Potassium Vapor Topping Cycle Gas-Fired Boiler Water Test

摘要

The potassium vapor topping cycle is a concept for increasing the efficiency of the Rankine vapor cycle by raising the peak temperature by employing a potassium vapor cycle with a turbine inlet temperature of 1500 to 1600 exp 0 F (815 to 870 exp 0 C) in which the waste heat rejected from the condensing potassium vapor is transferred to boiling water and steam in a conventional steam cycle. An efficiency of about 50% is calculated for this cycle with a natural circulation potassium boiler fired by gas or oil at 6 atm (0.6 MPa) pressure. A DOE program is underway at ORNL to build a full-scale potassium boiler tube bundle and burner module and test it with water and then potassium. The water tests and the results are discussed. The results of the argon distribution test indicate that the argon flow rate in all of the boiler tubes will be adequate to provide nucleation promotion for stable boiling of potassium. The heat load of individual boiler tubes was measured, and it was found that the outer bank of tubes has an averge heat load that is about 67% of the average for the inner bank, and the variation for individual tubes is about +-10% of the average for each bank. A peak temperature difference of 45 exp 0 F (25 exp 0 C) between the tube temperature of the inner and outer banks was measured during startup indicating that there should be no problems from thermal stresses. An exit steam quality of greater than 99.9% was found in the vapor separator test. (ERA citation 04:010138)