Question

What are the effects of regenerative feedwater heating for the same turbine output?

1. It significantly increases the cycle efficiency and reduces the heat rate.

2. It increases the steam flow rate.

3. It increases the steam flow to the condenser.

4. If there is no change of boiler output, the turbine output drops.

Select the correct answer using the code given below:

1. 1, 2 and 3 only
2. 1, 2 and 4 only
3. 1, 3 and 4 only
4. 2, 3 and 4 only
5.

Answer 1

Correct Answer - Option 2 : 1, 2 and 4 only

Explanation:

Effect of regeneration:

(i) Efficiency increases & heat rate decreases, due to increase in mean temperature of heat addition.

(ii) For the same turbine output steam flow increases (a bigger boiler is required) due to bleeding of steam to heat the feed water.

(iii) Steam flow rate in the condenser is reduced at each stage of regeneration, steam is bleeding off because of this less amount of steam condense in the condenser.

(iv) If boiler size is fixed and the same amount of steam is produced then because of bleeding, less amount of steam available at turbine at each stage leads to decrease in turbine output.

Statement 4:

Due to same boiler output, turbine work is reduced and along with that heat, input decreases more significantly thereby increasing the efficiency.