Nghiên cứu tính toán thiết kế buồng đốt trấu hoá khí quy mô nhỏ sử

Nghiên cứu tính toán thiết kế buồng đốt trấu hoá khí quy mô nhỏ sử

NGHIEN COfU - TRAO DOI
NGHlfiN CUtJ TINH T O A N THIET KE BUONG DOT TRAU H O A KHI QUY JViO NHO
SU" DUNG CHO H O GIA DINH N 6 N G T H O N
RESEARCH AND DESIGNING A GASIFIER STOVE WHICH USE IN THE RURAL FAMILES
TS. Bui Trung Thanh', TS. Nguyen Van Tuyen^ KS. Le Dinh Nhat Hoai^
'Khoa Cdng nghe Nhiet lanh Dai hpe Cdng nghiep Thinh phd Hd Chi Minh
^Bp mdn Cdng nghe Nhiet lanh Dai hpc Bach khoa Thinh phd Hd Chi Minh
^Trung t i m R&D Tech Dai hpe Cdng nghiep Thinh phd Hd Chi Minh
TOM TAT
Trau thdi Id mdt loai chdt ddt thdn thudc vdi ngUdi ddn ndng thdn d Viet Nam. Ta thudng nhin thdy tUng
dong trau Idn sau cdc nhd mdy xay xdt. Thdng thudng trau dUde sU dung bang cdch dot chay trUc tiep trong cdc Id
ddt truyen thdngdecdp nhiet diingcho ndu an tronggia dinh, nunggqch, sdy ndngsdn.. .PhUdngphdp dot trau chay
trUc tiip trongbuongdot tdn tai nhieu nhUdc diem.
Trongbdi bdo ndy, tdcgid trinh bdy phUdngphdp dot trau mdi bang cdch chuyen doi nhien lieu ran thdnh
khi hod vd Ungdungnguyen ly khi hod ndy de tinh todn thiit ke mdt loai buongdit trau hod khi nguyen lydot nghich
quy md nho, dUdc Ung dungdUdi dang bip dun tronggia dinh ndng thdn nhdm khae phue ede nhUde diem cua loai
hep dun truyin thdng.
Bip cd cdc thdng so ccf bdn:
- Dudngkinh buongchUa trau: 250mm
- Chieu cao buongchUa trduphdn Ung. 600 mm
- The tich buongphdn Ung: 0,03m3
- Jongchiiu cao cua b^ dun: 900mm
- Cdngsudtqmt: 65W
- Cdng sudt cda buong dot: 6,4kW.
ABSTRACT
Rice husk is a kind ofbiomass which is very much common in the rural re^on of Vietnam. We can see piles
of rice husk at the back of the rice mill Normaly rice husk uses as fuel to cook in families, brick furnaces and grain
dryers.
Rice hud: is directly burned in the traditional stoves. The direct burning method has disadvantage.
This paper present a new rice husk burned method. Rice husk converts into carbon monoxide and hydrogen
by reacting the raw material with a controlled amount of oxygen. This new called gasification method
It is based on nutrition demand of each mealfor members in the family, the author calculates and designs a
newgasfier stove which uses rice husks as fuel The parameter of the stove such as:
- The diameter of combustion: 250mm
- Heigft of reaction combustion: 600 mm
- The volume of reaction volume: 0,03m3
- The toted ofheight of the stove: 900mm
- Capacity of fan: 65W
^^
- Capacity of combustion: 6,4kW.
T< n r i T f r - r i i r u f ^ri^j
NAM
*l*
Sd 7 (Thing 7 nam 2012)
NGHIEN ClJfU - TRAO D O I
vi cd th^ cap nhi^t cho cic muc dich khic dU6i
dang cip nhitl quy md nhd d khu vUc ndng thon.
I.DAT VAN DE
Trau thii td cic nhi may xay xit li mpt
loai chat ddt rai quen thudc vi gan gui vdi ngUdi
ndng dan ndi chung trong ci nuue, die bivl li
ndng din d vung ddng bing sdng ("Uu Long. Trau
chu yeu dupe sd dyng de nau in d gia dinh, mdt
sd thi dupe dung de ddt nung gach d cic xudng
sin xuat gach ngdi, sd il khic ihi dUpc diing trong
miia say ndng san, nhieu noi thi phii ddt bd do ed
qui nhieu.
2.n0I,lfiU VA PHL/ONG P H A P
2.1.Gidi thi^u bep dun truyen thdng
Cae ki^u bep dun triu truyen thdng co
cau true lUPng ddi dPn gian. de che tao, gii thanh
thap, ngUdi dan cd the tU lim dUpc, tuy nhien cac
loai bep dun niy khi dun nau ludn sinh nhieu
khdi kem theo, hi?u suit cip nhi^t thap. Trong
Trau li ngudn chit ddt co sin ngay tai cic qui trinh dun niu thUdng xuyen phai cd ngUcfi
diem xay \al gao tgi cic ling que d ndng thdn, einh gidi vi phii cap triu vio budng ddt.
re tien. Trau la loai nhien li^u de chay, khi ning
Do cich cap trau vio budng ddt li dang
sinh nhi?t tdt. 1kg triu khi ddt ed the sinh ra nhi^l
lUPng khoing 3000 keal, bing 30% nhi?t lUpng hd nen thUe pham trong dun niu ludn bj nhi^m
dau DO va 25% -27 % gas LPG, nhUng gii thi lai bui trau vi cd miii khdi. Hinhl. Gidi thieu mot
sd kieu bep ddt trau ehiy trUe tiep thUdng gap d
thap hpn tii 20 lan den 25 lan.
ndng thdn vimg Ddng bang sdng CUu Long.
y
Ddi vdi trau lam chat dot dun nau trong
gia dinh thi tU trUde den nay, ngUdi ta chi cd mdt
each duy nhat la ddt trau chiy trUc tiep trong cac
^.^..iM
bep dun truyen thong. Thdi gian gan day tai mpt
so dia phuong eua Ddng bang sdng Ciiu Long,
ngUdi ta ep trau thinh eae thanh cui triu de tien
dung hpn trong van chuyen va ton trijf de dun
nau, tuy nhien viec ep thanh thanh cui lai lam
chat dot re tien nay trd nen dit tien hon, nhieu
ngUdi din khd tiep can sd dung loai nhien lieu
mdi niy. Ngoii ra, viec dau tU mdt may ep trau
thinh thanh cui eung rat dit tien, dong thdi edn
phai ke den dp tin cay ciia mdt sd cum eiia miy ep Hinh 2 Cut trtiu va than trau ep vien diing cho
dim chUa cao, thudng xuyen hU hdng vit ep.
dun truyen thong.
Trong bai bao niy, tic gii trinh biy
phUPng phap dot trau mdi bing each chuyen ddi
nhien lieu ran thanh khi hoi vi Ung dung nguyen
ly khi hoa nay de tinh toin thiet ke mdt loai budng
dot trau hoa khi quy md nhd dUpe Ung dung dUdi
dang bep dun gia dinh, nham khic phue cic
nhupe diem cua loai bep dun truyen thdng, ning
cao khi nang tien dung trong sit dung ngudn trau
thii d ndng thdn phue vu viec nau in hing ngiy
TAP CHf CO KHl VIET NAM
ii
2.2 Tim hieu ve trau
Trau la Icfp v6 ngoai cung cua hat liia ^
duoc tach ra trong qua trinh xay xat. Mot kilogram Ilia khi xay xat co the cho ra 200- 230gto
trau (chiem khoang 20%-23% tong khoi Um
hat Ilia, c6n lai khoing 77-80% la thanh phan g?o,
tamvacam)[ll
S6 7 (Thang 7 nam 2012)
NGHIEN CtfU - TRAO D 6 I
H
1" -
Hinh S.Cdc sdn plidm thu dUdc tit xay Ida
Bdng 1: Thdnh plidn cua trd'u (3}
Kich c8
Nhiet tri
2,5 - 5 m m
12,5 - 14 mj/kg
Thinh phan hoa hoc (% KL)
c,„
H,„
35,77
5,06
Trong vd trau chUa khoing 75% chat hiiu
ca dl bay hPi, chung se chiy trong q u i trinh ddt
vi khoang 25% cdn lai chuyen thinh tro 12]. Chat
hiiu eP ehiia ehu yeu trong trau cellulose, lignin v i
hemi - cellulose (90%), ngoii ra cdn cd them thanh
phan khic nhU hpp chat nito v i vdcP. Chat Lignin
chiem khoing 25-30% va cellulose chiem khoing
35-40%t7]. Cic chat hflu eP eua trau la cic mach
polycarbohydrat rat dii nen hau het cic loii sinh
vat khdng the sd dung tnic tiep dupe, nhUng cic
thinh phan nay lai rat d l chay do viy trau dUpc
dimg lim chat ddt.
Sau khi dot, trong tro trau cd chUa tren 80%
la silic oxyt, khoang 15 den 20% tro. silie oxyt li
thanh phan cd the dUpe tai sU dung trong rat nhieu
linh vUc khic nhau trong nginh Vat lieu xiy dUng
[5]
s„.
8,08
0,,31,6
N,„
8,32
w,.
\
8,05
3,12
Trau cd khdi lUpng the tieh (pb) 100 -r
120kg/m3. Nhiet tri thap khoang 3000 kcal/kg khi
chay 11] [3]
De dot chay hoan toan 1 kg trau trong dieu
kien binh thudng, ngudi ta phai cung cap cho trau
tU 4,3 -^ 4,7kg khdng khi [l]t6]
2.3 Cac phan ling hda hoc xay ra trong q u i trinh
nhiet phan hda khi
Trong mdt budng ddt hda khi, cic nhien
lieu ehda carbon trai qua nhieu qui trinh khae
nhau:
Qui trinh nhiet phin xiy ra khi nhien lieu
dupe nung ndng len, chat dl bay hoi thoit ra vi
than dupc giii phdng ra. Qui trinh niy phu thude
vao tinh chat, thinh phan va cau true cua nhien
lieu, sau dd se trii qua eic phan Ung khi hda.
Q u i trinh dot sinh ra cac sin pham dl bay hoi
v i than d^ sinh ra khi CO^ v i CO.
Hinh 4. Vd trau
Qua trinh khi hda xiy ra khi than phan Ung vdi
COj va nUdc de sinh ra CO va H^ theo phan Ung:
C + HO->H +CO
'^
erf KHf VTET NAM
•t*
Sd 7 (Thang 7 nam 2012)
NGHIEN COTU - TRAO DC!)I
Ngoii ra, khi CO dat ean bing rat nhanh
khi nd phan Ung vdi nUde d nhi^t dp trong budng
dot hda khi. Dieu nay lim can bing ndng dp ciia
khi CO, hdi nUdc, C 0 2 va H2.
2.4. Nguyen 1^ ddt trau h o i khi
2.3.1. Buong d6t nguyen ly thuan
Nguyen ly ki^u ddt thuan (Downdraft
gasifier), khdng khi cap tU tren xuong vi di ciing
chi^u vdi chi^u djch chuyen cua trau nhi^n li^u.
Trong nguyen ly niy hie in tao ra se di theo d6ng
khi tfl trdn xudng, ludng khi chinh se di qua viing
oxy hda eiia budng ddt hda khi, hie in bi chay va
keft qud li vi?e chiy sach. (ias dflpc tao ra til qui
trinh h o i khi se dUpc ISy tfl day budng dot. Nhit
vay ddi vdi budng ddt nguyin ly thu^n, nhignli^
se dupe nap lien tyc tai dinh cua budng dot.TrSn
dudng di xudng, cic thinh phin cua trau nhien
(1) li^u li^u phii di qua vimg nhi?t phin (tang than)
v i dupc chuyen thinh cic khi H2,CO.C02 va
(2) CH4, cic thinh phin khi lao ra nay se tuy thupc
vao nhi^t dp cua vung ndng v i thdi gian ma hd
(3) hie in di qua.
Ve bin chit, mpt sd lUpng ban ehe oxy
hoac khdng khi dUpe dUa vio budng ddt hda khi
de cho phep mpt sd cie nhi^n li^u hflu cP dupc
ddt chiy de sin xuat CO va ning lUpng dc cic
phin Ung lien tyc sinh ra hydro v i bd sung C 0 2
I5|
Cdc phdn ting toa nhiit:
Phin Ung chiy:
C + O^ -> COj - 401,9 kj/mol
Phin Ung oxy hda khdng hoan toin;
C + 1 / 2 0 . - ^ CO
Phan Ung Metan hda:
C + 2H,->CH^
Phan Ung luin phien khi - nUde:
COj + Hj ^ CO + Rp - 42,3 kJ/mol
Phin flng Metan hda tU CO:
CO+3H, ^ C H ^ + H p - 205,9 kJ/mol
(4)
(5)
Cdc phdn Ung thu nhiet
Phin flng C va hoi:
C + Hp -> CO + H^ + 122,6 kJ/mol
Phan Ung Boudouard
C-h 0 0 ^ ^ 2 0 0 + 1 6 4 , 9 kJ/mol
- Kha nang tao ra ddng khi hda khong
chUa hie in (tar-free) se thugin Ipi cho vi^c cung
cap nhien lieu khi h o i cho cac ddng cO no (ner
flng dung cap nhien lieu cho ddng cP no sau kh
d i lim ngupi, Ipe va tieh tap chat theo tieu chuan)
(6)
(7)
Cac phuong trinh (6), (7) li cac phan Ung
chinh cua q u i trinh khfl, cho thay ring nhi^t
Iflpng se giim xudng do phai cung cap nhi^t cho
p h i n flng nen nhiet dp cua ddng khi hda se giim
dan trong sudt qua trinh khfl. PhUPng trinh(4)
dupe gpi li phan flng can bang khi - nfldc (phan
Ung luan phien khi - nfldc).
Ve mat ly thuyet, doi vdi mdi nhi^t dp, ti
sd gifla s i n pham cua CO v i H ^ v i san pham
cua CO^ v i Hj li co dinh va bing gia tri can bang
khi - nude khdng ddi. Trong thUe te, t h i n h phan
cin bang cua khi se chi dat dUpc trong trUdng
hpp tdc dp p h i n flng va thdi gian cho p h i n flng
ladu[5].
TAP CHf CO KHf VIET NAM
Loai budng ddt niy cd Uu diem:
•
1
M.
__
1
1
a
1
1
1
I|
m
l-CiiaciipnhiinlifK
2-Vung sdy.
3- Viing diilngcit! ~|
4- Ddy Id;
5'Khdng khi vim
6-Viing kh^
7-Ghi Id;
8-Gasra;
9- Phin chUa tro:
10- Trau.
11-Vimg nhietphtK
12-Viing diHamnH
Hinh 5. Buong dot hda khi nguyen ly thudn ddng[5i
- Kha nang lim sach hac in cao cd the dat
70- 80% [5] Do lupng hac in da bi chay het khi di
qua viing chay.
I
- Q u i trinh hinh t h i n h khi dpn gian *
Tuy nhien loai budng ddt nay cd n h #
di^m:
Sd 7 (Thing 7 nam
2012)-
NGHIEN COfU - TRAO D6\
- Kha nang hda khi cho mdt sd nhien lieu
m i khdng qua xU li trfldc se kem. Dac biet li cie
nhidn lieu cd mat dp thap se lim phit sinh eic van
de ve ddng ehiy va tdn i p q u i nhieu.
sU truyen nhi?t ddi Iflu cUdng bfle va bfle xa
tU nhflng vimg thap hon d ben dfldi. Hac in
(tar) v i eic chat de chay se cung dich ehuyen
theo ddng gas. Tro dupe lay ra ngoii tfl diy eua
budng dot hda khi. Budng ddt nay cd Uu diem
- Loai budng ddt niy cd h i m lUpng tro cao
hPn budng dot theo kieu nghich.
. Dpn giin, gia che tao thap.
- Budng dot loai niy cd hieu suat thap hon
budng dot kieu nghich do thieu trao ddi nhiet ben
trong ciing nhU gii tri nhiet cua ddng khi hda.
- Khi nang chiy eiia tro cao.
- Hi^u suat sinh nhiet eua thiet bi cao.
- Vdi loai budng dot niy yeu cau can thiet
phai duy tri nhiet dp ddng deu cao tren tilt dien
chiy-
Cd k h i nang hoat ddng vdi nhieu
i^^^ nguyen lieu khic nhau (mun cUa, vd ngu
cdc...).
- Yeu cau ham lupng i m trong nhien lieu
dUa vao khi h o i phai thap
^^i ^^^
- Khi thoat ra d efla budng dot hda khi cd
nhiet dp cao, can ed he thdng thu hdi nhiet.
Loai buong dot niy tdn t^i mdt sd nhupe
diem nhU-
- Loai budng dot niy cdn tU 4 -^ 7% ham
lupng carbon khdng chuyen ddi het.
- Cie Id phan phdi khi d l bi oxy hda, v i
cd the bi bit kin do eac keo nhfla, tar di qua. Do
vay vdi loai budng dot niy can phai lap dat thiet
bi phan phdi khi dang rdi de d l ding thay the va
lam ve sinh dupe
2.3.2. Buong dot nguyen Iy nghich
Budng dot nguyen ly nghich edn gpi
(budng dot Updraught gasifier). Ddi vdi loai
budng dot nay thi cic hat nguyen lieu chay chu
yeu d phan diy buong dot.
*
,
. ^ 6 the sfl dung nguyen li?u smh khdi
^^^^^ ^^ ^^ ^^^^^^ ph^n vd cP cao [5]
' Theo [5] gas dflpc tao ra tfl loai budng
ddt nay cd chfla tfl 10 -^ 25% h i e in ( t i n h theo
khdi lupng)
1-Ola c^p nhiSn b^u;
2-Gas ra;
- Loai budng dot nay khuyen cio Iflu y
den vile loai bd hac in neu gas tao ra dflpe dung
trong viec cap nhien lieu cho ddng ed nd.
2.3.3 Budng ddt cd ddng khi cheo nhau
Hinh 6. Buong dot hoa khi nguyen ly nghich - 15U2]
'
Khdng khi vao budng ddt d phia dfldi
va gas t h o i t ra d phia tren. Can d ghi budng
dot c i c phan flng chiy xiy ra v i cic p h i n Ung
*niy giam dan theo chieu cao ciia budng dot. 6
eac phan tren eua budng ddt hda khi xiy ra sfl
tddt ndng va nhiet p h i n nguyen lieu v i o nhd
Ddi vdi loai niy, thi ddng khi cap cho
qua trinh chay trau trong budng dot di ngang
vdi chieu dich ehuyen cua cdt trau nhiln lieu.
Tai vung oxy hda trong loai budng dot n i y cd
nhiet dp khi hda rat cao (cd the >1500''C[5]. Do
vay vat lieu che tao loai budng ddt ylu cau chiu
dUPe nhiet dd cao hon hai loai tren.
TAP CHf C O KHf VIET NAM
•t*
Sd 7 (Thing 7 nam 2012)
NGHIEN CUU - TRAO D O I
3.1 Xic dinh nhiet lU^ng cua buong dot cia
cung cip 6i nau in trong ngiy
3.1.1. Tinh todn ndng lUdng cdn cung cap cho
ngtfdi hdng ngdy
Ca sd tinh toan thiet k^ dflpe dUavaonhu
eau cin cung cip ning Iflpng thdng qua vile dun
niu thdc pham, dun nUdc uong trong mdi bu6i
niu trong hp gia dinh.
*
Thdng th Udng theo khao sit gia dinh nong
H);j/i 7. Budng dot hda khi c6 ddng khi cheo nhau [Sj
thdn trung binh ed 6 ngfldi vdi cip dp tudi phan
I- Citii flip nhfn li(u, 2- Viing sdy,
3- Vung chiing nil.
bd nhu sau:
4- Viing khA
+ Hai ngUdi dp tudi tfl 30 - 60
5- Gas ra.
6- Tro thay.
+ Hai ngfldi dp tudi tfl 18 - 30
7- GftJ W,
+ Hai ngfldi cd dp tudi 10-18
i- Viing chila tro.
9-Ddy Id:
Thdng thfldng trung binh cfl mdi cap tuoi
liet ke d tren li mpt nam va mpt nfl.
10- Khdng khi vdo.
Budng ddt niy cd flu diem:
Tat ca mpi ngUdi deu thudc dang lao dpng
trung binh. Theo[4l nhu cau dinh dUdng kien
- Budng dot nay ed the van hinh d qui md nhd. nghi cho ngfldi Vi^t Nam" thi nhu cau nang lUdng
- Viec lim sach gas rat don giin (chi can phai cung cap nhfl sau:
ed mdt bd cyclone).
- Nam tfl 30-60 tudi can 2700 kcalo/ngay.
Tuy nhien budng ddt nay cd nhUpe diem li:
Viy nhiet lUpng: 5400kcalo
- Khi ning ehuyen ddi hac in thap
- Nfl tfl 30-60 tudi can: 2500 kcalo/ngiy.
Viy nhiet lUpng can 5000kealo/ngay
- Yeu eau nhiln lieu cap vio vio ed chat
Iflpng cao [5].
- Nam tfl 10-20 tudi can 2200 kcalo/ngay.
Viy nhi^t lUdng can: 4400 kcalo/ngay
3. KET QUA TfNH TOAN THIET KE
Tdng edng nhiet Ifldng can cap tU cac buoi
Tren cP sd phan tich thinh phan cua Triu an li 14800 kcalo/ngiy
thai, cung nhU dl' cap ve eae phan Ung xiy ra
trong qua trinh dot trau hoi khi vi eac nguyen ly
Ta di tinh nhiet Ifldng cho tflng lan siJ
hoi khi, tic gii Ifla chpn nguyin ly hoa khi kieu dung budng dot trau hoa khi de dun nau an trong
nghich de tinh toin thiet ke budng ddt cip nhiet gia dinh trong moi buoi an.
sfl dung trong dun nau cho hp gia dinh ndng thdn
theo hfldng nghien cflu.
TAP CHI CO KHf VIET NAM
So 7 (Thing 7 nam 2012)_
NGHIEN ClJfU - TRAO D 6 |
3.1.2.Tinh liidngnUdc uong trong 1 buoi
T = 10/60 - Thdi gian nau nfldc, h (dU kien
nau trong 10 phut)
Theo [4]cfl 10kg thi' trpng can 0,4 kg
nUde/ ngay. G i i sfl trpng Ifldng trung binh mdi
ngUdi Idn la 55kg. Gia dinh gdm 4 ngUdi Idn vdi
tong trpng lUpng la 220kg vi tdng trpng lUpng 2
ngUdi nhd 80kg (lay trung binh mdi ngfldi 40kg).
Nhfl vay ta tinh dflpe lUdng nUde can eung ci'p
cho gia dinh trong 1 ngay se l i 12 lit. Ta phin bd
mdi buoi nau 6 lit nfldc v i dUpc tinh toin nhiet
Iflpng dun nau nhU sau:
3.1.2.1. Nhiet lUdngcan denau nUdc
3.1.3. Nhiet lUdng cdn thiit denau cdm
Sfl dung cdng thUe
Q,^:!LiJi.'-°;'-''-,|4S.6kc.ll.
T
]2_
60
Trong dd:
Ta gii sfl nhiet dp ban dau eua nude va cae
thUc pham bang nhiet dp mdi trUdng t" = 28"C.
Q. - Nhiet Iflpng can thiet, kcal/h;
m = 1,2- Khdi lUPng gao can nau, kg; (can
a. Nhiet Ifldng can thiet de lam ndng noi
ni'u 1,2 kg gao cho 6 ngfldi an)
C=;0,43keal/kg"C - Nhiet dung rieng eua
SU dung cdng thUc:
„
m,. cAt
10.13":
gao [7]
At =100 - 28 =72- dd chinh lech nhiet do
=Ii:Jkcalh
trUde vi sau khi nau, "C;
T = 15/60- thdi gian nau edm,h;
Trong dd:
(du kien nau trong 15 phut)
Q ^ - nhiet Ifldng can thiet, kcal/h;
m^^ =1- khdi lUdng ndi, kg;
c = 0,13 (kcal/kg*'e) - Nhiet dung rieng eua
vat lieu che tao ndi
At = 100 - 28 =72 - dp chinh lech nhiet dp
trfldc v i sau khi nau, °C
'
X = 5/60 - thdi gian lim ndng ndi. h;
•: (dfl kien l i m ndng ndi nau trong 5 phut)
3 b. Nhiet Ifldng can thiet de nau nfldc
Q
r
r
10
60
3.1.4. Nhiet lUdngcdn denau mon thit
Sfl dung cdng thflc
Q , = - ^ ^ ^ = —j^=;SS.8kcalh
Trong dd:
Qii^ - nhiet lUpng can thiet, kcal/h
m^^ = 1kg - khoi lUpng thit can nau, kg
c = 0,9 keal/l^C - nhiet dung rilng eua thit [7]
Trong do:
At =100 - 28 = 72 - dp chenh lech nhiet dp
:;
s.
Q^ - nhiet Iflpng can thiet, kcal/h
trUdc v i sau khi nau, °C;
m^ =6 - khdi Ifldng nfldc can nau, kg
T = 10/60- thdi gian nau, h;
c = 1 - nhi^t dung rieng cua nfldc, kcal/kg°C
(dfl kien nau trong 10 phflt)
At =100 - 28 = 72- Dp chinh leeh nhiet dp
:rUdc va sau khi nau,''C;
__ ^TXS^ui-cri
i^of v r e x NAM
V
Sd 7 (Thing 7 nam 2012)
NGHIEN CtfU-TRAOeOi
j
3.1.5 Nhiet liiging can de niiu m6n ran
3.2.2. Difdng kinh bu6ng dot
Ap dyng cong thilc:
Dudng Icinh buong dot In • khi la doi
kinh mat c4t ngang cuaflngtry noi irau bj chiyi
hoa khi. Duemg kfnh buong dot co the dU()ct|[
theo |6|:
Q_ = !!ll£rl = L_L^=60:.6kcal h
10
60
T.ongd6:
Q. S .
V B
PMl.0.254,m)
V 120
Q^-nhiet IU0ng can thiel, kcal/h;
Trong do:
*
m =l,5-kh6i luong rau can n3u, kg
c = 0,93kcal/kg"C - Nhiet dung riSng ciia
D-du6ng kinh ciia buong dot, m
rau, 17|
G„ = 6,1 - luong nhien li^u can thift, kg/h'
At =100 - 28 = 72- Dp chenh lech nhiet dp
B '= 110-210- toe dp hoa khi riSng, k
trudc va sau khi nau,"Ci
m'h. Theo [2) ta chpn B= 120kg/m'h
Xa chpn dUong kinh buong hoa khi D:
T = 10/60 - thdi gian nau, h; (dU kien nau
trong 10 phut).
0,250m
Tong nhiet lUong can thiet sil dung cho nau an 32.3 Chieu cao cua buong dot
Q„.= (Q„o + Q, + Q, + Q, +Q.) = 3844.3 kcal/gid
Chieu cao cua buong dot hoa khi la toi^
Theo [6] nhiet luong can nau khi tinh Uj^jng ^^^-i, ,(j ^^„Yt den day buong dothoaUii
toan can nhan them he so k do t6n that trong qua (j^'n mat ghi). Chieu cao dUpc xac dinh tion[
trinh nau va do each bo tri luc nau khong lien tuc. kh^j^g ,hdi gian buong dot hoal dpng khi n
Chpn k= 1,45. Vay nhiet lupng ciia be'p cung cap ^ ^ , |j„ „|,i^„ ,j^^
cho mpt lan nau la: 5500 kcal/gid hay cpng suat
ciia bep la: 6,4kW.
j ^ ^ G . T ^ 120.0,5
K
100
' "
3.2 Tinh toan thiet ke bep dot
.r.
...
3.2.1 Tinh liidng trau cdn tiap vdo buone dot hod
..,
*
T. .. . I.
^ .-,...,, .
^
Ta tinh lupng trau can thiet la lupng trau
can cung cap cho bep dot cho moi lan dot: Si
dung cong thilc tinh [6]
G=-2s_=J!^=6,Uh
H\-,4, 3000.0J
^
Trong dd:
G„-lupng trau can cung cap, kg/h
Q„=5500-nhiet lupng can denau, kcal/h
q„, = 3000 - nhiet tri ciia trau, kcal/kg
\ = 30-hieu suat ciia bep khi nau %.
TAP CHl CO KHl V I £ T NAM •
n L--.
. U - 3^
H-chieu cao cua buong dot, m;
B= 120- Hf so khi hoa rieng, kg/m%!
T =0,5-thdi gian yeu cau chayhettrau.lt
Pj, =100-khoi lUpngthetich traudSl^
thai tU nhien, kg/m'.
3.2.4 T6c do chiy
Tdc dp chay la thdi gian can thift dlviuj
chay di chuyen xudng phia dudi, dUdc tinh tbw
cong thiic:
H 0,6
fml
^"T"o^"''^ T
^
'
'^
Trong dd:
S6 7 (Thang 7 nSm 2012)_
NGHIEN COU-TRAO Ddi
H = 0,6 - chilu cao eiia budng ddt, m
^i
T = 0,5 - thdi gian dot chay het trau, h;
ri-i
Nhu viy tde dd di chuyen khi chay hoa khi
J z = 0,03cm/s
.2.5 LUdng khong khi cdn thiit cho qud trinh khi
od
Theo [6], ton that dflpc tinh toin
,
y ''i /, n ^
IT/-.
h, = ( , - ^ . ( l + p . t ) , m m H p
°
khi
.
i.
V , . .s^
,, .
,, ,
LUdng khone khi cung cap cho buong dot
1
11.
,. - « , V ,
. , , ,, ,
nay lUdng khong khi can thiet cho qua trmh khi
/. , „ °
°
^
oa),m^/h:
a.ij^^.A _ 0,35.6,1-4,5 _g^3^_Q QQ22it^\^s
u
n^
1,2
.,
:: rong do:
a = 0 , 3 5 - H l s d q u y d d i k h i h o i k h i G =6,1upng trau can thiet, kg/h
'
A= 4,5- Iflpng khdng khi khi dot trau d
tieu kiln binh thfldng
,,
,,
,
,.
V
,
1 1
P - he so nhiet eua khi, p = ^ ^ ^ - ;
Tieu chuin Reynolds dupe xic dinh:
p = 1,2 - khdi luong rieng cua khdng khi,
,
Re=^^,
u
:':g/m\
Nhu viy gii tri Q dflpc hieu li Iflu Iflpng
•^:ua quat cap khi vio buong dot.
V
v^ - van toe dong khi qua Ipp trau , m/s;
C - h i so trd Iflc eua Idp nhien lieu, C pbu
,, . . . - .• r,'
iJ
thuoe vao chuan so Reynolds
" .
L--.»-L- .
. L - ^ . L - i L'U • o,t - nhiet dp ben trong thiet bl khi hoa, "C.
°
Vdi nhiln lieu la trau cd nhiet dp ehiy
chiy trong pham vi tfl 700" C -^ 1400"C, eung vdi
he sd trao ddi nhiet ddi lUu tU nhien eua khdng
\diia = 0.2 -H 0,5) [6]. Ta ehpn tl = 1050°C.
Trong dd:
d - dudng kinh budng tao khi, m;
u - dp nhdt ddng hpc cua ddng khi, mVs;
V - van tdc ddng khi, m/s;
i.2.6 Van toe khidi qua Idp trau
Van tdc cua ddng khi di qua Idp trau trong
^ua trinh h o i khi.
Q
g
- ^^^ITi^
"TTTTT^^^
=4,4cm/s
.
^ . 3 6 0 0 ^ ^ - ^ 3600
4
4
Irong dd:
Tra bang dp nhdt ddng hpc trong cie sach
chuyen nginh, d nhiet dp 1050''C, ta tim dflpc dp
^^^^ d5ng hp^ ^fla khi u = 185,7.10* m=/s.
• '
0,058.0,250
,
Re=-:
^--=78,1>7
185,7.10'
V - Van tdc cua khong khi xuyen qua Idp
nhien lieu,cm/s;
Q^ - LUU luong khong khi cSn thiet cho
qua trinh khi hoa, mVh;
<
D - Dudng kinh budng ddt, m.
i; =
+
|
" -555
'
Re
Re"'
78,1 78,1""'
Vay trd lUc khi di qua Idp nhien lieu trong
thiet bi khi hda la:
3.2.7Xac dinh tSn thdt buong dot
Vi Re > 7 ( che dp roi) nen ta cd:
0 048'
h = 55,5 ^ ^ i ^ (1 +
2
De cd ca sd thiet ke quat cap khi cho
buong ddt, trong pham vi tinh toan ta di xac dinh
tdn that trong budng dot.
. . TAPjC;v;^f<i<rm v i F T N A M
V
1
.1050) =13,5 N/m^
273 + 1050
Sd 7 (Thang 7 nam 2012)
NGHIEN COfU - TRAO DOI
con phii linh dcii tdn that cue bp khi sin,
I h i l i o i d i q u a c a e k h e h ^ p d d i y l d , kenhdl
i m
I
.l.uii; dm thu vi dd md, co 90", vj tri re nhinl
dudng di cua s.in pham khi den chd dunni
d.ic bi?t qua ghi phan pbdi khi (vai trd lin
phun khi) lai chd dit ndi nau tdn that ma si
sin phim khi chay trin dfldng dng den vjtr
pu.iu ,'hi>au,.
sinh nbi|l dung cho nau an. •
,u,i,il)'khi:
3
Ngiy nh^n bii: 28/6/2012
Ngiy phin bi(-n: 04/7/2012
Hinh 8. Bip dot Inui hod kin nguyen ly iighfch
Ngudi phan bien: (iS, TSKH. Tran V3n Phu
Dfla trin cac nguyin ly hoa khi, nhu cau
eung cap nang lUpng thdng qua vile dun nau eic
Tai lieu tham khao:
khau phan thfle an trong gia dinh trong cic buoi
an trong ngiy, tic gii da tinh toin thiet ke dupe
mdt loai bep dot trau hoa khi theo nguyen ly dot
jlj. Bill Trung Ihanh.Thiet ke Id dot gas trau.nloai miy say ndng sin. Co di|n khi hoa nong nil
v('(i van de cdng nghi?p hoa hi?n dai hda nong ngi
nghich eung vdi eac thdng sd ky thuat
& ndng thdn, Nha xuat ban Nong nghi?p thing 1 -1
l2l. Ph?m Hoang LUdng, Cng dung cdng ngh?khi
- Dudngkinh buong chfla trau: 250mm;
sinh khdi cdng suit nhd de sin xuat nang lit(fa^
- Chieu cao budng chfla trau phan Ung: 600 mm;
chi Khoa hpe & cdng ngh^ nhi?t - sd 74/2007
- The tich budng phan Ung: 0,03m';
13]. Nguyen Thanh Quang. Ding The Hiing, ngh.-
- Tdng chieu cao cua bep dun: 900mm;
cflu thiet ko ch^ tgo h? thdng hoa khi than tang-
- Cdng suit quat: 65W;
djnh. lap *.hi cong ngh^ nhicl.so 9, 2007
[4]. Dao thi Yen Phi, nhu can nang lUpng khaupk^^
- Cdng suit eua budng ddt: 6,4k\\'
in hpp ly, Bg mdn dinh. trfldng Dai hpc Y Pham Ng«
Ihijch.
5. THAO LUAN
151. .Ami K. Rajvanshi, Alternative E n e i ^ in #
cultural, vol 11, nimbka agricuhural research Insttut
Cdng suit quat cung cap khi cho budng
,Maharashtra.lndia,1986, pages 83-102
ddt cdn phu thudc nhieu den dfldng dng vi
(6l. Alexis T Belonio, rice husk gas stove handbool
khoang each cung cap khi tU budng h o i khi den
Central Philippine University - 2005
vi tri ddt khi de sinh nhi?t. Ngoai cac tdn thit do
(71. Energy Efficiency Guide for Industry in Asia
ddng khi qua Idp nhien lieu nhU d i tinh d trin thi
www.energyeificiencyasla.org.
TAP CHf C O KHf VIET NAM
•t*
Sd 7 (Thing 7 nam 2012)