scholarly journals Heat recovery from Combined Cycle Power Plants for Heat Pumps

2019 ◽  
Vol 113 ◽  
pp. 01011
Author(s):  
Alberto Vannoni ◽  
Alessandro Sorce ◽  
Sven Bosser ◽  
Torsten Buddenberg

Fossil fuel power plants, as combined cycle plants (CCGT), will increasingly have to shift their role from providing base-load power to providing fluctuating back-up power to control and stabilize the grid, but they also have to be able to run at the highest possible efficiency. Combined Heat and Power generation could be a smart solution to overcome the flexibility required to a modern power plant, this work investigates different layout possibilities allowing to increase the overall efficiency through the heat recover from the hot flue gasses after the heat recovery steam generator (HRSG) of a CCGT. The flue gas (FG) cooling aims to recover not only the sensible heat but also the latent heat by condensing the water content. One possible solution couples a heat pump to the flue gas condenser in order to increase the temperature at which the recovered heat is supplied, moreover the evaluated layout has to comply with the requirement of a minimum temperature before entering the stack.

Author(s):  
Akber Pasha

In recent years the combined cycle has become a very attractive power plant arrangement because of its high cycle efficiency, short order-to-on-line time and flexibility in the sizing when compared to conventional steam power plants. However, optimization of the cycle and selection of combined cycle equipment has become more complex because the three major components, Gas Turbine, Heat Recovery Steam Generator and Steam Turbine, are often designed and built by different manufacturers. Heat Recovery Steam Generators are classified into two major categories — 1) Natural Circulation and 2) Forced Circulation. Both circulation designs have certain advantages, disadvantages and limitations. This paper analyzes various factors including; availability, start-up, gas turbine exhaust conditions, reliability, space requirements, etc., which are affected by the type of circulation and which in turn affect the design, price and performance of the Heat Recovery Steam Generator. Modern trends around the world are discussed and conclusions are drawn as to the best type of circulation for a Heat Recovery Steam Generator for combined cycle application.


Author(s):  
H. H. Finckh ◽  
H. Pfost

Unfired combined cycles achieve superior efficiencies at low emission levels. The potential and efficiency limits are investigated and the possibilities for enhancing efficiency are described. It is demonstrated that limited supplementary firing of the heat recovery steam generator can be an interesting alternative and that this allows efficiency and plant size to be increased. The effects of supplementary firing on NOx emissions are also shown.


Author(s):  
P. J. Dechamps

Natural gas fired combined cycle power plants now take a substantial share of the power generation market, mainly because they can be delivering power with a remarkable efficiency shortly after the decision to install is taken, and because they are a relatively low capital cost option. The power generation markets becoming more and more competitive in terms of the cost of electricity, the trend is to go for high performance equipments, notably as far as the gas turbine and the heat recovery steam generator are concerned. The heat recovery steam generator is the essential link in the combined cycle plant, and should be optimized with respect to the cost of electricity. This asks for a techno-economic optimization with an objective function which comprises both the plant efficiency and the initial investment. This paper applies on an example the incremental cost method, which allows to optimize parameters like the pinch points and the superheat temperatures. The influence of the plant load duty on this optimization is emphasized. This is essential, because the load factor will not usually remain constant during the plant life-time. The example which is presented shows the influence of the load factor, which is important, as the plant goes down in merit order with time, following the introduction of more modern, more efficient power plants on the same grid.


1997 ◽  
Vol 119 (4) ◽  
pp. 250-256 ◽  
Author(s):  
H. Jin ◽  
M. Ishida ◽  
M. Kobayashi ◽  
M. Nunokawa

Two operating advanced power plants, a supercritical steam plant and a gas-steam turbine combined cycle, have been analyzed using a methodology of graphical exergy analysis (EUDs). The comparison of two plants, which may provide the detailed information on internal phenomena, points out several inefficient segments in the combined cycle plant: higher exergy loss caused by mixing in the combustor, higher exergy waste from the heat recovery steam generator, and higher exergy loss by inefficiency in the power section, especially in the steam turbine. On the basis of these fundamental features of each plant, we recommend several schemes for improving the thermal efficiency of current advanced power plants.


Author(s):  
G. Negri di Montenegro ◽  
A. Peretto ◽  
E. Mantino

In the present paper, a thermoeconomic analysis of combined cycles derived from existing steam power plants is performed. The gas turbine employed is a reheat gas turbine. The increase of the two combustor outlet temperatures was also investigated. The study reveals that the transformation of old conventional fossil fuel power plants in combined cycle power plants with reheat gas turbine supplies a cost per kWh lower than that of a new combined cycle power plant, also equipped with reheat gas turbine. This occurs for all the repowered plants analyzed. Moreover, the solution of increasing the two combustor outlet temperatures resulted a strategy to pursue, leading, in particular, to a lower cost per kWh, Pay Back Period and to a greater Internal Rate of Return.


1992 ◽  
Vol 114 (4) ◽  
pp. 653-659 ◽  
Author(s):  
H. H. Finckh ◽  
H. Pfost

Unfired combined cycles achieve superior efficiencies at low emission levels. The potential and efficiency limits are investigated and the possibilities for enhancing efficiency are described. It is demonstrated that limited supplementary firing of the heat recovery steam generator can be an interesting alternative and that this allows efficiency and plant size to be increased. The effects of supplementary firing on NOx emissions are also shown.


2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Stefano Giuliano ◽  
Reiner Buck ◽  
Santiago Eguiguren

Selected solar-hybrid power plants for operation in base-load as well as midload were analyzed regarding supply security (dispatchable power due to hybridization with fossil fuel) and low CO2 emissions (due to integration of thermal energy storage). The power plants were modeled with different sizes of solar fields and different storage capacities and analyzed on an annual basis. The results were compared to each other and to a conventional fossil-fired combined cycle in terms of technical, economical, and ecological figures. The results of this study show that in comparison to a conventional fossil-fired combined cycle, the potential to reduce the CO2 emissions is high for solar-thermal power plants operated in base-load, especially with large solar fields and high storage capacities. However, for dispatchable power generation and supply security it is obvious that in any case a certain amount of additional fossil fuel is required. No analyzed solar-hybrid power plant shows at the same time advantages in terms of low CO2 emissions and low levelized electricity cost (LEC). While power plants with solar-hybrid combined cycle (SHCC®, Particle-Tower) show interesting LEC, the power plants with steam turbine (Salt-Tower, Parabolic Trough, CO2-Tower) have low CO2 emissions.


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