Trong bai bao nay, tac gia xay dung md hinh md phdng quy hinh gia Idng cac hat ran de say hat mudi tinh trong Idp hat sdi vdi 03 dac tinh co ban: a Trao ddi nhiet; b Chuyen ddng ddng hat
Trang 1NGHIEN cuu - TRAO DOI
GIA LONG CAC HAT RAN DE UfNG DUNG TRONG SAY WIUOI TINH
BANG LdP HAT SOI LIEN TUG
THE FLUIDIZATION OF SOLID PARTICLES FOR APPLICATIONS
TO REFINED SALT IN THE CONTINOUS FLUIDIZED BED
TS Bui Trung Thanh
Khoa Cong nghe Nhiet lanh, Traong Dai hoc Cong nghiep TP H6 Chi Minh
TOM TAT
Ky thuat lam gia long cac hat vat lieu roi duffc img dung nhieu trong thuc tien nhu: Say tdng soi, tao hat trong lop soi hoc vien nang bang lap soi trong nganh Duoc pham va dot nhien lieu trong lo dot lap hat soi
Trong bai bao, tac gia trinh bay cac dac tinh cua phuang phap "gia long " va ihtg dijng de xay dtpig
mo hinh say mudi tinh trong lop hat soi Tic mo hinh toan tac gia da tien den thuc hien thiet ke, che tao
va thuc nghiem say mudi tinh tdng soi vai ndng sudt sdy 3.000 kg/gia trong san xuat thuc tien
Tir Khoa: Gid long; Trao doi nhiet; Dong hat; Tdng soi; Mdy sdy mudi tinh
ABSTRACT
Fluidization of solid particles ts the operation by which solidparticles are transformed intofluidized state This method of contacting has some unusual characteries and in practice, it's engineering puB them to good use
In this paper, an expansion for fluidization of solid particles for drying on thefluidized is given: Method, modeling, comparison, expriment in Lab and industral Techonologyfor drying with its capacity
is 3.000kg refined salts by an hour
Keywords: Fluidization; Fluid-solid; Heat transfer: Fluidized bed drying, refined Salt dryer
TAP CHi CO KHi VIET NAlVt, S6 3 nam 2014
Trang 2NGHIEN CUU - TRAO DOI
1 BAT VAN DE
De lam khd mudi tinh sau cdng doan nghiln,
nia, ly tam ngudi ta phai thuc hien s4y khd chung
bang each: Say rang (ung dung nguyen ly truyin
nhiet d§n nhiet kk hop vdi s4y ddi lim) cdn goi
la say tiep xiie bang, may say thung quay cd cac
canh dao tron cd gan gan bi de go chdng dinh bam,
hoac say tren may say rung (ung dung nguyen ly
truyen nhiet ddi luru)
Trong thuc te cdn cd th6 sSy chung bSng
phucmg phap say tang soi, phuang phap sSy
tang soi khdng can khuay, khong can dao trdn,
khdng can rung De say dugc Idp mudi tinh bang
phuang phap say nay, ngudi ta phai thuc hien
lam gia Idng cac hat ran, nham tao ra su ddng
nhat ve nguyen vat lidu Khi say hat d trang thai
sdi gia Idng, cac hat dugc nhan nhiet bang truyen
nhiet ddi luu khi - hat, truyen nhiet dan nhiet va
bue xa hat-hat va truyen nhiet dan nhiet hat vdi
be mat ndng [10] Cac each truyen nhiet nay lam
cho am nhanh chdng dugc tach ra khdi be mat
hat de hat nhanh chdng dugc lam khd, trd thanh
san pham cd kha nang luu trii dai ngay cho qua
trinh sur dung
Thdng thudng de say cac hat rin bang Idp hat
sdi, ngudi ta che tao cac may say dang hinh tru,
cd chidu cao tuy thudc theo kich thudc va loai san
phim cin s^y Trong [3], tac gia dd xuat phuang
phap sdy ting sdi say khdi hat mudi tinh cd tiet
dien dang "hinh nam" Tiet dien mat ck ngang
cd dang dudng cong thoai thoai, hep dan tu tren
xudng va da thu dugc ket qua: Chat lugng hat say
dat tieu chuin ky thuat, hieu suat say cao va chi
phi cho san phim cd gia thanh thip
Trong bai bao nay, tac gia xay dung md hinh
md phdng quy hinh gia Idng cac hat ran de say hat
mudi tinh trong Idp hat sdi vdi 03 dac tinh co ban: (a) Trao ddi nhiet; (b) Chuyen ddng ddng hat; (c) Tdn ap cua ddng klii qua Idp hat sdi
2 DC LIEU VA PHlTONG PHAP NGHIEN ClTU
2.1 Phuimg phap gia long cac hat ran
Mot quy luat cua tir nhien la cac chat Idng va chat khi ludn tuan thu nguyen ly khi ddng hgc: Cd
su ddng nhat ve cau true cac phan tu; tao khudn
de dang vdi thiet bi dung dd dung; Cd ddng chay Cdn ddi vdi chat ran thi cd cau true khdng ddng nhat, nhin thay bang mat thudng dudi dang hat Ngoai ra, cac hat san pham can say khd bao gid ciing cd do am cao, cd dp ket dinh cao Phuang phap gia long cac hat ran dua tren cac khai niem [10]
Dinh nghia 2.1: Dudng kinh cac hat ran dugc
xac dinh la do dai Idn nhat cua cac hat nguyen lieu dua vao may say, dugc ky hieu bang d > 0 (diameter of particle)
Djnh nghia 2.2: Do rdng gitta cac hat la
tinh tach biet giiia cac phan tu', dugc xac dinh la khoang each giiia cac hat, dugc ky hieu bang s >
0 (fraction of the bed volume)
Djnh nghia 2.3: Tang roi cac ddng hat la tang
ma d dd sau khi hat nhan nang lugng se tang ndi nang va chuyen ddng khdng theo quy luat, dugc
ky hieu bang h^^ > 0 (higher of tubulent level)
Djnh nghia 2.4: Tang chuyen tiep cac ddng
hat la tang ma d do sau khi thoat khdi ting rdi, cac hat bat dau chuyen ddng theo hudng len, dugc ky hieu bang h^^ > 0 (higher of transitional level) Tang nay cung cd ten ggi la tang ban sdi
' CHI CO KHi VIET NAM, S6 3 nam 2014
Trang 3NGHIEN cuu-TRAO001
Hinh 1: Lap hat mudi tinh dang soi trong dong
tdc nhan khi nong trong mo hinh thi nghiem
duac tdc gid thiet lap dimg trong thi nghiem
Dinh nghia 2.5: Ting sdi la tang ma d dd cac
hat rin cd dac tinh nhu chat Idng (gia long) dugc
dun va sdi, dugc ky hieu bang hfb > 0 (higher of
fluidized bed level)
Djnh nghia 2.6: Say trong Idp hat sdi la tach
i m tir cac hat ran bang each truyen nhiet ddi luu
khi - hat dudi trang thai Idp hat sdi bdng benh
trong ddng khi ndng, am tit hat ran thoat ra va di
theo ddng khi thai ra ngoai hudng say
2.2 S^' truyen nhiet trong lap hat ran cua Idp
soi
Truyen nhiet trong lap hat ran thudng xay ra
qua ba hinh thuc: Truyen nhiet dan nhiet, truyen
nhiet ddi luu va truyen nhiet biic xa Thuc te do
nhiet dp say tac nhan say thap, ta chi can quan tam
hai dang dudi day
2.2.1 Phuang trinh truyen nhiet doi luu
Sat be mat cac hat chat ran thudng cd mot
Idp mdng chat khi khdng chuyen ddng, ngudi ta
ap dung dinh luat Fourier doi vdi Idp ay nhu sau:
TAP C H i CO KHI VIET NAM, S6 3 n a m
Q,.=-P(|^)UP-'^
an
Mat khac, gia sii nhiet dp toan phan ciia Idli,
hat trong may s^y la t = i(-x^,x^,^,), nhiet do
ciia tac nhan khi th6i vao bu6ng say kho la tg > 0, Nhiet ciia hat la t , sir chenh lech vfi nhiet nay co
thS xkp xi lien tuc la d t = t , - t^va moi trucmg
hat CO he s6 truyen nhiet doi lira la a, khi do ta co sir bijn d6i nhiet ciia truyin nhiet d6i lira Q^^ se la:
dt
; (2.2)
Khi do nghiem cua phuong trinh (2.2) la;
Q „ = « ( t = - t p ) (2-V
Can bang cac phuang trinh (2.1)- (2.3) ta co
he s6 trao doi nhiet doi luu:
He sd trao ddi nhiet ddi luu thuc te thudng
do dugc bang thuc nghiem, vi du theo Bolter! [5] dugc tinh theo cdng thuc c:
a = a = 35,8.p'".?L"'.d-°''' (2.5)
mnx ' '^P P P ' '
Trong dd:
p ^ - Khdi lugng rieng cua hat ran, kg/m^
X
I' - Dd dan nhiet cua hat ran,W/m dp Bang md hinh nay, tac gia da ap dung tinh cho say hat mudi tinh
- Nhiet lugng trao ddi dugc tinh theo cong thuc (2.3) vdi he sd cua (2.5):
Q^^ - a(t^ - t^,)= [35.8.p;'.^p".d;""']x (160 - 31,2) (2.6^
Trong dd: Nhiet dp t - 160 °c
Nhiet dp hat s i y liy t - 31,2 °c
2014
Trang 4NGHIEN cuu-TRAODOI
2.2.2 Phuang trinh viphan nang luang
Gia sir chat (hat) gia Idng la ddng nhat, khdng
bi nen, ngudn nhiet la nhiet lugng cua cac hat
bien ddi sau khoang thdi gian dx The tich cua
hop chua chat Idng trong klidng gian ba chieu do
dugc dv = dx^.dx^-dx^
Khi dd, theo tung phuang, ta lap phuang trinh
vi phan nang lugng cd dang:
thu nhiet vao:
dQ^ = q^dx, dx, dx^, j = 1.2,3 (2.7)
Tda ra:
dQj^,i,^ = q^^,^ dXj.dx^.dx^^, j = 1,2,3 ^2 S)
Nhiet lugng tich tu lai trong cac hat theo
phuang trinh (2.8)
Nhiet lupng tich ha lai trong cac hat theo
phuang x , j - 1,2,3 dugc xac dinh bdi (Pt 2.9)
dQ -dQ, , ^dv.dT ] = l,2.5 (2.9)
J
Bing md hinh nay, tac gia [2] da ap dung de
tinh toan siy va thu dupe ket qua thuc nghiem
nhu sau:
- Nhiet cua khdng khi trudc khi vao budng
ddt la t^ -30 °c;
- Nhiet ciia khi dugc gia nhiet thanh tac nhan
say cap vao budng say t^- 160°c;
- Nhiet cua khi tren dudng dng thai am la t,^
850c;
- Nhiet cua hat ran trudc khi vao budng say
la e„-32,l°C;
- Nhiet ciia hat ran trong budng say la 9| =120
°C;
TAP
- Nhiet cua san pham khi ra khdi budng say
la 9, = 70OC;
Chii y: Trong hoat ddng say tren tang sdi, tac
nhan say d nhiet dp 600"C thi thanh phan truyen nhiet biic xa mdi bat dau trd nen dang ke [8], ma trong trudng hgp say mudi tinh, nhiet dp gidi han nhd ban 200^^ C, nen ta khong cin xet he sd trao ddi nhiet buc xa [4]
2.3 Chuyen dong ciia dong hat
2.3.1 Thong so ky thuat cac hat say
+ Kich thudc hat say (xem dinh nghia 2.1),
can phai chu y den kich thudc cua hat ran can say, vi du, ddi tugng cd the la hat dudng cat, hat me, hat mudi tinh (trong say tang sdi thudng ung dung de say cac hat cd kich thudc be thi cd hieu qua cao)
+ Do rdng giua cac hat (xem dinh nghia 2.2):
Do dac tinh ran, nen giira cac phan tu bao gid ciing cd khoang each Idn han 0 (E > 0) Do rdng cang Idn thi thdi gian qua trinh gia Idng cac hat ran cang keo dai va tieu tdn nang lugng nhieu hon + Phan tang hat ran (xem cac dinh nghia 2.3-2.5): Khi dua khi vao budng say cung vdi nhiet va van tdc khi cd the tao ra 03 tang hat ran: Tang rdi, tang chuyen tiep va tang sdi
Ddi tugng ciia nghien cuu nay la hat mudi tinh cd cac thdng sd ky thuat trinh bay trong [2]
- Do xop cita hat trang thai tir nhien £ = 0,5= 0,52;
- Khdi lugng rieng cua hat: p - 2018-2014kg/
- Khdi lugng the tich cua hat udt p^^ -982 kg/
CHI CO KHI VIET NAM, So 3 nam 2014
Trang 5NGHIEN CirU-TRAO DOI
- Dp ciu cua hat d 30 °c (p = 0,67^0,74, lay
trung binh 0,71;
- Chi§u cao Idp hat nguyen lieu: 45mm;
- Chi^u cao Idp hat hda sdi tdi thieu: 49.5cm;
- Khdi lupng mudi khd tam Idp dem trp sdi
:15kg;
- Dudng kinh trung binh d= 0,956mm
2.3.2 Van tdc dong hat hoa soi
Gia su mdi chat lam gia Idng khdi hat la ddng
nhat, khdng bi nen, ngudn nhiet la nhiet lupng cua
cac hat bidn ddi nhu trong phuang trinh trao ddi
nhiet va phuang trinh nang lugng Khi cd "ddng
chay" - "cac hat ran" trong may say thi tuang
tac ddng nang, trao ddi nhiet,v.v , tiep tuc xay
ra trong qua trinh say cd the giup tiet kiem dupe
ngudn nang lupng dau vao, nham ha gia thanh san
pham Dudi day la cac thdng sd ky thuat van tdc
ddng hat mudi cd kich thudc trung binh:
d = 0,953mm dugc say trong lap hat sdi
[6],[7]
- NSu ta chon he sd Archimed Ar ^ 8.818,4;
He sd Renolds Re = 30,4065 thi van tdc hat tren
Idp ban sdi (Idp chuyen tiep) la v^== l,5m/s [8], thi
gia tri van tdc tdi han the bi cudn di theo khi thai
ra ngoai cd gia tri:
- Van tdc tdi han (v^j^) cua ddng hat udt la v^,^
= 2,3m/s
- Van tdc khi sdi tdi thieu v — 4,5m/s
- Tuang ung vdi dp rdng Idp hat sdi tdi thidu
£^=0,56
2.3.3 Van tdc lan truyen nhiet qua lop soi
Gia su chat (khdi hat) gia Idng bay gid la ddng
TAP CHi CO KHI VIET NAM, S6 3 nam 2014
nh4t, khdng bi nen, khi dd su bidn thien nhiSt dp cua budng say la:
dt af -f af 3x
Trd-.'ld^-i^<'-^^
thdi diem la:
Dac trung cho su bien thien nhiet dd tai mpt
di
dl
+ Dac trung cho su bien thien nhiet dp theo thdi gian la:
^ af 3x
trax^ dx ' ^
Vdi van tdc lan truyen nhiet:
'dx' j-1,2,3 (3.3)
Dudi day la cac thdng sd ky thuat van tdc khi vdi hat mudi loai da phan tan cd kich thudc trung
binh d = 0,956 mm dugc say trong Idp hat sdi co
cac gia tri van tdc theo [7]
-Van tdc khi qua Idp hat soi tdi thidu v^ =
0,45m/s, tuang ung vdi do xdp trang thai Idp hat sdi tdi thieu e^^ - 0,56;
-Van tdc sdi hgp ly cua hat;
•'opt ^ 0,9-1,6 m/s (van tdc tinh toan theo ly thuyet trong [7] la >'„, = 1,33 m/s
2.4 Ap suat trong budng siy 2.4.1 Ap suat khi qua Idp hat
Viec tinh toan ap suat khi qua Idp hat (P) cSn phai doTi gian, gia thiet rang Idp hat gia Idng b5y gid la ddng nhat, khdng bi nen
Dau tien la xac dinh luc tac dung len ph5n tii chat Idng cd th6 tich dv = dx^.dx^.dx^ gdm cd ba loai: Trgng luc, ap suat va ma sat
Trang 6- Lire ciia trong truong (dPj) theo phucmg x,
xac dinh boi:
D6i voi chdt long nhot khong chiu nen co the
ap dung he phuang trinh Navier - Stocks:
dPj = g^^dXjdx^dXj (4,1)
-Luc ap suat ( dP ^) bao g6m:
Luc ap suat ep ISn be mat tren ciia cac phan
Luc ap suat ep len be mat duai cac phan tir
la - ( P H d x , ) d x , d x , theo cong thiic:
dx, •'
dP, =Pdx,dX3 - ( ? + — d x , ) d x , d x ,
dx, ' ' '
d P
" d x dv (4.2)
- Luc ma sat (dP^) xuat hien theo phuang X^
Gia su tiet dien be mat phan tir la s, khi do phan
theo
phuongXjla s.dx^dx^, phan theo x^ + d x , la
(s H ) d x , d x , , do do luc ma sat:
d x / ' '
dP ={s + —4x,)(lx,dx, -sdxdx =—Ay.M,iy.J4.3)
' dxj ' ' ' ' ' dx, ' - '
Vi lire ma sat co the tinh tren mot don vi dien
d P ,
dm
= H - - i (4.4)
dx^
d^to
nen " ' s ' U ^ ^ d v (4.5)
(dxj)
Vay:
dP d'o)
-' dx, (dx.^)
T u a n g tu xet theo cac phuong cdn lai ^2' ^3
p^=pg-VP+\iV\6}' (4.7)
dx
2.4.2.Tdn dp trong lop soi
Co che tao ra hat sdi trong ddng khi chi xay ra
khi ddng khi thdi qua Idp hat theo hudng tu dudi len thdng qua ghi phan phdi khi (gdm vd sd Id phan phdi khi bay len), cd van tdc va cd ap suat dii Idn Neu van tdc cua ddng klii qua nhd, ap luc tac ddng len hat ran khdng dang ke thi hat ran van giii nguyen trang thai Nhung neu tang van tdc khi, tang ap luc len hat ran thi cac hat ran tach rdi nhau
va di chuyen thanh ddng Neu tang van tdc khi den gia tri tdi han thi luc nang cua khdng khi can bang vdi frpng lugng cua hat, thanh phan thang dimg cua ap lire nen bi tnet tieu, luc nang bang dung trgng lugng cac hat va se xuat hien trang thai l a lung cua hat ran Hien tugng nay, dugc gpi
la sdi Tang sdi nay, cd ba Idp: Ldp ban sdi; Ldp sdi va ldp hot khi Ban sdi la Idp khi cac hat ran bat dau la limg - sdi, Idp sdi la ldp can bang hoan toan ap luc len hat va trgng luc, cdn ldp hot khi
la ldp khi cdvan tdc tang len lam cho cac hat ran
bi cudn len manh me Tuy thudc vao van tdc khi thdi qua Idp hat ma trong ldp hat sdi xuat hien cac tdn that ap suat
Trong bai bao [6], tac gia da tinh toan tdn ap cua ddng tac nhan khi qua cac tang khac nhau: Ldp hat tinh, ldp hat rdi, ldp gifta va ldp hat sdi Dac biet chu y den tdn ap cua ddng khi qua ting sdi AP theo L.T Fan va nhdm tac gia [9]
TAP
Can chu y rang ap suat qua ldp hat vat lieu s tuy thudc vao ba thdng sd
CHI CO KHI VIET NAM, Sd 3 nam 2014 M
Trang 7NGHIEN cuu-TRAO DOI
(a) Kich thudc hgt (d^) cac phSn hi mm lan
trong khdi hat, ngu hat cd nhidu tap ch§t min, thi
tdn ap Ap se tang; (b) Chik cao ldp hat
(c) Do xdp cua khdi hat (s) each dua hat v^o
budng sSy dudi dang hi nen chat cung deu lam
tang trd lire Ap va dp nhdt ddng luc hgc cua tac
nhan khi hda sdi tdi thieu
P=f(d^:H,;e,,mJ (4.9)
Ddi chi8u vdi di6u kien van hanh trong
thuc t^, khi tmh toan phai tinh bii them bfing each
nhan bidn thien ap sudt AP hi kit qua tinh theo cac
cdng thuc ndi tren vdi he sd cd tinh den cac yeu td
nay K8t qua nghien cuu ciia chung tdi theo hudng
nay da dupe trinh bay trong Bang sd 4 trang
20-Cac thdng sd ky thuat [6]
3 KET QUA NGHIEN ClTU
3.1 May s3y t^ng soi dang me (batch fluidized
dryer)
May sdy cd dang hinh tru (hinh 2) May say
hoat ddng dua tren phuang phap lam ldp hat gia
Idng thuc hien nguyen ly trao ddi nhiet ddi Imi
tach am va lam khd cac hat ran trong ldp hat sdi
Hinh 2: Mdy sdy tdng soi dgng me [1]
TAP CHi CO KHi VIET NAM, So 3 nam
Mot s6 dac diim cua may say dang me + Kha nang trao ddi nhiet, ttao ddi am cao + Thich hop trong siy cac loai hat vat lieu hat
cd do am cao
+ Khdng cdn tinh toan khdng che thdi gian sdy
+ Khd tu ddng hda khau nap lieu va idy san pham
+ San phdm sdy khdng dupe lam mat trudc khi bao quan
+ Nang suat say thap
+ Ty le cac hat bi va cao
+ Thich hpp cho viec tao hat hoac bpc mang bao ngoai cho hat say
+ Chi phi say cao
3.2 Thuc thi thilt ke che tao may say tang s6i lien tuc (Continuous fluidized dryer) trong digu kien Viet Nam
Qua cap nhat thdng tin va nit kinh nghiem tu cac mau may cua nude ngoai ket hgp vdi thuc te san xuat d nude ta, chung tdi da nghien cuu thiet
ke che tao, thu nghiem va trien khai ung dung mau may say tang sdi nang suat 3000kg/h trong dieu kien Viet Nam May say hoat ddng cung d p tten phuang phap gia Idng vat lieu hat bang tac nhan khi de say khd cac hat ran trong ldp hat sdi ddng thdi tao ra ddng chay cua hat vat lieu theo hudng tii vi tri dua vat lieu sdy vao budng say tinh tien dan ra khdi budng say tai vi tri ciia ra cua budng say ket hgp trao ddi nhiet May say loai nay cd hinh khdi chii nhat, ket cau budng dang vdm (hinh nam) da dugc nghien ciiu thiet ke va dua vao san xuat trong thuc tidn (hinh 3)
2014
Trang 8NGHIEN cuu-TRAODOI
1) Ghi phan phSi khi;
2) Lap vat lieu soi; 3) Budng sdy 4) Budng Idng 5) dngthodt khi thdi
Hinh 3: Mdy sdy mudi tinh tdng sdi ndng sudt 3000kg/h duac tac gid
thiet ke che tao vd dua vdo sdn xudt
Mot so dac diem cua may say tang soi lien
tuc dS dirgrc
+ Kha nfing trao ddi nhiet, trao ddi am trong
budng say cao;
+ Thich hgp trong say cac loai hat vat lieu hat
cd am be mat;
-1- Dd dang tu dgng hda tir khau nap lieu den
khau dua san pham ra ngoai;
i- Cd t h i k i t hgp vua say Idid viia lam mat hat
ngay trong mot budng sdy (bd tri lam lam ngudi
hat) d giai doan cudi ciia qua trinh say;
i- Nang suat say cao;
+ Chi phi sdy cho 1 kg san pham sdy thap
han so vdi say dang me
4 KET LUAN VA THAO LUAN
4 1 K l t I u a n
Trong qua trinh tim hidu, nghien ciiu ly
thuydt cung nhu chd tao thidt bi, tac gia [2] da
chii y cap nhat thdng tin, k6 thiia va van dung
TAP
sang tao nhftng kinh nghiem ciia cac tac gia di trudc trong hoan canh cu the cua Viet Nam [2] Phuang phap gia Idng de say khd cac hat ran trong ldp hat sdi da dupe thii nghiem tinh toan, thilt k l md hinh say hat mudi tinh nang suat 48kg/ gid Tir kit qua nghien ciiu ly thuyet va thuc nghiem tren md hinh, tac gia da che tao va chuyen giao 03 the he may say mudi tinh tang sdi dang cdng nghiep vdi nang suat lOOOkg/gid; 1500kg/gid va 3000 kg/gid (xem [3]), cho chdt lugng hat say tdt hon han cac phuang phap say mudi tinh trudc dd bfing may say thimg quay va may sdy rung tang sdi, tiet kiem siic lao ddng, tiet kiem nhien lieu,
May say (hinh 3) dua tren phuang phap gia Idng cac hat say trong ddng tac nhan khi ndng de say khd cac hat ran tren tang sdi bang trao ddi nhiet ket hgp tao ddng hat chay lien tuc Budng say hat dugc tac gia thiet ke hinh khdi chG nhat ket cau hinh nam cho phep hat say vua sdi de thuc hien trao ddi nhiet va trao ddi am vdi cudng
dp cao, nhung lai vira dich chuyen de tao ddng
hat say vao, ra Hen tuc Do ket cdu ty le kich '
CHi CO KHi VIET NAM, So 3 nam 2014
Trang 9NGHIEN cuu-TRAODOI
thudc chilu dai va kich thudc rdng cua budng
say dang khe hep nen thdi gian luu hat trong
budng say rdt ngan, van de xay ra va dap va va
cham giiia cac hat it ban, lam cho cac hat say gan
nhu giir nguyen dupe hinh dang ban dau trudc
khi dua vao say Viec tao Idp hat sdi de dang,
vira ket hgp qua trinh say hat, viia dich chuyen
hat tinh tien, vua lam ngudi ket hgp vdi say nen
san pham say sau khi ra khdi budng say cd the
thuc hien ddng gdi bao quan (nhd hon 70 "C)
Do kha nang nap nguyen lieu vao budng lien tuc
va ra lien tuc nen nang suat ciia may say nay
cao hon han may say dang me trudc day cua tac
gia [1] (dang tru - hinh 2) Chat lupng san pham
say khdng bi bien ddi va gia thanh san pham khi
dua vao san xuat d quy md cdng nghiep da dugc
chap nhan
4.2 Thao luan
Mot van de nay sinh trong qua trinh gia long
va say cac hat ran trong ldp hat sdi se gap phai,
dd la: Su tich tu cac hat ran, cac hat vat lieu khi
gap nhiet se ket lai, dinh vao nhau (vi du nhu la
cac bdt dinh cdn luu lai trong thudc vien, cac hat
vat lieu khd tach rdi nhau, cd dp kit dinh cao,
nhu mudi an cd dp am cao) Su kit dinh nay din
tdi qua trinh truyen nhiet giiia khi cd nhiet dp
cao vdi nguyen lieu lam cham qua trinh gia Idng
cac hat rfin, ldp sdi se it hgt khi - trang thai giiip
cac hat rfin tach dm nhanh va cac thanh phdn
khac kem theo nen tieu tdn nhilu nang lugng
nhiet, anh hudng din chdt lugng va gia thanh
san pham
Tinh chat cua cac hat trong mot dudng dng
cd ddng khi thdi len cdn them ylu td anh hudng
bdi thuc te la van dl phan phdi van tdc khi
cat ngang tiet dien dng se d dang parabol, nlu
TAP CHi CO KHi VIET NAM, S6 3 nam
ddng khi d chi do chay tdng, do vay, mot h^t hay chiim hat se hi Idi cudn trong ddng khi ho|c khdng phu thudc vao vi tri hudng kinh cua no trong dng dan Trong trudng hgp ddng khi d che
do chay rdi, su bien thien ciia van tdc mot each ngau nhien lam cho tinh chat hat lieu hoat ddng them khd du doan
Nhu vay, dieu kien thuc tien thuc nghi6m ciing nhu san xuat ddi hdi phai tach cac hat ran bang cdng nghe, bang ky thuat say va cd "Sir dung ldp dem khd trp sdi trong phuang phap gia Idng de say cac hat ran cd dac tinh ket dinh tren ldp sdi" Cac van de nay se dugc giai quyet trong mot nghien cuu khac, nhung ve mat ky thuat san xuat thi da cd the chuyen giao cho cac ling dung thuc te
5 LOfI CAM ON
Vi nhu cau tieu thu san pham mudi tinh cao cap cho sinh boat hang ngay va dac biet cho cac nha may che bien thuc phSm an liln, va nhu cau ling dung vao thuc tien cua cdng nghe sau thu hoach cho nen ndng nghiep nude nha ngay cang tang, nen tac gia da manh dan nghien ciiu, ling dung phuang phap say mudi tinh trong ldp hat sdi cd ket hop chuyen dich ddng hat de cung cap thilt hi cho thuc tl san xudt Chiing tdi cam
an Cdng ty Hda chat Co ban miln Nam la mpt trong sd cac dan vi dau tien ling dung thanh cdng cdng nghe say mudi tinh bang may sdy tdng soi lien tuc Ddng thdi, chiing tdi cung xin giri Idi cam an den nhirng ngudi phan bien va ddng gop nhung y kien quy bau cho bai bao nay Cam on Ban bien tap da nhiet tinh giiip dd dl cd thi ra mat ban doc
2014
Trang 10NGHIEN CirU-TRAO DOI
Ngay nhan bai: 08/02/2014
Ngay phan bien: 16/3/2014
Tai lieu tham Idiao:
[ 1 ] Norman Epstein -, Applications of Liquid - Solid Fluidization - , International Journal of Chemical Reactor
Engineering, Vol 1 (2003), pp 1-18
[2] Biii Trung Thanh, Trgng thdi soi bot trong khi sdy mudi tinh bang phuong phap sdy tdng sdi lien tuc Tap
chi Co khi Viet Nam, sd 01+02 (2010), trang 65-72
[3] Bui Trung Thanh, Mdy sdy mudi tinh tdng soi lien tuc Tap chi Khoa hoc & Cong nghe nhiet, so 88 (7/2009),
trang 09-13
[4] Tran Van Phii, Nguyen Hay, Bui Trung Thanh, Ddn nhiet vd khuech tdn tdn dm lien hap cua vdt lieu dgng cdu trong cdc thiet bi say ldp sdi Tap chi Khoa hgc & Cong ngh8 nhiSt, so 72 (11/2006), trang 06-08 [5] Bui Trung Thanh, Xdc dinh tdn dp sudt cua tdc nhdn khi qua lap hgt mudi tinh trong qud trinh sdy bdng mdy sdy tdng sdi lien tuc Tap chi Co khi Viet Nam, so 149 (12/2009), trang 16-22
[6] Biii Trung Thanh, Xdc djnh mot sd thdng sd vdt ly co bdn ciia hgt mudi tinh de img dung trong linh toan thiet
ki sdy bdng mdy say tdng sdi hen mc Tap chi Co khi Viet Nam, so 146 (9/2009), trang 13-16
[7] Biii Tmng Thanh, Xdc dinh van tdc khi qua lap hgt soi tdi thieu tren md hinh mdy sdy mudi tinh tdng sdi lien tuc Tap chi Ca khi Viet Nam, s6 145 (11/2009), trang 14-17
[8] Botterill J S., Fluid-Bed Heat Transfer: Gas - Fluidized Bed Behaviour and its Influence on Bed therminal Properties New York Academic Press, Hardcover, USA, 1982
[9] Fan L.T, Wang S.C, Wen C.Y and Roy G.K., Prediction of pressure drop across a gass-solid semi- fluidized bed Ind Chemical Electronic Journal, vol 57 pt CH3, June 1977, India
[10] Howard.J.R Fluidized bed Technology, principles and application, Publisher Taylor & Francis Group Date,
1989
TAP CHi CO KHi VIET NAM, So 3 nam 2014