
• Conditions required for combustion in practice. Temperature, turbulence and time.
• Firing fuel oil and gas.
• Firing with pulverized coal.
• Bottom ash and fly ash removal.
• Solid-fuel firing on a grate.
• Firing low grade fuels.
• Fluidized bed combustion.
The objective of this module is to present the major features of boiler operation. Start-up, shutdown, and on-load conditions are dealt with, including a discussion on potential hazards and boiler protection devices.
After completion of this module, the participant should be able to understand the following concepts and apply them in day-to-day work activities.
• Start-up procedure.
• Factors controlling pressure raising.
• Operation of drains and vents.
• Shutdown procedure.
• Standby condition.
• On-load operation.
• Steam pressure and temperature control.
• Efficient combustion control.
• Monitoring O2, CO and excess air.
• Effects of sulfur in fuel.
• Combating low temperature corrosion.
• Ash related problems, slagging.
• High temperature vanadium corrosion.
• Typical monitoring points on the boiler.
• Operator’s interface.
• Boiler operating hazards.
• Protection equipment, alarms and trips.
The objective of this fifth module is to focus attention on the areas of control which are essential for successful boiler operation including; automatic controls, boiler water conditioning, and environmental control.
On completion of this module the participant should understand the following concepts and apply them in day-to-day activities.
• The basic control loop
• Control signals; analog and digital
• Typical control system logic:
1. Combustion control
2. ID Fan Control
3. Steam temperature control
4. Drum level control
• Auto-manual change over
• The need for boiler water conditioning
• Scale deposits and their causes
• Continuous blowdown
• Phosphate addition
• Causes of carryover
• Effects of silica in boiler water
• Causes of internal corrosion
• pH control; caustic addition
• Congruent phosphate control
• Removal of O2 and CO2 from feedwater
• Oxygen scavenging; hydrazine
• Source of boiler pollutants
• Environmental effects of pollutants
• Pollution control equipment to reduce emissions of particulates, SOx, NOx
• Treatment of liquid effluents and solid waste.
The objective of this module is to present the major features of STEAM TURBINE construction, and support systems. Techniques of operation and control equipment are demonstrated and discussed in the next module.
On completion of this module the participant should be able to understand the following concepts and apply them in day-to-day work activities.
• Major components of the steam turbine.
• Conversion of heat energy (in steam) to rotating mechanical energy.
• Stationary and moving blades.
• Impulse and reaction blading.
• Steam conditions at turbine exhaust.
• Increase in specific volume of steam at low pressure.
• Typical multi-cylinder arrangements.
• Location of support bearings.
• Function of the thrust bearing.
• Allowance for expansion of rotor and casing.
• Rotor construction, disks and blades.
• Diaphragms and fixed blades.
• Turbine assembly.
• Function of shaft gland seals.
• Gland steam leak-off and supply system.
• Interstage seals.
• Typical lube oil circulation system.
• Need for continuous lube oil cooling and cleaning.
• Standby oil pumps A.C. and D.C..
• Hydraulic oil application.
• Combined lube and hydraulic oil system.
• Function of the condenser and location.
• Condenser mechanical arrangements.
• Fouling of condenser tubes and tube plate.
• Water box siphon system.
• Effect of air leakage into the condenser.
• Removal of air and incondensable gases from the condenser by vacuum equipment.
• Function of the steam ejector for start-up and on-line operation.
The objective of this seventh module is to present and discuss the major features of steam turbine operation, protection and control. Particular attention is paid to the effect of changes in load or steam temperature on mechanical operation of the turbine, and consequent need for supervisory instrumentation and automatic protection devices.
After completion of this module the participant should be able to understand the following concepts and apply them in day-to-day operation:• Operation of the turbine hydraulic control system.
• Governor operation.
• The function of turbine control valves and stop valves.
• The function of reheat intercept valves and reheat stop valves.
• Location of steam chest(s).
• Operation of drains on steam piping, stop valve, steam chest, turbine shell.
• The need for turning gear.
• Start-up procedure.
• Limitations to rate of raising speed.
• Critical speeds.
• Full-arc and partial arc steam admission.
• Matching steam temperature to turbine metal temperature.
• Turbine steam by-pass.
• Minimum load requirements.
• Effects of turbine expansion.
• Supervisory equipment: eccentricity, vibration, differential expansion, metal temperature, shaft position, pedestal position.
• Prevention of water ingress to the turbine.
• Function of protection devices, overspeed, low vacuum, thrust bearing failure, loss of lube oil pressure, boiler-generator-turbine intertripping, steam pressure deloader.
• Turbine trip function.
• On-load testing of protective devices.
• Exercising stop valves.
• Control room layout.
• Significant monitoring points.
The objective of this eighth module is to draw attention to important operating parameters of the POWER GENERATOR. A review of fundamentals is included as an aid to understanding the significance of generator control.
After completion of this module, the participant should be able to understand the following concepts and apply them to his day-do-day work activities:• The generator's function: energy conversion.
• Features of generator construction.
• Stator winding, rotor winding.
• Static exciter, collector rings, rotating exciter.
• Open cycle air cooling.
• Closed cycle air cooling.
• Advantages of hydrogen cooling.
• Hydrogen pressure control, leakage compensation.
• Hydrogen seals, seal oil system.
• Hydrogen explosive range.
• Procedures for purging.
• Fundamentals of AC generation.
• Relationship between frequency, speed, and number of poles.
• Single phase and 3-phase generation.
• 3-phase system.
• Required conditions for synchronizing.
• Controlling generator power output.
• Combined operation of governors.
• Load sharing between parallel generators.
• Static excitation system.
• Brushless excitation system.
• Effect of changing excitation current.
• Control of voltage and MVAR output.
• System demand for MVARs.
• Generator MVA output.
• Power factor.
• Generator capability curve.
The objective of this module is to present and discuss typical arrangements of plant systems and auxiliary equipment, all of which fulfil a specific function and need in power plant operation.
After completion of this module the participant should be able to understand and apply the following concepts in day-to-day operation:• Typical arrangements of steam systems including main steam, reheat steam, extraction steam, and auxiliary steam.
• Procedure for warming and charging a steam line.
• Operation of steam line drains, and traps.
• Allowance for expansion in pipe routing and configuration.
• Applications of extraction steam.
• Routing of extraction steam line drains.
• Sources and applications of auxiliary steam.
• Pressure reducing stations and desuperheating stations.
• The function of the condensate and feedwater system.
• Addition of heat to condensate and feedwater.
• Pumping arrangements, i.e. condensate pump and boiler feedpump.
• Control of feedwater flow to boiler, i.e. variable speed drive or modulating feedwater control valve.
• Feedwater control valve arrangements.
• Feedwater pump recirculating line.
• Procedures for preparing a feedwater pump for stand-by service.
• Hotwell level control by make-up or overflow.
• Control of deaerator level.
• Function of the condensate fill pump (also known as boiler fill pump).
• Construction and operation of closed feedwater heaters.
• Venting arrangements from feedwater heaters.
• Routing and control of condensate drains from closed heaters.
• Protection against high-level condensate in feedwater heaters.
• The function and operation of the deaerator.
• Venting of pipework and equipment before start-up.
• Typical arrangements and characteristics of:
1. Closed circuit bearing cooling water system.
2. Circulating water (CW) systems.
3. Service water systems.
4. Fire protection systems.
• Auxiliary plant power supply bus arrangements.
• Sources of station service supply.
• Black start capability and capacity.
• Procedures for transfer of station service supply on unit trip.
• Typical arrangement for supply and application of DC power.
• UPS systems.
The objective of this module is to present and discuss the various types of maintenance that must be carried out in a steam power plant. We also look at documentation, which is required for planning and control of maintenance. Also demonstrated are typical maintenance tasks that are normally performed on major items of equipment during plant inspection outages and major overhauls.
After completion of this module, the participant should be able to understand the following concepts and apply them in day-to-day work activities.• The objectives of maintenance, namely to retain equipment availability, capability and efficiency.
• The definition and relationship of different types of maintenance such as running maintenance, preventive maintenance, major overhaul, predictive maintenance, and breakdown maintenance.
• Typical running maintenance activities.
• The principals of preventive maintenance, i.e. regular scheduled inspection and replacement of components where necessary.
• The application of predictive maintenance through condition monitoring.
• Condition monitoring techniques, on line and off line.
• The application of NDE (Non-Destructive Examination) techniques.
• Reliability centred maintenance.
• The effect of operating regime on equipment deterioration.
• The need for planning, control and co-ordination of maintenance activities.
• Typical documentation, which is used for maintenance control.
• The critical importance of recording measured values during overhaul inspection.
• The need to keep the equipment history file updated.
• Spare parts data.
• Flexibility of the maintenance schedule.
• Typical boiler maintenance activities, during operation and during overhaul.
• Boiler predictive maintenance activities.
• Boiler internal inspection.
• Maintenance of boiler auxiliary equipment.
• Typical outage schedule for turbine maintenance.
• Turbine condition monitoring activities.
• Typical maintenance activities during turbine overhaul.
• Maintenance of turbine auxiliary equipment.
• Generator running maintenance activities.
• Generator overhaul activities.
• Generator condition monitoring.
• Typical transformer maintenance activities.
• Typical switchgear maintenance activities.
The objective of this module is to present the principles and practice of C.H.P. (Combined Heating and Power) systems. Utilizing heat recovery from different types of prime mover including steam turbines, gas turbines, and diesel engines. In addition to heat recovery equipment, typical district heating distribution systems are also discussed.
On completion of this module, the participant should understand the following concepts and be able to apply them in day-to-day work activities.
• Typical values of heat loss from different types of prime mover.
• Heat recovery from extraction steam turbines.
• Heat recovery from backpressure turbines.
• Heat balance and overall heat utilization with heat recovery.
• Heat recovery from gas turbines.
• Combined cycle ? gas turbine and steam turbine, with extraction steam for district heating.
• The application of auxiliary burners to HRSGs.
• Heat recovery from reciprocating engines.
• Fluid heat exchangers.
• Exhaust duct economizer.
• The application of auxiliary boilers for process or district heating.
• The primary hot water distribution loop, supply and return.
• Control of district heating (D.H.) supply temperature.
• Control of engine jacket coolant temperature.
• The customers’ energy transfers station.
• Control and metering of customer’s heat consumption.
• Installing pre-insulated piping, including alarm and control wiring.
• The characteristics of steam distribution for district heating.
• Steam piping and hardware.
• Types of valves installed on a steam system.
• Procedures for handling condensate forming in steam lines:
1. During start-up.
2. While in service.
• The causes and dangers of water hammer.
• The need for caution when interconnecting a small private co-generator (C.H.P.) into a large utility power system.
• The need for compatibility of voltage control equipment, governor control, and protection equipment.
• The need for coordination of clearance procedures between the utility and the private generator to prevent hazards to personnel.
• The need for coordination of automatic and manual switching procedures.
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