Bai a. Viet_So 12

THNG TIN KHCN S& HOT NGs

TP CH KHOA HC V CNG NGH THY LI S 12/2012 41

CNG NGH KH HA S DNG PH PHM NNG, LM NGHIP PHT IN CNG SUT NH

ThS. Nguyn Minh Vit, ThS. Anh Tun Vin Thy in v nng lng ti to

Tm tt: Ngun nng lng sinh khi (biomass) t ph phm nng, lm nghip Vit Nam rt ln, vic tm hiu cc cng ngh v thit b khai thc ngun nng lng ti to ny l rt cn thit, nht l trong bi cnh thiu ht nng lng ngy cng tr nn trm trng nc ta. S dng Biomass va nhm gim vic s dng ngun nng lng truyn thng nh thu in, du m v than va lm gim pht thi kh nh knh, gim nhim mi trng. Bi bo ny nhm gii thiu cng ngh kh ho (Gasification) khai thc ngun nng lng biomass t ph phm nng, lm nghip pht in quy m nh cho cc h, nhm h gia nh, cc c s xay xt.

Summary: Biomass energy sources from agricultural by-products, forestry in Vietnam is huge, searching the technology and equipment to use renewable energy sources is essential, especially in the absence ofthe energy gap is more and more serious in Vietnam, and to reduce the use of energy sources such as hydropower, oil and coal, just as greenhouse gas emissions, reduce environmental pollution. This paper to introduce gasification technology biomass energy exploitation from agricultural products, small-scale forestry to generate electricity for households, household group, milling facilities.

I. T VN Nng lng ng vai tr rt quan trng trong s pht trin kinh t. Nn kinh t cng pht trin th nhu cu v nng lng cng ln dn n suy gim nhanh chng ngun nhin liu ha thch, y gi nhin liu (xng du, than, kh) ln cao v gia tng lng kh CO2 thi vo kh quyn, gy nn hiu ng nh knh, bin i kh hu ton cu. Do , ngoi nhng nghin cu gii php s dng nng lng tit kim v hiu qu th nghin cu, ng dng nhng cng ngh mi nhm pht trin, to ra ngun nng lng thay th, b sung cho cc ngun nng lng ho thch cn c quan tm. Ngun nng lng biomass t ph phm nng, lm nghip (rm, tru, phoi bo, g, x da, v c ph, b ma, thn v li ng, lc) l mt trong nhng ngun nng lng mi, nng lng ti to cn c quan tm nghin cu khai thc. Trn th gii, cng ngh gasification (cng ngh kh ho) s dng ph phm nng, lm nghip to ra gas cho un nu, h thng l si, chy my pht in, chit sut thnh nhin liu kh ho

lng... c ng dng rt nhiu. Vit Nam, cng ngh ny cng c mt s c s nghin cu v ng dng ch to cc bp kh ho un nu cho h gia nh hoc to nhit cho h thng sy nng sn. Tuy nhin, cha c nhiu nghin cu ng dng cng ngh gasification s dng ph phm nng, lm nghip pht in, trong khi ngun nguyn liu ny nc ta rt ln. Bi bo ny gii thiu v cng ngh gasification s dng ph phm nng, lm nghip pht in cng sut nh cho cc h hoc nhm gia nh, c s ch bin nng, lm sn, c s xay xt ph hp vi iu kin kinh t x hi Vit Nam. II. NNG LNG BIOMASS L G? Biomass l mt ngun nng lng lu tr nng lng mt tri di dng cc cht ho hc thng qua qu trnh quang hp. Hai quy trnh lu tr v chuyn ha nng lng mt tri vo nhin liu biomass c th hin nh trong hnh di y:



Hnh 2: Cc ngun nng lng biomass chnh

- Quy trnh 1: Di tc ng ca nng lng mt tri, ngun CO2 v H2O tng hp nn glucozo thnh phn to nn xenlulozo hay tinh bt ca cy xanh thng qua qu trnh quang hp:

6CO2 + 6H2O C6H12O6 + O2 - Quy trnh 2: Cy xanh cht i c phn hy hoc t hnh thnh nn CO2, H2O v bt u mt chu trnh mi:

C6H12O6 + O2 6CO2 + 6H2O Nh vy, ngun nng lng biomass tn ti trong tt c cc loi thc vt.

III. TIM NNG NNG LNG BIOMASS VIT NAM

Vit Nam nm trong khu vc nhit i nng v ma nhiu nn cc loi thc vt pht trin nhanh. Ba phn t lnh th l t rng, sn xut nng nghip chim t trng cao trong nn kinh t nn Vit Nam c ngun nng lng biomass rt ln.

Theo Vin Nng lng B Cng thng [1], tim nng nng lng biomass Vit Nam nh sau:

Hnh 1: Chu trnh chuyn ha v lu tr nng lng mt tri trong nng lng biomass



Bng 1-Tim nng nng lng biomass t g

Ngun Tim nng

(triu tn) Quy du tng ng(triu toe)

T l

(%)

Rng t nhin 6,842 2,390 27,2

Rng trng 3,718 1,300 14,8

t khng rng 3,850 1,350 15,4

Cy trng phn tn 6,050 2,120 24,1

Cy cng nghip v n qu 2,400 0,80 9,6

Ph liu g 1,649 0,580 6,6

TNG 25,090 8,780 100,0

Bng 2- Tim nng nng lng biomass t ph phm nng nghip

Ngun Tim nng(triu tn) Quy du tng

ng (triu toe)

T l

(%)

Rm r 32,52 7,30 60,4

Tru 6,50 2,16 17,9

B ma 4,45 0,82 6,8

Cc loi khc 9,00 1,80 14,9

TNG 53,43 12,08 100,0

IV. CC CNG NGH PHT IN S DNG NNG LNG BIOMASS

- Phng php t trc tip - Direct Combustion: l cng ngh t cc nguyn liu trc tip to ra nhit nng. Nguyn liu t l rt a dng nh g,

rc thi, rm r, v kh sinh hc. Nhit to ra c th c s dng si m khng gian (v d, h thng si ca cc ta nh), nu n v cng c th c s dng un si nc, to ra hi nc s dng cho chy tuabin pht in.

Hnh 3: Quy trnh c bn h thng t chy trc tip sinh in t nng lng biomass

- ng t Cofiring: Cofiring l qu trnh t chy ca hai hay nhiu nhin liu khc nhau trong cng mt h thng t. Nhin liu s dng c th

l nhin liu rn, nhin liu lng hoc kh. i vi h thng nng lng biomass, thng s dng nguyn liu hn hp biomass v than :



Hnh 4: Cng ngh ng t Cofiring than v biomass

Li ch ca cng ngh ng t cofiring than + Biomass:

+ Gim nhim mi trng do gim lng kh thi CO2, SOx v NOx

+ em li hiu qu kinh t do gi thnh nguyn liu biomass r hn than .

+ Cng ngh ny cho php s dng nhiu ngun nguyn liu khc nhau nn mt thit b c sn, cng c th s dng ngun nguyn liu biomass mi m khng cn phi thay i dy chuyn thit b, do vy tit kim chi ph thit k ch to thit b pht in.

- Biofuel Ethanol: Tinh bt c trong ng, khoai ty, c ci ng, ma, la m, la mch, c th c chuyn thnh ru (ethanol) qua qu trnh ln men. Nguyn liu sn xut ethanol cn c th ly t ngun xenlulozo c trong g v cy trng tng hp ln. Ethanol thng c s dng cho cng nghip ha cht, song n cng c th s dng lm nguyn liu t trong cc ng c t trong v tuabin my pht in. Tuy nhin ng dng pht in ca n li nm trong quy trnh sn sut ethanol: song song vi qu trnh sn xut ethanol, qu trnh cn to ra nguyn liu t cht g c trong ng, khoai ty, c ci ng, ma, la m, la mch dng sn xut in.

Hnh 5: S quy trnh sn xut ru ethanol v tn dng ph phm cht g pht in



- Kh ha Gasification: l qu trnh t chy ngun nguyn liu biomass trong mi trng thiu xi sn sinh ra cc cht kh d chy bao gm Carbon monoxide (CO), hydro (H2) v mt phn kh metan (CH4). Hn hp ny c gi l hn hp kh chy (ti liu nc ngoi thng vit l producer gas - sinh kh). Hn hp kh chy c th c s dng chy ng c t trong (c loi ng c nn cao p v loi ng c nh la), cng c th c s dng sn xut methanol (CH3OH) - nhin liu cho ng c nhit cng nh l nguyn liu cho ngnh cng nghip ha cht v quan trng l nguyn liu cho h thng my pht in thng qua ng c t trong to cng c hc lm quay my pht to ra ngun in.

Hnh 6: Chu trnh h thng kh ha gasification

Hnh 7: S nguyn l cng ngh mt h thng kh ha pht in c nh

V. NGUYN L CNG NGH KH HA GASIFICATION

Vi quy m nh, hiu sut cao, h thng pht in kh ha gasification ang l cng ngh hin i v ph hp vi tim nng biomass Vit Nam. Trong phn ny s gii thiu cng ngh kh ha gasification biomass to ra t hp kh gas cp

cho ng c t trong chy my pht in quy m cng sut nh cho cc h gia nh v cc c s ch bin nng lm sn, ph hp vi iu kin Vit Nam.

Cc qu trnh din ra trong b kh ha (Gasifer) gm 4 giai on: Lm kh, nhit phn, t chy v sinh kh.



Hnh 8: Bn qu trnh kh ha nguyn liu biomass

Qu trnh lm kh Drying: y l qu trnh lm kh nguyn liu biomass th di tc dng ca nhit. Nhit cung cp y c thc hin trong mt chu trnh nhit ng hc khp kn ca h thng l kh ha din ra trong quy trnh t kh ha. Tng lm kh t trn tng nhit phn (Pyrolysis). Thnh phn ha hc tng qut ca nguyn liu biomass l CxHyOz:

ot

x y Z 2 x y Z 2C H O .nH O C H O nH O + Qu trnh nhit phn Pyrolysis: y l qu trnh oxi ha khng c xi khng kh di tc dng ca nhit cao. Nhit c cung cp tng t chy trong l kh ha. Tng nhit phn t gia tng t chy (Combustion) v tng lm kh:

ot

x y Z 2 2 2C H O C CO H CO H O + + + + + Tp cht

Sau qu trnh nhit phn thnh phn ch yu l than (C) v h thng kh v hi (CO + H2 + CO2 + H2O) v nhng tp cht vi thnh phn nguyn t ha hc khc nh H2S.

Qu trnh t chy Combustion: Qu trnh t chy c thc hin tng t c ng ng dn

khng kh cha xy vo v t chy hn hp C + CO + H2 + CO2 + H2O. Sn phm kh sau khi t s ch cn li l CO2 + H2O v mt phn kh N2 trong khng kh c th c coi l kh tp cht (s c lm sch trong h thng lm ngui v lc sau h thng l kh ha Gasifer):

2O

2 2 2 2 2C CO H CO H O CO H O++ + + + +

Mt phn C rn nng khng chy ht c chuyn sang tng nn pha di.

Qu trnh sinh kh Reduction: y l qu trnh thc hin trong tng sinh kh ca l kh ha. Cc kh CO2 + H2O sau qu trnh t c dn qua than nng (ca qu trnh nhit phn lng xung) thc hin quy trnh phn ng ha hc to ra kh t chy CO v H2:

ot

2 2 2CO H O 2C 3CO H+ + + Nh vy sau khi qua l kh ha, h thng kh thu c gm cc kh t CO + H2 v mt phn kh tp cht. Hn hp kh ny sau khi qua h thng lc v lm ngui s ch cn kh CO + H2 v c chuyn ti my pht in tuabin kh t v sinh in. Qu trnh sinh kh ny l hon ton t ng.



Cc phn ng ha hc chnh c tng hp trong bng di y:

Giai on kh

ha Phng trnh phn ng

(S phn ng)/

Loi phn ng

Nhit phn ng

KJ/Kmol

Lm kh ot

x y Z 2 x y Z 2C H O .nH O C H O nH O + (1) hir ha



Hnh 9: Gii nhit qu trnh t chy, nhit phn v kh ha

Mt s my pht in cng sut nh trn th gii hin c thng mi ho:

My pht in Xuzhou Renhe New Energy Co., Ltd. ca Trung Quc cng sut 2-5kW

My pht in nhit kh ha Victory Gasifier cng sut 5-15 kw in, 3 kw nhit ca cng ty Victory Gasworks, M



My pht in GEK Power Pallet ca Th Nh K cng sut 10-20kW

VI. KT LUN

Bi bo trnh by mt cch tng qut nht v cc cng ngh ng dng s dng nguyn liu biomass pht in trn th gii hin nay, vi quy m cng sut nh cho h gia nh v cc c s ch bin nng lm sn. Cng ngh kh ha c hiu sut cao, thit b gn nh, c th nghin cu v ch to trong nc ph hp vi nhu cu pht in cng sut nh, thch ng vi ngun nng lng biomass Vit nam. Loi thit b hin ang c Vin Thu in v Nng lng ti to trin khai nghin cu ch to khai thc hiu qu cc ngun biomass sn c nc ta, gp phn b sung mt phn nng lng in nng cho quc gia, ng thi

gp phn bo v mi trng, tng thm thu nhp cho ngi dn v c th bn c cc ph phm nng lm nghip. TI LIU THAM KHO [1]http://www.khihoa.com/2011_12_01_archive.html[2]http://wiki.gekgasifier.com/w/page/6123718/FrontPage.[3]J.B.Jones&G.A.Hawkins:EngineeringThermodynamics,1986,p.456.[4http://www.instructables.com/id/BuildingtheGEKGasifierinsevenparts

Ngi phn bin: PGS.TS Nguyn V Vit

Bnh tip nhin liu trong

Bnh lc th

Bnh lc tinh

Bnh t, ni xy ra cc phn ng nhit h h

Ca ra tro

B my di ng

Documents

Bai a. Viet_So 12