unit maintenance-1

Components of steam turbine and their functions

(HY-industry technical centre)

01. Condensing equipment is mainly composed of condenser, circulating water pump, steam extractor and condensate pump.

  • Establish and maintain a high vacuum at the steam turbine exhaust.

  • Condensate the exhaust steam of the turbine into water, which is then pumped by the condensation pump to the regenerative heater to become the feed water for the boiler. In addition, there is a certain vacuum deoxidation effect.

02. The role of condenser cooling water: condenses the exhaust steam into water, and absorbs the heat released by the condensation of the exhaust steam.

03. The function of the heater water-repellent device: reliably drain the water-repellent water in the heater, and prevent the steam from leaking out.

04. The function of the shaft seal heater: recover the shaft seal leakage steam, which is used to heat the condensed water to reduce the shaft seal leakage steam and heat loss, and improve the environmental conditions in the workshop.

05. The role of the low-pressure heater condensate bypass: When the heater fails or a certain heater is deactivated, the main condensate will not be interrupted.

06. The role of the heater installation exhaust valve: In order to prevent air from forming an air film on the surface of the copper pipe, which increases the thermal resistance and seriously affects the heat transfer effect of the heater, thereby reducing the heat exchange efficiency, the installation exhaust Valve.

07. The role of the water-side protection device in the high-pressure heater: When the high-pressure heater fails or the pipe is broken, it can quickly cut off the water supply to the heater tube bundle, and at the same time, ensure the water supply to the boiler.

08. The role of deaerator: used to remove oxygen and other gases in boiler feed water to ensure the quality of feed water. At the same time, it can heat the feed water and increase the feed water temperature.

09. The purpose of setting the water seal cylinder of the deaerator: to ensure that the deaerator does not overflow with water and flow into other equipment. Prevent deaerator overpressure.

10. The role of the deaerator water tank: to store the feed water and balance the difference between the water supplied by the feed pump to the boiler and the amount of condensate pumped water into the deaerator, so as to meet the needs of the boiler feed water.

11. Reboiler of deaerator: It is beneficial for heating the feed water in the water tank and maintaining the temperature of the standby water tank before the unit starts. It is beneficial to improve the deoxidation effect during normal operation.

12. The role of hydraulic check valve: to prevent the liquid in the pipeline from flowing backward.

13. The role of safety valve: a valve to ensure the safety of equipment.

14. The role of the pipe support and hanger: to fix the pipe and bear the weight of the pipe itself and the fluid in the pipe and the weight of the insulation material.

15. The role of feedwater pump: Continuously supply feedwater with sufficient pressure, flow rate and considerable temperature to the boiler.

16. The role of the circulating water pump: It is mainly used to provide cooling water to the condenser of the steam turbine, to condense the steam discharged into the condenser, and to provide cooling water to the oil cooler and generator cooler.

17. The role of the air pipe of the condensate pump: to discharge the accumulated air in the pump.

18. The role of temperature reduction and pressure reducer: as compensation for heating and peak heating (used in HY factory).

19. The role of temperature reduction and pressure reducing device:

  • In the external heating system, it is used to supplement the shortage of steam extraction by the turbine, and it can also be used as a backup steam source.

  • When the unit starts or stops or fails, it can play the role of regulation and protection.

  • It can be used as a steam source for low-pressure steam for factory use.

  • Exhaust steam used for recovery boiler ignition.

20. The role of steam turbine: a rotary prime mover that converts thermal energy into mechanical energy using water vapor with a certain temperature and pressure as a medium.

21. The role of the cylinder: The flow-through part of the turbine is separated from the atmosphere to form a closed steam room where the thermal energy of steam is converted into mechanical energy.

22. The role of steam seal: reduce the leakage of steam in the cylinder to the outside and prevent outside air from leaking into the cylinder.

23. The role of the exhaust cylinder: the steam discharged from the last stage of the turbine is poured into the condenser.

24. The function of the water injection device of the exhaust cylinder: In order to prevent the deformation of the cylinder caused by the exhaust temperature being too high, the consistency of the centerline of the static part of the steam turbine is destroyed, causing unit vibration or other accidents.

25. The role of the exhaust valve on the upper part of the low-pressure cylinder: In the case of an accident, if the pressure in the low-pressure cylinder exceeds the atmospheric pressure, it will automatically open the exhaust air to prevent the low-pressure cylinder, condenser, and low-pressure rotor from being damaged by overpressure .

26. The function of the impeller: It is used to install the blade and transmit the torque generated by the steam force on the cascade to the main shaft.

27. The role of the balance hole on the impeller: In order to reduce the steam pressure difference on both sides of the impeller, the excessive axial force generated by the rotor is reduced.

28. The role of the blade root: fasten the moving blade so that it will not be pulled out of the groove of the rim under the thrust of the steam flow and the centrifugal force of rotation.

29. The role of the sliding pin system

  • Ensure that the cylinder can expand freely, so as not to cause excessive stress to cause deformation.

  • Keep the final cause of the cylinder and rotor consistent, and avoid the center change caused by the expansion of the body, causing the unit to vibrate or friction between static and dynamic. (3) Make the axial and radial clearances of the stator and rotor meet the requirements.

30. Support bearings are also called radial bearings or main bearings: they support the weight of the rotor and the centrifugal force caused by the imbalance of the mass of the rotor, and determine the radial position of the rotor so that its center is consistent with the center of the cylinder.

31. The role of thrust bearing: bear the axial force of steam on the rotor, and determine the axial position of the rotor, so that the rotor and the stator part maintain a certain axial clearance.

32. The function of the cranking device: before the turbine starts to run and after the machine stops, the rotor is continuously rotated at a certain speed to ensure that the rotor is uniformly heated and cooled to prevent the large shaft from bending.

33. The function of the steam turbine regulation system: When the external load changes, the steam turbine power is adjusted in time to meet the needs of the user’s power consumption changes, while ensuring that the operating speed of the steam turbine generator set is within the normal allowable range.

34. The role of the synchronizer: change the speed of the steam turbine during single-unit operation, and change the power of the unit during parallel operation.

35. The role of the steam turbine regulation protection system: when the steam turbine regulation system fails or fails, it can act in time and stop quickly to avoid the expansion of accidents and equipment damage.

36. The role of the automatic main steam valve: After the protection device of the steam turbine is activated, the steam inlet of the steam turbine is quickly cut off and stopped.

37. The role of the emergency safety device: After the emergency safety device is activated, the secondary pulsating oil pressure of the regulating valve and the safety oil pressure of the main valve are discharged, so that the main valve and the speed regulating valve are quickly closed.

38. Additional overspeed protection effect: If the emergency safety device fails, the unit’s speed will rise to 113% -114% of the rated speed, assist the overspeed protection action, make the emergency safety device act and stop.

39. The role of axial displacement protection: When the axial displacement of the steam turbine reaches a certain value, the protection acts and stops.

40. The function of low oil pressure protection: The low oil pressure protection device will issue alarm signals in sequence according to the degree of oil pressure reduction, link the auxiliary oil pump, stop and crank.

41. The role of the low vacuum protection device: When the vacuum is lower than the normal value, the low vacuum protection device sends an alarm signal.

42. The role of the main oil tank: In addition to storing oil in the oil system, it also plays a role of separating water, sediment and bubbles in the oil.

43. The role of oil cooler: cooling oil for cooling the turbine generator set bearings.

44. Fuel injector principle and function: When the high-pressure oil is sprayed through the oil nozzle at a high speed, a vacuum is formed at the nozzle outlet, and the free-jet entrainment is used to bring the oil in the fuel tank through the filter to the diffuser to reduce the pressure and increase Exhausted at a certain pressure. Improve the reliability of the main oil pump.

45. The role of air cooler: to ensure the normal operation of the generator within the allowed temperature.

46. ​​The role of the steam turbine nozzle: convert the thermal energy of steam into kinetic energy, that is, steam expansion, pressure reduction, and speed increase, which is ejected in a certain direction to push the moving blades to do work.

47. The role of the condenser to set up a hot water well: gathering condensed water is conducive to the normal operation of the condensing pump.

48. The role of the steam extractor: continuously extract the air and other non-condensable gases in the condenser to maintain the vacuum of the condenser.

49. The role of the water jet pump: to provide a certain pressure to the water jet steamer to supply water.

50. The role of the pressure regulator in the steam turbine: adjust the steam supply pressure to a certain range.

51. The role of the heater: use the steam that has done some work in the steam turbine to pump the heater to heat the feed water, increase the temperature of the feed water, reduce the amount of steam discharged from the steam turbine to the condenser, reduce the loss of cold source, and improve the heat power System cycle efficiency.

52. Equalizing box function: adjust the steam supply pressure and recover the remaining steam. 53. High-pressure oil motor function: Control the opening of the speed-regulating steam valve to control the steam intake of the turbine.

54. Medium pressure oil motive effect: Control the opening of the rotating baffle to control the pressure and flow of external steam supply.

55. The role of the bypass system:

  • Ensure the minimum load evaporation of the boiler

  • Protect the reheater

  • Accelerate startup speed and improve startup conditions

  • Acts as a boiler safety valve

  • Recover working fluid and part of heat to reduce exhaust noise

  • Guarantee steam quality.

56. The role of condensing equipment: increase the ideal enthalpy drop of steam in the steam turbine and improve the cycle thermal efficiency of the unit. The exhaust steam is condensed into water to recover the working fluid and sent back to the boiler as feed water.

57. The role of high-pressure heaters: use the steam in the steam turbine to do part of the work to heat the boiler feed water and increase the feed water temperature to reduce the thermal load on the boiler and increase the thermal economic benefits of the thermal power plant.

58. The role of the low-pressure heater: use the steam or steam leak from the steam turbine to do some work to heat the main condensate and recover heat and working fluid.

59. The role of the check valve: restrict the flow direction of the fluid and prevent the liquid from flowing in the reverse direction.

60. Pressure reducing valve: keep the steam supply pressure within the specified range.

61. Jet pool: Provide sufficient water for the jet pump.

62. Cooling tower: cooling circulating water.

63. The role of water distribution tanks and splash dishes in the cooling tower: make the water splash continuously to increase the contact area with the air and improve the cooling effect.

64. Speed-regulating steam valve: used for rushing and controlling the steam intake.

65. Bypass gate for electric main gate valve: used for secondary heating pipe and starting turbine.

66. Condensate pump: send condensate to deaerator in time.

67. Air valve of the condensate pump: Ensure that the pressure at the inlet of the condensate pump is equal to the pressure in the condenser, to prevent gas from entering the inlet and falling water.

68. Softening the water gate: Before starting the condensing pump, inject softened water into the condenser to maintain a proper position of the water level of the hot water well.

69. Recirculation door: to maintain the water level of the condenser hot water well.

70. Injection valve: lower the temperature of the rear cylinder.

71. Oil filter: clean up the impurities in the oil in time to ensure the safe operation of the unit.

72. Feedwater pump recirculation pipe: To prevent the water in the feedwater pump from being vaporized when the feedwater pump is empty or under load.

73. Set the steam and water balance pipes on the steam side and water test of the deaerator: keep the pressure and water level of the deaerators running in parallel to be the same.

74. Turbine Turbine Oil:

  • Lubricate the bearings and other rotating parts of the steam turbine generator and take away the heat generated by friction, as well as the heat transmitted to the steam turbine by the high temperature steam.

  • Steam turbine speed control system and various hydraulic control valve transmission tools.

75. Oil tank exhaust hood: exhaust gas and water vapor from the oil and establish negative pressure.

76. Synchronizer lower limit rich travel: In order to make the speed regulation valve close quickly when the turbine suddenly loses load at low cycle rate, to ensure the safety of the unit.

77. Synchronizer upper limit: In order to prevent the opening of the synchronizer from exceeding the normal value due to changes in steam parameters during operation.

78. Synchronizer lower limit: to ensure that the unit can be juxtaposed or disjointed reliably when the electrical cycle rate is reduced.

79. Up and down rich travel of oil motive: ensure that the governor valve is fully open or fully closed.

80. Boiler sewage expansion container: The sewage in the boiler is discharged into the expansion container, which increases the volume and reduces the pressure, vaporizes part of the sewage, thereby recovering part of the water and heat.

81. High and low pressure oil connection valve in oil system: When starting the unit, start the low pressure oil pump through this door first, and slowly fill the whole system with oil to catch air, so as not to cause pipeline vibration or the speed control system to jump.

82. Centrifugal oil pump oil supply system: ⑴ Supply oil to the bearings of the unit, lubricate and cool the bearings. ⑵ Supply stable and sufficient pressure oil for the speed regulation system and protection device, and ⑶ supply lubricating oil for gears and other transmission mechanisms.

83. AC and DC lubricating oil pumps: When the turbine fails and the main oil pump cannot supply lubrication oil, supply oil to the lubrication system and crank oil.

84. Overpressure valve (oil spill valve) in lubricating oil system: adjust the lubricating oil pressure.

85. High and low pressure hydrophobic expansion tank: the recovery cylinder and the steam extraction pipeline are hydrophobic, so that the temperature difference between the upper and lower cylinders is reduced.

86. Accident fuel release valve: used for oil system fire to release oil in the fuel tank and reduce loss.

87. Drain gate in the condensate water: discharge the unqualified condensate water to ensure that the qualified water enters the boiler.

88. Vacuum destruction door: used for emergency shutdown and rapid shutdown at critical speeds and to prevent damage caused by unit resonance.

89. Extraction check valve: Controls the hydraulic check valve on the extraction pipe. Purpose: Cut off the steam extraction to prevent steam and liquid in the pipeline from causing water shock to damage the turbine.

90. Magnetic cut-off throttle: It consists of an electromagnet and an electromagnetically controlled throttle part. When the electromagnet is energized, the throttle piston moves down, the security oil is leaked, and the accidental oil is shut down.

91. The function of the partition cover: it is used to install and fix the partition.

92. The role of the turbine oil system:

  • Supply oil to the bearings of the unit in order to lubricate and cool the bearings.

  • Supply stable and sufficient pressure oil to the regulating system and protection device.

  • Supply lubrication oil for each transmission mechanism.

93. High pressure overpressure valve (pressure reducing valve): When the unit lubricating oil is discharged from the main oil pump through the pressure reducing valve to supply oil, the oil pressure entering the lubricating oil system is adjusted through the pressure reducing valve.

94. Low pressure overpressure valve (safety door): When the pressure of the lubricating oil is too high, the overpressure valve operates to discharge a part of the oil to the fuel tank to ensure a constant lubricating oil pressure.

95. The role of the rotor: withstand the rotating force of steam on all working blades, and drive the generator rotor, main oil pump and governor to rotate

96. The role of the main oil pump: it is the power of the oil system, which continuously sends oil to the lubricating oil and regulates the oil system during normal operation.

97. Steam oil pump or high-pressure electric oil pump (speed-regulating oil pump) role: used to supply power oil and lubricating oil when the main oil pump does not work normally during the startup or shutdown of the turbine. It is also used for the static characteristic test of the adjustment system after shutdown.

98. Role of AC oil pump and DC oil pump: Generally, it is used to supply lubricating oil for steam turbine in the condition of steam turbine cranking or accident.

99. Oil filter function: installed on the lubricating oil and speed regulating oil pipelines, mainly to prevent debris in the oil from entering the bearings and regulating the oil system.

100. The role of each component of the steam turbine regulating system:

  • Rotating speed sensing mechanism: It senses the speed change of the steam turbine and converts it into a signal of displacement change or oil pressure change and sends it to the transmission amplification mechanism.

  • Transmission amplifying mechanism: Amplifies the output signal of the speed and sensing mechanism and transmits it to the actuator.

  • Actuating mechanism: It is usually composed of two parts: adjusting valve and transmission mechanism. According to the output signal of the transmission amplifying mechanism, the steam input of the turbine is changed.

  • Feedback device: In order to maintain the stability of the adjustment, the adjustment system must be provided with a feedback device to make the output signal of a mechanism reversely adjust the input signal, so as to stabilize the adjustment process.

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