IMPROVEMENTS IN PYROMETERS
Year: 1883

page_text: LETTERS PATENT to Alfred Longsdon of New Broad Street in the City of
London for an Invention of "IMPROVEMENTS IN PYROMETERS" communicated
to him from abroad by Alfred Krupp of Essen in the Empire of Germany
Cast Steel Manufacturer
PROVISIONAL SPECIFICATION left by the said Alfred Longadon at the
Office of the Commissioners of Patents on the 6th April 1883.
ALFRED LONGSDON of New Broad Street in the City of London " IMPROVE-
MENTS IN PYROMETERS" (A Communication to me from abroad by Alfred Krupp
of Essen in the Empire of Germany, Cast Steel Manufacturer)
This invention consists in improvements on the invention described in the
Specification of Henry Hobson's Patent N° 1271 dated 5th April 1873; that
invention consisted in an apparatus for ascertaining the temperature of hot air or
gases and especially that of hot air blast; the apparatus was in the form of a kind
of injector into which the hot blast entered under the pressure in the blast heating
apparatus the jet of hot blast inducing a current of cold air from without and
commingling therewith. The temperature of this mixture of hot and cold air was
read off on an ordinary thermometer and was intended to determine the
temperature of the hot blast.
The defects in this apparatus are: that it takes no account whatever either of
the temperature of the induced cold air or of the pressure under which the hot
blast enters.
The object of this present invention is to obviate the defects stated. For this
purpose the apparatus is provided with an appliance whereby it is enabled to work
with a constant pressure; this appliance consists in a reducing valve or cock and
a quicksilver or other pressure gauge, the valve being so set or regulated according
to the gauge that the pressure of the hot blast entering the apparatus, is kept
lower than the pressure in the air heating apparatus from which the hot blast is
supplied. The apparatus is also provided with a thermometer for specially
indicating the temperature of the cold air which is induced into the apparatus by
the hot blast. By noting the difference between the indication on the thermometer
Die R1

page_text: for the mixture of the hot and the cold air, and the indication on the thermometer
for the cold air and by multiplying this difference with a constant coefficient which
depends upon the area, proportion and position of the two tuyeres and which is
found by experiment with the apparatus it is ascertained by how much the
temperature of the hot blast exceeds that of the induced cold air.
By means of a sliding graduated index on the cold air thermometer which index
is constructed on the basis of the coefficients found, and the zero of which is
made the temperature indicated by the other thermometer, this difference of
temperature may be read off easily.
Or the apparatus may, vice versa be used so that the cold air induces the hot
air. The thermometer for the cold air is then inserted in the cold air entering
the apparatus.
The apparatus may also be made in a portable form and for this purpose be
provided with a handle of a bad heat conducting material.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Longsdon in the Great Seal Patent Office on the 3rd October
1883.
ALFRED LONGSDON of New Broad Street in the City of London "IMPROVE-
MENTS IN PYROMETERS." (A communication to me from abroad by Alfred Krupp
of Essen in the Empire of Germany Cast Steel Manufacturer)
This invention consists in improvements on the invention described in the
Specification of Henry Hobson's British Patent No 1271 dated 5th April 1873; that
invention consisted in an apparatus for ascertaining the temperature of hot air or
gases and especially that of hot air blast, for Blast Furnaces. The apparatus was
in the form of a kind of injector into which the hot blast entered under the
pressure in the blast heating apparatus, the jet of hot blast inducing a current of
cold air from without and commingling therewith. The temperature of this
mixture of hot and cold air was read off on an ordinary thermometer and was
intended to determine the temperature of the hot blast.
The defects in this apparatus are; that it takes no account whatever either of
the temperature of the induced cold air, or of the pressure under which the hot
blast enters In order to fix the temperature of the hot air one of the constituent
parts of the mixture of the hot air and the cold air in the apparatus, it is obvious
that the temperature of the other constituent, viz: the cold air must be known.
It is also clear that according as the pressure varies under which the hot blast
blows into the apparatus so will the amount vary of the drawn in cold air and
thus the proportion of hot and cold air in the mixture, and that therefore also with
the same temperature of the hot blast the temperature of the mixture must change
with the pressure of the hot blast. Many experiments made by the inventor have
also confirmed that the varying pressures, under which the hot wind is blown in,
do lead to materially different results.
The object of this present invention is to obviate the defects stated. For this
purpose the apparatus is provided with an appliance whereby it is enabled to work
with a constant pressure; this appliance consists in a reducing valve or cock and a
quicksilver or other pressure gauge, the valve being so set or regulated according
to the gauge, that the pressure of the hot blast entering the apparatus is kept lower
than the pressure in the air heating apparatus from which the hot blast is supplied.
The apparatus is also provided with a thermometer for specially indicating the
temperature of the cold air which is induced into the apparatus by the hot blast.
By noting the difference between the indication on the thermometer for the mixture
of the hot and the cold air, and the indication on the thermometer for the cold air,
and by multiplying this difference with a constant coefficient which depends upon
the area, proportion, and position of the two tuyers and which is found by
experiment with the apparatus, it is ascertained by how much the temperature of
the hot blast exceeds that of the induced cold air.
By means of a sliding graduated index on the cold air thermometer, which index
is constructed on the basis of the coefficients found, and the zero of which is made
the temperature indicated by the other thermometer, this difference of temperature
may be read off easily.
Or the apparatus, may, vice versa, be used so that the cold air induces the bot
air. The thermometer for the cold air is then inserted in the cold air entering the
apparatus.
The apparatus may also be made in a portable form and for this purpose bo
provided with a handle of a bad heat conducting material.
In the accompanying drawing I have shown the manner of carrying this
Invention into effect.

page_text: Figure 1 is a vertical longitudinal part section, Figure 2 a vertical cross section
on line a a, Figure 3 a plan of the apparatus, and Figure 4 a vertical section
through the pressure gauge forming part of the apparatus or connected therewith.
The hot blast from the heating stoves enters the apparatus at A and is by the
cock H reduced to the desired pressure, which pressure is measured and indicated
on the scale of the quicksilver manometer C. This constant pressure is chosen so
low in order to be sure that it is lower than the varying pressure in the Hot Blast
Stoves. The temperature of the cold air induced through the orifice B is indicated
by the thermometer D, while the temperature of the combined mixture of hot blast
and cold air is indicated by the thermometer C. Or the cold air may be let in
under pressure at A the hot air then entering at B, the position of the thermometer D
being then suitably altered
Having now described the nature of the said Invention and in what manner the
same is to be performed I declare that I claim.
In apparatus constructed on the injector principle and intended for determining
the temperature of hot air or gas the application of means for obtaining a constant
pressure of the entering hot blast and of a thermometer for measuring the
temperature of the drawn in cold air substantially as described and also as
illustrated by the accompanying drawings.
In witness whereof I the said Alfred Longsdon have hereunto set my hand
and seal this twenty seventh day of August in the year of our Lord One thousand
eight hundred and eighty three.
ALFRED LONGSDON
(L.S.)