Combined Cycle Power Plant Operations Training

582-01 Combined Cycle Power Plants

When you complete this lesson, you will be able to describe the basic thermal cycles of a combined cycle power plant, including topping and bottoming cycles. You will also be able to list advantages and disadvantages of various combined cycle configurations and define common terminology associated with combined cycle operations.

  • Explain the thermal cycles of combined cycle plant
  • Describe a combined cycle plant “topping” cycle
  • Describe a combined cycle plant “bottoming” cycle
  • List advantages of a combustion turbine-water/steam combined cycle system
  • Compare combined cycle plant efficiencies with the efficiencies of simple cycle plants
  • Describe the way that simple cycle efficiencies can be increased
  • Define cogeneration and IGCC
  • Describe the effects of combustion air cooling and supplemental HRSG firing
  • Explain the difference between a single shaft and multi-shaft combined cycle configurations
  • Describe the use of single pressure and multi-pressure steam cycle designs

582-02 Combined Cycle Power Plant Components

When you complete this lesson, you will be able to identify and describe the major components of a combined cycle power plant.

  • Describe the design and operating principles of a combustion turbine used in a combined cycle application
  • Describe the design and operating principles of a heat recovery steam generator used in a combined cycle application
  • Describe the design and operating principles of an electrical generator used in a combined cycle application
  • Describe the purpose of a stack damper on combined cycle units
  • Explain the use of supplementary firing in heat recovery steam generators
  • Be able to explain the natural and forced circulation in the steam production process
  • Explain the purpose of selective catalytic reduction and carbon monoxide catalyst systems in the operation of a combined cycle power plant
  • Be able to explain the purpose of reheat steam

582-03 HRSG – Flow Path and Major Equipment

When you complete this lesson, you will be able to identify and describe the major components and flow paths of a HRSG.

  • Recall the function of a HRSG
  • Describe the purpose of the economizer in a HRSG
  • Describe the purpose of the evaporator in a HRSG
  • Describe the purpose of the steam drum in a HRSG
  • Describe the purpose of the superheater in a HRSG
  • Outline the flow path of the combustion gas through the HRSG
  • Outline the flow path of the water/steam through the HRSG
  • Explain the relationship of water flow vs steam flow

582-04 HRSG – Auxiliary Equipment and Systems

When you complete this lesson, you will be able to identify some auxiliary systems that may be found in a HRSG and recall their purpose and benefit to the unit.

  • Recall the purpose of the following systems:
  • Supplementary firing
  • Bleed Air
  • Deaerator
  • Attemperator
  • Sampling
  • Dosing
  • Selective Catalytic Reduction (SCR)
  • CO catalyst
  • Nitrogen
  • Identify the general location of the following systems:
    • Supplementary firing
    • Deaerator
    • Selective Catalytic Reduction (SCR)
    • CO catalyst
  • Relate the operating conditions in which supplementary firing would be impactful
  • Describe the mechanism by which deaerators fulfill their purpose
  • List some qualities for which analyses are frequently performed in the steam/water cycle
  • State why SCR systems and CO catalyst systems have been put in place
  • Relate what operating conditions a nitrogen system would be used in

582-05 HRSG - Basic Operating Concerns and Conditions

When you complete this lesson, you will be able to describe the steps to startup and shutdown the HRSG, and the steps to confirm it is operating normally. Additionally, conditions that may cause concern during operation will be covered.

  • Explain important steps during startup, shutdown, and normal operations
  • Explain the need for maintaining steam flow during the startup process
  • State why the operating environment of the HRSG is important
  • Describe why the use of vents and drains ensures steam quality
  • Identify what shutdown conditions would modify the shutdown procedure
  • Recall why and how pressure and temperature affect the life expectancy of the HRSG
  • Explain how pressure is created during the steam production process
  • Explain how pressure and temperature are controlled in the steam systems
  • Define cycling
  • Identify what components are most susceptible to failure when cycling
  • Explain and define:
    • Stress corrosion cracking
    • Fatigue corrosion cracking
    • Thermal fatigue
    • Creep

582-06 Combined Cycle Steam and Feedwater Operating Principles

When you complete this lesson, you will be able to describe the feedwater and steam flowpaths in a typical combined cycle power plant. You will also be able to explain the HRSG design principles governing plant operation.

  • Describe the system flow path of a basic single-pressure cycle
  • Describe the function of the following components of a HRSG:
    • Economizer
    • Evaporator
    • Superheater
  • Explain the concept of a pinch point
  • Describe the system flow path of a dual-pressure (HP and LP) cycle
  • Describe the system flow path of a triple-pressure (HP, IP, and LP) cycle
  • Explain the purpose of a pegging steam line
  • Describe the system flow path of a triple-pressure cycle with reheat
  • Explain the operation of a HRSG feedwater pump
  • Describe the function of a steam attemperator

582-07 Combined Cycle Condensate and Circulating Water Systems

When you complete this lesson, you will be able to explain the flow paths of the condensate and circulating water systems and describe their major components. You will also be able to explain the design principles governing the operation of these systems.

  • Describe the purpose of the Condensate System in a combined cycle plant
  • Explain the operation of a Water-Cooled Condenser
  • Explain the operation of an Air-Cooled Condenser
  • Describe the purpose of a steam jet air ejector, vacuum pump, and hogger
  • Describe the function of a deaerator
  • Describe the common deaerator arrangements used in combined cycle power plants
  • Explain the difference between a once-through and a closed-circuit circulating water system
  • Describe the purpose of a cooling tower in a combined cycle circulating water system

582-08 Combined Cycle Auxiliary Systems

When you complete this lesson, you will be able to describe the function and operation of the auxiliary components and systems found in a typical combined cycle power plant.

  • Describe the function of the Closed Cooling Water System
  • List the typical heat loads cooled by the auxiliary cooling water system
  • Explain the reason for maintaining chemistry control of boiler water
  • Describe the common methods of HRSG chemistry control, including the following:
    • All volatile treatment
    • Phosphate treatment
    • Caustic treatment
  • List the common parameters monitored by the water treatment, sampling, and analysis systems

582-10 Steam Turbines in a Combined Cycle Plant

When you complete this lesson, you will be able to describe the basic components of a steam turbine and explain their purpose in relation to a combined cycle power plant. In addition, you will be able to identify common turbine auxiliaries and describe basic steam turbine operations.

  • Describe the energy conversions that take place between the HRSG and steam turbine
  • Recall the steam flow path through a high, intermediate, and low-pressure turbine
  • Identify the purpose of the following steam turbine valves:
    • main steam stop valves
    • turbine governor and control valves
    • reheat and intercept valves
  • Identify the difference between full arc admission and partial arc admission