Improvements in and relating to Evaporators and Feed Water Heaters,
Year: 1891

page_text: Date of Application, 31st Dec., 1891-Accepted, 6th Feb., 1892
COMPLETE SPECIFICATION.
Improvements in and relating to Evaporators and Feed Water
Heaters,
I, LINDSAY BURNET, of Moorepark Boiler Works, Govan, Lanarkshire, Boiler-
maker, do hereby declare the nature of my invention, and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement in writing, that is to say:-
This invention has reference to and comprises new or improved constructions or
arrangements and combinations of the parts of evaporating vessels and feed water
heaters or economisers, specially suitable for supplying auxiliary feed water for´
steam boilers, and for heating the main supply of feed water, entirely or partially
by means of the steam supply generated in said evaporating vessels.
And in order that this invention, and the manner of performing or carrying the
same into effect or practice may be properly understood, I have hereunto appended
three explanatory sheets of drawings in which the same reference figures are used
to indicate corresponding parts in all the figures where shown.
Figure 1 on Sheet 1 is a sectional elevation of a vertical form of steam heating
and water or liquid evaporating vessel as constructed in accordance with one
arrangement of my improvements.
Figure 2 is a corresponding view of a slightly modified construction of evaporator,
in which downward or return water circulating tubes 19 are arranged inside the shell
of evaporator instead of the circulating pipe 9 fitted outside the shell 1 as in
Figure 1.
C
Figure 3 is a sectional elevation of an arrangement of annular tubes ce² which
would or may be used if these evaporators were used on the multiple effect system,
as hereinafter described.
Figure 4 on Sheet 2 is a sectional elevation of a vertical evaporator analogous to
that shown in Figure 1, but in which the water circulating tubes are shown as fixed
in a removable case. While Figures 5 and 6 are a longitudinal and a transverse
section respectively of a horizontal arrangement of large sized evaporator in which
the circulating tubes are also shown as fixed in a removable case.
Figures 7, 8 and 9 on Sheet 3 are sectional elevations of arrangements of feed-
water heaters or economisers hereinafter referred to.
Referring to these drawings:-The evaporator represented by Figure 1 consists
of an outer shell 1 of steel plate or other suitable material, preferably cylindrical,
and is fitted with a cover 2 and bottom 3 secured to the angle end rings 4 and 5 by
means of screw bolts and nuts, so as to allow of access to the interior of the
apparatus. The heating surface consists principally of vertical tubes 6 which are
secured to the separate tube plates 7 and 8, rivetted by capped flanges to the inside
of the shell 1. A pipe 9 is provided, or in place of this other arrangements are
made, as will hereinafter be described, for the downward or return circulation of
the water from the upper to the lower parts of the vessel. The non-return feed
check valve for the supply of water to the evaporator is preferably placed upon this
pipe 9, as indicated at the point 10. The steam to evaporate the water in the
apparatus enters at the branch 11 and surrounds the tubes 6 filling the space
between the tube plates 7 and 8. An air cock is fitted at 12 for the purpose of
allowing any air to escape. This cock may be replaced by an automatic valve
which will remain open when only cold air is passing but which will be caused to
close when the hot steam begins to come. A drain cock or valve is also placed at
the lowest part of the steam space 13, this cock or valve may lead into or be replaced
by a steam trap which will allow only water to escape. A water gauge may be fitted
to shew there is no accumulation of water in the steam space. Baffle plates (not

page_text: shewn) may be fitted in the steam space for the purpose of causing circulation of
the steam. Hand or manholes may also be provided for inspecting and cleaning
the interior of the steam space. The water to be evaporated fills the evaporator to
a height which covers the upper end of the circulating pipe 9. When the steam is
admitted at 11 the heat transmitted to the water in the tubes 6 causes an upward
movement of the heated water through them due to its displacement by the heavier
water in the downward circulating pipe 9, as indicated by the darts. As this
upward motion of the water may cause spray to project into the steam space and so
cause priming to a certain extent a baffle plate 14 is fitted for the purpose of
deflecting the spray. A modification of this baffle plate 14 is shown in Figure 1A
of a conical shape with a hole in the centre and a baffle cap above, which causes
any spray or water passing to run back over the cone 14. A small conical cap or
deflecting plate 15 is also placed near the top of the generated steam spaceivessel 1,
over the internal pipe 16 which conducts the generated steam to the outlet casting
or branch chest 17 upon which may be placed the safety valve 18. A salinometer
cock may be provided for drawing of a quantity of the liquid for the purpose of
ascertaining its density. A water gauge is also provided for shewing the height of
the liquid in the evaporator 1. The other necessary fittings are a pressure gauge,
blow off cock, and cleaning doors. All the fittings are preferably placed on the
body of the apparatus so that the cover 2, and bottom 3 may be removed without
disturbing any of them.
Figure 2 differs from Figure 1 in that several tubes 19, which may be arranged
on both sides of the heating tubes 6 as shewn or which may be all arranged on one
side of the said tubes, are used to replace the circulating pipe 9 in Figure 1, for
the downward return of the water, as indicated by the darts in this figure also.
With this arrangement the feed check valve 10 is preferably placed above the tube
plate 7 and on the shell of the evaporator as shewn at 20. The construction and
other mountings are substantially the same as these enumerated for Figure 1 and
figured to correspond.
Figure 4 shows an arrangement of evaporator analogous to that shown in
Figure 1 and figured to correspond, except that the steam heating space is formed
of a separate removable close vessel a with the heating tubes 6 secured in the upper
and lower plates 7 and 8, the whole vessel a and tubes being made removable through
n doorway b secured to one side of the outer shell 1, and secured by screw bolts and
nuts to flanges a bon the outer end plate of the vessel a, and the inner end of the
vessel a rests on brackets at , secured to the inside of the vessel 1 opposite to the
doorway h, the inlet steam branch 11 being secured to the upper part of this flanged
end to admit the steam to the vessel a, while the drain branch 13 is bolted to the
lower part of this end plate a".
Figures 5 and 6 show a horizontal arrangement of evaporator with a removable
elliptical vessel a having the heating tubes 6 secured in its upper and lower
plates 7 and 8, and removable through a door b at one end, being bolted by
flanges a bat this end for that purpose. The inlet steam branch 11 and drain
pipe 13, are secured at the upper and lower parts of the end plate all as in the
arrangement shown in Figure 4.
These evaporators Figures 1 to 6 may be worked as single effect or as multiple
effect evaporators as is well known. When worked as multiple effect evaporators,
I prefer to employ in place of the external circulating pipe 9 or the tubes 19 the
internal circulating device shewn in Figure 3. This consists of two or more large
tubes c secured at their ends in the plates 7 and 8 of the evaporator, preferably
near the outer shell, and internal circulating tubes c are suitably supported within
these c by open or perforated rings so that the upward annular current due
to the heat on the external tube e will not interfere with the downward current
within the internal tube c'. This arrangement renders the apparatus more compact
as all the tubes are contained within the outer shell. In the case where it is
not desirable to mix the steam and the fluid to be heated a modified form of the
evaporator may be used, the heating surface consisting of vertical tubes as shewn

page_text: but the baffle plates are omitted. The space above the upper tube plate is reduced
but the arrangement of circulating pipes is retained as in the evaporators shown.
In order to render the apparatus economical, I use an economiser or feed-heater
in connection with the last evaporator of the series. This economiser or feed-
heater is for the purpose of utilizing the heat of the steam generated in the last
evaporator to heat the main supply of feed water for the boilers. In some cases
where the supply of steam from the evaporator is insufficient to heat the feed
water to the desired temperature the economiser or feed heater is so constructed
that additional steam may be admitted from another source.
The economiser may
be such (1) that the heating steam mixes with the liquid to be heated (2) that the
steam is kept separate from the liquid.
Figure 7 shews a form of the first type of economiser 21. The action is similar
to that of an injector. 24 is the water inlet, 25 the water outlet, 26 the steam
inlet, all as indicated by the arrows, 27 is the air outlet, 28 the scum outlet. The
steam entering at 26 becomes condensed among the water surrounding the nozzle
and imparts motion to the said water and thus by the formation of the apparatus
causes a circulation of the whole of the water in the heater 21. The water is
thus uniformly heated and at the same time the steam is more surely condensed
than in still water. The form of the economiser 21 may be varied and the
injector 26 and combining nozzle part 22 placed entirely outside of the main
vessel 21 as in Figure 8. Or the current of water in the economiser vessel 21
may flow to the injector nozzle 22, in the opposite direction to that shewn in
Figure 8, as is shewn in Figure 9 with the combining and steam nozzle 22, 26,
inverted.
As the steam supply from most evaporators is insufficient to obtain a desirable
temperature in the main feed water, may provide two or more steam inlets with
connections so that each steam supply may act upon the water contained within
the economiser or feed heater without in any way interfering with the action of
steam from another source.
The evaporators Figures 1 to 6 can be used without the economisers Figures 7
to 9 described but a complete evaporating plant for the supply of fresh auxiliary
feed on board ship would include them both.
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:
First. The construction and arrangement and combination of evaporators and
feed water heaters or economisers, substantially as and for the purposes herein
described and distinguished in reference to and shown in the accompanying
drawings.
Second. The construction of evaporators with steam heating vessels and water
circulating pipes or tubes and fittings, substantially as and for the purposes herein
described and distinguished in reference to and shown in Figures 1 to 6 of the
accompanying drawings.
Third. The construction of feed water heaters or economisers, with steam
injecting combining nozzles and circulating arrangements substantially as and for
the purposes herein described and distinguished in reference to and shown in
Figures 7, 8, and 9 of the accompanying drawings.
Dated 30th December 1891
W. R. M. THOMSON & Co.,
96, Buchanan Street, Glasgow, Agents.