Feed Water Heaters.
Year: 1890

page_text: Date of Application, 7th Oct., 1890
Complete Specification Left, 7th July, 1891-Accepted, 15th Aug., 1891
Feed Water Heaters.
I, JAMES ATKINSON, of 3 Nassington Road, Hampstead, London, N.W.
Engineer, do hereby declare the nature of this invention to be as follows
:-
This invention is for the purpose of heating the feed water supplied to a steam
boiler to a temperature equal to or closely approaching that of the temperature of
the steam in the boiler.
An important fact known to many engineers, is that heating surface will transmit
a much greater number of units of heat when employed for the purpose of
evaporating water, that is to say, converting it into steam, than when employed in
raising the temperature of the water to the boiling point. From experiments
which have been made the number of units of heat in the one instance have
been shown to be more than three times as many as in the other instance. It
follows from this, that the heating surface of steam boilers would be more usefully
employed in evaporating water than in raising the water to the boiling point
corresponding to the pressure of steam; also, that provided no other source of
heat is available, it would be more economical to raise the feed water to the
temperature of the steam in the boiler, by means of steam directly used from the
boiler, for this purpose, than to put the feed water in at any lower temperature.
This will be more fully understood by taking the instance of a steam boiler
working at 180 lbs. absolute. The corresponding steam temperature is 373° F.,
presume that feed water is drawn from the hot-well at 100° F., a total of 1117 units
of heat is required to convert one pound of feed water into stean, 263 of these units
being necessary to raise the water to the boiling point, and 854 units required to
evaporate it into steam. Thus more than 24 per cent. of the heat is required
to boil the water, and this 24 per cent. of the whole duty of the heating surface of
the boiler might be rendered three times more efficient if all the water was put into
the boiler at 373° F., so that even by taking fresh steam from the boiler for this
purpose a great saving of fuel may be made in most instances. Increasing the
efficiency of 24 per cent. of the heating surface three times, is virtually the same as
increasing the total heating surface by 48 per cent.
The apparatus for heating the feed water by means of fresh steam from the
boiler consists of a chamber into which the feed water is pumped or otherwise
delivered, it passes into this chamber through a nozzle in combination with a steam
nozzle supplied by fresh steam from the boiler, the two nozzles act more or less as
an injector. The lower part of the chamber is fitted with a pump which I prefer
to make of say 50 per cent. larger capacity than the feed pump on the engine, the
pump is fitted with ordinary suction & delivery valves but in addition the piston
passes holes drilled through the barrel of the pump when near the end of its suction
stroke, so that the pump is completely filled, say two-thirds with water, and the
balance with steam at, or very nearly at, full boiler pressure; the pump is so
arranged that the water and steam are drawn past a pendent edge (or edges) so as
to thoroughly intermingle them. The greater capacity of the pump insures the
highest possible temperature of the water, and also prevents any air or uncon-
densable vapour from accumulating in the apparatus; as it does not require much
power to drive it, there is very little objection to its increased size, and under
certain circumstances it might with advantage be made considerably larger than
50 per cent. increased capacity.
The apparatus may be combined with other means of heating the feed water at
lower stages; for instance, with an ordinary high pressure non-condensing engine,

page_text: a surface feed water heater may be first used so as to obtain all the heat attainable
from the exhaust steam. Again, with compound, or other multiple expansion
engines two or more of these apparatus may be combined so as to heat the feed
water in stages by steam taken from the receivers between the various cylinders, it
being understood however that in the final stage steam from the boiler is used, or
this steam may be taken from the main steam pipe.near the engine, the jacket, or
the steam chest to the high pressure cylinder so as to drain these thoroughly; the
steam from the various receivers may also be taken at the lowest point so as to
keep them drained.
In some instances the apparatus may be simplified by doing away with some of
the pumps, as for instance, in a tripple expansion engine the steam from the receiver
between the low pressure cylinder and the intermediate cylinder passes into the
injector supplied with feed water from the hot-well by the main feed pumps on
the engine, this first injector would relieve the pumps of some or all of their load,
the water then passes without being pumped into a second nozzle working in con-
junction with steam from the receiver between the high pressure cylinder and
the intermediate pressure cylinder; the feed water again passes without being
pumped into the third injector which is supplied with boiler pressure steam, a
pump as described connected to the final chamber would give certainty of action
throughout. Suitable means of regulating the nozzles can be provided, and a
pump at each end of the system would prevent any trouble in working.
Regulating and self acting valves may be placed where desirable, and self-acting
valves on the various steam pipes would prevent any water passing into the engine
in case of anything interfering with the action of the injectors. I should prefer to
place a large air vessel on the delivery pipe from the main feed pumps on the
engines, so as to equalize the flow of water to the injectors, a small valve and
connection to the condenser would be useful to carry any excess of air passed by
the main feed pumps, this could be arranged to draw from the lower part of the air
vessel, and if a short piece of glass tube was inserted in the connection the
small valve could be readily adjusted so as not to pass any material quantity of
water back.
The pumps at either end of the system might perhaps be omitted, but both of
them would be useful in giving more absolute control over the various temperatures
and pressures.
Filters or lime catchers may be inserted in any suitable part of the system.
Additional steam supplies may be used if formed desirable in giving more
control over the temperatures in any part of the system.
In most multitubular boilers the furnaces form the heating surface in the lower
parts, and this is the surface mostly affected; as this is rendered more efficient it
follows, that the furnace plates will work at a much lower temperature and will not
be so liable to collapse.
The water being at a more equitable temperature throughout the boiler, there
will be less straining and chance of leakage at the lower seams.
When engines are already fitted with heaters such as those described by James
Weir and George Weir in Letters Patent No. 61907 the feed water after leaving
such heaters could be passed into a final chamber provided with injector nozzles
and pump as described above, the steam nozzle being provided with full boiler
pressure, so that the additional economy resulting from the increased temperature
of the feed water might be obtained.
A due appreciation of the cause of the economy to be made by heating the
feed water to full boiler temperature shows, that the greatest amount of economy
is to be made with boilers deficient in heating surface and working at high
pressures.
Dated the 7th day of October 1890

page_text: COMPLETE SPECIFICATION.
Feed Water Heaters.
I, JAMES ATKINSON, of 3 Nassington Road, Hampstead, London N.W.
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:-
This invention is for the purpose of heating the feed water supplied to a steam
boiler to a temperature equal to, or closely approaching that of the temperature of
the steam in the boiler, or partially, to lower temperatures.
An important fact known to many engineers, is, that heating surface will
transmit a much greater number of units of heat when employed for the purpose of
evaporating water, that is to say, converting it into steain from the fluid state at
boiling point, than when employed in raising the temperature of the water to the
boiling point. From experiments which have been made the number of units of
heat in the one instance have been shown to be more than three times as much as
in the other instance. It follows from this that the heating surface of steam boilers
would be more usefully employed in evaporating water than in raising water to the
boiling point corresponding to the pressure of steam; also, that provided no other
source of heat is available, it would be more economical to raise the feed water to
the temperature of the steam in the boiler, by means of steam used directly from
the boiler for this purpose, than to put the feed in at any lower temperature.
This will be more fully understood by taking the instance of a steam boiler
working at 180 lbs. absolute. The corresponding steam temperature is 373° F.
presuming that the feed water is drawn from the hotwell at 100°, a total of
1117 units of heat is required to convert one pound of feed water into steam, 273 of
these units being necessary to raise the water to the boiling point, and 844 to
evaporate it into steam. Thus more than 24 per cent. of the heat is required to boil
the water, and this 24 per cent. of the whole duty of the heating surface of the
boiler might be rendered (say) three times as efficient if all the water was put into
the boiler at 3730°; so that, consequently, by taking fresh steam from the boiler for
this purpose a great saving of fuel may be made in most instances. Increasing the
efficiency of 24 per cent. of the heating surface to three times is virtually the same
as increasing the whole of the heating surface by 48 per cent.
To enable this invention to be fully understood I illustrate an arrangement of
this apparatus in the accompanying sheets of drawings, in which Fig. 1 Sheet 1 is a
longitudinal section, Fig. 2. Sheet 1. a section at right angles to Fig. 1 and Fig. 3
Sheet 2 is a plan. The arrangement thus shown would be suitable for a compound
engine in which the feed water taken from the hotwell is partially further heated
by steam taken from the receiver between the two cylinders, and its temperature
finally heated to, or almost to, the full boiler temperature by steam which is taken
from the boiler or main steam pipe. I employ a pump A specially arranged to
cause as little resistance to the suction and delivery as possible; in this instance,
I have shown it as a double-acting pump, one end of the pump being used for one
stage of heating and the other end for another stage, (say) the final one where
boiler steam is used; each end of the pump is fitted with a large, light suction
valve B, and similar delivery valve C. The suction valve B is arranged to open
communication to the large heating chamber D, and a similar suction valve at the
other end of the pump to the separate chamber D. The chamber D is supplied
with steam from the receiver through the non-return valve E and with water from
the feed pump on the engine or other source, and the chamber D' is supplied with
steam from the boiler through the non-return valve E' and with water from the
delivery valve C; the water from the delivery valve communicating with the other
end of the pump passing on to the boiler. The pump A is fitted with a long
piston F and at the one end of its stroke, in the position shown, it overruns holes G

page_text: drilled through the barrel of the pump and communicating with the chamber D;
when at the other end of its stroke the other end of the piston uncovers other
holes G communicating with the chamber D¹. The piston F may be driven in
any convenient manner. The pump A is of such a capacity and is driven at such a
speed that the delivery quantity of each end is considerably in excess of the actual
quantity of feed water passing through, say to the extent of 50 per cent. or upwards,
this excess of capacity ensures the thorough removal of any air which might
interfere with the proper action of the apparatus and also that some steam is
pumped with the water thus keeping the water up to the highest available
temperature.
Special arrangements are provided for bringing the steam and water into
intimate and rapid contact. The steam from the receiver and boiler pass through
nozzles similar to injector nozzles, H' Fig. 2. Sheet 1. showing that for the boiler
steam, and a similar one is provided for the steam from the receiver. The water
passes with the steam through combining cones, 11 being the cone through which
the water from chamber D after being forced through the delivery valve C passes
into the chamber D'. These acting to some extent more or less as injectors
will to a similar amount relieve the pumps; they allow the steam and water to
mix rapidly and put the combined jets into rapid motion; the jets are directed
onto shelves which break the water up so that the steam is brought into intimate
contact with the small particles, which are thus raised to the full temperature of
the steam due to the pressure they are at. The heated water falls to the bottom
of the chambers D, D and may be drawn past pendant edges K so as to ensure
the heating to the highest available temperature when being drawn into the pump
through the light suction valves; the holes G, G¹ being for the purpose of ensuring
the pump being filled with water and steam at the highest possible pressure and
temperature.
Instead of employing each end of the pump for different stages of heating, a
double-acting pump may be used for each stage, or a plunger pump may be used.
With tripple expansion engines, three stages may be used and with quadruple
expansion engines four stages; it being understood that to obtain the greatest
possible economy it is necessary to heat the feed water finally, with steam at or
about full boiler pressure instead of allowing this final heating to be done by
the heating surface in the boiler.
When used with non-condensing engines and it should be desired to exclude
all grease from the boiler, the feed may be first heated by means of a surface
heater and the exhaust steam and finally raised to boiler temperature by means
of this apparatus.
I prefer to take the full pressure steam to be used in this apparatus from the
main steam pipe near the engine, or the steam jacket if this is filled with boiler
pressure steam, thus thoroughly draining these and assisting in ensuring dry steam
being supplied to the cylinder. Also for similar reasons the steam taken from
any receiver should be taken from such a place as to drain that receiver.
Where there are several stages of heating it may not be necessary to employ a
pump for cach stage.
Air-vessels may be employed to equalize the flow of water through the nozzles,
and arrangements made for adjusting the area through the nozzles, so as to give the
best effect.
Additional steam supplies may be used if found desirable either in the form of
compound nozzles or otherwise, and in some instances to save complication the
steam from one receiver may be used in conjunction with steam from another
receiver or from the boiler in a combined set of nozzles so as to form two stages of
heating.
Filters or lime-catchers of any known design may be inserted in any suitable
part of the system.
In most multitubular boilers the furnaces form the heating surface in the lower
parts and this is the surface mostly affected; as this is rendered more efficient, it

page_text: follows, that the furnace plates will work at a lower temperature and will not be so
liable to collapse.
The water being at a more equitable temperature throughout the boiler, there
will be less straining and chance of leakage at the lower seams.
A due appreciation of the cause of the economy to be made by heating the feed
water to full boiler temperature shows, that the greatest amount of saving can be
effected by these means with boilers deficient in heating surface, and working at
high pressures.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. In apparatus for heating feed water for boilers the combined use of nozzles
and pumps for increasing the temperature and pressure in stages as described and
illustrated.
2. The use of a set of nozzles working with steam at or about full boiler pressure
in combination with a pump for the purpose of delivering the feed water into the
boiler at a temperature equal to or closely approaching the temperature of the steam
in the boiler, the feed water having previously been at some lower pressure and
temperature and the nozzles and pump being in connection with a large mixing and
depositing chamber as described and illustrated.
3. The use of a pump having very light valves and holes through the barrel of
the pump passed by the piston and of increased capacity so that it will completely
fill itself with a mixture of water and steam, when working in combination with
other apparatus such as nozzles and used for the purpose of increasing in one
or more stages the temperature and pressure of feed water, as described and
illustrated.
4. The general construction and arrangement of feed water heating apparatus as
described and illustrated.
2
JAMES ATKINSON.