Improvements in Forcing Fluids and Semi-fluids by Means of Compressed Air and Apparatus therefor.
Year: 1885

page_text: Improvements in Forcing Fluids and Semi-fluids by Means of
Compressed Air and Apparatus therefor.
We SAMUEL HENRY JOHNSON and CHRISTOPHER CLARKE HUTCHINSON both of
the Engineering Works Stratford in the County of Essex Engineers do hereby
declare the nature of our invention for "IMPROVEMENTS IN FORCING FLUIDS AND
SEMI-FLUIDS BY MEANS OF COMPRESSED AIR AND APPARATUS THEREFOR to be as
follows:-
"
It has been found inconvenient or impracticable in the case of certain fluids and
semi-fluids to employ pumps for forcing them under pressure in consequence of the
specific character of the fluids. Either they are corrosive and act on the materials
from which most pumps are constructed, or else in the case of semi-fluids containing
large proportion of fibrous and other matters have a tendency to accumulate and
obstruct the valves and other working parts of pumps.
In such cases it has been heretofore common to employ compressed air for the
purpose of forcing such liquids and dispense entirely with pumping them and the
consequent difficulties above indicated. The system heretofore commonly adopted
has been to collect the material which it is desired to force, into a receptacle which
can be hermetically closed, and then to close it. The receptacle, is provided with
an inlet pipe by means of which compressed air is introduced above the level of the
material therein. It is also provided with an outlet pipe from the lower part by
means of which the material is conducted away under the pressure of the air in
the upper part of the receiver. This arrangement is now principally used for
forcing corrosive fluids to a superior level, such as sulphuric acid in sulphuric
acid chambers, and more frequently still for forcing semi-fluids of a fibrous
nature, such as sewage sludge into filter presses. It is however as compared
with pumping a costly operation requiring considerable more power. And it is
also obvious from the short description given above of the method usually practised
that when it is desired to recharge the receptacle with the liquid to be forced it
becomes necessary to permit the compressed air to escape before opening the vessel
for another charge. In the compressed air thus blown away into the atmosphere a
large proportion of the whole potential energy necessary for forcing the liquid by
this system is lost. Now the object of this invention is to secure the advantages
of forcing with compressed air in the cases above mentioned without the dis-
advantages above indicated and to this end we proceed as follows:-
We provide a series of two or more hermetically closed receptacles and where it
is desired to maintain a continuous pressure of the material in the forcing main,
such as would be requisite when a series of filter presses are being worked therefrom.

page_text: We prefer to employ three receptacles. We fill one of the receptacles with
compressed air to the pressure at which we desire to work. We then fill another
of the receptacles with the material to be forced: we then open a cock or valve
communicating with a pipe which connects the top of the first and second receivers.
We then pump water into the first receiver by any convenient pump of ordinary
construction, and by this means we displace the air in the first receiver forcing it
into the second, which in its turn forces the material from the second receiver into
the pressure main. As soon as the first receiver becomes filled with water a float
is raised which closes a valve on the end of the pipe by means of which the air
flowed into the second vessel. The induction pipe for the water is provided near
the pump with a loaded safety valve which is adjusted to deliver the excess of
water when the receiver is full being loaded slightly above the working pressure
in the first receiver when the air is being displaced with the water. The water
pump is then stopped, and the cock in the air pipe by means of which the com-
pressed air was transferred from the first to the second receptacle is then closed.
At this stage the proportions of the different parts are so arranged that the second
receiver which is of equal size with the first shall contain all the compressed air
forced out of the first receiver at a slightly higher pressure and a small quantity of
the material in process of being forced by the pneumatic pressure. The first
receptacle is provided with an outlet cock and air cock at the top communicating
with the atmosphere and these being opened the water is allowed to run away.
So soon as the second receptacle is emptied a float at the bottom of it closes a
valve which prevents the air escaping into the pressure main for the material being
forced. N° 2 receptacle is then in the condition of N° 1, at the commencement of
the operation, namely, filled with the same volume of compressed air and under
the same pressure. The third receptacle which has been previously filled with the
material to be forced is treated in all respects in the same way as the second
receptacle had previously been when the material from it was being forced by the
compressed air from the first receptacle, the water being pumped into the second
receptacle and otherwise manipulated as already described in reference to the first
receptacle. The first receptacle is then filled with the material to be forced by
allowing it to flow in by gravitation or otherwise and then it in its turn is ready
to have its contents displaced by means of the compressed air from the third
receptacle so soon as its contents have been forced out, and so the process is repeated
continuously and by this means we obtain the following advantages.
:
1stly, Materials can be forced without pumping them which otherwise would
obstruct or destroy the valves and other working parts of a pump using only the
amount of energy necessary to work an ordinary pump.
2ndly. By using the same volume of compressed air over and over again without
allowing it to expand we avoid the loss of power which occurs in the older method
of pneumatic forcing by the heat evolved during the compression of the air.
3rdly. We avoid the waste of energy which occurs when the compressed air is
blown away to waste after each forcing operation.
There are other advantages which result from the employment of a pneumatic
system for forcing materials into filter presses such as is due to the elasticity of the
compressed air regulating the supply to filter presses and adapting itself to the
requirements of the work to be done in a way that would not be practicable with
any ordinary pump, but these advantages are not peculiar to this system of
pneumatic forcing but are common to the pneumatic forcing system now commonly
employed as above described,

page_text: Compressed Air and Apparatus therefor.
We SAMUEL HENRY JOHNSON and CHRISTOPHER CLARKE HUTCHINSON both of
the Engineering Works Stratford in the County of Essex Engineers do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:
It has been found inconvenient or impracticable in the case of certain fluids and
semi fluids to employ pumps for forcing them under pressure in consequence of the
specific character of the fluids. Either they are corrosive and act on the materials
from which most pumps are constructed, or else in the case of semi fluids containing
large proportion of fibrous and other matters have a tendency to accumulate and
obstruct the valves and other working parts of pumps.
In such cases it has been heretofore common to employ compressed air for the
purpose of forcing such liquids and dispense entirely with pumping them and the
consequent difficulties above indicated. The receptacle is provided with an inlet
pipe by means of which compressed air is introduced above the level of the
material therein. It is also provided with an outlet pipe from the lower part by
means of which the material is conducted away under the pressure of the air in the
upper part of the receiver. This arrangement is now principally used for forcing
corrosive fluids to a superior level such as sulphuric acid in sulphuric acid chambers,
and more frequently still for forcing semi-fluids of a fibrous nature, such as sewage
sludge into filter presses. It is, however as compared with pumping, a costly
operation requiring considerably more power. And it is also obvious from the
short description given above of the method usually practiced that when it is
desired to recharge the receptacle with the liquid to be forced it becomes necessary
to permit the compressed air to escape before opening the vessel for another charge.
In the compressed air thus blown away into the atmosphere a large proportion of
the whole potential energy necessary for forcing the liquid by this system is lost.
Now the object of this invention is to secure the advantages of forcing with
compressed air in the cases above mentioned without the disadvantages above
indicated and to this end we proceed as follows:-
We provide a series of two or more hermetically closed receptacles and where it
is desired to maintain a continuous pressure of the material in the forcing main,
such as would be requisite when a series of filter presses are being worked there-
from. We prefer to employ three receptacles. We fill one of the receptacles with
compressed air to the pressure at which we desire to work.
We then fill another of the receptacles with the material to be forced; we then
open a cock or valve communicating with a pipe which connects the top of the
first and second receivers. We then pump water into the first receiver by any
convenient pump of ordinary construction, and by this means we displace the air
in the first receiver forcing it into the second, which in its turn forces the material
from the second receiver into the pressure main. As soon as the first receiver

page_text: becomes filled with water a float is raised which closes a valve on the end of the
pipe by means of which the air flowed into the second vessel. The induction pipe
for the water is provided near the pump with a loaded safety valve which is
adjusted to deliver the excess of water when the receiver is full being loaded
slightly above the working pressure in the first receiver when the air is being
displaced with the water. The water pump is then stopped, and the cock in the
air pipe by means of which the compressed air was transferred from the first to
the second receptacle is then closed. At this stage the proportions of the different
parts are so arranged that the second receiver which is of equal size with the first
shall contain all the compressed air forced out of the first receiver at a slightly
higher pressure.and a small quantity of the material in process of being forced by
the pneumatic pressure. The first receptacle is provided with an outlet cock and
air cock at the top communicating with the atmosphere and these being opened
the water is allowed to run away. So soon as the second receptacle is emptied a
float at the bottom of it closes a valve which prevents the air escaping into the
pressure main for the material being forced. No 2 receptacle is then in the
condition of N° 1, at the commencement of the operation, namely, filled with
the same volume of compressed air and under the same pressure. The third
receptacle which has been previously filled with the material to be forced is
treated in all respects in the same way as the second receptacle had previously
been when the material from it was being forced by the compressed air from the
first receptacle, the water being pumped into the second receptacle and otherwise
manipulated as already described in reference to the first receptacle. The first
receptacle is then filled with the material to be forced by allowing it to flow in by
gravitation or otherwise and then it in its turn is ready to have its contents
displaced by means of the compressed air from the third receptacle so soon as its
contents have been forced out, and so the process is repeated continuously; and by
this means we obtain the following advantages 1stly Materials can be forced
without pumping them which otherwise would obstruct or destroy the valves and
other working parts of a pump using only the amount of energy necessary to work
an ordinary pump-2ndly By using the same volume of compressed air over and
over again without allowing it to expand we avoid the loss of power which occurs
in the older method of pneumatic forcing by the heat evolved during the com-
pression of the air. 3rdly We avoid the waste of energy which occurs when the
compressed air is blown away to waste after each forcing operation.
There are other advantages which result from the employment of a pneumatic
system for forcing materials into filter presses such as is due to the elasticity of
the compressed air regulating the supply to filter presses and adapting itself to the
requirements of the work to be done in a way that would not be practicable with
any ordinary pump, but these advantages are not peculiar to this system of
pneumatic forcing but are common to the pneumatic forcing system now
commonly employed as above described.
In order that our said invention may be most fully understood and readily
carried into effect, we will proceed to describe the drawings hereunto annexed.
:
DESCRIPTION OF THE DRAWINGS.
Figure 1 is an elevation of apparatus arranged in accordance with our invention.
Figure 2 is a plan, and Figure 3 is, a transverse vertical section of the same.
The apparatus as here shown is suitable for supplying sewage sludge to filter
presses by which it is compressed into cakes, and like apparatus may also be
employed in forcing other fluids or semi-fluids either for the supply of filter presses
or for other purposes.
A1, A2, A3 are hermetically closed vessels, they are similar the one to the other,
and they are connected at the top by pipes B on which air cocks B¹, B¹, are
provided.
•

page_text: Each vessel communicates with a main C through which the vessel is charged;
the connection is by a passage in which is a valve which can be opened or closed
at pleasure. These valves are operated by means of hand wheels D. D.
The vessels A¹ A³ A³ also communicate by other passages with a discharging
main which also can at pleasure be closed and opened by valves; the valves for
this purpose being operated by means of hand wheels F.
The filter presses, to which sludge is to be supplied, are put into communication
with the main E when required by opening valves provided for the purpose, or
the main E may lead the fluid or semi-fluid matter whatever it may be to any.
place where it may be required.
At the lower part also of each vessel a pipe G is connected, and this leads to
other pipes H and I, which are respectively the delivery and the suction of a
water pumping apparatus K.
H' and I are cocks by opening and closing which either vessel can at pleasure
be connected with the pump suction or with the delivery pipe.
Within each vessel there is a ball valve L of metal covered with vulcanised
india rubber-it is sufficiently light to float on the sludge or contents of the vessel
and the purpose which it serves is to automatically close the connection between
the vessel and the main E immediately the vessel is empty and also to close the
communication between the vessel and the pipe B when the vessel is completely full.
The apparatus may be used as follows:-
Suppose the vessel or receptacle A¹ to be full of sewage sludge, the vessel A³ to
be full of compressed air and the vessel A³ to be full of water. The vessel A¹ is
put in communication with the main E. All other cocks in connection with this
vessel are closed excepting that the pipe B is opened to connect this vessel at the
top with the neighbouring vessel A. All cocks in connection with the vessel A²
are closed except that which connects it with the delivery pipe H of the pump.
All the cocks in connection with the vessel A³ are closed with the exception of that
which connects it with the suction pipe I of the pump. The pump being now set
to work water is drawn from the vessel A³ and forced into the vessel A' thereby
displacing the compressed air which the vessel already contains. This compressed
air enters the vessel A¹ whilst the sludge is forced from this vessel into the main E.
When the vessel A¹ is empty the valve L within it closes the passage to the
main E whilst the corresponding valve of the vessel A* closes that vessel at the
top. The pumping apparatus may continue in motion any water which it may
draw escapes by the weighted valve M and passes into the service tank N with
which also the suction of the pumping apparatus can be connected at pleasure.
The vessel A³ is now empty and there is a partial vacuum within it. The next
operation is to fill this vessel with sludge which is done by opening the valve D
the sludge then flows in until the vessel is filled or nearly so.
The arrangement shown in the drawing is suitable where the sludge to be drawn
from a source raised a few feet above the main C.-but if it be required that the
vacuum in the. vessel A³ should raise the sludge from a lower level, then the
pumping apparatus K should also be placed lower down, say some 12 feet below
the bottom of the vessels A1, A2, A3, so that the descent of the water from them
may aid the action of the pump. The vessel A³ being now full of sludge whilst
the vessel A¹ contains the compressed air and A* contains the water the cycle of
operations recommences. The compressed air is transferred from A' to A³, the
vessel A is discharged into the main E and the water is drawn out from the
vessel A*. Thus the operation goes on, the volume of compressed air being
transferred from vessel to vessel without loss of energy. Any description of
pumping apparatus may be employed, and in some cases the water under pressure
may be drawn from an elevated cistern or other source, and the use of a pump in
direct connection with the apparatus dispensed with.
It is obvious that the air may in the first instance be compressed by forcing
water into one or more of the vessels whilst another serves as a receiver for the air
which the water displaces.

page_text: Any leakage of compressed air which may take place may be made good by not
quite filling the vessels with sludge and allowing some air also to be in them when
commencing to discharge the contents.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
1. Our improvement in forcing fluids and semifluids consisting in displacing the
same by means of a volume of compressed air kept. constantly under pressure and
transferred from vessel to vessel substantially as described.
2. Our improvement in forcing fluids and semifluids consisting in introducing
water under pressure into a vessel containing compressed air, thereby causing the
compressed air to pass into another vessel containing the fluid or semifluid and to
eject the same; this operation being repeated with the same quantity of compressed
air so as to avoid the waste of the energy expended in compressing the air substan-
tially as described.
3. The apparatus for forcing fluids and semifluids substantially as herein
described and represented by the annexed drawings.
CARPMAEL & Co.,
Agents for the Applicants.