Analysis of CO₂ Emission and Economic Feasibility for a Heat‐Integrated Air Separation System

Abstract

Cryogenic air separation is a high‐energy consumption process and contributes significantly to greenhouse gas emissions. Reduction potentials of the CO2 emissions for both the full‐tower heat‐integrated air separation columns (F‐HIASC) and the top‐tower heat‐integrated air separation columns (T‐HIASC) are investigated. The optimization models of the minimum CO2 emissions are further proposed. The unit CO2 emissions of F‐HIASC and T‐HIASC can be decreased significantly compared to the conventional air separation columns (CASC). Furthermore, the capital cost and total annual cost are analyzed so as to evaluate properly the economic feasibility of HIASC. The results demonstrate that the total annual costs of F‐HIASC and T‐HIASC are much lower than that of CASC.

Optimization of Number of Stages for Energy Conservation and Economic Feasibility of the Heat-Integrated Air Separation Column

“…The feed in the form of a vapor–liquid mixture of nitrogen, oxygen, and argon is introduced at the bottom of the HPC. Theoretically, enough cold energy can be provided by energy recovery of the outgoing flows and air expansion if the whole system is adiabatic, and no extra refrigeration is required for the MHX. , Therefore, the process can be controlled realizing any feed thermal condition by adjusting the flow rate ratio of the feed air liquefied in the MHX to all feed air flows.…”

“…Chang et al , performed preliminary optimization designs on the withdrawal stage location and the corresponding flow rate. Subsequently, Cong et al optimized the heat-transfer capacity based on the analysis of CO 2 emission. Van der Ham et al studied the number of heat-integrated stages of the HIASC based on exergy analysis and entropy production.…”

“…The energy use of the feed compressor is mainly related to the compression ratio. For the intermediate compressor, the power duty is influenced not only by the compression ratio, but also by the vapor flow rate . The reflux and vaporization gradually accumulate along the columns, and the vapor flow rate can be increased with extended stages .…”

Comparison of Four Types of Vertical Radial‐Flow Adsorbers Based on Binary Adsorption of CO2 and H2O

“…Vertical radial-flow adsorbers are widely used in large-scale air separation systems to reduce the volume concentration of impurities in the air: H 2 O less than 3 mL m -3 , CO 2 less than 1 mL m -3 , hydrocarbons at a level of 10 -3 mL m -3 [1][2][3]. The energy consumption of the adsorber accounts for about 16 % of the total energy consumption of a large-scale air separation system, so performance improvement of the adsorber has great significance for large-scale air separation systems [3].…”

Temperature Inferential Control of Heat‐Integrated Distillation Column Based on Variable Sensitive Stage Temperature Set‐point

“…However, distillation has also resulted in severe environmental and energy‐related consequences because of its high energy consumption and low efficiency . Therefore, the improvement of distillation technology has become a widely‐discussed topic in recent years . Among the new technology, heat‐integrated distillation has attracted the attention of researchers since it has the potential for energy saving, possesses a high energy utilization rate, and can increase energy efficiency by more than 30 % than conventional distillation technology …”