The
paper mills, based in Nigeria, is a group of two paper mills. Originally
International Paper operations, they are now owned by the Nigeria family group.
Both mills produce paper using sugar cane bagasse as furnish. There are many
sugar cane mills in the area, so a year-round supply of raw material is
assured.
Commissioned
in 1990, today their #2 Mill produces 330 metric tons of paper per day. This
paper is used for copier paper, although books and notebooks are also produced
with it. These paper Mills has recently purchased a Model VP-24 screw press
which will dewater the primary clarifier underflow at this mill.
The
project was driven by two factors: environmental and economic. From the
environmental standpoint, using the press will eliminate a landfill operation.
This landfill can cause run-off and groundwater contamination, besides
presenting an ever-growing environmental situation.
Economically
the press has a quick payback because the press cake will be dry enough to be
combined with their boiler fuel. The press cake has a BTU value of
approximately 8,500 BTU per pound of dry matter (compared to 10,000 for coal). These
paper Mill's B&W boilers burn coal. By blending the press cake with this
coal, a reduction in coal consumption will result. The use of such biomass fuel
has been receiving much attention at paper mills because of increasing energy
costs.
The
load to be dewatered is 40 metric tons per day (MTPD) of dry solids. It was
felt that a Model VP-16 could likely have handled the load. The VP-24 was
selected on a conservative basis, anticipating future operating conditions. It
is also possible that it may be used to remediate the material in their
landfill.
It
is noteworthy that the mill already burns 70 MTPD dry solids of chaff and pith
that is separated ahead of the digester. This material is pumped to an Andritz
belt press where it is dewatered to 40% solids prior to burning.
These
paper Mills made use of the Vincent rental fleet. A Model CP-4 press was air
freighted to Cali and used for a variety of testing. With this testing it was
determined that no pre-thickening or polymer will be required, and press cake
with a solids content of 50% can be produced without undue strain or problems.
Rent was waived for the test period, and a Vincent engineer assisted at no
charge.
The
clarifier is an Eimco, 150' in diameter, handling 9000 gpm. Sand is separated
ahead of the clarifier in order to reduce torque loading, and the flow is
neutralized. The reject material, mostly medulla or pith, settles to a thick 5%
underflow. It is because of this relatively high underflow consistency that no
pre-thickening is required.
The
original equipment at the WWTP (wastewater treatment plant) consisted of a
small Eimco rotary drum screen, followed by a pair of Andritz belt presses. The
rotary drum screen is only, approximately, 3' diameter by 5' long. This
increases the underflow consistency from 5% to 8%. The belt presses, now worn
and in need of overhaul, are about 3 meters wide. The cake produced by the belt
presses normally has only 15% solids.
The
new installation will place the screw press in parallel with the belt presses.
That way it will be possible to retain the belt presses, at least for the time
being, as back-up. It will also permit the rebuilding of these belt presses. In
the future the belt presses may be used to for pond remediation, dewatering
sludge from the mill's treatment lagoons.
The
Vincent press was selected over competition because we were able to clearly
demonstrate the performance being guaranteed. Because it was an export
contract, strong financial assurances were offered in the form of two Letters
of Credit. The first L/C, issued by Bank of America to These paper Mills,
assures These paper Mills that their down payment money will be refunded should
Vincent fail to ship them the press as promised. The second L/C will assure These
paper Mills that Bank of America will refund the full purchase price of the
press should These paper Mills elect to return the machine. Customer
satisfaction is guaranteed.
Reference:
SUGAR
CANE PAPER/Bagasse Paper Mill _ Vincent Corporation.htm