Overall Performance Evaluation of Small Scale LNG Production Processes

Abstract

The liquefied natural gas (LNG) is considered a viable solution to replace oil-based engines (common in heavy-duty truck and naval industry) reducing the environmental impact in the transport sector. Since liquefaction plants represent energy intensive processes, the best configurations/operation assessment is of primary importance. In this paper, a novel general procedure for the thermodynamic design and optimization, engineering design and off-design evaluation for small-scale LNG production systems is presented. The procedure can be used for the complete design and performance evaluation of plug & play facilities at filling stations for vehicles/boats, with the contemporary benefits of reducing pollutant emission in the city/port area and operating as electrical storage, coupled with renewable generators. Furthermore, the procedure has been applied to a case study (ferry boat operating at the main canal in the port of Ravenna, Italy), evaluating the optimal size for the integrated wind plant by minimizing the electricity introduction into the grid. The obtained results show 78 kW as optimal wind size, allowing the LNG plant to operate 187 h/year in design and 4720 h/year in off-design conditions, with electricity surplus around 33 MWh/year. A prototype will be installed to reduce pollutant emissions and test this technology as a storage option for renewable sources.

Optimum Expanded Fraction for an Industrial, Collins-Based Nitrogen Liquefaction Cycle

“…Minor modifications [ 4 ] soon become better options when specific power consumption requirement (per unit mass of liquefied gas) and specific investment costs are considered even at medium scale. The Kapitza topology is a modification of the Claude by which the expander is connected in parallel to the expansion valve [ 5 ], simplifying the design.…”