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Compaction behaviour of cotton stalks grinds.

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Misr J. Ag. Eng., January 2005 191

COMPACTION BEHAVIOUR OF COTTON STALKS GRINDS

1M. M. Ibrahim

2 S. M. Younis

3 A.Z. Taieb

4 B. S. Azzam

ABSTRACT

The compaction behaviour of biomass grinds such as cotton stalks was investigated

at different applied forces, water contents, and particle sizes using a single pelleter

tester setup. A fixed amount of material (70 g) was compressed in a 63-mm

diameter closed-end cylindrical die using a computerized hydraulic press. Data

was employed for the collection of instantaneous readings of load and material

deformation from control head of the press. Three compaction parameters were

incorporated in this study, namely; the compressing load, material (grinds) water

content and the grinds particle size. The influences of these parameters and

compaction process, and or on the compacted products, were investigated for

cotton stalks grinds throughout this study. The results showed that densities

attained under the different parameters used in this study ranged from 958 to 1180

kg/m 3

. The particle size differ from 3-mm to 1.4-mm the material is categorized as

very compressible. Nevertheless, with particle size, change from the 1.4-mm to 0.7-

mm the material is categorized as less compressible. The compaction energy

required is a strong function of pressure and covered a range from about 3.2 and

6.4 MPa (the energy ranged from 7.79 -16.76 kJ/kg or MJ/ton residue) with different

water contents and particle sizes of the material to save the energy. This amount of

energy was a small fraction about (0.047% - 0.01 %) of cotton stalks energy

content. These findings stress the importance of optimizing cotton stalks

compaction if efficient compaction equipment and processes are to be secured.

Keywords. Cotton Stalks, Densification, Stress, Briquettes, Compaction energy,

Density.

INTRODUCTION

Many of the developing countries produce huge quantities of agro residues but they

used it inefficiently causing extensive pollution to the environment. Agricultural

crop residues are a valuable resource for which to produce biobased products.

Apart from the problems of transportation, storage, and handling, the direct burning

of loose biomass in conventional grates is associated with very low thermal

efficiency and widespread air pollution (USDA NASS,2001).

In Egypt, large amounts of cotton stalks are produced annually and impose disposal

and environmental problems. Therefore, this study comes as an attempt to utilize

cotton stalks by realizing the benefits of biomass densification for energy.

1 Assistant lecturer, Ag. Eng. Dept., Fac. of Agr., Cairo Univ. 2 Prof. of Agr. Eng., Fac. of Agr., Cairo Univ. 3 Assoc. Prof. of Agr. Eng., Fac. of Agr., Cairo Univ. 4 Assoc. Prof. of Mech. Design and Prod., Fac. of Eng., Cairo Univ.

Misr J. Ag. Eng., 22 (1): 191 - 206

Misr J. Ag. Eng., January 2005 192

Conversion of low bulk density biomass into a densified form for energy

conversion improves handling, transportation and storage. Therefore, effective

handling and transportation of bulky biomass can be possible by transforming them

into a denser and durable form. So, studying the compaction behaviour of these

materials becomes more important in achieving this goal. The quality and strength

of the densified mass depends on the physical properties of the material, applied

forces and other compaction process variables.

In order to design machinery such as extruders, pelletizers, cubers and briquetters

used to compact biological materials such as fibrous agricultural residues, it is

necessary to have some knowledge about the mechanical behaviour of such

materials at all stages of their process. The mechanical and physical properties of

there compaction parameter depend on the applied stress, strain, moisture content

and temperature.

The goal of this work was to investigate the densification characteristics of cotton

stalks as expressed by the stress-density behaviour of cotton stalks under pressure

and the energy required for material compaction. These two aspects are critical to

the design of efficient compaction equipment and the process feasibility. The

objectives of this study were:

To examine gains in material density after compaction relative to the loose

material,

To present the material stress-density relationship, and

To evaluate the feasibility of material compaction from the energy

requirement of the process.

El-Raie et al. (1996) investigated the characteristics of fuel values of some

agricultural residues such as barley straw, fababean seed coat, dry sugar cane

leaves, rice straw, corn cobs, cotton stalks, corn husks, corn stalks, and wheat straw

converted into energy from them as alternative energy source.

El-Berry et al. (2001) mentioned that the quantity of crop residues in Egypt

reached about 18.6-25 million-ton per year and the national income might be

increased with 1.6 billion L.E / year if it is recycled. On the other side, El-Khateeb

(2001) reported that in Egypt there are about 15 million-tons/ year of the field raw

materials as vegetative residues of corn, corn stalks and rice straw and they are

currently used as a fuel. Roof-top storage of cotton, corn stalk and rice straw

bundles presents a serious fire hazard. And also, it offers a dwelling environment

for control boll worms.

Gomaa et al. (1997) mentioned that burning of cotton stalks of quantity about 1.24

million ton (dry matter)/year means a great loss of energy equivalent to 0.583

million T.O.E./year (Tone Oil Equivalent =11.63 MWH) valued 180 million

L.E/year. Also mentioned that heat calorific value for cotton stalks is 3938 kCal/kg

so it can be useful for using it as a fuel.

Misr J. Ag. Eng., January 2005 193

Biomass densification means the use of some form of mechanical actuator to

compeer the grinds and so reduce their volume by transforming them into a solid

form, which is easier to handle and store than the original material (Ericksson and

Prior 1990).

The process of compaction of residues into a product of higher bulk density than

the original raw material is known as densification. Densification has aroused a

great deal of interest in developing countries all over the world in recent years as a

technique of beneficiation of residues for utilization as energy source

(Bhattacharya, 2001).

Densification of biomass is one of the important processes for effective handling

and storage of bulky biomass materials. Biomass such as straws, corn Stover can be

utilized for making pellets and for production of ethanol. Biomass residues have

low bulk densities and thus, low volumetric heating values. Thus, handling and

storage are major obstacles in bio-based energy production. The bulk density of

loose straw and bagasse is around 40 kg/m³; the highest bulk density of un-

processed biomass is about 250 kg/m³ for some wood residues (Demirbas 2001).

Briquetting or pelletizing is another term for densification or compaction, i.e., the

application of pressure on a material for the following purposes (Olorunnisola

2000):

o Reduce the bulk, i.e., increase the density of the material, to make

transportation easier and cheaper.

o Increase the energy content per unit volume of the material by reducing the

moisture content during the compaction process.

o Obtain a homogeneous product, having the same physical characteristics

(density, particle size and moisture content) from a highly heterogeneous

group of materials.

o Maintain uniform quantity of energy per unit feedstock.

o Obtain a highly cohesive fuel product from particulate materials that are

otherwise difficult to process.

o Increase resistance to breakdown of particles in shipping, handling and

storage.

Miguel and Guillermo )2002( reported that for densification of biomass, it is

important to know the feed parameters that influence the extrusion process were

moisture content, temperature, compaction pressure and size of particles, these are

the required parameters of raw materials.

Jenike (1961) have proposed a compressibility constant as a measure of powder

compressibility. A powder sample is compressed in a shear cell ring and

displacement recorded. The results are represented on a logarithmic plot and a

straight line fitted through the points. The compressibility constant is

determined by:

Misr J. Ag. Eng., January 2005 194

1

0

1 0

1

0 1 0

Log Log

0

1

1 0

Log

Log

(1)

Where:

: Compressibility constant

: Bulk density at consolidating stress 1 or load

0 : Bulk density at initial consolidating stress 1 0 or initial load

The slope of line is a measure of the compressibility of bulk solids and varies

between 1.0 for very hard compressible materials to close to zero for very

compressible materials.

The energy required for material compaction is a basic aspect of biomass

densification. This aspect is essential in judging whether material compression is

feasible under given conditions. The energy, E, required for material compaction

may be determined from the expression (Bhattacharya et al., 1989):

E Fdy (2)

Where:

F : the applied axial force (load) and

y : the material deformation.

MATERIAL AND METHODS

- Material preparation: Cotton stalks were obtained from the farm of the Faculty of Agriculture at Cairo

University. The physical properties of the stalks as shown in table (1). The hammer

mill (WILEY CUTTING MILL) used for grinding materials. Hammer mills crush

the stalks into small particles due to the shear and impaction action. The hammer

mill used in this study consisted of 8 hammers, attached to a shaft powered by a 0.4

kW DC-electric motor. The shaft rotated at a speed of 990 rpm. The material was

crushed or shattered by the repeated hammer impacts, collisions with the walls of

the grinding chamber, as well as particle–on–particle impacts. Perforated metal

screens covering the discharge opening of the mill retained coarse materials for

further grinding while allowing the properly sized materials to pass as finished

products.

Misr J. Ag. Eng., January 2005 195

Table (1): Physical properties of cotton stalks.

Residue

Stem diameter

(mm) Stem length

(mm)

Water

content

(d.b.), %

Bulk

density,

,(kg/m3)

Bottom Top

Cotton stalks 8-16 4-8 710-1850 15-20 80

- Particle Size Distribution:

A sample grind of 100 g was placed in a stack of sieves arranged from the largest

to the smallest opening sizes. The sieve series selected were based on the range of

particles in the sample. Sieve numbers were 2, 1.4 and 0.7. Sieve analysis was

repeated three times for each ground samples. The particle size was determined

according to ANSI/ASAE standard S319.3JUL97- 2001.

- Single pelleter:

Figure (1) shows a single pelleter unit, used to study the compression behavior of

biomass grinds. The pelleter unit was basically a plunger and die assembly attached

to the computerized hydraulic testing machine (AUROGRAGH) as shown in

Figure (2). The pelleter die had a diameter of 63-mm and a length of 170 mm. The

clearance between the pelleter and the cylinder was 0.2 mm.

Figure (1): Single pelleter unit.

- Compression test:

Compression test was conducted using a single pelleter unit for grinds cotton stalks

with three different particle sizes (0.7, 1.4 and 3 mm) at 6% and 15% (d.b) water

contents. Some batches were dried by spreading them exposed to the atmospheric

air for different periods and others were put in an oven to get the required water

F

Plunger

cylinder

closed end

Misr J. Ag. Eng., January 2005 196

content. A known amount of grind samples was pelleted in the single pelleter unit.

Compression of the grind was performed by a computerized hydraulic testing

machine with a vertical piston, which used for axial pressure application on the

loose material. The piston, with a clearance of 0.2 mm between piston head and die

walls, was present to allow air to escape upward during compression. The

compression loads used for the test were; 1000, 2000, 3000, 4000 and 5000 kg and

at a crosshead speed of 60 mm/min. The pellet formed was removed by gentle

tapping using a plunger. The mass, length and diameter of the pellets were

measured to establish a pressure-density relationship.

Figure (2): Photo of the computerized hydraulic testing machine.

The testing process started by weighing 70 g of the material in a beaker and

pouring it into the die. The loaded die was then placed on top of the piston. The

compression stroke began when the piston came in contact with the loose material

in the die. The stroke then proceeded as the piston slowly extended into the die

until a pre-set maximum pressure was reached, which would be held for the

specified hold time. The compacted unit was then ejected by replacing the lower

cover with the ejection cylinder and pushing the unit through by the piston. During

the compression stroke, both the piston displacement and the applied axial load

were recorded on the computer attached with the testing machine.

The density of briquettes was determined by calculating the mass-to-volume ratio

(Mohsenin and Zaske, 1976) while stress was calculated from dividing the load

cell reading (force) by the die (briquette) cross-sectional area. The stress-density

relationship of cotton stalks compaction was determined from the instantaneous

values of applied axial load (stress), briquette (die) diameter, and material

Misr J. Ag. Eng., January 2005 197

deformation during the compression stroke by the hydraulic press control. As for

compaction energy, the approach was to calculate the area under the load-

deformation curve.

RESULTS AND DISCUSSION

- Particle Size Distribution:

Particle size distribution by mass on each sieve is shown in table (2). Cotton stalks

had 45.5 % of the particles less than 0.7 mm, and 8.0 % of the particles were larger

than 2 mm (table2).

Table (2): Particle size analysis for grinding stalks.

Particle size (mm) ≤ 0.7 >0.7- 1.4 >1.4 - 2 >2- 3

Percentage of Particle size (%) 45.5 39.0 7.5 8.0

- Unit Density of Briquettes:

Density is the single most important physical characteristic of densified biomass

and in many cases provides the justification of material compaction. The term unit

density, or simply density, refers to the density of an individual briquette.

The density of the cotton stalks and grind cotton stalks were 80 and 287 kg/m3

respectively. Observations indicated that only the level of maximum stress had

affected briquette maximum density. It is the ultimate briquette density attained

under a given maximum stress in the die. It can be observed in table (3), at particle

size 3 mm. the density ranged from 958 – 1140 kg/m3 under changed load from

1000 – 5000 kg and water content 6%, 15%. These represent about 3.33 – 3.97

times of grind cotton stalks and about 11.97 – 14.25 times of cotton stalks. At

particle size 1.4 mm, the density ranged from 1070 – 1145 kg /m3 with different

load and water content. These represent about 3.73 – 3.98 times of grinds cotton

stalks, and about 13.37 – 14.31 times of cotton stalks. At particle size 0.7 mm, the

density ranged from 1080 – 1180 kg / m3 with different load and water content,

these represent about 3.76 – 4.11 times of grinds cotton stalks and about 13.5 –

14.75 times of cotton stalks. It can be observed from table (3) that with increasing

water content, the density decreases at different particle sizes (3 mm, 1.4 mm, 0.7

mm). Water content causes increasing in particle size so the volume increases thus

decrease the density. With decrease particle size from 3 mm – to 0.7 mm density

increased, because the volume decreases.

It is well known that to obtain fine to particles, it consumes more energy. In order

to save energy, it is recommended to deal with particle size 3 mm instead of 1.4

mm or 0.7 mm. Because, Particle size 3mm represents 3.33 – 3.97 times of grind

cotton stalks and about 11.97 – 14.25 times of cotton stalks while particle size 1.4

mm and 0.7 mm represent 3.73 – 3.98 and 3.76 – 4.11 times of grind cotton stalks,

also represent about 13.37 – 14.31 and 13.5 – 14.75 times of cotton stalks,

respectively. The differences between 3 mm and (1.4-0.7) mm are not observed.

Misr J. Ag. Eng., January 2005 198

Table (3): The density (kg/m3) and energy required (kJ/kg) for the grinds

cotton stalks at different loads, water contents and particle sizes of material.

Load (kg) Pressing pressure

(MPa)

Size 3mm

Water content

6% 15%

Density Energy Density Energy

1000 3.2 979 7.86 958 7.79

2000 6.4 1090 16.40 1040 16.11

3000 9.6 1108 24.74 1048 24.24

4000 12.8 1126 33.17 1051 32.36

5000 16.0 1140 41.64 1052 40.46

Load (kg) Pressing pressure

(MPa)

Size 1.4 mm

Water content

6% 15%

Density Energy Density Energy

1000 3.2 1095 8.21 1070 8.14

2000 6.4 1110 16.50 1085 16.37

3000 9.6 1125 24.87 1095 24.64

4000 12.8 1140 33.31 1119 33.10

5000 16.0 1145 41.70 1122 41.41

Load (kg) Pressing pressure

(MPa)

Size 0.7 mm

Water content

6% 15%

Density Energy Density Energy

1000 3.2 1098 8.22 1080 8.17

2000 6.4 1162 16.76 1158 16.74

3000 9.6 1172 25.21 1165 25.16

4000 12.8 1177 33.66 1170 33.60

5000 16.0 1180 42.11 1178 42.09

- Stress-Density Relationship:

Figure (3) shows that the material deformed at a constant rate through load varies

from zero to1000 kg. After that deformation rate decreased and material

deformation reached its ultimate value. In figure (4) shows the density behaves the

same trend.

A typical stress-density curve is shown in figure (4), which is intended to show the

general trend only. Clearly, the instantaneous values of both stress and density will

vary for different levels of pressure and water content.

Misr J. Ag. Eng., January 2005 199

0

10

20

30

40

50

60

70

0 1000 2000 3000 4000 5000

Load (kg)

Defo

rmati

on

(m

m)

Figure (3): Variation of load with material deformation in the during

compression.

900

950

1000

1050

1100

1150

1200

3 6 10 13 16

Pressure(MPa)

De

ns

ity

(k

g/c

m3)

6% (3 mm) 15% (3 mm)

6% (1.4 mm) 15% (1.4 mm)

6% (0.7 mm) 15% (0.7 mm)

Figure (4): Relationships between the bulk density and vertical pressure

determined for cotton stalks during compression in a closed-end die.

A close look at figures (3), (4) show that there are three distinct regions:

Initial stage of compression: The material showed only small resistance and

behaved like a highly compressible material and, thus, large particles in density

were realized by small increases in stress. It may be theorized here that the load had

to bring material particles closer together by merely reducing pore space by forcing

air out of material voids.

Misr J. Ag. Eng., January 2005 200

Middle stage of compression: As the piston advanced into the die the material

showed gradual increases in stress, which may be attributed to the higher stress

needed to cause the mechanical changes in material particles including bending and

crushing.

Final stage of compression: Toward the end of the compression stroke and after

the material had attained a certain density, stress increased sharply for negligibly

small density changes indicating a behaviour similar to that of an incompressible

material. At this point the material was compressed as much as was apparently

possible.

-Compressibility:

The compressibility behaviour was determined empirically by plotting the

experimental data (Load-density) and then applying curve fitting to those data

using a spreadsheet (Excel). For all cases of this study, the best fit (linear

regression) to the data had the following analytical form as shown in figure (5).

The compressibility constant ( ) is a number has under line in the equation that

resulted from the curve fitting.

y = 0.0439x + 2.9134

R2 = 0.8651

y = 0.0515x + 2.8846

R2 = 0.851

y = 0.0288x + 2.9518

R2 = 0.9751

y = 0.0918x + 2.7226

R2 = 0.918

y = 0.0308x + 2.9355

R2 = 0.9312

y = 0.0568x + 2.8186

R2 = 0.8015

3.0

3.0

3.0

3.0

3.0

3.1

3.1

2.5 3 3.5 4

Log consolidating load, (kg)

Lo

g b

ulk

de

ns

ity

,(k

g/m

3)

3 mm 6%

3 mm 15%

1.4 mm 6%

1.4 mm 15%

0.7 mm 6%

0.7 mm 15%

Figure (5): Determination of compressibility constant at different water

contents and particle sizes.

As mentioned before, the slope of line is a measure of the compressibility

constant of bulk solids and varies between 1.0 for very hard compressible materials

to close to zero for very compressible materials.

Figure(5) shows that with particle size 3-mm for material increasing water content

from 6% to 15 % the decreased from 0.0918 to 0.0568 which means that the

material will be more compressible with increasing water content. With particle

size 1.4-mm and 0.7-mm with increasing water content from 6% to 15% increased from (0.0288 to 0.0308) and (0.0439 to 0.0515) respectively.

Misr J. Ag. Eng., January 2005 201

It is observed that when the particle size was reduced from 3-mm to 1.4-mm

decreased that meaning that material will be very compressible, due to the fineness

of material and gained sensitivity to compression. However, as particle size

changes from the 1.4-mm to 0.7-mm increased meaning that material will be

less compressible as it is fine enough to the particle with 0.7-mm was very fine,

there for the material needs very high load to provide noticeable compressibility.

- Energy Requirement:

The experimental data of load-deformation can be utilized to calculate the energy

required for the compaction of one briquette. Specific energy is the compaction

energy expressed per unit mass of material and is obtained by knowing the

briquette mass.

From the data of this study, it was found that the specific compaction energy for

cotton stalks ranged approximately from 7.79 to 42.11 kJ/kg (MJ/tonresidue) in direct

proportionality with the pressure level at density observed from 958 to 1180 kg/m3

as shown in figure (6) and table (3). In absolute terms, the variation of compaction

energy with the different waters content was not varying in value at the same load,

as the compaction energy depends mainly on load and deformation, so the variation

in the value of energy not large. But with different load at all (3mm, 1.4 mm and

0.7 mm) the energies have large variation.

At 3 mm particle size, changing pressure from 3.2 to 6.4 MPa, the increase in the

density and energy were 11.34 % and 108.49% (with water content 6%),

respectively. At water content 15 %, they were 8.56% and 106.78%. With

increasing pressure greater than 6.4 MPa, the increase in energy does not match

with the increase in density. Same results are noticed with the particle size 1.4 mm

and 0.7 mm as shown in figure (6). This trend can be explained by reviewing the

stages of compression. During the first stage of compression, particles rearrange

themselves to form a closely packed mass. During this phase, the original particles

retain most of their properties, although energy is dissipated due to interparticle and

particle-to-wall friction. At high pressures, the particles are forced against each

other even more and undergo elastic and plastic deformation, thereby increasing

interparticle contact. Therefore, it can be recommended to use pressures that are

suitable for compression which are 3.2 and 6.4 MPa (the energy ranged from 7.79 -

16.76 kJ/kg) with different water contents and particle sizes of the material to save

the energy.

The energy required for compaction (with the caloric value for cotton stalks 3938

Kcal/kg) represents about 0.047% - 0.01 % of energy content of cotton stalks.

Misr J. Ag. Eng., January 2005 202

Table (4): Percentage of increasing density (%) and energy required (%) for

the grinds cotton stalks at different loads, water contents and particle sizes

of material (comparing with 3.2 MPa).

Increasing

pressing

pressure

(MPa)

Size 3mm

Water content

6% 15%

Increasing

density (%)

Increasing

energy (%)

Increasing

density (%)

Increasing

energy (%)

3.2 to 6.4 11.34 108.49 8.56 106.78

3.2 to 9.6 13.18 214.56 9.39 211.08

3.2 to 12.8 15.02 321.77 9.71 315.22

3.2 to 16 16.45 429.44 9.81 419.21

Pressing

pressure

(MPa)

Size 1.4 mm

Water content

6% 15%

Increasing

density (%)

Increasing

energy (%)

Increasing

density (%)

Increasing

energy (%)

3.2 to 6.4 1.37 100.96 1.40 101.02

3.2 to 9.6 2.74 202.86 2.34 202.52

3.2 to 12.8 4.11 305.64 4.58 306.45

3.2 to 16 4.57 407.79 4.86 408.54

Pressing

pressure

(MPa)

Size 0.7 mm

Water content

6% 15%

Increasing

density (%)

Increasing

energy (%)

Increasing

density (%)

Increasing

energy (%)

3.2 to 6.4 5.83 103.92 7.22 104.90

3.2 to 9.6 6.74 206.74 7.87 207.96

3.2 to 12.8 7.19 309.55 8.33 311.19

3.2 to 16 7.47 412.36 9.07 415.13

Misr J. Ag. Eng., January 2005 203

Particle size 3 mm

850

900

950

1000

1050

1100

1150

1200

3.2 6.4 9.6 12.8 16.0

Stress (MPa)

Den

sit

y (

kg

/m3)

0

7

14

21

28

35

42

49

1000 2000 3000 4000 5000

Load (kg)

En

erg

y (

kJ/k

g)

6% Density 15% Density6% Energy 15% Energy

Particle size 1.4 mm

850

900

950

1000

1050

1100

1150

1200

3.2 6.4 9.6 12.8 16.0

Stress (MPa)

Den

sit

y (

kg

/m3)

0

7

14

21

28

35

42

49

1000 2000 3000 4000 5000

Load (kg)

En

erg

y (

kJ/k

g)

6% Density 15% Density

6% Energy 15% Energy

Particle size 0.7 mm

850

900

950

10001050

1100

1150

1200

3.2 6.4 9.6 12.8 16.0

Stress (MPa)

Den

sit

y (

kg

/m3)

0

7

14

2128

35

42

49

1000 2000 3000 4000 5000

Load (kg)

En

erg

y (

kJ/k

g)

6% Density 15% Density

6% Energy 15% Energy

Figure (6): Relationship between compaction energy and compaction

density at different loads, water contents and particle sizes of material.

Misr J. Ag. Eng., January 2005 204

CONCLUSION

The following conclusions may be drawn from this study:

- Densities attained under the different parameters used in this study ranged from

958 to 1180 kg/m 3

.

- To grind particle to fine particle, it takes more energy so, particle size of 3 mm

that represents 3.33 – 3.97 times of grinds cotton stalks and about 11.97 – 14.25

times of cotton stalks is recommended instead of particle sizes 1.4 mm and 0.7

mm that represent 3.73 – 3.98 and 3.76 – 4.11 times of grinds cotton stalks,

also represent about 13.37 – 14.31 and 13.5 – 14.75 times of cotton stalks,

respectively.

- Increasing water content (6% to 15%) leads to decrease the density.

- Decreasing particle size from 3 mm to 0.7 mm these leads to the increase density,

because the volume decreases.

- The particle size differ from 3-mm to 1.4-mm the material will be very

compressible; these back to the material will be fine. Therefore, any change in

load the material will be compression. Nevertheless, with particle size, change

from the 1.4-mm to 0.7-mm the material will decrease the compressibility, the

reason back to the particle with 0.7-mm was very fine, there for the material

will need high load but the material compression shows less compressibility.

- The pressures that are suitable for compression are 3.2 and 6.4 MPa (the energy

ranged from 7.79 -16.76 kJ/kg) with different water contents and particle sizes

of the material to save the energy.

- The energy required for suitable compression represents about 0.047% - 0.01 %

of energy content of cotton stalks.

REFERENCES

ASAE Standards, 47th Ed. 2001. S319.3 – Method of determining and expressing

fineness of feed materials by sieving. 573-576. St. Joseph, Mich.: ASAE.

Bhattacharya, S., S. Set, and R. Shrestha. 1989. State of the art of biomass

densification. Energy Resources, 11(13): 161-182.

Bhattacharya,S. C. 2001. Commercialization options for biomass energy

technologies in ESCAP countries. ECONOMIC AND SOCIAL COMMISSION

FOR ASIA AND THE PACIFIC. Regional Seminar on Commercialization of

Biomass Technology4-8 June 2001 Guangzhou, China.

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الولخص العربى

ضلىك عوليت كبص حطب القطي

1 هحوذ هحوىد ابراهين

2ضاهى هحوذ يىص . د. ا

3عبذ العال زكى تايب . د

4بذر شعباى اجى عسام . د

يه ط عا انر ك أ ذعرثش 25 - 18.7ف يصش صم أجان يقذاس انخهفاخ انضساعح إن

. يهاس جح عا1.6أحذ اناسد انطثعح نضادج انذخم انقي يا قشب ي

يه ط أ 1.24 أنف فذا عا ذرخهف عا حان 733ذثهغ يغاحح انقط انضسعح ف يصش حان

اب ذقذس Million T.O.E / year (Tone Oil Equivalent =11.63 MWH) 0.582ذقذس تحان

نزا فا احذ صس االعرفادج ي يخهف انقط اعرخذاي كقد نك تعذ يشس .عح/يه جح 180.6

هي عملية تشكيل المخلفات النباتية على هيئة قوالب منتظمة الشكل سهلة التداول والقولبة . ف عهح انقنثحوالتخزين ذات خواص طبيعية افضل من المخلفات األصلية، حيث يتم كبس المخلفات بعد فرمها وتحويلها

نزا ذعرثش دساعح انضغظ انطاقح . مناسب بواسطة مكابس خاصة تحت ضغط حجمإلى حبيبات ذات

. انطهتا نعهح كثظ انخهف يح

. كليت السراعت جاهعت القاهرة-هذرش هطاعذ 1

. جاهعت القاهرة-كليت السراعت–اضتار الهذضت السراعيت 2

. جاهعت القاهرة-كليت السراعت–اضتار هطاعذ بقطن الهذضت السراعيت 3

. جاهعت القاهرة- كليت الهذضت- بقطن التصوين الويكايكى واالتاج هطاعذ اضتار 4

Misr J. Ag. Eng., January 2005 206

%15، %6 (اعاط جاف) يى عه يحر سطت 3، 1.4، 0.7قذ ذى طح حطة انقط عه اقطاس

يى ثى ذى 63 جشاو ي انخهف ف اعطاح راخ اح يغهقح قطشا انذاخه 70ثى تعذ رنك ذى ضع

. كجى رنك تاعرخذاو يكثظ ذسنك5000، 4000، 3000، 2000 ، 1000ذعشضا الحال يخرهفح

: وقذ اوضحت الذراضت ها يلى

ذى ( يجا تغكال16ان 3.2) كجى 5000 ان 1000ذحد احال ضغط يخرهفح ذرشاح ي -

ز 3و/ كجى 1180 ان 3و/ كجى 968انرصم ان كثافاخ تعذ عهح انكثظ ذشاحد ي

ذثم . (3و/ كجى287) ضعف ي كثافح حطة انقط انطح 4.11 – 3.33انكثافاخ ذقذس

زا فذ ف . (3و/ كجى80) ضعف كثافح حطة انقط قثم ا يعايهح يكاكح 13.5 – 11.97

.ذغم عهاخ انرذال انرصع نهخهف ف صسج قانة ك اعرخذاي كقد

ذقم انكثافح % 15ان % 6ي (اعاط جاف)تاخرالف اانحر انشطت نخهف حطة انقط -

يع االحال انخرهفح (3و/ كجى1178 – 958)ان (3و/ كجى1180- 979)ف انذ ي

االقطاس انخرهفح نهحثثاخ زا ساجع ان ا صادج انحر انشطت شغم حض تانران ذراقص

.انكثافح

يى صادخ انكرافح ي 0.7 يى ثى ان 1.4 يى ان 3تاخرالف اقطاس حثثاخ حطة انقط ي -

يع (3و/ كجى1180 – 1080)ثى ان (3و/ كجى1145 – 1070)ان (3و/ كجى958-1140)

االحال انخرهفح انحر انشطت انخرهف زا ساجع ان ا ذاقص حجى انحثثاخ ؤد ان

.شغم حض اقم تانرثعح ذضذ انكثافح

يى فا انخهف ظش قاتهح اكثش نعهح انكثظ، نك 1.4يى ان 3عذيا ذرغش حجى انحثثاخ ي -

يى فا انخهف ظش قاتهح اقم نعهح انكثظ زا 0.7 يى ان 1.4عذيا ذرغش حجى انحثثاخ ي

.ساجع ان ا حجى انحثثاخ صغش جذا تانران انفشاغاخ اقم

يجاتغكال الخفاض انطاقح انطهتح نعهح انكثظ 6.4 – 3.2ذص انذساعح تكثظ انخهف عذ ضغظ

ال انضادج ف انضغظ ؤد ان صادج كثشج ف انطاقح انالصيح نعهح انكثظ، تاء عه رنك فا انطاقح

ي انطاقح % 0.01 ان 0.047اعثح ذثم انغرهكح ف عهح كثظ حطة انقط عذ انضغط انى

.انحشاسح اناذجح ي حشق يخهف انقط

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