Turbine exit pressure vs condenser back pressure

The LP (Low-Pressure) turbine exit pressure, which is measured at the exhaust flange, may not be the same as the condenser backpressure.

Let’s break down these two concepts:

1. LP Turbine Exit Pressure: The LP turbine is the last stage of a steam turbine and is responsible for extracting energy from the steam to generate rotational motion. The LP turbine exhausts the steam at a certain pressure, which is typically measured at the exhaust flange. This pressure represents the pressure of the steam leaving the turbine and entering the condenser.
2. Condenser Backpressure: The condenser is a heat exchanger that cools down the exhaust steam from the turbine, condensing it into water. The backpressure of the condenser refers to the pressure at which the condensed water exits the condenser (pressure at hot well) and is typically measured at the outlet of the condenser (hot well).

While these two pressures are related and connected in a power plant’s steam cycle, they are not necessarily the same. The pressure drop between the LP turbine exit and the condenser backpressure is influenced by factors such as the steam flow rate, the design of the turbine, the efficiency of the condenser, and other system conditions.

In a well-designed and optimized system, the LP turbine exit pressure is usually higher than the condenser backpressure. This pressure difference allows for the proper flow of steam from the turbine to the condenser, facilitating the transfer of heat and the condensation process.

The LP turbine exit pressure and condenser backpressure are two important parameters that affect the efficiency of a steam turbine power plant. A lower LP turbine exit pressure and a lower condenser backpressure both lead to a higher efficiency, because this allows the turbine to extract more energy from the steam.

There are a number of factors that can affect the LP turbine exit pressure and condenser backpressure, including the temperature of the cooling water, the design of the turbine and condenser, and the amount of steam being generated.

The temperature of the cooling water is the most important factor, because it directly affects the amount of heat that can be removed from the steam. The design of the turbine and condenser also plays a role, because it determines how well the steam can be cooled and condensed. The amount of steam being generated also affects the LP turbine exit pressure and condenser backpressure, because a higher steam flow rate leads to a higher pressure drop in the turbine and condenser.

The LP turbine exit pressure and condenser backpressure are typically controlled by adjusting the amount of cooling water flow. A higher cooling water flow rate leads to a lower LP turbine exit pressure and condenser backpressure. However, there is a limit to how much cooling water can be used, because this can lead to problems such as corrosion and erosion.

The LP turbine exit pressure and condenser backpressure are important parameters that affect the efficiency of a steam turbine power plant. By controlling these parameters, it is possible to improve the efficiency of the plant and reduce the amount of fuel that is required.