IMPROVEMENTS IN HEATING APPARATUS
Year: 1884

page_text: "
I ALFRED JULIUS BOULT. of 323 High Holborn in the county of Middlesex,
Engineer do hereby declare the nature of this invention for "IMPROVEMENTS IN
HEATING APPARATUS (a communication from Edward Ethel Gold of the city of
New York, United States of America) and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
This invention relates more particularly to that class of steam heating apparatus
in which the heat of steam is applied to an enclosed mass of water or other heat
absorbing material which will act as a reservoir so to speak for the heat so that the
said reservoir need to be charged with heat only at certain intervals and will con-
tinue to give it out slowly for some time afterwards.
Heaters of this class are particularly well adapted for passenger cars, as steam
requires to be applied to the heaters only at certain intervals or say at the ends of
the trips only, at which times the water in the heaters may be raised to a high tem-
perature and thus charged with a great quantity of heat which will be gradually
radiated during the next trip.
In a former patent of the United States issued February 14th 1882 N° 253693 a
heater of this class is shown consisting of a cylinder of cast iron having a partition
which divides the cylinder into an upper chamber which is charged with water and
a lower chamber to receive the steam to heat said liquid.
Now the present invention is an important improvement on that type of heater,
and in this case the heater is formed of two distinct vessels or cylinders, one placed
directly within the other the inner vessel being preferably charged with the liquid
while the outer vessel which completely encloses it receives the steam which
envelopes and heats the liquid and from which the heat is subsequently radiated
through the walls of both vessels.
This system has the advantage of being very simple and inexpensive in con-
struction and may be made of simple wrought pipe and fittings, and is thus at once
light and strong and impervious to leakages and not affected by contractions or
expansion, and at the same time possesses great absorbing and radiating qualities,

page_text: and this invention therefore consists chiefly in the features here outlined as
hereinafter fully set forth.
4
In the drawings annexed, Figure 1. presents a longitudinal elevation of one of the
improved heaters. Figure 2. is a longitudinal section of the same and Figure 3. a
cross section thereof Figure 4. is a cross section of a modification.
Referring to the drawings a indicates the outer vessel or chamber of the heater
and b the inner vessel, each of which are distinct enclosures and which are preferably
made of wrought tubing preferably "boiler tubes."
The ends of the inner tube b are preferably closed by wrought iron heads welded
therein, and this tube before it is placed in the outer tube is charged through a hole
in one end with saturated salt water to about seven eighths full leaving a small air
space, as shown, to allow for expansion, and the hole is afterwards plugged by the
screw plug e thus hermetically sealing the liquid in the tube.
The ends of the outer tube a are closed after the inner tube is placed therein,
preferably by cast-iron heads d d screwed thereon as best shown in Figure 2 and
near the lower edge of said heads screw-holes are formed to connect with steam-
pipes as shewn whereby steam may be admitted to the outer vessel to envelope the
inner vessel as will be understood.
For practical car-heating it is preferable to make the outer tube four inches in
diameter and the inner tube three inches in diameter the inner tube being thus
about an inch smaller than the outer tube and also a little shorter in length than
the outer tube so that the inner tube fits within the outer tube without touching
the ends, thus leaving free room for expansion. The inner tube is also preferably
placed eccentrically in the outer tube so as to be in contact with each other at the
top, the inner tube being supported at the bottom on a piece of iron pipe or rod i
placed between the bottom of the inner and outer pipes as best shown in Figure 3.
A steam space is thus formed almost all round the inner pipe, the space being in
this case of crescent shape so that the steam when admitted to the outer vessel will
envelope the inner pipe which will thus present almost its entire surface for con-
densation of the steam and absorption of the heat, which feature forms one point of
this invention without regard to the special construction of the chambers them-
selves.
The result therefore will be that when the steam is admitted to the outer tube it
will be condensed rapidly on the inner tube and its heat thus rapidly absorbed by
the inner tube and the liquid within it, which in a few minutes will be raised to
nearly the temperature of the steam, and in so doing will absorb a vast quantity of
heat which after the flow of steam is cut off will be retained for a long time and
gradually radiated through the walls of both vessels into the car or other apartment
in which the heater may be placed.
Hence by this means when the heaters are used in railway cars and connected
with the engine steam need only be admitted to the outer tubes at intervals during
the run and the heat will be stored up in the liquid reservoirs and thus given out
regularly thereafter or if the heaters are used in street cars the heaters need only be
connected for a few minutes with a stationery steam boiler at one or both ends of
the route until the liquid reservoirs are heated to the desired temperature when the
heat thus absorbed will last during the next trip, as will be readily understood, thus
presenting great advantages for such purposes.
The tubes of the heaters may be made of any desired length, and in case of Street
cars but one heater may be used on each side running the entire length of the car,
as the boiler tubes may be obtained in continuous lengths suited for this purpose
which is one of the prominent constructive advantages of this plan. In some cases,
however, the tubes may be cast in short lengths to form short heaters, and a series
of these may be placed in successive order and' connected together by short steam
pipes g extending from head to head, as will be understood, the outer tubes being
properly supported and raised up from the car floor on chairs h, see Fig. 1, of the
usual character, as will be readily comprehended.
ન

page_text: It will be seen that as the inner tube is entirely distinct from the outer tube and
is simply enclosed in the outer tube and free therein, and both made of wrought
pipe, hence the construction is not only very light simple and inexpensive, but the
two tubes are left entirely free to expand or contract and hence cannot become
strained warped or leaky by changes of temperature as would be likely to occur
where tubes are connected rigidly together Another advantage of having the inner
tube of wrought metal is that it is thereby rendered much more impervious to the
salt water than would be the case with cast iron, and is, at the same time a better
conductor of heat. If desired, however, both tubes may be of cast metal, or the
inner tube may be wrought and the outer tube cast.
If desired also the inner tube and outer tube might be cast together, the inner tube
in an eccentric position, leaving a crescent-shaped or nearly encircling steam-space
hetween the two, as seen in Fig 3, as this forms one of the advantages of the present
arrangement, but I consider the exact construction illustrated preferable.
Instead of having one liquid tube within the outer steam tube, the steam tube
might be packed with a series of small liquid tubes, leaving spaces between the same
through which the steam would pass, as shown in Fig. 4. Or again, instead of
having one round liquid tube placed eccentrically, the inner tube might be placed
centrally, and instead of having two points of metallic contact between the tubes,
as in Fig. 3, they may be made to contact metallically at numerous points around
the circumference so as to ensure more rapid conduction of heat from the inner to
the outer tube, as will be understood. Furthermore instead of having the inner tube
round it may be corrugated, the crests of the corrugations fitting the interior of the
outer tube.
Referring to Fig. 3. it will be noted that instead of supporting the inner tube on
the small pipe or rod it may be supported on screw-plugs f screwed through the
outer tube, or collars may be slipped on the inner tube at numerous points so as to
fit to, and rest on, the inner tube. It is obvious, however that various other slight
modifications may be adopted without departing from the essential features of the
plan here shown.
The water used in the inner tubes may be charged with any other substance
besides salt to prevent freezing, or if preferred some other material besides water
may be used for example, acetate of soda, or even sand may be used, but water is of
course obviously preferable on account of its cheapness and the fact that it absorbs
a greater quantity of heat than any other substance.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed, I declare that
what I claim is
1st An improved heater formed of two distinct tubes or vessels, one placed within
the other, the inner one being charged with water or its equivalent, and the outer
being adapted to receive steam or other heating fluid, substantially as and for the
purpose set forth.
2nd An improved heater formed of an outer heating tube provided with con-
nections for admission of steam, in combination with a distinct inner tube charged
with liquid or its equivalent and sealed and placed loosely within the outer tube,
enclosed thereby and free to expand or contract in said enclosing tube, substantially
as herein shown and described.
3rd A heater formed of two chambers or vessels one within the other, the outer
one being adapted to receive steam or other heating fluid, and the inner vessel being
sealed and charged with water or its equivalent, and placed within the outer vessel
in such position as to leave a circumferential steam or heating space between the
two circumscribing the inner vessel, substantially as and for the purpose set forth.
4th An improved heater formed of an outer steam tube and an inner tube charged
with liquid, or its equivalent placed within the outer tube in an eccentric position,
substantially as herein shown and described.

page_text: 5th The outer tube a provided with screw-heads d and connections for admission
of steam in combination with the inner sealed tube charged with water or its
equivalent.
Gth A heater formed of two wrought metal pipes placed one within the other, the
end of the outer pipe being closed and adapted to connect with a supply of steam,
while the inner pipe is charged with a mass of water, or its equivalent, and sealed
and placed loosely in the outer pipe, substantially as herein shown and described.
7th The combination with the inner sealed pipe b with welded heads, of the outer
pipe a with its screw heads d d and connections for steam supply, substantially as
and for the purpose set forth