Dynamic simulation of a hybrid once-through and natural circulation Heat Recovery Steam Generator (HRSG)

Energy ◽  
2022 ◽  
Vol 242 ◽  
pp. 122996
Author(s):  
Yaser Farahani ◽  
Ali Jafarian ◽  
Omid Mahdavi Keshavar
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):  
Nicolas J. Mertens ◽  
Falah Alobaid ◽  
Bernd Epple ◽  
Hyun-Gee Kim

The daily operation of combined-cycle power plants is increasingly characterized by frequent start-up and shutdown procedures. In addition to the basic requirement of high efficiency at design load, plant operators therefore acknowledge the relevance of enhanced flexibility in operation — in particular, fast start-ups — for plant competitiveness under changing market conditions. The load ramps during start-up procedure are typically limited by thermal stresses in the heat recovery steam generator (HRSG) due to thick-walled components in the high pressure circuit. Whereas conventional HRSG design is largely based on simple steady-state models, detailed modelling and dynamic simulation of the relevant systems are necessary in order to optimize HRSG design with respect to fast start-up capability. This study investigates the capability of a comprehensive process simulation model to accurately predict the dynamic response of a triple-pressure heat recovery steam generator with reheater from warm and hot initial conditions to the start-up procedure of a heavy-duty gas turbine. The commercial combined-cycle power plant (350 MWel) was modelled with the thermal-hydraulic code Apros. Development of the plant model is based on geometry data, system descriptions and heat transfer calculations established in the original HRSG design. The numerical model is validated with two independent sets of measurement data recorded at the real power plant, showing good agreement.


2013 ◽  
Vol 20 (2) ◽  
pp. 413-423 ◽  
Author(s):  
Xiao-ling Cao ◽  
Zheng-ren Pi ◽  
Shao-jian Jiang ◽  
Wei-hong Yang ◽  
B. Wlodzimerz

Author(s):  
Heimo Walter ◽  
Wladimir Linzer

The dynamic flow instability, namely density wave oscillation (DWO), was investigated theoretically. The analysis was done for different design configurations of the evaporator of a vertical type natural circulation heat recovery steam generator (HRSG) at low operation pressure under hot start-up conditions. The study was done for co-current and counter flow designs of the HRSG evaporator, different drum heights and different heat flux distributions over the heating surface of the evaporator. The investigations for the HRSG show that the heat flux distribution to the evaporator tubes has an important influence on the flow stability. The simulation results indicate that a lower amplitude of the mass flow oscillation of the working medium is given by a more uniform heat flux to the single tubes of the evaporator. This leads the two-phase flow system to a more stable condition. This study has also shown that changes in the drum height of the boiler have no significant influence on the oscillation amplitude of the DWO. The simulation results have shown that the counter flow design is much more stable under the investigated conditions compared to the co-current design.


2019 ◽  
Vol 66 (5) ◽  
pp. 331-339
Author(s):  
M. N. Maidanik ◽  
A. N. Tugov ◽  
N. I. Mishustin ◽  
A. E. Zelinskii

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