Tinh Toan Lap Dat Kho Bao Quan Dong Suc Chua 400 Tan

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LI CM N

Trc ht em xin chn thnh cm n cc thy ngnh Nhit Lnh truyn

t nhng kin thc, kinh nghim qu bu cho em ni ring v cc bn trong lp

ni chung, trang b cho em nhng kin thc trc khi bc vo i . N s l

nn tng vng chc cho nhng bc pht trin ca em trong s nghip cng

nh trong cuc sng , em xin ghi nh cng n ny.

Nhn y em xin by t lng bit n su sc nht ca em n Ban Gim

c Cng Ty, cc c ch, anh, ch tt c Phng Ban ca Cng Ty TNHH T

Vn K Thut Cng Ngh Tn Tin, gip v to iu kin thun li, tn

tnh ch dn trong sut qu trnh thc tp ti Cng Ty , khng ch v mt kin

thc chuyn mn m c v kin thc x hi rt b ch cho ngh nghip tng lai

sau ny. V c bit thy Khng Trung Thng tn tnh hng dn em hon

thnh cun n tt nghip ny.


MC LC

MC LC......................................................................................................1

LI CM N ..................................................................................................4

LI NI U .................................................................................... ............5

CHNG 1 : LUN CHNG KINH T - K THUT................. ............6

1.1. S cn thit ra i nh my ch bin thu sn xut khu ti Cn Th........6

1.2. Cc yu cu v kinh t v k thut ....................................................7

CHNG 2: TNH TON MT BNG KHO LNH ................................9

2.1. KHO ST S MT BNG LP T KHO LNH. ............9

2.1.1. Chn a im xy dng kho lnh................................................9

2.1.2. Cc thng s kh hu ...................................................................9

2.1.3. Cc iu kin bo qun trong kho. ...............................................9

2.2. TNH KCH THC KHO LNH...................................................10

2.2.1. Dung tch kho lnh. ......................................................................10

2.2.2. Din tch cha sn phm kho .......................................................11

2.2.3. Ti trng ca nn v trn. .............................................................11

2.2.4. Din tch cn xy dng. ................................................................11

2.3. TNH CCH NHIT CCH M......................................................12

2.3.1. Vt liu cch nhit, cch m.........................................................12

2.3.2. cu trc kho lnh...........................................................................13

2.3.3. Tnh ton cch nhit cch m cho kho lnh .................................14

2.4. CU TRC KHO LNH. .................................................................17

2.4.1. Cu trc nn kho lnh...................................................................18

2.4.2. Cu trc vch v trn kho. ............................................................18

2.4.3. Cu trc mi kho...........................................................................18

2.4.4. Ca kho.........................................................................................19

CHNG 3: TNH TON NHIT TI V CHN H THNG ...............20

3.1. TNH NHIT TI..............................................................................20


3.1.1. Mc ch. ......................................................................................20

3.1.2. Tnh nhit ti.................................................................................20

3.1.3. Xc nh ti nhit v nng sut lnh cho my nn. ......................26

3.2. CHN CC CH LM VIC V TNH CHN THIT B. ...27

3.2.1. Chn cc ch lm vic .............................................................27

3.2.2. Tnh chu trnh my lnh................................................................31

3.2.3. Tnh chn thit b..........................................................................35

1. Chn cm my nn dn ngng.................................................35

2. Chn dn lnh. .........................................................................36

3. Tnh chn cc thit b ph........................................................36

4. Tnh chn ng ng dn mi cht trong h thng. ................43

3.3. B TRI MY V THIT B ............................................................45

CHNG 4: THI CNG LP T .............................................................47

4.1. GIA C V XY DNG NN MNG ..........................................47

4.1.1. c khung kho bng b tng ct thp..........................................47

4.1.2. Dng khung mi v lp mi............................................................... 47

4.2. LP T KHO LNH, ....................................................................47

4.2.1. Cng tc chun b. ........................................................................47

4.2.2. Thi cng lp t. ...........................................................................47

4.3. LP T H THNG LNH..........................................................54

4.3.1. Lp t cm dn ngng, my nn.................................................54

4.3.2. Lp t cm dn lnh....................................................................55

4.3.3. Lp t ng ng ht ca my nn, v ng ng t bnh cha cao p

n dn lnh, bnh tch lng v van tit lu. ...............................56

4.4. UI BI V TH X, HT CHN KHNG V NP GAS H

THNG...........................................................................................................59

4.4.1. Quy trnh ui bi h thng.........................................................59

4.4.2. Th x h thng............................................................................60

4.4.3. Ht chn khng h thng.............................................................60

4.4.4. Np gas cho h thng. .................................................................61


4.5. MCH IN NG LC V IU KHIN CA H THNG..62

4.6. VN HNH H THNG LNH .....................................................65

1. Cng tc chun b. ..................................................................... 65

2. Vn hnh h thng.....................................................................65

3. Dng my. ................................................................................66

4.7. BO DNG H THNG..............................................................67

KT LUN.....................................................................................................69

TI LIU THAM KHO ..............................................................................70


LI NI U

K thut lnh l mt ngnh tuy cn kh mi m nc ta, nhng trong

nhng nm gn y n c pht trin v ng dng rng ri trong mi lnh vc

ca i sng con ngi. c bit l trong ngnh cng nghip ch bin thc phm.

i vi cng nghip ch bin thu sn th yu cu s dng lnh l tt yu, v vy vic

thit k h thng lnh hot ng hiu qu l yu cu cp thit i vi cc nh my ch

bin thy sn.

c s phn cng nh trng, khoa ch bin v b mn k thut lnh ti

thc hin n tt nghip: Thit k v lp t kho bo qun ng sc cha 400

tn vi cc ni dung dung chnh nh sau:

Chng 1: Lun chng kinh t k thut.

Chng 2: Tnh ton mt bng kho lnh.

Chng 3:Tnh ton nhit ti v chon h thng.

Chng 4: Thi cng v lp t kho lnh.

Chng 5: Kt lun

Trong qu trnh thc hin n ti c c gng, nhng kinh nghim v kin

thc c hn nn chc chn s khng trnh khi nhng sai st nht nh. Knh mong s

ch dn ca qy thy c.

Sinh vin thc hin.

inh Trung nh


CHNG 1 : LUN CHNG KINH T - K THUT

1.1. S cn thit ra i nh my ch bin thu sn xut khu ti Cn Th

Khi quyt nh xy dng mt nh my ch bin thu sn ngi ta phi cn c vo

nhiu kh nng, nh kh nng u vo ca ngun nguyn liu v u ra ca sn phm,

kh nng v mt bng xy dng ca nh my, kh nng v giao thng, ng x, in

nc, v lc lng lao ng v gii quyt vic lm cho ngi lao ng, v cui cng

l kh nng v vn u t xy dng nh my.

S cn thit xy dng nh my ch bin thu sn Thin M xut pht t nhiu yu t:

Th nht l xut pht t kh nng cung cp ngun nguyn liu cho qu trnh ch

bin, nh my ch bin thu sn Thin M xy dng ti Cn Th s c cung cp

ngun nguyn liu t ni tnh v cc tnh ln cn. S ra i nh my ch bin thu sn

ngi ta quan tm th nht l ngun nguyn liu cung cp cho qu trnh ch bin, c

nguyn liu th nh my mi hot ng n nh lu di v c li nhun. Ngun

nguyn liu c tra - c basa c nui rt nhiu cc tnh min Ty Nam b, theo cc

s liu thng k hng nm th sn lng v din tch nui trng c tra v c basa cc

tnh Ty Nam b khng ngng tng ln hng nm, v vy kh nng nguyn liu cung

cp cho qu trnh ch bin, khng nhng th y kh hu quanh nm n nh c

th nui c quanh nm c, nn ngun nguyn liu dp ng c quanh nm.

Th hai l xut pht t th trng tiu th, hay u ra ca sn phm ln n nh

my, n quyt nh n vic tn ti v pht trin ca nh my. Cng vi s pht trin

ca ngnh thu sn ni chung v ngnh cng nghip ch bin thu sn ni ring th

trng tiu th ca cc sn phm ch bin t thu sn ang ngy cng c m rng

c trong nc v ngoi th gii. Cc sn phm ny xm nhp vo cc th trng kh

tnh nht ca th gii v c chp nhn v c nh gi cao, nh th trng EU,

Nht, M Mun xm nhp vo cc th trng ny th cht lng sn phm phi c

gi tr v cht lng cao m bo c yu cu v v sinh an ton thc phm . Vn

ny lin quan n cng ngh, v trang thit b phc v cho qu trnh ch bin.


Th ba l xut pht t kh nng gii quyt vic lm cho lao ng, nh my ch

bin thu sn cn rt nhiu cng nhn phc v cho qu trnh ch bin. Min Ty Nam

b c ngun lao ng di do nn p ng cho nh my ch bin. Trong ngoi

lao ng cung cp t ni tnh cn c rt nhiu lao ng n t cc tnh ln cn. Nh

vy nh my ch thu sn ny gii quyt khng t vic lm cho ngi lao ng, v

y ngun lao ng ang b d tha.

Nh vy vi phn tch trn th s ra i ca nh my ch bin thu sn l cn

thit v hp l. N khng nhng thc y ngh nui c a phng v cc tnh ln

cn khc, to vic lm, tng thu nhp cho ngi lao ng.

1.2. Cc yu cu v kinh t v k thut.

S ra i ca nh my ch bin thu sn lun km theo nhng yu cu c tnh

bt buc, c lin quan n kh nng hot ng v pht trin ca nh my, cc yu cu

nh: giao thng, in, nc, ngun nhn cng Khi xy dng nh my th ta phi

xem xt kh nng p ng ca chng n u.

1. Yu cu v v tr xy dng v c im thin nhin.

Yu cu v mt bng xy dng nh my ch bin thu sn phi tng i ln, th

nht nh my ch bin thu sn Thin M nm khu cng nghip Tr Nc nn n cch

xa khu dn c trnh nh hng n khu dn c nh n v nhim Th hai l a

im xy dng phi tng i thun li v giao thng, cp in v cp thot nc.

2. Yu cu v giao thng, in , nc, nhn cng

Yu cu v giao thng, thng thng c hai loi hnh chnh l giao thng ng

thy v giao thng ng b, ti Cn Th giao thng ng thy ch yu l ng

sng, ng b th tng i thun li. Khu cng nghip Tr Nc nm thnh ph

Cn Th nn gn dng sng Hu nn rt thun tin cho vic lun chuyn giao thng

ng thu, khng nhng th m giao thng ng b cng rt thun li. V vy vn

giao thng ng b lun chuyn cng tng i thun li.

Yu cu v in, nc, i vi nh my ch bin thy sn vn in v nc l

hai yu t quan trng nht v khng th thiu, v kh nng p ng th hai yu t ny

u thun li. Do khu cng nghip ny gn trm cung cp in cho ton thnh ph


nn vn in l rt thun li. Cn vn nc th dng ngun cung cp nc ca

thnh ph nn yu t ny cng khng phi bn tm.

Yu cu v nhn cng, v nhn cng c hai dng l nhn cng k thut v lao

ng ph thng, nhn cng k thut c o to trng lp, yu cu c chuyn

mn cao c cung cp t cc trng i hc nh Thy Sn, Nng Lm. Nh phn

tch trn th ngun lao ng ph thng di do, c cung cp t trong thnh ph v

cc tnh ln cn. Nh vy yu cu v ngun nhn cng p ng c.


CHNG 2: TNH TON MT BNG KHO LNH

2.1. KHO ST S MT BNG LP T KHO LNH.

2.1.1. Chn a im xy dng kho lnh.

Chn a im kho lnh l cng tc khng th thiu v ng vai tr quan trng

trong qu trnh thit k v xy dng kho. Khi chn a im th ta phi bit c cc

thng s v kh tng thu vn, a l T ra cc phng n thit k v xy

dng kho cho thch hp lm cho cng trnh c gi thnh thp nht v cht lng

cng trnh l tt nht, cng trnh c cc ri ro do thin tai gy ra nh thin tai, l

lt ti a phng xy dng kho.

Nh my ch bin thu sn Thin M nm trong khu cng nghip Tr Nc

Thnh ph Cn Th nn khi chn a im xy dng nh vy m bo cc yu

cu trn .

2.1.2. Cc thng s kh hu

Cc thng s kh hu ny c thng k, khi tnh ton m bo an ton th ta

phi ly gi tr cao nht, tc l gi tr khc nghit nht m bo an ton cho my

lnh v trnh cc s c ng tic xy ra. Tra bng 1-1 sch HDTKHTL ta c.

Bng 2-1. Thng s kh hu Cn Th.

Nhit , 0C m tng i, %

TB c nm Ma h Ma ng Ma h Ma ng

26,7 37,3 17,4 78 82

2.1.3. Cc iu kin bo qun trong kho.

Ch bo qun sn phm trong kho cng chnh l iu kin mi trng trong

kho m ta phi to ra duy tr sn phm t tiu chun cht lng cao.


a. Chn nhit bo qun.

Nhit bo qun thc phm ph thuc vo tng loi sn phm v thi gian bo

qun ca chng. Thi gian bo qun cng lu i hi nhit bo qun cng thp.

nh my ch bin thu sn Thin M ch yu ch bin mt hng c tra c

basa ng lnh nn thi gian bo qun thng t hn 10 thng nn chn nhit bo

qun l 200C.

b. m ca khng kh trong kho lnh.

m ca khng kh trong kho nh hng rt ln n cht lng sn phm khi

s dng. Bi v m ca khng kh trong kho lin quan n hin tng thng hoa

ca nc trong sn phm. V vy tu tng loi sn phm m ta chn m ca

khng kh cho thch hp.

Sn phm ca nh my ch bin ra u c bao gi bng nha polyetylen v ba

cctong nn ta chn m khng kh trong kho > 80%.

c. Tc khng kh trong kho lnh.

Khng kh chuyn ng trong kho c tc dng ly i nhit lng ca sn phm

bo qun, nhit do m ca, do cu nhit, do ngi lao ng trong kho. Ngoi ra cn

phi m bo s ng u nhit , m v hn ch nm mc hot ng.

nh my Thin m sn phm c bao gi cch m nn ta thit k khng kh

i lu cng bc bng qut gi vi vn tc v = 3m/s.

2.2. TNH KCH THC KHO LNH.

2.2.1. Dung tch kho lnh.

c xc nh theo cng thc

VV g

EVgVE ==

E : Dung tch kho lnh (tn), dung tch kho lnh cho trc l 400 tn.

V : Th tch kho lnh (m3),

Vg :Tiu chun cht ti (t/m3), i vi hng thu sn ng lnh th

45,0=Vg t/m3


( )389,88845,0

400 mV ==

2.2.2. Din tch cha sn phm kho.

c xc nh qua th tch bung lnh v din tch cht ti

hVF =

Trong :

:F Din tch cha sn phm (m2)

:h chiu cao cht ti (m)

Chiu cao cht ti l chiu cao l hng cht trong kho, chiu cao ny ph thuc

vo bao b ng hng, phng tin bc xp. Chiu cao h tnh bng chiu cao bung

lnh tr i phn lp t dn lnh treo trn v khong khng gian cn thit cht hng

v d hng.

Kho lnh thit k d nh cao 3m v chiu cao cht ti d kin l 2,3m

Vy 247,3863,289,888 m

hVF ===

2.2.3. Ti trng ca nn v trn.

c tnh theo mc cht ti v chiu cao cht ti ca nn v gi treo

( )2. /035,13,245,0. mthgg VF === 2.2.4. Din tch cn xy dng.

L mt bng cn xy dng kho tnh lun cc tr ct v li i , khong cch

gia cc l hng nn din tch cn xy dng lun ln hn din tch cha sn phm v

c xc nh theo cng thc:

Fxd

FF =

Trong :

:F Din tch cht ti.

:xdF Din tch cn xy dng.


:F H s s dng din tch ca kho lnh hay t s gia cht ti v din tch kho lnh cn xy dng. Tra bng ta c 85,0=F .

)(67,45485,047,386 2mFxd ==

Chn tm panel nh sau: Chiu rng panel l 1,2m.

Chiu di panel l 5m.

T )(67,454 2mFxd = Chiu di kho lnh: 31,2m .

Chiu rng kho lanh l: 15m.

Vy din tch thc t cn xy dng l: 2468152,31 mFxd ==

2.3. TNH CCH NHIT CCH M.

2.3.1. Vt liu cch nhit, cch m.

a. Mc ch ca vic cch nhit.

Ngn chn dng nhit xm nhp t bn ngoi c nhit cao hn xm nhp vo

kho lnh. Nhng khi tnh ton ta phi tnh ton sao cho va c tnh kinh t m vn

hot ng tt ( ngha l chiu dy cch nhit va gim chi ph ban u m dng

nhit khng xm nhp c vo kho lnh).

b. Yu cu i vi vt liu cch nhit.

Kh nng dn nhit km ( nh) . khi lng ring nh nh.

Kh nng hp th hi nc km 0 .

bn c hc v bn do cao.

Bn nhit thp v khng gy n mn hoc phn ng vi vt liu tip

xc n .

Khng d chy.

Khng hp th mi v khng gy ra mi l.

Khng to iu kin cho nm mc v VSV pht trin, khng c hi vi

sn phm bo qun v con ngi, hoc khng lm h hi sn phm .


Gia cng d dng.

R tin, d kim.

Trong thc t khng c vt liu no p ng cc yu cu trn. Nn khi chn

vt liu ta chn vt liu no c nhiu u im nht nhng cng u tin vt liu p

ng yu cu k thut v kinh t nht.

Chn vt liu cch nhit l polyurethan v n c u im ln v to m khng

cn gia nhit nn d dng to bt trong cc th tch rng bt k. Chnh v vy n

c dng lm cc tm panel cch nhit nhiu nht vi hiu qu kinh t cao v

cch nhit tt.

c. Mc ch ca vic cch m.

Mc ch cch m l hn ch s xm nhp m vo kho lnh s lm hu hoi

vt liu cch nhit. Do vy s lm tng chi ph vn hnh.

Vic cch m l lp tn bc ngoi tm panel cch nhit. Lp tn ny c sn khi

ta mua tm panel cch nhit.

2.3.2. Cu trc kho lnh.

Kho lnh bo qun l ni lu tr sn phm sau khi cp ng nn cn phi duy tr

nhit thp, m cao. Khng kh bn ngoi c nhit cao, m thp do lun

c s chnh lch nhit v m gia bn trong v bn ngoi kho lnh. V vy cc

dng nhit v dng m lun lun c khuynh hng xm nhp t bn ngoi vo mi

trng phng lnh.

V vy cu trc kho lnh, vt liu cch nhit v cch m cn m bo cc

yu cu sau:

m bo bn vng lu di theo tui th d kin ca cng trnh (chu c ti

trng ca bn thn v ca hng ho bo qun trong kho, v phi chng c m

xm nhp t bn ngoi vo v b mt vch khng ng sng).

Phi m bo cch nhit tt gim chi ph u t cho my lnh v vn hnh.

Phi chng chy n v an ton .

Thun tin cho vic vn chuyn v sp xp hng.

Do cc yu cu trn nn chn kho l kho lnh lp ghp, kt cu xy dng gm 2 phn:


+ Phn chu lc: gm nn mng v cc thanh dm bng thp( thanh dm

dng cc tm panel trn c nh).

+ Phn cch nhit: l cc tm panel cch nhit n c dng lm tng bao

trn v nn kho lnh.

Cu to ca cc tm panel nh hnh 2-1

Cc tm panel ny c b tr sn cc c cu lp vi nhau (cch lp t s c

gii thiu chng 4).

2.3.3. Tnh ton cch nhit cch m cho kho lnh.

a. Tnh ton cch nhit.

Chiu dy cch nhit c tnh t biu thc h s truyn nhit K cho vch

phng nhiu lp.

=

+++= n

i cn

cn

i

ik

1 21

111

=>

++= =

n

i i

icncn k 1 21

111

Trong :

1: L h s to nhit ca mi trng bn ngoi ti vch cch nhit, W/m2K;

2: L h s to nhit ca vch bung lnh v bung lnh, W/m2K;

PU

Lp sn bo v Hnh 2-1. Cu to tm panel


i : L chiu dy ca lp vt liu th i, m; i : L h s dn nhit ca lp vt liu th i, W/mK; cn: L chiu dy ca lp vt liu cch nhit, m; cn : L h s dn nhit ca vt liu cch nhit, W/mK; K: L h s truyn nhit ca vch, W/m2K.

Bng 2-2. Thng s ca cc lp vt liu ca panel tiu chun.

Vt liu Chiu dy

m

H s dn nhit

W/mK

Polyurethan

Tn l

Sn bo v

cn

0,0015

0,0005

0,023

45,36

0,291

Kho bo qun ng c thit k vi ch trong kho l 20 0 C, khng kh c i lu va phi.

Do di nn c thit k thong bng cc con ln nn h s to nhit 1 v h s truyn nhit K c ly bng gi tr so vi trn v vch kho lnh.

Vy ta c: - H s truyn nhit K = 0,21 W/m2K;

- H s to nhit 1 = 23,3 W/m2K;

- H s to nhit 2 = 9 W/m2K.

Ta c b dy cch nhit ca vch, nn, v trn l:

9,1051059,091

291,00005,02

36,450015,02

3,231

21,01023,0 ==

+

+

+=cn mm.

m bo cch nhit tt chn chiu dy lp cch nhit ca tm panel l:

cn = 125 mm. Chiu dy ca tm panel tiu chun l:

mmstCNpanel 4,12825.022.112522 =++=++=


Ta c h s truyn nhit thc l:

1788,0

91

023,0125,0

291,00005,02

36,450015,02

3,231

1=

++

+

+=tK W/m

2K.

b. Tnh kim tra ng sng.

vch khng ng sng th h s truyn nhit thc phi tho mn iu kin

sau: Kt < Ks. an ton th: Kt < 0,95 x Ks.

Ks: L h s truyn nhit ng sng n c xc nh theo biu thc sau:

Ks = 121

1

tttt s

Trong : t1 l nhit khng kh ngoi mi trng t1 = 37,30C;

t2 l nhit khng kh trong kho lnh t2 = -200C ;

ts l nhit im sng ca khng kh ngoi mi trng

T th (h-x) v t1 = 37,30C; = 0,78 ts = 300C

Vy ta c: : ( ) 968,23,23203,37303,37

=

=sK W/m2K.

Xt Kt < 0,95 x Ks 0,1788 < 2,968 x 0,95= 2,82 tho mn Kt lun.

Vi cu trc cch nhit ca kho lnh bng vt liu cch nhit polyurethan c

chiu dy l 125mm th m bo s cch nhit

Nn kho v trn kho c chiu dy lp cch nhit bng chiu dy lp cch nhit ca

vch kho. Bi v trn kho c mi che v nn kho c cc con ln thng gi. Nn h

s truyn nhit ca nn v trn kho uc ly bng h s truyn nhit ca vch kho.

c. Cu trc cch m ca kho.

Cu trc cch m ng vai tr quan trng i vi kho lnh. N c nhim v ngn

chn dng m xm nhp t bn ngoi mi trng vo trong kho lnh qua kt cu bao

che. Nu khng tin hnh cch m cho kt cu bao che th dng m t mi trng bn

ngoi s xm nhp vo cu trc cch nhit theo s chnh lch nhit lm cho hm


m trong cu trc cch nhit tng ln v h s truyn nhit ca cu trc bao che tng

ln thm ch khng cn kh nng cch nhit.

i vi kho lnh lp ghp cu trc cch m l lp tn bc cch m, tn l vt

liu c h s dn m nh gn bng 0 do vic cch m i vi kho lnh l rt an ton

2.4. CU TRC KHO

Hnh 22: S mt bng kho lnh 1. Panel cch nhit.

2. Dn lnh.

3. Ca ln.

4. Ca s.

1: Tm panel cch nhit.

2. Con ln thng gi.

3. Lp btong chu lc.

4. Nn t .

5. Ca nh.

6. Ca ln.

7. Khung mi che.

8. Dn lnh. Hnh 23: S mt ct kho

8

5 6

4 3

2

1

7

4

3

2

1

Hnh lang lnh


2.4.1. Cu trc nn kho lnh :

Lp cch nhit, cch m l cc tm panel tiu chun.

Cc con ln c c bng b tng hn ch r st cho panel nn, trnh hin

tng ci nn.

Lp b tng chu lc.

Lp t .

2.4.2. Cu trc vch v trn kho lnh.

Kho lnh lp ghp c cu trc vch v trn l cc tm panel tiu chun vi cc

thng s sau:

Chiu di ca tm panel l: h = 3m i vi panel vch cn h = 5m i vi

panel nn v trn.

Chiu rng l: r = 1,2m

chu nn: 30 n 40 kg/m3.

H s dn nhit 03,0023,0 = (W/mK).

c lp ghp bng phng php kho cam s trnh by chng 4.

2.4.3. Cu trc mi kho lnh.

Mi kho lnh ang thit k c nhim v bo v cho kho trc nhng bin i ca

thi tit nng ma bo v s lm vic ca cng nhn, che chn cho h thng my

lnh cho nn mi kho lnh phi t cc yu cu sau:

Mi kho lnh phi c nhim v bo m che ma nng tt cho cu trc kho v

h thng lnh.

Hnh 24: S nn kho lnh.

1400

Con ln

Nen at a

Betong san

Panel nen

1270

10

70

1000


Mi kho khng c ng sng, khng c thm nc, dc ca mi kho

t nht phi l 2%. V vy trong thit k ny ti chn mi che bng tn, nng

bng b phn khung bng st.

25000

Khung mai

Ton lp mai

1500

2.4.4. Ca kho. Ca kho lnh lp ghp c cu to nh mt tm panel c bn l t ng, chung

quanh c m kn bng cao su lm tng kn v gim tn tht lnh.

Kho lnh m ti thit k gm 2 ca trong c mt ca chnh c kch thc

1000*1800 v mt ca s c kch thc 600*600. Hai ca ny to thun li cho

vic xut, nhp hng vo v ra khi kho.

Hnh 25: Mi kho lnh


CHNG 3: TNH TON NHIT TI V CHN H THNG

3.1. TNH NHIT TI

3.1.1. Mc ch.

Tnh nhit ti l tnh ton cc dng nhit t mi trng bn ngoi i vo kho

lnh. y chnh l dng nhit m my lnh phi c cng sut thi n tr li

mi trng nng, m bo s chnh lch nhit n nh gia bung lnh v

khng kh bn ngoi.

Mc ch cui cng ca vic tnh ton nhit kho lnh l xc nh nng sut

lnh ca my lnh.

3.1.2. Tnh nhit ti

Nhit ti ca kho xc nh theo cng thc.

321 QQQQ ++=

Trong 1Q : Dng nhit qua kt cu bao che ca bung lnh.

:2Q Dng nhit do sn phm to ra trong qu trnh x l lnh.

:3Q Dng nhit t cc ngun khc khi vn hnh my lnh.

a. Dng nhit qua kt cu bao che Q1.

L dng nhit tn tht qua tng bao, trn v nn kho lnh do s chnh lch

nhit gia mi trng bn ngoi v bn trong kho lnh cng vi dng nhit tn tht

do bc x mt tri qua tng bao v trn.

12111 QQQ +=

Trong :11Q Dng nhit qua tng, trn v nn do chnh lch nhit .

:12Q Dng nhit qua tng, trn do nh hng ca bc x mt tri.

Dng nhit truyn qua vch, trn v nn do chnh lch nhit Q11. Chiu dy ca tm panel tiu chun l:


mmstCNpanel 4,12825.022.112522 =++=++=

Kch thc tnh ton ca kho lnh l:

Chiu di kho lnh L=31,2 m

Chiu rng kho lnh l R=15 0,128 = 14,872 m

Chiu cao ca kho lnh l H=3 0,128 = 2,872 m

Ta c dng nhit truyn qua vch, trn v nn kho lnh l: TNv QQQQ 11111111 ++=

Kho lnh c t trong nh xng nn ta thy vch kho pha Ty Bc v ng

Bc ta coi nh l tip xc vi khng kh ngoi tri. Cn pha ng Nam gip kho bo

qun th 2. Pha Ty Nam gip vi hnh lang lnh.

Nn chnh lch nhit gia trong kho v ngoi vch pha Ty Nam l:

( ) Cttt 02'1 402020 ==+= Chnh lch nhit 2 mt Ty Bc v ng Bc l:

( ) Cttt 021 3,57203,37 ==+= Chnh lch nhit pha ng Nam l:

Cttt 021 02020 ==+=

Chnh lch nhit trn kho l:

( ) Cttt 021 3,67203,47 ==+= Do trn kho chu bc x mt tri chiu vo mi kho lnh lm bng tn nn phn

khng kh pha di mi tn b bc x mt tri nung nng hn nhit bn ngoi tri

khong 100C

Vy dng nhit truyn qua vch, nn, trn l:

tFkQ tTNV =.,11

Trong :

:tk H s truyn nhit thc ca kt cu bao che, xc nh theo chiu dy

cch nhit thc (xc nh chng trc 1788,0=tk W/m2K).


:F Din tch kt cu bao che m2

:t Hiu nhit bn trong v bn ngoi kho lnh 0C

Dng nhit qua vch kho lnh do nh hng ca bc x mt tri. Do kho lnh nm trong phn xng nn c h thng tng bao che chn nn

khng chu nh hng ca bc x mt tri. Do 012 =Q W

Bng 3-1: Bng tnh ton nhit xm nhp qua kt cu bao che Q1

b. Dng nhit do sn phm v bao b to ra.

22212 QQQ += W

Trong :

21Q : Dng nhit do sn phm to ra W

22Q : Dng nhit do bao b to ra W

Dng nhit do sn phm to ra. Ta c:

( ) ( )W360024

10002121

= iiMQ

Hng

K W/m2K

F m2

t 0C

Q1 W

Vch pha Ty Bc 0,1788 89,7 57,3 918,998

Vch phaTy Nam 0,1788 42,71 40 305,48

Vch pha ng Nam 0,1788 89,7 0 0

Vch pha Ty Nam 0,1788 42,72 57,3 437,77

Trn kho 0,1788 461,2 67,3 5549,73

Nn kho 0,1788 461,2 57,3 4725,1

Nhit do bc x mt tri Q12 0

1Q 11937,082


Trong :

21, ii : Entalpi ca sn phm nhit vo kho v nhit bo qun trong

kho Kj/kg.

M: Khi lng hng ho nhp vo kho bo qun trong 1 ngy m. i vi

kho bo qun th 24400%6%6 === EM t/ngy m.

Ch : hng ho bo qun trong kho bo qun c cp ng n nhit bo

qun . Tuy nhin trong thi gian x l nh ng gi, vn chuyn, nhit sn phm

tng ln t nhiu nn i vi sn phm bo qun ng ly nhit vo kho ti tm

sn phm l -170C

Nh vy c tra thuc dng c bo nn (tra bng 4-2 sch Hng dn thit k h

thng lnh) ta c.

81001 =i j/kg (dng phng php ni suy i vi c bo nhit -170C)

01 =i v t2 = -200C

Do

( ) ( ) ( )W2250360024

10000810024360024

10002121 =

=

= iiMQ

Dng nhit do bao b to ra. Dng nhit do bao b to ra tnh theo cng thc:

( ) ( )W360024

10002122

= ttCMQ bb

Trong :

bM : Khi lng bao b a vo kho cng sn phm

4,224%10%10 === MM b (t/ngy m)

bC : Nhit dung ring ca bao b. ( )kgKjCb /1460= (do y l bao b cacton) t1, t2: Nhit trc v sau khi lm lnh ca bao b

Ta chn t1 = 80C (do ta chn trong khong ( C085 )

t2 = -200C


Vy ta c

( ) ( ) ( )W56,1135360024

100020814608,1360024

10002122 =

+=

= ttCMQ bb

Vy dng nhit do sn phm v bao b to ra l:

[ ]W56,338556,1135225022212 =+=+= QQQ c. Dng nhit do vn hnh Q3:

c xc nh theo cng thc:

( )W35343332313 QQQQQQ ++++= Trong :

31Q : Dng nhit do n chiu sng (W)

32Q : Dng nhit do ngi lm vic to ra trong kho (W)

33Q : Dng nhit do ng c in to ra (W)

34Q : Dng nhit do m ca (W)

35Q : Dng nhit do x tuyt (W)

Dng nhit do n chiu sng to ra Q31 Dng nhit do n chiu sng to ra xc nh theo cng thc:

( )WF31 = AQ F: Din tch bung F = 468m2

A: Nhit lng to ra khi chiu sng trn 1m2 din tch bung W/m2

Chn A = 1,2 W/m2 ( do y l kho bo qun ng )

Vy

( )W6,5614682,131 === FAQ Dng nhit do ngi to ra Q32.

Dng nhit do ngi to ra xc nh theo cng thc:

( )W35032 nQ = Nhit lng do 1 ngi to ra khi lm vic nng nhc l 350W/ngi

n: s ngi lm vic trong bung. Ta chn 4 ngi lm vic trong bung

Vy ( )W1400435035032 === nQ .


Dng nhit do ng c in to ra. NQ = 100033 (W)

N Cng sut ng c in.

1000 H s chuyn i t KW ra W.

Tng cng sut ca ng c in qut dn lnh lp t trong kho lnh phi ly

theo thc t thit k. Tuy nhin n y ta cha chn c dn lnh nn cha bit c

th tng cng sut ng c in ca qut dn lnh, v vy c th ly theo nh hng

nh sau: i vi kho bo qun ng ly N = 6 KW.

Vy dng nhit tn tht do ng c qut dn lnh ta ra:

Q33 = 6KW = 6000 W.

Vy dng nhit do ng c in to ra l:

600061000100033 === NQ W

Dng nhit do m ca Q34. Dng nhit do m ca xc nh theo cng thc.

FBQ =34 (W)

Trong :

B: Dng nhit khi m ca, ta chn dng nhit khi m ca l )W/m(8 2=B

F: Din tch ca bung lnh. 2450mF =

Vy ( )W3600450834 === FBQ Dng nhit do x tuyt Q35.

Trong kho lnh khi x tuyt ta thc hin trn mi dn lnh nn ta ch vic tnh

ton cho 1 dn lnh .

Dng nhit do x tuyt c xc nh theo cng thc:

36002435

=

tCVQ kkkk

(W)

Trong : 3/2,1 mkgkk = : Khi lng ring ca khng kh.

V: Dung tch kho lnh. 3135031530 mV ==


kgKjCkk

/10091000009,1 == . Nhit dung ring ca khng kh.

Ct 09= . Nhit chnh lch trc v sau khi x tuyt.

Vy 27,170360024

9100913502,136002435

=

=

=

tCVQ kkkk

(W)

Vy dng nhit do vn hnh Q3 l:

87,1173127,1703600600014006,56135343332313 =++++=++++= QQQQQQ (W)

Bng 3-2: Bng tng kt nhit ti

Dng nhit

Kt cu bao che Q1 W

Sn phm to ra

Q2 W

My v

thit b

Q3 W

Q W

Tr s 11937,082 3385,56 11731,87 27054,512

3.1.3. Xc nh ti nhit v nng sut lnh cho my nn.

Ti nhit ca my nn cng c tnh ton t cc dng nhit thnh phn nhng

tu theo tng loi kho lnh c th ly mt phn tng ca ti nhit .

i vi kho lnh bo qun ta c.

++= 321 %75%100%85 QQQQMN 981,2233087,1173175,056,3385082,1193785,0 =++= MNQ W

Nng sut lnh cho my nn c tnh theo cng thc.

bQ

kQ MN=0 Trong :

:0Q Nng sut lnh ca my nn (W)

k: H s tnh n tn tht ng ng v thit b ca h thng lnh.

Chn k = 1,07

b: H s thi gian lm vic (chn b = 0,9)


Vy 054,265499,0

981,2233007,10 ===

bQ

kQ MN (W) 27KW

3.2. CHN CC CH LM VIC V CHN THIT B.

3.2.1. Chn cc ch lm vic.

1. Chn phng php lm lnh:

C hai phng php lm lnh nhng y ta chn phng php lm lnh trc

tip cho kho bo qun thu sn ng lnh v so vi phng php lm lnh gin tip th

phng php ny c nhng u nhc im tt hn hn.

Lm lnh bung trc tip l lm lnh bng dn bay hi t trong bung lnh.

Mi cht lnh lng si thu nhit ca mi trng bung lnh. Dn bay hi c th l dn

i lu khng kh t nhin hoc cng bc bng qut.

u im ca h thng lm lnh trc tip: Thit b n gin v khng cn thm mt vng tun hon ph.

Tui th rt cao, kinh t n gin hn v khng cn phi tip xc vi nc

mui l mt cht gy han g n mn rt nhanh.

Tn hao lnh khi khi ng nh.

t tn tht nng lng.

Nhit bung lnh c th gim st qua nhit si ca mi cht lnh.

Nhit si c th xc nh d dng qua p k u ht ca my nn.

D dng iu chnh nhit bng cch ng hoc ngt my nn.(My lnh nh

hoc trung bnh).

2. Chn mi cht lnh

Mi cht lnh l mi cht dng trong chu trnh nhit ng ngc chiu hp

th nhit ca mi trng cn lm lnh c nhit thp v thi nhit ra mi trng

c nhit cao hn.

Mi cht lnh c s dng ph bin trong cc h thng lnh ch yu l

Amoniac v Freon. Do vn la chn mt trong hai mi cht lnh cn tu


thuc vo nng sut h thng lnh, so snh tnh kinh t k thut cng vi ch

vn hnh m la chn hp l.

Chn mi cht lnh tun hon trong h thng l R22 - Cng thc ho hc

CHCLF2 l cht kh khng mu, c mi thm rt nh.

- Nhit si p sut kh quyn l - 40.80C.

- p sut ngng ph thuc nhit ngng.

R22 c s dng cho my lnh c nng sut trung bnh, ln v rt ln, R22

khng c i vi c th sng, khng lm bin cht thc phm bo qun, c ng

dng cho nhiu mc ch khc nhau c bit l trong k thut iu ho khng kh. N

c nhng u nhc im sau:

u im. - Nng sut lnh ring khi lng ln nn t khi lng mi cht tun hon trong

h thng.

- t c hi, khng c mi, khng gy n.

- Nng sut lnh ring th tch ln nn my nn my nn v cc thit b h thng

gn nh hn.

- Kh nng trao i nhit ln. Trong cc thit b trao i nhit vi nc b tr

cnh tn nhit v pha mi cht R22. Cc thit b trao i nhit gn hn.

- Kh nng lu ng ca mi cht ln hn trong cc ng ng nh hn.

- Khng dn in, d vn chuyn v bo qun.

Nhc im. - Gi c cao.

- Ho tan du hn ch, gy kh khn cho vic bi trn.

- Khng ho tan nc nn kh nng b tc m cao v lm cho nhit bay hi v

nhit ngng t gim, lm gim lng tc nhn lnh v t lm gim nng

sut lnh.

- n nhit ho hi ca R22 nh hn ca NH3 n 8 ln nn ch s dng cho h

thng va v nh.


Tuy c gi c cao nhng xt chung v c mt kinh t v k thut i vi h thng

cp ng v bo qun ng th s dng mi cht R22 vn p ng vn kinh t v k

thut. S dng R22 th my nn s c t s nn thp hn NH3, vn hnh thit b n

gin v an ton hn.

3. Chn cc thng s lm vic. Ch lm vic ca h thng lnh c c trng bi 4 yu t sau:

- Nhit si ca mi cht lnh t0.

- Nhit ngng t ca mi cht tk.

- Nhit qu lnh tql .

- Nhit hi ht v my nn hay nhit qu nhit tqn , th.

Chn nhit si ca mi cht lnh t0. Nhit si ca mi cht lnh ph thuc vo nhit bung lnh.

Nhit si ca mi cht lnh ly nh sau:

ttt b =0

Trong :

tb: Nhit ca bung lnh tb = -200C

t : Hiu nhit yu cu. Ct 0138 = . Chn Ct 08=

Ct 00 28820 ==

Chn nhit si ca mi cht l 280C

Nhit ngng t tk. Do y l dn ngng gii nhit bng khng kh nn hiu nhit trung bnh gia

mi cht lnh ngng t v khng kh l C0153 . Chn l 30C.

kkkk ttt +=

Trong Ctkk 03,37= y l nhit khng kh ly trung bnh trong nm Cn

Th (tra bng 1-1 SHDTKHTL)

Cttt kkkk03,4033,37 =+=+=

Nhit qu nhit tqn. L nhit ca mi cht trc khi vo my nn. Nhit hi ht bao gi cng

ln hn nhit si.


Cttqn0

0 155 += chn l chnh lch nhau 100C

Vy Cttqn 00 1810285 =+=+=

Ta chn nhit qu nhit nh vy do y khng c thit b qu nhit m ch

qu nhit do tn tht nhit trn ng ng ht t thit b bay hi v my nn .

Nhit qu lnh tql. y l nhit mi cht lng trc khi vo van tit lu . Do qu trnh qu lnh

v qu nhit xy ra rt t nhin nn ta c phng trnh sau:

1'1

'33 iiii ++=

Trong 1'1'33 ,,, iiii l entalpi ti cc im nt trn s sau

Do tqn =50C

V to = -200C

Nn tra trn th lgP-i ta c kgkji /6981 =

kgkji /700'1 =

T tk= 400C ta tra th lgP i ta c

kgkji /548'3 =

tql

tqn

i(kJ/kg)

Biu din cc thng s trn th lgPi

4 P0, T0

3' 3 Pk, Tk

1 1'

2


Thay vo phng trnh trn ta c

kgkjiiii /.5427006945481'1

'33 =+=++=

Tra th c tql = 350C

Vy nhit qu lnh l 350C

3.2.2. Tnh chu trnh my lnh.

1. Chu trnh my lnh.

Thuyt minh h thng

Hi mi cht sau khi sinh ra thit b bay hi, c nhit t0 v p sut P0, lng

hi ny s b tn tht nhit do ng ng dn gas nn nhit s tng ln nhit t1

v p sut P1. Sau n s c my nn ht v v nn nn n nhit v p sut t2

v P2. Sau n s qua dn ngng ti thit b ngng t ny mi cht s c gii

nhit bng h thng qut dn ngng y mi cht s thc hin nhim v chuyn pha

t pha hi sang pha lng v h nhit xung tk v gi nguyn p sut Pk. Sau n

s c qu lnh bng do tip xc vi ng ng ht ca my nn nn nhit ca

gas s gim xung cn t3.

Sau gas s qua thit b van tit lu v ti y van tit lu s lm nhim v h

nhit ng thi h p sut ca gas lng ny xung v tr 4 (t4, P4). Sau n qua

Dn ngng

Dn lnh

My nn

tql

tqn

Bieu dien tren o th P-i

4 Po,To

3'3Pk,Tk

11'

2

P(bar)

Van titlu


dn bay hi trao i nhit vi sn phm chuyn pha t pha lng sang pha hi. Sau

c my nn ht v v tip tc mt hnh trnh khp kn.

S thay i mi cht trong h thng.

1 1: Qu trnh qu nhit hi ht.

1-2: Qu trnh nn on nhit t p sut P0 n Pk

2-3: Qu trnh ngng t.

3 3: Qu trnh qu lnh mi cht trc khi vo van tit lu.

3 4: Qu trnh tit lu ng entalpi.

4 1: Qu trnh bay hi ng p.

Bng 3-3: Cc tng hp cc thng s trn cc im nt ca chu trnh.

Thng s

im nt

Nhit 0C

p sut

MPa

Entalpy

Kj/kg

Th tch ring

m3/kg

1

1

2

3

3

4

-28

18

80

40,3

35

-28

0,18

0,18

1,5

1,5

1,5

1,5

694

700

754

548

542

542

0,14

0,142

0,02 .

.........

-----------

2. Tnh chu trnh my lnh.

Qua vic tnh ton nhit kho lnh ta xc nh c nhit ti Q0MN. y cng l

nng sut lnh m my nn phi t c duy tr nhit lnh yu cu trong

bung lnh.

T nng sut lnh Q0MN = 27(KW) ta phi tnh nhit v chn my nn theo cc

bc sau.

Nng sut lnh ring q0 (kj/kg). 4

'10 iiq = (kj/kg).


Trong :

q0: Nng sut lnh ring (kj/kg)

4'1,ii : Entalpi ti im 1 v im 4 ca chu trnh.

1525426944'10 === iiq (kj/kg).

Lu lng mi cht mtt (kg/s).

178,010152

270003

0

0=

==

qQ

m MNtt (kg/s)

Th tch ht thc ca my nn Vtt (m3/s). 0253,0142,0178,01 === vmV tttt (m

3/s).

H s cp.

Ta c 33,818,05,1

0

===PPk

+

==

0

00

1

00

00

PPP

PPP

cP

PP mkkkltc

Trong :

: H s cp my nn. :,0 kPP p sut ht v ngng ca h thng MPa.

:01,0005,00 MPaPP k == Ta chn 005,00 == kPP MPa

m = 0,9 1,05 Ta chn m = 1

c: t l th tch cht c = 0,03 0,05 Ta chn c = 0,04.

+

==

0

00

1

00

00

PPP

PPP

cP

PP mkkkltc

68,018,0

005,018,018,0

005,05,104,018,0

005,018,0 11

=

+

=

Th tch ht l thuyt ltV .

0372,068,0

0253,0===

ttlt

VV (m3/s).


Cng nn on nhit sN . ( ) ( ) 612,9700754178,012 ==== iimlmN tttts KW.

Hiu sut ch th i .

( ) 75,028001,03,40273

282730

0=+

+

=+= btTT

ki

Trong

w L h s tn tht khng thy c w = kT

T0 .

b = 0,001.

Cng sut ch th iN .

816,1275,0

612,9===

i

si

NN

(KW).

Cng sut ma st. Cng sut ma st sinh ra do s ma st trong cc chi tit chuyn ng ca my

nn, cng sut ny ph thuc vo kch thc v ch hot ng ca my nn.

Ta c Nms = Vtt x Pms, KW

Pms: vi my nn freon ngc dng th.

Pms = (0,019 0,034)MPa.

Ta chn Pms =0,02 MPa.

Vy Nms= 0,0215 x 0,02 x 106 = 430 (W) = 0,43KW.

Cng sut hu ch. Ta c: Ne = Ni + Nms = 12,816 + 0,43 = 13,246 KW

Cng sut in. Cng sut in Nel l cng sut o c trn bng u in c k n tn tht

truyn ng, khp, ai v hiu sut chnh ca ng c.

Ta c. eltd

eel

NN

= , KW

Trong : td - l hiu sut truyn ng ai td = 0,95.

el - l hiu sut ng c. el =0,80,95


Vy: 49,159,095,0

246,13=

=elN KW

Cng sut chn ng c. Ta c: Ndc = (1,1 2,1 ) x Nel KW;

Chn h s an ton l 1,2.

Nn ta c Ndc = 1,2 x 15,49 = 18,59 KW.

Nhit thi ra thit b ngng t. 816,39816,12270 =+=+= ik NQQ (W).

3.2.3. Tnh chn thit b.

1. Chn cm my nn dn ngng. Do qu trnh tnh ton tnh Qo = 27KW v cng sut ng c Ndc = 18,59 KW

nn ta chn h thng my nn v dn ngng nguyn cm do hng Bitzer ca c sn

xut vi cc thng s sau:

Model: LH135/4N.2-S

Th tch qut: 56,1 m3/h

Cng sut ng c: 11 KW

Nng sut lnh: 11,2 KW

Ghi ch: LH135 - Kiu dn ngng.

4N.2 - Kiu dn lnh.

y l my nn mt cp. Vi cc thng s trn phc v cho kho lnh 400 tn

ta phi cn 3 h thng cm my nn v dn ngng mi m bo bo nng sut lnh.

Hnh 3-1: Cm my nn dn ngng


2. Chn dn lnh.

Dn lnh l mt thit b trao i nhit trong gas lng thu hi nhit bc hi.

Dn lnh ti chn l dn lnh khng khi i lu cng bc, t tn din tch trong

kho, nhit trong bung u, h s trao i nhit ln, nhng nhc im l n v tn

nng lng cho qut ca dn lnh.

Do Qo = 27KW m kho lnh c 3 dn lnh nn mi dn phi t nng sut l t

nht 9KW. Nn ta chn dn lnh do hng Gao Xiang Trung quc sn xut.

Dn lnh c chn vi cc thng s sau:

Thng s ca qut in tr si

Cng sut, dng in, ngun in K hiu

Nng sut

lnh

KW

Din tch

trao i

nhit m2

Lu

lng

m3/h

Khong

thi

m V/Hz W A V/Hz KW

GX-LE403-

1500

9,2 57,3 12705 15 230-400/50 450 1,65 200/50 9,96

Ghi ch: GX-LE 40 3-1500

3. Tnh chn cc thit b ph.

a. Tnh chn van tit lu.

Dn bay hi c nhiu ng nhnh phn phi mi cht v mc tn tht p sut

trong dn bay hi ln nn m bo cung cp mi cht cho dn lnh nn y ti

chn v vic chn van tit lu t ng cn bng ngoi cho kho bo qun ng cn c

vo cc thng s sau:

Nhit ngng t: tk = 40,30C.

Hnh32: Dn bay hi

Cng sut ng c my nn i km 15HP S qut gi

ng knh qut 400


Nhit qu lnh: tql = 35 0C.

Nhit bay hi: ts = -28 0C.

Nng sut lnh: Qo = 27 KW .

- Xc nh p sut u vo van tit lu:

p sut ngng t 40,3 0C l: 1,5 MPa = 217,5 PSI.

Tr tn tht p sut trn ng cp lng: 2 PSI.

Tr tn tht do ct p thy tnh 10 feet: 5 PSI.

p sut u vo van tit lu: 224,5 PSI. - Xc nh p sut u ra van tit lu:

p sut ca R22 28 0C l 0,18 MPa = 26,1 PSI.

Cng tn tht p sut trn ng ht: 2 PSI.

Cng tn tht p sut trn ng ht: 20 PSI.

p sut u ra van tit lu: 48,1 PSI. -Xc nh hiu p sut: P = 224,5 48,1 = 176,4 PSI.

Theo bng 8.2 [1 ] ta chn van TCL 700H tit lu l van tit lu cn bng ngoi. Cu to ca van tit lu nh sau:

Van tit lu mng ch m khi trng thi mi cht

lnh ra khi thit b bay hi trng thi hi qu nhit. Gi f l din tch b mt mng xp. Nu nhit ra khi mi cht l hi qu nhit th tqn > t0 do nhit mi cht trong bu cm bin cng c coi l nhit qu nhit, khi

1: Np chp 2: Vt iu chnh. 3: Mi cht lnh vo thit b bay hi. 4: L xo. 5: Ty van. 6: Ni vi ng cn bng

p sut ngoi. 7: Mng xp. 8: Bu cm bin. 9: ng mao. 10: Ty van. 11: Dch vo.

12 11

10

98

7

6

3

45

21

P 1 = f(t qn )

P h

R

Hnh 33: Cu to van tit lu


trng thi mi cht trong bu cm bin l hi bo ho tqn c p sut bo ho Pt. + Phng trnh cn bng lc: Pt. f = P0+R; (Pt P0). f = R khi trng thi

mi cht sau khi ra khi thit b bay hi ti bu cm bin l hi bo ho kh th van tit lu ng.

+ Khi my mi chy th nhit qu nhit tqn tng i ln hn nhit t0 nn van tit lu m ln.

+ Khi my dng th van tit lu ng li. Trong thc t cho my nn vn hnh c an ton th trc van tit lu phi lp thm mt van in t lc my nn chy van in t c in m ra cp dch cho dn bay hi, v my dng van in t ng li.

V tr lp t.

Van tit lu mng cn bng ngoi bao gi cng c lp t sau van in t v trc dn lnh. N ch m khi trng thi mi cht sau khi ra khi thit b bay hi ti bu cm bin phi l hi qu nhit.

b. Tnh chn bnh cha cao p.

Nhim v ca bnh cha cao p l cha gas lng sau khi ngng t phn phi

n cc dn lnh.

Bnh cha cao p c b tr v pha cao p v nm sau dn ngng. N gii

phng b mt truyn nhit ca dn ngng bi lp cht lng ng thi cung cp ng

u lng cht lng cho van tit lu.

Th tch bnh cha cao p chn nh sau:

( ) '3'3 200022501500 vGvGV ==

Hnh 34: S lp t van tit lu


Trong :

V: th tch bnh cha cao p m3

G: Lng tc nhn lnh i qua bnh cha cao p.

G = mtt = 0,178 Kg/s

v3: Th tch ring cht lng nhit tk (m3/kg). 3

'3 1088,0=v m3/kg

Vy 313,01088,0178,020002000 3'3 === vGV m3

T th tch ca bnh cha ta tnh ton th ta chn bnh cha vi cc thng s sau:

Th tch bnh: 0,329 m3

Chiu di bnh: 865 mm

ng knh trong: 220mm

ng knh ngoi: 290mm

c. Tnh chn bnh tch lng.

ng knh bnh tch lng c tnh nh sau:

Phng trnh cn bng lu lng.

btth mm =

skgmvV

m tth

bt /178,01

===

=4

2DVh

sm /5,0=

mmmvm

D tt 254254,05,014,3142,0178,044 1

==

=

=

Chn bnh tch lng c ng knh trong 254mm

d. Phin lc.

Phin lc c nhim v loi tr cn bn trnh hin tng tc van tit lu. Ngoi

ra cn c nhim v loi b cc Axid v cc cht khc ra khi vng tun hon mi cht

lnh. Phin lc c lp trn ng cp lng cho dn bay hi v c lp t trc van

in t.


f. Van in t.

Van in t l van chn c iu khin bng lc in t. Khi c in cun dy s sinh ra lc in t ht li thp v y van ln, van in t m ra cho dng mi cht i qua, khi khng c in van in t ng li ngng cp dch. Van ch c hai ch l ng hoc m.

Hnh 34: phin lc cho thit b my lnh freon.

Hnh 36: Cu to van in t.

1: Thn van. 7: V.

2: van. 8: Cun dy din t

3: Clppe. 9: Vt c nh

4: ng dn hng ng thi l ng ngn cch 10: Vng on mch chng n.

khoang mi cht vi bn ngoi. 11: Dy tip in.

5: Li st. 12: M c ni vt.

6: Li c nh. 13: L xo.


g. Van chn v van tp v. + Nhim v ca van chn l khi vn

hnh, bo dng, sa cha h thng lnh cn thit phi kho hoc m dng chy ca

mi cht lnh trn vng tun hon. +Van tp v c lp t trn u

ca my nn ng ht v ng y

ca my nn. Van tp v c nhim v l

bo dng, sa cha, np du, np gas, ht

chn khng cng nh phc v cho vic o c

v kim tra my nn.

a. Bu lng bt ln my nn

b. Loi hai bu lng bt ln my nn.

c. Mt ct qua van tp v.

d. Hnh ct phi cnh.

h. Cc r le bo v.

R le p sut kp.

1. Thn. 8. u ni ht chn khng, np gas h thng.

2. van 9. u ni dn ngng hoc dn bay hi.

3. Tm chn di. 10. Tai c nh vo u my nn.

4. m kn trc. 11. Vng sit.

5. m np. 12. u bulong.

6. Np. 13. Tm chn trn.

7. Trc van. 14. u ni vo my nn.

Hnh 39: R le bo v p sut kp.

Hnh 38: Cu to van tp v.

Hnh 37: van chn ca h thng.


Hnh 311: Cu to v v tr lp t ca mt ga

Bo v thit b khi c s c v p sut nh tng hoc gim t ngt. Lc Rle

s nhn tn hiu v tc ng n h thng iu khin v lm ngng hot ng cu my

nn, ng th n s c v mch bo ng s c lm vic.

R le hiu p sut du.

My nn c bi trn bng du, du c bm du ht t cacte a qua cc

rnh du b tr trn trc khuu v cc chi tit n cc b mt ma st do hiu p sut

du v p sut ht c ngha quan trng i vi qu trnh bi trn my nn khi p sut

du khng th trong khong 60 - 90 giy in tr s t nng lm cho thanh lng

kim bin dng dn ti m tip im, my nn dng, nu p sut du th tip im

OPS m ra my nn hot ng bnh thng.

i. Mt gas.

Mt gas l knh quan st lp t trn ng lng

(sau phin lc sy) quan st dng chy ca mi

cht lnh. Ngoi vic ch th dng chy n cn

c nhim v:

Hnh 310: R le bo v p sut du.


+Bo hiu gas khi dng gas khng b si bt.

+Bo hiu thiu gas khi dng gas b si bt mnh.

+Bo hiu ht gas khi thy sut hin cc vt du trn knh.

+Bo mi cht qua s bin i mu ca chm mu trn tm mt.

4. Tnh chn ng ng dn mi cht trong h thng.

Trong h thng lnh gm nhiu thit b ring bit, chng lin kt vi nhau nh

cc ng dn, v vy phi tnh ton la chn ng ng dn sao cho va bn v va

tit kim ng ng m bo yu cu k thut v kinh t.

Cng t cc yu t nh: tc lu ng cho php ca mi cht, lu lng ca

dng mi cht, khi lng ring ca mi cht T ta tnh ng knh ng dn.

ng knh trong ng c xc nh theo biu thc:

=

md 4 (m)

Trong :

m: Lu lng (kg/s).

: Khi lng ring ca mi cht (kg/m3).

: Tc dng chy trong mi cht (m/s).

Trong h thng lnh ta cn xc nh 3 ng ng l ng ng ht t thit b

bay hi v my nn, ng ng y, v ng ng dn lng.

a. ng ng ht t dn bay hi v my nn.

Ta c:

=

1

4 mdh

m = 0,178kg/s

Theo bng 10 1 (TL1) ta c: 127 = m/s nn chn 10= m/s

v1 = 0,135 m3/kg nn 135,011

11 == v

Vy mmmd h 55055,01014,3135,0178,044

1

==

=

=


Vy chn loi ng st c ng knh mm55 lm ng ng ht my nn. Chn

dh = 60mm.

b. ng ng y ca my nn t my nn n thit b ngng t.

Ta c:

=

2

4 mdn m

m = 0,178kg/s

Theo bng 10 1 (TL1) ta c: 158 = m/s nn chn 10= m/s

v2 = 0,02 m3/kg nn 02,011

22 == v

Vy mmmd n 21021,01014,302,0178,044

1

==

=

=


dn = 25mm.

c. Tnh chn ng ng dn lng.

Ta c:

=

3

4 mdl m

m = 0,178 kg/s

Theo bng 10 1 (TL1) ta c: 14,0 = m/s nn chn 7,0= m/s

v2 = 0,88*103 m3/kg nn 32

2 1088,011

==

v

Vy mmmd n 17017,07,014,31088,0178,044 3

1

==

=

=


dl = 19mm.


Bng kt qu tnh ton ng ng chn.

Kch thc chn ng ng

ng knh tnh c

mm ng knh trong

mm

ng knh ngoi

mm

ng y

ng ht

ng dn lng

21,2

55

16

25

60

19

28

67

22

3.3. B TR MY V THIT B. Sau khi hon thnh xong cng tc thit k th phi b tr my v thit b cho ph

hp. Di y l s mt bng ca kho lnh d kin s thit k vi cc thit b c

lp t vo cc v tr sau:

Hnh lang lnh

1. Ca ln ca kho lnh.

2. Ca nh ca kho.

3. Tm panel cch nhit.

4. Dn lnh.

5. Cm my nn dn ngng ca hng Bitzer

Hnh 3.12: S mt bng kho lnh


1. panel cch nhit.

2. Con lun thng gi.

3. Lp b tng chu lc.

4. Nn t .

5. Ca nh.

6. Ca ln.

7. Khung mi che.

8. Dn lnh.

Hnh 3-13: Mt ct kho


CHNG 4: THI CNG LP T

4.1. GIA C V XY DNG NN MNG.

y l mt cng on quan trng trong qu trnh xy dng kho, n quyt nh

tnh vng chc v an ton ca kho. Mng c o su 70cm. c ca cc ct b

tng ct thp. Sau ta c cc ct b tng n chiu cao bng mt nn kho thit k,

tin hnh xy mng t vo nn to vng chc ca nn. Sau c lp b

tng chu lc v xy cc con ln bng gch.

4.1.1. c khung kho bng b tng ct thp.

Sau khi xy dng xong mng kho, nn kho tin hnh c cc ct b tng theo

chiu cao v kch thc thit k. Trn cng ca cc ct c lin kt vi nhau bng

cc dm b tng ct thp.

Cng vi vic xy dng khung ta tin hnh xy tng bao cho nhng tng cn thit.

4.1.2. Dng khung mi v lp mi.

Sau khi c c khung b tng ca kho ta tin hnh dng khung st mi, lp cc

x dc theo chiu di ca kho v tin hnh lp tn. Sau khi c c b khung vng chc

cho vic lp ghp cc cu trc cch nhit.

4.2. LP T KHO LNH.

4.2.1. Cng tc chun b.

+ Trc khi lp t kho lnh th phi chun b dng c lp t cho y nh

l: panel, thanh nhm V v thanh thp ch U, tn rive, khoan, my ct

+ Chun b bo h lao ng cho ngi thi cng.

+ o c k trc khi lp t.

4.2.2. Thi cng lp t.

+ u tin ta lp phn panel vch trc nhng cha mt vch pha Ty Bc

ra v vch ny khi lp xong panel nn ta mi lp.

+ Lp lun ca ra vo kho lnh v ca s.

+ Lp n panel nn.

+ Lp panel vch cn li.


+ Lp cc x gi panel trn.

+ Lp panel trn.

1. Lp panel vch. a. lp vch kho lnh.

t hai tm panel li gn nhau v dng c cu kho cam lp ghp n li.

Cch lp bng kho cam ta trnh by nh hnh v 4-1.

Sau khi lp xong phi bn keo silicon vo cc khe h gia hai tm panel

trnh m lt vo cc tm panel.

Sau cng phi cho nt che l a lc gic vo bng nt nha trnh m vo

tm panel.

Ch : khi cho nt vo ta phi bn keo vo nt cch li tm panel vi m bn

ngoi, v gi nt cho chc chn.

1: Kho cam

2: L dng lc gic iu khin khoa cam.

3: Cht panel th hai gi kho cam

4: Cht panel th nht gi khoa cam khng b bt ngc lai sau.

4

3

2

1

Hnh 4-1: Cch kho tm panel

1: Panel tng th nht.

2: Panel tng th hai.

3: C cu kho cam.

4: Nt che l kho cam.

4

23

1

Hnh 4-2: Cch lp panel vch.


b. Lp panel vch gc kho lnh (hai vch vung gc vi nhau).

t hai tm panel nh hnh v 4-3.

Sau dng cc thanh thp ch V c nh hai tm li vi nhau. Cc thanh

nhm ny va c nh va chng m cho tm panel.

Dng cc con tn rive c nh thanh nhm ch V vi panel.

Cn mt vch ta lp panel nn trc ri mi lp vch c ( l vch pha

Ty Bc).

2. Lp ca ra vo v ca s. y k c ca ra vo v ca s u dng loi ca kiu bn l.

o c xem v tr t ca nm u .

Dng my ct ct mt l ng bng kch thc ca .

1: Tm panel vch 1.

2: Tm panel vch 2.

3: Thanh nhm hnh ch V.

4: Tn rive.

1 4 3

2

Hnh 4-3: Lp panel vch gc kho lnh.

54 3

2 1

Hnh 4-4: Ca kho lnh

1: Ca kho lnh.

2: Tm inox gi

ca vi panel

3: Kho ca.

4: Cht kho.

5: Bn l.


t ca vo v tr .

Dng khoan khoan l v bn rive vo tm s 2 c nh ca vi panel.

3. Lp panel nn. Lp panel nn nh hnh v.

Trc tin lp tm panel nn v vch trc. t hai tm panel vung gc vi

nhau sau dng thanh nhm mng ch V t gc v bn tn rive vo gi thanh

thp c nh hai tm panel li vi nhau. y thanh nhm ch V ny ch co tc dng

chng m cho tm panel thi.

Sau lp cc tm panel nn vi nhau. Cc tm panel nn c lp vi nhau

bng c cu kho cam nu mc trc.

4. Lp panel vch cn li. Cch lp panel vch cn li ta lp nh hnh v 4-6.

1: Panel nn.

2: Panel vch.

3: Tn rive.

4: Thanh nhm ch V. 43

2

1

Hnh 4-5: Lp panel nn v vch

1: Panel vch .

2: Panel nn.

3: Tn rive.

4: Thanh nhm ch V. 432

1

Hnh 4-6: Lp panel vch v nn


t hai tm nh hnh v. V dng cc thanh nhm mng ch V v tn rive c

nh n li nh trnh by mc trc.

5. Lp x gi panel trn. Do panel trn khng c ct nn dng cc x gi cho trn kho khng b

ri xung di.

X treo ny thng dng thanh thp hnh ch U.

6. Lp cc panel trn. Sau khi lp xong cc x ta tin hnh lp cc panel trn.

u tin lp cc trn pha Ty Bc trc cch lp trn ny nh hnh v 4-8.

1: Panel vch pha Ty Bc.

2: Panel trn kho lnh.

3: Bulong d.

4: ai c gi bulong d.

5: Dy cp theo panel trn.

6: C cu tng.

7: Thanh thp ch U.

8: Tn rive.

9: Thanh nhm ch V.

10: X g.

10 9 8 7 6

5

4

3 2

1

Hnh 4-8: Lp panel trn pha Ty Bc

Hnh 4-7: Cch `lp x treo

1: X treo.

2: Tng .

3: Dy cp.

4: X g trn mi kho. 1

2

34


Lp panel trn sau ta dng cc bu long d bt xuyn qua panel trn c nh

panel trn vi x treo hnh ch U, x treo gi panel trn khi b ri xung di

(Lp bulong d phi cho mt t keo silicon vo phn d p vo panel trn n gi

cho bulong d khng b xoay chuyn khi ta sit ai c pha trn).

Sau tin hnh bt thanh nhm s 9 v tn s 8 nh hnh v 4-8. Khi lp xong

panel trn u tin th lp panel tip theo cng hng tng t nh vy, nhng trc

khi bt bulong d phi hai tm panel gn nhau v khoa chng bng c cu cam

trc sau mi tin hnh lp bulong d vo v tng t nh trn.

Sau khi xong hng th nht phi cng dy cp bng c cu tng cho dy cp

cng ra gi panel tt hn.

Sau khi lp xong hng th nht tin hnh lp hng th hai. Lp hng th hai thc hin theo hnh v 4-9.

`

1: Panel trn hng th nht.

2: Panel trn hng th hai.

3: Thanh nhm lp khe h gia hai

panel.

4: Bulong d.

5: Thanh thp ch U.

6: C cu tng.

7: Dy cp.

8: X g.

8 7 6 5

3 4

2 1

Hnh 4-9: Lp panel trn hng th hai


t hai tm panel gn nhau v cng thc hin nh hnh v. Nhng do hai tm

panel ny khng c c cu no n khp vi nhau nn ch t chng gn nhau v

dng thanh nhm s 3 lp khe h ca hai lp panel .

Sau khi lp xong hng th hai ta tin hnh lp hng th ba. Lp hng th ba tin hnh nh hnh v 4-10.

1: Tm panel hng th hai.

2: Tm panel hng th ba.

3: Tm panel kho lnh th hai.

4: Panel vch .

5: Bulong d.

6: Thanh nhm ch V.

7: Tn rive.

8: Thanh thp ch U.

9: C cu tng.

10: Dy cp treo.

11: X g.

4

3

7 6 5

89

1011

21

Hnh 4-10: Lp panel trn hng th ba.


Do y l tng pha ng Nam nn n gip vi kho lnh th hai nn tin hnh

lp nh hnh v 4-10.

Sau khi lp xong panel trn hng th ba ny xong l hon thnh lp xong kho

lnh. V gi tin hnh lp t h thng lnh.

4.3. LP T H THNG LNH.

Do y l h thng lnh c trung bnh nn theo xu hng hin nay lp t chng

theo hai cm. Mt cm gm h thng my nn, dn ngng v cc thit b ph khc.

Cn cm my cn li l cm dn lnh v van tit lu.

4.3.1. Lp t cm dn ngng, my nn.

Lp t cm ny nh hnh v 4-11. `

`

1: Qut dn ngng.

2: Dn ngng.

3: My nn.

4: Bnh cha cao p.

5: ng gas v dn lnh.

6: Khung .

7: ng gas t dn lnh v.

Hnh chiu cnh Hnh chiu ng

Hnh 4- 11: Cch lp cm dn ngng, my nn

4

21

sn b tng

7

5

36


Trong lp t h thng th lp t cm ny l kh nht do n gm nhiu b phn

quan trng ca h thng nh my, nn, dn ngng, mch in, cc thit b bo v h

thng Nn phn ny thng lp trc xng xong xui, chy th xong xui th

mi em n cng trnh ch vic t n ln vi tr lp t l xong.

Do yu cu v nng v cng knh nn khi lp cm ny ta phi tch ri dn

ngng v cm my nn thnh hai. Khi a cm my nn vo v tr lp t ri mi a

dn ngng ln. Khi da dn ngng ln xong phi dng bulong-ai c sit cht chn

dn ngng vo khung ca cm my nn v cm my nn phi c c nh tht

chc vo sn b tng. V khi my hot ng n s to ra rung ng mnh nu khng

c nh chc chn n s b dch chuyn v gy nh hng n h thng.

Sau khi c nh xong cm my ny tin hnh lp ng ng ni t bnh tch

du n dn ngng v t dn ngng n bnh cha cao p.

Ch : Khi lp cm my ny vo sn b tng th phi o c sao cho cm my

ny phi cch tng khong 1m khi lp t ng ng ht khng b vng lm cho

gi tr thm m khng cao.

4.3.2. Lp t cm dn lnh.

Lp cm dn lnh ta thc hin theo hnh v 4-12.

Hnh 4- 12: Cch treo dn lnh.

1110

87 6

5 4 32

1


Trc khi a dn lnh ln ta phi o c v tr lp t dn lnh cho ph hp.

Sau ta khoan l cho thanh thp ch U s 7 sao cho khong cch cc l ca n phi

bng khong cch cc l trn thanh thp ch U trn dn lnh.

Sau khi khoan l xong xui tin hnh treo thanh thp s 7 ln trn x g s 11

v a thanh ty 4 vo ng v tr nh hnh v, khi cho dn lnh ln ta ch vic x

thanh ty vo cc l trn thanh thp ch U s 3 v sit ai c vo l xong phn lp t

dn lnh.

Ch : Khi lp dn lnh ta phi ch y khong cch cha dn lnh v vch kho

lnh n phi cch vch khong 0,5m khng kh i lu c d dng m khng b

vch cn s i lu .

Sau khi lp xong dn lnh ln th ln nc kho lnh tng dy cp bng c cu

tng ln cho hp l.

4.3.3. Lp t ng ng ht ca my nn, v ng ng t nh cha cao p

n dn lnh, bnh tch lng v van tit lu.

1. Lp t ng ng ht ca my nn v bnh tch lng. ng ht ny dng bng ng thp nn ta lp t theo cc bc sau:

Trc khi lp t ng ng phi lm v sinh bn trong ng cho sch s

(thng dng gi lau v dng cy gy di lau).

o c v ct ng theo ng kch thc m o trc. Sau khi ct ng xong

phi lau li ng mt ln na mt st trong ng ra ngoi.

1: Dn lnh. 8: Dy cp mc tng.

2: Qut dn lnh. 9: Tng.

3: Thanh thp ch U trn dn lnh. 10: X g trn mi.

4: Thanh ty. 11: Dy cp.

5: ai c.

6: Panel trn.

7: Thanh thp ch U phn b lc u trn panel.


Lm cc gi treo ng (do y l ng st nn rt nng, phi lm gi treo ng phi

chu c trng lng ca ng ng).

a cc ng ln gi treo sao cho hp l.

Dng my hn in hn cc ch mi ni, cc co (ch : ch nhng th hn

p lc c tay ngh cao mi c hn).

Do bnh tch lng nm trn ng ht t dn lnh v mt nn nn trng qu

trnh lp ng ht my nn tin hnh lp lun bnh tch lng. Bnh tch lng ny l

dng bnh treo nn ta khng cn lm gi cho n m ch vic hn hai mi hn l

ng ng t dn lnh v bnh tch lng v t bnh tch lng v my nn nh

hnh 4-13.

2. Lp ng ng t bnh cha cao p n dn lnh, v van tit lu. ng ng ny nh nn dng loi ng ng. Lp t ng ng ng cng

tng t nh lp t ng ng st nhng n d dng hn. V khng phi lm gi

treo ng.

Trc khi lp van tit lu phi tin hnh ui bi ng ng va lp. ui bi

bng cch dng kh N2 ui nh hnh v.

Sau khi ui bui xong th tin hnh lp van tit lu v van tit lu nm trn ng

dn t bnh cha cao p n dn lnh.

Cch lp van tit lu nh hnh v 4-14:

5 43

2

1

Hnh 4-13: Lp t bnh tch lng

1: Bnh tch lng

2: B gim ng.

3: Mi hn in.

4: ng st.

5: Co ng st.


Trc ht lp c van tit lu ta phi bit c v tr lp t van tit lu l

ngay st thit b bay hi trn ng dn lng vo.

Lp t van theo ch dn ca mi tn trn thn van (ch : khng ng mao

tip xc vi cc ng khc).

Lp ng cn bng ngoi: Ta dng ng cn bng ngoi l ng ng 6. Lp ng 6 vo van bng cch loe ng v dng c u cn sit cht n li. Cn lp u kia vo ng st th phi ly b hn gi h nng mt phn ng st cho n nng n

khi gn chy th cho ng ng vo n khoan thng mt l va bng ng ng. Sau

ta dng que hn ng thau hn ng ng vo ng st.

Lp bu cm bin: V tr lp bu cm bin l t li hi ra khi dn bay hi

(ng st) v m bo tip xc tt vi ng ny dng bn kp bng nhm gi n c

nh vo ng st.

3. Lp t ng ng nc ngng. ng nc ngng thng lp t bng ng nha PVC. Sau khi lp t ng

nc ngng xong ta phi bc cch nhit cho ng nc ngng ny. L do bc cch

nhit l cho khng xy ra ng bng trn ng ng nc lm h hi n ng

nc, v khng cho nhit t nc x ny nh hng ti dn lnh.

4. Qu trnh bc cch nhit ng ng.

Sau khi th x h thng xong nu khng b x ch no ta tin hnh bc cch nhit

ng ng.

Hnh 4-14: V tr lp t van tit lu

1: Dn lnh.

2: ng cn bng ngoi.

3: ng t bnh cha cao p n.

4: ung v my nn.

5: Bu cm bin.

6: Van tit lu

6

54

3

21


Bc ht phn ng t dn lnh v my nn. Trong qu trnh bc ng ng ta tin

hnh bc lun c bnh tch lng trnh tht thot nhit.

4.4. UI BI V TH X, HT CHN KHNG V NP GAS H THNG.

4.4.1. Quy trnh ui bi h thng.

Do qu trnh ui bi ta thc hin i vi ng ng ri v cc thit b cm

my nn, v dn ngng nn by gi ta ch vic ui bi cc ng st na thi.

Qu trnh ui bi tin hnh nh sau:

M phn van ni vi van tit lu ra sau tin hnh t chai Nit v cho

kh Nit vo hng (hnh v 4-15).

M mt bch ca van ht my nn ra.

76

5

4

3

2 1

Hnh 4-15: Cng tc ui bi ng ng st

1: Dn lnh.

2: ng ng sau van tit lu.

3: ng st.

4: Dy np gas.

5: Chai Nit.

6: Bnh tch lng.

7: Mt bch ca van ht.

Hnh 4-17: Cu to ng ng sau khi bc cch nhit

1: Vt liu cch nhit PU. 2: V tn bc bn ngoi. 3: ng ng. 4: ng st.

4 3

1

2


Ta tin hnh kt ni nh hnh v. Sau khi kt ni xong th mt ngi ng

ch mt bch v dng tay bt cht mt bch li, cn ngi th hai m van chai Nit ra.

Ngi m c khong 15 giy th ng van Nit li sau li m li khong 3 n 4

ln. Cn ngi my nn th bt cht tay vo mt bch khi no thy kh Nit ra vi p

lc cao m tay khng gi c na th bung tay ra cho bi bay qua li , v tip tc

lm nh vy khong 3 n 4 ln na l xong.

4.4.2. Th x h thng.

Sau khi ui bi h thng xong tin hnh th x h thng.

Th x h thng ta cho kh Nit vo th. Cho kh Nit vo h thng pha cao

p l 16bar cn pha h p l 10bar.

Thi gian gi p sut l 12 gi. Trong 6 gi u p sut cho php h khng qu

10%, sau phi gi khng i.

Sau khi bm p sut bn pha cao p v h p th ta ng chai Nit li v

dng bt x phng th cc ch hn v cc mt bch ca my nn xem c b x ch no

khng. Nu m b x th phi x ht Nit ra ngoi v khc phc, hoc hn li, khi gii

quyt xong s c li bm Nit vo v lm li t u.

Cn nu qua thi gian th x m khng thy x ch no v p sut lun m bo

th phi x ht Nit ra v tin hnh ht chn khng h thng.

4.4.3. Ht chn khng h thng.

Qu trnh ht chn khng c trnh by hnh v 4-16.

87

5 6

E

D C B

HP LP

4

3

A

1 2

Hnh 4-16: S qu trnh ht chn khng


`

Qu trnh ht chn khng kt ni nh hnh v 4-16. Sau khi dy gas kt ni vi

cc gic co A, B, D, E th tin hnh bt my ht chn khng cho n chy. Ht n khi p

sut ng h LP chi v vch 30mmHg th cho my chy thm 1 gi na, sau cho

my nghi mt lc sau ht li ln na. C lm nh vy khong 3 n 4 ln l . Trong

qu trnh ht chn khng ta kt hp sn dng ng st (sn ng ng bng sn mu ).

4.4.4. Np gas cho h thng.

Np gas vo h thng ta thc hin theo s :

1: ng nn ca my nn.

2: ng ht v ca my nn.

3: Van ht.

4: My nn.

5: My ht chn khng.

6: ng khng kh c ht ra.

7: Van cao p ca ng h np gas.

8: Van thp p ca ng h np gas.

Cc thit b trong qu trnh ht chn

khng: Dy gas, ng h np gas, my

ht chn khng.

1:ng nn ca my nn.

2: ng ht v ca my nn.

3: Van ht.

4: My nn.

5: chai gas.

7: Van cao p ca ng h np gas.

8: Van thp p ca ng h np gas.

A,B,C,D,E: Cc gicco kt ni.

E

8 7

4

3

D C B

A

12

HP LP

5

Hnh 4-17: Cch np gas h thng.


Sau khi chn khng h thng, ni bnh vi nhnh van ht ng van s 7

v m van s 8 ra sau ta m van chai gas ra gas vo h thng thng qua chnh

lch p sut. Sau cho my chy v iu chnh p sut ht khng vt qu 1.5 n 2

bar. Cho my chy my nn ht ht phn gas trong chai gas. Np gas cho n khi

p sut ht khong 1 bar l . Khi xong ng van s 8 ri ng van chai gas. Sau

tho b np gas ra v cho my tip tc chy kim tra xem co cn s c no na

khng. Nu khng c s c no th ta kt thc qu trnh lp t h thng ti y.

4.5. MCH IN NG LC V IU KHIN CA H THNG.


Thuyt minh mch in

Khi cp dch cho h thng. ng cng tc ON th SW1 v v tr cun dy AX3 m

ra, khi dy in tr a-b khng c t nng v tip im 1-2 ng, tip im 1-3

m ra. Lc ny c in vo cun dy AX1.

Khi cun dy AX1 c in lm cho tip im thng ng AX1 m ra lm cho

khng c in vo n R v n R khng sng. Cn tip im thng m AX1 s

ng li v c in vo cun dy r le thi gian x tuyt T1. Thi gian x tuyt c

ci t sn (khong 4 ln trong mt ngy, mi ln x l 20 pht). Khi cun dy T1 c

in th tip im thng m ng chm T1 vn m lm cho cun dy MH (cun

dy r le x tuyt) khng c in, v tip im thng ng MH ng li v c in

vo cun dy ca qut dn ngng v qut dn lnh MF1 v MF2, khi dn ngng v

dn lnh hot ng.

ng thi vi qut dn ngng v dn lnh hot ng th cun dy AX2 c in

do tip im thng ng m chm T1 vn ng, Khi cun dy AX2 c in ng

thi tip im thng m AX2 ng li v c in vo cun dy AX3, lm cho tip

im thng m AX3 ng li v my nn hot ng. My nn khi ng theo kiu

/ . Khi tip im AX3 ng li c in vo cun dy r le thi gian T2, v vo

cun dy MC lm cho tip im thng m MC ng li v c in vo cun dy

MS khi nay my nn chy ch sao (Y ), sau thi gian ci t trn r le T2 th tip

im thng m ng chm T2 ng li, v tip im thng ng m chm T2 m

ra v c in vo cun dy MD, ng thi tip im thng ng MD m ra lm mt

in vo cun dy MS, v tip im thng m MD ng lai duy tr in vo

cun dy MC khi ny 2 cun dy MC v MD c in lm cho my nn chuyn t ch

sao sang ch tam gic .

Trong qu trnh hot ng nu m p sut du khng t th tip im thng m

OPS s ng li lm cho dy in tr c in v n s nng ln v tc ng lm tip

im 1-2 m ra, tip im 1-3 ng li lm mt in vo cun dy AX1 v my nn,

dn ngng, dn lnh mt in. Tip im thng m OPS c tc dng cm nhn p

sut du kp thi ng ngt nu p sut du gp s c.


Trong h thng cn lp t thm r le p sut kp trnh p sut ht hoc p

sut nn cao bt thng hoc thp bt thng. Nu gp s c th tip in thng ng

LP hoc HP s m ra lm mt in vo cun dy AX3 khi my nn s mt in.

Khi n thi gian x tuyt th tip im thng m ng chm T1 ng li cn

tip im thng ng m chm T1 m ra lm cho cun dy MH c in ng thi

mt in cun dy MF1 v MF2. khi bt u v thi gian x tuyt, thi gian x

tuyt th n G s sng. Khi ht thi gian x tuyt th tip im thng m ng chm

T1 s ng li cn tip im thng ng m chm s m ra v qut dn ngng v dn

lnh , my nn hot ng bnh thng.

4.6. VN HNH H THNG LNH

1. Cng tc chun b. Cng tc chun b gm cc bc sau:

Kim tra in p ngun khng c sai lch so vi nh mc 5%.

VU 400360


Theo di dng in my nn. Dng in khng c qu ln so vi quy nh.

Nu dng in ln qu th ta ng van chn ht li.

T t m van chn ht ra cho n khi dng in khng tng qu mc th thi.

Bt cng tc SWs sang v tr ON cp dch cho dn lnh.

Kim tra cc thng s p sut trng h thng.

p sut ngng t < 16 kg/cm2.

p sut du ( )5.25,1 += hd PP kg/cm2. p sut ht < 1,5 kg/cm2.

Ghi li ton b cc thng s hot ng ca h thng bao gm: in p ngun,

dng in cc thit b, nhit v p sut du, nhit v p sut ht, nhit v p

sut nn, nhit bung lnh, bay hi.

3. Dng my. Dng my c 3 trng hp l dng my s c v dng my bnh thng.

Dng my bnh thng:

+ Nhn cng tc SW2 v v tr OFF cho gas chy v ht bnh cha cao p.

+ Khi p sut ht xung thp qu mc lm cho rle p sut ht mt in v

my nn ngng hot ng.

+ ng van chn ht li.

+ Nhn cng tc SW1 sang v tr OFF ngng qut dn ngng v qut dn

lnh.

+ ng cc ptomt ca cc thit b li.

Dng my s c.

+ Khi c s c khn cp cn tin hnh ngay lp tc:

+ Nhn cc cng tc SW1 v SW2 v v tr OFF dng my.

+ Tt cc aptomat tng ca t in li.

+ ng van chn ht li.

+ Tm nguyn nhn x l.

Dng my lu di.


Dng my lu di cn tin hnh ht nhiu ln ht kit mi cht trong dn

lnhv a v bnh cha cao p.

Sau khi tin hnh dng my, tt aptomat ngun v kho t in.

4.6. BO DNG H THNG.

1. Bo dng my nn.

Vic bo dng my nn l cc k quan trng cho h thng hot ng c tt,

bn v hiu qu lm vic cao nht.

My lnh d xy ra s c trong ba thi k: Thi k ban khi mi chy th v

thi k xy ra cc hao mn cc chi tit my.

C sau 6000 gi th phi i tu my mt ln. D my t chy th cng phi 1 nm

i tu my mt ln.

Cc my dng lu ngy trc khi chy phi tin hnh kim tra

Cng tc i tu gm:

Kim tra kn v tnh trng cc van x, van ht ca my nn.

Kim tra bn trong my nn, tnh trng du, chi tit my c b hoen g, lau chi

cc chi tit. Trong thi k i tu phi tho cc chi tit, lau chi v thay du m.

+ Kim tra du bn trong ccte qua ca quan st du. Nu thy bt kim loi

mu vng, cn bn th phi kim tra nguyn nhn.

+ Kim tra mc mi mn ca cc thit b nh trc khuu, cc m kn, vng

bc, pittong, vng gng so vi cc kch thc tiu chun. Khi mn qu mc cho

php th phi thay th ci mi.

Th tc ng ca cc thit b iu khin HP, OP,WP, LP v b phn cp du.

Lau chi v sinh b lc ht my nn.

V sinh trong ng c.

Cng tc bo dng nh k: theo quy nh c 72 n 100 gi lm vic u tin

phi tin hnh thay du my nn. Trong 5 ln u tin phi thay du hon ton.

1. Bo dng thit b ngng t. Bo dng thit b ngng t gm cc bc sau:

V sinh b mt trao i nhit.

X du tch t bn trong thit b.


Bo dng cn chnh qut gii nhit.

Sn sa bn ngoi.

Sa cha thay th thit b in, cc thit b an ton v iu khin lin quan.

2. Bo dng thit b bay hi. X bng dn lnh: Khi bng bm trn dn lnh nhiu s lm tng nhit tr ca

dn lnh, dng khng kh qua dn b tc, gim lu lng gi, trong mt s trng

hp tc qut v mt qut khng th quay lm chy ng c. V vy phi thng

xuyn x bng.

Bo dng dn lnh:

V sinh dn trao i nhit, mun vy cn ngng h thng hon ton, kh

dn lnh v dng chi qut sch. Nu khng c cn phi ra bng nc.

V sinh mng thot nc dn lnh.


KT LUN

Sau mt thi gian thc hin n ny ti hon thnh n ca mnh. Qua

qu trnh tnh ton thit k ti rt ra mt s nhn xt sau:

u im ca n:

vn dng c cc kin thc ca mt s mn hc vo qu trnh tnh ton v

thit k qua y cng cng c thm kin thc phc v cho qu trnh cng tc sau ny

n cng gii quyt c v a ra phng php xy dng nhanh cc kho

lnh c dung tch va v nh p ng nhu cu hin nay

Nhc im:

Vic tnh ton tn tht nhit v chn h thng lnh cn mang tnh l thuyt,

cha p dng c cc cng ngh mi dn n cc thng s mang tnh c lng

cha st thc.


TI LIU THAM KHO

[1]. inh Vn Thun - V Ch Chnh. H thng my v thit b lnh

Nh xut bn khoa hc k thut 2005.

[2]. Hong nh Tn, Bi Hi. Bi tp K thut nhit. Nh xut bn i hc Bch

khoa Thnh ph H Ch Minh, nm 1993

[3]. Nguyn c Li, Phm Vn Ty. K thut lnh c s. Nh xut bn Gio Dc,

nm 2002.

[4] Nguyn c Li. Mi cht lnh. Nh xut bn Gio Dc, nm 1998.

[5]. Nguyn c Li, Phm Vn Ty. Bi tp K thut lnh. Nh xut bn Gio

Dc, nm 1998

[6] Nguyn c Li. Hng dn thit k h thng lnh. Nh xut bn Khoa hc v

K thut, nm 2002.

[7]. Nguyn c Li. T ng ha h thng lnh. Nh xut bn Gio Dc,

nm 2001.

[9]. Trn Vn Lch. Lp t v vn hnh my lnh Nh xut bn H Ni, nm 2005

Tinh Toan Lap Dat Kho Bao Quan Dong Suc Chua 400 Tan

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