Improvements in Steam Generating Apparatus, commonly called Water Tube Boilers, and Means of Causing Circulation therein.
Year: 1898

page_text: Improvements in Steam Generating Apparatus, commonly called
Water Tube Boilers, and Means of Causing Circulation therein.
I. CHARLES ARTHUR ALLISON, of 52, Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by John Clinton Parker of the City
and County of San Francisco, State of California, United States of America) to
be as follows:-
My invention consists in providing automatic check valves in the water tubes
or their connections in what may be called the downtake pipes or conduits lead-
ing from below the water level in a superimposed vessel or steam drum, and con-
necting to the evaporating tubes anterior to their exposure to the hottest fire or
highest temperature in a furnace; such check valves being placed at or near the
superimposed vessel or steam drum and closing toward the same, and also at the
induction or receiving ends of the evaporating tubes, whereby circulation is so
directed that the temperature of the water, or water and steam, in the evaporat-
ing tubes and the temperature of the hot gases in the furnace are assimilated,
relatively, so that heating and evaporation of the water is progressive and cumu-
lative from the coolest to the hottest portion of the furnace; the check or non-
return valves, which can be of any of the well known forms, permitting flow in
one direction only.
Dated thig 3rd day of March 1808
ALLISON BROS.,
Agents for the Applicant.
Improvements in Steam Generating Apparatus, commonly called
Water Tube Boilers, and Means of Causing Circulation therein.
I, CHARLES ARTHUR ALLISON, of 52, Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
D

page_text: has been communicated to me from abroad by John Clinton Parker of the City
and County of San Francisco, State of California, 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:-
My invention relates to certain improvements in steam generators of the type
commonly called water tube boilers, wherein the water to be converted to steam
is contained and circulated in tubular folds or coils exposed to the heat of a fur-
nace, and to a novel manner of directing and controlling such circulation or flow.
My improvement consists in a set or system of evaporating tubes disposed in
coils or otherwise to attain the required length in a limited space; one end of
the evaporating tubes communicating with the water space of a superimposed
vessel or drum and the other end of these evaporating tubes communicating with
the steam space in the superimposed vessel, so the water is free to flow from the
water space, downwards towards the fire and from the coolest to the hottest por-
tion of the tubes, but not to return, a check valve or valves being provided to
prevent flow of the circulated water in the opposite and usual direction upward
and from the hottest to the coolest portion of the furnace.
To
The objects of my invention are primarily to attain progressive heating and
evaporation of the water by an assimilation of the temperature of the furnace and
the water, the latter flowing from the lowest to the highest temperature,
reversely to the usual course of circulation in tubulous steam generators.
attain in fullest degree possible the transfer of heat to the water. To produce a
rate of circulation or supply of water that corresponds to and is determinable by
the rate of evaporation, preventing circulation of water to or through the steam
space, and other objects that will be hereinafter more fully pointed out and
explained in connection with the drawing herewith, illustrating a manner of.
applying my improvements in practice.
Fig. 1 represents a longitudinal section through a steam generator and furnace
for the same, operating according to my invention.
Fig. 2 is an end view, partially in section, of the same steam generator and
furnace, the furnace front covering being removed.
The furnace 1 is of the usual construction provided with a metallic front 2,
grates 3 and a chimney 4.
The steam generator or boiler consists in the present case of the following
elements; A steam drum 5, partially filled with water and set at the top of the s
furnace; a series of evaporating tubes 6, 7, 8 and 9, preferably set in a hori
zontal position;-inclined evaporating tubes 10, an uptake pipe 11 for steam, the
return or junction chamber 12, front junction chambers 13 and the check or non-
return valves 14.
This construction I have assumed as one suitable to illustrate my invention
which is not, however, confined to any particular form of tubulous generators,
but is applicable to all, wherein the water circulates and steam is generated within
the tubes or coils.
4
The steam drum 5 is partially filled with water as indicated in Fig. 1. When
the water in the tubes 10 is evaporated and rises through the uptake pipe 11, 4
water descends through the automatic check valves 14 to replace what is
evaporated. This valve opens outward from the steam drum 5 permitting the
water to enter the upper evaporating tubes 6 from where it passes successively
through the other pairs of tubes 7, 8, 9 and 10 as indicated by the arrows, and
after evaporation in the lower tubes 8, 9 and 10, passes as steam up the tubes 11 5
to the space in the drum 5.
The temperature in the evaporating tubes and furnace is indicated approxi-
mately by the Fahrenheit scale of degrees marked in figures thereon, so it will
be seen how the water is progressively heated, entering first the tubes 6 at the
top having the lowest temperature and moving continually towards the hottest 5
tubes and highest temperature in the furnace, and in a direction the reverse of

page_text: common practice in steam generators of this type; also that the steam generated
flows from the hottest evaporating surfaces directly to the steam-drum without
passing through or being impeded by the water.
In a steam generator arranged as shown and at ordinary pressure evaporation
will begin in the tubes 8, as indicated in the drawing, and be completed in the
lower and hottest tubes 10 from which, as before explained, the steam passes to
the drum 5, through the pipes 11 one for each vertical tier of evaporating tubes,
or these pipes 11 can be combined and two or more tiers of evaporating tubes be
connected to each uptake pipe by means of the junction chambers 16.
The check or non-return valves 14 and the results attained thereby constitute
an essential feature of my invention because without these valves circulation
would start the other way against the least hydrostatic head and steam would
find its way back through the water in the tubes 6, 7, 8 and 9. The valves 14
may be constructively of any of the well known forms that permit free flow in
one direction only, preferably to close by their gravity, and when provided with
external means of adjustment, as by the screws 15, can be employed to regulate
the amount of water passing to the evaporating tubes, and consequently the
dryness of the steam passing up the pipes 11.
In the manner of operating herein described there is the distinction from
common practice that the heat is mainly applied to the water as it descends or
approaches the hottest portion of the furnace and the water is supplied as fast only
as it is evaporated and does not circulate or pass back to the steam drum. The
steam when generated leaves the evaporating surfaces at the hottest portion
thereof, instead of the higher and cooler portion and in rising does not pass
through water. In other words the usual course of circulation is reversed.
In the case of obstruction or resistance from any cause to the circulation of
the water in the direction indicated, the valves 14 close instantly and circulation
is forced by the expansion of the steam generated in the evaporating tubes 6, 7,
8, 9 and 10.
When the water is all evaporated before it leaves the tubes 10, which is the
normal condition of operating, circulation is impelled by the whole gravity head of
the water from the level in the steam drum 5 down to the lower evaporating
tubes, sufficient to produce a very rapid flow, but if the amount of water descend-
ing exceeds what is being evaporated, the gravity head and the rate of circula-
tion are reduced accordingly by the water rising in the pipes 11 so that circula-
tion is in this manner automatically controlled; also can be regulated by the
valves 14, as before explained.
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:―
1. In a steam generator of the water tube type, a superimposed vessel or
vessels having water and steam spaces, folds or coils of generating tubes extend-
ing downward from the water space toward the fire and from the coolest to the
hottest part of the furnace, and thence by continuous connection to the steam
space above, check valves in these tubes at or near the water space automatically
opening outward therefrom, preventing circulation backward to the water space
and supplying water in proportion to evaporation in the lowest and hottest tubes.
2. In a steam generator of the water tube type, a continuous passage for water
and steam from a superimposed water space to a superimposed steam space advanc-
ing through the heating furnace from the coolest to the hottest portion thereof:
check valves to admit water to this passage as rapidly as the water is converted
to steam and as the hydrostatic heads may cause a flow thereof downwards towards
the fire.
3. In a steam generator of the water tube type, superimposed steam and water
spaces, down-flowing tubes from the latter and up-flowing tubes to the steam

page_text: space, forming a continuous passage through the furnace from the coolest to the
hottest part thereof, and adapted for complete evaporation of the water in the
lowest and hottest portion of the tubes, producing a hydrostatic head to impel
the water downward from the superimposed water space and check valves to pre-
vent backward flow of water or steam to the water space.
Dated this 5th day of December 1898.
ALLISON BROS.,
Agents for the Applicant.