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SAI VIDYA INSTITUTE INSTIT UTE OF TECHNOLOGY Rajanakunte, Rajanakunte, Bangalore-560064 Bangalore-560064 DEPARTMENT OF MECHANICAL ENGINEERING INTERNAL ASSESSMENT: III VIII SEM, ME MAX MARS : 50
SUBJECT: BIOMASS ENERGY SYSTEMS
DATE: /0 /05/2016
SUB CODE: 10ME!"#
TIME: 1$#0PM % #$00PM
Note: Answer Answer any FIVE full questions, choosing at least &'( questions from each part. PART)A 1 2
3 4
What is Ethanol? With the help of flow chart eplain the pro!uction of ethanol form sugar cane. With the help of neat s"etches, state the mo!ifications necessary for #I an! $I Engines for use of %io&gas.
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With a neat flow chart, eplain the pro!uction of ethanol from woo! 'y aci! hy!rolysis.
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state the (arious effect of using 'io&!iesel in I.$.engines
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SAI VIDYA INSTITUTE INSTIT UTE OF TECHNOLOGY Rajanakunte, Rajanakunte, Bangalore-560064 Bangalore-560064 DEPARTMENT OF MECHANICAL ENGINEERING INTERNAL ASSESSMENT: III VIII SEM, ME MAX MARS : 50
SUBJECT: BIOMASS ENERGY SYSTEMS SUB CODE: 10ME!"#
DATE: /0 /05/2016 TIME: 1$#0PM % #$00PM
Note: Answer Answer any FIVE full questions, choosing at least &'( questions from each part. PART)A 1
What is Ethanol? With the help of flow chart eplain the pro!uction of ethanol form sugar 1 cane. 0
CO 1
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3 4
With the help of neat s"etches, state the mo!ifications necessary for #I an! $I Engines for 1 0 use of %io&gas.
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With a neat flow chart, eplain the pro!uction of ethanol from woo! 'y aci! hy!rolysis. state the (arious effect of using 'io&!iesel in I.$.engines
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PART)B 5 6 7 8
E*+-. D.&3 D. C(.43-&.(
)ow 'io!iesel is pro!uce! from e!i'le an! non&e!i'le oils. *escri'e 'riefly %rayton cycle, #terling cycle, +an"ine cyle, With a neat s"etch, !escri'e a 'io&mass 'ase! steam power plant
CO1. The fundamentals of residual biomass and energy crops. CO2. The fundamentals of biomass conversion processes and devices
PART)B 5 6 7 8
E*+-. D.&3 D. C(.43-&.(
)ow 'io!iesel is pro!uce! from e!i'le an! non&e!i'le oils. *escri'e 'riefly %rayton cycle, #terling cycle, +an"ine cyle, With a neat s"etch, !escri'e a 'io&mass 'ase! steam power plant
CO1. The fundamentals of residual biomass and energy crops. CO2. The fundamentals of biomass conversion processes and devices
5$ E*+-. D.&3
D. C(.43-&.(
*igester *esign $onsi!erations *igestion tan"s may 'e of any con(enient shape an! pro(i!e! with a co(er to retain the gas. he co(er may 'e a fie! one or floating. A num'er of factors are to 'e ta"en into account to arri(e an optimum si-e of a 'iogas plant. hese are . he (olume of waste to 'e !igeste! !aily, /. he type an! amount of waste a(aila'le for !igestion consistently, 0. 1erio! of !igestion, 2. 3etho!s of stirring, the contents if any, 4. 3etho! of a!!ing the raw waste an! remo(ing !igeste! slurry, 5. Efficiency of collection of the raw waste, 6. he climate con!ition of the region, 7. he a(aila'ility of other cellulosic fermenta'le waste in that area, 8. Information a'out su'&soil con!ition an! water ta'le, an! 9. ype of the co(er. he capacity of the !igestion tan" may 'e formulate! is as
he require! capacities of !igestion tan"s may 'e calculate! on the 'asis of !estruction /0 of the organic matter in slurry an! the con(ersion of 2 of what is !estroye! into mineral matter an! the remaining to gases. he perio! of !igestion;t< is fie! 'y the time necessary to pro!uce a satisfactory !igeste! slu!ge. his !epen!s on mainly upon the temperature of !igestion It is well "nown fact the pro!uction of 'iogas through anaero'ic !igestion of the 'iomass is !epen!ent on the temperature. he pro!uction slows !own consi!era'ly 'elow /9=$ In the mesophilic range the usual of gas pro!uction in the In!ian 'iogas plants, methanogenic 'acteria grow 'est at temperatures of 00 9 & 29=$ he rate of gas pro!uction approimately !ou'les up for e(ery 9=$ rise in temperature 'etween 4=$ an! 04=$ an! !ou'les 'etween 04=$ an! 44=$ >thermophilic range. )ence a !igester operating at 4=$ has to ha(e a (olume four times greater than the one at 04=$ an! eight times the one at 44=$ to yiel! the same !aily pro!uction of the !igester. For su'&soil con!ition an! high water ta'le areas, mo!ifications in !esign are nee!e!. If the clay type soils maimum shrin"age of soil is possi'le an! hence at an inter(al of 5 cm height one concrete ring structure aroun! the !igester might help in strengthening the !igester.
he @anesh mo!el of 'iogas plant in which 2 to 4 well rings of sufficient !iameter are place! one o(er the other an! cemente! together at the oints seems to wor" well in areas comprising of san! y soil.
In high water ta'le areas, the *een'an!hu mo!el whose entire structure goes upto ./ to .4 m 'elow groun! le(el is quite suita'le.
%esi!es this, construction of plants a'o(e groun! with usual 'ac"ing an! soil grouting might also 'e consi!ere! in such areas. A lea"&proof two&wall system with aqua&proof cementing might also help in enhancing the gas output . For operation of the !igester in the thermophilic range, the temperatures are require! to he maintaine! at
nearly constant (alue 'ecause the thermophilic 'acteria are highly sensiti(e to fluctuation in the temperature. R&&.( &. !epen!s on the climatic con!itions, an! so si-e of the !igester. For hot, tropical prone
climate, 09 to 29 !ays retention time woul! 'e sufficient. In hot regions with a perio! of winter, the retention time may ha(e to 'e 29 to 59 !ays. In temperature climate with a !efinite !rop in temperature !uring the winter, the retention time may 'e 59 to 89 !ays. Accor!ing to these factors the requirement of gas will ha(e to 'e wor"e! out an! this has to 'e tallie! with the a(aila'ility of fee! materials to !eci!e the si-e of capsule mo!ule. S.&-7..&8 (9 R-' M-&3.-$ If the a(aila'ility of clung is less an! will meet the userBs fertili-ers
requirements 'ut lea(e 3in short of gas then he can su'stitute a portion of (egeta'le waste for an equal amount of !ung >!ry his will ena'le him to get more gas for the same amount of fertili-er. In such cases it is necessary to maintain $N ratio. his ratio shoul! 'e maintaine! 'etween 09 an! 04 'y properly (arying the quantities of other 'io!egra'le materials. Normally the weight of !ung in a !ung (egeta'le miture shoul! 'e maintaine! a'o(e 49C. he amount of !ry soli!s in cow!ung is 7C. he nitrogen content in !ry !ung is .6C, an! car'on content is /4 times that of nitrogen.he ultimate concentration of soli!s in the slurry shoul! 'e 'etween 6 an! 8C. V( (9 D.&3 9(3 B.(- P3(4&.( . $ow !ung only. At 4=$, "g of !ry !ung gi(es 9.75
m0 of gas. he ratio of !ry !ung to water in wet !ung is : 2. Normally "g of wet !ung is mie! with "g of water to get the slurry. he !uration of each cycle !e pen!s on the temperature. )ence if the gas requirement an! !uration of cycle are "nown, then the amount of water an! !ung nee!e! can 'e estimate!. he (olume of the !igester is equi(alent to the (olume of slurry. A gas space of 9C of this (olume coul! 'e pro(i!e! in the !igester. )ence the total (olume of the !igester can 'e ta"en as . times the (olume of the slurry. ;$D3.7 73.98 B3-8&( 8, S&3. 8, R-<. 8,
S&.3. C8 &.3. 8 is a thermo!ynamic cycle consists of two isothermal an! two isochoric processes. )eat reection an! heat a!!ition ta"es place at constant temperature.
P33)=( -4 T+3-&3)&3(+8 4.-3-
Where, &/: Isothermal compression /&0: $onstant (olume cooling 0&2: Isothermal eoansion 2&: $ontant (olume heating From the p&V an! &s !iagram of stirling cycle it is clear that the amount of heat a!!ition an! heat reection !uring constant (olume is same. )eat supplie! D Wor" !one !uring isothermal epansion
)eat reecte! 'y the air !uring isothermal compression
Wor" !one D heat supplie! heat reecte! hermal efficiency can 'e gi(en 'y the equation
B3-8&( C8
he air&stan!ar! %rayton cycle is a theoretical cycle for gas tur'ines. his c ycle consists of two re(ersi'le a!ia'atic or isentropic processes an! two constant pressure processes. his thermo!ynamic cycle is represente! on p&V an! &s coor!inates, is similar to !iesel cycle in compression an! heat a!!ition. he isentropic epansion of !iesel cycle is further eten!e! followe! 'y constant pressure heat reection.
+)V -4 T) 4.-3- 9(3 &> -.3)&-4-34 B3-8&( 8
Where, &/: Isentropic process /&0: Iso'aric process 0&2: Isentropic 1rocess 2&: Iso'aric process hermal Efficiency can 'e calculate! 'y the formula
Where ;"< is the specific heat ratio $ p$(.
Simple Rankine Cyle
T> .+ R-<. 8 . -( - 3=3.7 8$
$onsi!er the i!eali-e! four&stea!y&state&process cycle in which state is saturate! liqui! an! state 0 is either saturate! (apor or superheate! (apor. his system is terme! the +an"ine cycle an! is the mo!el for the simple steam power plant. It is con(enient to show the states an! processes on a s !iagram, he =-3.( +3( . .+ R-<. 8 are: /: +e(ersi'le a!ia'atic pumping process in the pump, /0: $onstant&pressure transfer of heat in the 'oiler, 02: +e(ersi'le a!ia'atic epansion in the tur'ine >or other prime mo(er such as a steam engine, 2: $onstant&pressure transfer of heat in the con!enser.
F.3 2: T+3-&3 = &3(+8 4.-3- (9 R-<. 8 < he +an"ine cycle also inclu!es the possi'ility of superheating the (apor, as cycle /0 2<.
If "inetic an! potential energy changes are neglecte!, heat transfer an! wor" may 'e represente! 'y (arious < areas on the s !iagram. he heat transferre! to the wor"ing flui! is represente! 'y area a// 0'a an! the heat transferre! from the wor"ing flui! 'y area a2'a. From the first law we can conclu!e that the area < representing the wor" is the !ifference 'etween these two areasarea // 02. he thermal efficiency is !efine! 'y the relation
7. With a neat s"etch, !escri'e a 'io&mass 'ase! steam power plant BIOMASS BASED STEAM PO?ER PLANT DESCRIPTION
3ost 'iopower plants use !irect&fire! com'ustion systems. hey 'urn 'iomass !irectly to pro!uce high& pressure steam that !ri(es a tur'ine generator to ma"e electricity. In some 'iomass in!ustries, the etracte! or spent steam from the power plant is also use! for manufacturing processes or to heat 'uil!ings. hese com'ine! heat an! power >$)1 systems greatly increase o(erall energy efficiency to approimately 79C, from the stan!ar! 'iomass electricity&only systems with efficiencies of approimately /9C. #easonal heating requirements will impact the $)1 system efficiency. A simple 'iomass electric generation system is ma!e up of se(eral "ey components. For a steam cycle, this inclu!es some com'ination of the following items: • • • •
Fuel storage an! han!ling equipment $om'ustor furnace %oiler 1umps
• • • • • • •
Fans #team tur'ine @enerator $on!enser $ooling tower Ehaust emissions controls #ystem controls >automate!. *irect com'ustion systems fee! a 'iomass fee!stoc" into a com'ustor or furnace, where the 'iomass is 'urne! with ecess air to heat water in a 'oiler to create steam. %oiler fuel can inclu!e woo! chips, pellets, saw!ust, or 'io&oil. #team from the 'oiler is then epan!e! through a steam tur'ine, which spins to run a generator an! pro!uce electricity. In general, all 'iomass systems require fuel storage space an! some type of fuel han!ling equipment an! controls. A system using woo! chips, saw!ust, or pellets typically use a 'un"er or silo for short&term storage an! an outsi!e fuel yar! for larger storage. An automate! control system con(eys the fuel from the outsi!e storage area using some com'ination of cranes, stac"ers, reclaimers, front&en! loa!ers, 'elts, augers, an! pneumatic transport. 3anual equipment, li"e front loa!ers, can 'e use! to transfer 'iomass from the piles to the 'un"ers, 'ut this metho! will incur significant cost in la'or an! equipment operations an! maintenance . Woo! chip&fire! electric power systems typically use one !ry ton per megawatt&hour of electricity pro!uction. his approimation is typical of wet woo! systems an! is useful for a first approimation of fuel use an! storage requirements 'ut the actual (alue will (ary with system efficiency. 3ost woo! chips pro!uce! from green lum'er will ha(e a moisture content of 29C to 44C, wet 'asis, which means that a ton of green fuel will contain 799 to ,99 poun!s of water. his water will re!uce the reco(era'le energy content of the material, an! re!uce the efficiency of the 'oiler, as the water must 'e e(aporate! in the first stages of com'ustion. he 'iggest pro'lems with 'iomass&fire! plants are in han!ling an! pre&processing the fuel. his is the case with 'oth small grate&fire! plants an! large suspension&fire! plants. *rying the 'iomass 'efore com'usting or gasifying it impro(es the o(erall process efficiency, 'ut may not 'e economically (ia'le in many cases. Ehaust systems are use! to (ent com'ustion 'y&pro!ucts to the en(ironment. Emission controls might inclu!e a cyclone or multi&cyclone, a 'aghouse, or an electrostatic precipitator. he primary function of all of the equipment liste! is particulate matter control, an! is liste! in or!er of increasing capital cost an! effecti(eness. $yclones an! multi&cyclones can 'e use! as pre&collectors to remo(e larger particles upstream of a 'aghouse >fa'ric filter or electrostatic precipitator. In a!!ition, emission controls for un'urne! hy!rocar'ons, oi!es of nitrogen, an! sulfur might 'e require!, !epen!ing on fuel properties an! local, state, an! Fe!eral regulations. H(' D( .& ?(3<@
In a !irect com'ustion system, 'iomass is 'urne! in a com'ustor or furnace to generate hot gas, which is fe! into a 'oiler to generate steam, which is epan!e! through a steam tur'ine or steam engine to pro!uce mechanical or electrical energy.
In a !irect com'ustion system, processe! 'iomass is the 'oiler fuel that pro!uc es steam to operate a steam tur'ine an! generator to ma"e electricity.
