07_srivastava

7/28/2019 07_srivastava

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BRIQUETTING OF CROP RESIDUES WITHSPECIAL REFERENCE TO COTTON STALK

MARKET POTENTIAL IN INDIA

N.S.L.Srivastava

Sardar Patel Renewable Energy Research Institute

Vallabh Vidyanagar (Gujarat)

BRIQUETTING TECHNOLOGY

Briquetting is a technology for densification of biomass /crop residues to increase its bulk density, lowermoisture contents, make briquettes of uniform size andshape for easy handling, transport and storage. I t alsohelps in uniform burning when used as fuel.

Briquettes have high specific density, about 1100-1200kg/m3 and bulk density about 600-800 kg/m3 ascompared to loose biomass which have bulk density inthe range of 80-200 kg/m3.

Briquetting can be done with and without binder.

Commercial high capacity machines do not use binders.

At higher temperature (between 100-120 C) the ligninpresent in the biomass is fluidized and acts as its ownbinder. On cooling it solidifies and holds the briquettesintact.

AVAI LABLITY OF SURPLUS CROP AND AGRO -PROCESSING RESIDUES AND THEIR USES

Annually about 477.46 millions tonnes of crop residues includingabout 27 million tonnes of cotton stalk and about 100 milliontonnes of agro-processing residues/ wastes are produced inIndia. This does not include horticultural crop residues andwastes.

Substantial quantities of these residues are used as cattlefeed/fodder, domestic fuel for cooking, construction material forrural housing (thatch), for paper industry and as packingmaterial.

About 100-125 million tonnes, including about 11.8 milliontonnes of cotton stalk, are not used properly and are availableas surplus.

Part of this surplus, specially the rice straw, some quantities ofwheat straw and cotton stalks are burnt in the states of Punjab,Haryana, Western Uttar Pradesh, Uttarakhand, MadhyaPradesh, Gujarat and Maharashtra These could be briquettedand used as fodder in fodder deficit areas and part forcombustion/gasification. Cont.

Continued.

With the increase in productivity of crops, on one hand andreduction in animal population, specially the draught animals,and environmental concerns regarding burning of straw on theother hand, the availability of biomass for briquetting will bemuch more from the present position.

By the year 2015 about 700 million tonnes of crop and agro-processing residues/wastes are likely to be available annually outof which about 300 million tonnes, including, 13 MT of cottonstalk, would be surplus.

If the surplus biomass is briquetted as such or after fortification(for animal feed), its handling, storage and transport becomeseconomical and much easier and the briquettes can be used asfeed and fodder for animals or as domestic and industrial fuel forenergy.

Cont.

Continued.

Briquetted feed stocks can be transported to fodder deficitareas for creations of Fodder Banks.

High density briquettes are used in boilers, gasifiers, furnacesand domestic cook stoves.

The calorific value of crop/agro-processing residues varybetween 3100 - 4500 kcal/kg. I f used for power generation 1 kgof such residues can give about 1 kWh of electrical energy.

It is visualized that in future there will be greater demand forbriquetting of surplus biomass in India for feed, fodder andenergy.

UNIT OPERATIONS INVOLVED IN PREPARATION OFDIFFERENT FEEDSTOCK FOR BRIQUETTING

Sr.No.

Feed-stocks Unit operations performed

Sieving Drying Cutting of

branches/chopping

Shredding Grinding

1 Saw Dust - - -

2 Sugarcane

Bagasse

- - -

3 Cotton Stalk - -

4 Groundnut shell - - - -

5 J atropha Shell - - - -

6 Wheat straw

threshed- - - -

7 Rice straw - - -

8 Pearl millet stalk - - -

9 Mustard stalk - - - -

10 Dry leaves - - - -


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a) Cutt ing of branches b) Shredding in a shredder c) Shredded material d) Gr inding in a hammer

mill for powder making

Steps involved in preparation of Cotton Stalk for Briquetting

Briquetting and Pelleting Machines installed at SPRERI

SAW DUST COTTON STALK POWDER

LOOSE SUGARCANE BAGGASE GROUNDNUT SHELL POWDER

JATROPHA SHELL POWDER 50% RICE HUSK POWDER +50% SAW DUST

CHOPPED RICE STRAW CHOPPED WHEAT STRAW

Piston Press TypeBri quetting Machine

Different Types of Feedstock Used For Br iquetting

Rice Husk Briquettes from Screw Press Briquetting Machine

Pelleting Machine CC =Castor cake, SD +Sawdust, SBP +Sugarcanebagassepowder

Pellets of 22 mm size made with differentcombinations of Castor Cake with Sawdust

and Sugarcane Bagasse

Pellets of 10 mmsize made out of

Castor Cake andSawdust in the

proportion of

50:50


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MACHINE FOR MAKING ANIMAL FEED BLOCKS

1.5 t/h Rice straw based briquetting plant for making

animal feed blocks

ENERGY REQUIRED IN GRINDING AND BRIQUETTINGOF DIFFERENT TY PES OF FEED STOCKS

Feedstock Moisturecontent %

Gr inding Br iquetting

Outputkg/h

Energy usedkWh/t

Output**kg/h

Energy usedkWh/t

Saw Dust 10.10 - - 618.83 40.73

SugarcaneBaggase 9.70 169.70 49.01 232.72 60.08

Groundnut Shell 1.21 376.43 15.56 553.50 34.75

J atropha shell 9.30 372.36 16.24 619.00 38.77

Shredded Cotton Stalk 10.39 127.16 81.51 413.70 35.29

Shredded pearl millet stock 12.68 125.67 74.20 295.15 46.52

Mustard stalk 2.10 100.28 62.82 251.86 54.14

Threshed wheat straw 4.58 213.42 43.62 248.49* 52.88*

Chopped ricestraw 7.27 254.10 39.40 228.32* 60.25*

Dry leaves 5.85 100.50 59.70 804.60 20.87

* Br iquetting was donefor a short period only ** Briquetting was doneat 9-12% M C. incaseof all thefeedstocks

PERFORMANCE OF BRIQUETTING PLANT AT SPRERIOUTPUT OF THE BRIQUETTI NG MACHINE ON DIFFERENT TY PES OF FEEDSTOCK

* small scale trials, ** very small scale trials, further work continuing

Feedstock Moisturecontent

%

Bulk density in kg/m3 TrueDensityin kg/m3

Extent ofdensific-ation %

Output**

kg/h

Energyused

kWh/tLoose Powder Briquettes

Saw Dust 10.10 - 240.00 615.00 1140.00 475 618.83 40.73

Suga r c a ne

Baggase

9.70 85.73 133.00 675.00 1100.00 1283 232.72 60.08

G r o undnut

Shell

1.21 168.40 318.00 620.00 1070.00 635 553.50 34.75

S h r ed d ed

Cotton Stalk

10.39 122.26 226.27 631.33 1110.00 2676 413.70 35.29

Shredded pearl

millet stock

12.68 93.60 145.47 538.80 980.00 1047 295.15 46.52

Mustard stalk 2.10 41.47 137.33 677.33 1150.00 2773 251.86 54.14

T h r e s h e dwheat straw

4.58 56.40 118.41 591.06 950.00 1684 248.49 52.88*

Chopped ricestraw

7.27 50.26 112.93 640.00* 1250.00 2487 228.32* 60.25*

Dry l eaves 5.85 37.20 316.53 442.00 950.00 2554 804.60 20.87

J atropha shell 9.30 148.50 287.66 684.70 1000.00 673 619.00 38.77

COST OF BRIQUITT ING OF DIFFERENT TYPES OF BIOMASS

Feed-stocks Fixed cost ofBriquett-ingmachinein

Rs/tonne

Operat ing Cost in Rs/tonne Cost of rawmaterial

in

Rs/tonne

Total cost ofbriquettingincluding

rawmaterial

in Rs/tonne

Siev-ing

Drying Cutting ofbranches/ chopping

Shredd-ing Grinding ActualBriquetting

TotalOperat-ing

cost

When Briquetting Machineis running in oneshift per day (8hrs)

Saw dust 536.36

(26.43%)

29.25

(1.44%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

203.64

(10.04%)

232.89

(11.48%)

1260

(62.09%)

2000.00

(100.00%)

Sugar-

canebagasse

1179.83

(36.31%)

0.00

(0%)

0.00

(0%)

227.50

(7.00%)

0.00

(0%)

701.57

(21.59%)

300.40

(9.25%)

1229.47

(37.84%)

840

(25.85%)

3249.30

(100.00%)

Cotton stalk 714.18

(21.58%)

0.00

(0%)

0.00

(0%)

227.50

(6.88%)

483.33

(14.61%)

657.53

(19.87%)

176.49

(5.33%)

1544.85

(46.69%)

1050

(31.73%)

3309.03

(100.00%)

Pearl millet

stalk

999.25

(32.15%)

0.00

(0%)

0.00

(0%)

227.50

(7.32%)

0.00

(0%)

598.92

(19.27%)

232.62

(7.48%)

1059.04

(34.07%)

1050

(33.78%)

3108.00

(100.00%)

Wheat straw 1187.00(41.59%)

0.00(0%)

0.00(0%)

0.00(0%)

0.00(0%)

352.40(12.35%)

264.40(9.26%)

616.80(21.61%)

1050(36.80%)

2853.80(100.00%)

Groundnutshell

632.52(22.75%)

0.00(0%)

0.00(0%)

0.00(0%)

0.00(0%)

157.45(5.66%)

153.93(5.53%)

311.38(11.19%)

1837.50(66.06 %)

2781.40(100.00%)

Mustard Stalk 1345.34(41.11%)

0.00(0%)

0.00(0%)

0.00(0%)

0.00(0%)

605.99(18.52%)

270.71(8.27%)

876.70(26.79%)

1050.00(32.10%)

3272.04(100.00%)

Dry l eaves 421.13(25.68%)

0.00(0%)

0.00(0%)

0.00(0%)

0.00(0%)

589.74(35.96%)

104.40(6.36%)

694.14(42.32%)

525.00(32.00%)

1640.27(100.00%)

Continue.

Feed-stocks F ixed costof Br iquett-

ing machinein Rs/tonne

Operating Cost in R s/tonne Cost of rawmaterial

inRs/tonne

Total cost ofbriquetting

including rawmaterial

in Rs/tonne

Sieving Drying Cutting ofbranches

/ chopping

Shredd-ing Grinding ActualBriquetting

TotalOperat-ing

costWhen Briquetting Machineis running in two shifts per day (16hrs)

Saw dust 268.14(15.23%)

29.25

(1.66%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

203.64

(11.56%)

232.89

(13.22%)

1260

(71.55%)

1761.03

(100.00%)

Sugar-cane

bagasse

589.92

(22.18%)

0.00

(0%)

0.00

(0%)

227.50

(8.55%)

0.00

(0%)

701.57

(26.38%)

300.40

(11.29%)

1229.47

(46.23%)

840

(31.59%)

2659.39

(100.00%)

Cotton stalk 357.09(12.10%)

0.00

(0%)

0.00

(0%)

227.50

(7.71%)

483.33

(16.37%)

657.53

(22.27%)

176.49

(5.98%)

1544.85

(52.33%)

1050

(35.57%)

2951.94

(100.00%)

Pearl milletstalk

499.62

(19.15%)

0.00

(0%)

0.00

(0%)

227.50

(8.72%)

0.00

(0%)

598.92

(22.96%)

232.62

(8.92%)

1059.04

(40.60%)

1050

(40.25%)

2608.66

(100.00%)

Wheatstraw

593.50

(26.26%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

352.40

(15.59%)

264.40

(11.70%)

614.80

(27.29%)

1050

(46.45%)

2260.30

(100.00%)

Groundnutshell

306.09

(12.47%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

157.45

(6.41%)

153.93

(6.27%)

311.38

(12.68%)

1837.50

(74.85%)

2454.97

(100.00% )

MustardStalk

672.67

(25.88%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

605.99

(23.31%)

270.71

(10.41%)

876.70

(33.72%)

1050.00

(40.40%)

2599.37

(100.00% )

Dry leaves 210.57(14.73%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

0.00

(0%)

589.74

(41.25%)

104.40

(7.30%)

694.14

(48.55%)

525.00

(36.72%)

1429.70

(100.00%)

Use of Cotton Stalk briquettes in an open core gasifier atSPRERI


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A 2,50,000 Kcal/h SPRERI Design Open Core Gasifier installed in an

industry using Wood and Crop Residues Briquettes as feedstock Combustion Studies of Crop Residue Pellets in twodifferent types of Cook Stoves

0

100

200

300

400

500

600

700

800

Time, (min)

JatrophaShellBriquettes

SawDust Briquettes

SugarcaneBaggaseBriquettes

CottonStalk Briquettes

PearlM illet Briquettes

RiceStraw Powder Briquettes

Wheat Strawpowder Briquettes

Variation in flame temperature of briquettes of different

biomass with respect to time

ENERGETICS OF BRIQUETTING CROP RESIDUESAND OTHER BIOMASS FOR ENERGY PURPOSES

The total energy used in baling, transport of crop residues,drying, grinding and actual briquetting comes to about8.35-10.96 % of the electrical energy which could beproduced from that crop residue.

For thermal purposes these figures will be only about 2.08-2.74%. If instead of crop residues, saw dust or groundnutshells are used as biomass, in which case energy for balingand grinding will not be required, these figures will beabout 7.26- 9.59% and 1.30-2.05% respectively.

Energetics of using crop residue and other biomass briquettesfor energy purposes, both, thermal and power shows that

ISSUES INVOLVED IN PROMOTION OF BRIQUETTINGTECHNOLOGY

Need for reliable assessment of annual availability of cropand agro-processing waste in different regions and seasons.

Need of efficient machines for harvesting, retrieval,densification, fortification, handling, transport and storage

of crop and agro-processing residues. Reliable assessment of availability of surpluses in different

regions and seasons. Efficient machines for briquetting of low density (0.40.7

gm/cm3) and high density (11.2 gm/cm3) briquettes, withand without binder.- High density, binder less briquetting/ pelleting for energypurposes 20 mm90 mm diameter for boilers, gasifiers- L ow density briquetting with and without binder for cookstoves, animal feed

Continue..Transport of crop and agro-processing residue to the

briquetting plant, in loose form is expensive. Preparation offeedstock should be done in production catchments.

Raw material cost is about 4075% of the cost of briquettesand hence availability of raw material at cheaper cost willbring down the selling cost of briquettes.

For operation of a briquetting machine of 500 kg/h capacityrunning in 2 shifts (16 h/day) and operating for about 300days/year, about 2400 tonnes of raw material will be required.

If the briquetting plant is installed in production catchmentsand collection centers are established in a cluster of fewvillages, the farmers/ landless labourers are expected to supplybiomass in small quantities, which will ensure regular supplyof different types of biomass to the briquetting plant.


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MARKET POTENTIAL OF BRIQUETTING OF CROPMARKET POTENTIAL OF BRIQUETTING OF CROPAND AGRO-PROCESSING RESIDUESAND AGRO-PROCESSING RESIDUES

Briquetting of crop residues including cotton stalks, has very goodmarket potential in India. The need is to properly harvest the crop,retrieve the crop residues, process them into proper feedstock suitablefor briquetting, transport the feedstock to the briquetting plant andprepare briquettes of different sizes for different purposes.

For operation of a briquetting machine of 500 kg/h capacity running in2 shifts (16 h/day) and operating for about 300 days/year, about 2400tonnes of raw material will be required. For one million tonnes of cropresidues, about 400 briquetting plants of 500 kg/h capacity would beneeded, operating 2 shifts per day.

For briquetting 11.8 to 13 million tonnes of surplus cotton stalk and100-125 million tonnes of total surplus crop residues about 4160 to 5200and 40,000 to 50,000 briquetting plants of 500 kg/h capacity would berequired.

Incase of cotton stalk, the entire stalk with dried leaves and branchescan be utilized for briquetting where as for making particle board orNu-wood only the hardy portion of the stalk is used.

Continue

The briquetting plants need to be installed in production catchmentsto convert the surplus biomass into value added products likedensified animal feed and good quality fuel for domestic andindustrial purposes. Will reduce environmental pollution caused dueto burning and rotting of surplus crop residues/ biomass, dry leavesand road side weeds and shrubs on one hand and felling of foresttrees for fire wood on the other hand.

One kg of briquettes can generate about 1kWh of electrical energythrough gasification route. If all the 100-125 million tonnes ofsurplus crop residues are used for power generation it has apotential of generating about 100-125 billion units of electricalenergy valued at Rs 500- 625 bill ion annually at the rate of Rs 5.00per unit.

About 11.8 million tonnes of surplus cotton stalks has a potential ofgenerating electricity worth about 59 billion Rs. annually.

About 3.5 to 4 kg of crop residue briquettes replaces one kg of LDOor diesel used for thermal application or for power generation. Thusabout 11.8-13 million tonnes of cotton stalks briquettes havepotential of replacing the requirement of L DO or diesel by about2.95 to 3.37 million tonnes annually worth Rs 10.6-12.13 bill ion, atpresent price level.

The Central and State Governments and otherorganisations li ke ICAC, CFC, progressive indust ries etc.

should give encouragement to this technology.

The above examples show that there is very good potential ofutilizing crop and agro-processing residues/ wastes for various

purposes. The need is to promote the briquetting technology ofcrop and agro-processing residues by creating awareness and

giving incentives for its promotion.

SCREW PRESS TYPE

Material is fed continuously into a screw whichforces the material into a cylindrical die, which isoften heated to 250-300C to raise the temperature tothe point where lignin starts flowing. Pressure

builds up smoothly. Briquettes are often of high quality than piston-

press unit but the power requirement per tonne ofbriquette produced is also high.

Briquettes produced by this machine have a hole inthe center which makes it burn quickly.

The wear and tear of screw is very high and requiresfrequent reconditioning.

Sl.No

Feedstock MoistureContent

%

Bulkdensity

offeedstock

kg/m3

Output ofthe

briquettingmachine

kg/h

Energy usedin

briquettingkWh/t

Truedensity ofbriquette

gm/cc

Bulkdensity ofbriquettes

kg/m3

Extent ofdensifi-cation

%

Quality ofbriquettes

1 Sawdust 10.10 240.00 618.83 43.00 1.14 615 479 Good and firm2 Sugarcane

bagasse7.57 133.00 232.72 48.77 1.10 675 827 Good and firm

3 Cotton

stalk

7.44 226.27 413.70 35.24 1.10 631.33 491 Good and firm

4 Ricestraw 7.28 50.26(Chopped

straw)112.94

(Powder)

- 39.40 1.26 -

2520

1115Good and firm

5 Wheatstraw

4.59 50.26(Chopped

straw)112.94

(Powder)

248.49 52.89 0.95 591.07 1684 asloosestraw

805 aspowder

Good and firm

6 Pearlmilletstalk

10.60 93.60(Chopped

stalk)145.47

(Powder)

295.18 46.52 0.98 538.80 1075.53 aschopped

stalk675 aspowder

Good and firm

7 Jatrophashell

9.30 287.66 619.00 38.77 1.00 684.70 348.40 Good and firm

Performance of Briquetting Machine on Different Feedstocks


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Combustion Studies of Pellets in twodifferent types of Cook Stoves

SALIENT FINDINGS OF STUDIES CONDUCTED ONSALIENT FINDINGS OF STUDIES CONDUCTED ONBRIQUETTING CROP AND AGRO PROCESSINGBRIQUETTING CROP AND AGRO PROCESSING

RESIDUES AT SPRERIRESIDUES AT SPRERI

Saw dust, sugarcane bagasse, cotton stalk, pearl millet stalk, rice straw,wheat straw, groundnut shell and jatropha shell were used in powder form

for briquetting. Good quality briquetts were obtained in all the cases. Theoutput of the machine was better in case of saw dust and jatropha shell as

compared to cotton stalk, pearl millet stalk, r ice and wheat straw.

Grinding of feedstock was done to make it in powder form for briquetting.

The cost of preparation of feedstock for briquetting was highest incase ofcotton stalk and lowest in saw dust due to the number of operations

involved.

Moisture content of feedstock had effect on true and bulk densities and

quality of briquettes. Moisture content in the range of 811% was found

better from the point output and quality of briquettes in case 7 crop residues

tried.

Cont nueCont nue The cost of briquetting (including fixed cost, feed preparation cost,

operational cost, and raw material cost) in case of sawdust, sugarcanebaggase, cotton stalk, pearl millet stalk and wheat straw were Rs. 2109, 3431,3429, 3223 and 3033 per tonne of br iquettes, respectively, when the cost wascalculated for operation of the briquetting machine in one shift. They wereRs. 1801, 2753, 3019, 2648 and 2352 per tonne of briquettes produced,respectively, when the cost was calculated on the basis of operation of themachine in two shifts. The capacity of the machine was 500 kg/h on saw dust.

Cost economic of different sizes of briquetting plants will vary. Biggercapacity plants are more economical as compared to smaller capacity plants.

The energy required in briquetting operation alone, incase of saw dust,sugarcane bagasse powder, cotton stalk powder, pearl millet powder andwheat straw powder were 41, 60, 35, 47 and 53 kwh/tonne, respectively andcost as Rs 204, 300, 177, 232.62 and 264 per tonne of briquettes produced,respectively. T he energy cost of briquetting was in the range of 5.33 to 11.04% of the total cost of briquette making for different feedstocks. The cost wil lbe lower in case of bigger capacity machines.

Good quality pellets of 22 mm and 10 mm size could be made in the pellet

press machine when the feedstock was mixed with more than 50% de-oiledcake on volume basis.

Cont nueCont nue It was safe to store briquettes than the loose biomass as the bio-degradation

of loose biomass was faster than their briquettes. The shape of the briquetteswere not changed during storage even at 90% RH .

In the process of briquetting the bulk densities of briquettes in comparisonto the respective feedstock were increased from 2.38 to 11.76 times whichwas considered advantageous from the point of view of handling, transportand storage of briquettes.

Combustion studies of briquettes and pellets, prepared from crop and agro-processing residues, showed that the briquettes prepared from the feedstockhaving less ash content could be used in gasifiers without any difficulty.Briquettes and pellets of all the seven types of feedstock studied could beused in improved metal chulha and inverted downdraft gasifier for thermalapplications.

Energetics of using crop residue briquettes for power generation showedthat about 10 to 15% of the energy which could be produced from thatresidue is utilized in bailing/transport/drying/grinding and actualbriquetting. However, for thermal application this figure will be about 5%only.

At the prevailing selling prices of briquettes between Rs. 2000-2200/tonne,the return on investment (in case of saw dust briquettes) in smaller capacitymachine was between 30-45 % and bigger machine between 75-90% when

CONCLUSIONS

An analysis of briquetting technology for convertingcrop and agro-processing residues and other biomassinto briquettes of different sizes shows that thistechnology is quite profitable and have great potential

of utilizing in future for animal feed and energypurposes. This can help in converting surplus biomassinto good quality animal feed and fuel, both fordomestic and industrial purposes. This will reduceenvironmental pollution caused due to burning androtting of surplus biomass. The Central and StateGovernments should give encouragement to thistechnology.

WHAT CAN BE BRIQUETTED

All crop and agro-processing residues, woodybiomass, saw dust from timber mills, driedleaves from orchards, shrubs and grassesalong the road sides can be used for

briquetting. The problem lies in theircollection, drying, handling and transport.Crop residues like rice and wheat straw,cotton stalks and many agro-processingresidues are not presently being briquettedand substantial quantities are being burnt inthe field for quick disposal in different partsof the country.


7/11

Crop Area

M ha

Total production ofmain products

in M t

Estimated by-productsproduced

in M t

Estimatedavailabili ty ofsurplus by-

products in M t

Cereals 121.91 212.03 401.02 80.00

Pulses 21.66 13.16 24.99 10.50Oil seeds 22.78 20.80 27.29 12.50

Cotton 9.10 10.00 (million bales) 27.30 11.80

Jute & Mesta 1.05 10.78 (million bales) 3.15 1.50

Sugarcane 4.40 300.10 84.01 60.00

Potato 1.22 24.08 1.22 --

Onion 0.45 4.79 0.45 --

Coconut 1.89 128.00 (million nuts) 7.56 5.67

Cashew nut 0.77 0.47 0.47 0.30

TOTAL 182.51 577.46 182.27

AMOUNT OF IMPORTANT CROP AND AGRO-PROCESSING RESIDUES

PRODUCED ANNUALLY AND SURPLUS AVAILABLE

Note : Area and production levels of main products are for the year 2001-02

IM PORTANT CHARA CTERI STICS OF BRIQUETT ES FOR USE AS FUEL

FOR GASIFICATION AND COMBUSTION

Biomass having higher lignin content above 12 % are good material for binder-less

briquetting.

Most of the biomass/crop residues have calori fic value in the range of about 3500-

4000 kcal/kg.

Briquettes to be used for gasification should have low ash content. Forcombustion,

briquettes even with high ash content do not pose any problem.

Good quality briquettes should have true density around 1 gm/cc.

Briquettes should be strong and should not break easily in handling and transport.

It should not absorb much water under high humidity, should not be attacked by

insects / pests and could be stored for longer duration, 3-4 years, without any

appreciable biodegradation of material.

Biomass used for briquetting should have low silica content to avoid excessive

abrasion of dies of the briquetting machine.

RESEARCH GAPS IDENTIFIED AND R&DWORK ON BRIQUETTING AT SPRERI

In the commercialIn the commercial briquettingbriquetting machines the die is heatedmachines the die is heatedto about 250-300 0c through friction or by external sourceto about 250-300 0c through friction or by external sourceof heating for raising the temperature of the biomass toof heating for raising the temperature of the biomass toabout 100-120 0c to soften the lignin.about 100-120 0c to soften the lignin.

Due to excessive friction the power requirement of theDue to excessive friction the power requirement of thebriquettingbriquetting machines are high, wear and tear of the diesmachines are high, wear and tear of the diesare fast (about 200h of work) and the densification ofare fast (about 200h of work) and the densification ofbriquettes are not uniform.briquettes are not uniform.

Crop residues like rice and wheat straw are also notCrop residues like rice and wheat straw are also notbriquettedbriquettedby these machines.by these machines.

AtAt spreri vallabh vidyanagarspreri vallabh vidyanagar, systematic r&d work is being, systematic r&d work is beingdone on the pre-heating / pre-treatment of biomass,done on the pre-heating / pre-treatment of biomass,basically with a view to reduce the power requirement ofbasically with a view to reduce the power requirement ofthethe briquettingbriquetting machines, have uniform densification ofmachines, have uniform densification of

briquettes, reduce the frequency of wear and tear of thebriquettes, reduce the frequency of wear and tear of thedies and to use low lignin and difficult crop residues likedies and to use low lignin and difficult crop residues likerice and wheat straw forrice and wheat straw for briquettingbriquetting..

OBJ ECTIVES

To generate basic data on characterization and pre-heating ofcrop residues and to standardize important characteristics ofbriquettes for use as fuel for gasification and combustion.

To generate basic data on design/operating parameters of

briquetting machines which effect energy requirement andquality of briquettes and to make necessary modifications inthe commercial machines to standardize the design.

To produce good quality briquettes of selected crop residues

which have the characteristics of fuel and are suitable forgasification and combustion and are also easy to handle,transport and store.

Conduct field evaluation of briquettes as fuel for combustionand gasification and work out cost economics and energyanalysis.

IDENTIFICATION OF CROP RESIDUES/AGRO-IDENTIFICATION OF CROP RESIDUES/AGRO-

PROCESSING RESIDUES FORPROCESSING RESIDUES FOR

DENSIFICATIONDENSIFICATION

StrawStraw : Rice and wheat in chopped form: Rice and wheat in chopped form

ShellShell : Groundnut and: Groundnut andjatrophajatrophashell in powder formshell in powder form

HuskHusk : Rice husk in powder form: Rice husk in powder form

BagasseBagasse: Sugarcane: Sugarcanebagassebagasse in powder formin powder form

Saw dust: In powder formSaw dust: In powder form

Characteristics of different crop and agro-processing residuesCharacteristics of different crop and agro-processing residuesselected for the studiesselected for the studies

Biomass L ignin

Content

%

Bulk

density

kg/m3

Calorific

value

Kcal/kg

Ash

content %

Volatile

matter %

Fixed carbon

%

STRAW

Rice 12.60 80.11 3730 15.50 68.30 16.20

Wheat 16.97 80.00 4150 8.00 77.30 14.70

SHELL

Groundnutshell

31.28 165.00 4524 3.80 73.30 22.90

Jatropha shell 11.90 106.18 3168 14.88 68.73 16.38

HUSK

Rice husk 17.20 235.00 3437 16.80 67.80 15.40

BAGASSE

Sugarcane 14.84 133.00 4216 3.00 82.00 15.00

OTHER FEEDSTOCKS

Saw dust 39.00 177.00 4463 1.60 82.90 15.50


8/11

BRIQUETTING MACHINESBRIQUETTING MACHINESCOMMERCIALLY AVAILABLE IN INDIACOMMERCIALL Y AVAILABLE IN INDIA

PISTON-RAM PRESS TYPEPISTON-RAM PRESS TYPE

Material is fed into a cylinder which is thenMaterial is fed into a cylinder which is thencompressed by a piston into a slightly tapering die.compressed by a piston into a slightly tapering die.

Diameter of briquettes is proportional to output ofDiameter of briquettes is proportional to output ofthe machine.the machine.

Commercial machines with 0.5-1.5Commercial machines with 0.5-1.5 t/ht/h capacity arecapacity areavailable. They produce briquettes in the range ofavailable. They produce briquettes in the range of50-90 mm diameter50-90 mm diameter

The power requirement of suchThe power requirement of such briquettingbriquettingmachines vary from 25 kW to 66 kW.machines vary from 25 kW to 66 kW.

SCREW PRESS TYPESCREW PRESS TYPE

Material is fed continuously into a screw whichMaterial is fed continuously into a screw whichforces the material into a cylindrical die, which isforces the material into a cylindrical die, which isoften heated to 250-300C to raise the temperatureoften heated to 250-300C to raise the temperature

to the point where lignin starts flowing. Pressureto the point where lignin starts flowing. Pressurebuilds up smoothly.builds up smoothly.

Briquettes are often of high quality than piston-Briquettes are often of high quality than piston-press unit but the power requirement perpress unit but the power requirement per tonnetonneofofbriquette produced is also high.briquette produced is also high.

Briquettes produced by this machine have a holeBriquettes produced by this machine have a holein the center which makes it burn quickly.in the center which makes it burn quickly.

The wear and tear of screw is very high andThe wear and tear of screw is very high andrequires frequent reconditioning.requires frequent reconditioning.

PELL ET PRESS TYPEPELL ET PRESS TYPE

These machines operate by extruding smallThese machines operate by extruding smalldiameter (10-30 mm) pellets through a die, whichdiameter (10-30 mm) pellets through a die, whichhas many holes.has many holes.

The extruding mechanism is often 2 or 3 eccentricThe extruding mechanism is often 2 or 3 eccentricrollers, which move inside a large cylinder orrollers, which move inside a large cylinder orconical die.conical die.

The material to beThe material to be pelletisedpelletised is fed in the cylinderis fed in the cylinderand when the rollers ride over this material andand when the rollers ride over this material androtate, they push the material through holes in therotate, they push the material through holes in thedie against resistance from pellets already formeddie against resistance from pellets already formedin the die holes.in the die holes.

Pellets are less harder than briquettes.Pellets are less harder than briquettes.Piston-ram press and pellet press type briquetting machines

Preparation of Feed Stock for BriquettingPreparation of Feed Stock for Briquetting

MOISTURE CONTENT :MOISTURE CONTENT :

Moisture content of the feed material should be betweenMoisture content of the feed material should be between

10-12 %. At this moisture content the machine runs10-12 %. At this moisture content the machine runssmoothly, the briquettes are strong and without cracks.smoothly, the briquettes are strong and without cracks.

At higher moisture content briquettes are weak andAt higher moisture content briquettes are weak andmachine operation is erratic.machine operation is erratic.

Excess steam formation also occurs which blocks theExcess steam formation also occurs which blocks theflow of incoming material. If the moisture content of theflow of incoming material. If the moisture content of thefeed stock is high, it should be dried using flash dryer orfeed stock is high, it should be dried using flash dryer orin open sun.in open sun.

If the moisture content is too low, the power requirementIf the moisture content is too low, the power requirementincreases, the output decreases and the quality ofincreases, the output decreases and the quality ofbriquettes is also not very good.briquettes is also not very good.

Following feed parameters influence the process ofbriquetting :

PARTICLE SIZE AND SHAPE :PARTICLE SIZE AND SHAPE :

In small size machines (50 mmIn small size machines (50 mm diadia briquette) for bestbriquette) for bestresults the particle size of biomass material should beresults the particle size of biomass material should be

about 6-8 mm size with 10-20% powdery component.about 6-8 mm size with 10-20% powdery component. In bigger size machines (90 mm size briquettes)In bigger size machines (90 mm size briquettes)

particle size evenparticle size even uptoupto 20-25 mm could be used.20-25 mm could be used.

Larger size particles are not conveyed throughLarger size particles are not conveyed throughproperly by the screw conveyer and startproperly by the screw conveyer and startaccumulating at entry point, resulting into jamming ofaccumulating at entry point, resulting into jamming ofthe machine and lump formation. Grinding ofthe machine and lump formation. Grinding ofmaterial to smaller sizes is necessary.material to smaller sizes is necessary.


9/11

TEMPERATURE OF BIOMASS DURING BRIQUETTING :TEMPERATURE OF BIOMASS DURING BRIQUETTING :

Briquette density, its crushing strength and moistureBriquette density, its crushing strength and moisturestability can be varied by varying the temperature ofstability can be varied by varying the temperature of

biomass.biomass. Heating of biomass makes the lignin softer therebyHeating of biomass makes the lignin softer thereby

reducing the resistance toreducing the resistance to briquettingbriquetting, results in decrease, results in decreasein specific power requirement, higher outputs, less wearin specific power requirement, higher outputs, less wearand tear of dies.and tear of dies.

In commercial machines the heat is developed due toIn commercial machines the heat is developed due tointernal and external fr iction. Lignin becomes softer at ainternal and external friction. Lignin becomes softer at atemperature of about 110c and on applying pressuretemperature of about 110c and on applying pressurehelps inhelps in binderless briquettingbinderless briquetting. The die temperature. The die temperatureshould be kept between 250-290c.should be kept between 250-290c.

Complete set of machines required forComplete set of machines required for briquettingbriquetting

1.1. Briquetting press / pellet press of desired capacity,Briquetting press / pellet press of desired capacity,complete with feed material conveying screw.complete with feed material conveying screw.

2.2. Biomass grinding unit of matching capacity withBiomass grinding unit of matching capacity withfeeding screw.feeding screw.

3.3. A dryer for drying the feed material. Normally aA dryer for drying the feed material. Normally aflash dryer is used in which hot gases upto 200-300cflash dryer is used in which hot gases upto 200-300care passed. The moisture is reduced by 10-12% justare passed. The moisture is reduced by 10-12% justin few seconds.in few seconds.

4.4. Sieve shaker for sieving the bigger size feed stocksSieve shaker for sieving the bigger size feed stocksand extraneous materials.and extraneous materials.

5.5. Storage bins or sufficient covered space for keepingStorage bins or sufficient covered space for keepingthe feed stock and briquettes produced by thethe feed stock and briquettes produced by themachine.machine.

USE OF BRIQUETTES FOR ENERGYUSE OF BRIQUETTES FOR ENERGYPURPOSESPURPOSES

Briquettes can be used in boilers,Briquettes can be used in boilers, gasifiersgasifiers, furnaces, furnacesand domestic cook stoves for thermal applications.and domestic cook stoves for thermal applications.

For domestic cook stoves 12-25 mm diameterFor domestic cook stoves 12-25 mm diameterbriquettes are more suitable.briquettes are more suitable.

For other purposes 50-60 mm size briquettes areFor other purposes 50-60 mm size briquettes arepreferred. Briquettes of 60-90 mm size are being usedpreferred. Briquettes of 60-90 mm size are being usedin big boilers andin big boilers and gasifiersgasifiers..

Producer gas obtained from briquette basedProducer gas obtained from briquette based gasifiersgasifiersafter cooling and cleaning of tar +dust can be used forafter cooling and cleaning of tar +dust can be used forrunning 100% gas operated electric generating sets.running 100% gas operated electric generating sets.

On an average 1 kg biomass briquette can produce 1On an average 1 kg biomass briquette can produce 1

kwhkwh of power.of power.

COST ECONOMICS OF BRIQUETTINGCOST ECONOMICS OF BRIQUETTINGCost comparison of two sizes ofCost comparison of two sizes ofbriquettingbriquetting plantsplants

Briquetting plant ofBriquetting plant of500 kg/h capacity500 kg/h capacity

Briquetting plant ofBriquetting plant of1500 kg/h capacity.1500 kg/h capacity.

AssumptionsAssumptions

Daily working hours in 2 shiftsDaily working hours in 2 shifts 16 h16 h 16 h16 h

Annual useAnnual use 300 days300 days 300 days300 days

Capacity utilizationCapacity utilization 80 %80 % 80%80%

Electrical power connectionElectrical power connection 45 kw45 kw 70 kw70 kw

Annual production in tonnesAnnual production in tonnes 1920 tonne1920 tonne 5760 tonnes5760 tonnes

Life of machine/shed etc.Life of machine/shed etc. 20 years20 years 20 years20 years

Cost of briquetting machine and feedstockCost of briquetting machine and feedstockgrinder including installation,grinder including installation,commissioning, electrical load, cabling,commissioning, electrical load, cabling,control panel, shed, off ice space etc.control panel, shed, off ice space etc.

Rs. 11,00,000Rs. 11,00,000 Rs. 22,00,000Rs. 22,00,000

Working capitalWorking capital Rs. 3,50,000Rs. 3,50,000 Rs. 10,00,000Rs. 10,00,000

A) annual fixed costA) annual fixed cost

i) depreciation 5%/yeari) depreciation 5%/year Rs. 55,000Rs. 55,000 Rs. 1,10,000Rs. 1,10,000

ii ) interest on capital @ 12 %ii ) interest on capital @ 12 % Rs. 66,000Rs. 66,000 Rs. 1,32,000Rs. 1,32,000

ii i) annual interest on working capitalii i) annual interest on working capital

@12%@12%

Rs. 42,000Rs. 42,000 Rs. 120,000Rs. 120,000

iv) housing 5 %iv) housing 5 % Rs. 55,000Rs. 55,000 Rs. 1,10,000Rs. 1,10,000

v) repair & maintenancev) repair & maintenance 5%5% Rs. 55,000Rs. 55,000 Rs. 1,10,000Rs. 1,10,000Cont.

vi)vi) OverheadsOverheads Wages of operators(2),Wages of operators(2),e lec t r i c ian -cum-e lec t r i c ian -cum-mechanic (1), helper/mechanic (1), helper/labourerslabourers (8) and(8) andoverheadsoverheads@@ RsRs35,000/month35,000/month

RrsRrs. 4,20,000. 4,20,000

Wages of manager(1),Wages of manager(1),operators(2),electrician-operators(2),electrician-cum-mechanic(1),helpercum-mechanic(1),helper/labourers (12) and/labourers (12) andoverheadsoverheads@ Rs 60,000/month@ Rs 60,000/month

Rrs 7,70,000Rrs 7,70,000

vii) fixed cost/tonnevii) fixed cost/tonne Rs 360.94Rs 360.94 Rs 226.04Rs 226.04

B) operating costB) operating cost

Electricity (drying, grinding +Electricity (drying, grinding +briquetting)briquetting)

60 kwh/t Rs 300/t60 kwh/t Rs 300/t 50 kwh/t Rs 250/t50 kwh/t Rs 250/t

Raw material- rs.1,000/tonneRaw material- rs.1,000/tonneWastage of raw material 5%Wastage of raw material 5%

Rs 1050/tRs 1050/t Rs 1050/tRs 1050/t

Total fixed and operating cost ofTotal fixed and operating cost ofproduction/tonneproduction/tonne

Rs 1710.98/tRs 1710.98/t Rs 1526.04/tRs 1526.04/t

Selling priceSelling price Rs 1800-2000/tRs 1800-2000/t Rs 1800-2000/tRs 1800-2000/t

Annual profitAnnual profitI)I)When selling price is Rs 1800/tWhen selling price is Rs 1800/tII)II)When selling price is Rs 1900/tWhen selling price is Rs 1900/tIII)III)When selling price is Rs 2000/tWhen selling price is Rs 2000/t

Rs 1,70,918.40Rs 1,70,918.40Rs 3,62,918.40Rs 3,62,918.40Rs 5,54,918.40Rs 5,54,918.40

Rs 15,78,009.60Rs 15,78,009.60Rs 21,54,009.60Rs 21,54,009.60Rs 27,30,009.60Rs 27,30,009.60

Return on investment (total cost ofReturn on investment (total cost ofplant and machinery +workingplant and machinery +workingcapital)capital)I) when selling price is Rs 1800/tI) when selling price is Rs 1800/tIi ) when selling price is Rs 1900/tIi ) when selling price is Rs 1900/tIi i)when selling price is Rs 2000/tIi i)when selling price is Rs 2000/t

11.78%11.78%25.03%25.03%38.27%38.27%

49.31%49.31%67.31%67.31%85.31%85.31%

The bigger size plants are more profitable. The cost of biomass is about 60-70 % of the cost of production of briquettes. Any appreciable increase in the price of biomass

will greatly influence the selling price and profitability of the whole system. The briquetting plants should be setup in the areas where feedstocks are available in plenty at reasonable prices and


10/11

BINDERLESS BRIQUETTING MACHINESCOMMERCIALLY AVAILABLE IN INDIA

PISTON-RAM PRESS TYPE

Material is fed into a cylinder which is then

compressed by a piston into a slightly tapering die. Diameter of briquettes is proportional to output of

the machine.

Commercial machines with 0.5-1.5 t/h capacity areavailable. They produce briquettes in the range of50-90 mm diameter

The power requirement of such briquettingmachines vary from 25 kW to 66 kW.

PELL ET PRESS TYPEThese machines operate by extruding small diameter

(10-30 mm) pellets through a die, which has manyholes.

The extruding mechanism is often 2 or 3 eccentricrollers, which move inside a large cylinder or conicaldie.

The material to be pelletised is fed in the cylinder andwhen the rollers ride over this material and rotate,they push the material through holes in the die againstresistance from pellets already formed in the die holes.

Pellets are less harder than briquettes.

SAW DUST SUGARCANE BAGGASE POWDER

LOOSE SUGARCANE BAGGASE GROUNDNUT SHELL POWDER

JATROPHA SHELL POWDER 50% RICE HUSK POWDER +50% SAW DUST

CHOPPED RICE STRAW CHOPPED WHEAT STRAW

Piston Press TypeBri quetting Machine

Different Types of Feedstock Used For Br iquetting

BALANCED RATIONESSENTIAL FOR MORE PRODUCTIVITY

30 to 50 % is Roughage fodder, straw, hay, silage,Brans, Cakes, meals, Grains, Chunies, any foodindustry waste etc, Molasses, Minerals

Cost of enriched straw pellets Ex works is about Rs 5 to 6per kg packed in 30 kg HDPE bags

About 3000 milch animals are served with 30 TPD

Approximately 3000 liters per day incremental milk.Value Rs 45000 per day

Straw dose ranges between 25 to 60 % in TMR

One metric ton of stored TMR Pellets can save two cows ofvalue Rs 50000 during calamity

NDDBs Experience

PERFORMANCE OF BRIQUETTING PLANT AT SPRERIOUTPUT OF THE BRIQUETTI NG MACHINE ON DIFFERENT TY PES OF FEEDSTOCK

Feed- stock Bulkdensitygm/cc

Averagemoisture content

, %

Averageoutputkg/h

Quality ofbriquettes

Density ofbriquettes,

gm/cc

Extent ofdensification

%

Saw dust 0.238 12.56(11.1514.36)

626.67 Good andfirm

1.14 479

Saw dust 0.237 8.22(8.10 8.34)

600.91 Good andfirm

1.10 464

Saw dust 0.251 28.98

(28.58 29.37)

635.25 Good and

firm*

1.12 446

Saw dust 0.237 9.53(9.39 9.67)

612.50 Good andfirm

1.12 472

B a g a s s epowder

0.133 8.22(8.10 8.34)

240-300 Good andfirm

1.10 827

Groundnutshell powder

0.264 9.39(9.02-9.76)

500* Good andfirm

1.21 458

J atropha shellpowder

0.266 11.86(11.48-12.25)

600* Good andfirm

0.97 365

C h o p p e dwheat straw

0.066 6.54(6.50- 6.58)

** Good andfirm

1.27 1924

Chopped ricestraw

0.068 13.51(13.44-13.58)

** Good andfirm

1.29 1897

Saw dust andrice huskpowder (50:50ratio)

0.278 10.25(10.32-10.18)

** Good andfirm

1.21 435

* small scale trials, ** very small scale trials, further work continuing


11/11

TOTAL ANNUAL AVAILABILITY OFAGRICULURAL WASTE

Sr.

No.

Source In Million Tonnes

1. Crop and agro-processing residues 577.46

2. Road side waste 10.74

3. Waste from Waste lands 27.12

4. Forest waste 157.18

5. Dung livestock 267.76

6. Poultry droppings 4.81

7. Fisheries waste 5.00

Total 1050.07

Out of the annual production of about 577.46 MT crop and agro-processingresidues about 100-125 MT are available as surplus.

07_srivastava

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