KHOA HOC - CONG NGHE
NGHIEN CCrU THLTC NGHIEM SAY VAN MONG BANG PHl/ONG PHAP PHUT XA NHIET
TOM TAT
?r^50
Nguyen Dinh Tung '. Nguyin Dinh Quy '. Mai Thanh Huyen ' Bdi bdo ndy trinh bdy kit qud nghien cuu thuc nghiem sdy vdn mong bdng phuang phdp phun xg nhiet. Kit qud thuc nghi'im doi vdi gd keo co dg ddy khdc nhau tie 0,3 den 0.7 mm cho thdy: vdi dg dm trudc khi sdy tie 28% - 65%, tdc dg phut tdc nhdn sdy (tdc do phvl nhiet) 6,2m/s. chi sd bien ton 15-25 Hz. nhiel dg tdc nhdn sdy trong khodng 75-105°C, tuang ung vdi khodng thdi gian sdy tir 2,0-3,38 phiit se dat dugc do dm ciia sdn phdm 5-12%, vdn phdng vd chdt lugng sdn phdm dat lieu chudn xudt khdu.EXPERIMENTAL STUDY OF VENEER DRYING BY THERMAL JET PRESS Nguyen Dinh Tung ', Nguyen Binh Quy ^, Mai Thanh Huyen "*
SUMMARY
This paper presents the result of experimental study of the veneer drying by thermal jet press. The experimental study result of acacia wood with thickness ranging from 03 to 0.7 mm shows that with moisture prior to diying 28% - 65%, thermaljet speed 6.2 m/s, frequency 15-25 Hz, drying agent temperature in the range of75-105°C corresponding to tiie drying time from 2.0 to 3.38 minutes will achieve the product moisture of 5-12%, flat boards and product quality standards for export.
L ©AT VAN DE
Hi?n nay, thj trudng nhilu nudc tren thi gidi nhu Han Quoc, Nhat Bdn vd ngay ca thi trudng Viet Nam cd nhu cau Idn ve tieu thy vdn mdng dung cho nganh san xuat do ndi thdt [3]. Tuy nhien chat lupng vdn mong sau khi gia cong (bdc, lang) neu phai tu nhien se kh6ng dgt yeu cdu chdt lugng, bdi VI phu thupe rdt nhilu vao thdi tilt khi ndng, khi mua, hode khi trdi cd do am cao, dp am thap. Chfnh vi vgy, vi^c say vdn mong bang may say theo phuang phdp phun xg nhiet Id cdn thiet. Ddy la phuang phap, c6ng ngh? mdi d Vi$t Nam cho din thdi diem nay [1]. Vdi phuang phap, cdng nghe sdy nay cho ta chat lupng vdn sau khi say dat tieu chuan xudt khau hoac tieu thu trong nudc.
Ddy la mdt cdng nghe mdi tiet kiem nang lugng, ket cau may nhd gpn, cd the dieu chinh dugc nhiet dp tac nhan say, tdc dp di chuyen ciia van va do day vdn khdc nhau.
n. VAT UEU. PHUONG PHAP NGHIEN CUtJ 1. Vpt lieu nghien cuu
Trong bdi bao nay de cgp den ddi tugng nghien cuu la van mdng tir gd keo lai vdi dp day khac nhau tir 0,3-0,7mm (hinh 1), dp am ban ddu 28-65%, ngupn nhi^t cap tir hai qud nhiet dugc gia nhiet bdi ' Vi?n NghiSn cihi thilt V.k che lao m^y Nong nghi?p (RIAM).
TAP CHf CONG NGHIEP NONG THON - SO? - 2012
ndi hai thong qua bp trao ddi nhi|t calorifer (hinh 2), nhiet dp tdc nhan say duge dieu chinh frong pham vi 75-105 °C [1-3].
Hinh I. Cdc mdu vgi lieu sdy vdn mdng 2. Phuang phdp vd thiet bi nghien cuu Nghien ciiru thyc nghidm dugc tiln hanh ddi vdi gd keo lai cd dp day khdc nhau tij O,3-0,7mm (hinh 1) dugc thuc hien tren may say gd vdn mdng theo phuang phap/cong nghe phun xg nhiet. Mdy say dugc nghien cuu, thiet ke vd che tgo tai Vien nghien ciru thilt kl che tgo may Ndng nghiep- RIAM (Bd Cdng Thuang), may cd kit cdu hai tdng vd dupc kl hieu Jetpress-1380/2 [1-3]. Hinh 2 md td sa nguyen ly hoat dpng, h$ thdng cdp nhiet vd thodt dm cua may sdy van mdng hai tang: Vdn mdng dugc di chuyen bdng he thdng con lan chii dgng phfa dudi va con lan la phdng d phia tren. Tdc nhan sdy (9) tii- kenh phyt nhiet (8) dugc phut tryc tilp vudng gdc len la g6 tir khodng cdeh 50 ^ 60 mm vdi t6c do 6 -^ 8mm/gidy, vi vgy tdc dg thodt am tir Id 7
K H O A H O C - CONG N G H E gd nhanh gdp 4-5 lan so vdi cdng nghe say truyen
thdng bang con Ian thdng thudng vdi tdc nhdn say thdi doc hoac thdi ngang. Trong qud trinh say ddng hai am (11) ben trong budng say dug«: he thong quat ly tam (12) hut ra ngodi [1-3].
' - p ^ — X ^ - 1
" ^ ^ ^ ^ ^ ^ . ^
Hmbl Ngi^enly hogi ddng, he thdng cq!> r^el vd thodt an cua may sdy vdn mong hai tdng iJetpress-138Q^j 1- Ndi h n 2- Gian trao d^ nhiet (Calonfer^ > Khoi^ khi s ^ (fi vk> (di 9ua calorifer); 4- Duci^ ixig din hoi vdng \-k) calorifer 5- Qu^ say. 6- Dui>^ oi^ dv»( luoc r^ur^ 7- Diwigiac l i o i sa)' vk) kenh-^iMiilncr:S-I^A "phut i^ii«r: 9-Tac nhan ^ I0-Rali{4it nhi^ ll-D6r^haamfl)oatra:12-Qudhuthmam
Ma\ sdy Jetpress-1380/2 de thuc hien thi nghiem cd eau tao nhu tren hinh 3. mdy duge che tao va lap ghep vdi nhau theo dang "'block" [1-3].
Thtrc nghiem sdy van mdng gd keo lai dugc hoat ddng, dieu chinh edc thdng sd qua trinh nhd he thdng dieu khien. Ngudn nhiet de cap vao budng sdy nhd hoi qud nhiet dugc Idy tir noi hoi qua dan calorifer hay cdn gpi la bg trao ddi nhiet (TDN), ung vdi mdi mdt bd TDN se gan vdi mpt quat hiit
^ 6 ndng (quat sdy). Hoi nudc qua nhiet dugc Idy tiit ndi hai qua van dieu tiet, sau dd qua cac bg TDN I-^4, gid lanh di qua bp TDN tgo thanh gid ndng sau dd di vdo budng sd\ de Idm khd van nhd cdc quat sd\. Hoi nude ngtmg tu d bd trao ddi nhiet TDNK4 dugc xdqua \an. khdng khf am thodt ratu van mdng dugc quat xa dm hiit ra khdi budng sdy (xem hinh 2). Ndng sudt say ciia timg loai van cd dp day khac nhau da duge djnh san theo edng n ^ e . Toe dp djch chu\en eiia timg toai van (iiiy theo dp day mdng khac nhau cua vat lieu say) se dugc dilu chinh bdng bien tdn mgt each de ddng [1-3]. Duy nhdt ed nhi^t dp tdc nhan sa\ Id bj thay ddi lien tuc trong qud trinh lam kho van mdng \i trong buong
say \ an mdng thu nhiet de thai am, quat xa khi am ra ngoai va dp sudt h<n nuoc cap tir ndi hai cd khi ciing bi ha thap nen nhiet dp hoi nudc bao hda (gpi tdt Id hai nudc) cap vao bd TDN trong buong sly cting thdp di. Vay de on djnh nhi^ dp budng say [rfiai lien tuc bu them luu lugng hoi nirdc khi ma nhiet dp budng sdy ha xudng bdng c ^ h lip them a phdn dau vao c ^ hcri nuoc mot nhanh phu vd dtrgc dieu khien bdng van dien tir. Van dien tir se dugc dieu khien tir dpng ddng mdr de bu nhiet nhd bd cam bien nhiet dp. Khi nhiet dp trong budng say dat din nhiet dp cdi ddt thi van dien tir se tu ddng ddng lai khdng edp hoi nudc cho bd TDN nira. Trong qua trinh say khi nhiet dp trong budng sdy gidm dii dau cam bien nhiet dp se dua tin hiai dieu khien van dien tir thdng qua cap tiep diem etia bd dieu khien nhiet do de cap them hoi nudc vao bd TDN. Nhiet dp cai dgt d bd dieu khien nhiet de Idm khd van mdng phu thude vao dp dAy cua timg logi van vd tiiy theo yeu cau cdng n ^ e [1-3].
Hinh3. Mdysdyvdnma^J^3ress-1380.2 III. KET QUA V.\ THAO LUAN Ket qua n ^ i e n cihi chiu dnh hudng bdi cdc thdng sd thi nghiem (thdng sd ddu vdo, dau ra). Cac thdng s6 thi nghiem d ddy; dp dm van (vat lieu), dp ddy vdn, tde do sdy th6ng qua chi sd bien tan, ndng suat say. Ngoai ra, ket qua n ^ i ^ cuu cdn chju dnh hudng bdi phuang phap, nhdt la thiet bj do phye vu n ^ i e n ciru.
Cdc thiet bj do dugc sir dung trong n^ien ciru la eae thiet bj do cdm tay: ddng h6 do Itni lupng, van toe va nhiet dp tac nhan say: do lini lugng, dp sudt eua quat; thilt bi do dp dm loai cd djnh \a logi do nhanh cam tay d l do do am eiia vat lieu trudc va sau khi say. Htnh 4 sau day md td cae thiet bj do khi nghien ciru. Ngoai ra cdn eo cac ddng ho do hien thj s6 tren tu dien dilu khien, cdc sensor edm bien nhi?t do, ^ an dieu chinh tu dgng hm nuoc... [2,3].
8 TAP CHi CONG NGHIEP NONG THON - SO 7 - 2012
KHOA HQC - CONG NGHE
Hinh 4. Cdc thB bi do dugc sud^ig trang thuc n^iim a.b - Do viin t6c phyt gid, do liru lirpng, do c$t ap cua qugt;
c - Do nhiet dp. d- Mlu do do km, e,f - Do dO im cl dinh va do dg am c^m tay (do nhanh).
Sa d6 bl Iri vj tri do lay mau dp dm ciia vat lieu trudc vd sau khi say dugc trinh bay tren hinh 5.
a e
©
©
©
Hmh5 Vitriddxdc^nhdgdmcikivgtliiusdyngciylrenldm vdn tmdc vd sau Idii .vqv hdng thiet bido do dm nlwih cdm lay
Kit qua nghien ciru thyc nghiem ddi vdi mgt s6 Ipgi g6 mua tgi cac xudng gia cong gd bdc d Yen Vien - Ha Npi, gd lang d khu cdng ngliiep Quang Minh - Ha Ndi, vdn cd chilu day tir 0,3mm den 0,7mm. Cdc mdi quan he giira cdc thdng s6 ciia qud trinh nhu dp am san phdm (dp dm van sau khi sdy) vdi nhi?t dg tdc nhan say, tdc dp di chuyen van, van toe phyt nhi?t (vgn toe tac nhan sdy) va thdi gian say dugc thi hi^n tren cac do thi 1 -3 hinh 6.
Theo cac tdi lieu [4-6] nhi?t dp tdc nhdn say eho mpt s6 loai vdn mdng dao dpng trong khoang 80-140**C, lay dd Idm ca sd de lua chpn nhiet dp cho qua trinh thirc nghiem tu' 75-105°C.
Hinh 6. Do thj moi quan he giua cdc Tren do thi 1 cho thdy ket qua thi nghiem the hien cdc mdi quan he giira cdc thdng s6 dp dm van mdng, nhiet dp tdc nhan sdy, chi sd biln tdn (d ddy la van tdc dieh chuyen vdn trong may say) thay ddi keo theo thdi gian say thay doi, tir dd nang suat say thay ddi theo. Tren hinh 1 chi sd bien tdn dugc thuc hien thay ddi (dieu chinh) d hai viing gid trj ldm viec (xet tir phai sang trdi tren do thi): viing I (12- 15Hz) vd viing 11 (20-25Hz), thdi gian say d hai viing nay khdng thay ddi nhieu (do thj 1), nam trong khoang 2,0-2,32 phiit. Tuy nhien d viing I khi chi sd biln tdn thdp (van tdc di chuyen vdn chdm) thi nhiet dp tdc nhdn sdy viing ndy phai cao han so vdi vung II (nhiet dp sdy viing 1 80-86 °C), d viing II chi so biln tan cao han (van tdc di chuyen vdn nhanh), nhiet dp tac nhan sdy viing nay thdp han viing I (nhiet dp sdy viing 11 70-83 °C). Nhu vdy da phii hgp vdi quy lugt.
Tren dd thj 2 cho thdy: chi sd biln tdn thay d6i tir 15-21 Hz, dilu dd cd nghia van tdc di chuyen eiia van trong mdy sly thay doi. Trong khi do de giU cho nang suat sdy 6n djnh, dp am san phdm dn djnh (dd thi 2) theo yeu cdu cdng nghe, liic nay thdng sd nhiet dp tdc nhdn say thay doi (tang hoac giam) tiiy theo su thay ddi ciia chi sd biln tan. Qua dd thi 2 cho ta thay quy luat thay ddi ciia mli quan he nhi?t dp tac nhdn sdy theo chi sd biln tan rdt diing quy lugt.
Qua do thj hinh 3 thi hi§n cdc m6i quan hp giiJa chi sd bien tdn, dp am van va nhiet dp tac nhan sdy cho thdy, sy thay ddi ciia chi sd bien tdn (sir thay ddi ciia van tdc di chuyin vdn trong may say) vd su thay ddi ciia nhi?t dp tdc nhan sdy theo dung quy luat, tuy nhien khi so sdnh giiia hai vung cho thdy. CJ viing I su thay ddi chi s6 biln tdn tir 8Hz din 12Hz theo bien dg nhd hem so vdi virng II tir 15-22Hz, khi do nhiet dp tac nhan sdy d viing I ndy cung thay doi vdi bien dp nhd ban so vdi viing II trong khodng thdi gian say duy tri tir 2,29-3,05 phut.
TAP CH[ CONG NGHIEP NONG THON - SO 7 - 2012 9
KHOA H O C - C O N G N G H E Nhan xet: Tir edc dd thi tren cho thdy: mdi
quan he giira cdc thdng s6 nhu da neu tren rdt dung quy lugt, diing cdc quan he tuang quan cd ve quy ludt va gid trj. Qua ket qud ndy cho thdy mdy say hoat ddng dn dinh ca hai tdng tren vd tdng dudi, dieu dd cho thdy phan khi ddng hpe da dugc tinh todn. thiet ke hgp ly. Ngodi ra nhiet dp tdc nhan sdy, l6c dp di chuyen van (dieu chinh t6c do bang bien tdn), tdc dp phut ciia ddng tac nhdn sdy trong kenh phyt nhiet vd thdi gian sdy duge lua chpn thi nghiem Id hgp ly, dgt yeu cau ky thugt.
Vdi cdc thdng sd nhiet dp tde nhdn say 75 - 85°C, toe dp phyt nhi?t (tdc dp tac nhan say) giir d muc 6,2m/s, cho thdy cdc mau gd van lang, vdn bdc, sau khi say Idn I dat dp am 5,2-5,4%. duoi mire can thiet (trong khi yeu cau 8-10%) vdi thdi gian say rdt ngdn khodng 2,0-2,2 phiit, nhu vdy sau mgt lan say Id dat yeu edu; chdt lugng be mat vdn lang rdt phdng, khdng hi rach, khdng cong \enh. hodn toan dap umg yeu cdu ciia khdch hdng.
Vdi cac th&ig s6 nhiet dp tdc nhdn say 90 - 105°C, tde dp phut nhiet (tde dp tac nhdn sdy) giir d mure 6,2m/s, cho thay cac mdu gd keo d6i vdi vdn bdc tir dp dm 38-65% sdy khd xudng dp am 8-12%, vdi thdi gian sdy 2,2-3,38 phiit. Ngoai ra chat lugng bl mat sdn phdm van hoc rdt phdng, khdng bj rdch, khdng cong venh, hoan toan ddp ling )eu cau eua khach hdng vd xudt khdu (dp am yeu edu vdn xuat khdu sang thj tnrdng Han Quoc tir 14-16%). Tuy nhien, d cdc dd thj tren cd cdc virng s6 lieu loai bd, ly do cdc s6 lieu dd bdt hpp ly Id do dp am dau vdo ciia cdc mdu dao ddng rdt Idn.
IV. KET LUAN
Nhu vgy, vdi mdy sdy cd ket edu hai tang neu tren ed tdng cdng sudt dien ciia thiet bj la 24,5 kW.
Ndng lupng dien tieu tiiu trong mpt ea 8h Id 196kWh.
Mdi ca trung binh say dugc 5.800m^ vdn mdng, nhu vdy Im^ vdn mdng say tieu tdn 0,033kWh. Sp sdnh vdi cdc logi hinh cdng nghe sdy khac cho thdy phucmg dn cdng nghe sdy phun xg nhiet tieu tdn it nang lugng dien nhdt.
Mdy sdy vdn mdng theo phucmg phdp phun xa nhi?t cd diem khdc biet ciia cdng nghe ndy la trong qud trinh sdy vdn mdng dupc Id phdng bdng he thdng con Idn ndng phia tren va phia dudi, ddc biet ddy con Idn tren cd tac dung miet vd Id phdng van mdng trong qua trinh di chuyen ben trong may.
Dieu nay cd tac dyng rdt Idn den dp phang mjn ciia vdn mdng sau khi sdy ma cac loai hinh cdng ngh?
khdc khdng the cd dugc.
Chat lugng eua sdn phdm sdy dugc phan anh qua cac chi so ky thudt cu the nhu sau:
- Ddi vdi van lang cd dp day 0,3mm, vdi dp dm ddu vdo W, = 28-30%; dp dm ddu ra W, = 5,2-5,4%.
vdi nhiet dp tdc nhdn say 72-80°C, toe dp cita ddng tac nhdn sdy d mieng kenh phut nhiet 6,2m/s, khi do thai gian sdy 2,0-2,2 phut.
- Ddt vdi van Igng cd dp day 0,4mm, vdi dp am ddu vdo W| = 29-30%; dp dm ddu ra Wi = 8-10%, vdi nhiet dp tdc nhdn say 80-100°C, t6e dp ciia ddng tdc nhan sdy d mieng kenh phyt nhiet 6,2m/s, khi do thdi gian sdy 1,4-3,0 phut.
- Ddi vdi van bdc cd do day 0,7mm, vcri dg dm dau vdo W, = 28-65%; dp dm ddu ra Wj - 7.5-8,5%, vdi nhiet dp tac nhan say 80-105°C, tdc dp cua ddng tdc nhan say d mieng kenh [^ut nhiet 6,2m/s, khi dd thdi gian sdy 2,05-3,33 phiit, vd nhiet thdi dm 6I-72X.
Qua ket qud thuc n ^ i e m eho thdy: chdt lugng be mat vdn bdc rdt phdng, khdng bj rdch, khong bj cong venh, hodn toan ddp ting yeu cdu xudt khdu.
Tuy nhien tir s6 li?u phdn tfch tren ddy cdn cho thay mpt dieu rdng: ddi vdi vdn lang (dg ddy 0,3-0,4mm) do dm sau khi sdy la rdt ddng deu va cd gia trj thap ban so vdi dg dm yeu cdu. Do dd can phai sdy vdi tdc dp nhanh han niia, hode ddt nhiet dp tdc nhan sdy thdp ban 5-10°C so vdi nhiet dp neu tren detilt kiem chi phf nang lugng sdy.
TAI LI$U THAM KHAO
[1]. Nguyen Dinh Tiing, Dang Huu Tikp. Nguy&i Dinh Qu)' (2012). M9I so kh qua nghien oju. thidt kl chl t ^ thilt bj sky \ia\
mong bang cong n ^ e "phun nhi^ & la f^ang". T^p chi Cong nghidp Nong thdn, Hpi co khi Nong nghiep Vi?l Nam. s6 6/2012
[2]. NguyIn Dinh Tiing (2012). Nghien cmi. thiat kl v4 chl t^o may s3y van mong theo phirong phap phun \a nhi?L T ^ chl co khi Vict Nam. s6 7/2012.
[3]. NguyIn Dinh Tung va cs (2009). Bao cto n g h i ^ thu h$i ddng CO so de tai "nghien cuu tfiiet ke chl t^o may s ^ van mong theo phaang phap phun xa nhiet, nang ai5t 3-34m3/ca Dl t^ c ^ BQ. Bp NN&PTNT, 5/2012.
[4]. Krischer. K. (19S6). Trodmungsteduulc Band I: Die wissensdiaft-lichen Grundlagen der Troduiungstechnik, Springer- Veriag Berlin, 1956.
[51. Krischer. K. (1956). Trocknungstechnik. Band 2:
Trockner und Trocknu^gs^'erfehren. Springcr-Verlag Berlin. 1959.
[6]. Janik, W. (1965). Handbuch der Holzlnicknung. 2..
vert)esserte Auflage, Fachbuchvcrlag 1-crpzig 1%5.
Nguoi phan bieu: TS. Nguyen Van Doan
10 TAP CHI CONG NGHIEP NONG THON - SO 7 - 2012
