Giáo trình kỹ thuật sấy nông sản thực phẩm

NlIA XUAT BAN KHOA HOC VA KY THUAT

HA NQl

(In /lin tM hai)

GIAo TRINH

KYTHUATSAY •

A? K

NONG SAN THUC PHAM •

002.27

KHKT - 04 469 - 133- 04

3

Tac gid

-

K.f lhuql .vo.,. nong sail - tlurc phdm hi mon /U!C quail trong nta

sinh vien lIgOlI1! May \'(1 thiet hi cong nghf tlu«: phdm, cong IIghf sinh

hoc, Ngoai ra ,,6 COil lei leli lifll tham khdo trong hoc r.~ip,gidng dav;

nghien CUlt khoa hoc eua cac nganh co liell quail dell ky thU{lt say. N6

ding rat call cho nhiing ngLfili nghien cuu lhift kt, eM'I{lO, ldp dijl,

vdn hanh V£1slfa chiia cac loai may say.

N¢; dung giiio trinh de' cap day dli \'0 still stic !_v thuyer so_v noi

chang \.'(1 ky thua: so_v 110l1g san lh~(c phdm noi rieng. Sail phdn If

thuy{t ia cdc h~ thong say duac de cdp rat phong phU do dang. N6 con

dua ra nl1l1118cdu tao cu lhl cua cac 10(1; tti say..budng say, ham say,

IJl£lp say, may say bang tdi, may sti}'phun, \..\...., cung nhiing 1lIL,nhuoc

dilm eua m6i loai. \'" l'cJ), 116cling giup ich clio nhiing Ilho dall tu, kinli

doanh lua chon va sa dung t6t cac loai may say hi~n co tren thuang

truang.

Mq,c di: r6.t c6 gang trong bien. soon. giao trinh. nay, nhung

cung kh() tranh. khOi nhftng thilu sot, mong d~ gid. xa gan gop j

tU nhang l12n tai ban duC/C t6t han.

LC}I NOr DAU

5

32

32

34

37

9

9

9

11

12

14

15

15

16

18

18

21

'23

27

1.1. vu lieu am

1.1.1. KMi niem chung

1.1.2. D~c tfnh va phan loai cac d6i nrong s4'y

1.1.3. Nhiing d~e tfnh cau true cua d6i nrong s4'y

1.1.4. Cac dang lien k€t giila nuoc va v~t lieu

1.1.4.1. Lien kt't hoa hQC

1.1.4.2. Lien kt't hoa 19

1.1.4.3. Lien k~t eo 19

1.2. Khong khf :tm va kh6i 10

1.2.1 Khong khf Am

1.2.2. D6 thi i - d va trang thai cua khong khf Am

1.2.3. KhI10 d6t (kh6i 10)

1.3. H~ can bang giiia v~t lieu Am vAkhf am

Chl(ung II. cAc QuA TRiNHTRuyiN Nm~T

'VAAMKmSAY

2.1. Quan M giua nhiet va truyen am

2.2. Cac giai doan s~y

2.3. Cae dttbng cong s~y va t6c dOs4'y

LOi n6i dau

Chuong I. V~T LltU AM, KH6NG KHI AM " ..... ,. ~

VA H~ CAN BANG

MVC LVC

6

4.1. D~e tinh chung va phan loai cac h¢ thong say d6i luu 55

4.1.1. Che d¢ HUll viec cua ht; thong say d6i lUU 55

4.1.2. Dang vat say 56

4.1.3. CAneU'vao ap suat trong buong siy 56

4. 1.4. Theo each nung n6ng khong khf thanh tac nhan say 57

4.1.5. CAncO-vao chuyen dong ciia tac nhan say 57

4.1.6. CAncO-theo so do Iam viec 58

4.1.7. CAn eO-vao .eau true buong say 58

4.2. Tfnh toan Mth6ng say d6i luu 58

4.2.1. Phuong phap tao dung h~ thong say 58

4.2.2. Tinh hrong Am bay hoi 59

4.2.3. Xac djnh cac kfch thtroc C(J ban cua bu6ng say 61

4.2.4. Tfnh lueng khong khi e~ cho say 63

4.2.5. Tinh toan nhi~t h~ th6ng say 64

4.2.6. Tfnh bd sung nhiet btl tOn thl(t 68

4.2.7. Xac dinh hrong tieu hao rieng cua khOngkillva nhiet

khi say 72

4.2.8. Cac so' d61am viec cua h~ th6ng slfyd6i hru 77

4.2.8.1. H~ th6ng tuan hoan mot phltn tac nhan siy 78

4.2.8.2. H¢ thong tu~ hoan toan b¢ me nhan siy . 84

2.4. Then gian slfy 46

Chll(YflgIll. C(>NG NGH~ SAY 48

3.1. Nhung tinh chlft cong ngh~ cua cac san pham thuc ph!lmHi

d6i tuong slfy 48

3.2. Lira chon phuong phap va che d<>say 52

Chuong IV. SAY n6I LUU 54

7

4.2.8.3. H~ thong c6 d6t nong b6 sung cho lac nhan siCy 86

4.2.8.4. H~ th6ng c6 d6t n6ng b6 sung v~tuan hoan mQt

ph~ tac nhan s«'y 90

4.2.8.5. H~ th6ng say dieu chinh nang su«'t nhi~t eUa

tac nhan s~y 92

4.3. Cac y~u t6 Anh hul:mg de'ncuOng dQs«'y 94

4.3.1. Anh huOng cua nhi~t dQlac nhan s~y 95

4.3.2. Anh huang cua dQam nrong doi clla tac nhan say 96

4.3.3. AM huang ella t6c dQlac nhan s~y 96

4.3.4. Anh huang cua cac thOng s6 che' dQsay d!!nham am

hlc k!!tthtic giai doan thll'nM't 97

U~~~~~~~~~ ~

4.4.1. Nhiing quy lu~t doi vm say d6i hnr v$t li~u roi xep ICIp 99

4.4.2. Bu6ng s«'y 102

4.4.3. Hhn s«y 109

4.4.3.1. H4m sa:y c6 xe goong 109

4.4.3.2. H4m sS:ye6 xe treo 112

4.4.3.3. May say bang 1& 114

4.4.4. 'IMp s~y 122

4.4.5. May s~y thUngquay 132

4.5. Say d6i luu etc v~t lieu rm leu dQng 139

4.5.1. ac dinh luq,t v~ luu d¢ng t4ng soi va phut 139

4.5.1.1. DQngluc hQCv~ sue can dQngluc ella t~g sOi

vAphut 140

4.5.1.2. OlUy6t kh6i va truyen nhiet vm t4ng soi va

phut (sOi tu4n hoan) 145

4.5.2. Cac h~ th6ng va thi& bi .. '.,'':lng sOi 148

8

(say tren be m~t v*t Dong)

5.1. Qua trinh s~y rang 200

5.2. Cac ki~u may s~y rang 202

5.3. Tinh thiet k~ may s~y rang 207

Chl/ung VI. cAc BiNH TUU'C SAY KHAc 213

6~1. Slfy bdc x~ 213

6.1.1. Co cM truyen nhiet va chuyen kh6i trong s~y brrc xa 214

6.1.2. Cac Mth6ng s~y brrc x~ 217

6.1.3. Cac thi~t bi pitat tia bee xa 218

6.1.4. Cac buoc co ban tfnh thUt ke h~ thong s~y btrc xa 219

6.2. ~y thang hoa 221

~h~l~c 227

Chl/Oftg V. SA""Y RANG 200

4.53. Cac dinh lu~t v(ri 16p rung 1S5

4.5.4. May sA'ylap sOi rung 161

4.6. Slfy d6i hru v~t Ji~u rOi hoac dung dich theo dong luu dQng 165

4.6.1. Cac dinh lu~t ve dong hru dong 165

4.6.1.1. Cac d~e tinh cua dong hru dong 165

4.6.1.2. TImy d()ng hoc va sue can v6i dong luu d()ng 169

4.6.1.3. Truyen nhiet va chuyen kh6i vrn dong hru d()ng 178

4.6.2. H~ th6ng slfy dong hru d~ng dang 60g, xyclon, xoay 16c 182

4.6.3. Cac h¢ th6ng slfy phun 188

4.6.3.1. Phuong phap va C(J c~u phun 189

4.6.3.2. Bu6ng va co eht s~y phun 192

4.6.3.3. Tfnh thi~t ke buong say phun 195

9

(I -2)

Inn 100 C1 \1'=- ,7G

III

D¢ chua ~m II cua v~t lieu IAty so giua mn va 1110:

m; - kh6i luong cua Am (nuoc), kg;

nI" - khoi hrong cua chat kho, kg;

III - khoi hrong cua V~l lieu !{m, kg.

D¢ [lm tfnh theo cong thirc (1-1) III dai luong khong thu nguyen.

Neu tfnh thee phan tram thi ta dung cong thric (1-2) sau day: "

11In I1ln

\I' =-=

111 f11o+m

1.1.1. Khal niem chung

Trong v~t lieu Am gom c6 v~t ran, cMt long va khf. VI khoi

hrong cua chat khf rat nho (m~c dil n6 chiem dung"tfch Ian trong v~t

am) c6 th~ bO qua, nen v~t Am diroc xern nhu g6m hai thanh phan la

chat rAn va chat lOng tha'm uOt (goi la am).

Olar rl\n goi la v~t chat khO tuyet d6i .

D¢ am cua v~t lieu diroc Icy hieu la 11'

1.1. V~T LI~l' A~I

V~t lieu ftm,

khong khi ftm va he can bang

CI,,((rng1

Hlnh 1 -1. Quan h~ giila rIg em va d¢

ehila am eua v~t li~u

().2

0,8

1,0

1.2

1,4

10

V~t lieu bi say la v~t lieu

am da bi tach mot pMn hay

toan b¢ luong am. Thong

thucng vat lieu am duqc say

den de? am phu hop nao do chu

khong say d€n mire chi con

chllt kho tuyet doi.

D6i nrong say lit v~t lieu

~ dang say hay se say.

Tac nhan say la chat khi

hoac long tao thanh moi

tnrong boc lay .d6i nrong say,

d~ Am tach khoi d6i tuong say

va di theo no. Nhiet d9. dQ 11m

va toe de? cua tac nhan s1fy anh

hllemg ion den qua trinh say.

Quan h~ giiIa w va 1I duoc the hien a hlnh I - I:

Tfch s6 gifra khoi Iirong rieng Po cua char kho va de? chua am II

goi ia mat de? am eva duqctfnh thea cong thue sau:

C = Poll (1-6)

(1-5)

(1-4)

(1-3)

H.' II

11=-- va \\'=--

1- II' 1+"

Tir cac quan he tren ta CO:

'.' III

1I=_D x 100,%.

1110

boac:

IIln 1;1-1110 III,)

II= - = = _ __:..:_-

1110 III" =:»,

I 1

1.1.2. f)~c tinh va phan lo~i cac doi urong say

Theo quan lli6m hoa 19, v~t <lmla m~ h~ lien k~ phfm tan giua

pha phan tan va mol tnrong phan tan. Pha phan tan 18.mql ~hal c6 cau

true mang hay khung khong gian tU chill ran phan deu trong moi

tnrong phan tan (ia mot cMt khac).

H~ phan (lin dugc chia Jam ba nhorn: phan tan tho, ken va phan

ur (ion).

Trong he philo Ian the), cac phan tlf co kich Ihu(1l; hm hem 1O-1m.

Trong h¢ nilY gl)m co huyen phu va nhii tU(1Og, chung khong ben virng

nen de dang phan lap.

H~ kco duoc xac dinh bCri cac phan nr co kich thu6'c lu 10 9 den

10""m, Do cac phan tli ella pha phan tan 1an hem ella rnoi tnrong phan

tan nen h~p phu cac phan tli cua moi tnrong phan tan len be m~t cua

cac pMn til cua pha phan Ian.

H~ phan tan phan tit ho~c ion co kich thuoc nh6 hem 10-9 m. DAy

thuc chat 18.h~ phan tan ella cac phan tir hay ion. H~ nay r~l ben vtrng.

Keo la ml)t dang ella h~ phan tan phan tiro V6i keo thl cac phan

Iiicua pha phan tan khong chuyen dich HI do nhir trong dung dich rna

lien ket voi nhau. Cac phan til cua rnoi rnrong phan tan choan day

khong gian giua cac pMn ill ella pha phan tan.

Keo eo ngu6n g6c hfru co hay vO co, t\! nhien hay nhan tao, dan

h6i hoac khong dim Mi. Keo khong dan hOi hut ehtt long th!l!n uO't no.

Khi hut hay nha rurcc, keo khong dan hoi hAu nhir khong {hay d6i

dung tfch.

Keo dan hoi chi hUt mot s6 chat long, khi d6 dung tich cua no

gia tang va va ra, tan fa thanh dung dich. Qua trmh nay phu Ihu9C vao

nhieu yeu t6 nhu cuong dO tan phan tan ciia pha, nhiet d(>,ap su~t cua

rnoi tNang v. v.

Til nhirng d~c tinh tren nguoi ta chia nhirng v~t ran lim thanh ba

12

trong do:

\' L - the tich cua cac 16 xop, rrr';

\' K - the tich cua cac phan tir cau tao khung v~t chat kho, m";

P, Pm - kh6i Iuong rieng cua V~l xop, v~t ehll't (cac phan llr) cau

t~o khung, kg/rrr'. .

(1-7)

\' l'-\' P

s: =i = __ 1: = 1--

\ \' v Pm

1.1.3. Nhfrng d~c tinh cau true cua doi tuong say

Ph1n Ian cac vat lieu fun co cau true xop. Khoang each giiia cac

phdn t\r cau tao nen khung V~I chat khft Ian hon kich thtr6c cua phan

tir. Khong gian gitra cac phan tll goi Iii cac mao dAn hay cac 10 xop.

D6i VOl v~t lieu Am thl cac mao dan hay 10 xop chua diiy mroc. Lire

lien kel gitra be m~1 cua cac mao dan va 10 x6p v(1i mrdc cung vc'ri

tnrong hap dan xac dinh trang thai cua chat long trong v~t ~m.

Call tnic khong gian cua cac mao da.n hay 16 x6p fal phuc rap.

Tfnh chfit cua chung duqc xac dinh bOi hang Ioat d~c tfnh cau tao cua

v~t x6p. Nhtmg d~e tinh do la d~' x6p, de} rham tMu. dang va kieh

thuoc cua cac 16 xop.

Do x6p cua V~l the la Cf' duqe de dinh theo cong thuc (1-7)

dum day:

nhorn: ken, x6p mao dan va kco - x6p mao dan.

Trong nhom kco thl loai dan h(~i se thay <l6i th~ tfch (giam di)

khi say nhirng vAn gifT du9"Ctfnh dan hOi.

Trang nhorn xop mao cHn la kco khong dan hoi , sau khi say no

vo VI:1n fa va co the thanh ht)t. .

Nhom kco - x6p mao dan co tfnh chat cua ca hai nhom trcn.

Khi hut mroc no rnrong va ra, khi' say no co Iai va phan l{m va vun ra.

Cac dCiinreng say trong cong nghiep thuc ph~m co cau true ral

phuc rap. Vi vay vm each chia nhom nhu tren (theo A.V.Likov) In

chua thoa dang dve thuc lien va Iy thuyet trong khi say.

13

Hinh 1-z. M~t edt cua v~t )(Vp.

1-16 (ranh) bao; 2-ranh CI,lI;3-ranh he,

v~t ~m.

Trong moi truong

phan tan, khong gi an thuc

cfra cac 16 tr6ng duq~

rhay the bang khong gian

giiia cac phan nr htnh cau

co cung durmg kinh.

Chieu dai cua mao dan ho hay ranh ho (hinh 1-2).

2

D9 tham thau cua V~I xop la kha nang cho chat long tharn qua

khi co lac dung cua tnrong ap suat naodo.

Do cau true cua cac mao dan hay 16 xop ra} da dang va It rnang

tlnh quy hl~t nen khong th~ ap dung thuyet giai tfch d~ khao sal

chring. Thay vao J6 ngum ta dung mo hlnh mao dan va rno hlnh phan

Ian dt khao sat cac iinh hU<1ogden rrang thai cua Am trong v~t x6p.

V6i mo hlnh mao

dan, khong gian tht!c cua

cac 16 x6p diroc thay

hang cac ong mao dan co

ciing dUOng kfnh phan b6

deu trong dung tfch cua

t;,=e,=t.·

trong do:

FL - tOng dien tich ella elk 16 xop tren mat elit nao <16qua v~t

xop, rrr';

F - dien t(ch mat dt dIU v~t xop. m.

V6i gia tr! gan dung:

(1-8)

F: .

t.' - J. '-7

Ngoai d¢ x6p e, con co d~ x6p b~ m~t l>., duoc xac dinh theo

. cong thuc (I· 8) sau:

14

Niroc co trong vat lieu am co Ihci chia lam hai nh6m: mroc II! do

va rnroc lien ket.

Nuoc nr do nam (J be mat ella vat, co ap sua! rieng bang ap suA'!

hoi nuoc bao hoa ling voi nhiet d<)hien tai ella V~I llm.

Nltac tv do nam trong v~t am Iii luong nuoc tao ra tren be mat

ella v~t Am hoi nude co ap suat rieng dat gia tri bao hoa 6 nhiet dO hien

l;,ti cua V~I ~m.

Nuoc lien ket 11;\0 ra trcn v~t am hoi mroc c6 ;ip su~t rieng nho

han ap SUal baa hoa ling vOi nhiet dQ cua v~t.

Do khd nang phan irng hoa hoc va hoa tan manh cac chA"tnen

trong cac san ph5m thirc phfun khong 0.::6mroc nguyen chat rna dum

dang dung dich.

Muon tach nuoc rakhoi vat ;lm dn co o[m~lmmg bang hay Ian

hem nang lirong lien kct cua no vOi vat elm. De c6 thIS lua chon phuong

1.1.4. Cac dang lien ket giiia mroc va v~t Ii~u

Trang d(l:

IL - chieu dai cua mao d~n;

b - chieu day vat xop (chieu day hlp loc).

Thong thLloog ;K C(l gia Ir~trong khoang 1,13 den 17.5.

Doi v(ji v~t x6p hlnh thanh ttr viec dO thanh lop cac phan ttr nho

(vat lieu roi xep lap) co hlnh dang bllt ky thi h~ s6 khilc khuyu co cac

gia tri q", tu 1den 1,47 voi e ttr 0,84 den 0,36.

bao gio cling Ian hem chieu day ella vat xop. Ty s6 giua chieu dai cua

mao dan ha rren chieu dai ella vat x6p theo chieu tham (hau (chien loc)

ella v~t x6p goi Ill.h~ so khuc khuyu ~\:

I

e - __!_:_ (1-9).

• K - h

15

t

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c

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vci ca

c

hi¢

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t

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m

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t gioi han

c

a

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h

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l

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han tu

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n nam

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phia 13 bAn

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p

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(

1

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6

t nhal, can p

hai

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ng lien

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6 vm

V~l

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