Improvements in Feed-water Heaters.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Feed-water Heaters.
1, WILHELM SCHMIDT, of Ballenstedt on the Harz, in the Duchy of Anhalt,
German Empire, Civil Engineer, do hereby declare the nature of this invention to
be as follows :-
'
It is known that to exhaust the waste gases of a steam boiler furnace by letting
them heat the feed water large surfaces are requisite if that exhaust is to be a
somewhat considerable one. Said large surfaces necessitate generally a great space
which is tolerably reduced only if the feed water heater is formed by coiled pipes.
There is, however, then created another drawback that consists in the clogging of
said pipes by incrustated sediments; these latter before causing the final clogging
of the pipes hinder them from properly transmitting the heat of the waste
gases upon the feed-water, and the exhaust of said gases is, therefore, an
unsatisfactory one.
The object of my invention is to overcome all the said drawbacks, and I attain
that object in general by enclosing a certain quantity of pure water within a coil
one part of which is acted on by the waste gases of a boiler furnace, whereas the
other part acts in its turn upon the feed-water. The end of said coil is connected
with the commencement of the same, or vice versa, and the pure water that
circulates quickly, or is artificially caused quickly to circulate, through and within
the coil receives the heat of the waste-gases, and transmits it to the feed-water.
The heat of the waste-gases is thus taken up by a coil or coils, but there is no
possibility of the latter getting clogged, as the water circulating within that coils
has originally been introduced in a pure state, and remains so.
In order to make my invention more clear, I refer to the accompanying
drawings, in which similar letters denote similar parts throughout the different
views, and in which ;-
Figure 1 is a vertical longitudinal section through the rear portion of a Cornwall
boiler that is furnished with my novel arrangement,
Figure 2 shows said arrangement combined with an upright boiler of a particular
construction, and
Figure 3 is a horizontal section taken on line 4-5 of Figure 1.
The transmission of the heat upon the feed-water takes place within the feed-
water heater a (Figs. 1 & 2) that contains the cylindrical coil b; the latter is filled
with pure water which flows, as a matter of course, in a downward direction,
whereas the feed water enters the vessel a at the bottom thereof, and leaves it in a
heated state at the top. It is obvious that by this means the feed water is highly
heated, whereas the pure water is correspondingly cooled; the latter when leaving
the coil b passes into the coils &¹ (Figs. 1 & 2) that are arranged in the way of the
fire-gases streaming forth from the furnace of the respective boiler. Said coils 6¹
offer the last surfaces that can usefully consume the heat of the escaping fire-gases,
and said heat is transmitted to the pure water, that comes down from the cylindrical
coil b, passes through the coils 6', and flows again up to said cylindrical coil b. The
coils bb form a continuous way, and may practically be regarded as one serpent
consisting of two parts. In either of said parts the direction of motion of the
respective two media is one opposite to the other.
In the form of construction represented in Figs. 1 & 3, I have shown my novel
arrangement combined with a flame-tube boiler that is furnished with a throttle-

page_text: valve R, or other equivalent device, for regulating the temperature as well as the
quantity of the fire-gases flowing from the flame-tube into the vaulted chamber K.
The latter forms a part of the conduit that leads the waste gases to the chimney.
The heat of said gases is taken up in two stages, in that the said gases are first
caused to wash a superheater S that consists of coiled pipes, and is arranged above
the coils afore mentioned. The size of said superheater is, as a matter of course,
chosen so as to superheat the steam of the boiler up to the desired degree.
The coils (that contain the pure water for transmitting the remainder of the
heat of the waste gases upon the feed water within the vessel a) are thus washed by
the waste gases only after these latter have acted upon the superheater S. Owing
to the greatly reduced temperature of said gases when arriving at the coils 6, the
water within the latter can never get exposed to a stronger pressure than the boiler
water proper, and I am thus enabled to connect the coils b'b' with the steam-space
of the boiler by means of a pipe g. The purpose of this connection is to allow of
the steam. replacing that part of the pure water contained within said coils b 6' that
has got lost by leakage and the like. Other devices for filling in such a case the
coils bb up may thus entirely be dispensed with.
Instead of letting the pure water when passing through the coils 6 run fully in a
direction opposite to that of the waste gases, I may in some cases lead it partly in
.said latter direction, and partly in a direction opposite to the former, or equal to
that of the waste-gases respectively. Such a modification of the method is
necessary in all boilers in which the waste-gases flow in an upward direction, as is
especially the case with upright boilers.
In the correspondingly modified arrangement shown in Fig. 2, the pure water
coming from the feed-water heater a passes through the coils 6' in a downward
direction, ie, opposite to the direction of the furnace gases; the number and length
.. of said: coils is so chosen that the water cannot be turned into steam. The water is
then led by the mediation of a pipe 62 into the lowermost of a number of coils 63
arranged below the coils 6'. Said coils 63 are exposed to far hotter gases than the
coils, and a part of the hot water flowing through the coils 63 is, therefore, turned
ipto steam. The mixture of hot water and steam flows finally upwards through the
pipe f.
By these means I not only gain the difference in weight between the hot water
and the cooled water as a motive power for causing the water to circulate through
the coils, as in Figs. 1 & 3, but moreover I increase that effect by letting a part of
the water be turned into steam so as to obtain a still greater difference in weight, as
r.in Fig. 2. The fast circulation of the water is very advantageous if the temperature
of the waste-gases is a somewhat high one.
The.water and steam separate when escaping from the upper end of the pipe fi
the water is collected by a vessel e, and led off by a pipe d to the connecting-pipe 62
afore mentioned; the steam enters the cylindrical coil 6 within the feed water
heater a, and condenses again. to pure water whilst giving its heat off to the feed
water. Said water then passes into the coils 6', and the circuit afore described
..commences.anew. The fact that the speed of the water when flowing through the
coils 6 is considerably lower than when flowing through the coils 63 affords two
important advantages. First, by the. slow speed of the water within the coils
the heat of the waste-guses is very thoroughly consumed; second, by the fast speed
of the water within the coils 63 the latter are very effectively prevented from being
burnt.
The water collected. within the vessel e need not all be led off into the pipe 62, or
the coils 63 respectively, but the quantity of the water led over into said parts'b 2
or 3 may be regulated according to the temperature of the fire-gases, preferably
by a cock H or other equivalent means. Owing to the insertion of the vessel e
between the coils 6.3 and b'the passage of the steam, from the pipe to the coil b
occurs free of shocks. Said vessel. may, if desired, be furnished with a 'gauge-cock
.or gauge-glass, as well as with a-funnel or otlier device for filling fresh pure water
into the apparatus if a part of the previous water has got lost by leakage or the like.

page_text: Said cock and funnel or equivalent parts may, as a matter of course, be arranged
also at other suitable parts of the apparatus.
Also in the modified construction shown in Fig: 2 the coils 6' 63 may be combined'
with a superheater; the latter may be arranged either below said coils (or, in other
words, in front of the same with regard to the direction of the fire-gases, as in Fig. 1).
or between the set of coils b' and the set of coils 63, but other arrangements may as
well be chosen.
Dated this 22nd of Ji
WILHELM SCHMIDT,
By Cassell & Co.,...
22 Glasshouse Street, Regent Street, London,
Agents for the Applicant.
I, WILHELM SCHMIDT, of Ballenstedt on the "Harz; in the Duchy of
Anhalt, German Empire, Civil 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:-
It is known that to exhaust the waste gases of a steam boiler furnace by letting
them heat the feed water large surfaces are requisite if that exhaust is to be a
somewhat considerable one. Said large surfaces necessitate generally a great
space which is tolerably reduced only if the feed water heater is formed by coiled
pipes. There is, however, then created another drawback that consists in the
clogging of said pipes by incrustated sediments; these latter' before" causing the'
final clogging of the pipes hinder them from properly transmitting the heat of
the waste gases to the feed water, and the exhaust of said gases is, therefore, 'an
unsatisfactory one.
11 4
The object of my invention is to overcome all the said drawbacks, and I attain
that object in general by enclosing a certain quantity of pure water within a coil
one part of which is acted on by the waste gases of a boiler furnace, whereas the
other part acts in its turn upon the feed-water. The end of said coil is connected"
with the commencement of the same, or tice versa, 'and' the pure water t
circulates quickly, or is artificially caused quickly to circulate, through and
within the coil receives the heat of the waste-gases, and transmits it to the feed-""
water. The heat of the waste-gases is thus taken up by a coil or coils, but there is"
within' that"
no possibility of the latter getting clogged, as the water circulating
coil bas originally been introduced in a pure state, and remains
In order to make my invention more clear, I refer to the drawings sent in with
provisional application, in which similar letters denote similar parts throughout the
different views, and in which:
Figure is a vertical longitudinal section through the rear portion of a
Cornwall boiler that is furnished with my novel arrangement,
Figure 2 shows said arrangement combined with an upright boiler of a particular..
construction, and
Figure 3 is a horizontal 'section taken on line 4-5 of Figure 1.
1.
The transmission of the heat to the feed-water 'takes place within the feed-water
heater 'a (Figs. 1 & 2) that contains the cylindrical coil the latter is filled with
pure water which flows, as a matter of course, in a downward direction, whereas
the feed water enters the vessel a at the bottom thereof, and leaves it in a heated
state at the top. It is obvious that by this means the feed water is highly heated
whereas. the pure water is correspondingly cooled; the latter when leaving the "
1

page_text: coil b passes into the coils b (Figs. 1 & 2) that are arranged in the way of the
fire-gases streaming forth from the furnace of the respective boiler. Said coils b¹
offer the last surfaces that can usefully consume the heat of the escaping fire-gases,
and said heat is transmitted to the pure water, that comes down from the
cylindrical coil b, passes through the coils b', and flows again up to said cylindrical
coil b. The coils & form a continuous way, and may practically be regarded as
one serpent consisting of two parts. In either of said parts the direction of
motion of the respective two media is one opposite to the other.
In the form of construction represented in Figs. 1 and 3, I have shown my novel
arrangement combined with a flame-tube boiler that is furnished with a throttle-
valve R, or other equivalent device, for regulating the temperature as well as the
quantity of the fire-gases flowing from the flame-tube into the vaulted chamber K.
The latter forms a part of the conduit that leads the waste gases to the chimney.
The heat of said gases is taken up in two stages, in that the said gases are first
caused to come into contact with or pass over a superheater S that consists of
coiled pipes, and is arranged above the coils & afore mentioned. The size of said
superheater is, as a matter of course, chosen so as to superheat the steam of the
boiler up to the desired degree.
The coils 6 (that contain the pure water for transmitting the remainder of the
heat of the waste gases upon the feed water within the vessel a) are thus heated
by the waste gases only after these latter have acted upon the superheater S.
Owing to the greatly reduced temperature of said gases when arriving at the
coils 6, the water within the latter can never get exposed to a stronger pressure
than the boiler water proper, and I am thus enabled to connect the coils bbl with
the steam-space of the boiler by means of a pipe g. The purpose of this
connection is to allow of the steam replacing that part of the pure water contained
within said coils bb' that has got lost by leakage and the like. Other devices for
filling in such a case the coils bb' may thus entirely be dispensed with.
Instead of letting the pure water when passing through the coils b¹ run fully in
a direction opposite to that of the waste gases, I may in some cases lead it partly
in said latter direction, and partly in a direction opposite to the former, or equal to
that of the waste-gases respectively. Such a modification of the method is
necessary in all boilers in which the waste-gases flow in an upward direction, as is
especially with upright boilers the case.
In the correspondingly modified arrangement shown in Fig. 2, the pure water
coming from the feed-water heater a passes through the coils 6 in a downward
direction, i.e. opposite to the direction of the furnace gases; the number and
length of said coils is so chosen that the water cannot be turned into steam. The
water is then led by the mediation of a pipe 62 into the lowermost of a number of
coils 63 arranged below the coils 6. Said coils 63 are exposed to far hotter gases
than the coils b', and a part of the hot water flowing through the coils 63 is,
therefore, turned into steam. The mixture of hot water and steam flows finally
upwards through the pipe f.
By these means I not only gain the difference in weight between the hot water
and the cooled water as a motive power for causing the water to circulate through
the coils, as in Figs. 1 & 3, but moreover I increase that effect by letting a part of the
water be turned into steam so as to obtain a still greater difference in weight, as in
Fig. 2. The fast circulation of the water is very advantageous if the temperature
of the waste-gases is a somewhat high one.
The water and steam separate when escaping from the upper end of the pipef;
the water is collected by a vessel e, and 'led off by a pipe d to the connecting-
pipe 62 afore mentioned the steam enters the cylindrical coil within the feed
water heater a, and condenses again to pure water whilst giving its heat off to the
feed water. Said water then passes into the coils b', and the circuit afore described
commences anew. The fact that the speed of the water when flowing through the
coils is considerably lower than when flowing through the coils 63 affords two
important advantages. First, by the slow speed of the water within the coils &

page_text: the heat of the waste-gases is very thoroughly consumed; second, by the fast.
speed of the water within the coils 63 the latter are very effectively prevented
from being burnt.
The water collected within the vessel e need not all be led off into the pipe 62,
or the coils 63 respectively, but the quantity of the water led over into said
parts 62 or 63 may be regulated according to the temperature of the fire-gases,
preferably by a cock H or other equivalent means. Owing to the insertion of the
vessel e between the coils 63 and b the passage of the steam from the pipe fto.
the coil b occurs free of shocks. Said vessel may, if desired, be furnished with a
gauge-cock or gauge-glass, as well as with a funnel or other device for filling fresh
pure water into the apparatus if a part of the previous water has got lost by
feakage or the like. Said cock and funnel or equivalent parts may, as a matter of
course, be arranged also at other suitable parts of the apparatus.
Also in the modified construction shown in Fig. 2 the coils 6' 63 may be combined
with a superheater; the latter may be arranged either below said coils (or, in other
words, in front of the same with regard to the direction of the fire gases, as in
Fig. 1) or between the set of coils b' and the set of coils b3, but other arrangements
may as well be chosen.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same' is to be performed, I declare that what I
claim is :-
1. A feed water heater for steam boilers, characterized by the heating of the
feed-water being effected by means of one and the same quantity of pure,.
constantly circulating water, which is heated within a serpent-pipe arranged
within the way of the waste-gases of the boiler, and which on its way back to.
said serpent-pipe passes through the feed-water container, for the purpose as
described
2. In a feed water heater of the kind characterized by Claim 1, the connection.
of the serpent-pipe containing the water serving as a heating-medium with the
steam-space of the boiler, for the purpose as described.
Dated this 14th day of October 1896.
WILHELM SCHMIDT,
By Cassell & Co.,
22 Glasshouse Street, Regent Street, London,.
Agents for the Applicant.