Reheating of steam improved the thermal efficiency of the plant, net work output of turbine, reduction in blade erosion (or quality of steam improve). By regeneration thermal efficiency of the plant can be increased but it does not affect work output from turbine.
What are the disadvantages of reheat cycle?
1)
reheating requires more maintenance
2) the increase in thermal efficiency is not appreciable in comparison to the expenditure increased in reheating.
Which is more efficient reheat cycle or the regenerative cycle?
Analysis shows that
regenerative cycle
is more efficient compare to reheat cycle for a given set of operating conditions.
Is regenerative cycle alone useful?
It enables the reaction turbine to be placed over tailrace level. 9. Is regenerative cycle alone useful? Explanation:
Feedwater is preheated so as to decrease fuel consumption which increases efficiency
.
What is the function of steam reheating which is always valid?
Explanation: Reheat
increases work output
.
What is the practical limit of reheating?
What is the Practical Limit of Re-Heating? Theoretically if we increase the number of reheating stages then the number of expansion in the turbine can also be increased in order to get the more turbine output and thus higher cycle efficiency. But
practically more than two stages of reheat is not practical
.
What is ideal reheat regenerative Rankine cycle?
A steam power plant operates on an ideal reheat-regenerative Rankine cycle with
one open feedwater heater, one closed feedwater heater, and one reheater
. The fractions of stream extracted from turbines and the thermal efficiency of the cycle are to be determined.
What is the main purpose for adding reheat process to the cycle?
The reheat cycle
increases the turbine work and consequently the net work of the cycle
. This is accomplished not by changing the compressor work or the turbine inlet temperature but instead by dividing the turbine expansion into two or more parts with constant pressure heating before each expansion.
Why reheating of steam is used Examveda?
Solution(By Examveda Team)
The main purpose of reheating is
to avoid excess moisture and to increase the quality of steam at the end section of turbine
.
How effective is reheating and regenerating in improving working characteristics of the system?
A comparison study between the regular reheat regenerative cycle and the invented cycle is done. The results indicate that a gain in efficiency of
up to 2.5%
is obtained when applying invented cycle at the same conditions of pressure, temperatures, number of reheating stages, and feed water heaters.
What is the maximum possible tit turbine inlet temperature )?
What is the maximum possible TIT(Turbine Inlet Temperature)? Explanation: The maximum temperature is limited by metallurgical conditions. 4. A simple Brayton cycle uses Helium as the working fluid, has a maximum temperature of
1000 K
, and a pressure ratio of 4.
Does reheat increase efficiency?
Abstract. Reheating in a reheat regenerative steam power cycle
increases efficiency
by increasing the average temperature of heat reception, but also increases the irreversibility of feed water heaters by raising the temperature of the superheated steam used for the regenerative process.
What is the benefit of reheat?
This process is known as reheat. The main practical advantage of reheat (and of superheating) is the
decrease in moisture content in the turbine
because most of the heat addition in the cycle occurs in the vaporization part of the heat addition process. around the cycle, is increased.
What is the advantage of reheat cycle?
Advantages: The advantages of using a reheat cycle are
higher thermal efficiency, reduced feed water pump power, smaller condenser, smaller boiler, long life of the turbine and less handling of the fuel and firing requirement
.
What is the maximum temperature of regeneration in Brayton cycle?
The maximum temperature in the cycle (T3) is limited by metallurgical conditions because the turbine blades cannot sustain temperatures above
1300 K
. Higher temperatures (up to 1600 K can be obtained with ceramic turbine blades). The minimum temperature is set by the air temperature at the inlet to the engine.
When Brayton cycle efficiency is decreases with regeneration?
A most important point to notice is that contrary to a simple Brayton cycle, the thermal efficiency of a Brayton cycle with regeneration decreases with the
increase in pressure ratio
. Therefore, not all the combinations of pressure and temperature ratios induce an increase in thermal efficiency.
What is inter cooling in gas turbine powerplant?
Intercooling: It is
the stage of multi-compression in a gas turbine
. After the compression of gas in the first compressor, its pressure and temperature are increase this gas is passed through the intercooler where its temperature decrease. The intercooling process is done by passing an extra amount of water or air.
What are the advantages gained by reheating the steam in between stages?
The reheat cycle has been developed to take advantage of the
increased efficiency with higher pressures
, and yet avoid excessive moisture in the low pressure stages of the turbine. So with reheat the mean temperature of heat addition increases and so efficiency and work output.
What is ideal regenerative cycle?
In an ideal regenerative Rankine cycle,
steam enters the turbine at the boiler pressure and expands isentropically to an intermediate pressure
. Some steam is extracted at this state and routed to the feedwater heater, while the remaining steam continues to expand isentropically to the condenser pressure.
What are the benefits of reheat in Vapour power systems?
Reheating increases the efficiency by raising the mean temperature of the heat addition process, by increasing the steam temperature at the turbine inlet and also by increasing the efficiency of the expansion process in the steam turbine.
How do you increase the efficiency of a reheat cycle?
- Decreasing the condenser pressure. The effect of lowering the condenser pressure on the Rankine cycle efficiency is illustrated on a T-s diagram on the left. …
- Superheating the steam to a high temperature. …
- Increasing the boiler pressure.
What is the purpose of reheat cycle 1 marks ans?
The purpose of a reheating cycle is
to remove the moisture carried by the steam at the final stages of the expansion process
. In this variation, two turbines work in series.
What effect does the heating of feed water by steam bled from the turbine has on the Rankine cycle?
5. What effect does the heating of feedwater by steam ‘bled’ from the turbine has on the Rankine Cycle? Explanation: The heating of feedwater by steam ‘bled’ from the turbine, known as regeneration,
carnotinises the Rankine cycle
. 6.
Which combination of the following statements is correct the incorporation of regenerative feed heating?
Correct Option: B
Reheater always increases the dryness fractions of steam at condensor inlet
. Always increases the specific work output.
What do you understand by ideal regenerative cycle Why is it not possible in practice also give actual regenerative cycle?
The ideal regenerative cycle is not practically possible because
a heat exchanger cannot be installed inside the turbine as there are more chances for the erosion of the turbine blade
(last stage). The thermal efficiency of the ideal regenerative cycle is equal to that of the Carnot cycle.
