Simulation and Energy Analysis of Pre-Cooling Loop in LNG Processes

Natural gas is one type of energy source that play an important part in supplying energy to the world and known to be the cleanest fossil fuel energy due to facts that it produce lower emission of sulfur and carbon dioxide. In the 1960, the first LNG plant has been built and the liquefaction process for natural gas has been introduced. During this process natural gas will be cooled down to -162°C at atmospheric pressure and the volume of liquid is reduced by 600 times of its gaseous volume. Liquefaction of natural gas has been the cornerstone of the LNG business since the transportation of natural gas to remote place becomes more economical viable. Despite the huge advantages of liquefaction process, the amount of energy consumed in producing LNG still considerably high. In the past decade, important amount of work has been focused on the design of LNG process. The aim of those work mainly focus on optimizing various developed LNG process.. This stage represents 40% of the work in the liquefaction process and it is important to reduced energy consumed in this stage of the liquefaction process. Due to the rapidly changing market conditions, escalating equipment costs, scarcity of resources for owners, contractors and suppliers, marginal projects will be put on the back burner but will continue to be evaluated for improved economics in the future. This paper proposed conceptual design strategies for improving total project design concepts for pre-cooling stage for Linde-Hampson cycle with a lesser energy consumption in the process. In this modification achieved 0.8% increment in productivity and specific power is reduced by 14%. It also gives lower LMTD reading while changes in heat exchanger effectiveness by 0.002. Besides that, this model study also uses less amount of refrigerant to achieve target natural gas outlet temperature.