CO₂ Hydrate Capture and Transport
Development of formation and transportation techniques for CO₂-hydrate slurry
Heat transfer and pressure drop characteristics of CO2 mixtures in a pipeline under the seawater condition
Heat Transfer Coefficient and Pressure Drop of Supercritical Carbon Dioxide with Impurity under Seawater Transporting Conditions
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이산화탄소- 하이드레이트를 이용한 수송기술 개발
Development of formation and transportation techniques for CO2-hydrate slurry
In recent years, phase change materials (PCMs) have been applied in various energy storage fields.
Gas hydrates, in particular, exhibit very high thermal characteristics compared to other PCM materials; that is, they have a much higher latent heat than conventional PCMs.
At the same time, there is growing nationwide interest in reducing carbon dioxide emissions into the atmosphere. Accordingly, CCS (Carbon-dioxide Capture & Storage/System) technologies—which include the capture, transport, and long-term storage of CO₂—are being actively developed.
For transporting large quantities of captured CO₂, pipeline transport is being considered. However, achieving the high transport pressure requires substantial power input through compressors, and transport near 100 bar leads to high pipeline installation costs and raises concerns regarding safety.
To address these issues associated with transporting supercritical CO₂, a slurry transport method using multiphase flow based on CO₂ hydrate formation has been proposed. In particular, if hydrate technology is applied starting from the CO₂ capture process, it is expected to offer even greater economic advantages.
◇ Research Method and Experimental Setup
The experimental apparatus consists of:
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A double-pipe heat exchanger for the formation and circulation of CO₂ hydrate,
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A tank that partially stores the generated CO₂ hydrate and supplies the initial water and CO₂, and
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A pump and various measurement sensors.
In this study, we investigated the stable formation and circulation of CO₂ hydrate slurry as a working fluid in an indirect secondary fluid cooling system. In addition, we proposed a pipeline transport method in hydrate form as a more efficient and economical way to transport captured CO₂, and conducted the study based on this concept.
◇ Research Results
The study was carried out using the approach described above, and a lab-scale experimental setup was constructed to perform transport experiments. The main results are as follows.
CO2 HYDRATE SLURRY TRANSPORTATION IN CARBON CAPTURE AND STORAGE
◇ABSTRACT
Based on a proposed hydrate-based gas separation and the utilization of this technology, CO2 hydrate slurry transportation in pipeline from capture plants to storage sites is proposed in this paper. Two different transport processes are considered in the present study. The concept of CO2 hydrate slurry transportation in pipelines has many advantages over the current approaches of CO2 transportation. Transferring CO2 in hydrate slurry status reduces energy input for transportation and eliminates of hydrate blockage in pipelines thus reducing the overall cost of gas transportation. The effect of CO2 hydrate slurry formation in the absence and presence of anti-agglomerants is investigated in an experimental flow loop. The effect of four low dosages of 0.3, 0.5, 0.7 and 1.0 wt% of anti-agglomerant; Tween 80 (non-ionic surfactant) on CO2 hydrate is investigated. Discussions on CO2 hydrate formation kinetics, induction time, slurry density and slurry flow within the experimental loop are provided. In the experiment, hydrate mass fraction ranged from 8 to 32%. The result indicates that CO2 hydrate slurry flow and circulation in the flow loop is significantly enhanced with anti-agglomerant.
Heat transfer and pressure drop characteristics of CO2 mixtures in a pipeline under the seawater condition
◇ABSTRACT
Captured CO2 from CO2 emission sources contains impurities such as N2, CH4, H2O, O2 and Ar, and these are transported with the CO2 in pipelines under supercritical condition. The aim of this study is to experimentally investigate the effects of impurities in CO2 + N2 and CO2 + CH4 on the in-tube heat transfer and pressure drop under seawater environmental conditions during pipeline transportation. The experimental apparatus consisted of a test section, heat exchangers that were connected to two chillers, and a magnetic gear pump. The test section was made by a cooper tube that was inserted into a Polyvinyl Chloride (PVC) pipe to form a double-tube. The operational temperature and pressure of the CO2 mixture ranged 25–55 °C and 80–100 bar, respectively. The mass flux was varied by 300, 500, and 700 kg m−2 s−1. The mole fraction of CO2 in the CO2 mixtures was varied from (1.00–0.95). When the CO2 mole fraction decreased from 1.00 to 0.95, the maximum heat transfer coefficients of CO2 + N2 and CO2 + CH4 decreased by 4157 and 1224 W m−2 K−1, respectively, and the average pressure drop of CO2 + CH4 increased by 29.87%.
해상 수송조건에서 초임계 이산화탄소의 불순물에 따른
관 내측 열전달계수 및 압력강하 특성 연구
Heat Transfer Coefficient and Pressure Drop of Supercritical Carbon Dioxide with Impurity under Seawater Transporting Conditions
◇ Research Background
Recently, as issues related to greenhouse gases have come to the forefront, interest in CCS (Carbon Capture & Storage) has been increasing. In CCS technology, transported CO₂ is typically conveyed over several hundred kilometers in a supercritical state through pipelines for long-distance transport. In the supercritical state, the thermal and transport properties of CO₂ change dramatically with temperature and pressure, and the concentration of impurities varies depending on the capture method, which in turn alters the property trends.
Such severe variations in thermal and transport properties can lead to pipeline rupture, significant changes in pumping power, abnormal behavior, and ultimately transport failure. Therefore, research on the properties not only of pure CO₂ but also of CO₂ containing impurities is essential.
◇ Research Method and Experimental Setup
The experimental apparatus consists of a test section for measuring the heat transfer coefficient of CO₂ containing impurities, a condenser section to liquefy CO₂ before it enters the pump, and a heating section to adjust the test conditions.
In this study, under marine transport conditions for CCS (Carbon Capture & Storage), the heat transfer coefficient and pressure drop of CO₂ were experimentally measured and analyzed for various parameters, with the aim of providing fundamental design data for transport facilities.
◇ Research Results
This study was conducted as described above, and the main findings are as follows:
(1) As the mass flux increased, the heat transfer coefficient of CO₂ increased overall, and the maximum increase rate of the heat transfer coefficient was 11.9%.
(2) As the mass flux increased, the pressure drop of pure CO₂ also increased, with an average increase rate of 86%.
