Improvements in or relating to Cooking by Steam.
Year: 1897

page_text: Date of Application, 24th Mar., 1897
Complete Specification Left, 28th July, 1897-Accepted, 19th Mar., 1898
VA
Improvements in or relating to Cooking by Steam.
I, HUBERT HIGGINS, of 4, Trinity Street, Cambridge, in the County of Cambridge,
Demonstrator of Anatomy to the Cambridge University, do hereby declare the
nature of this invention to be as follows:-
The object of this invention is to provide an improved method of, and apparatus
for cooking food by means of steam, whereby in the same apparatus, steam may be
employed at a temperature of about 2120 Far. or at any desired temperature above
that point, the steam in all cases being kept substantially at atmospheric pressure.
In the method of steam cooking generally in use the food is placed in a chamber
or chambers into which the steam is introduced at a greater or less pressure. In
most cases no provision is made to avoid condensation of the steam (the food thereby
becoming wet), and in cases where temperatures above 212° Fh. are employed,
cumbersome and expensive chambers are necessary in order to resist the high pres-
sure, which is a source of inconvenience, and even danger in unskilled hands.
In no case are means provided to regulate the temperature of the cooking cham-
ber to suit the requirements of different cooking, roasting and baking operations
necessitating varying degrees of heat.
The apparatus employed in carrying out this invention consists of one or more
cooking chambers, a steam generators and a steam superheater with the necessary
heating apparatus and if desired auxiliary superheaters.
The cooking chamber consists of an inner chamber of suitable size and materia!
provided with shelves and is completely surrounded by an outer chamber of some-
what larger size, forming what is commonly known as a jacket. Proper provision
is made for doors and all necessary connections and fittings for supplying and
carrying away the steam and the jacket may be suitably lagged to economize heat.
Any suitable steam generator may be employed. It is furnished preferably
with two connections to the cooking chamber: one, direct for use when steam at
about 212° Fh. is employed; the second through the superheater, which may
be of any convenient kind and heated in any suitable manner but is so arranged
that either the whole or a part of it may be used at will for the purpose of regu-
lating the temperature of the steam.
In order to prevent condensation of steam in the cooking chamber the jacket
is heated either (a) by passing through it the whole or a sufficient proportion of
the combustion gases from the heating apparatus of the boiler or superheater; or
(b) by the direct application of heat to the exterior of the jacket; the heat supply
being under control, and the necessary pipes, dampers etc., being provided in
each case for the circulation of the hot air or gases.
Two or more cooking chambers may be used and the steam passed from one to
the other; a superheater being provided between each chamber if desired.
All necessary valves, gauges, and fittings are provided for properly working
and controlling the apparatus.
When in operation a continuous current of steam at substantially atmospheric

page_text: pressure is maintained through the chamber at a temperature regulated to the degree
of heat required for the proper carrying out of any desired culinary process, the
jacket being meanwhile maintained at a temperature so as to prevent conden-
sation.
Improvements in or relating to cooking by Steam.
I, HUBERT HIGGINS, of 4, Trinity Street, Cambridge, in the County of Cambridge,
Demonstrator of Anatomy to Cambridge University, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:-
The object of this invention is to provide an improved method of and apparatus
for cooking food by means of steam, whereby in the same apparatus, a constant
current of steam may be employed at a temperature of about 100° C., or at any
temperature above that point desirable for the purposes above mentioned; the steam
in all cases being kept substantially at atmospheric pressure."
In the method of steam cooking generally in use the food is placed in a cham-
ber or chambers into which the steam is introduced at a greater or less pressure.
In most cases no provision is made to avoid condensation of the steam (the food
thereby becoming wet), and in cases where temperature above 100° Fh., are em-
ployed, cumbersome and expensive chambers are necessary in order to resist the
high pressure, which is a source of inconvenience, and even danger in unskilled
hands.
In no case are means provided to regulate the temperature of the cooking cham-
ber to suit the requirements of different culinary operations, such as cooking,
roasting, and baking, necessitating varying degrees of heat.
The apparatus employed in carrying out this invention comprises a chamber
and a steam superheater, with the necessary heating apparatus and steam gener-
ator.
The accompanying drawing shows diagrammatically à chamber and superheater
constructed according to this invention. It is arranged to cook with steam at
atmospheric pressure but it is evident that by putting a lightly loaded valve at
the orifice it can be made to work at somewhat above that pressure if it is found
more convenient. But whatever be the pressure fixed upon for that purpose the
temperature at which the cooking is done is still in the control of the operator as
by means of the superheater he can raise it to any desired extent above the tem-
perature of saturated steam at that pressure.
The chamber consists of an inner chamber A preferably completely surrounded
by an outer chamber B of somewhat larger size forming what is commonly known
as a jacket.
The chamber A may be of any suitable size and material, and provided with
shelves or other fittings according to the purpose for which it is intended, such
as cooking, drying or sterilizing. Proper provision is made for doors and it is
connected by the pipe D with the superheater C, a pipe A¹ being likewise provided
for carrying away the steam..
The superheater may be of any ordinary construction that gives a travel of the
desired extent to the steam and is provided with openings, controlled by valves,
at various portions of its length, so that the steam can be withdrawn at will after

page_text: a greater or less exposure to the heating medium. A convenient form consists
of a coil, as shown at C, receiving its steam through the valve C, and having
openings, controlled by valves C2, C3, C, C, into the pipe D connected with the
chamber A.
The coil may be of any convenient form, either helical as shown or consisting
of zig-zag or parallel tubes united by return bends and may be of varying cross
section and calibre the essential point being the faculty of controlling the length
of travel of the steam when exposed to the heating medium. Four connections
are shown as a convenient number, but more or less may be used according to the
range of temperature which it may be desired to employ in the chamber. Ill
case the heating medium is liquid or gaseous an equivalent regulation may to some
degree be obtained by varying the heating power.
The superheater may be heated in any convenient manner, either directly by a
gas or other furnace, or by the products of combustion from the generator furnace.
The supply of steam to the superheater may be obtained in any convenient man-
mer, for instance from a generator forming part of the apparatus, and which may
be either an ordinary boiler or a special arrangement, as for instance a tube or
system of tubes, part forming the generator and part the superheater, in which
case the steam is produced at or about atmospheric pressure.
In order to prevent condensation of steam within the chamber A, it may be
provided with a jacket B, heated either (a) by passing through it the whole or a
sufficient proportion of the combustion gases from the heating apparatus of the
boiler or superheater, or (6) by the direct application of heat to the exterior of the
jacket or (c) by passing a current of steam from the superheater through the jacket
previous to the introduction of steam into the chamber. The necessary pipes,
dampers, etc., are provided in each case so that the temperature is under control
and the outer wall of the jacket is preferably lagged.
The pipe D may be connected direct with the steam supply by a valve 1', so
that if desired steam may be passed through the chamber without first passing
through the superheater. In this way if desired the resulting temperature of the
cooking steam may be varied independently of the regulation of the superheater.
All necessary gauges, pyrometers, and fittings are provided for properly working
and controlling the apparatus.
Two or more chambers may be used and the steam passed from one to the other,
a superheater being provided between each chamber if desired. When a series
of several chambers is employed the necessary connections are provided so that
any one chamber can be disconnected without stopping the circulation of steam
through the rest of the series.
When in operation the jacket B is first heated so as to warm the chamber A
and prevent condensation on the initial admission of steam therein, and this heating
may be continued throughout the operation if desired.
Steam having been admitted to the superheater C through the valve C', one of the
cocks C², C, C4, C5, is opened and a continuous current of steam passes into the
chamber A through the pipe D, escaping therefrom by the valve A. According
as the temperature is required to be raised or lowered the steam is allowed to
travel through a greater or less length of the superheater. If a temperature is re-
quired only slightly in excess of 100° C., the cock C, is opened and the steami
passes through only a short portion of the superheater before entering the cham-
ber A through the pipe D. To raise the temperature the cock C³ is opened and C²
closed, giving the steam a longer exposure to the heating medium, the highest
temperature being obtained by passing the steam through the whole length of the
superheater by opening the cock C, the others being closed. By this means a perfect
control of the temperature within the chamber is obtained.
The temperature is still further capable of being raised by passing a large
volume of steam through the superheater and allowing it to be carried off by an
orifice of suitable size in the chamber (this does not materially increase the pres-
sure in the chamber).

page_text: Having now particularly described and ascertained the nature of this said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
1. In steam cooking apparatus the use of a superheater to enable the temperature
of the cooking steam to be varied without thereby necessitating a change of
pressure.
2. In steam cooking apparatus the use of steam at fixed (and preferably atmos-
pheric pressure but at varying temperature such temperature being obtained by
means of a superheater and regulated as herein described.
3. In steam cooking apparatus the combination of a jacketted chamber and a
superheater capable of regulation substantially as described.
4. In steam cooking apparatus a superheater such as C provided with branches
controlled by valves substantially as and for the purpose described.
5. The complete steam cooking apparatus substantially as described and illus-
trated.
BOULT & WADE,
Agents for the Applicant.