Improvements in Feed Water Heaters.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Feed Water Heaters.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention (which has been commu-
nicated to me from abroad by Augustin Normand & Co. of 67 rue du Perroy, Havre,
Seine Inférieure in the Republic of France Engineers) and in what manner the same
is to be performed to be particularly described and ascertained in and by the following
statement:-
The feed water heaters constructed according to this Invention are more especially
designed for engines working with not less than triple expansion and belong to that
class of feed heaters in which the feed water is heated by steam taken from the low
pressure intermediate receiver or chamber, that is to say the receiver or chamber
supplying steam to the cylinder that exhausts into the condenser. In apparatus con-
structed according to this Invention the steam is not brought in direct contact with
the feed water but acts upon it through metallic tubes or partitions in the same
as to heat the feed water
manner as in a surface condenser in such a manner
during its passage from the feed pumps to the boiler as hereinafter described.
This improved arrangement, which has not heretofore been proposed or employed
with steam taken from the lower intermediate receiver, offers many advantages, the
most important being that the working of the feed pumps is not dependent on the
heating of the feed water. Although it may not be necessary to expel the air from
the feed water, this may be readily done if desired by means of a small pipe connecting the
lower part of the air vessel above the delivery pipe of the feed pump with the suction
pipe of the said pump. Provided that the suction pipo rises gradually towards the
hot well the air returns to tho hot well and no water is wasted. This arrangement has
been employed for many years in marine engines.
The heating steam always contains a small proportion of air which is liable to
accumulate in that part of the heater occupied by steam and impede the entrance of
fresh steam. This air is got rid of in the improved apparatus by connecting the part
of the steam space in the water heater opposite that at which the steam enters,
with the condenser or with the hot well through a small orifice and pipe. Although
the greater part of the steam is condensed in passing through the heater, a small
quantity remains uncondensed and is usually carried away by the air. The water
resulting from the condensation of the steam used for heating the feed water is
conveyed into a steam trap, and from thence to a waste pipe, which also receives the
air pipe hereinbefore referred to as being connected to the heater. The mixture of
air steam and condensed water in this waste pipe contains a certain quantity of heat
which may be utilised. With this object when the pressure in the steam space of the
water heater is above atmospheric pressure, the said mixture is discharged into the
water in the hot well; when it is lower, it is sent to the condenser. In both cases,
but especially in the latter, the discharge takes place after passing through a worm
or coiled pipe or other like apparatus presenting an extended cooling surface,
immersed in the hot well. In the latter case, the exhaust should take place under
water, at the bottom of the condenser or in the pipe connecting the condensor with
the air pump. In both cases, the temperature of the feed water is raised, sufficiently
to lessen appreciably the quantity of steam taken from the low pressure receiver,
but not enough to interfere with the proper action of the feed pumps.
And in order that the said invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheets of drawings. the same letters of reference indicating
corresponding parts in all the figures.

page_text: Figures 1, 2 and 3 of the annexed drawings show in end and side elevation and in
plan respectively an example of an arrangement that can be employed in carrying
out this invention in practice.
A is the pipe conveying steam from the low pressure intermediate receiver into
the feed water heater B. This pipe should be of large diameter in order that the
difference of pressure between the receiver and the heater may be as small as possible.
The feed water heater B may be slightly inclined (Figure 2) and is provided
internally with a number of tubes 6 represented by dotted lines in Figure 2 and
shown more clearly in Figure 4 which represents the heater B in transverse section.
Steam circulates inside these tubes and the feed water, circulates in the space on the
exterior of the said tubes. This arrangement may be reversed if desired. The steam
is admitted at the higher end of the heater and the feed water being supplied from
feed pumps (not shewn in the drawing) at the opposite end through a pipe C, passes from
the heater to the boiler through a pipe D. The motion of the feed water, necessary
to the transmission of heat is increased by check plates or baffles E, E, E, shown by
dotted lines in Figures 2 and 3 their edges being placed vertically so that the air
contained in the feed water may escape more readily. The heater B is constructed
in such a manner as to provide for the unequal expansion of the different parts
and prevent leakage at the joints. With this object curved tubes. may be employed
or the flanges at the end of the shell or casing may be made of such width as to
impart to them the required elasticity.
Fis a pipe through which the air contained in the steam is drawn off through a
small cock f. G is a pipe through which the water produced by the condensation
of steam in the heater is conveyed to a steam trap H. From this steam trap the
water passes through a pipe I, (communicating with the other end of the air pipe F)
to a worm L in the hot well K. J is a three way cock by which the mixture of
air steam and hot water contained in the pipe I and worm L is sent either to the
hot well K. or to a condenser not shown in the drawing according as the pressure
in the steam space of the water heater is above or below the atmosphere. In the
latter case, the worm L immersed in the hot well transmits to the feed water part
of the heat contained in the waste steam and water before it reaches the condenser.
Non return valves should be provided in both branches of the pipe I, so as to render
it impossible for the water contained in the hot well or in the condenser to enter
the steam space of the heater or the intermediate receiver. The air pump exhausts
or discharges through a pipe M connected with the upper part of the hot well K. and
the feed pumps draw water from this well through pipes N.
The action of this apparatus is as follows:-Steam from the intermediate chamber
supplying steam to the last or lowest pressure cylinder of the engine passes through
the pipe A into the space at the end of the heater B whence it flows through the
heating tubes 6 to the space at the other or lower end of the heater. From this end of
the heater the water of condensation passes through the pipe G, steam trap H and
pipe I to the worm L in the hot well K. After circulating in the worm L the steam
is directed by the three way cock J either into the hot well through a pipe P in case
the pressure in the heater is above atmospheric pressure or into the condenser of the
main engines through a pipe Q when the pressure in the heater is below atmospheric
pressure.
The water drawn from the hot well K through the pipes N is delivered by the feed
pumps to the heater B through the pipe C and after being heated by circulating in
contact with the external surfaces of the steam heated tubes b, passes through the
pipe D to the boiler.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
First. Heating feed water in triple or higher expansion engines by means of steam
taken from the low pressure receiver that is to save the receiver or intermediate

page_text: chamber supplying steam to the cylinder or cylinders exhausting into the condenser,
the said steam being caused to act through tubes or partitions on the feed water
passing from the feed pumps to the boiler or boilers and not by direct contact with
the said water substantially as hereinbefore described with reference to the accom-
panying drawings.
Second. Separating or removing the air contained in the heating steam by connect-
ing the steam space in the heater at the end opposite to that where the steam enters
with the condenser or with the hot well through a pipe of small sectional area sub-
stantially as herein before described.
Third. Utilizing the heat contained in the steam that escapes with the air and in
the water of condensation from the steam heater by causing the said steam and water
to pass through a worm or equivalent apparatus immersed in the hot well and be
discharged either into the hot well or into the condenser, according as the pressure
in the steam space of the heater is above or below that of the atmosphere substan-
tially as herein before described.
Fourth. The arrangements and combinations of parts constituting the improvements
in feed water heaters substantially as herein before described with reference to the
accompanying drawings.
Dated this 20th dev of June 1800
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, W.C., Agents.