The diaphragm steam seal is one of the essential components of the steam turbine in a power plant. It is used to manage the leakage of steam flowing through each stage, especially for the diaphragm steam seal of the high-pressure stage, the design is more complex and the requirements are more stringent.

The diaphragm steam seal is located between the stationary part (diaphragm) and the rotating part (rotor) of the steam turbine, and is used to limit the leakage of steam through the gap between the moving and static parts. The high-pressure 4th stage diaphragm steam seal is located inside the high-pressure cylinder, adjacent to the 4th stage blade group. Its main purpose is to reduce the leakage of steam from the high-pressure area to the low-pressure area, thereby improving the overall efficiency of the steam turbine.

The design of the diaphragm steam seal is based on the labyrinth seal principle. It consists of a series of staggered stationary teeth and rotating teeth to form a complex channel. When steam flows through these channels, the speed and pressure of the steam will change many times due to the tortuosity of the channel and the change of cross-sectional area, resulting in energy loss. This energy loss is manifested as a drop in steam pressure, which effectively reduces the amount of steam leakage.

The high-pressure 4th stage diaphragm steam seal is made of high-temperature and wear-resistant turbine alloy materials to adapt to the harsh working environment in the high-pressure cylinder. In terms of structural form, it adopts a labyrinth design, which achieves efficient sealing effect by precisely adjusting the gap between the moving and static parts. The size of the gap needs to be carefully calculated to balance the sealing performance and reduce the energy loss caused by friction.

For steam turbines, the diaphragm steam seal is an essential component to reduce steam leakage. Through the design of the labyrinth structure, the leakage of steam from the high-pressure area to the low-pressure area is effectively reduced, and the energy conversion efficiency of the steam turbine is improved. At the same time, the diaphragm steam seal helps to maintain the pressure difference between the various stages, ensuring that the steam can flow along the predetermined path, thereby optimizing the performance of the entire steam turbine.

By reducing steam leakage, the diaphragm steam seal can also prevent steam from entering the bearing box, avoiding contamination of the lubricating oil or overheating of the bearing. By reducing steam leakage, it also helps to reduce additional loads, thereby extending the service life of steam turbine components.

In order to ensure the good condition of the diaphragm steam seal, regular monitoring and maintenance are required. Monitoring indicators include but are not limited to temperature, vibration, pressure and flow. For example, by installing a temperature sensor, the temperature changes near the diaphragm steam seal can be monitored in real time, and abnormal conditions can be detected in time. Vibration analysis can capture changes in vibration modes caused by poor contact or wear between the diaphragm steam seal and the rotor. In addition, monitoring the steam pressure entering the bearing housing can help determine whether the sealing performance of the diaphragm steam seal is normal.

Yoyik offers various types of spare parts for power plant main turbine, generator and auxiliary equipment:
insulating tube Generator TQN-100-2
Water side gasket of condenser GH4145 Steam Turbine high pressure control valve
sealing ring 0200/0240/0220
Shaft end cover TU790111
movable joint dilation band DTPD60UI005
Stud M20 * 55 GB898B-88 35 Steam Turbine nozzle chamber
SEALRING SEC1,2,3,LPGLAND ASY6,7 34CrMo Steam Turbine CIV
Cylinder group connecting rod DTYD100UI002
BEARING BLOCK GH4145 Steam Turbine RSV
Shaft processing (turning sequence) Generator QFS-200-2
Manifold assembly (excitation) Generator qfsn2-660-2
OIL BAFFLE RING CATCH III, 0Cr17Ni4Cu4Nb Steam Turbine High pressure combined steam valve
exhaust fan 132.411.2Z
Balance drum nut DG600-240-03-19
SPECIAL NUT 40Cr2MoVA Steam Turbine LP casing
Generator sealing gasket Generator QFS-125-2
Core package clamping plate DG600-240
Sealing tile insulation gasket Generator QFQS-200-2
Flexible coupling DLC1100-8-00(A)
ACTIVE COVER 35CrMo Steam Turbine High pressure combined steam valve