Comparative investigation of drum-type and once-through heat recovery steam generator during start-up

Mertens, Nicolas; Alobaid, Falah; Starkloff, Ralf; Epple, Bernd; Kim, Hyun-Gee

doi:10.1016/j.apenergy.2015.01.065

Cited by 52 publications

(10 citation statements)

References 19 publications

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“…A cold start-up procedure is studied to keep the thermal stress of the steam drum within the safety limits by means of the exhaust gas turbine bypass. Mertens et al [14] showed that the transient response of a once-trough-type HRSG is faster than a natural circulation drum-type using an HRSG software tool [15]. Rossi et al [16] modeled the start-up of a CCP showing that the intermediate pressure rotor stress is slightly higher than the highpressure rotor stress during a hot start-up.…”

Section: Introductionmentioning

confidence: 99%

Transient thermo-mechanical analysis of steam generators for solar tower plants

et al. 2018

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In solar power tower plants, fast start-ups and/or load changes are mandatory to increase the power plant dispatchability. The high temperatures of the working fluids and the partial-load operation will reduce the lifetime of the thick-walled components at the steam generator.Therefore, a proper heat exchanger design should consider the stress evolution during the transient operation of the plant. This work addresses, for the first time, a methodology to determine the dynamic behavior of all heat exchangers of a steam generator train. The methodology proposed here is a powerful tool for the design of solar power plants. The stress analysis model identifies the most important components of the steam generation train during transient operation. The methodology consists of the combination of analytical models to obtain the coupled response of the steam generation train from the following dynamic variables: temperature, pressure and stress.An example of this methodology is presented for two start-up initial conditions: the assumption of non-isothermal and isothermal temperature profiles of the heat exchangers. A steam generator train based on conventional shell and tube heat exchangers is analyzed. The analysis shows that the non-isothermal condition takes approximately 50 min to reach nominal conditions, whereas the isothermal condition takes approximately 110 min, requiring 600 tons and 716 tons of hot salt to perform the start-up procedure, respectively.

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Section: Introductionmentioning

confidence: 99%

Transient thermo-mechanical analysis of steam generators for solar tower plants

et al. 2018

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“…Different issues are addressed, such as the flows of gases and water, their geometry, and transient response. Mertens et al [6] investigate the dynamic behavior of a horizontal pass HRSG under the boundary condition of a gas turbine start-up. Simulation results with a commercial program are presented for start-up procedures from warm and hot initial conditions.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the efficiency of a heat recovery steam generator via computational simulations of off-design operation

Silva

Leiroz

Cruz

2020

J Braz. Soc. Mech. Sci. Eng.

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This work investigates the flow and heat transfer on the gas side of a heat recovery steam generator. During the operation of a power plant, off-design conditions that significantly impact the steam generator efficiency, caused by variations in the gas flow, corrosion and fouling of tube walls, may be encountered. In addition, passages around the heat exchanger modules develop along the equipment lifetime, allowing the bypass of flowing gas into zones of the boiler of low heat transfer effectiveness. These issues are here addressed via computational simulations, using a commercial software application for solving the mass, momentum, and energy conservation equations. The boiler geometry and the boundary conditions for the simulations are taken from a real, typical industrial heat recovery steam generator fed by gas turbines exhaust gases. Flow turbulence is modeled using the k-model, and heat exchanger modules are considered as porous media, through which the exhaust gases flow while supplying heat to the water. The water flow properties are specified from process data. Numerical results for thirteen realistic off-design conditions are compared to those for the boiler normal operation point. It is found that the cases considering deviation of gas to the trapdoors and lateral passages have the greatest impact on the boiler efficiency. Results indicate an efficiency drop from 86% for the base case to 48% for the case with gas deviations. In addition, a reduction in the gas flow or the plugging of the low-pressure economizer tubes may decrease the boiler efficiency by more than 10% points.

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“…Several researchers have investigated the critical stress points of combined cycle power plants (CCPPs) [6][7][8][9]. Dynamic models are usually developed to calculate the thermodynamic quantities (pressure, temperature, mass flow, etc).…”

Section: Introductionmentioning

confidence: 99%

Fatigue analysis of the steam generator of a parabolic trough solar power plant

González-Gómez

Gómez-Hernández

Briongos

et al. 2018

Energy

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This work proposes a methodology to perform the fatigue analysis of the steam generator of a parabolic trough power plant. The following methodology assumes cycling duty scenario (300 start-ups and shut downs per year). Two start-up operations of the steam generator are analyzed: evaporator temperature ramp and heat transfer fluid temperature ramp. Furthermore, a part load operation is studied.The results show that the most compromised parts of the steam generator are the reheater tubesheet for the TEMA CFU design, the steam drum-downcomer junction and the superheater nozzle. Besides, former reheater design (TEMA CFU) does not fulfil the 25-year lifetime condition. To overcome this problem, two alternative designs for the reheater are proposed: Ushell and two TEMA CFU in series. Finally, the lifetimes of TEMA NXU and kettle evaporator designs are compared. Our results show that TEMA NXU allows temperature ramps up to 9°C/min without putting the steam generator lifetime at risk, whereas kettle temperature ramps greater than 5ºC/min do not fulfill the designed lifetime of 25 years.Respect to the load changes, the evaporator drum is the most stressed element. A 50% load change produces a damage equivalent to 60% of the damage produced by a daily start-up/shutdown cycle.

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Comparative investigation of drum-type and once-through heat recovery steam generator during start-up

Cited by 52 publications

References 19 publications

Transient thermo-mechanical analysis of steam generators for solar tower plants

Transient thermo-mechanical analysis of steam generators for solar tower plants

Evaluation of the efficiency of a heat recovery steam generator via computational simulations of off-design operation

Fatigue analysis of the steam generator of a parabolic trough solar power plant

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