14*KH&CNN 91*01/2010 TIEM NANG TO L O N VE TIET KIEM NANG LlTONG KHI SLT DUNG HOI Nl/OC TRONG CONG NGHIEP I DATVANDE Hdi nudc dUdc sii dung phd bien nham cung cip nhiet nang cho cac qua tnnh cdng nghe[.]
14*KH&CNN - 91*01/2010 TIEM NANG TO L O N VE TIET KIEM NANG LlTONG KHI SLT DUNG HOI Nl/OC TRONG CONG NGHIEP PGS TS TRaONG DUY NGHIA I.DATVANDE Hdi nudc dUdc sii dung phd bien nham cung cip nhiet nang cho cac qua tnnh cdng nghe cua san xuat cdng nghiep Viet Nam, theo thdng ke, tdng cdng suit hoi cdng nghiep hien khoang 6000 tan/gid, tieu thu khoang trieu tin than quy ddi mdi nam Tuy nhien hieu suit sii dung nang lUdng d ca khau san xuat hdi nudc va khau sCf dung hdi nUdc nhin chung cdn thap: - d khau san xuat hdi (tai Id hoi), hieu suit nhiet cua Id hdi thudng khdng qua 70% - d khau phan phdi va sif dung hdi, theo cdng nghe va dac diem hien dai cua thiet bi sCf dung hdi, hieu suit SLf dung nhiet cua hoi nudc dao ddng tCr 20 -90% Qua khao sat thUc te, chiing tdi thiy rang neu ap dung cac bien phap nang cao hieu suit san xuit va sir dung hdi nUdc cdng nghiep thi it nhat cd the giam dugc nhien lieu tieu thu tff 10 - 15% Cac bien phap nang cao hieu suit san xuit va sCf dung hdi nUdc deu la cac bien phap khdng ddi hdi ky thuat phUc tap, tai nha may cdng nghiep nao cung cd the ap dung dUdc Bai viet de xuit mdt sd bien phap cu the de cd he ap dung thuc te sin xuit cua xi nghiep II DAC DIEM SL/ DUNG HOI NUCiC TRONG CONG NGHIEP 2.1 Tinh chart cua hoi nudc bao hoa Hdi nudc dung cdng nghiep chu yeu la hdi nudc bao hoa am Rit hiem cd xf nghiep sii dung hdi bao hoa khd hay hdi qua nhiet NhU da biet, entalpi cua hdi bao hoa am tai ap suit p dUdc xac dinh theo cdng thCfc: hbh=h' + rx,kJ/kg (1) Trong dd h' - entapli cua nudc bao hoa (nudc sdi), kJ/kg, r - nhiet hoa hdi d ap suit p, kJ/kg, x - khd cua hdi Hau het cac Id hdi cdng nghiep deu cd the tich chCfa hdi be (khoang hdi), chieu cao cua khdng gian hdi rit thip, thudng chi bang 0,2 - 0,3 m, thip hon nhieu so vdi chieu cao cin thiet de ddng nang cua ddng hoi nudc khdi khoang hdi khdng du sCfc mang theo cac gigt nudc am Trong khoang hdi cua cac Id hoi cdng nghiep cung gin nhU khdng bd tri cac thidt bi phan ly hdi khdi cac giot nUdc am Hon nCfa thuc te van hanh, viec cip nUdc cho Id hdi la dinh ky, khdng lien tuc theo lugng hdi sCf dung MUc nudc ket thCic cip nUdc thudng d mCfc cao nhit (lam cho chieu cao cua khdng gian hdi cang bi giam di) Khi hdi nudc da khdng la hdi nUde bao hoa khd thi entalpi cua hdi bi giam di rat nhieu, du ap suit cua hdi khdng thay ddi Trong bang gidi thieu sU giam entalpi cua hdi nUde giam khd cua hdi Mat khac, tdn thit toa nhiet xung quanh dan hdi tU Id hdi den thiet bi sCf dung hdi (mang nhiet) cung lam tang am cua hdi Bang Cac dac tinh nhiet cua hai a cac kho cua hai Entalpi hdi bao hoa kho, kJ/kg x = 0,6 x = 0,8 x = 0,9 x = 0,7 Ap suat, MPa Nhiet bao hoa, °C Entalpi nu6c bao hoa, kJ/kg 0,1 99,6 417,5 2,257,9 2.675,4 0,2 120,2 504,7 2.201,6 2.706,3 0,3 133,5 561,4 2.163,2 2.724,7 0,4 143,6 604,1 2.133,0 2.737,6 0,5 151,8 640,1 2.107,4 2.747,5 0,6 159,9 670,4 2.085,0 2.755,5 Nhiet hoa hdi, kJ/kg x = 1,0 2.449,6 91,56% 2.486,1 91,86% 2.508,3 92,06% 2.524,4 92,21% 2,536,8 92,33% 2.546,9 92,43% 2.223,8 83,12% 2.266,0 83,73% 2.291,9 84,12% 2.311,1 84,42% 2,326,0 84,66% 2.338,4 84,86% 1.998,0 74,68% 2.045,8 75,59% 2.075,6 76,18% 2.097,8 76,63% 2.115,3 76,99% 2.129,9 77,30% 1.772,2 66,24% 1.825,7 67,46% 1,859,3 68,24% 1.884,5 68,84% 1.904,5 69,32% 1.921,4 69,73% KH&CNN - 91*01/2010*15 Bang Ton that nhiet theo cac ty le ngung hai Ton that nhiet theo cac ty le ngUng hdi Nhiet hoa hdi, kJ/kg Ap suat, MPa Ty le ngung 0,9 Tuyet doi, kJ/kg % Ty le ngung 0,7 Ty le ngung 0,8 Tuyet doi, Tuyet doi, % % kJ/kg kJ/kg Ty le ngung 0,6 Tuyet doi, kJ/kg % 0,1 2.257,9 225,8 8,4 451,6 16,88 677,4 25,3 903,2 33,8 0,2 2.201,6 220,2 8,1 440,3 16,27 660,5 24,4 880,6 31,9 0,3 2.163,2 216,3 7,9 432,6 15,90 649,0 23,8 865,3 31,8 0,4 2.133,0 213,3 7,8 426,6 15,60 639,9 23,4 853,2 31,2 0,5 2.107,4 210,7 7,7 421,5 15,30 633,2 23,0 843,0 30,7 0,6 2.085,0 208,5 7,6 417,0 15,10 625,5 22,7 834,0 30,3 Ghi chu: T^ le ton that nhiet dupc tinh so vdi entalpi cCia hai bao hoa kho Bang Luang nhiet thu hdi tdnudc ngung Ap suait, MPa Entalpi nudc bao hoa, kJ/kg LUdng nhiet thu hoi tit nudc ngung giam nhiet nUdc ngUng 40°C 60°C 20''C 70''C kJ/kg kJ/kg kJ/kg kJ/kg % % % % 83,7 167,4 251,0 60,1 40,1 20,0 292,9 70,2 0,1 417,5 0,2 504,7 83,7 16,6 167,4 33,2 251,0 49,7 292,9 58,0 0,3 561,4 83,7 14,0 167,4 29,8 251,0 44,7 292,9 52,2 0,4 604,7 83,7 13,8 167,4 27,7 251,0 41,5 292,9 48,4 0,5 640,1 83,7 13,1 167,4 26,2 251,0 39,2 292,9 45,8 0,6 670,4 83,7 12,5 167,4 25,6 251,0 37,4 292,9 43,7 Ghi chu: Nhiet dung rieng cCia nudc ngung lay gan bang 4,184kJ/kg°C a cac nhiet va ap sua't khac nudc ngung Ty le nhiet thu hdi dUCc tinh so vdi entalpi cCia nUdc bao hoa 2.2 Dac diem cua thiet bj sur dung hoi nudc Da sd cac thie't bj sCf dung hdi nUde cdng nghiep la cac thie't bj trao ddi nhiet gian tiep, ay hdi nudc nha phin nhiet cua minh cho chit dugc gia nhiet chu yeu bdi nhiet hoa hdi r Neu hdi nude nha het phin nhiet hoa hdi cua minh thi toan bd hdi nudc ngung tu nudc Trong rit nhieu thiet bj trao ddi nhiet, hdi nude rat khd nha het toan bd lugng nhiet hoa hoi cua minh Phan nhiet hoa hoi khdng nha het gay nen tdn thit nhiet Tuy theo thidt bj trao ddi nhiet, theo hieu qua lam viec cua van tach nudc ngung (van bay hdi, van cdc, ), tdn thit cd the rat Idn, tham chi tdi 80 - 90% net khdng cd van tach nude ngung Ta cd the thay rd dieu d bang ve tdn that nhiet theo cac ty le ngung hoi Tuy theo ap suit cua hoi dUa tdi, nhiet nUdc ngung la nhiet bao hoa (nudc sdi) tai ap suat hoi thudng cao hon nhiet sdi tai ap suit quyen (lOO'-'C), neu khdng dugc tiep tuc tan thu nhiet thi cung gay nen tdn thit nhiet (xem bang 3) III TIEM NANG TIET KIEM NANG Ll/ONG KHI SLT DUNG HOI Nl/CJC 3.1 Tai khau san xuat hdi Giai phap chu ye'u la - Nang cao hieu suit nhiet cua Id hdi; - San xuit hdi bao hoa khd hoac qua nhiet hdi vdi qua nhiet be 3.1.1 Nang cao hieu suat nhiet cua Id hdi Cac tdn thit nhiet Idn nhit ddi vdi cac Id hdi cdng nghiep la: - Tdn thit chay khdng het nhien lieu, quen ggi dd la tdn thit chay khdng het ve cd hgc q4 (Unburn loss) Hien than dung cho cac id hdi cdng nghiep thudng la than cue, cd hat Idn (tCf 1-2cm tdi tren 10cm), dieu kien tiep xuc giCra than va khdng khd 16*KH&CNN - 91*01/2010 xay hoan toan nen Idi cue xi cdn lan nhieu than chua chay Qua thi nghiem thUc td, tdn thit ttiUdng tren 10%, d nhieu Id hdi ky thuat dot kem, tdn thit tdi tren 20% nhCrng Id hdi ddt dau FQ, cac vdi dot phun sudng kem, cham id, tdn that chay khdng het nhien lieu cung thudng Idn (the hien d khdi den dng khdi) - Ton that theo khdi thai, d da sd cac Id hdi cdng nghiep, nhiet dp khdi thai thudng rat cao, phd bien khoang 36o°C, chi mdt sd it Id hdi cd nhiet khdi thai khoang 200°C hoac thip hdn Do nhiet khdi thai cao nen tdn thit kha Idn, thudng tCf 15-20% - nhCrng Id ddt than cam, phai trdn nUdc vao than de than dd bj bay chay quay gid cOng gay nen tdn thit nhiet de bdc hdi lugng nudc Nhin chung hai tdn thit nhien lieu chay khdng het va khdi thai la hai ton that Idn nhit san xuat hdi cua Id hdi, cung vdi cac tdn thit nhiet khac lam cho hieu suit cua cac Id hdi cdng nhiep chi vao khoang 60 - 70% Viec giam tdn thit nhiet nhien lieu chay khdng het chu ye'u phu thudc vao trinh tay nghe cCia ngudi thg ddt Id Xi nghiep can thie't phai xac djnh lUdng cacbon cdn lai xi de ngudi thd dot Id thiy rd hieu qua cua viec dot than Rieng ddi vdi nhCfng Id hdi dd diu FO, cd the xac djnh tong ton that tCf thi nghiem can bang thuan Id hdi De giam tdn thit khdi thai, cin giam nhiet khdi thai Do nhiet dp khdi thai cua cac Id cdng nghiep kha cao nen cd the dat bp ham nUdc de tan dung nhiet thCfa cua khdi thai Cung cd the dat bd qua nhiet de qua nhiet hoi nham tang entalpi cua hdi hoac bd siy khdng de dot ndng khdng khf cung cip cho qua trinh chay Trong cac bien phap tren, bien phap dat them bd ham nudc la ddn gian nhat, i y cin bao dam nhiet dng bd ham nudc khdng nhd hon nhiet dp dpng suong cua khdi 3.1.2 San xuat hoi bao hoa khd hoac hdi qua nhiet Theo bang 1, hdi bao hoa khd lam tang entalpi CLia hdi va dd lam tang hieu qua trao ddi nhiet lai thiet bj sir dung hdi, tao dieu kien lam giam tdn thit khdng ngung het hdi nudc 3.2.Tai khau phan phdi hoi Tai cac xi nghiep mdi xay duTig, cac mang nhiet la mang hoan chinh ca ve mat thuy lUc cung nhu ve nhiet, i y tdn that nhiet thudng khdng qua 5% Tuy nhien tai rit nhieu xi nghiep, qua trinh phat trien, mang nhiet thudng dUdc phat then khdng tuan thu cac quy tac ve thuy lUc, each nhiet chap va, rd ri hdi nudc nhieu nen tdn that nhiet qua mang kha Idn, cd the tdi tren 10% cua tdng lUdng nhiet sCf dung De danh gia mUc dp tdn thit nhiet qua mang nhiet cd the dung phUdng phap xac djnh dp giam entalpi cCia hdi nUdc tU khau san xuat hdi d Id hdi qua mang nhiet, tdi thiet bj sCf dung hdi Hdi KHKT Nhiet Viet Nam da tao thiet bj entalpi cua hdi nudc tai cac diem cin va cd the dugc sif dung de xac djnh tdn thit nhiet qua mang nhiet Bang Dung van tach nudc ngung cua Cong ty Det Kim Dong Xuan (van lap theo thiet bi toan bo) TT Dai lUdng Ky hieu Lan doi Lan Lan Lan Lan Lan 0,8 0,8 0,8 0,8 0,8 ,08 Vngu 201,7 201,7 202,3 202,3 202,3 202,3 Nhiet ban dau nUdc lam nguoi, °C ^ngul 26,2 29,8 29,5 30,9 32,6 34,4 Nhiet cudi cua nUdc lam nguoi, °C ^tngu2 29,9 31,5 30,9 32,6 34,4 36,3 The tfch nudc ngung, ^ngg 27,0 11,9 10,56 18,93 19,36 23,41 Nhiet nudc ngUng, °C ngg 79,2 80,9 82,4 89,8 88,4 90,2 Hieu qua, % 11 91,48 89,09 91,39 90,00 92,82 92,64 Ap suat hoi, bar The tfch nudc lam nguoi, P KH&CNN - 91*01/2010*17 Bang (4 tiep) Khi dung van tach nudc ngung mua le, lap thay TT Dai iLTdng Lan Lan Lan P 0,8 0,8 0,8 202, 202, Ky hieu Bang (4 tiep) Khi khdng dung van tach nudc ngung Dal lucfng Ky hieu Ap suat h(3i, bar The tich nudc lam nguoi, y.g 202,6 Nhiet ban dau nu'dc lam nguoi, °C ^ngul 28,9 31,1 33,4 Nhiet cuoi cua nudc lam nguoi, °C 31,1 33,4 36,6 Nhiet cuoi cua nu'dc lam nguoi At,•ngu2 The tich nudc ngung, ,vng g 9,6 10,1 16,4 The tich ngung ni/dc Angg Nhiet tngg 75,3 77,2 76,5 Nhiet dp ngung, °C nuflc 11 67.0 61,8 63,1 nudc ngung, °C Hieu aua, % 3.3 Tai khau sudung hdi Tdn thit nhiet chu yeu tai day khdng sif dung het nhiet hoa hdi cua hdi nUdc De khac phuc tdn thit tai da sd cac thiet bj sCr dung hdi deu cd lap van xa nudc ngung (bay hdi) Tuy nhien tren thi trudng hien cd rit nhieu loai van x i nudc ngung cd hieu qua lam viec rit khac nhau, dd nhieu loai, sau mdt thdi gian SLT dung da giam tac dung biy hdi di rit nhieu Nudc ngUng cung vdi hdi xa thudng dUde dau chung vao he thdng dng nude ngung, la he thdng kfn nen ngudi sCf dung thudng rat khd danh gia hieu qua van biy hdi Chung tdi da lam thf nghiem danh gia hieu qua cua mot sd loai van biy hdi, thiy rang hieu qua biy hdi cua cac loai van chenh rit nhieu (xem bang 4) H 1.1 Co cau tach nirdc ngimg ki«u phao Hien da xuit hien loai van bang hdi kieu tiit luu , tac ddng tu dgng vdi Id tiet luu (Id xa) rit be, hdi xa cd td'c Idn, trd luc chuyen ddng Idn nen khdng di qua dugc lo tjet iuu Qua kinh nghiem sCr dung nhieu nam, van biy hdi kieutiet luu td cd uu diem ndi trdi so vdi cac loai van biy hoi khac Sd dd nguyen ly mdt sd loai van biy hdi dugc chi tren hinh 1.1,1.2,1.3,1.4 Dcin vl Ket qua thi nghiem The tich nifdc lam nguoi 203,0 Nhiet ban (Jau nudc lam nguoi 29,1 33,6 I 18,5 77,4 16,6 % Nhu vay neu khdng dat van biy hdi thi hieu qua SLT dung hdi chi dat khdng qua 20%, dung van biy hdi chat lugng khdng cao hoac khdng dUdc bao dudng thudng xuyen thi tdn thit nhiet cd the tdi 40 50% Trong thuc te, tai nhieu xf nghiep sau dat xong van bay hdi, hau nhu khdng cd che bao dudng djnh ky nen tdn thit nhiet thudng Idn va la tdn thit nhiet khdng nhin thiy IV KIEN NGHj Tren co sd trinh bay tren, chung tdi cd mdt sd kien nghj sau: 4.1 Can thiet phai che tao nhumg 16 hoi dat cac chi tieu cao ve hieu suat, ve thai bui va khdi thai de lam mau trinh dien va lam co sd de danh gia cac 16 hoi khac De thuc hien viec nay, cin xay dUng phUdng phap tieu chuan xac djnh hieu suit Id hdi, tU dd de djnh mUc tieu chuan ve suit tieu thu nhien lieu de sin xuat 1kg hoi nudc Tren cd sd phUdng phap xac dinh hieu suit Id hdi, cac xf nghiep ca nUde tidn hanh hieu xuat Id hdi cua xi nghiep minh, dd'i chieu vdi cac djnh mCfc tieu chuan de danh gia hieu qua san xuit hdi cua xi nghiep minh Vi Id hdi cd nhieu chung loai khac nhau, cdng suit ap suit va nhien lieu sir dung khac nen phUdng phap tieu chuin xac djnh hieu suit Id hoi va djnh mCrc tieu thu nhien lieu de san xuit hdi cung cin xet den cac yeu td 4.2 Tien hanh xac djnh ton that nhiet cac mang nhiet cua cac xl nghiep cong nghiep bang each entalpi cua hoi d dau va cudi mang nhiet Co the tien hanh entalpi cua tung nhanh mang nhiet rieng Nhu vay cin thiet phai cd thiet bj entalpi cua hdi nude Hoi KHKT Nhiet da che tao cdng thie't bj entalpi cua hdi nUde dat sai sd cho phep ky thuat Hieu qua 18*KH&CNN - 91*01/2010 y//'/////////zz VAN TACH VAN CHAN —1>- NGt/NG VAN CHAN -HX3- —CXhVAN CHAN Hinh 1.2 cd cau phao kieu mang Hinh 1.3 dirdng di tat qua cd cau tach nudc ngimg i ¥v>A\f^ thoSt luri nu