Novel method for determining optimal heat-exchanger layout for heat recovery steam generators

Čehil, Mislav; Katulić, Stjepko; Schneider, Daniel Rolph

doi:10.1016/j.enconman.2017.03.033

Cited by 18 publications

(2 citation statements)

References 21 publications

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“…Large values of the pinch point reduce the heat transfer area needed due to the increase of the heat flux, and thus, the subcooled temperature difference increases too, Equation 3. The pinch point optimization is a typical methodology used to evaluate the performance in systems such as HRSGs and heat exchanger networks (HENs) [47,48]. In this work, this methodology is used but a different approach is proposed for the SG design of SPTPs.…”

Section: Results Of the Approach Point Optimizationmentioning

confidence: 99%

Thermo-economic optimization of molten salt steam generators

González-Gómez

Gómez-Hernández

Briongos

et al. 2017

Energy Conversion and Management

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This paper presents a methodology to guide the design of heat exchangers for a steam generator in a solar power tower plant. The low terminal temperature difference, the high fluid temperatures and the high heat duty, compared to other typical shell and tube heat exchanger applications, made the design of the steam generator for molten-salt solar power towers a challenge from the thermomechanical point of view. Both the heat transfer and the thermal stress problems are considered to size the preheater, evaporator, superheater and reheater according to the TEMA standards and ASME Pressure Vessel code. An integral cost analysis on the steam generator design effects on the power plant performance reveals an extremely low value for the optimum evaporator pinch point temperature difference. Furthermore, an optimization using genetic algorithms is performed for each heat exchanger, which leads to economical and feasible designs.A 110 MWe solar power tower plant is studied. Two configurations of the steam generator are proposed: with one or two trains of heat exchangers. The results show that the optimum pinch point temperature differences are very close to 2.6 ºC and 3 ºC for the steam generator with one and two trains, respectively.The proposed design of the steam generator consists of a U-shell type for superheater and reheater, a TEMA E shell forced circulation evaporator and a TEMA-F shell preheater. Also, the approach point temperature difference analysis is performed to avoid subcooled flow boiling in the preheater. An economic study to compare forced and natural circulation evaporator designs is carried out.

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Section: Results Of the Approach Point Optimizationmentioning

confidence: 99%

Thermo-economic optimization of molten salt steam generators

González-Gómez

Gómez-Hernández

Briongos

et al. 2017

Energy Conversion and Management

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“…Pan et al developed a new mixed integer linear programming model for a comprehensive retrofit of HENs and thus to improve heat recovery. Čehil et alpresented a novel approach to determine the optimal layout of a heat exchanger in the heat recovery steam generator (HRSG). Cassanello et al proposed a mixed integer nonlinear programming (MINLP) model for optimizing a multistream heat exchanger to maximize the heat recovery and minimize the heat exchanger surface.…”

Section: Introductionmentioning

confidence: 99%

Sustainable Retrofit Design of Natural Gas Power Plants for Low-Grade Energy Recovery

Tang

Chen

et al. 2019

Ind. Eng. Chem. Res.

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Large amounts of low-grade energy in natural gas power plants are not being efficiently recovered or used. They are often emitted directly to the environment. It is quite challenging to retrofit natural gas power plants for the integration of low-grade energy recovery and further optimize power generation, production and supply of hot and cold energy, and pipeline networks for cold energy distribution as a total site. In this study, we present a process superstructure for the sustainable retrofit of natural gas power plants to recover low-grade energy and deliver it to different users. The waste energy sources include cold energy from liquefied natural gas, pressure energy from pipeline natural gas streams, and lowgrade heat from low-pressure steam in power plants. A mixed integer nonlinear programming framework is formulated to optimize the process structure to minimize the total annual cost and maximize the exergy efficiency to obtain the best sustainable retrofit process for low-grade energy recovery. The optimization framework includes models of the existing gas turbines and boilers and the new pipeline network and refrigeration system. The mathematical framework is applied to a real industrial example, and the power consumption for cold energy production is significantly reduced by 32%. The ratio of different energy sources and the distance of cold energy distribution are investigated, and different optimization results are analyzed. Finally, exergy analysis is suggested to evaluate the sustainability of the retrofit. According to the results of the exergy analysis, the total exergy efficiency under the minimum total annual cost is increased by 6.172%.

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