Method of and Apparatus for Heating or Evaporating Liquids.
Year: 1893

page_text: Complete Specification Left, 23rd Jan., 1893-Accepted, 18th Mar., 1893
COMPLETE SPECIFICATION.
Method of and Apparatus for Heating or Evaporating Liquids.
I, ERWIN HERZ, of I Schwarzenbergplatz 1-3, Vienna, in the Empire of
Austria, Chief Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
This invention relates to a method of and apparatus for heating and evaporating
liquids, the apparatus consisting essentially of a number of tubes, exhausted of air
as much as possible, acting as heat transmitters and partly filled with a small
quantity of liquid, and having their lower part suspended in a furnace. The upper
parts of the said tubes project into the evaporating boiler which is situated above
the furnace and is entirely separated from the latter aud contains the liquid to be
vaporized.
The heat of the combustion gases convert into steam or vapour part of the liquid
contained in the tubes, and this steam or vapour rises into the upper part of the
tubes which is situated within the boiler, and is there condensed, its latent heat
being at the same time absorbed by the liquid surrounding the upper parts of the
tubes and which it is desired to heat or to evaporate.
When condensed, the steam or vapour in a liquid form runs down into the lower
end of the tubes, arranged within the furnace, and is reconverted into steam or
vapour.
The quantity of liquid contained in the tubes is so calculated that even if the
furnace ends of the tubes are heated to the utmost, the whole quantity of the liquid
will not be converted into steam or vapour, but only a part of it; and since the
liquid mass in contact with the upper parts of the tubes rapidly absorbs the heat of
this steam or vapour there is no possibility of the steam or vapour produced by
partial evaporation of the liquid in the tubes ever being overheated.
The tubes arranged in this manner and projecting upwards into the boiler receive
from the furnace an amount of heat, which may vary between certain limits, and
transmit the same to the steam or vapour they contain, and also transfer heat by
way of direct transmission to the liquid which surrounds them in the boiler.
In this manner, there is a constant circulation going on within the tubes, since
the steam, produced by evaporation of the liquid, and the superheating of which
is prevented by the excess of liquid remaining unvaporized and by the above
mentioned rapid absorption of heat, rises within the tubes until it reaches a point
sufficiently out of reach of the action of the furnace to be condensed.
densed liquid then flows down into the furnace ends of the tubes, there to be
reconverted into steam.
The con-
The relation between the heat receiving and heat delivering surfaces, as well as
the quantity of liquid to be contained in the tubes or vessels intended for heat
transmission have to be calculated so as to constantly maintain the equilibrium
between the quantity of heat absorbed per unit of time and the quantity of heat
delivered.
The accompanying drawing shews a vertical section of an evaporating apparatus
arranged according to this invention.
As shown A is the furnace with a horizontal and stepped grate a a¹, feed hopper a*
and gas passages a' leading to the flue a*. BB are the boilers, connected with
each other and partly filled with the liquid to be evaporated.
The said boilers, as well as the furnace, may be of any known construction.
In the bottoms 6 of the boilers B a number of tubes.C are strongly secured by
means of tapering screw plugs 6', the upper ends of the said tubes projecting into
the boilers B and being entirely or partly surrounded by the liquid to be evaporated,

page_text: while their lower parts pass through the bottoms of the boilers and the roof D of
the furnace which entirely separates the boilers from the lower ends of the tubes,
that are exposed to the immediate action of the hot combustion gases.
Before fitting the heat-transferring tubes C into the boilers and the furnace the
tubes are charged with a small quantity c of water shewn in the part of the drawing
representing one of the tubes in partial section, the amount of which water is
previously determined by trials. The tubes then are exhausted of air by heating,
and are closed air-tight at their upper extremities c¹.
When the tubes have been exhausted of air and secured in the position shewn in
the drawing, and the boilers B have been filled with liquid, the lower ends of the
tubes are heated by the furnace and the liquid they contain is partly converted
into steam or vapour, which heats the liquid contained in the boilers B, and finally
evaporates it by direct transmission of heat causing the condensation of the steam
or vapour. The liquid resulting from this condensation then runs down into the
furnace-ends of the tubes and in this manner gives rise to a continuous circula-
tion, the effect of which is to transfer constantly the heat from the furnace to
the liquid which is to be evaporated. When the working of the apparatus
is stopped, the steam or vapour in the tubes is totally condensed and the
liquid thus recovered is ready for work in the described manner on the furnace
being reheated.
Trials have shown that evaporating appliances provided with these heat-
transferring tubes, as compared with similar appliances hitherto in use, will
require under like conditions only one-fourth of the dimensions of the directly
heated surfaces, so that the cost of erection will be considerably diminished, as
will also that of working, owing to the saving of losses of heat by transmission
and radiation and to the greater conductivity of the steam or vapour.
It is obvious that this system is applicable as well to cooking apparatus as
to boilers, hot-water heating plant, etc. for cooking, distilling and steam-producing
purposes.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In apparatus for heating liquids and producing steam or vapour, effecting
the transmission of heat from the generator of heat to the liquid which it is
required to heat or to evaporate, by means of steam under pressure by sub-
mitting to the immediate action of the source of heat, a small quantity of liquid
contained in hermetically closed tubes, the resulting steam or vapour being
made to rise within these tubes to a place secluded from the action of the
Bource of heat, where, in consequence of direct transmission and of condensation,
it abandons its heat to the liquid which it is intended to heat or to evaporate,
the quantity of liquid contained within each tube being so proportioned as to
avoid any overheating of the steam or vapour produced from it, substantially as
.described.
2. Evaporating or heating apparatus wherein air exhausted and hermetically
closed tubes C partly filled with liquid have their one end projecting within a
furnace A, while their opposite end projects into receivers or vessels B which
are entirely separated from the furnace and contain the liquid to be heated or
evaporated, substantially as described with reference to the drawings.
Dated this 23rd day of January 1893.
ABEL & IMRAY,
Agents for, the Applicant.