An Improved CO2 Separation and Purification System Based on Cryogenic Separation and Distillation Theory

Abstract

Abstract:In this study, an improved CO 2 separation and purification system is proposed based on in-depth analyses of cryogenic separation and distillation theory as well as the phase transition characteristics of gas mixtures containing CO 2 . Multi-stage compression, refrigeration, and separation are adopted to separate the majority of the CO 2 from the gas mixture with relatively low energy penalty and high purity. Subsequently, the separated crude liquid CO 2 is distilled under high pressure and near ambient temperature conditions so that low energy penalty purification is achieved. Simulation results indicate that the specific energy consumption for CO 2 capture is only 0.425 MJ/kgCO 2 with 99.9% CO 2 purity for the product. Techno-economic analysis shows that the total plant investment is relatively low. Given its technical maturity and great potential in large-scale production, compared to conventional MEA and Selexol TM absorption methods, the cost of CO 2 capture of the proposed system is reduced by 57.2% and 45.9%, respectively. The result of this study can serve as a novel approach to recovering CO 2 from high CO 2 concentration gas mixtures.

Investigating the Plasma-Assisted and Thermal Catalytic Dry Methane Reforming for Syngas Production: Process Design, Simulation and Evaluation

“…The cryogenic separation process attains high separation efficiency and compression and refrigeration systems are well-established at large scale. Nevertheless, extremely low temperature and high compression rates increase substantially the operation cost [47] and many efforts are currently devoted to process optimization and energy requirement reduction [48,49].…”

“…Based on the simulation results, ~5.3 kWh/kmolsyngas cold utility, 3.1 kWh/kmolsyngas hot utility and 7.9 kWh/kmolsyngas electrical power are required for syngas purification. The capital investment of the TM Cryogenic separation is not only used in oil and gas industry for light hydrocarbons separation [56,57], but also for synthetic natural gas purification [47,58]. Although cryogenic separation requires no chemical agents, the extreme operating conditions require high energy consumption, which is a major drawback.…”

“…The capital investment of the CO 2 liquefaction process is lower than the MEA absorption process and similar to Selexol TM absorption process [55]. Xu et al [47] have also compared the total capital investments of a CO 2 liquefaction process over the Selexol TM process and concluded that the first is about 40% less expensive than the second one. Thus, the capital investment of the CO 2 liquefaction process is about 4 k$/(kmol syngas h −1 ) including the compression section and the refrigeration system needed to achieve the required operating temperatures.…”

Techno-economic modeling and optimization of solar-driven high-temperature electrolysis systems

“…The cost of separating CO 2 from the produced gases was assumed to be $10.28/tCO 2 based on a multi-stage compression, refrigeration and cryogenic separation processes (Xu et al, 2014). These costs were added to C feed (see section 3.6).…”

“…The reactant mixture is fed to the electrolyzer's cathode, where steam/CO 2 is split into H 2 /CO with conversion extent, W ce . The high temperature exhaust (a mixture of H 2 , CO, H 2 O, and CO 2 ) is recovered in heat exchanger 1, condensed in the condenser (splitting liquid water from the gases), and separated into pure CO 2 (piped into mixer 2 for recycling) and H 2 /CO streams by a cryogenic separation process (Xu et al, 2014). The H 2 /CO stream is further separated into two parts: (i) a small fraction of hydrogen/CO (5%/5%) is injected into mixer 1 to prevent oxidation at the cathode electrode and to maintain an effective electrolysis reaction (Koh et al, 2010), and (ii) the remaining fraction is compressed by a two-stage compressor (storage pressure 30 atm) before being stored in a hydrogen/synthesis gas storage tank.…”