EXPERIMENT
ROTARY DRUM FILTER PRESS
1. Objective
To study the filtration characteristics of a slurry (CaCO3) in
rotary drum filter. To explore the variables effecting the filtration rate.
2.
Introduction
The Rotary Vacuum Drum Filter belongs to the bottom feed group and
is one of the oldest filters used in chemical
industrial applications. Rotary vacuum
filter drum consists of a
large rotating drum covered by a cloth. This drum rotates in a tub of liquid to
be filtered. The liquid that is to be filtered is sent to the tub below
the drum. The drum rotates through the liquid and the vacuum generated sucks
liquid and solids onto the drum. The liquid portion is sucked through the
filter media to the internal side of the drum, and the filtrate left is pumped
away. The rotating drum continuously takes in feed from slurry tank and blows
off the cake formed on the surface. The cake formed is dried using a vacuum pump which continuously sucks the cake
and take the water out of it.
3. Procedure
The basic steps in the
filtration process are:
·
Cake
Formation
·
Cake
Washing & Drying
·
Cake
Discharge
First we need to clean
the vessel, rotary drum and scrape out all the residuals left on the filter
medium and make sure that all the valves are closed. 2.83 kg of
powder and 25 L of water are slowly added to
the feed tank. Power supply and the agitator knob needs to be switched on
followed by the feed pump. For the mixing to be easy and in proportion feed
valve is opened. Mixing is done for 10-15 mins. After the mixing is done, feed
valve is partially closed and the rotary drum valve is opened. The slurry is
pumped into the trough and as the drum rotates it is partially submerged in the
slurry (about 30 %). The vacuum generated draws the liquid and air through the
filter and thus forms the cake. Solid are trapped on the surface of filter and
with the help of scrapper (knife) scrap out the solid cake. In the end note
down the time for increase in every centimetre in height of vacuum tank.
Cleaning
of the apparatus:
The feed tank and rotary drum are washed with clean
water. Water collected in the vacuum tank is also drained off. All the valves
are closed.
4. Analysis
a)
Feed =
kg
b) Water
feed = kg
c) Total
feed = kg
d) Concentration
= 10%
e) Volume
per cm= ml
f) Filtrate
= kg
g) Cake
formed = kg
h) Slurry unused = kg
i)
Slurry used= kg
j)
Area of filter A = πd2 /4= ft2
k) P1=
mm of Hg
l)
P2 =
mm of Hg
m) ΔP =
mm of Hg = KPa
n) Material balance
Total
mass in =Total mass out
Mass
of H2O + Mass of CaCO3 = Mass of H2O +Mass of CaCO3 +Unused slurry
a kg
+ y kg =
b kg + Z kg +
c kg
o) Area
of cake considering it to be a cuboid=
5. Result and Discussions
1)
The
specific cake resistance is =
2)
The
graph between ∆θ/ ∆V and V is a linear
curve.
3)
Slope= s/L2
