Table of Contents
- 1 What is the effect of regeneration in Rankine Cycle?
- 2 What is the effect of regenerative feed water heating on the size capacity of boiler and condenser?
- 3 Why do we use regenerative feed heating in a steam power plant?
- 4 What are the advantages and disadvantages of regenerative cycle over simple Rankine cycle?
- 5 What is the efficiency of an ideal regenerative Rankine cycle?
- 6 What is the function of regenerator?
- 7 How do you increase the efficiency of a Rankine cycle?
- 8 What is the temperature of steam in a Rankine cycle?
What is the effect of regeneration in Rankine Cycle?
Regeneration increases the cycle heat input temperature by eliminating the addition of heat from the boiler/fuel source at the relatively low feedwater temperatures that would exist without regenerative feedwater heating.
What is the effect of regenerative feed water heating on the size capacity of boiler and condenser?
Regeneration improves the cycle efficiency by increasing the initial feed water temperature before the water, water enters the boiler and also helps in controlling the large the large flow rate of steam at the turbine exhaust.
Why does regeneration increases the thermal efficiency of the Rankine Cycle?
Thermal efficiency of the Rankine cycle increases as a result of regeneration since FWH raises the average temperature of the water before it enters the boiler. Many large power plants have as many as 8 FWH’s. In closed FWH, heat is transferred from the extracted steam to the feedwater without any mixing taking place.
What is effect of regeneration on efficiency?
It was found that increasing of regeneration effectiveness results in an increase in the output power of the cycle. It was also found that the cycle thermal efficiency increases with increasing of the regenerative effectiveness. The effect of ambient air temperature was also predicted.
Why do we use regenerative feed heating in a steam power plant?
It raises the cycle efficiency by reducing the external heat supplied by the boiler but at the expense of reducing the power output. Thus, without the available alternative use for the low-temperature boiler exhaust gases, the use of regenerative feed heating in large steam power plant would not be advantageous.
What are the advantages and disadvantages of regenerative cycle over simple Rankine cycle?
The thermal efficiency is improved because average temperature of heat addition to the cycle is increased. The Heating rate is reduced. The LP turbine blade height can be reduced because steam flow at lower stage is reduced. The steam condenser size can be reduced.
What is the effect of increasing superheat at constant inlet steam pressure & condenser pressure on cycle efficiency?
Clarification: An increase in inlet steam temperature, i.e. an increase in superheat at constant inlet steam pressure & condenser pressure gives a steady improvement in cycle efficiency & lowers the heat rate due to an increase in the mean temperature of heat addition. 6.
Why is the thermal efficiency greater with a regenerator than without for the same overall operating conditions?
The regenerator increases the temperature of the air entering the burner, thus reducing the fuel-to-air ratio and increasing the adiabatic thermal efficiency.
What is the efficiency of an ideal regenerative Rankine cycle?
The Effect on Cycle Efficiency
| Cycle Efficiencies | Unmodified Rankine Cycle | Rankine Cycle with Regeneration |
|---|---|---|
| Carnot efficiency | 52.6\% | 52.6\% |
| Thermal efficiency | 36.2\% | 38.4\% |
| \% Increase in Power Generation | 0\% | 6.1\% |
| mean temperature of heat addition | 226.7 C | 251.5 C |
What is the function of regenerator?
Regenerators are compact heat exchangers in which heat is alternately stored and removed using a heat storage matrix. During the heating period, the hot gas passes through the regenerator and transfers heat to the matrix.
What is regenerative feed heating?
Regenerative feed heating, where steam is drawn off the turbine between stages to preheat the feed water, is a well-established practice in steam power plant. From: Power Recovery from Low Grade Heat by Means of Screw Expanders (Second Edition), 2014.
When reheating is used in steam turbine then increased?
In case of two reheats, steam is super-heated twice at different constant temperatures. A high reheat pressure increases the the moisture content at turbine exhaust which results in scaling and it should be optimised. Thus the work produced is increased ,thereby efficiency increases.
How do you increase the efficiency of a Rankine cycle?
Generally, the efficiency of a Rankine cycle can be improved by increasing the pressure in the boiler. To avoid the increase of moisture in the steam coming out from the turbine, steam is expanded to an intermediate pressure and reheated in the boiler.
What is the temperature of steam in a Rankine cycle?
(b) T – s diagram. The steam in a reheat Rankine cycle leaves the boiler and enters the turbine at 60 bar and 390 °C. It leaves the condenser as a saturated liquid. The steam is expanded in the high-pressure turbine to a pressure of 13 bar and reheated in the boiler at 390 °C.
How does regeneration improve the thermal efficiency of a steam cycle?
One of the more common ways to improve the efficiency of a steam cycle is to use regeneration, a process where heat is taken from steam between turbine stages and used to heat water as it goes through pump stages. Using CyclePad, we will modify a Rankine cycle and examine the effects of regeneration on the cycle’s thermal efficiency.
Why is a Rankine turbine more efficient than a Carnot engine?
Since Carnot’s principle states that no engine can be more efficient than a reversible engine ( a Carnot heat engine) operating between the same high temperature and low temperature reservoirs, a steam turbine based on the Rankine cycle must have lower efficiency than the Carnot efficiency.