A Purifying Apparatus for Steam Boilers.
Year: 1886

page_text: COMPLETE SPECIFICATION,
1
A Purifying Apparatus for Steam Boilers.
1 ALFRED DERVAUX of 47 Boulevard de Waterloo, Brussels in the Kingdom of
Belgium, Engineer, 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, reference being had to the accompanying
Drawing:
The apparatus placed at a higher level than that of the boiler is composed in
principle of a condenser C surmounting a receiver D placed in communication with
the boiler the first by a tube V extending to the lower part thereof and which is
provided with an opening P at the mean height of the water and the second by a
tube R extending simply into the water in the boiler.
In these conditions the air contained in the apparatus being drawn off or let out by
a small air cock X placed at the upper part of the apparatus the water in the boiler
under pressure fills the tubes V R and the apparatus CD when the opening P of the
tube is completely covered by water.
If the level of the water in the boiler is lowered and the opening P is uncovered
steam enters the tube V raises the water therein contained and forces it into the
boiler by the tube R at the same time with the water contained in the upper part of
the apparatus.
When the level of the water rises in the boiler the opening P becomes again
covered and the water rises anew into the apparatus CD by the tube V at first mixed
with the steam which rushes in by the opening P until this latter is completely
re-covered.
The apparatus empties and fills itself thus alternately with water which enters by
the tube to return to the boiler by the tube R according to the fluctuations in the

page_text: These fluctuations being continual and varying not only with the rate of feeding
but also with the heat of the furnace (marche du foyer) themselves induce (the
openings P being properly placed) a circulation almost continuous of the water to the
boiler through the apparatus the current ascending by the tube V and descending by
the tube R. The surface condenser C has in effect to condense (by simple cooling
due to the to the contact of the external air) the steam flowing with the water into
the apparatus by the extraction tube V.
But that is not the only cause of the circulation of the water from the boiler into
the apparatus. This circulation is maintained even when the opening P is completely
covered by the water and for the following reason.
In rising in the tube V the water from the boiler enters the tube necessarily in a
state of ebullition by reason of the pressure by which it is forced to rise above the
water level and it is kept in a state of ebullition by means of a tubular steam jacket E
in which the extraction tube V is enclosed and which envelopes it the whole of its
length.
Thus therefore is obtained in the tube V a column of water from the boiler in a
state of ebullition very light in consequence which passes into the condenser C.
There by radiation a slight cooling is produced which need not be even one degree to
stop the ebullition and there is formed in the apparatus CD and in the tube R a
column of water which while retaining the same temperature as that of the tube V
is much more dense because it is no longer in a state of ebullition. In these conditions
an active current of water from the boiler is produced by the apparatus CD ascending
by the tube V and descending by the tube R. The water of the boiler drawn in
from time to time in regulated quantities according to the relative dimensions of
the opening P from the bottom of the boiler where the calcareous mud remains and
from the surface where it swims in the state of froth. The water of the boiler rises
by the tube V into the condenser Ċ descends into the receiver D where it deposits
continually the matters which it holds in suspension by the fact of ebullition in the
boiler, (ebullition not occurring in the now heated apparatus CD) and returns to the
boiler by the tube R. The calcareous deposits thus accumulated in the receiver D are
withdrawn through the blow off cock F.
To prevent incrustation of the calcereous salts and to induce their precipitation (in
the state of mud) as they are extracted by the apparatus a suitable re-agent is
introduced into the boiler either by the water supply pump or by means of a funnel
placed on the suction pipe of the pump or by the receiver L. In the latter case by
means of a pipe B joined to the delivery pipe of the pump or of the injector there is
passed through the receiver L the feed water which draws the re-agent into the boiler
by the retaining valve A of the interior tube R¹.
The condenser C and the receiver D can be cast in one piece or made of sheet
metal and in a variety of forms. I give by way of example as is claimed elsewhere
to the condenser C the form of a cylinder with wings or ribs presenting a large
external radiating surface in a small compass with a small internal surface.
Instead of communicating with the boiler by means of a single tube V having an
opening at the water level and plunging into the lower parts so as to produce both
the extraction from the bottom and from the surface; the condenser C can be
connected to the boiler by means of two tubes the one reaching to the surface and
the other to the bottom and furnished or not with regulating valves, the same end is
thus obtained.
One can also cause in the tube V the formation of a mixed column of steam and
water which causes the circulation of the water of the boiler through the apparatus by
piercing in the steam chamber a small opening that can be furnished with a valve
forined for example of a simple screw with conical point which permits of the
admission of the steam for creating the current being regulated. This admission of
stoam even allows of the comparatively cold layers of water from the lower parts of
return flue boilers for example being raised to boiling point on their arrival at the
tube V and thus drawn in.

page_text: In certain boilers the calcareous mud tends to accumulate in a stagnant state in
the lower parts of the boiler which are only slightly heated.
As the apparatus cannot naturally extract the mud except it is in suspension on the
water I cause it to mix again with the water diluting it with the feed water which is
injected into the lower part of the boiler by means of the arrangement indicated in
dotted lines. The feed pipe It is prolonged horizontally along the lower part of the
boiler and is furnished with branches abc, the orifices of which point in the same
direction parallel to the surface to be cleared. By this arrangement the jet a spreading
out like a fan, cleans all the surface comprised between a and b the jet clears in the
same manner the stagnant mud from b to c and lastly the jet e disturbs the stagnant
mud between c and V. By the combined action of these jets directed in the same
plano all the surface of the boiler on which the mud tends to deposit in a stagnant
state is in some degree swept. By the action of each jet extending in the form of a
fan in a certain radius beyond which the action of the next jet commences the mud
thus put in suspension is easily extracted by the apparatus or expelled by a blow
off cock.
But in order that such an arrangement should be efficacious it is necessary
1st. That these jets be projected into the water and the mud, under a pressure much
exceeding the steam pressure of the boiler.
2nd. That they be sufficiently numerous to act simultaneously on the whole surface
(sometimes very extensive) where the deposition of the mud takes place.
3rd. That these jets should have an area sufficient to ensure a disturbing influence
on the water and the mud. On the other hand the orifices of injection should not
have a section too reduced in order that they may not become obstructed by
extraneous matters which may be in suspension in the feed water.
In general the force of the feed pumps regulated according to that of the boilers is
insufficient to feed the washing jets a be in sufficient number of suitable section and
under a pressure sufficient to accomplish the desired result.
Recourse is therefore had to the following arrangement.--
The retaining valve A becomes an accumulating valve represented in Figs. 2 and 3,
and the receiver L becomes an accumulating receiver for compressed air. The valve A
is loaded either by means of a spring or by means of a direct weight p.
The seat of a valve of larger diameter only bears on a small section say 2 mm for
example around its orifice the remainder of its surface is hollowed out and does
not bear.
Here then is how it operates.
A small air cock placed on the suction pipe of the pump is opened. This delivers
air into the receiver L.
When it is judged that this is full of air, the air cock is closed and the pump forces
the feed water into the receiver. What then takes place ?
The air contained in the receiver is compressed and as long as the pressure in the
receiver exerting itself from below to above on the part of the valve covering the
orifice s has not become equal to the pressure of the boiler plus that of the weight p
exerting itself in the contrary direction on the valve, the valve remains closed. As
soon as the pressure in the receiver exceeds the sum of the pressures above mentioned
which maintain the valve on its seat, the valve rises. From this moment the pressure
of the compressed air in the receiver L no longer exerts itself only on the small
surface corresponding to the openings of the valve but on all the larger surface S
which covered the seat.
On the rise of the valve the water accumulated in the receiver is forced into the
boiler by the elastic pressure of the confined air until equilibrium is established between
the pressure of the air on the receiver L and that of the boiler plus the weight p of
the valve. So soon as equilibrium is reestablished the valve drops on to its seat.
The result is this the strokes of the pump accumulate in the receiver L, and are
paid out in a single iet from the moment when the valve rises to the moment when
it falls,

page_text: s surface of the orifice of the valve.
S surface of the large seat of the valve.
-
The equation of equilibrium for the opening of the valve is (1) Cs = ns + p.
The equation of equilibrium for the closing of the valve is (2) c S= n S + p.
Let S 18 squares = 3" = 5 kilos c=
10 kilos we shall have
(1) 10 x 3 =
=5x+p of which p 15 kilos so that the valve does not rise
except at the pressure of 10 kilos per square "/m
We shall have then
(2) x 18
-
=
5 × 18+ 15 = 105 that is to say c
square under which the valve returns to its seat.
=
105
1.8
5.833 kilos pressure per
The object of hollowing out of the valve from the surface of contact around its
orifice is to provide a clearance for leaks occurring on this surface. Now suppose a
feed pump giving 0.2 litres per stroke of the piston and a delivery receiver with a
capacity for example of 40 litres.
The pump is set to work with the air cock on the suction pipe open.
When it is thought the receiver is full of air after a certain time the air cock is
closed and the pump forces the water into the receiver, the air in which is compressed
up to a pressure of 10 kilos per square /m as in our example.
At this moment the valve will rise and will allow the water to flow towards the
boiler and eventually the air until the pressure in the receiver has fallen from 10 kilos
to 5.833 kilos-The valve then falls onto its seat and the water will accumulate anew
(by the forcing of the pump) in the receiver L until the air therein contained he again
compressed to 10 kilos.
Under these conditions if the receiver has been well filled with air when the pressure
therein passes from 5.833 to 10 the volume of air in the receiver will be contracted in
the relation of 5-833.10 that is to say there will be in the receiver
1
5.883
=
× 40
23.3 litres of compressed air at 10 and 40 - 23.3 16.7 litres of
1.0
water which will pass in a single jet into the boiler with a decreasing pressure of 10 to
5.833-There will be accumulated in the receiver
16.7
0-2
83.5 strokes of the pump
which will be given out in a single jet by the washing orifices..
The preceeding calculations are evidently only approximate but they demonstrate
sufficiently that one will obtain as required the accumulation of a large number of
strokes of the pump for the service of the washing orifices.
The Giffard injector, by means of which air can be easily forced in, and which is
capable of delivering under a pressure much greater than the boiler is able to do, may
although in a less degree but quite sufficient, be used for the washing.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is :-
1st. The general arrangement of the apparatus and its connection with the boiler
by means of pipes as described permitting of the simultaneous extraction from the
bottom and from the surface of the water in the boiler of the sedementary matters
contained in the water.

page_text: 2nd. The admission of steam to the extraction pipe of the apparatus such admission
being automatically regulated as described.
3rd. The application of a steam jacket to the said extraction pipe for the purpose
set forth.
4th. The employment of a condenser C with transverse or longitudinal ribs or wings
which augment the external radiating surface.
5th. Stirring the stagnant mud or deposit by the combined action of the jets of
feed water arranged with respect to each other as above described.
6th. The arrangement described for the accumulation within a receiver fitted with a
retaining valve of water by means of a large number of strokes of the water supply
pump for the periodical delivery of a single jet through the washing orifices.
Dated this 30th day of December 1886.
NEWTON & SON,
Agents for the Applicant.