Power Input of Pitched and Double-Stage Paddle Impeller in a Agitated Vessel

교반조에서 경사 및 2단 Impeller의 교반소요동력에 관한 연구

  • 이영세 (영남전문대학 화학공업과) ;
  • 김문갑 (상주산업대학교 화학공학과) ;
  • 김종식 (계명대학교 화학공학과)
  • Received : 1995.06.02
  • Accepted : 1995.12.01
  • Published : 1996.02.12

Abstract

Power input in stirred vessel is especially important in the design of mixers, as well as the evaluation of mixing processes. A type of baffles in mechanically agitated vessels and power employed are major factors that determine the stirring efficiency in a large scale, multi-step processes. In the present study, power input in the totally baffled agitated vesseles was compared systematically in connection with several previous studies and adequate power input correlation was found to be : $Np_{(pitch)}=({\theta}/90^{\circ})Np_{(90^{\circ})}$ Power number correlation was dependent upon the distance of among the impeller in the agitated vesseles, as follows : $$Np=7.09(n_p)^{0.7}(\frac{b_(double)}{d})(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$<2 $$Np=8.73\{(n_p)^{0.7}(\frac{b_{(double)}}{d})\}^{0.7}(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$>2.

교반소요동력은 장치의 설계상 중요할 뿐만 아니라 교반 프로세스를 평가, 검토하는 데 매우 중요하다. 특히 실험실 레벨에서 플랜트로의 스케일업은 주로 동력기준으로 행해지기 때문에 장치형상의 선택과 동력의 설정이 교반효과를 결정한다. 따라서 본 연구에서는 난류역 완전방해판 조건하에서 경사 임펠러 및 2단 패들 임펠러의 적절한 동력상관식을 제시한다. $$Np_{(pitch)}=({\theta}/90^{\circ})Np_{(90^{\circ})}$$ 또한 임펠러 사이의 거리에 따른 동력수의 추산식을 제시한다. $$Np=7.09(n_p)^{0.7}(\frac{b_(double)}{d})(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$<2 $$Np=8.73\{(n_p)^{0.7}(\frac{b_{(double)}}{d})\}^{0.7}(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$>2.

Keywords

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