An Alternative CO₂ Capture with a Pressure Swing Amine Process Driven by Cryogenic Pumping with the Unused Cold Energy of Liquefied Natural Gas

Abstract

This paper presents an alternative concept of CO 2 capture that can substantially reduce the energy required for CO 2 capture by utilizing unused cold energy. The heat of vaporization of liquefied natural gas (LNG), of which the boiling point is 110 K, is a possible candidate for unused cold energy. This technology is based on a pressure swing amine process combined with a sublimation tank to cool CO 2 released from a desorber into dry ice by exchanging the LNG cold energy. The feature of this technology is that pure CO 2 is recovered mostly by a pressure swing that decreases the pressure in the desorber utilizing a cryogenic pump with CO 2 sublimation instead of a mechanical pump. We developed an amine-based absorbent that can realize the proposed process for exhaust gas from a fossil fuel-fired power plant. A process simulation indicated that the required energy is as low as 0.25 GJ/ton CO 2 when both the absorber and the desorber are operated at around 313 K, the desorber pressure is reduced to 1 kPa, and the sublimation tank is operated at 150 K.

High-Throughput CO2 Solubility Measurement in Miscible and Liquid–Liquid Phase Separation Types of Amine Solvent Using Headspace Gas Chromatography

“…The experimental setup was described in other publications. 28 A short explanation of the methodology in our system is presented in Section 2.2. Our system can automatically measure the CO 2 solubility in a short time, which is superior in comparison with the batch-type vapor−liquid equilibrium and flow-type methods.…”

“…HS-GC conditions are summarized in the previous report. 28 Figure 6 shows the results of the equilibrium solubility measurement of MEA and MDEA and the comparison with literature values. The experimental data showed a good agreement with the literature data, thus confirming the accuracy of this HS-GC method.…”

“…However, if this cold energy is applied in the regeneration tower, it helps to convert CO 2 into dry ice, from which CO 2 is regenerated voluntarily without any thermal energy. 28 As a result, this energy conservation reduces the total energy consumption compared with the conventional temperature-swing regeneration method. In this article, the CO 2 solubility of this solution was measured in the range of lean-to rich-CO 2 loading to predict its absorption heat and cyclic capacity for future applications (Figure 7).…”

“…As reported in our previous article, this solution is suitable for the pressure swing process for CO 2 absorption−desorption which necessitates the requirement of CO 2 solubility, cyclic capacity, and the absorption heat evaluation. 28 After being transported to Japan in a liquid state, liquid natural gas is vaporized and used as the fuel. Until now, most of the cold energy in the vaporization process of liquid natural gas has been released into seawater or air.…”

“…The experimental setup was described in other publications . A short explanation of the methodology in our system is presented in Section .…”