Engr arie *herese Bernadette 'ales PhD ChE+, Proessor ChE Department Chairperson
.$tober / 01+2
I. INTRODUCTION
% bio-sugar and bio-energy $ompany Roxas 3oldings 4n$ is the largest integrated sugar business in the Philippines 5ith $lose to a $entury o experien$e *his industry produ$es millions o tons o sugar e"ery year % by-produ$t o this pro$essing is bagasse, the material (largely $ellulose) that remains ater sugar $ane has been milled and the sugar remo"ed !arge 6uantities o bagasse are produ$ed o"er the period during 5hi$h the sugar is being extra$ted rom the sugar $ane stored on site or an extended period and e"entually used as uel or the sugar mills oten in the next milling season *his paper o$uses on the problems regarding the storage and handling o bagasse 5hen storage is prolonged or o-season po5er generation and en"ironmental impa$ts o bagasse 5hen it has undergone $ombustion or ueling the operations in the industry
II. CO!"N# !RO$ILE Overvie%
Roxas 3oldings 4n$ (R34) is a bio-sugar and bio-energy $ompany 4t operates the largest milling operations in the Philippines as 5ell as the se$ond largest sugar rener and one o the pioneering bioethanol plants in the $ountry Roxol Bioenergy Corporation based in !a Carlota City 7egros .$$idental is the bioethanol unit o R34 4t operates as a stand-alone ethanol produ$tion a$ility 4t produ$es +11111 liters o uel ethanol or potable and industrial al$ohol per day During the year +889 R34 a$6uired maority o5nership o $entral %;u$arera de la Carlota 4n$ oreo"er in the year 01++ Roxol Bioenergy Corporation ran ully on a $ommer$ial basis Co&'any Na&e( R.<.! Bioenergy Corporation
largest "ffiliation( Roxas 3oldings 4n$ the se$ond produ$er o reined sugar as 5ell as the irst ully integrated sugar mill and bio-ethanol distillery $omplex in the $ountry 4t produ$es sugar at its Central %;u$arera de la Carlota 4n$ in !a Carlota and the Central %;u$arera Don Pedro 4n$ mills in Batangas (http:==555rhi-$adp$omph= %ugust +2 01+2) !lant Site( *he plant is built next to Central %;u$arera de !a Carlota 4n$ (C%C4) in !a Carlota City a sugar mill o5ned by Roxas 3oldings 4n$ $irst Co&&ercial O'eration( #une 01+1
!o%er So)rce( Bagasse->ired Boiler 5hi$h $an produ$e 2? 5orth o po5er but only uses 0? or the plant@s energy $onsumption $eedstoc*( olasses a byprodu$t o sugar produ$tion or the produ$tion o Bioethanol
Bagasse a byprodu$t o sugar produ$tion as uel or boiler operations
$eedstoc*s are fro& their + s)gar &ills( Central %;u$arera de !a Carlota 4n$ Central %;u$arera Don Pedro 4n$ in Batangas and an ailiate $ompany 3a5aiianPhilippine Company in 7egros .$$idental (http:==555alternat+"e$om=biouel=0119=1,=/1=roxol-bioenergy-$orp-to-build-ethanoldistillery-in-negros-o$$idental= %ugust +2 01+2) O'erating Cycle ,asis( +1 onths Chief O'erating Officer and Ro-ol !resident( !uis . Ailla-%brille Ca'acity( *he plant produ$ed +1 million !iters o Bioethanol rom .$tober 01+/ to ar$h 01+2 but Roxol has the $apa$ity to produ$e /1 million liters o ethanol a year or around +11111 liters a day (http:==555sunstar$omph=ba$olod=business=01++=+1=+=roxol-a5aits-reeren$epri$ing-lo$al-ethanol-+9+8/ %ugust +2 01+2) $acilities and E)i'&ent(
+ >ermentation and Distillation in ethanol produ$tion 0 ?aste5ater *reatment >a$ilities / 'lops Con$entration 2 Produ$t 'torage 'team Boiler and , *urbo-enerator Components !lant Cost( *he setting up o a turney bioethanol plant amounted to about PhP+ billion *he turney and the boiler problems amounted total to PhP+,-billion (http:==businessin6uirernet=0+9,/=negros-bioethanol-plant-no5-ully-operational %ugust +2 01+2) !lant Contractor( &B& Chemi$al Engineering P"t !td a subsidiary o 4ndia@s 'hree Renua 'ugars !imited
Co&'any /istory 0ilestones 1234 5 Established as a sugar milling $ompany in 7asugbu Batangas and 5as then no5n as Central %;u$arera Don Pedro 122 5 *he roup embared on an expansion and moderni;ation program 5hi$h enabled R34 to be$ome an integrated sugar manua$turing $ompany 5ith a reinery 1227 5 4t a$6uired maority o5nership o Central %;u$arera de la Carlota 4n$ (C%C4) 3883 5 *he $ompany $ommen$ed a $orporate reorgani;ation program to transorm itsel into a holding and in"estment $orporation resulting in the integration o its sugar businesses under a single subsidiary no5n as C%DP roup Corporation (C%DPC) 3887 5 *he Roxas roup under5ent a $orporate reorgani;ation that separated its sugar and real estate businesses into t5o irms listed 5ith the Philippine 'to$ Ex$hange (P'E) 3811 5 Roxol Bioenergy Corporation the bioethanol unit o R34 ran ully on a $ommer$ial basis
III. !RO,LES "ND SOLUTIONS ". Storage 'ro9le&s for 9agasse as it s'ontaneo)sly co&9)sts 01 and Lo% Calorific val)e of 9agasse d)e to high &oist)re content 03
*he storage o bagasse 5hi$h is prin$ipally $ellulose presents many problems or the sugar industry one o 5hi$h is bagasse loss due to spontaneous $ombustion *his is an expensi"e problem or the industry as bagasse $an be used as a uel and or $ogeneration o ele$tri$ity 'el-heating o$$urs in the pile through an oxidation me$hanism as 5ell as a moisture dependent rea$tion Bagasse typi$ally $ontains 2F by 5eight o 5ater 5hen milling is $ompleted and the 6uestion o ho5 to redu$e the moisture $ontent is important or t5o reasons >irstly 5et bagasse does not burn nearly as ei$iently as dry bagasse and se$ondly sel-heating is greatly enhan$ed in the presen$e o 5ater or temperatures less than ,1-1GC (?hyH) Dry bagasse 5hi$h burns at a higher temperature is a superior uel to 5et bagasse 3o5e"er be$ause near-boiling 5ater is used to remo"e the last o the sugar rom the $ane 5hen bagasse lea"es the sugar mill it has a 5ater $ontent o up to F by 5eight and a temperature around 1GC Conse6uently as 5et bagasse does not
burn nearly as ee$ti"ely or ei$iently as dry bagasse burning as it does at a lo5er temperature ha"e e$onomi$ and en"ironmental $osts 'to$piling 5et bagasse riss spontaneous ignition o the pile or the lea$hing o noxious a$ids into the surrounding earth Clearly then understanding the 5ay in 5hi$h bagasse heaps dry out is an extremely important issue or the sugar industry >urthermore it is desirable to use the sel-heating o the bagasse pile to enhan$e the redu$tion o moisture $ontent during storage 5hile at the same time ensuring that spontaneous $ombustion $annot o$$ur ?et $ellulose 5hi$h is the prin$ipal $omponent o bagasse ignites more easily than dry $ellulose Re$ent experimental 5ors demonstrate that $ellulose undergoes an exothermi$ rea$tion 5ith 5ater at moderate temperatures *his rea$tion is thought to be possibly o a hydrolyti$ nature though it is not 5ell understood at present *ypi$ally the mill 5et bagasse $ontains around 29F to 0F moisture 5ith a gross $alorii$ "alue (CA) o around 001 &$al=g (I811 =g) 7ormally the bagasse is dire$tly ed to the boiler to generate steam and surplus bagasse is stored in the bagasse yard *he boiler installed in the plant are designed to burn bagasse 5ith this moisture 4t is a no5n a$t that CA o bagasse is largely dependent upon its moisture $ontent 3igher moisture $ontent in bagasse redu$e its CA and also results in higher energy loss be$ause the uel moisture $arries that latent heat o "apori;ation up the sta$*he CA o bagasse $an be determined $an be determine by the ollo5ing e6uation J CAK+LM +8,1 x (+11-?5 F - ?% F) J /++2 x ?RD' N &#=g ?here ?5 - is the moisture $ontent ?% - is the ash $ontent ?RD' - is the Brix %s $an be seen rom the abo"e e6uation the CA o bagasse sho5s a de$rease o +8,&#=g (2&$al=g) or e"ery +F in$rease in moisture
!ro'osed Sol)tions(
(+) 'torage problems or bagasse as it spontaneously $ombusts: a Design sto$piles to redu$e exposure to pre"ailing 5inds and to minimi;e rain5ater ingress b 4nstall and monitor ele$troni$ systems= spar arrestors to pro"ide early dete$tion o $hanges in sto$pile temperatures (0) !o5 Calorii$ "alue o bagasse due to high moisture $ontent: Design o a bagasse dryer 5ith the ollo5ing $onsidered parameters: a 3eat transer rate should be high b Retention time should be short be$ause bagasse is sus$eptible to ire $ Drying should be uniorm d *he dryer should not re6uire spe$ial maintenan$e and $an be put in and out o operation 5ithout disturbing the boiler and does not re6uire any extra manpo5er or operation ,. ,agasse co&9)stion i&'oses environ&ental restrictions
Bagasse is a 5aste produ$t o the sugar $ane extra$tion pro$ess and represents about /1F o the 5eight o the ra5 sugar $ane 4n order or the sugar $ane mill to a"oid a large solid 5aste disposal problem and to minimi;e the $ost o po5er re6uirements the bagasse is used as the primary uel or on-site steam produ$tion Biomass is a readily a"ailable rene5able resour$e that has been used throughout the past as a sour$e o heat energy by means o $ombustion and Roxol Bioenergy Corporation has been using bagasse to uel their boilers 3o5e"er it is a 5ell-established a$t that $ombustion o solid uel or po5er generation is a signii$ant $ontributor to global 5arming 3en$e the group proposed a pro$ess o redu$ing the ris a$tors in the en"ironment and maes possible the use o higher ei$ien$y $ombined $y$le systems or po5er generation
!ro'osed Sol)tion(
Bagasse 5ill be sube$ted to a thermal re$o"ery pro$ess Bagasse is irst shredded and blended %s a matter o a$t Roxol Bioenergy Corp $an mae use o other solid 5aste materials that are mostly ound in landills as eed to this pro$ess 3en$e i there 5ill be shortage o bagasse sto$s other 5astes $an be an alternati"e 4t
is then ed through an airlo$ system to ensure an oxygen dei$ient en"ironment in a retort $hamber *his pro$ess is no5n as pyrolysis *he 5aste materials 5ill be exposed to temperatures o up to +1+1OC *he bio-mass remains in the retort $hamber until all "olatile material is pro$essed 4t is then dire$ted through the transition ;one 5here gas $onditions are monitored to ensure optimal perorman$e >rom here the gases are pulled into the thermal oxidi;er 5here they are mixed 5ith oxygen and $ombusted *oxi$ and noxious 5astes are eliminated at this point and the high temperatures o the thermal oxidi;er result in harmless emissions mostly in the orm o $arbon dioxide and 5ater "apor Energy produ$ed rom thermal oxidi;er is dire$ted to the boiler *hen it produ$es steam to uel their operations *he ex$ess "apors produ$ed $an be $ondensed to orm uel oil 5hi$h 5ill be stored or uture use *his pro$ess also produ$es remaining solids $alled $har and is dis$harged through the dis$harge airlo$ *hese solids $an be used as soil $onditioner or agri$ulture as it impro"es the soil un$tion assists 5ith the retention o moisture and redu$es soil a$idity *hese are useul ertili;ers or their sugar$ane $rop produ$tion 4n $on$lusion the o"er-all pro$ess is gi"ing them t5o-5ay beneits
I:. DOCUENT"TION
:. CONCLUSION
Bagasse under $ertain $ir$umstan$es demands negati"e impa$ts in terms o plant operations and saety and en"ironmental aspe$t as 5ell Be$ause o this it needs to be gi"en due noti$e and sustainable planned a$tions
