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Screw press and itsperformance
Pragati Singham
M.Tech (FPEM)
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INTRODUCTION
It is the simplest machine for separation of solidsand
liquids
It is a cage style press
It is used for separation of !
"ils from #arious oilseeds
$ruit %uices
Screw pressing is a continuous operation hencethese are also
known as 'epellers
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TYPES OFSCREW PRESS
Horionta! "cre#$re""
H%&er inc!ine' "cre#$re""
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CONSTRUCTION WORIN*
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PRINCIP+E
It works on the principle of *com$re""ion an'
"hear,
Compression ratio + #olume displaced per re#olution at thefeed
end
#olume displaced per re#olution atdischarge end
Compression cur#e
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DESI*N OF SCREW PRESS
Diameter o- "ha-t ('") where
T + torque transmitted ,y shaft
-. + yield stress
+oa' !i-te' & "cre# (We) where /m + mean thread diameter
T + torque transmitted ,y shaft
0 + coe1cient of friction
2 + tapering angle
3n+ thread (lift) angle
Pre""%re 'e/e!o$e' & "cre# threa' (Pr)
where4p + pressing area
h +screw depth at mapressure
area (discharge end)
n + no of threads
5all et al 678
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Ca$acit(0e) where/s + diameter of the screwthread
ds + ,ase diameter of the
screw shaft Ps + screw pitch
9s + rotational speed ofthe screw shaft
: + filling factor
; + ,ulk density
Po#er re1%irement(Pe) where
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PERFORM2NCE OF SCREW PRESS
/esign a screw press whose speci=cationsare>
/s + 6.. mm ds + ?. mm Ps + ?.mm
9s + 7.8@ rpm A + .B + DE.kgFm@
-. + G.. 9FmG T + 7GB?D6 9m /m + D? mm
0 + .6? 3n + 6?.
3 + @.
h + ?mm n + 7 6 (tan6?.
Cos @.)
+34.895
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+ 7GB?D6 D?FG [email protected] .6?(6>.6? tan @.cos 6E7B.)
+6:.99W
Pre""%re 'e/e!o$e' & "cre# threa' (Pr)
+ @6E D? 7 ? + 35;5:.99mm:
+ DGBB 6... + ;.96 N (?.)G ?. 7.8@ .B DE.
+ 849.:48 =g;8W
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YIE+D ? EFFICIENCY? E@TR2CTION +OSS
"il yield (") +
"il e1ciency ("J) +
Jtraction loss (JK) +
where
"J + L etraction e1ciency
" + L oil yield JK + L etraction loss
M"J + weights of oil etracted(g)
MRC + residual cake (g)
M$S + feed sample (g)
+ oil content of seed in decimal
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3. NUMERIC2+ Soy,ean seeds contain E.L oil on weight ,asis and
EG g
of oil is etracted ,y screw press from 6.. g of soy,eanseeds
Calculate the oil e1ciency of the soy,ean seeds
weight of soy,ean(M$S) + 6.. g
4mt of oil present() + .E.
4mt of oil etracted(M"J) + EG g
"il e1ciency ("y) +
+ 6.. EG L
.E 6..
+ 6.? L
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:. NUMERIC2+
Calculate the eNecti#eness of an screw press which yields @D kg
oilcontaining ?L impurities from 6.. kg mustard seeds The oil
content ofthe mustard seeds is @BL
Meight of mustard seeds + 6..kg
Jpected yield + @B kg"il etracted + @D ! (@D of ?L)
+ @D> .6B?
+ @?6?kg
JNecti#eness + calculated yield 6..
Jpected yield
+ @?6? 6..
@B
+ 8.:A B
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REFERENCES
/eli S $arah asturah Ta%ul 4ris and Man 9adiah M
4 The JNects of physical parameters of the screw press
oilepeller on oil yield from Nigella sativa L seeds.International
Food Research Journal 18(4): 13671373(!"11)
5all 4 S 5olowenko 4 J & Kaughlin 5 Q (G..G)
Schaums outline series theory and pro,lems of machinedesign (6st
ed)# Ne$ %or&: 'cra$ill *o+,anies- Inc#-(*ha,ter 1!)#
Han'&oo= o- Foo' Proce""ing E1%i$ment,y Qergios/ Sara,akos
4thanasios J osaropoulos
httpUFFwwwreinartVdeFindephpWid+GD&K+6
httpUFFwwwfaoorgFdocrepFt.?@[email protected]
http://www.reinartz.de/index.php?id=27&L=1http://www.reinartz.de/index.php?id=27&L=1http://www.reinartz.de/index.php?id=27&L=1
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T549 "X
