Course objective

• Mechanical power is produced by a heat engine that transforms thermal energy from combustion of a fuel  into rotational energy
• heat generated in the furnace is transmitted to the boiler where water forced into the boiler by the feed pump is converted into steam
• steam drives turbine blades shaft
• the efficiency of a steam turbine is limited by the maximum temperature of the steam produced and is not directly a function of the fuel used (for the same steam conditions, coal, nuclear and gas power plants all have the same theoretical efficiency)

Course outline

• Basic glossary

• Operating pressure
• Boiler efficiency
• Steaming hours
• Heating surface
• Generating surface
• Superheated steam

• Operating pressure
• the pressure at which the boiler is operated in service
• Boiler efficiency -the ratio between the thermal energy actually   and the thermal energy available  
• Steaming hours -the time during which the boiler generates steam
• Heating surface -the total surface of all parts exposed to combustion gases tubes, super heater, economizer
• Generating surface - a part of the surface in which water is heated and steam is generated

Tubes, drum

• Superheated steam
• saturated steam

• More heat at constant pressure
• Dry steam (to avoid damage to tubine blades)

• Main Elements of SPP
  • Furnace
  • Boiler
  • Super HEATER
  • Turbine
  • Condenser
  • Furnace
• chamber in which heat is produced – combustion of fuel & generation of hot gases
• burners – break oil into fine particles to ensure efficient combustion
• Boiler
  • steam generator – saturated and superheated steam
  • steam drum - a reservoir of water- steam at the top end of the water tubes, it stores the steam generated in the water tubes and acts as a separator for the steam -water mixture difference in densities
  • water circulation – natural or forced
• water tube boiler
• fire tube boiler
• Fire tube boiler
  • hot gases pass through the tubes, feed water surrounds them
• Water tube boiler
  • steam and water circulate through drums and small diameter tubes, gases of combustion pass around them
  • more commonly used, lighter, occupies less space and has increased efficiency higher pressure and temperature
• main boiler
  • Donkey (auxiliary) boiler
  • Low, intermediate, high pressure b.
  • Single-drum b., two-drum b., three-drum b.
  • Vertical b., horizontal b.
  • Single-flow b., double-flow

• Super heater

• consists of headers and super heater tubes
• converts saturated steam into dry steam

• Turbine

• Steam is admitted to the turbine
• heat energy is converted into mechanical energy – useful work
• high pressure turbine
• low pressure turbine

• Condenser
• heat exchanger

• Tubes sea water
• Steam water condensate
• Vacuum is created due to steam
• Condensate volume difference
• Vacuum is maintained by constant cool water circulation through the tubes

• Auxiliaries

• Condensate – Collecting Tank
• Main Condensate Pump

• Air Ejector

• Dee AERATING Fee ED Tank
• Make Up Tank - Emergency Feed Tank

• Feed Pump
• Fed Heater
• Economizer
• Main Condensate Pump

• condensate – collecting tank
• Main Condensate Pump
• to pump water from the hot well through the main air ejector to the deaerating feed tank

• Air Ejector
• no moving parts
• jet pump

• Bernoulli’s principle
• to remove air and gases from the condensate

• trading Feed Tank

• to remove the oxygen from the system
• to heat the condensate
• to be used as storage tank for heated feed water
• Form: cylindrical tank in three sections
• First section (the lowest) – storage space = beginning of the feed phase
• Middle section: atomizing valve assembly to release entrapped air from the water
• Upper section: preheater compartment

• Make Up Tank

• losses in cycle
• when the feed water level in the trading tank drops to a minimum, make-up feed water enters the system

• Feed pump

• pump that forces feed water into the boiler

• Feed heater

• preheats the feed water before it enters the boiler

• Economiser

• to improve the efficiency of the steam plant by using thermal energy, i.e. preheating the feed water before it passes into the boiler
• water is heated under pressure to remove dissolved air
• internal boiler corrosion

• Boiler Fuel Oil Supply System

• double-bottom tank
• transfer pump
• settling tank
• daily service tank
• fuel oil pressure pump

• strainer
• heater
• fine mesh

• burner (recirculating connection)
• Closed-feed system