IMPROVED MEANS FOR REMOVING CALCAREOUS AND OTHER IMPURITIES FROM WATER
Year: 1881

page_text: LETTERS PATENT to Arthur William Lovell Reddie, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Patent Agent, for an Invention
of "IMPROVED MEANS FOR REMOVING CALCAREOUS AND OTHER IMPURITIES
FROM WATER." A communication from abroad by Monsieur le Baron Nicolas
de Derschau, of St. Petersburg, in the Empire of Russia.
PROVISIONAL SPECIFICATION left by the said Arthur William Lovell
Reddie at the Office of the Commissioners of Patents on the 12th September
1881.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery Lane,
in the County of Middlesex, Patent Agent. "IMPROVED MEANS FOR REMOVING
CALCAREOUS AND OTHER IMPURITIES FROM WATER." [A communication from
abroad by Monsieur le Baron Nicolas de Derschau, of St. Petersburg, in the Empire
of Russia.]
r
This Invention relates to improved means for filtering water, and is especially
adapted to the removal of the various calcareous salts and other impurities contained
therein, so as to render the said water suitable for use in steam boilers.
In carrying this Invention into effect the water to be purified is caused to pass
under pressure through a series of cast iron cylinders fitted internally with removable
linings which contain a special filtering medium. These linings are made in sections
for convenience of removal and replacement. A series of two-way cocks regulates
the admission of water from the main supply pipe to the underside of the several
cylinders, and another series of cocks allows of the discharge of the filtered and
purified water from the top of the said cylinders in any desired order. When the
mass of filtering medium within the removable lining of any one of these cylinders
needs renewing, the sections of the said lining are removed and quickly replaced by
other sections previously charged with the homogeneous mass of filtering material,
the composition of which will now be described.

page_text: This filtering material is made of equal parts by weight of magnesia and sifted
saw dust, the latter being preferably that obtained from soft woods, and free from
foreign bodies and grit.
These two substances are thoroughly mixed in a dry condition within a rotating
drum or by other suitable means. Water to the extent of one half the weight of
the magnesia is then gradually added, and the mass is stirred. Hydrate of
magnesia Mg O2 H2 is formed, which adheres closely to the large surface presented
by the grains of sawdust. The mass is then dried by exposure to the air, and the
surplus moisture is evaporated, leaving a porous mass of the nature of a coarse and
hard powder. The adhesion of the hydrate of magnesia is remarkably close, and
is not weakened by mechanical action or by washing. The cylinders are thus
prevented from becoming foul, and the magnesia cannot be carried away by the
water, which is moreover caused to ascend slowly through the mass of filtering
material. Thus water charged with the bi-carbonates of lime and magnesia, as
well as with sulphate of lime, is quickly freed from these calcareous salts after it
has been a short time in contact with the large surface of hydrate of magnesia
within the cylinders. A speedy and complete reaction is effected even at low
temperatures.
The hydrate of magnesia by the absorption of carbonic acid becomes neutral
carbonate of magnesia, and precipitates the carbonate of lime in the form of crystals
of arragonite on the surface of the saw dust.
The neutral salt, carbonate of magnesia, being soluble decomposes the sulphate
of lime, precipitating the carbonate of lime, and leaving the sulphate of magnesia
in solution. This last substance replaces the gypsum, so dangerous as an incrustant
of boilers, while the sulphate of magnesia, being very soluble, cannot impregnate
the water in the boilers to such an extent as to form a deposit. The filtering
medium will first require renewal within the first of the cylinders through which
the water is passed, and the supply and discharge pipes are therefore so arranged
and fitted that the water may be caused to first enter any one of the series of
cylinders, and flow through it and the other cylinders in any desired order. The
cylinders are connected together by short pipes.
The capacity of the apparatus being ascertained, it will be easy to know when
the filtering medium in the several cylinders of the series should be renewed.
By these means the inconveniences attending the employment of the ordinary
solvents are obviated.
In cases where the water to be purified is rich in sulphate of lime and poor in
carbonic acid, an analysis of the water will at once determine the quantity of basic
carbonate of magnesia (5 Mg O, CO₂) which should be added in place of the oxide
of magnesium.
For waters rich in carbonic acid it is advisable to use caustic lime, which should
be introduced in a determined quantity into the non purified water before the latter
passes into the first of the cylinders in order to absorb the greater part of the
carbonic acid. This allows of economy in the use of magnesia, and a less quantity
of neutral carbonate of magnesia is held in solution in the purified water. This
process as applied to waters rich in carbonic acid possesses the great advantage of
preventing any excess of caustic. lime from passing off in solution in the purified
water. The presence of the basic magnesia 5 Mg O. CO, with Ca O produces two
insoluble salts Mg O and Ca CO₂.
In all these cases the mode of operation is the same as that already described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur William Lovell Reddie in the Great Seal Patent Office on the
10th March 1882.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery Lane,
in the County of Middlesex, Patent Agent. "IMPROVED MEANS FOR REMOVING
CALCAREOUS AND OTHER IMPURITIES FROM WATER." A communication from
abroad by Monsieur le Baron Nicolas de Derschau, Engineer, of St. Petersburg, in
the Empire of Russia.
This Invention relates to improved means for purifying water, and is especially
adapted to the removal of the various calcareous salts and other impurities contained
therein, so as to render the said water suitable for use in steain boilers.
In carrying this Invention into effect the water to be purified is caused to pass
under pressure through a series of cast iron cylinders fitted internally with removable
linings which contain a special filtering medium.
In the accompanying Drawing this apparatus is represented in front elevation,
plan view, and transverse section at Figures 1, 2, and 3, and consists of four or more
cylinders of cast iron I., II., III., IV., mounted on a wooden foundation, the size
of the cylinders depending on the volume of water to be purified in 12 hours
continuous working.
h1, h2, h3, h, are two-way cocks opening to the right and left, and serving to
introduce the water, which enters the pipe z at a, and in rising passes through the
purifying mass within the apparatus at the rate of one cubic metre in 15 minutes,
and thus at a speed of 0-23 per minute in each of the cylinders.
Iron tubes 7, 1, 2, 3, connect the cylinders and conduct the water from one to
the other.
The discharge cocks v¹, v³, v³, v, empty in turn the purified water into the
common pipe L, whence it passes to its destination, it may be to the feed water tank
of a boiler.
At the commencement of the operation the cocks of the apparatus are turned in
the following manner :-h', open on the left side; h², ha, h³, open on the right side;
v, v, vs, closed, and v open.
The four cylinders are fitted with the purifying mass of homogeneous consistency
to be hereafter described.
To facilitate the charging of the cylinders several cylindrical linings of zinc or
other suitable material with perforated bottoms are employed, of less height than
the large cylinders; these linings are filled beforehand and placed one upon the
other.
The edge of the upper cylindrical lining is provided with a ring of rubber on
which the cover of the large cylinder presses, so as to hermetically seal the space S
and prevent the non-purified water from penetrating.
The water to be purified enters by the cock a with a head pressure of from
1m 50 to 2 metres, passes by the index W, and fills the pipe Z situated below the
cylinders.
The cocks h2, h3, h4, being closed on the left side, and the cock h' closed on the
right side, the water is caused to ascend first into the cylinder No. I. After it has
traversed the purifying material and yielded a large portion of calcareous salts, it
gradually passes by the connecting pipes r,, r², to the cylinder No. IV., whence
it issues by the cock at one side chemically freed from calcareous salts, and it
then flows into the feed water tank.
This automatic purification goes on without interruption until the reagent
contained in the first cylinder is entirely exhausted.
The duration of this working varies from 2 to 6 days, according to the size of
the cylinders, the volume of water purified in the 24 hours, and the quantity of
calcareous salts contained in the water.
To empty the exhausted cylinder and to refill it with a fresh supply of the

page_text: purifying material prepared beforehand the flow of water is arrested for some
30 minutes. The position of the cocks is at the same time altered, the cock h
being opened to the right and the cock h² being opened to the left. The discharge
cock v is closed and v₁ is opened. By this means, on again allowing the water to
flow, it will begin by rising in the cylinder No. II., and by the tubes 1, 2, 3, will
reach the cylinder No. I through which it will pass, issuing by the discharge
cock into the pipe L.
The complete round or cycle of operations will thus have four combinations
for the four cylinders, viz., I., II., III., IV., II., III., IV., .I., III., IV., I., II.,
and IV., I., II., III.
The purifying material consists of a mixture of equal weights of magnesia (or a
magnesian composition which may be found in the earths containing magnesia)
and sifted sawdust derived from soft woods and free from small particles and
dust.
After having obtained a homogeneous mixture of these materials in a dry state
by means of a rotating drum, the hydration of the magnesia is to be effected by
adding gradually water to the extent of half the weight of the magnesia.
On working the mass hydrate of magnesia Mg 02 H³ is produced, which adheres
closely to the large surface presented to it by the fibres of the sawdust.
The mass dried in the air yields its surplus moisture, and a porous mass of the
nature of a coarse and hard powder results.
The adhesion of the hydrate of magnesia is remarkably strong. It cannot be
separated from the fibres of wood either by mechanical means or by washing.
This feature prevents the possibility of its fouling the cylinders, and renders it
certain that the magnesia shall not be carried off with the water, which moreover
rises with a minimum rapidity. This insoluble reagent possesses. the enormous
advantage of effecting by itself the progress of the purification. Water charged
with bicarbonates of lime and magnesia, as well as with sulphate of lime, if allowed
to remain during 15 minutes in contact with the large surface of the hydrate of
magnesia will be totally freed from calcareous salts.
A prompt and complete reaction takes place even at low temperatures.
The hydrate of magnesia by the absorption of the carbonic acid of the carbonates
is changed into neutral carbonate of magnesia, and precipitates the carbonate of
lime in the form of crystals of arragonite on the surface of the saw dust or
equivalent porous substance.
The neutral salt of carbonate of magnesia in its turn being soluble decomposes
the sulphate of lime, precipitating in a similar manner the carbonate of lime and
leaving the sulphate of magnesia in solution.
This last salt replaces therefore the gypsum, so dangerous as regards the incrus-
tation of steam boilers, while the sulphate of magnesia or bitter salt being very
-soluble-cannot-in-any case impregnate the water within the steam boilers to such
a degree of saturation as to form deposits therein.
It results from this that the effect of such an apparatus remains constant from
the beginning to the end, and that a large volume of water requires for its purifi-
cation cylinders of but relatively small dimension. The apparatus shewn on the
Drawing is capable of yielding during 12 hours as much as 50 cubic metres of
purified water.
By modifying the dimensions the apparatus may be arranged to yield from 8
to 420 cubic metres of water during the day of 24 hours.
As far as regards the spent condition, more or less complete, of the reagent,
practice has shewn that the loss occasioned by the recharging of the cylinder is
very small provided that the magnesian preparation is well ground to a fine
powder. This favourable fact is explained by the large proportion a volume of
sawdust bears in comparison with that of an equal weight of the magnesian
preparation.
Only 11th of the surface of the fibres are covered with magnesia, and the th
remain free for the deposit of the carbonate of lime.

page_text: Moreover the quantity of magnesia introduced into each cylinder being 6 times
more than is requisite to purify the largest quantity of water in 24 hours, it follows
that each cylinder in succession should be recharged every 6 days, and that the
complete round will take place in 24 days. Thus through each of the cylinders a
volume of water will have passed four times greater than that which corresponds
to the quantity of the reagent which it contains. This still further explains why
at the moment of recharging the cylinder the exhaustion of the reagent is almost
complete.
After having ascertained by means of a water index the maximum capacity of
the apparatus, and consequently the periods at which the cylinders must be
recharged, all further control is unnecessary, and the operation may be allowed to
continue without being dependent upon an attendant appointed for this duty.
By the use of this apparatus all the difficulties and inconveniences occasioned
by the employment of soluble reagents for dis-incrustation are entirely obviated.
A modification of this simple process is necessary when dealing with waters rich
in sulphate of lime and poor in carbonic acid.
In this case an analysis of the water shows once for all the amount of basic
carbonate of magnesia, 5 Mg O' CO³, which should be added in lieu of the oxide of
magnesium.
For waters rich in carbonic acid a caustic lime neutralizer should be used.
A determined quantity of lime water is blended with the non purified water
before it enters the first cylinder so as to absorb a great portion of the carbonic
acid. This effects an economy in the magnesia, and a smaller quantity of neutral
carbonate of magnesia remains in solution in the purified water.
This process
employed for the waters rich in carbonic acid offers the great advantage that it is
impossible for the caustic lime in case of excess to pass off in solution with the
purified water.
The presence of the basic magnesia 5 Mg O* CO² with Ca O produces two insoluble
salts Mg O and Ca CO,.
In these two cases the mode of working the apparatus remains precisely as
before.
Having now set forth the nature of the said Invention of "Improved Means for
Removing Calcareous and other Impurities from Water," as communicated to me
by my foreign correspondent, and having explained in what manner the same may
be carried into practical effect, I wish it to be understood that I claim,-
First. The purification of water charged with calcareous salts, such as the
bicarbonates of lime and magnesia, or sulphate of lime, by passing it in contact
with a filtering powder prepared from magnesia and sawdust or its equivalent,
substantially as described.
Second. The means, substantially as set forth, for purifying waters containing an
excess of either sulphate of line or carbonic acid.
Third. The construction and arrangement of apparatus, herein shewn and
described, whereby large volumes of water charged with calcareous and other
impurities may be purified by contact with a filtering medium, prepared as and .
for the purpose above set forth.
In witness whereof, I, the said Arthur William Lovell Reddie, bave hereunto
set my hand and seal, the Seventh day of March, in the year of our Lord
One thousand eight hundred and eighty two.
ARTHUR W. L. REDDIE. (L.S.)