Using evolutionary search to optimise the energy consumption for natural gas liquefaction

Morin, Alexandre; Wahl, Per Eilif; Mølnvik, Mona J.

doi:10.1016/j.cherd.2011.03.002

Cited by 74 publications

(35 citation statements)

References 11 publications

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“…Hence, the focus has been on the PRICO LNG process, which is a relatively simple natural gas liquefaction process currently used in multiple plants world-wide (Hoffart and Price, 2014). Referring to Austbø et al (2014), the optimization of single cycle mixed refrigerant processes such as PRICO has previously been discussed in a number of works, and in a handful of these papers SQP techniques have been employed (Skaugen et al, 2010(Skaugen et al, , 2013Morin et al, 2011;Khan et al, 2012;Wahl et al, 2013). In our experience, the knowledge obtained in the study of relative simple processes like PRICO can also be applied for more complex processes.…”

Section: Introductionmentioning

confidence: 86%

Formulating the optimization problem when using sequential quadratic programming applied to a simple LNG process

Wahl

Løvseth

2015

Computers & Chemical Engineering

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a b s t r a c tSequential quadratic programming (SQP) may be very efficient compared with other techniques for the optimization of simple processes for the liquefaction of natural gas (LNG), and can be combined with process evaluation using commercial flowsheet simulators. However, the level of success is dependent on the formulation of the problem. In this work, effects of varying different aspects of the optimization problem formulation is investigated, such as variable selection, formulae for the estimation of derivatives, initial values, variable bounds, and formulation of constraints. Especially the formulation of the constraint for the temperature difference between the hot and cold composite curve is essential. The commonly used minimum temperature difference constraint should generally not be employed in gradient based optimization. Recommendations regarding optimization of simple LNG processes using SQP and flowsheet simulators are provided.

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Section: Introductionmentioning

confidence: 86%

Formulating the optimization problem when using sequential quadratic programming applied to a simple LNG process

Wahl

Løvseth

2015

Computers & Chemical Engineering

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“…For the same problems, convergence was much faster than other techniques reported in the literature [28,29,30]. To compare different optimization methods in a more rigorous way, a total of 16 different variations of optimization routines have been tested [31].…”

Section: Evaluation Of Lng Processesmentioning

confidence: 99%

“…To compare different optimization methods in a more rigorous way, a total of 16 different variations of optimization routines have been tested [31]. These include routines for both global and local optimization and include techniques like SQP, simulated annealing [32], and evolutionary search [30]. In general the local methods based on SQP are the most efficient ones, returning good solutions for simple and well formulated LNG problems for random initial conditions with only a fraction of the evaluations required by the global solvers.…”

Section: Evaluation Of Lng Processesmentioning

confidence: 99%

From Droplets to Process: Multilevel Research Approach to Reduce Emissions from LNG Processes

et al. 2015

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In the Enabling Low-Emission LNG Systems project, SINTEF Energy Research and NTNU have since 2009 been developing knowledge and tools with the aim to enable environmental safe, cost-effective, and energy efficient LNG processes. The project has employed a multilevel approach, where studies of fundamental phenomena, component modeling, and process optimization have been performed in parallel. Detailed models for two-phase flow in heat exchangers (HXs) have been developed, and falling films and droplet behavior relevant for LNG HXs have been studied experimentally. Further, the project work has generated robust and accurate HX models that can describe instabilities and include geometrical considerations. Finally, the project has improved the basis for optimization of LNG process through investigating of optimization tools and careful analysis and formulation of the optimization problem.

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“…In Aspelund et al (2010) the execution time was 4 or 12 hours typically with lower accuracy. In Morin et al (2011) the execution time for a similar problem with two compressors was around 22 hours and 40,000 flowsheet evaluations. In the work reported here, most runs completed in less than 2,000 evaluations.…”

Section: 2mentioning

confidence: 99%

“…Aspelund et al (2010) used tabu search combined with Nelder-Mead downhill simplex. Morin et al (2011) used evolutionary search for similar problems.…”

mentioning

confidence: 99%

Optimization of a simple LNG process using sequential quadratic programming

Wahl

Løvseth

Mølnvik

2013

Computers & Chemical Engineering

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The efficiency of using sequential quadratic programming (SQP) for the optimization of a PRICO process for the production of liquefied natural gas (LNG) is demonstrated. Most of the returned objective values have been better, and the execution times much lower, than in most previously published work on similar optimization cases. The optimization runs discussed in this paper require around 5 minutes of execution time.

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Using evolutionary search to optimise the energy consumption for natural gas liquefaction

Cited by 74 publications

References 11 publications

Formulating the optimization problem when using sequential quadratic programming applied to a simple LNG process

Formulating the optimization problem when using sequential quadratic programming applied to a simple LNG process

From Droplets to Process: Multilevel Research Approach to Reduce Emissions from LNG Processes

Optimization of a simple LNG process using sequential quadratic programming

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