Nghiên cứu tính toán thiết kế buồng đốt trấu hoá khí quy mô nhỏ sử dụng cho hội gia đình nông thôn

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 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 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 hod vd Ungdungnguyen ly hod ndy de tinh todn thiit ke mdt loai buongdit trau hod 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 (Thing 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 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 miia say ndng san, nhieu noi thi phii ddt bd 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 thap, ngUdi dan cd the tU lim dUpc, nhien cac loai bep dun niy dun nau ludn sinh nhieu khdi kem theo, hi?u suit cip nhi^t thap Trong Trau li ngudn chit ddt co sin 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, ning Do cich cap trau vio budng ddt li dang sinh nhi?t tdt 1kg triu ddt ed the sinh nhi^l lUPng khoing 3000 keal, bing 30% nhi?t lUpng hd nen thUe pham 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 gia dinh thi tU trUde den nay, ngUdi ta chi cd mdt each nhat la ddt trau chiy trUc tiep 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 cui triu de tien dung hpn van chuyen va ton trijf de dun nau, nhien viec ep thanh cui lai lam chat dot re tien 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 cui eung rat dit tien, dong thdi edn phai ke den dp tin cay ciia mdt sd cum eiia miy ep Hinh 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 hoi vi Ung dung nguyen ly hoa de tinh toin thiet ke mdt loai budng dot trau hoa 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 nang tien dung 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 qua trinh xay xat Mot kilogram Ilia xay xat co the cho 200- 230gto trau (chiem khoang 20%-23% tong khoi Um hat Ilia, c6n lai khoing 77-80% la phan g?o, tamvacam)[ll S6 (Thang nam 2012) NGHIEN CtfU - TRAO D 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 - 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 q u i trinh ddt vi khoang 25% cdn lai chuyen thinh tro 12] Chat hiiu eP ehiia ehu yeu trau cellulose, lignin v i hemi - cellulose (90%), ngoii cdn cd them 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 lai rat d l chay viy trau dUpc dimg lim chat ddt Sau dot, tro trau cd chUa tren 80% la silic oxyt, khoang 15 den 20% tro silie oxyt li phan cd the dUpe tai sU dung rat nhieu linh vUc khic 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 chay 11] [3] De dot chay hoan toan kg trau dieu kien binh thudng, ngudi ta phai cung cap cho trau tU 4,3 -^ 4,7kg khdng [l]t6] 2.3 Cac phan ling hda hoc xay q u i trinh nhiet phan hda Trong mdt budng ddt hda khi, cic nhien lieu ehda carbon trai qua nhieu qui trinh khae nhau: Qui trinh nhiet phin xiy nhien lieu dupe nung ndng len, chat dl bay hoi thoit vi than dupc giii phdng Qui trinh niy phu thude vao tinh chat, thinh phan va cau true cua nhien lieu, sau dd se trii qua eic phan Ung hda Q u i trinh dot sinh cac sin pham dl bay hoi v i than d^ sinh CO^ v i CO Hinh Vd trau Qua trinh hda xiy than phan Ung vdi COj va nUdc de sinh CO va H^ theo phan Ung: C + HO->H +CO '^ erf KHf VTET NAM •t* Sd (Thang nam 2012) NGHIEN COTU - TRAO DC!)I Ngoii ra, CO dat ean bing rat nhanh nd phan Ung vdi nUde d nhi^t dp budng dot hda Dieu lim can bing ndng dp ciia CO, hdi nUdc, C va H2 2.4 Nguyen 1^ ddt trau h o i 2.3.1 Buong d6t nguyen ly thuan Nguyen ly ki^u ddt thuan (Downdraft gasifier), khdng 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 se di theo d6ng tfl trdn xudng, ludng 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 til qui trinh h o i 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 H2,CO.C02 va (2) CH4, cic thinh phin lao se 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 dUpe dUa vio budng ddt hda 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 hydro v i bd sung C I5| Cdc phdn ting toa nhiit: Phin Ung chiy: C + O^ -> COj - 401,9 kj/mol Phin Ung oxy hda khdng hoan toin; C + / - ^ CO Phan Ung Metan hda: C + 2H,->CH^ Phan Ung luin phien - 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 + , kJ/mol - Kha nang tao ddng hda khong chUa hie in (tar-free) se thugin Ipi cho vi^c cung cap nhien lieu 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 phai cung cap nhi^t cho p h i n flng nen nhiet dp cua ddng hda se giim dan sudt qua trinh khfl PhUPng trinh(4) dupe gpi li phan flng can bang - nfldc (phan Ung luan phien - 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 - nude khdng ddi Trong thUe te, t h i n h phan cin bang cua se chi dat dUpc 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: • M 1 a 1 I| m l-CiiaciipnhiinlifK 2-Vung sdy 3- Viing diilngcit! ~| 4- Ddy Id; 5'Khdng vim 6-Viing kh^ 7-Ghi Id; 8-Gasra; 9- Phin chUa tro: 10- Trau 11-Vimg nhietphtK 12-Viing diHamnH Hinh Buong dot hda 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 di qua viing chay I - Q u i trinh hinh t h i n h dpn gian * Tuy nhien loai budng ddt cd n h # di^m: Sd (Thing nam 2012)- NGHIEN COfU - TRAO D6\ - Kha nang hda 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 ngoii tfl diy eua budng dot hda Budng ddt 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 thieu trao ddi nhiet ben ciing nhU gii tri nhiet cua ddng 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 tri nhiet dp ddng deu cao tren tilt dien chiy- Cd k h i nang hoat ddng vdi nhieu i^^^ nguyen lieu khic (mun cUa, vd ngu cdc ) - Yeu cau ham lupng i m nhien lieu dUa vao h o i phai thap ^^i ^^^ - Khi thoat d efla budng dot hda 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 -^ 7% ham lupng carbon khdng chuyen ddi het - Cie Id phan phdi d l bi oxy hda, v i cd the bi bit kin eac keo nhfla, tar di qua Do vay vdi loai budng dot niy can phai lap dat thiet bi phan phdi 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 thi cic hat nguyen lieu chay chu yeu d phan diy buong dot * , ^ the sfl dung nguyen li?u smh khdi ^^^^^ ^^ ^^ ^^^^^^ ph^n vd cP cao [5] ' Theo [5] gas dflpc tao tfl loai budng ddt 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 khuyen cio Iflu y den vile loai bd hac in neu gas tao dflpe dung viec cap nhien lieu cho ddng ed nd 2.3.3 Budng ddt cd ddng cheo Hinh Buong dot hoa nguyen ly nghich - 15U2] ' Khdng vao budng ddt d phia dfldi va gas t h o i t d phia tren Can d ghi budng dot c i c phan flng chiy xiy v i cic p h i n Ung *niy giam dan theo chieu cao ciia budng dot eac phan tren eua budng ddt hda xiy sfl tddt ndng va nhiet p h i n nguyen lieu v i o nhd Ddi vdi loai niy, thi ddng cap cho qua trinh chay trau budng dot di ngang vdi chieu dich ehuyen cua cdt trau nhiln lieu Tai vung oxy hda loai budng dot n i y cd nhiet dp 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 (Thing nam 2012) NGHIEN CUU - TRAO D O I 3.1 Xic dinh nhiet lU^ng cua buong dot cia cung cip 6i nau in 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 mdi bu6i niu hp gia dinh * Thdng th Udng theo khao sit gia dinh nong H);j/i Budng dot hda c6 ddng cheo [Sj thdn trung binh ed 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 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 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 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 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 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 qua trinh dot trau hoi vi eac nguyen ly Ta di tinh nhiet Ifldng cho tflng lan siJ hoi khi, tic gii Ifla chpn nguyin ly hoa kieu dung budng dot trau hoa de dun nau an nghich de tinh toin thiet ke budng ddt cip nhiet gia dinh moi buoi an sfl dung dun nau cho hp gia dinh ndng thdn theo hfldng nghien cflu TAP CHI CO KHf VIET NAM So (Thing nam 2012)_ NGHIEN ClJfU - TRAO D | 3.1.2.Tinh liidngnUdc uong buoi T = 10/60 - Thdi gian nau nfldc, h (dU kien nau 10 phut) Theo [4]cfl 10kg thi' trpng can 0,4 kg nUde/ G i i sfl trpng Ifldng trung binh mdi ngUdi Idn la 55kg Gia dinh gdm ngUdi Idn vdi tong trpng lUpng la 220kg vi tdng trpng lUpng ngUdi nhd 80kg (lay trung binh mdi ngfldi 40kg) Nhfl vay ta tinh dflpe lUdng nUde can eung ci'p cho gia dinh se l i 12 lit Ta phin bd mdi buoi nau 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 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 =Ii:Jkcalh trUde vi sau nau, "C; T = 15/60- thdi gian nau edm,h; Trong dd: (du kien nau 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 nau, °C ' X = 5/60 - thdi gian lim ndng ndi h; •: (dfl kien l i m ndng ndi nau phut) 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 nau, °C; m^ =6 - khdi Ifldng nfldc can nau, kg T = 10/60- thdi gian nau, h; c = - nhi^t dung rieng cua nfldc, kcal/kg°C (dfl kien nau 10 phflt) At =100 - 28 = 72- Dp chinh leeh nhiet dp :rUdc va sau nau,''C; ^TXS^ui-cri i^of v r e x NAM V Sd (Thing 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 • la doi kinh mat c4t ngang cuaflngtry noi irau bj chiyi hoa 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 riSng, k trudc va sau nau,"Ci m'h Theo [2) ta chpn B= 120kg/m'h Xa chpn dUong kinh buong hoa D: T = 10/60 - thdi gian nau, h; (dU kien nau 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 la toi^ Theo [6] nhiet luong can nau tinh Uj^jng ^^^-i, ,(j ^^„Yt den day buong dothoaUii toan can nhan them he so k t6n that qua (j^'n mat ghi) Chieu cao dUpc xac dinh tion[ trinh nau va each bo tri luc nau khong lien tuc kh^j^g ,hdi gian buong dot hoal dpng 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 nau % TAP CHl CO KHl V I £ T NAM • n L U - 3^ H-chieu cao cua buong dot, m; B= 120- Hf so 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 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 (Thang 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 chay hoa J z = 0,03cm/s 2.5 LUdng khong cdn thiit cho qud trinh od Theo [6], ton that dflpc tinh toin , y ''i /, n ^ IT/- h, = ( , - ^ ( l + p t ) , m m H p ° i V , s^ ,, ,, , LUdng khone cung cap cho buong dot 11 , - « , V , , , ,, , lUdng khong can thiet cho qua trmh / , „ ° ° ^ oa),m^/h: a.ij^^.A _ 0,35.6,1-4,5 _g^3^_Q QQ22it^\^s u n^ 1,2 , :: rong do: a = , - 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 dot trau d tieu kiln binh thfldng ,, ,, , , V , 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 vio buong dot V v^ - van toe dong 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 thiet bl hoa, "C ° Vdi nhiln lieu la trau cd nhiet dp ehiy chiy 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 di qua Idp trau ^ua trinh h o i Q g - ^^^ITi^ "TTTTT^^^ =4,4cm/s ^ 0 ^ ^ - ^ 3600 4 Irong dd: Tra bang dp nhdt ddng hpc cie sach chuyen nginh, d nhiet dp 1050''C, ta tim dflpc dp ^^^^ d5ng hp^ ^fla u = 185,7.10* m=/s • ' 0,058.0,250 , Re=-: ^ =78,1>7 185,7.10' V - Van tdc cua khong xuyen qua Idp nhien lieu,cm/s; Q^ - LUU luong khong cSn thiet cho qua trinh hoa, mVh; < D - Dudng kinh budng ddt, m i; = + | " -555 ' Re Re"' 78,1 78,1""' Vay trd lUc di qua Idp nhien lieu thiet bi hda la: 3.2.7Xac dinh tSn thdt buong dot Vi Re > ( che dp roi) nen ta cd: 048' h = 55,5 ^ ^ i ^ (1 + De cd ca sd thiet ke quat cap cho buong ddt, pham vi tinh toan ta di xac dinh tdn that budng dot TAPjC;v;^f