Note: Descriptions are shown in the official language in which they were submitted.
1334859
METHOD AND APPARATUS FOR THE DETECTION OF LEAKS ON METALLURGICAL
VESSELS
BACKGROUND OF THE INVENTION
~ Field of the invention
- The invention relates in general to metallurgical furnace
leak detection devices and methods, and in particular to a new
and useful method for recognizing leakages on cooling elements in
which the coolant, escaping out of the cooling elements in the
event of a leakage, evaporates.
It is known to line metallurgical vessels with refractory
stone and/or substances. In this arrangement in the regions of
the vessels which are particularly strongly heated (for example
through hot waste gases or as in the case of an electric light
arc furnace through the radiation of the light arc) the
refractory lining is customarily replaced by a duct system or
cooling elements, through which a cooling fluid flows. This
cooling circulation of metallurgical vessels which is subdivided
into individual circles can be a cold-water or a hot-cooling
system with water as cooling liquid. Since, however, not always,
for example in an electric arc furnace due to the liquid metal
2S bath, the refractory lining can be entirely dispensed with. The
lining of many metallurgical vessels consists of a combination of
refractory lined parts and individual cooling elements through
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which a cooling liquid flows, which cooling elements are combined
to form a total cooling circulation consisting of individual
circles.
` When leaks occur at the vessel parts through which cooling
fluid flows, for example at the water-cooled panels of an
electric arc furnace, the cooling fluid or the water penetrates
into the lining below the cooling elements and destroys them
through hydration. As long as these leakages are not recognized
in time destruction of the vessel wall can occur due to the
decomposition of the refractory lining and thus, for example,
penetration of the liquid metal from the melting vessel. This
leads, as a rule, to costly damages of the metallurgical vessel
as a consequence.
Leaks of relatively large size of the cooled vessel parts,
for example cooling elements, can be determined through
measurements and monitoring of the through flows. To this end,
the total cooling circulation is usefully subdivided--into
individual circles and potentially occurring - leakages--are ----
registered with through flow measurements in these individual
circles. The lower limit of leak recognition by through flow
measurement with the currently available equipment is L
approximately 250 cm3/seconds. Measurement technology, thus,
permits recognition of good-sized leaks. These are then
announced to the operating personnel. Beyond the measurement
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itself it is then necessary to equip each individual circle with
the necessary rapid shut-off devices in order to be able, in the
event of failure, to shut off individual cooling regions in the
fore-run as well as the back-run to prevent further running out
of the cooling liquid.
Small leaks, for example in the form of a few drops/min
could not be recognized until now.
SUMMARY OF THE INVENTION
According to the invention, a method for cooling the liquid
escaping form the cooling elements and vaporizing is collected as
vapor, led to a moisture indicator and recorded.
As arrangement suitable for carrying out the method
according to the invention is characterized in that in the
vicinity, preferably below the ducts or cooling elements of the
metallurgical vessel, a pipe system is installed constructed of
perforated pipes as vapor collection pipes which comprises at
least one perforated pipe closed on one end whose other end is
brought out and connected to a moisture indicator.
Even small amounts of liquid which escape from the cooling
elements in the event of a leak and penetrate into the refractory
lining of a metallurgical vessel vaporize due to the high
temperature of the re~ractory stone or substance. The volume
` 133~859
increase in the vaporization generates excess pressure in the
refractory lining which leads to a collection of vapor in the
perforated collection pipes or removal pipes. The excess
pressure in these pipes drives the vapor through a relief bore
5~ which is at the pipe end outside the metallurgical vessel on
which the moisture indicator is attached. In the process the
vapor condenses on the moisture indicator and based on the
corresponding reaction triggers an electrical signal.
According to this method and with the aid of the arrangement
suitable for carrying out the method it is possible to detect
even small leaks of metallurgical vessels which operate with a
wall temperature greater than approximately 100~ C. Essential is
the vaporization of the cooling liquid penetrating from a leak.
Regarding measuring accuracy, for example, moistening the
refractory lining of an electric arc furnace with only 1 cm3 of
water yielded unmistkable proof with the arrangement according to
the invention. _
Accordingly it is an object of the invention to provide an~~
apparatus for detecting leaks in the cooling system of the walls
of a cylindrical metallurgical furnace which is lined with
refractory and which comprises placing at least one perforated L
collection pipe around at least a portion of the furnace in a
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position below the cooling system and such that it defines a
vapor collection duct having an exterior end, and a moisture
indicator adjacent to exterior end.
A further object of the invention is to provide a device for
detecting leaks in a metallurgical furnace which is simple in
design, and rugged in construction, and economical to
manufacture.
The various features of novelty which characterize the
invention are pointed out with particularity in the claims
annexed to and forming a part of this disclosure. For a better
understanding of the invention, its operating advantages and
specific objects obtained by its uses, reference is made to the
accompanying drawings and descriptive matter in which preferred
embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings
Figure 1 is a top view of an electric arc furnace; and
Figure 2 is a partial section of an electric arc furnace.
GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS
3S
Referring to the drawings in particular the invention
embodied therein comprises an apparatus for detecting leaks in
the cooling systems of the walls of a cylindrical metallurgical
furnace generally designated 1 which includes a lining or
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refractory material 2 and walls which have cooling ducts 3
forming the cooling system along with further ducts 8. In
accordance with the invention at least one vapor collection pipe
is arranged in a position below cooling elements 3 and 8 extend
C around at least a portion of the furnace in a position to collect
vapor in one or more ducts which have exterior ends with moisture
indicators 6.
Below the cooling elements 3 the vapor collection pipe 5 is
installed. This is, for example a commercially available thick-
walled 1/2 inch pipe which receives perforations of a diameter of
S mm on its underside. The perforations are arranged at a
distance of, for example 100 mm. The perforations on the
underside of the vapor collection pipe 5 has the advantage that
the perforations are protected from becoming clogged by
refractory material which may fall down from the walls.
Figure 1 indicates that the leakage detection system is
subdivided into six individual sections--a -to f -distributed~
uniformly on the circumference--of--the -furnace--vesse-l~=1.- Each=~ -~-
system functions independently of the other.
The subdivision of the leak measuring system into several
sections has the advantage that a potential leak can be localized
more rapidly. The measuring system, consequently, also has
greater response sensitivity.
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At the exit of each vapor collection pipe 5 closed on one
side the moisture indicator 6 is located outside the furnace
vessel 1 which is a commercially available measuring apparatus
which functions for example so that the moisture indicator reacts
to changes of electrical resistance. The resistance change is,
thus, a measure of the moisture. If a given resistance value is
exceeded an optical or acoustical signal is triggered so that the
furnace operating personnel can react. The measured values of
the moisture indicator can, of course, also be registered on
measuring strips.
In Figure 2 leaks in the cooling system 3 are indicated. A
leak 7 due to wear is indicated on a cooling element and another
leak 8 is on a cooling means duct connection which has become
leaky.
The cooling liquid escaping from the leaks 7 and 8 runs or
drips down and turns into vapor due to high temperatures
obtaining there which collects in the vapor collection pipes 5.
In the pipes excess pressure obtains so that this pushes the
vapor in the direction of the moisture indicator 6 in which the
vapor condenses and from which upon exceeding a given limit value
a reaction, i.e. an acoustical or optical signal is triggered.
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The leak detection system according to the invention can be
applied on all metallurgical vessels which are lined with
refractory material and equipped with cooling elements.
Subsequent installation into metallurgical vessels is possible.
"
While specific embodiments of the invention have been shown
and described in detail to illustrate the application of the
principles of the invention, it will be understood that the
invention may be embodied otherwise without departing from such
principles.
