Drainage Organization of Multi-Stage Steam-Jet Ejectors of Steam Turbines

The operational reliability of steam turbine condensing units largely depends on the reliability of the main ejectors. Ejector failure usually leads to turbine shutdown owing to a vacuum drop in the condenser. The main steam-jet ejectors typically include two or three stages, with intermediate coolers for the steam-air mixture. Most sudden failures of ejectors are associated with overfilling of these coolers with steam condensate, which creates high back pressure at the outlet of stage diffusers. This leads to a sharp increase in the pressure of the steam-air mixture at the ejector suction and consequently raises the steam pressure in the condenser. In this regard, the effective removal of steam condensate from coolers is crucial for maintaining overall ejector performance. There are two types of condensate removal schemes: cascade systems and those with separate outlets. The disadvantage of cascade schemes is that they add extra steam load to the lower stages owing to the incoming hot steam condensate from the upper stages. In addition, cascade circuits require the installation of cut-off valves (gates) for switching between ejectors, which poses a risk of air suction. Schemes with individual condensate drainage feature tall hydraulic seals, sometimes exceeding the elevation differences between the discharge point into the condenser and the lower level of the workshop floor. Implementing such a drainage system often involves drilling a shaft in the workshop floor and creating a drainage well. However, the disadvantage of this scheme is that it is not-repairable. Another notable disadvantage of existing drainage schemes for multi-stage steam-jet ejectors is the integration of drainage lines from different ejectors into a single collector. Organizing condensate removal schemes effectively is essential as it affects the operational reliability of the ejector maintenance system. The authors offer recommendations for optimizing condensate removal schemes from multi-stage steam-jet ejectors of steam turbines.