Improvements in Steam Generators.
Year: 1899

page_text: Date of Application, 30th June, 1899-Accepted, 7th Oct., 1839
COMPLETE SPECIFICATION.
Improvements in Steam Generators.
I, JOHN CLINTON PARKER, of 22, California Street, in the City of San Fran-
cisco, State of California, United States of America, 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:―
My invention relates to steam generating apparatus and to certain improve-
ments therein, especially applicable to the water tube type of generators.
My improvements consist essentially in so constructing and arranging the
heating and evaporating tubes of such generators that the areas of their cross
sections will be in proportion to the volumes and velocities of the water and
steam and in keeping water and steam separate as far as possible throughout the
cycle of circulation. It also consists in separate superimposed chambers for
steam and water, also in check valves to prevent the flow of water except in
the intended direction.
The objects of my invention are to attain a more effective, safe and economical
operation of water tube steam generators by maintaining constantly the full
gravity head of the water to produce circulation; to prevent back pressure and
resistance to circulation; to keep separate the steam and water and permit the
steam to rise freely without disturbing action upon the water.
To these ends I construct water tube boilers as illustrated in the drawings
herewith, representing in vertical section a steam generator, or one unit com-
posing a part thereof, constructed and operating according to my invention.
A is a furnace of the usual construction, provided with a front frame B, a
fire grate C and a chimney way 1). E is a steam chamber and F a similar chamber
containing water, supplied at V. T is a check valve or non-return valve between
the steam and water chambers, E and F, opening towards the latter. R is a similar
check valve between the water chamber F and the generating tubes G, L, M
and O. a, a, a, a represent bubbles of steam as they are observed to form in
transparent evaporating tubes arranged for experimental purposes.
In the drawing the left or first column of figures indicates approximately the
degree of temperature of the water and steam in the tubes. The second column
of figures indicate approximately the temperature of the gases of combustion, in
both cases by the Fahrenheit scale. .
In the operation of my improved generator an essential feature is that the
course of the water in circulation is downwards towards the fire and from the
lowest to the highest temperature in the furnace, the scale of temperature being
the reverse of common practice, evaporation taking place progressively during
the descent of the water.
Another essential feature of my invention is in providing for the free passage
and escape of steam by expanding or increasing the size of the generating tubes
from the point where evaporation begins, or approximately so, to the uptake pipes
which are made as large or larger than the final evaporating tubes; also in means
to effectually separate the steam and water, as hereinafter explained.
In a steam generator having tubes as shown in the drawing, evaporation or a
changed condition of the water, when the conditions are normal, begins at the
tube L, or for example at a temperature of about 387 degrees F. in the tubes and
about 1000 degrees in the furnace, as indicated by the bubbles a, and the scales
of temperature seen in the drawing.

page_text: .
The volume of steam and water combined is increased accordingly. Their
relative volumes being at ordinary pressure approximately as 125 to 1 and their
respective velocities in due proportion, it will be evident that unless the
tubes L, M, N, are progressively increased in size, a resistance to flow will result
and neutralize to the same extent the gravity head of the water and retard circu-
lation, which depends on the force of this head.
I therefore enlarge the size of the evaporating tubes from the point where
evaporation into steam begins, or as near that point as is ascertainable, continu-
ing such enlargment in proportion to the volume and velocities of the water
and steam taken together, to a point where the water is wholly evaporated in
the tube O, as indicated in the drawing, and then continue this maximum size
or bore through the uptake steam pipes P to the steam chamber E.
In
Any entrained water that may in starting, or from any cause in operating,
pass up the pipe P and into the chamber E, at once flows down into the water
chamber F. The water in the chamber is maintained at some predetermined
level by the usual means of supply and observation or by automatic means.
case of an over-supply of water, or if from any other cause the water should rise
too high in the chamber F, the valve T closes and prevents the water from
entering the steam chamber E. The same conditions apply to the check valve R
between the pipes G and the water chamber F, so that the circulation of water
cannot from any cause be reversed, but must continue downwards, as indicated
by arrows in the drawing.
In theory the dimensions of the pipes L, M, N, should gradually increase from
the point where the conversion into steam begins to the point where evaporation
is complete; but tapered pipes being costly and difficult of construction, it is
found sufficient in practice if the pipes are serially increased in bore as shown.
The cheek valve T between the water and steam chambers F and E and the
valve R between the water chamber F and the evaporating tubes G, L, M and O,
while not strictly essential to the operation of the steam generator under normal
conditions, may serve useful purposes as hereinbefore explained and guard against
back-flow or reverse circulation when evaporation commences.
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, series or units of evaporating tubes disposed in tiers
in a heating furnace, connecting to superimposed steam and water chambers,
such tubes increasing in size in the direction of flow approximately as the volumes
of steam and water therein, and from the top downward in the furnace, sub-
stantially as herein explained and described.
2. In a steam generator, separate superimposed chambers for steam and water,
the steam chamber set above and draining into the water chamber by a connection
between the two, a series of evaporating tubes of successively increasing size
connecting through a heating furnace from the water to the steam chamber and
arranged for the passage of water from the top downward, or from the coolest to
the hottest portion of the heating furnace, substantially as herein before described.
3. In a steam generator, separate superimposed chambers for steam and water,
a communicating passage between these chambers and a check valve therein, evapor-
ating tubes of successively increasing size connecting to and extending downwards
from the superimposed water chamber, a check valve or valves to prevent
upward or back-flow from the evaporating tubes, or from the water to the steam
chambers, in the manner and for the purposes substantially as herein explained.
Dated this 30th day of June 1890
ALLISON BROS.
Agents for the Applicant.