Category: Steam Turbines

The steam turbine blades are subjected to high pressure and temperature. In the intermediate pressure stages, the steam is wet. Therefore, the material of blades should be able to withstand corrosion and erosion due to the presence of water particles. In addition to corrosion and erosion, blades are subjected to high centrifugal stresses. When the…

The exhaust steam from a steam power plant is often rejected to the atmosphere. When the heat of exhaust steam is used for heating of buildings, and heating required by many industrial processes, the functions of heating and power production can often be combined effectively. This combination is often called co-generation (Fig. 7.22). The process heater replaces…

In many cases, the power available from a back pressure turbine through which the whole of the heating steam flows is appreciably less than that required in the factory. In such cases, it would be possible to install a back pressure turbine to generate additional power. However, generally, the functions of both machines are combined…

There are several industries, such as paper making, textile, chemical, dyeing, sugar refining, and so on, in which there is a dual demand for power and steam for heating and process work. Producing steam separately for power and heating is wasteful. If the turbine is operated with normal exhaust pressure and the temperature of the…

Labyrinth seals are characterised as controlled clearance seals without rubbing contact with the moving parts and with some tolerable leakage. The fluid throttling is achieved in steps, using a series of small chambers, where a sudden irreversible acceleration with subsequent deceleration of the leaking fluid takes place. Every step down in this process of pressure…

The purpose of governing of steam turbines is to maintain the speed of a turbine sensibly constant, irrespective of the load. The various methods of governing are as follows:

The various losses in steam turbines and their causes are as follows:

The expansion of steam through a number of stages of turbine is shown in Fig. 7.13. A1B1 represents isentropic expansion in the first stage. The actual state of steam with frictional reheating is shown by point A2. Therefore, the actual heat drop in the first stage is A1C1. Similarly, the isentropic and actual heat drops in the succeeding stages are…

The steam passes to the fixed blades with velocity va1. Fixed blades also act as nozzles with pressure drop occurring, while steam passes through them so that there is gain in kinetic energy and steam leaves the fixed blades with velocity va2. The expansion of steam and the enthalpy drop occur in fixed and moving blades. The…