IN FILTER PRESSES."
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Henry Rawlings at the Office of the,
Commissioners of Patents on the 13th September 1878.
HENRY RAWLINGS, of 108, Saint Martin's Lane, Westminster.
IN FILTER PRESSES."
"
IMPROVEMENTS:
In the construction of filter presses in which the substance, semi-fluid, or liquid
to be treated is forced by pumping or other pressure into chambers, compartments,
or divisions, provided with porous substances, materials, or fabrics, in, around, or
between them, and through which the fluid portion escapes or is forced, a necessity.
generally exists for entirely disconnecting, detaching, or otherwise taking asunder
such a machine or press before the substance so compressed can be removed.
To facilitate the working of such presses I construct a strong framework of
iron or other suitable material, through the base of which a shaft or column either
with or without a table top, according to circumstances, is caused to rise or fall by
means of a lever, a screw, hydraulic pressure, or any combination of them.
Upon a strong table or platform made of iron or other suitable material, and
mounted upon wheels, I place the rings or other framework forming the chamber,
chambers, divisions, or compartments (with the filtering material in, around, or
between them) in alternate succession, and upon the top of them a strong cover is
placed. The table or platform is now wheeled immediately over where the shaft or
column rises and falls, and as the shaft or column rises the series of rings forming
the chambers are pressed tightly against each other and the top of the first-named
framework to any requisite extent. The substance or semi-fluid to be treated may
be introduced into the chambers at the top, or at any other convenient point by
pumping or other pressure, the moisture exuding through the materials or fabrics
used for that purpose. When the chambers or compartments are charged the shaft
or column is lowered, the platform on wheels wheeled out, and another platform
similarly arranged put in the vacated place, and the process proceeds as before,
being made almost continuous.
The rings from which the chambers or compartments are built up I should
preferably make of metal, either cast hollow or made from plates rivetted or
otherwise secured together, and filled if requisite with any convenient substance
071

page_text: lighter in weight. This form of ring also affords facilities for introducing a
circulating stream of hot water in cases requiring it.
In dealing with fluids or semi-fluids in which it may be desirable to separate the
water or other fluid from the more solid matters with an accelerated speed, I make
another filtering chamber distinct from, although intimately connected with the
chambers, compartments, or divisions in which the substance is compressed, and
communicating therewith, either by pipes, or by or through any substance, material,
or fabric suitable for the purpose. The filtering process of this chamber consists of
a hollow and perforated tube or pipe, on which are arranged dises or plates of metal
or other convenient material, with holes through them sufficiently large for their
moving easily upon the pipe or tube; and between each and every one of them
some suitable fabric or material is placed with a hole in it to correspond with that
in the plates, but larger in outside measurement than the plates or discs enclosing it.
These being arranged alternately on the perforated pipe or tube are inserted in the
filtering chamber, with one or both ends of the pipe or tube projecting through it,
water-tight; and by the application of a screw or lever any desired degree of
compactness or compression of the plates or discs upon the filtering material or
fabric between them can be obtained, and which will regulate the speed of flow of
the liquid through it. The direction in this case of the flow of the liquid through
the filtering material or fabric is from the outside of this filtering process to the
centre, thereby concentrating the discharge of the liquid to the outlets of the pipe
at either or both ends. This also allows the application of a reversing action by
which the solid matters which have entered the pores or interstices of the filtering
fabric may be conveniently flushed off by pumping or other pressure without
removing or disturbing the filter. Rotating the filtering process with a stream of
water directed into it will also clean it centrifugally. This filtering chamber may
also be used as a distinct and separate filtering apparatus or press, and the residue
removed through a man-hole by flushing off or other convenient arrangement. It
also presents great facilities for applying heat by running circulating hot water
pipes through it when necessary.
In the necessity of pumping gritty substances or semi-fluids into presses, and
which have the tendency of causing great wear and tear of the pump, plunger, and
machinery, I interpose an elastic or semi-elastic diaphragm between the plunger,
which works in a water-tight chamber, and the substance or semi-fluid so pumped
for the plunger as it rises and falls is followed by this diaphragm, which creates
the same relative action as if the plunger was immersed in the substance or semi-
fluid so pumped.
For valves I prefer to use some elastic or semi-elastic substance impinging upon
a seating having a knife edge, the other portion of which being honey-combed, so
that sufficient support may be afforded to the elastic or semi-elastic valve without
giving any rest or lodgment to any solid matters.