uu RAO DOI Xac djnh ton ap cua tac nhan qua \6p hat mud1 tinh qua trinh say b^ng may say tang soi lien tuc (*) BUI TRUNG THANH (**)NGUY6NHAY Gidi thieu Hat vat lieu riin hda sdi ddng xay cd mdt ddng cd van tdc, cd ap suat du Idn, di chuyen theo hffdng tff dffdi len qua ldp hat vat lieu thdng qua mdt ghi phiin phdi (distributor) gdm vd so'cac Id phiin phd'i dffdc bd tri d day ldp vat lieu hat Ddng dffdc thdi tff mat diiy ldp hat, di xuyen qua cac hat thdng qua nhffng khoang trdng giffa cac hat vat lieu lam mat dp cua khdng gian hat giam di, nhffng khdng liim iinh hffdng den nhffng tinh cha't can biin cua ldp hat Khi van tdc ddng thap, ap lffc tac diing len ciic hat nhd, ldp hat v i n tri va giff nguyen trang thiii tinh ban diiu Khi tang van tdc len, lffc keo ciia ddng xuiit hien ngffdc chieu vdi trpng lffc ciia hat va lam cho ldp hat bat dau gian nd ve the tich, cac hat biit diiu di chuyen tiich rdi xa hinh thiinh ldp hat sdi tdi thieu.Tang van tdc ddng len hdn nffa den giii trj tdi han thi lffc ma sat giffa ciic hat va khdng ciin biing vdi trpng Iffdng hat thiinh phiin thang dffng ciia ap lffc nen triet tieu, lffc keo hffdng len dung bang vdi trpng lffc hffdng xudng lam cho viit lieu Id Iffng ddng tac nhiin thdi qua Tai giii tri niiy dffdc L.T Fan[2] dffdc gpi lii ldp hat biin sdi nghia lii \ a n tdc qua ldp hat cd gia tri Idn hdn \iin tdc hda sdi tdi thieu, tiep tuc tang van tdc len nffa thi Idp \at lieu miy dffdc sdi va hinh thiinh ciic bpt khi(bubbling) \ii dffdc gpi lii ldp hat sdi bpt khi, ldp hat giii long hoan toan Tiep tuc tang van tdc hdn nffa thi miit dp khdi cua ldp hat tiep tuc giiim va sff hda sdi xay manh me cho den viit lieu khdng cdn d dang ket ldp nffa \ii bj cudn len va rdi trd lai chuyen ddng sdi ngiiu nhien Khi hat sdi mdi hat vat lieu dffdc bao phii bdi ddng ndng \-ii thffc hien muc dich trao ddi nhiet trao, ddi am neu ffng dung cho say hat hoac lam ngudi hat Khi ldp hat sdi, xiiy sff hda trcin manh liet giffa va viit lieu hat, ket quii lii tao mdi trffdng ddng deu ve nhiet dp vii dp am toiin bp ldp hat [4] Nham md tii \ e mat lip suiit ciia ddng di qua cac loai ldp h a t , bai bao trinh biiy cac ket qua tinh toan tdn dp ciia ddng qua ldp hat tinh qua ldp hat sdi tdi thieu, qua ldp hat biin sdi va qua ldp hat sdi cua ciic tac giii nffdc va ngoai nffdc da de cap cac cdng trinh khoa hpc nghien cffu vecdng nghe tang sdi, dac biet bai bao trinh bay cac linh toiin cu the ve tdn iip cua ddng hda sdi di qua ldp hat mudi tinh qua tnnh thffc hien sa'y hat ldp hat sdi lien tuc vii thffc hic-n dd'i chieu ciic ket qua tinh toiin ly thuyet vdi cac ket qua thffc nghiem tren md hinh thi nghiem vdi cac loai hat mudi tinh cd cac dffdng kinh hat trung binh lay tff mau mudi tinh ciia cdng nghe nghien -rffa va phan ly thuy lffc cac nha may che bien mudi tinh cao Clip ciia Tong Cdng ty Mudi Viet Nam theo cac cap kich thffdc hat phan bd phamvid=0,225mm;d=,45m; d=0.75mm: d=1.05mm;d= l,35mm:d=l,65mm, ma chung dffdc sff dung de lam ldp dem hd trd qua trinh tao sdi ban dau qua trinh say ldp sdi lien tuc [17] Dir lieu va phifdng phap 2.1 Xac djnh trot li/c ciiia dong tac nhan qua ldp hat tinh Dac tinh trd lffc qua ldp hat tTnh tinh theo cdng thffc thffc nghiem ciia N.M Javorosky [1]: (1) AP,=2(; ^„-P* 2.g. 1000 Burker va Plummer da xac dinh ddng chay rdi da lam sinh tdn thii't nang Iffdng ddng hpc Luc trd lffc qua ldp hat hinh dang khdng cau dffdc tinh theo (PtlO)[8]: (10) (6) P, ^ "g'' Ln(\ + bQ,) )A Trong dd: H^ - chieu cao ldp hat sdi tdi thieu m: H^^- chieu cao Idphat sdi bpt khi, m; e^^-dp xdpcua ldp td trang thai sdi tdi thieu; e^^- phan the tich bpt chiem chd ldp hatd trang thai sdi bpt Ap suat khdng ddi sudt tff trang thai ldp hat sdi tdi thieu den trang thai sdi hdp ly (tff A-B Hinh 1) Trong each tinh tdn ap qua ldp hat (Ptl2)chu yeu phu thupc vao khdi lffdng rieng ciia loai hat va dp xdp ciia hat trang thai sdi tdi thieu Trong dd Ergun lai dffa phffPng trinh tinh tdn ap ciia ddng di qua ldp hat cd hinh dang bat ky trang thai sdi td'i thieu (vi tri A hinh 1) biing (PT12)|4|: k,.^,(\-£^)\^ (13) ey'iV'd;) Trong dd: APt- trd lffc qua ldp hat tTnh ;kg/m-; k^-la hang sd thffc nghiem khdng thff nguyen vt- van tdc ddng qua ldp hat tTnh, H„- chieu cao ldp hat trang thai tTnh; E„ - dp rdng ldp hat trang thai tTnh Trong nhieu thffc nghiem blacke-Kozeny da xiic dinh k = 150 Pham vi sff dung (Ct 8) ciia Blake-Kozeny Re< 10 va dp rdng ldp hat trang thiii tinh t:„ = 0.5 dd he sd Reynol (Ret) tffdng ffng dffdc tinh: = cons tan / ^ H 150 [\-E„)- j " ^ ^ , i l l ^ ) Av,/ [