化学反应工程与工艺
化學反應工程與工藝
화학반응공정여공예
CHEMICAL REACTION ENGINEERING AND TECHNOLOGY
2014年
5期
404-414
,共11页
射流环流反应器%雷诺应力模型%离散相模型%颗粒悬浮
射流環流反應器%雷諾應力模型%離散相模型%顆粒懸浮
사류배류반응기%뢰낙응력모형%리산상모형%과립현부
jet loop reactor%reynolds stress model%discrete phase model%particle suspension
为确定射流环流反应器中射流所能驱动的环流速度的大小,以此来确定催化剂颗粒的粒度。在二维轴对称假定下,采用雷诺应力模型(RSM)模拟考察了导流筒与反应器直径比(De/D)、反应器底部型式、射流口与导流筒下缘距离(Hn)的变化对环流流量与射流流量比(RQ)的影响,并结合离散相模型(DPM),模拟了不同几何结构,不同射流速度下,不同粒径催化剂颗粒的悬浮情况。研究表明,De/D为0.67时RQ最大,而不同底部型式和Hn下的 RQ相差均低于3.6%,影响可以忽略;但反应器底部的锥形设计以及较低的Hn值有助于改善催化剂颗粒的悬浮状况;按给定的设备结构参数和物性参数,得出了低体积浓度(约0.1%)下实现催化剂完全悬浮于整个设备的临界射流速度(Vnc),建立了Vnc与催化剂颗粒粒径的关联式。通过模拟方法实现了催化剂粒径的设计、射流速度的选择和设备结构的优化。
為確定射流環流反應器中射流所能驅動的環流速度的大小,以此來確定催化劑顆粒的粒度。在二維軸對稱假定下,採用雷諾應力模型(RSM)模擬攷察瞭導流筒與反應器直徑比(De/D)、反應器底部型式、射流口與導流筒下緣距離(Hn)的變化對環流流量與射流流量比(RQ)的影響,併結閤離散相模型(DPM),模擬瞭不同幾何結構,不同射流速度下,不同粒徑催化劑顆粒的懸浮情況。研究錶明,De/D為0.67時RQ最大,而不同底部型式和Hn下的 RQ相差均低于3.6%,影響可以忽略;但反應器底部的錐形設計以及較低的Hn值有助于改善催化劑顆粒的懸浮狀況;按給定的設備結構參數和物性參數,得齣瞭低體積濃度(約0.1%)下實現催化劑完全懸浮于整箇設備的臨界射流速度(Vnc),建立瞭Vnc與催化劑顆粒粒徑的關聯式。通過模擬方法實現瞭催化劑粒徑的設計、射流速度的選擇和設備結構的優化。
위학정사류배류반응기중사류소능구동적배류속도적대소,이차래학정최화제과립적립도。재이유축대칭가정하,채용뢰낙응력모형(RSM)모의고찰료도류통여반응기직경비(De/D)、반응기저부형식、사류구여도류통하연거리(Hn)적변화대배류류량여사류류량비(RQ)적영향,병결합리산상모형(DPM),모의료불동궤하결구,불동사류속도하,불동립경최화제과립적현부정황。연구표명,De/D위0.67시RQ최대,이불동저부형식화Hn하적 RQ상차균저우3.6%,영향가이홀략;단반응기저부적추형설계이급교저적Hn치유조우개선최화제과립적현부상황;안급정적설비결구삼수화물성삼수,득출료저체적농도(약0.1%)하실현최화제완전현부우정개설비적림계사류속도(Vnc),건립료Vnc여최화제과립립경적관련식。통과모의방법실현료최화제립경적설계、사류속도적선택화설비결구적우화。
Suspension of the catalyst particles was studied in a jet loop reactor with computational fluid dynamics method. A 2-dimensional axisymmetry model was adopted with Reynolds Stress Model(RSM) to analyse the effect on the flow rate ratio (RQ) of circulation to jet from the diameter ratio of draft tube to reactor (De/D), geometric structure of the reactor, axial distance of the nozzle and the draft tube (Hn). Then the Discrete Phase Model was used to describe particle suspension against various bottom type,jet velocity and diameter of particles. Conclusions can be drawn from the simulation results:RQ is largest whenDe/D is 0.67 and the deviation ofRQ is below 3.6% when bottom type andHn vary. With cone bottom and lowerHn, particle suspension can be smoothly achieved. With the specified geometric parameters of the equipment and physical property of the two phases, the critical jet velocity(Vnc) that can suspend particles,of low concentration by volume(about 0.1%),in the whole device is obtained through numerical prediction and correlation ofVnc and catalyst particle size is suggested from numerical results.