Carbon Dioxide Liquefaction Process for Ship Transportation

Abstract

CO 2 liquefaction is an essential process for long-distance ship transportation. The conventional CO 2 liquefaction process employs either an external coolant or liquid expansion followed by multistage compression to obtain liquefied CO 2 at low pressure. However, these processes consume considerable amounts of energy, which presents an obstacle to commercialization. Thus, the CO 2 liquefaction process needs to be carefully researched and designed to reduce the operating energy. In this study, two alternative CO 2 liquefaction processes are proposed and evaluated. These alternative processes use multistage expansion and multistream heat exchangers to lower the input stream temperature for the compressor. In addition, the system is operated in a more efficient manner by operating the process with an optimized compression ratio. Evaluation of the economic feasibility was performed in this study for a complete assessment of the alternative processes. As a result, about 98.1 kWh/t of CO 2 was consumed for alternative process 2, which is only 91.8% of the total operating energy of existing CO 2 liquefaction processes, and the CO 2 liquefaction costs for alternative process 2 were reduced by 5.5%.

Optimization of the CO₂ Liquefaction Process - Performance Study with Varying Ambient Temperature

“…To begin with, a survey of previous studies was made to help identify the full range of possible process flow schemes available for the liquefaction process. Based on a review of the studies mentioned in the introduction [6,7,10,[13][14][15][16][17], three were selected as the basis for further work that covered all of the principle flow scheme alternatives: Alabdulkarem et al [16], Seo, et al [10], and Ø i, et al [17]. From these three studies, four 'base' flow schemes were then selected.…”

“…The IPCC special report on CCS [1], for example, identifies shipping as the lowest cost option for distances over liquefaction of CO2 in more detail. Although the majority of work is focused on either open cycle CO2 processes or closed cycle NH3 refrigeration processes [6,7,10,13,14], others have also studied more novel approaches such as the use of absorption refrigeration [15], cascade refrigeration [16], and the application of turbo expanders [17]. Some have also compared a broad range of schemes.…”

“…Hegerland [2] states that "To reduce investment costs of storage and ship tanks, it is required to operate as close to the triple point of 5.17 bara and -56.6 °C as practically feasible." Aspelund et al [6] and Lee, et al [14] looked at 6.5 bara transportation pressure based on the design of current commercial CO2 transportation by ship and also follow the assumption that the larger vessels used for CCS would operate at lower pressures. Decarre et al [7] compared liquefaction at 7 bara and 15 bara, finding that transportation at 15 bara offers both lowest cost and lowest energy consumption.…”

Parametric Optimization for Power De-Rate Reduction in the Integrated Coal-Fired Power Plant with Carbon Capture and Storage

“…For transporting CO 2 with ship, the CO 2 liquefaction process is considered. The simulation model for the liquefaction process was built based on the report of Lee et al 32 The liquefaction model proposed by Lee et al consumed a minimum compression energy of 98.1 kWh/t CO 2 without using an external refrigerant. Figure 4 shows the process flow diagram for the liquefaction model.…”

Optimization of the CO2 Liquefaction Process-Performance Study with Varying Ambient Temperature

“…Hegerland [6] states that "to reduce investment costs of storage and ship tanks, it is required to operate as close to the triple point of 5.17 bara and −56.6 • C as practically feasible." Aspelund et al [15] and Lee et al [16] looked at 6.5 bara transportation pressure based on the design of current commercial CO 2 transportation by ship and also follow the assumption that the larger vessels used for CCS would operate at lower pressures. Decarre et al [17] compared liquefaction at 7 bara and 15 bara, finding that transportation at 15 bara offers both lowest cost and lowest energy consumption.…”