A Study of Carbon-dioxide Removal due to Sublimation Utilizing LNG Cold

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The world CO_2 emission associated with primary energy use has increased more. From the environmental viewpoint, it is a very important problem to reduce the CO_2 emission. Up to the present, many methods due to absorption and adsorption processes have been presented relating to the CO_2 removal. In this report, we have investigated the removal of CO_2 in combusion gas due to sublimation.The results obtained here are summarized as follows ;(1)we have presented new system of CO_2 removal due to sublimation by using the cold source of LNG(liquefied natural gas), which is used as fuel at the fossil fuel fired power generation plant. The removal method is divided into two systems, direct and indirect sublimation systems.(2)As a basic study of the system, frost deposition occurring with mist formation has been investigated experimentally and theoretidcally. Mist migration due to thermophoresis and gravity force plays an important role on mass transfer in mist flow. Based on a model considering mist migration in saturated air flow, mass transfer coefficients have been presented.(3)Frost deposition of CO_2 and H_2O vapors has been investigated. The process was divided into two periods, composite frost growth period and H_2O frost growth period. Frost deposition has been predicted based on a model which is composed of CO_2 and H_2O frosts and is considered internal diffusion of both vapors.