Simulation Study On Utilising Cold Energy Fuel To Liquefy Captured Co 2 On Lng-Fuelled Vessels

Depending on its mode of use, LNG possesses great value as a source of cold energy. The application of the cold energy of LNG to the petrochemical industry is explained hereunder.Facilities actually constructed and in operation which utilize the cold energy of LNG to separate the heavy components contained in the LNG are those at the Barcelona Terminal in Spain and the La Spezia Terminal in Italy.A method of using the cold energy of LNG for separation purposes and for the ethylene production unit itself, wherely ethane separated from LNG containing heavy components in used as feed for ethylene production, is described in the literature released by Air Products Ltd. in “LNG-1”.There is a process, in the patent stage, by which heavy components are separated from LNG containing such comporents and high-pressure methane gas is produced. This method does not require the use of the compressor for which a patent application has been lodged by Air Liquid.The methane is liquefied using the cold energy of LNG and vaporized after being pressurized with a pump.Similarly, Conch Methane Service has announced its patented method which utilizes the cold energy of LNG to separate refinery tail-gas into its individual components.A scrubbing method using LNG and propane chilled by means of liquefied nitrogen to remove trace quantities of impurities from hydrogen, is adopted.The use of the cold energy of LNG in an ethylene production plant, taking the case of an ethylene production rate of 300, 000 tons per year, is described briefly.In this case, 1, 380, 000 tons per year of LNG will be required if all necessary refrigeration is to be carried out by the sole use of LNG.Trial calculations were per formed on the basis of using LNG for the ethylene refrigeration around the demethanizer only. These calculations evaluate the cost of one kilogram of LNG at 1.59 yen.The use of the cold energy of LNG, especially in ethylene production units, will probably be realized with the establishment of stable supply and increased imports of LNG.

Aiming at the problems that the fuel releases a lot of cold energy and the refrigerated containers consume a lot of electricity on large LNG powered container ships, a set of cold energy cascade utilization scheme that mainly uses LNG cold energy for refrigerated containers is designed. The simulation software Aspen HYSYS is used to establish and simulate the process of the ship’s cold energy cascade utilization system under five different working conditions, and the main parameters of the key nodes are obtained, according to the established exergy efficiency model, the exergy efficiency of the main equipment and the whole system is solved. Under the five working conditions, the maximum exergy efficiency of the refrigerated container system before optimization is 24.54%, at this time, the exergy efficiency of the entire cold energy utilization system is 24.86%. With the goal of improving the exergy efficiency of the entire system, using a hierarchical optimization method, the key parameters affecting the exergy efficiency of each cold energy utilization module are analyzed and optimized respectively, and the optimal operating parameters of different cold energy utilization module were determined. So as to realize the optimization of the whole cold energy cascade utilization system. The results show that the exergy efficiency of the optimized LNG cold energy cascade utilization system for ships under five working conditions is improved, under the 65% working condition, the exergy efficiency of the optimized refrigerated container system is 27.69%, and the exergy efficiency of the whole cold energy utilization system is 28.04%, which are increased by 3.15% and 3.18% respectively. Which proves that the LNG cold energy cascade utilization system can realize the effective utilization of LNG cold energy.

Design and analysis of an efficient hydrogen liquefaction process based on helium reverse Brayton cycle integrating with steam methane reforming and liquefied natural gas cold energy utilization

In order to solve the problems of excess cold energy of the fuel and large power load required for refrigeration of refrigerated containers on LNG powered container ships, this study proposes a scheme to use the fuel cold energy of LNG powered container ships for refrigerated containers, the process simulation software Aspen HYSYS is used to simulate the cold energy utilization scheme, with the help of MATLAB, the multivariable optimization research on the cold energy utilization scheme of LNG powered container ship is carried out, taking the cold energy utilization rate of LNG cold energy scheme as the objective function, the LNG cold energy utilization scheme is optimized.

Thermodynamic and economic analysis of multi-generation system based on LNG-LAES integrating with air separation unit

Based on the principle of energy cascade utilization, this research uses 147000m3 LNG carrier as the research object. According to the principle of energy cascade utilization, LNG cold energy is applied to Rankine cycle power generation, ship desalination, ship low-temperature cold storage, ship high-temperature cold storage, ship air conditioning and nitrogen production, etc. Design a set of LNG cold energy comprehensive utilization system. Using Aspen HYSYS software for simulation, after analysis and calculation, the feasibility of the system design scheme was demonstrated. According to the route of the parent ship and the operating conditions of the cold energy utilization system, calculate the electricity and economic benefits saved by the LNG cold energy utilization system in each month. Through calculation, it can be known that 1.886×106 kW·h of electricity can be saved in one year, resulting in a benefit of more than 4 million yuan. The results show that the cold energy utilization system can bring good economic benefits and is worthy of promotion and application on ships.

The project of cold energy utilization for cold storage of Xingtan LNG satellite station is the first cold energy utilization demonstration project of LNG satellite station in China with (2–4) × 104 m3/day gasification rate of LNG and 10–15 tons/day supply of liquid ammonia in a temperature range of −25 to −38 °C. Its innovation lies in the point of adopting two ammonia refrigeration circulation systems to recover LNG cold energy for cold storage at the same time. Although this project had operated smoothly for more than 2 years after commissioning, there still existed some problems. Such as refrigerant frozen blocking problem and undersupply of cold energy which are caused by underperformed coordination between the two ammonia refrigeration circulation systems. According to the equipment running state and automatic control system data, this article presented optimized analyses of the whole process, including using a redesigned ammonia refrigerant flow channel and achieving dynamic balance of ammonia refrigeration to relieve the refrigerant frozen blocking phenomenon, improving production process and optimizing process parameters to ameliorate the condition of the cold supply shortage problem. Combined with the above research, many new methods were proposed which can effectively solve the above problems in the utilization of LNG cold energy so as to increase the LNG cold energy utilization ratio and enhance the safety and stability of project operation. In addition, it provides a valuable reference for design, development and construction of other analogous LNG cold energy utilization projects in China.

Cold storage is a chamber used for food preservation. The food is stored inside the cold storage at a specific temperature and relative humidity to slow down the deterioration process caused by pathogenic organisms. The type of food stored requires specific thermal conditions e.g 0-5 °C with RH of 80-90% for vegetables, 4-5 °C for milk processing, and -25 to -45 °C for quick freezing of fish. Cold energy from the LNG regasification process is a promising option for cold storage application. Normally, prior to supply to industrial users e.g power plants, the LNG is regasified by dissipating its cold energy to another working fluid of vapourizer e.g seawater in the Open Rack Vapourizer (ORV) or ambient air in the Ambient Air Vapourizer (AAV). Recovering this cold energy to cool the cold storage can significantly reduce the energy consumption in the cooling process. Simultaneously, it reduces greenhouse gas emissions. This study aims to investigate the potential of wasted LNG cold energy in a power plant’s regasification terminal, located in Aceh, as a source of energy to cool cold storage. The cooling load of cold storage under four different capacity namely 5, 10, 15, and 20 tons of fish is calculated and compared with the potential cold energy available. This study then concludes the cold storage capacity that meets the available LNG cold energy.

A new scheme for ammonia and fertilizer generation by coal direct chemical looping hydrogen process: Concept design, parameter optimization, and performance analysis

Development and modification of large-scale hydrogen liquefaction process empowered by LNG cold energy: A feasibility study

Proposal for a high efficiency LNG power-generation system utilizing waste heat from the combined cycle

Thermodynamic performance study of the SOFC-STIG distributed energy system fueled by LNG with CO2 recovery

In this paper, a cryogenic air separation process with LNG cold energy utilization is proposed to produce liquid nitrogen and high pressure pure oxygen gas economically. To reduce the electric energy consumption of air separation products, liquid nitrogen have been produced by condensing the separated pure nitrogen gas with LNG cold energy utilization, and the recycled nitrogen is served to transfer cold energy from LNG stream to cool off air stream in the proposed cryogenic air separation process. The specifications of streams and the major equipments of the air separation process are simulated with Aspen Plus software and the main parameters analysis are performed. The results show that the energy consumption of the proposed air separation process with LNG cold energy utilization decreased about 58.2% compared with a conventional cryogenic air separation process. The compressed pressure of recycled nitrogen has a big impact on the cost of air separation products and utilization efficiency of LNG cold energy. The LNG cold energy could be fully utilized when the recycled nitrogen has been compressed to above 6.5MPa.

For the hydrogen liquefaction, the large amount of energy is consumed, because precooling, liquefaction and ortho/para conversion heats should be eliminated. In this paper the basic design and thermal analysis are carried out to reduce the energy consumption by using LNG cold energy for precooling process in hydrogen liquefaction processes. The LNG cold energy utilization for hydrogen precooling enables not only to get energy saving for liquefaction, but to recover the wasted cold energy to sea water at the LNG terminal. The results show that the energy saving rate for liquefaction using LNG cold energy is almost 75% of current industrial hydrogen liquefaction plant. The demand flow-rate of LNG is only 15T/D for 1T/D hydrogen liquefaction.

Advancing greener LNG-fueled vessels: Compact simultaneous reduction system for CH4, NOX and CO2 emissions