Relationship between a reducing valve and the stability of the main shaft seal of a water turbine

The stability of the main shaft seal of a water turbine has a direct impact on the overhaul period and safe operation of a unit.

Due to the structure of the main shaft seal, the cooling lubrication water provided by the technical water supply system of the unit should have a high reliability. Otherwise, the normal operation of the unit may be affected and even interruption of cooling water may be caused. As a result, a dry friction may take place, which may cause a high temperature to the main shaft seal and thus burn the unit.

For a hydropower station which adopts automatic flow for water supply, to enable its cooling water to meet the technical requirements required by the main shaft seal, it is required to install a stable and reliable reducing valve on the technical water supply system.

ZJY46H combined reducing valve is an excellent technical water supply device. It runs very stably on the water supply system and can automatically adjust the outlet pressure and flow according to the variation of the pipeline pressure and flow even in case of such complex conditions as starting and shutdown of the unit and load throw-off, so as to ensure that the downstream pressure and flow is within the set value. It features small noise and fluctuation, and provides a maintenance interval of 3-5 years and a service life of more than 10 years (Tianshengqiao No.2 Hydropower Station in Guizhou) in actual operation of the hydropower station. In addition, ZJY46H combined reducing valve provides two sets of feedback systems which work in the active/standby mode. This enables the reducing valve to work on the technical water supply system without any shutdown to overhaul.