AN IMPROVED METHOD OF AND MEANS FOR PREVENTING EXPLOSIONS OF STEAM-BOILERS
Year: 1880

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "AN IMPROVED
METHOD OF AND MEANS FOR PREVENTING EXPLOSIONS OF STEAM-BOILERS."
A communication from abroad by Daniel Thomas Lawson, of Wellsville, in
the County of Columbiana, State of Ohio, United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 28th April 1880.
ALEXANDER MELVILLE CLARK, of, 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "AN IMPROVED METHOD OF AND MEANS FOR PRE-
VENTING EXPLOSIONS OF STEAM-BOILERS." [A communication from abroad by
Daniel Thomas Lawson, of Wellsville, in the County of Columbiana, State of Ohio,
United States of America.]
Water boils under the normal pressure of the atmosphere at 212° F. Under a
pressure of 10 lbs. to the square inch a heat of 239° is required to make it boil;
under 50 lbs. to the square inch 298° is required; and under 100 lbs. pressure to the
square inch 338° of heat is required in all the water in the boiler to keep the steam
pressure to that point, ie., to 100 lbs. to the square inch, and just as the steam
pressure is increased, so the heat in the water must be proportionately increased or
else the steam pressure required cannot be had.
When water is thus superheated it becomes as explosive as gun powder, but it
does not explode in the same manner as powder explodes by chemical union upon
ignition, but by bursting into steam from a reduction of pressure. Thus the
engineer opens the throttle valve and the cylinder is instantly filled with steam,
which creates a vacuum to that extent in the boiler. The superheated water then
immediately jumps to fill the vacuum, and is met by the valve instantly cutting off
the escape into the cylinder, which causes a concussion on every square inch in the
boiler much greater than the regular pressure of the steam.
The present inventor states that he has abundant reason to believe that it is this
concussive action which causes the numerous and mysterious boiler explosions, and
...

page_text: which cause is wholly independent of the amount of water in the boiler, in fact the
greater the amount of water in the boiler the more terrific the explosion.
Another cause of boiler explosions which occur when the pumps begin to act is
as follows: When the water gets low in the boiler or the boiler careens, the cold
feed water is injected directly into the steam space. It thus acts to condenso the
steam and for an instant suddenly reduces the pressure. Immediately after the
momentary condensation the superheated water again bursts into steam, and by a
concussive action involves a strain of the same general character as that which is
constantly going on during the escape of steam through the cylinder ports, but of a
more intense character.
The present invention which is based upon this theory consists in reducing the
concussive strain produced by the impulsive and intermittent escape of steam to
the cylinders to an approximately uniform pressure, by rendering the evolution or
passage of steam from the water to the steam space approximately constant, and
independent of the intermittent discharges from the steam space to the cylinder;
and the means for accomplishing the same consist in a boiler constructed with a
partition intervening between the water space and the space whence the steam is
taken to supply the cylinder, and feeding the steam as it is generated through a
valve or orifice in said partition of a smaller size than the port or opening through
which the steain passes into the cylinder. By this means the normal steam
pressure or steam supply when thus intermittently or alternately reduced is restored
gradually by reducing the flow from the water space to the steam space, so that the
transformation of water into steam is made approximately uniform in spite of the
intermittent escape of steam through the cylinders, and the boiler is thus relieved
of the constant wear and strain of the concussion.
The opening in the partition is preferably controlled by a valve operated from
the outside of the boiler, so as to enlarge or reduce the size of the orifice leading
from the water compartment to the steam compartment. For practical purposes
the orifice should be about 1/, as large as the outlet for the steam to the cylinder,
and when so relatively proportioned it will be found that although a considerable
body of steam may be suddenly taken out of the steam space proper by the
opening of the cylinder valve, the protracted flow froin the lower compartment to
the upper compartment of the boiler caused by the smaller size of the orifice
retards the transportation of superheated water into steam through a period of
time sufficiently long as compared with the strokes of the piston to make tho
liberation of stenin practically uniform. In other words the superheated water
cannot jump in a body to supply the place of the discharged steam and meet with
a check by the sudden closing of the induction port, which produces a concussive
strain on tho boiler, but the reduction of the size of the orifice through which the
steam liberated from the water passes is such as to prolong the passage of steain
through said orifice over the period when the induction port valve is closed.
To avoid the concussion produced by condensation I propose to introduce the
water at a point so low that no cold water can ever come in direct contact with
the steam, and with a downward instead of an upward injection. If perchance
any cold water should thus come in contact with the steam the partition and
opening therethrough still acts beneficially for the reason that the steam space
over the water in the lower compartment is limited, and the condensation of the
steam in this space is limited in its effect.
In making use of the Invention I do not limit myself to any construction of
boiler, any arrangement of partition, or to any form of opening in the partition,
as a plain orifice of smaller size than the induction port may be used without a
valve to control its size, and still give good results.
In fitting up old boilers with the improvements I may build a supplemental
steam space above the old boiler, and connect their chambers by an orifice of the
relative size described, or I may interpose the partition between the boiler and the
steain dome.

page_text: In further defining the scope of the Invention I would state that I do not limit
myself to the use of a single orifice in the partition, as a number of small orifices
would be desirable in many cases to prevent the water from rising in a cono
beneath a single orifice.
The retardation of the passage of steam to the steam spaco may also be effected
hy frictional contact instead of the relative sizes of the openings in the partition
and eduction port; thus a fine series of openings in a foraminated plate or fibrous
diaphragm may in the aggregate he greater than the discharge outlet to the
cylinder, and yet the friction of the steam in passing through the foraminated
plate be sufficient to retard the transformation of steam.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 28th
October 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "AN IMPROVED METHOD OF AND MEANS FOR PRE-
VENTING EXPLOSIONS OF STEAM BOILERS." A communication from abroad by
Daniel Thomas Lawson, of Wellsville, in the County of Columbiana, State of Ohio,
United States of America.
Water boils under the normal pressure of the atmosphere at 212° F. Under a
pressure of 10 lbs. to the square inch a heat of 239° is required to make it boil;
under 50 lbs. to the square inch 298° is required; and under 100 lbs. pressure to the
square inch 338° of heat is required in all the water in the boiler to keep the steam
pressure to that point, i.c., to 100 lbs. to the square inch, and just as the steam pressure
is increased, so the heat in the water must be proportionately increased, or else the
steam pressure required cannot be had.
When water is thus superheated it becomes as explosive as gunpowder, but it
does not explode in the same manner as powder explodes by chemical union upon
ignition, superheated water exploding by bursting into steam from a reduction of
pressure. Thus the engineer opens the throttle valve and the cylinder is instantly
filled with steam which creates a vacuum to that extent in the boiler.
The superheated water then immediately jumps to fill the vacuum, and is met
by the valve instantly, cutting off the escape into the cylinder, which causes a
concussion on every square inch in the boiler much greater than the regular
pressure of the steam.
The present inventor has abundant reason to believe that it is this concussivo
action which causes the numerous and mysterious boiler explosions, and which
cause is wholly independent of the amount of water in the boiler, in fact the greater
the amount of water in the boiler the more terrific the explosion.
Another cause of boiler explosions which occur when the pumps begin to act is
as follows: When the water gets low in the boiler, or the boiler careens, the cold
feed water is injected directly into the steam space. It thus acts to condenso the
steam, and for an instant suddenly reduces the pressure. Immediately after the
momentary condensation the superhoated water again bursts into steam, and by a
concussive action involves a strain of the same general character ns that which is
constantly going on during the escape of steam through the cylinder ports, but of
a more intense character. The present Invention, which is based upon this
theory consists in reducing the concussive strain produced by the impulsive and
intermittent escape of steam to the cylinders, to an approximately uniform
pressure by rendering the evolution or passage of steam from the water to the
steam space approximately constant and independent of the intermittent dis-
charges from the steam space to the cylinder, and the means for accomplishing
the same consist in a boiler constructed with a partition intervening between
the water space and the space whence the steam is taken to supply the cylinder,
and feeding the steam as it is generated through a valve or orifice in said
partition of a smaller size than the port or opening through which the steam
passes into the cylinder. By this means the normal steam pressure or steam
supply when thus intermittently or alternately reduced is restored gradually by
reducing the flow from the water space to the steam space, so that the trans-
formation of water into steam is made approximately uniform in spite of the
intermittent escape of steam through the cylinders, and the boiler is thus relieved
of the constant wear and strain of the concussion.

page_text: In the accompanying Drawings Figure 1 is a vertical longitudinal section, and
Figure 2 a transverse section on line 2, 2, of a steam boiler constructed according
to this Invention, given by way of example. A is the steam boiler, which
may be of any approval shape, and be provided with fire flues A¹, A¹;
B is a partition in the same separating the boiler into two compartments,
one of which C contains the water and a small steam room, and the other
of which C' is occupied entirely by steam, and into which is tapped
the pipe lending to the cylinder. Through the partition B is formed an
opening which is preferably controlled by a valve D operated from the
outside of the boiler, so as to enlarge or reduce the size of the orifice leading from
the water compartment to the steam compartment. This orifice should, in order to
attain the object of the Invention, be smaller than the orifice through which steam
is fed to the cylinder. For practical purposes it should be about one fourth as
large as said outlet, and when so relatively proportioned it will be found that
although a considerable body of steam may be suddenly taken out of the steam
space proper by the opening of the cylinder valve, the protracted flow from the
lower compartment to the upper compartment caused by the smaller size of the
orifice retards the transportation of superheated water into steam through a period
of time sufficiently long as compared with the strokes of the piston to make the
liberation of steam practically uniform. In other words, the superheated water
cannot jump in a body to supply the place of the discharged steam, and meet with
a check by the sudden closing of the induction port, which produces a concussive
strain on the boiler; but tho reduction of the size of the orifice through which the
steam liberated from the water passes is such as to prolong the passage of steam
through said orifice over the period when the induction port valve is closed. To
avoid the concussion produced by condensation I propose to introduce the water
at a point so low that no cold water can ever come in direct contact with the
steam, and with a downward instead of an upward injection. If perchance any
cold water should thus come in contact with the steam the partition and opening
therethrough still acts beneficially, for the reason that the steam space over the
water in the lower compartiment is limited and the condensation of the steam in
this space is limited in its effect.
The Invention is not limited to any construction of boiler, any arrangement of
partition, or to any forin of opening in the partition, as a plain orifice of smaller size
than the induction port may be used without a valve to control it size and still
give good results. In fitting up old boilers with the improvements I may build
a supplemental steam space above the old boiler, and connect their chambers by
an orifice of the relative size described, or I may interposo the partition between
the boiler and the steam dome.
In further defining the scope of the Invention I would state it is not limited to
the use of a single orifice in the partition, as a number of small orifices would be
desirable in many cases to prevent the water from rising in a cone beneath a
single orifice. The retardation of the passage of steam to the steam space may also
be effected by frictional contact instead of the relative sizes of the openings in the
partition and eduction port; thus a fiue series of openings in a foraminated plate
or fibrous diaphragm may in the aggregato be greater than the discharge outlet to
the cylinder, and yet the friction of the steam in passing through the forminated
plate be sufficient to retard the transformation of steam.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is, -
1st. The method of preventing concussive strains in boilers due to the inter-
mittent escape of steam into the cylinder, which consists in retarding or prolonging
the flow of the steam from the water to the steam space through a greater length
of time than is allowed for the escape of the same quantity of steam from the
steam space, as described.

page_text: 2nd. A steam boiler adapted to carry a permanent bulk of water, having a
partition dividing the main steam space from the water space with an opening or
openings in said partition, of less area than the opening through which the steam
is led from the steam space to the cylinder.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set 5
my hand and seal, this Twenty seventh day of October, in the year of our
Lord One thousand eight hundred and eighty.
A. M. CLARK. (L.S.)