TEKA. COMMISSION OF MOTORIZATION AND ENERGETICS IN AGRICULTURE – 2013, Vol. 13, No. 1, 95–102

Pressure agglomeration of biomass with additive of rapeseed oil cake or calcium carbonate Aleksander Lisowski, Magdalena Dąbrowska-Salwin, Adam Świętochowski, Tomasz Motyl, Marcin Pajewski Warsaw University of Life Sciences – SGGW, 02-787 Warsaw, Nowoursynowska 166, Poland, Phone: +4822-5934527, Fax: +4822-5934514, E-mail: [email protected] Faculty of Production Engineering, Department of Agricultural and Forest Engineering, Warsaw, Poland Received February 9.2013; accepted March 14.2013

Summary. The aim of this study was to explain the effect of the 2.5% additive of calcium carbonate or 5% additive of rapeseed oil cake for chopped plant material of topinambour, prairie spartina, PXOWLÀRUDURVHSRO\JRQDFHRXVDQG9LUJLQLDPDOORZVLGD IRUGXUDELOLW\FDORUL¿FYDOXHDQGGHQVLW\RIWKHSHOOHWV7KHDGGLWLYHRI calcium carbonate and rapeseed oil cake increased the durability RISHOOHWVWRDQGUHVSHFWLYHO\DQGVOLJKWO\GHFUHDVHG WKHGHQVLW\RISHOOHWV±DQGUHVSHFWLYHO\7KHXVHRI UDSHVHHGRLOFDNHLQWKHSHOOHWVLPSURYHGWKHLUFDORUL¿FYDOXH and calcium carbonate had practically no effect on the change in this value. The most marked effect for additives was obtained IRUWRSLQDPERXUSUDLULHVSDUWLQDDQG9LUJLQLDPDOORZKRZHYHU IRUSRO\JRQDFHRXVDQGPXOWLÀRUDURVHQRVLJQL¿FDQWFKDQJHVLQ pellet durability were observed. Key words: pressure agglomeration, pellet, calcium carbonate, rapeseed oil cake, mechanical durability.

INTRODUCTION The use of alternative energy sources, including biomass, LVEHFRPLQJZLGHULQUHFHQW\HDUV>@%LRPDVVFRPEXVWLRQ technology is not complicated and thanks to the availability of cheaper raw material its use for energy purposes is more FRPSHWLWLYHWRFXUUHQWO\XVHGFRQYHQWLRQDOIXHOV>@2QH way of converting biomass is pressure agglomeration, which improves the properties of solid biofuels [4]. One of the stages in the process of pressure agglomeration is conditioning. This covers a range of activities and treatments that are designed to activate natural binders in the material [12]. During conditioning it is possible to add water or steam to the material in order to soften the ¿EHURIGHQVL¿FDWHGSDUWLFOHV>@DQGSDUWLFXODUO\WKH lignin and hemicellulose, which improves the pelletisation process and results in more durability and better physical SURSHUWLHVRIWKHREWDLQHGSHOOHWV>@,QDGGLWLRQ FRQGLWLRQLQJDOVRLQYROYHVDGGLQJVSHFL¿FELQGLQJDJHQWV or other additives.

$OWKRXJKSURGXFLQJSHOOHWVZLWKRXWDQ\DGGLWLYHVLV common [21], there has appeared an interesting possibility WRORRNIRUDPRUHHI¿FLHQWPHWKRGRIGHQVL¿FDWLRQRIDJglomerates improved with appropriately selected binders. Substances that increase pellet consistency are binders, which means that they support the pressure agglomeration process and, at the same time, they improve their quality DQGHQYLURQPHQWDOSHUIRUPDQFH>@7KH\ELQGWKHSODQW material in a sustainable product that meets standards and GRHVQRWVLJQL¿FDQWO\LQFUHDVHWKHSURGXFWLRQFRVWRIWKH DJJORPHUDWHLQFOXGLQJSHOOHWV>@$OVRELQGHUVRIIHUWKH possibility of developing a new technology and obtaining VLJQL¿FDQWO\EHWWHUDJJORPHUDWHSURSHUWLHVH[WUDGU\SURRI against the absorption of moisture from the air, with reduced energy consumption) than before , which may not only affect the combustion process itself, but to a large extent reduce emissions of SO2, N2O5, dust, CO2, etc. [8]. $GGLWLYHVERWKOLTXLGDQGVROLGSURGXFHVWURQJELQGLQJVEHWZHHQPROHFXOHVLQWKHGHQVL¿FDWHGPDWHULDO$Gditives are often used in order to improve the quality of SHOOHWVDFFRUGLQJWRFXUUHQWVWDQGDUGV>@'LIIHUHQWW\SHV of additives are used: binders that improve bindings between particles and those that reduce energy intensity of pellets and improve their combustible properties. There is also an interesting possibility to use waste substances from agricultural production as additives for the production of pellets [15]. In addition to utilising these additives, it can be assumed that rational dosing of those substances can improve physical and chemical parameters of the obtained JUDQXOHV>@ $GGLQJLQHUWPDWHULDOVIRUH[DPSOHFDOFLXPFRPSRXQGV (calcium hydroxide, calcium carbonate) improves plasticity of organic substance which is to undergo pelleting and PDNHVLWHDVLHUWRJHWIRUPV>@DQGDVPDOODGGLWLYHRI VXFKDPDWHULDORIWHQVLJQL¿FDQWO\UHGXFHVGXVW,QWXUQ on the basis of agricultural practice, it can be concluded that increasing the participation of protein improves pellet

$/(.6$1'(5/,62:6.,0$*'$/(1$'Ą%52:6.$6$/:,1



GXUDELOLW\ZKLOHDWRRKLJKSURSRUWLRQRIIDWVVLJQL¿FDQWO\ worsens it, but positively affects granulate energy [5, 18, 22]. For example, calcium carbonate increases ash melting point and thus reduces the risk of ash pollution on grades >@%HFDXVHLWLVDPLQHUDOWKHTXDQWLW\RIDVKLQFUHDVHV Such additive absorbs heat to decompose, at the same time decreasing the temperature of combustion, which in consequence leads to a reduction in the amount of NOx. The process of pelletization leads, however, to binding of the water contained in plant material. With little moisture of organic substance, the durability of bond between particles is lower, which results in the reduction of mechanical durability of pellets. In order to compensate for these defects ELQGHUVWKDWLQFUHDVHVWKHGXUDELOLW\RIELQGLQJVDQGFDORUL¿F value, eg. rapeseed oil cake, should be used in the mixtures. The aim of the study was to determine the impact of the additive of calcium carbonate and rapeseed oil cake into energy plants shredded material on the physical properties of pellets produced from these mixtures in the pressure agglomeration process.

Tests were carried out for each of the plants without the binder and with 2.5% of calcium carbonate or 5% of UDSHVHHGRLOFDNH7KHWRWDO¿QDOZHLJKWRIHDFKVDPSOHZDV NJ$IWHUHDFKWULDOWKHPDWHULDOZDVFRROHGWRDPELHQW temperature. 0HFKDQLFDOGXUDELOLW\FRHI¿FLHQWRISHOOHWVZDVGHWHUmined at a stand made in accordance with the requirements RIWKH31(16WDQGDUG'XULQJWKHWHVWVWKHELQ URWDWLRQDOVSHHGZDVUSPāPLQ–1DQGWHVWWLPH±ZDV PLQ$IWHUWKHGXUDELOLW\WHVWWKHPDWHULDOZDVVLHYHGWKURXJK DVLHYHZLWKDKROHGLDPHWHURIPPDQGWKHREWDLQHG IUDFWLRQVZHUHZHLJKHGZLWKDQDFFXUDF\RIJZKLOH durability was calculated according to the formula:

< 

P SW PS

,,

(1)

where: Ȍ±GXUDELOLW\FRHI¿FLHQW mp – pellet mass before trial, g, mpt – pellet mass after trial, g. Combustion heat was determined by the calorimetric PHWKRGXVLQJ./FDORULPHWHUDQGWKHFDORUL¿FYDOXHZDV 0$7(5,$/$1'0(7+2'6 FDOFXODWHG0LOOHGVDPSOHVRIJZHUHEXUQHGDWDSUHVVXUH RI03D7DNLQJLQWRDFFRXQWWKHK\GURJHQFRQWHQWLQWKH 7KHUHVHDUFKPDWHULDOZDVREWDLQHGIURPURVHPXOWLÀR- PDWHULDOZKLFKZDVHVWDEOLVKHGLQWKH$QDO\WLFDO&HQWHURI ra (5RVDPXOWLÀRUD), prairie spartina (Spartina pectinata), :DUVDZ8QLYHUVLW\RI/LIH6FLHQFHVWKHFDORUL¿FYDOXHZDV topinambour (Helianthus tuberosus 9LUJLQLDPDOORZ±VLGD calculated using the following formula: (Sida hermaphrodita) and polygonaceous (Polygonum sa:X :W  :Z  + , chalinense) plantations. The raw material moisture content (2) (wet basis) was determined using the dry-and-weighing PHWKRGDFFRUGLQJWR31(16WDQGDUGZLWK where: DFFXUDF\)LJ  Wu ±FDORUL¿FYDOXH0-āNJ–1, The plant material was broken up on a stationary stand Wt±FRPEXVWLRQKHDWRIVDPSOH0-āNJ–1, by means of a forage harvester and then it underwent pres- Ww – relative moisture of fuel, VXUHDJJORPHUDWLRQRQWKHSHOOHWPDFKLQH=/63%ZKRVH H – relative proportion of hydrogen in fuel. basic parameters are summarized in Table 1. Pellet density measurement was made on a randomO\VHOHFWHGUHSUHVHQWDWLYHVDPSOHRISHOOHWVIURPHDFK Ta b l e 1 . 7HFKQLFDOSDUDPHWHUVRIWKHSHOOHWPDFKLQH=/- group. Two series of measurements were performed within 63% 1 minute after the agglomeration process as well as after 15 minutes. Pellet diameter was measured in two perpenDie (I¿Power Weight Dimensions GLFXODUSODQHVLQWKHPLGGOHRIWKHSHOOHWOHQJWK/LQHDU ciency ඗ die ඗ hole hole length measurements were made by means of an electronic digital –1 >NJāK ] [kW] [kg] [mm] [mm] [mm] [mm] FDOLSHUZLWKDQDFFXUDF\RIPPWKHPHDVXUHPHQWRI    8 ± 7,5  mass of each pellet was carried out with an accuracy of 

 7,52

moisture [%]

8







7  5 4  2 1  topinambour

polygonaceous

Fig. 1. 0RLVWXUHFRQWHQWRIWKHPDWHULDOGXULQJWKHWHVWV

spartina

sida

rose

35(6685($**/20(5$7,212)%,20$66:,7+$'',7,9(2)5$3(6(('2,/&$.( JRQODERUDWRU\VFDOHV5$':$*:36&DQG the density of the pellets was determined by the formula:



5(68/76$1'',6&866,21

With additives, pellets of similar size and shape changed their colors and appearance (Table 2). Pellets produced with the additive of calcium carbonate were characterized by a slightly cracked outer surface and were matte, rough, withwhere: ȡ±SHOOHWGHQVLW\NJāP–3, out the characteristic glassy surface which is formed as a rem – pellet mass , kg, sult of thermal conversion of lignin. Pellets with rapeseed oil V – pellet volume , m3. cake were characterized by a darker color and a shiny outer Data analysis was performed using the Statistica com- surface with burnt lignin. Rapeseed oil cake reduced dust SXWHUSURJUDPYHUVLRQXVLQJWKHSURFHGXUHRIDQDO\VLV in pressure agglomeration, whereas the additive of calcium FDUERQDWHVLJQL¿FDQWO\LQFUHDVHGGXVWLQWKDWSURFHVV of variance and Duncan’s test.

U

m  9



Ta b l e 2 . Pellets after pressure agglomeration process Pellets without additive

Pellets with additive of rapeseed oil cake Pellets with additive of calcium carbonate

topinambour

polygonaceous

sida

spartina

rose

$/(.6$1'(5/,62:6.,0$*'$/(1$'Ą%52:6.$6$/:,1



$QDQDO\VLVRIYDULDQFHVKRZHGWKDWERWKWKHHQHUJ\ Ta b l e 4 . The results of the Duncan test of the analysis of mean plant species, the type of the additive, and their interaction values of the mechanical durability of pellets for homogeneous KDGDVWDWLVWLFDOO\VLJQL¿FDQWHIIHFWRQWKHSHOOHWVPHFKDQ- groups of plant species and type of additive ical durability, as in all cases, the value of the critical level Factor Ȍ Homogenous group RIVLJQL¿FDQFHRIS7DEOH 7KHUHVXOWVRIWKH Plant Duncan test (Table 4) allow the conclusion that in the case Topinambour x  of both types of additives and pellets without any additive Polygonaceous  x x three distinct homogeneous groups of pellet mechanical Sida x x 74.78 durability values were formed. Spartina x 75.45 x Rose x 88.21 Ta b l e 3 . The results of the analysis of variance of factors affecting the mechanical durability of pellets from energy plants material

Sum of Degrees of 0HDQ F p – value squares freedom square factor

Source 3ODQW$



4

  

$GGLWLYH%



2

  

Interaction: $[%



8







1.1

(UURU

54.1 

Type of additive x 

None Calcium carbonate Rapeseed oil cake

 

x x

Plant species formed four homogeneous groups, which included pairs of plant species of mixed system; this means WKDWWKHUHZHUHQRFOHDUGLIIHUHQFHVEHWZHHQWKHFRHI¿FLHQWV of mechanical durability of pellets for the investigational VSHFLHV0HDQYDOXHVRIWKHPHFKDQLFDOGXUDELOLW\WKHLU VWDQGDUGGHYLDWLRQVDQGUDQJHRIYDULDWLRQDUHVKRZQ in Table 5, a graphic interpretation of the interaction of the durability is shown in Figure 2.

 

Durability, %

85  75    topinambour

spartina

rose

polygonaceous

without additive rapeseed oil cake calcium carbonate

sida

Plant

Fig. 2. The interaction of the additive with the species of energy plants on mechanical durability of pellets

Ta b l e 5 . 7KHDYHUDJHYDOXHVRIPHFKDQLFDOGXUDELOLW\VWDQGDUGGHYLDWLRQ6'DQGFRQ¿GHQFHLQWHUYDOVIRUWKHSODQWVSHFLHV and type of additive or its lack Factor

Ȍ

6'Ȍ

Ȍ Ȍ

Population

Plant Topinambour Spartina Rose Polygonaceous Sida

 75.45 88.21  74.78

None Rapeseed oil cake Calcium carbonate

  

     $GGLWLYH   

72.87 74.74   

    

   

  

  77.51

15 15



15

35(6685($**/20(5$7,212)%,20$66:,7+$'',7,9(2)5$3(6(('2,/&$.( 5RVHSHOOHWVKDGWKHKLJKHVWGXUDELOLW\± EXW the effect of additives on the value rate change of mechanical durability was the lowest and ranged within statistical error (Fig. 2). For other plants, additives improved pellet durability more effectively. The additive of rapeseed oil cake increased durability to a greater extent than the additive of calcium carbonate (Fig. 2). The additive of calcium carbonate and rapeseed oil cake allowed to increase the GXUDELOLW\RISHOOHWVE\DQGUHVSHFWLYHO\7R sum up, the greatest effect of additives was obtained for topinambour, spartina and sida, but for rose and polygonaceous practically no change in the pellets durability was recorded. Therefore the durability of the produced pellets ZDVPDLQO\DIIHFWHGE\WKHW\SHRIGHQVL¿FDWHGPDWHULDODQG W\SHRIDGGLWLYH7KLVREVHUYDWLRQFRQ¿UPVWKHLQIHUHQFHRI 1LHG]LyáNDHWDO>@ZKRDOVRIRXQGWKDWWKHSHUFHQWDJHRI DGGLWLYHVLQSUHSDUHGPL[WXUHVKDVDVLJQL¿FDQWLQÀXHQFHRQ WKHGXUDELOLW\RISHOOHWV$QRWKHUIDFWRULQÀXHQFLQJWKHYDOXH RIGXUDELOLW\FRHI¿FLHQWLVDOVRWKHPRLVWXUHRIPDWHULDO>@ ,QRXUVWXG\PDWHULDOIURPPXOWLÀRUDURVHKDGUHODWLYHO\WKH KLJKHVWPRLVWXUH EXWWKHORZHVWPRLVWXUHIRUVLGD  ZDVQRWORZHUVLJQL¿FDQWO\HQRXJKLQWKLVDUHDWR draw any conclusions about its impact on the durability of pellets, especially since the moisture content of the material was covariate and was associated with plant species. 3HOOHWFDORUL¿FYDOXHVUDQJHGIURP0-āNJ–1 for poO\JRQDFHRXVZLWKRXWDQDGGLWLYHWR0-āNJ–1 for spartina

ZLWKRXWDQDGGLWLYH)LJ )RURWKHUSODQWVFDORUL¿FYDOXHV ZHUHVLPLODUDQGZHUHDSSUR[LPDWHO\0-āNJ–1. Calcium FDUERQDWHKDGQRVLJQL¿FDQWHIIHFWRQWKHFDORUL¿FYDOXHRI pellets and the additive of rapeseed oil cake generally caused DLQFUHDVHLQFRPEXVWLRQKHDWDQGFDORUL¿FYDOXH $QDQDO\VLVRIYDULDQFHVKRZHGWKDWSHOOHWGHQVLW\RIZDV DIIHFWHGLQDVWDWLVWLFDOO\VLJQL¿FDQWZD\E\WKHPDLQIDFWRUV species of energy plants, the type of the additive used, the time of measurement and all of their double and triple interDFWLRQVZLWKDFULWLFDOVLJQL¿FDQFHOHYHOS7DEOH  On the basis of an analysis of the Duncan test (Table 7) four KRPRJHQHRXVJURXSVIRUWKHSODQWVSHFLHVZHUHLGHQWL¿HG LQFOXGLQJDFRPPRQJURXSFUHDWHGE\VSDUWLQDDQGURVH$Q DGGLWLYHRIFDOFLXPFDUERQDWHGLGQRWVLJQL¿FDQWO\GLIIHUHQtiate the density of pellets because it formed homogenous groups with the additive of rapeseed oil cake and without any additive. Table 7 summarizes the mean density of the pellets determined after 1 min and after 15 min from the time of pellet production for comparison purposes only, because IRUWZRIDFWRUOHYHOVYDULDQFHDQDO\VLVUHVXOWVDUHVXI¿FLHQW 7DEOH $VPDOOHUYDOXHRIIRUGHQVLW\RIWKHSHOOHWV after 15 min indicates the expansion of the pellets associated with stress relaxation of the material between the particles GXULQJWKHLUVWRUDJH$YHUDJHGHQVLWLHVRISHOOHWVZLWKWKHLU VWDQGDUGGHYLDWLRQVDQGUDQJHRIYDULDWLRQDUHVKRZQLQ Table 8, and the graphic interpretation of factors interaction on the density of pellets is presented in Figure 4.

 without additive calcium carbonate rapeseed oil cake

-1

&DORULILFYDOXH>0-āNJ ]



12

8

4

 topinambour

polygonaceous

sida

spartina

rose

Fig. 3. &DORUL¿FYDOXHVRISHOOHWV Ta b l e 6 . The results of the analysis of variance of factors affecting the density of the pellets from energy plants material Source

Sum of squares

3ODQW$ $GGLWLYH% Time: C ,QWHUDFWLRQ$î% ,QWHUDFWLRQ$î& ,QWHUDFWLRQ%î& ,QWHUDFWLRQ$î%î& (UURU

       

Degrees of freedom 4 2 1 8 4 2 8 



0HDQVTXDUH        

F factor    47.5  21.4 47.1

p – value       

$/(.6$1'(5/,62:6.,0$*'$/(1$'Ą%52:6.$6$/:,1



Ta b l e 7 . The results of the Duncan test of the analysis of mean values of the density of pellets for homogeneous groups of plant species, type of additive and measurement time ȡNJāP–3 Homogenous group Plant Spartina  x Rose  x Topinambour  x Polygonaceous  x Sida 1218.51 x Type of additive Rapeseed oil cake  x Calcium carbonate  x x None  x 0HDVXUHPHQWWLPHPLQ 1  x 15  x Factor

$IWHUPLQIURPWKHSHOOHWVSURGXFWLRQVLGDZLWKRXW additive was characterized by the highest density of pellets, whereas spartina with rapeseed cake had the lowest pellet GHQVLW\)LJ 7KHGHQVLW\RISHOOHWVDIWHUPLQZDV VPDOOHUEXWPRUHVWDEOHWKDQDIWHUPLQ$IWHUPLQIURP the pellet production, the additive of calcium carbonate increased the density of pellets made of spartina material and after 15 min also of the material of topinambour and VLGD*HQHUDOO\KRZHYHUWKHDGGLWLYHRIFDOFLXPFDUERQDWH and rapeseed oil cake contributed to a slight decrease in SHOOHWGHQVLW\E\DQGUHVSHFWLYHO\&RQ¿UPDWLRQ of this inference requires an extension of research on the participation of additives, extended time of stress relaxation in the pellets, increasing the moisture content and diversity of agglomerate pressure.

Ta b l e 8 . 7KHDYHUDJHYDOXHVRIGHQVLW\VWDQGDUGGHYLDWLRQ6'DQGFRQ¿GHQFHLQWHUYDOVIRUWKHSODQWVSHFLHVW\SHRI additive or its lack and measurement time Factor

ȡNJāP–3

6'ȡNJāP–3

ȡNJāP–3 Plant      $GGLWLYH    Time  

ȡNJāP–3

Population

Topinambour Spartina Rose Polygonaceous Sida

    1218.51

7.14 7.14 7.14 7.14 7.14

    

    

None Rapeseed oil cake Calcium carbonate

  

  

  

  

1 15

 

4.51 4.51

 

 

1400 1350 1300

Density, kg•m-3

1250 1200 1150 1100 1050 1000 950

Time, min: 1

Time, min: 15

sida

polygonaceous

rose

spartina

topinambour

sida

rose

spartina

topinambour

850

polygonaceous

900

without additiv e rapiseed oil cake calcium carbonate

Fig. 4. The interaction of the additive with the species of energy plants and measurement time on the density of pellets

35(6685($**/20(5$7,212)%,20$66:,7+$'',7,9(2)5$3(6(('2,/&$.(  &21&/86,216 1. The additive of calcium carbonate or rapeseed oil cake allowed to increase mechanical durability of pellets by DQGUHVSHFWLYHO\DQGVOLJKWO\GHFUHDVHG SHOOHWGHQVLW\E\DQGUHVSHFWLYHO\$OVRWKH FDORUL¿FYDOXHRIWKLVVROLGIXHOFKDQJHGVOLJKWO\ 2. The density of the pellets after 15 minutes was smallHUE\EXWPRUHVWDEOHWKDQDIWHUPLQXWHIURP production time, which indicates that expansion of the pellets is associated with stress relaxation between the particles of the material during their storage time.  7KHPRVWPDUNHGHIIHFWRIXVLQJDGGLWLYHVZDVREtained for topinambour, spartina and sida, but for rose and polygonaceous practically no change in the pellets durability was recorded. However, pellets from rose were characterized by the highest values of the meFKDQLFDOGXUDELOLW\FRHI¿FLHQW± ZKLFKPD\ be due to the structure and physical properties of that material. 4. Pellets produced with the additive of calcium carbonate were characterized by a slightly cracked outer surface and were matte, rough, without the characteristic glassy surface, formed as a result of thermal conversion of lignin. Pellets with an additive of rapeseed oil cake were characterized by a darker color and a shiny outer surface with burnt lignin. 5()(5(1&(6 1. Borowski G., Kuczmaszewski J. 2005: Utilization RIWKH¿QHJUDLQHGPHWDOZDVWHV0RQRJUDSKHG3ROLWHFK/XEHOVND/XEOLQ,6%1LQ Polish) 2. Fiszer A., Dworecki Z. 2012: Durability test for comPRQUHHGSHOOHWV-5HV$SSO$JU(QJ ± (in Polish)  )UąF]HN-%LRPDVVSURGXFWLRQIRUHQHUJHWLFSXUSRVHVHG37,5&UDFRZ,6%1LQ Polish) 4. *ROXEHQNR$7V\YHQNRYD10XO\DU25RPDQXVKun O. 2011: %LRPDVVVWDQGDUGL]DWLRQDVDEDVHIRULWV VXI¿FLHQWXVHɌȿ.Ⱥ.RP0RWL(QHUJ5ROQ±2/ 3$1$± 5. Grochowicz J. 1998: $GYDQFHGPDQXIDFWXULQJWHFKQLTXHVRILQGXVWULDOIHHGFRPSRXQGHG3$*526VF /XEOLQ,6%1LQ3ROLVK  Gubacheva L., Andreev A., Shevchenko D. 2011:$OWHUQDWLYHIXHOVIRUWUDQVSRUWɌȿ.Ⱥ.RP0RWL(QHUJ 5ROQ±2/3$1$± 7. Hartmann H., Turowski P., Robmann P., Ellner-SchuEHUWK)+RSI1*UDLQDQGVWUDZFRPEXVWLRQ LQGRPHVWLFIXUQDFHV±LQÀXHQFHVRIIXHOW\SHVDQGIXHO SUHWUHDWPHQWV>,Q@3URFHHGLQJVRIWKHWK(XURSHDQ %LRPDVV&RQIHUHQFHDQG([KLELWLRQ%HUOLQ 8. Hejft R. 2002: Pressure agglomeration of plant materials. HG3ROLWHFK%LDáRVWRFND%LDO\VWRN,6%1 (in Polish)

 Hess R., Kenney K., Wright C. 2010: $ WHFKQLFDO UHYLHZ RQ ELRPDVV SURFHVVLQJ GHQVL¿FDWLRQ SUHSURFHVVLQJPRGHOLQJDQGRSWLPL]DWLRQ±>DFFHVV @$YDLODEOHLQWKH,QWHUQHWKWWSZZZLQO JRYWHFKQLFDOSXEOLFDWLRQVGRFXPHQWVSGI .DOL\DQ10RUH\5Natural binders and solid bridge type binding mechanisms in briquettes and pelOHWVPDGHIURPFRUQVWRYHUDQGVZLWFKJUDVV%LRUHVRXU 7HFKQRO± 11. Kowalik P. 2002: Perspectives of biomass pelletizing LQ3RODQG&]\VWD(QHUJLD±LQ3ROLVK 12. Kulig R. 2007: (IIHFWVRIFRQGLWLRQLQJPHWKRGVRQHQHUJ\FRQVXPSWLRQGXULQJSHOOHWLQJ7(.$.RP0RW (QHUJ5ROQ±2/3$1$± Kulig R., Laskowski J. 2008a:(IIHFWRIFRQGLWLRQLQJ parameters on pellet temperature and energy consumpWLRQLQWKHSURFHVVRISODQWPDWHULDOSUHVVLQJ7(.$ .RP0RW(QHUJ5ROQ±2/3$1D± 14. Kulig R., Laskowski J. 2008b:(QHUJ\UHTXLUHPHQWVIRU pelleting of chosen feed materials with relation to the PDWHULDOFRDUVHQHVV7(.$.RP0RW(QHUJ5ROQ ± 15. Mani S., Tabil L.G., Sokhansanj S. 2006: (IIHFWVRI compressive force, particle size and moisture content on mechanical properties of biomass pellets from grasses. %LRPDVV %LRHQHUJ\± 1LHG]LyáND,6]SU\QJLHO0$VVHVVPHQWRITXDOLW\SURSHUWLHVRISODQWELRPDVVSHOOHWV,QĪ5RO  ±LQ3ROLVK 17. 1LHG]LyáND , 6]\PDQHN 0 =XFKQLDU]$ =DZLĞODN.Characteristics of pellets produced from VHOHFWHGSODQWPL[HV7(.$.RP0RW(QHUJ5ROQ ±2/3$1± 18. 1LNRODLVHQ/1¡UJDDUG-HQVHQ7+MXOHU.%XVN- Junker H., Sander B., Baxter L., Bloch L. 2002: QualiW\FKDUDFWHULVWLFVRIELRIXHOSHOOHWV$DUKXV'DQLVK7HFKQRORJLFDO,QVWLWXWHDSS Sedlácek P., Martinek T., Fecko P. 2003: (FRORJLFDO SHOOHWVIURPEURZQFRDODQGELRPDVV,QĪ\QLHULD0LQeralna, 4(2), 11–17. (in Polish) Skoch E., Behnke K., Deyoe C., Binder S. 1981: The effect of steam-conditioning rate on the pelleting proFHVV$QLP)HHG6FL7HFK± 21. Sokhansanj S., Mani S., Bi X., Zaini P., Tabil L. 2005: %LQGHUOHVVSHOOHWL]DWLRQRIELRPDVV$6$(3DSHU1R 6W-RVHSK0LFK$6$( 22. =DZLĞODN.*URFKRZLF]-6REF]DN3The analysis of mixing degree of granular products with the XVHRIPLFURWUDFHUV7(.$.RP0RWL(QHUJ5ROQ± 2/3$1F± $*/20(5$&-$&,ĝ1,(1,2:$%,20$6