Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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Conceptual Design and Hydrodynamic Properties of a Moving Bed Reactor for Intrinsic $CO_2$ Separation Hydrogen Production Process

$CO_2$ 원천분리 수소 제조 공정을 위한 이동층 반응기의 개념 설계 및 수력학적 특성

  • Park, Dong-Kyoo (Department of Chemical and Biomolecular Engineering, Energy and Environment Research Center, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Cho, Won-Chul (Department of Chemical and Biomolecular Engineering, Energy and Environment Research Center, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Seo, Myung-Won (Department of Chemical and Biomolecular Engineering, Energy and Environment Research Center, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Go, Kang-Seok (Department of Chemical and Biomolecular Engineering, Energy and Environment Research Center, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Kim, Sang-Done (Department of Chemical and Biomolecular Engineering, Energy and Environment Research Center, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Kang, Kyoung-Soo (Hydrogen Production Research Center, Korea Institute of Energy Research (KIER)) ;
  • Park, Chu-Sik (Hydrogen Production Research Center, Korea Institute of Energy Research (KIER))
  • 박동규 (카이스트 생명화학공학과 에너지환경 연구센터) ;
  • 조원철 (카이스트 생명화학공학과 에너지환경 연구센터) ;
  • 서명원 (카이스트 생명화학공학과 에너지환경 연구센터) ;
  • 고강석 (카이스트 생명화학공학과 에너지환경 연구센터) ;
  • 김상돈 (카이스트 생명화학공학과 에너지환경 연구센터) ;
  • 강경수 (한국에너지기술연구원 수소제조연구센터) ;
  • 박주식 (한국에너지기술연구원 수소제조연구센터)
  • Received : 2011.02.22
  • Accepted : 2011.03.10
  • Published : 2011.03.31
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Abstract

The intrinsic $CO_2$ separation and hydrogen production system is a novel concept using oxidation and reduction reactions of oxygen carrier for both $CO_2$ capture and high purity hydrogen production. The process consists of a fuel reactor (FR), a steam reactor (SR) and an air reactor (AR). The natural gas ($CH_4$) is oxidized to $CO_2$ and steam by the oxygen carrier in FR, whereas the steam is reduced to hydrogen by oxidation of the reduced oxygen carrier in SR. The oxygen carrier is fully oxidized by air in AR. In the present study, the chemical looping moving bed reactor having 200 L/h hydrogen production capacity is designed and the hydrodynamic properties were determined. Compared with other reactors, two moving bed reactors (FR, SR) were used to obtain high conversion and selectivity of the oxygen carrier. The desirable solid circulation rates are calculated to be in the range of $20{\sim}100kg/m^2s$ from the conceptual design. The solid circulation rate can be controlled by aeration in a loop-seal. To maintain the gas velocity in the moving beds (FR, SR) at the minimum fluidization velocity is found to be suitable for the stable operation. The solid holdup in moving beds decrease with increasing gas velocity and solid circulation rate.

[ $CO_2$ ]원천 분리 수소제조 반응시스템은 금속 산화물의 산화/환원 반응을 이용하여 기존의 수증기-메탄 개질 반응을 3단계의 반응시스템으로 분리함으로써 메탄 연소 시 발생되는 $CO_2$를 원천적으로 분리함과 동시에 고순도 수소를 별도의 후단 공정없이 직접 생산해 내는 신 개념의 수소 생산 기술이다. 반응 시스템은 크게 연료(즉, $CH_4$)가 공급되는 연료반응기(FR: Fuel Reactor), 수증기가 공급되는 수증기반응기(SR: Steam Reactor) 및 공기가 공급되는 공기반응기(AR: Air Reactor)로 구성되며, 다른 반응기와 비교하여 반응 매체의 전환율과 선택도를 높이기 위하여 긴 체류 시간을 확보할 수 있는 두 개의 이동 층(FR, SR)으로 구성되었다. 본 연구에서는 200 L/h의 수소를 생산할 수 있는 매체 순환식 이동층 반응기 제작을 목적으로 수소발열량 기준 0.55kW급 이동 층 반응기의 개념 설계 및 cold model을 설계 제작하고 주요 운전 변수에 따른 수력학적 특성을 결정하였다. 개념 설계 결과 원하는 매체 전환율을 얻기 위해 필요한 고체 순환속도범위($20{\sim}100kg/m^2s$)를 결정하였다. Cold-model 실험 결과, loop-seal의 유속이 증가함에 따라 고체 순환 속도가 증가하였으며 이를 통하여 고체 순환속도 조절이 가능하였다. 반응시스템의 안정적인 조업을 위해서는 이동층(FR, SR) 조업 조건을 최소 유동화 속도 부근으로 유지하는 것이 좋은 것으로 나타났다. 이동층 내 고체 체류 량은 기상유속 및 고체 순환 속도 종가에 따라 감소하였다. 본 연구를 통하여 조업조건에서 개념 설계에서 원하는 고체 순환 속도 및 흐름 특성을 얻을 수 있음을 확인하였다.

Keywords

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