Thermodynamic-Analysis-Based Energy Consumption Minimization for Natural Gas Liquefaction

Wang, Meiqian; Zhang, Jian; Xu, Qiang; Li, Kuyen

doi:10.1021/ie2006388

Cited by 81 publications

(28 citation statements)

References 9 publications

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“…Effluent after SR reactor is precooled by water at ambient temperature (25 °C) in the heat exchanger (HX) in which the heat is recovered to generate the steam fed in SR. In the cooler (C1), extra cooling water is used to cool the effluent down to 30 °C as reported by previous literature . Excessive water in the cooled syngas could be separated from the syngas product (PROD‐SR) in a flash drum (FL).…”

Section: Process Simulationmentioning

confidence: 99%

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Sustainability assessment of combined steam and dry reforming versus tri‐reforming of methane for syngas production

Chen

Gangadharan

Lou

2018

Asia-Pacific J Chem Eng

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Synthesis gas (syngas) is a versatile intermediate in the production of valuable chemicals and fuel, such as methanol, dimethyl ether, ethylene, propylene, and the Fischer–Tropsch fuel. Combining steam reforming and dry reforming (SR + DR) routes can produce syngas with a suitable H2:CO molar ratio (around 2:1) for Fischer–Tropsch synthesis. The newly proposed tri‐reforming (TR) route at experimental scale was a capable alternative to produce syngas in a single reformer with potential benefits such as energy savings and waste flue gas utilization. In this paper, sustainability assessment of SR + DR and TR routes adopting quantifiable indices in economic, environmental, and safety dimensions at industrial scale is performed based on process simulation models. Results show that TR route outperforms SR + DR route in all 3 dimensions. Sensitivity analysis of natural gas price fluctuation does not alter the conclusion. A sustainable root cause analysis is also applied on the SR + DR which identifies root causes affecting its sustainability with the aid of visualization tools such as Pareto chart and fish bone diagram.

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Section: Process Simulationmentioning

confidence: 99%

“…In the cooler (C1), extra cooling water is used to cool the effluent down to 30°C as reported by previous literature. 27,28 Excessive water in the cooled syngas could be separated from the syngas product (PROD-SR) in a flash drum (FL).…”

Section: Steam Reformingmentioning

confidence: 99%

Sustainability assessment of combined steam and dry reforming versus tri‐reforming of methane for syngas production

Chen

Gangadharan

Lou

2018

Asia-Pacific J Chem Eng

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“…Khan et al [16] decreased the overall compression energy requirement of the SMR process using Non-Linear Programming (NLP) and particle swarm paradigm. Wang et al [17] designed the C3MR process in Aspen Plus ® and presented an optimal design through Sequential Quadratic Programming (SQP). Hatcher et al [18], Lee et al [19], and Mortazavi et al [20] also modeled the C3MR process and subsequently optimized it via the Box method, Successive Reduced Quadratic Programming (SRQP), and hybrid optimization (i.e., Genetic Algorithm (GA) and SQP).…”

Section: Introductionmentioning

confidence: 99%

Single-Solution-Based Vortex Search Strategy for Optimal Design of Offshore and Onshore Natural Gas Liquefaction Processes

et al. 2020

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Propane-Precooled Mixed Refrigerant (C3MR) and Single Mixed Refrigerant (SMR) processes are considered as optimal choices for onshore and offshore natural gas liquefaction, respectively. However, from thermodynamics point of view, these processes are still far away from their maximum achievable energy efficiency due to nonoptimal execution of the design variables. Therefore, Liquefied Natural Gas (LNG) production is considered as one of the energy-intensive cryogenic industries. In this context, this study examines a single-solution-based Vortex Search (VS) approach to find the optimal design variables corresponding to minimal energy consumption for LNG processes, i.e., C3MR and SMR. The LNG processes are simulated using Aspen Hysys and then linked with VS algorithm, which is coded in MATLAB. The results indicated that the SMR process is a potential process for offshore sites that can liquefy natural gas with 16.1% less energy consumption compared with the published base case. Whereas, for onshore LNG production, the energy consumption for the C3MR process is reduced up to 27.8% when compared with the previously published base case. The optimal designs of the SMR and C3MR processes are also found via distinctive well-established optimization approaches (i.e., genetic algorithm and particle swarm optimization) and their performance is compared with that of the VS methodology. The authors believe this work will greatly help the process engineers overcome the challenges relating to the energy efficiency of LNG industry, as well as other mixed refrigerant-based cryogenic processes.

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“…Single mixed‐refrigerant processes have been subject to optimization in many studies, with varying values of the minimum temperature difference, such as 0.1 K, 1.2 K, 1.5 K, 2 K, 3 K, and 5 K . Similarly, the power consumption of propane‐precooled mixed‐refrigerant processes (C3MR) has been minimized requiring the minimum temperature difference to be larger than 2 K or 3 K. Alabdulkarem et al studied the influence of the minimum temperature difference on power consumption in a C3MR process by performing optimization with different values (0.01 K, 1 K, 3 K, and 5 K).…”

Section: Introductionmentioning

confidence: 99%

Impact of problem formulation on LNG process optimization

Austbø

Gundersen

2016

AIChE Journal

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The power consumption of a single mixed-refrigerant process (PRICO V R ) for natural gas liquefaction was minimized using four different constraint formulations to handle the trade-off between investment and operating costs. Aspen HYS-YS V R was used for process simulation, while a sequential quadratic programming algorithm (NLPQLP) was used for optimization. The results confirm that optimal utilization of the heat exchanger area is only obtained with a constraint based on a maximum heat exchanger conductance (UA). The minimum temperature difference constraint commonly used in process design gives a significant energy penalty as it is incapable of accounting for the distribution of driving forces with respect to temperature, the nonlinearity of the composite curves and the trade-off between driving forces and cooling load. The results also indicate that the maximum UA constraint leads to increased complexity of the optimization problem, and that the success rate of the optimization method used therefore is reduced. V C 2016 American Institute of Chemical Engineers AIChE J, 00: 000-000, 2016 Keywords: process optimization, heat transfer, driving forces, economic trade-off, liquefied natural gas IntroductionProcess design and operation is carried out with the prevailing objective of maximizing profit, or alternatively minimizing cost. Since detailed cost data seldom are available in an early design phase, a simplified approach is often taken. Both investment and operating costs are important for the overall economy of a plant, yet they are often in conflict. For many process units, improving operation comes at the expense of increased investment cost. Hence, to minimize the total cost of a process, the optimal trade-off between investment and operating costs must be found.For a heat-transfer process, both investment and operating costs are closely linked to the magnitude of the temperature driving forces. On one hand, the energy efficiency (and thereby the operating costs) is reduced when the driving forces are reduced. On the other hand, reduced driving forces lead to increased heat exchanger size (and thereby increased investment costs). To address this issue, a minimum temperature difference is commonly used as an economic trade-off parameter in heat exchanger network design. Jensen and Skogestad 1 found, however, that this approach gave suboptimal solutions when applied to design of processes for natural gas liquefaction, that is, subambient processes.Comparing different strategies for design of heat exchangers, Austbø and Gundersen 2 found that a design where the temperature difference in the heat exchanger is proportional to the temperature level, as suggested by Bejan, 3 Xu, 4 and Chang et al. 5 among others, gives the smallest irreversibilities associated with heat transfer. The potential savings in energy use, compared to a design with a uniform temperature difference throughout the heat-transfer process, were found to increase with decreasing temperature level and/or increasing temperature span. This sugg...

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Thermodynamic-Analysis-Based Energy Consumption Minimization for Natural Gas Liquefaction

Cited by 81 publications

References 9 publications

Sustainability assessment of combined steam and dry reforming versus tri‐reforming of methane for syngas production

Sustainability assessment of combined steam and dry reforming versus tri‐reforming of methane for syngas production

Single-Solution-Based Vortex Search Strategy for Optimal Design of Offshore and Onshore Natural Gas Liquefaction Processes

Impact of problem formulation on LNG process optimization

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