Means and Method for Heating Air or Gases.
Year: 1898

page_text: Date of Application 3rd Nov
1898
Complete Specification Loft 23rd June 1800 Accented 2nd Nov
1900
Complete Specification Left 23rd June 1800 Accepted, 3rd
Nov
1900
PROVISIONAL SPECIFICATION.
Means and Method for Heating Air or Gases.
I, HERMANN NIEWERTH, of 134A, Potsdamer Strasse, Berlin, Germany,
Metallurgist, do hereby declare the nature of this invention to be as follows:-
In metallurgical operations, such as for instance blast furnace working, steel
castings and in many other industries, it is of importance to have the blast
or air for combustion of as high a temperature as can be obtained, partly for
the sake of economy in working, and partly for the purpose of attaining the
requisite high temperatures.
For the attainment of this object it is now the almost universal custom to use
large chambers filled with fire resisting stones through which chambers the
hot gases of combustion pass and heat the stones; the first of such chambers
being heated, the gases are made to pass into a second chamber whilst the air of
blast or gas, that is to be heated is passed through the first chamber, so as to take
up the heat stored up in the said first chamber and thereby to be raised to the
requisite temperature.
On the first chamber becoming cooled, the path of the blast is changed to
pass through the second chamber that has meanwhile become hot, and the gases
of combustion are again led through the first chamber to reheat the stones in same.
One defect of this system now in almost universal use is that the dampers and
valves are all exposed to the heat and hence quickly wear and soon become de-
fective in operation. Such apparatus are morcover very expensive to lay down,
require much space, frequently require to be repaired and for working the same
very expert workmen must be employed. Furthermore the utilization of the
heat is relatively small.
Another system at present used in some cases is so arranged that the hot
gases are made to pass round fire clay tubes or pipes the gases to be heated
passing through the said pipes. This system does not find much favour because
the utilization of the heat thereby is still less and the pipes or tubes easily
break, which makes the system unreliable.
My improvements are intended to obviate all these defects. My blast heating
apparatus takes up very little room is certain in operation, requires no
setting, and utilises the gases of combustion in a high degree. According to
my method I arrange a series of heating furnaces and pass into same fine sea
sand which is heated by the gases passing over it. In practice it will be
convenient to arrange several such furnaces above one another and the sand
is permitted to fall into the topmost by means of any suitable apparatus. The
sand heated to a certain degree in the topmost furnace, then falls from the
first into the second furnace, here it takes up more heat then from the second
into the third furnace and so on, until the sand has attained the desired tem-
perature.
Under the last furnace there is a cylinder furnished with terrace like steps or
off sets upon which the hot sand falls from the last furnace. Within this
cylinder the sand flows from one step to the other and finally reaches the bottom

page_text: of the apparatus whence it passes outward. The gas to be heated is introduced
from below into the cylinder passes over the hot sand and through the falling
sand, whilst it is dropping from one step or off set to the other, is heated more
and more and finally is taken off at the top of the cylinder in a highly heated
condition for use.
66
"
The sand passing out is by suitable means raised again and introduced into
the first furnace, and again passes through the process hereinabove described.
The fine sand will not cake even at the highest temperatures to be used
in this process or occurring therein but on the contrary flows over inclined
surfaces so easily and exactly as to permit its being led thro' a predetermined
path almost as easily as water. The passage from one furnace to the next and
from the furnaces to the stepped cylinder can therefore be easily arranged and
acts with certainty.
The transmission of heat from the hot sand particles to the gases flowing round
the same, takes place easily and to a higher degree than can be attained by any
of the present known methods, sand being very absorbent of heat. It is clear
that no more favourable conditions can be imagined for the purpose than a rain
of sand which absorbs and gives up heat. Various forms of furnaces reverberatory
or other, can be used for the purpose as also the cylinder with cascades steps or
sets off" for heating the gases. Instead of sand, granulated fire clay may
be used or other suitable material. In some cases coal dust may be used instead
of sand, or mixed with sand.
66
Dated this 3rd day of November 1898.
FREDERIC PRINCE,
Agent for Applicant.
I, HERMANN NIEWERTII, of 134A, Potsdamer Strasse, Berlin, Germany,
Metallurgist, 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:-
In metallurgical operations, such as for instance blast furnace working, steel
castings, and in many other industries, it is of importance to have the blast
or air for combustion at as high a temperature as can be obtained, partly for
the sake of economy in working, and partly for the purpose of attaining the
requisite high temperature.
For the attainment of this object, it is now the almost universal custom to use
large chambers filled or packed with blocks or pieces of fire resisting material.
Through these chambers the products of combustion are caused to pass, and
heat the fire resisting or refractory material. One of such chambers being heated,
the gases are then made to pass into a second chamber, whilst the blast air or gas
that is to be heated is passed through the first chamber, so as to take up the
heat stored up in the said first chamber, and thereby to be raised to the requisite
temperature.
On the first chamber becoming cooled, the path of the blast air is changed and
caused to pass through the second chamber that has meanwhile become hot, and
the gases of combustion are again led through the first chamber to reheat the
refractory material therein.
One defect of this well known system is, that the dampers and valves are all ex-
posed to the heat, and hence quickly wear, and soon become defective in operation.

page_text: Such apparatus is moreover very expensive to lay down, occupies much space,
frequently requires to be repaired, and calls for the employment of very expert
workmen. Furthermore the utilization of the heat is relatively small.
Another system at present used in some cases, is so arranged that the hot
gases are made to pass round fire clay tubes or pipes, the blast air or gas
to be heated passing through the said pipes. This system does not find much
favour, because the utilization of the heat thereby is still less than with the
apparatus previously described and the pipes or tubes easily break, which makes
the system unreliable.
My improvements are intended to obviate all these defects; my blast heating
apparatus as hereafter described takes up very little room, is certain in operation,
requires no setting and utilizes the heat from the gases of combustion in a high
degree. According to my invention I arrange a series of heating furnaces, and
pass into same a suitable quantity of fine sea sand which is heated by the gases
of combustion passing over it. In practice it will be convenient to arrange
several such furnaces above one another, and the sand should be permitted to
fall into the topmost by means of any suitable apparatus. The sand when heated
to a suitable degree in the topmost furnace, is then allowed to fall from the
first into the second furnace, here it takes up more heat, then from the second into
the third furnace and so on, until the sand has attained the desired temperature.
The sand having been thus heated is delivered to an apparatus, now about to
be described, wherein the heat obtained by the sand is given up to the air or
gas which is to be employed for the blast, hereafter termed blast air.
In order that such apparatus may be readily understood I will describe same
with reference to the accompanying drawings, whercon Fig. 1 is a transverse and
Fig. 2 a longitudinal section of the apparatus.
The apparatus comprises a hollow rectangular structure A, of refractory
material (or it may be of cylindrical formation) and the upper part is provided
with a hopper B, through which hopper the sand is delivered from the last
furnace into the top part of the structure A.
Within this structure A, the sand-indicated by dots-flows by gravity from
one horizontal division C to the next and so on and finally reaches the bottom of
the apparatus A, where it is passed outwards, for example, by the carrier screw D.
In the construction shewn each horizontal division C extends entirely across
the structure and is formed of two plates e, f, the upper plate e, being formed
with slotted holes e¹, extending almost entirely across the structure and it is
through these holes that the sand passes while the plate f, is arranged at a
short distance below the plate e, and is formed with slotted holes fl of greater
width than the slotted holes e¹ of the plate e, but so arranged that the holes f¹,
do not come immediately below the holes e¹, the object of such an arrangement
being to prevent the draught of air passing as hereafter described between the
horizontal divisions C, interfering with the downward passage of the heated
sand.
It will now be understood that the sand from the hopper gradually passes
downwards, falling through one division C, and through the next lower division C,
and so on from floor to floor until it reaches the base, from whence it is removed
for re-heating.
Into such a structure A, the blast air to be heated is introduced at the
lower part, as by the passage E, passes beneath the lower division C, is conducted
by a passage F, formed in the wall of the structure, to the next higher space
between the divisions, from whence it is conducted by a passage G, in the
opposite wall of the structure to the next higher space between the divisions and
so on upwards until it is delivered in a highly heated state by a passage H.
Throughout its passage between the divisions C, the blast air passes over the
hot sand and through the falling sand, taking the heat therefrom, becoming
heated more and more and is finally delivered from the said passage H, in a
highly heated condition.

page_text: In some cases it may be found desirable or convenient to subject the sand to
the action of heat as it passes from the hopper B, into the receptacle A, and this
may readily be effected, as is shewn at Figs. 1 and 2, by increasing the number
of divisions C, and passing the heated products of combustion from a furnace
through a passage such as J, causing the products of combustion to pass in a
circuitous manner between those divisions C, which are above the series forming
the blast air passage and so that the products of combustion travelling in
the direction of the arrows find their exit by the passage K.
Thus the falling sand passing from the hopper is heated or re-heated before
it reaches those divisions between which the blast air is passing.
6
The sand passing out at the base of the apparatus can be again heated, and
again passed through the apparatus and I have found that the fine sand will not
cake even at the highest temperatures which may be needed in the process,
but will flow so easily and exactly as to admit of its passing almost as easily
and smoothly as water.
The transmission of heat from the hot sand particles to the blast air flowing
round same, takes place easily and with greater effect than can be attained by
any of the present known methods, sand being very absorbent of heat.
Any convenient and well known forms of furnaces can be employed for the
purpose of heating the sand preparatory to its being placed in the hopper and
also as explained, the sand may be heated during the first part of its passage
through the receptacle A. Instead of sand, granulated fire-clay may be employed
or other suitable material, and in some cases coal dust may be used instead of
sand or mixed with sand.
:
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what
I claim is:-
A process for heating air or other gases, consisting in causing heated sand
or other finely granulated material to pass through closed chambers, through
which also the air or gases to be heated are passed, the heated refractory material
yielding up its heat to the said air or gases to be heated.
патой this 2nd dose of Luna
VIO
Liated the 2nd dow
FREDERIC PRINCE,
37, Cursitor Street, Chancery Lane, London,
Agent for Applicant.