Download Supervisor-Power Plant Operations

Basic Power Plant Operation
2014 NA PGS Technical Leadership Training
1
Objectives
• Explain how a turbine works
• Discuss the principles of operation for
Steam Turbine and Gas Turbines
• Describe the operation of a Combined Cycle
Power Plant
• Discuss how Generators make electricity
• Discuss factors that affect maintenance
cycles
Conservation of Energy
• The law of conservation of energy states
that energy can be neither created nor
destroyed. However, energy can change
forms, and energy can flow from one place
to another.
• The flow of heat is a form of energy
transfer.
• Work is a process of transferring energy to
or from a system.
What Makes a Turbine Spin?
Why are Turbines Shaped This Way?
Gas Turbine
Gas Turbine History
• 1791: first patent for a gas turbine
resembling present day units was issued
• Manufacture of a gas turbine that could
efficiently provide useful power was not
attainable until high temperature materials
became available
• 1949: GE placed its first gas turbine into
commercial operation
Brayton Cycle
• The Brayton cycle is the thermodynamic
cycle that describes the workings of a
constant pressure heat engine.
• There are 3 processes:
– Compression
– Combustion
– Expansion
Gas Turbine Plant Layout
Thermal Efficiency
• Ratio of work extracted from hot gas to the
heat that is added.
• How much of the available energy did the
turbine use?
Naming Convention
• Frame Size (3,5,6,7,9) denotes the size railcar
that the machine will ship on.
• Number designation is the number of shafts
the machine has (i.e. MS5001 has one shaft)
• Letter designations indicate horsepower (due
to increased firing temp), increasing from A.
• Incremental design changes are indicated by
additional letters (6FA, 6FB)
Steam Turbine
Steam Turbine History
• 1882: Thomas Edison put the central station
power system into operation, using a
steam-piston engine as the prime mover ->
fairly efficient
• 1896: Charles Curtis designed a more
efficient system to drive a generator and
offered his invention to GE in Schenectady > steam turbine
• 1901: GE offered its first turbine for sale
Rankine Cycle
• The Rankine cycle is the thermodynamic
cycle of a heat engine that converts heat
into mechanical work.
• There are 4 processes:
– Wpump : energy added by the feedpump
– Qin : heat transferred into the system
– Wturbine : energy extracted by the turbine
– Qout : heat transferred out by the condenser
Basic Steam Plant Layout
High Temp
Low Pressure
High Temp
High Pressure
Low Temp
High Pressure
Low Temp
Low Pressure
Thermal Efficiency
• Ratio of work extracted from steam to the
heat that is added.
• How much of the available energy did the
turbine use?
Naming Convention
• Letter Designator (A,B,C,D) determined by basic characteristics:
– Full or half speed
– Tandem or cross-compounded
– Number of low pressure flowpaths
– Reheat or non-reheat
• Variation within basic characteristics results in a new code
(1,2,3)
– Position of valves
– Position of crossovers
– Types of nozzles
– HP-IP in separate or same shell
• Suffix is included if further differentiation is needed (A,D,E,H,R,X)
D11H
D – Full speed, reheat, double-flow
condensing turbine
11 – Off-shell valves, single shell high
pressure section with diaphragm first stage
H – Special low pressure section designed for
high back pressure applications
Combined Cycle Power Plant
General Description
• Uses the Gas Turbine Brayton Cycle in
combination with the Steam Turbine
Rankine Cycle
• GE Trade name is STAG (STeam and Gas).
Most common configuration is S207FA.
• Used to increase overall plant efficiency.
AC Generator
Electricity Basics
• Voltage: a measure of how strongly the
electrons are being pushed through a
conductor
• Current: a measure of the rate of electron
flow through a conductor
Voltage Induction
• Three things are necessary to induce a
voltage:
– Magnetic Field
– Current Carrying Conductor
– Relative Motion Between the Two
Generator Excitation
• Generator Excitation System either:
– Takes part of generator AC output and rectifies
it to DC to supply the generator field windings,
or
– Takes power from the Grid and rectifies it to DC
to supply the generator field windings
• Applying a voltage to the generator rotor
turns it into a large electro-magnet
Stator Cooling
• Electricity flowing through a generator
creates a great deal of heat, which must be
removed.
• Three methods:
– Air Cooling
– Hydrogen Gas Cooling
– Liquid Cooling
Hydrogen Seals
Maintenance Considerations