How does a open feedwater heater work?
An open feedwater heater is basically a mixing chamber, where the steam extracted from the turbine mixes with the water exiting the pump. At this state, some of the steam is extracted and sent to the feedwater heater, while the remaining steam in the turbine continues to expand to the condenser pressure (state 7).
Where is the closed feedwater heater located?
Closed feedwater heaters are typically shell and tube heat exchangers where the feedwater passes throughout the tubes and is heated by turbine extraction steam. These do not require separate pumps before and after the heater to boost the feedwater to the pressure of the extracted steam as with an open heater.
In which cycle part of steam is bled for feedwater heating?
The bled steam first enters the desuperheating zone enclosure and is cooled while raising the temperature of the feedwater leaving the heater to a level approaching or equal to the steam saturation temperature. The condensing zone is the largest heat transfer region within the heater shell.
Why at least one open heater is used?
Why at least one open heater is used? Explanation: The open heater works as a deaerator.
Are open or closed feedwater heaters more efficient?
Heat transfer in closed feedwater heaters is less effective since the two streams are not allowed to be in direct contact. Open feedwater heaters are simple and inexpensive and have good heat transfer characteristics. For each heater, however, a pump is required to handle the feedwater.
What is the efficiency of Rankine Cycle?
In modern nuclear power plants, which operate the Rankine cycle, the overall thermal efficiency is about one-third (33%), so 3000 MWth of thermal power from the fission reaction is needed to generate 1000 MWe of electrical power.
Why are feedwater heaters used?
Feedwater Heater Operation Feedwater heaters are used to heat feedwater before the water enters the boiler. The higher the feedwater temperature, the less fuel is required to produce the steam used to produce electricity in the steam turbine.
Which is the following is not an advantage of an open heater?
Which of the following is not an advantage of an open heater? Explanation: The disadvantage is the necessity of a pump at each heater to handle the large feedwater stream.
What are the two types of feedwater heaters?
There are actually two main types of feedwater heaters. If the steam mixes with the compressed water from the pump, it is an open feedwater heater. If the steam does not mix with the compressed water from the pump, it is a closed feedwater heater. T-S Diagram of an Ideal Regenerative Rankine Cycle with One Open Feedwater Heater
How is a feed water heater used in a power plant?
A feedwater heater is used in a conventional power plant to preheat boiler feed water. The source of heat is steam bled from the turbines, and the objective is to improve the thermodynamic efficiency of the cycle.
How does a closed feedwater heater work?
Closed feedwater heaters are typically shell and tube heat exchangers where the feedwater passes throughout the tubes and is heated by turbine extraction steam.
What happens to the steam in a feedwater heater?
However, the extracted steam (which is most likely almost fully condensed after heating the feedwater) must then be throttled to the condenser pressure, an isenthalpic process that results in some entropy gain with a slight penalty on overall cycle efficiency: