The optimization and thermodynamic and economic estimation analysis for CO2 compression-liquefaction process of CCUS system using LNG cold energy

Abstract Compression and liquefaction of carbon dioxide are important parts of the carbon capture, utilization, and storage (CCUS) process. A CCUS project with an actual workload of 1 million tons/year of China is simulated and analyzed in this paper. A new process scheme of compressed liquefaction of CO2 in the CCUS project by using liquid natural gas (LNG) cold energy through CO2 pipeline transportation is proposed to save energy and reduce consumption. The CO2 hydrate prediction models were compared. Based on the thermodynamic path of the CO2 compression liquefaction process, the energy consumption of four process models is compared. The relevant factors, which affect the economy of the new process are investigated, and the technical and economic model is optimized for the new technology scheme of CO2 pipeline. The total cost of the new process of economic is evaluated and the effective quantitative distances for energy saving are obtained. The results show that when the moisture content of CO2 is below 500ppmMol, the new technology will not cause hydrate blockage. The economic viability of the new process (Three stage compression with compressor + liquefaction by using cold energy + pump) is significantly affected by the distance between the LNG receiving station and thermal power plant, and the total cost will be reduced by 30%, 23% , and 8% at a distance of 25, 50 and 100 km, respectively. The distance between LNG receiving station and gas power plant is 125 km, the application of new technology can bring about energy saving and consumption reduction. Through the sensitivity analysis based on NPV and IRR of the new process, the results are economically feasible, and CO2 profit is the most sensitive factor.