Metallurgical apparatus – With means treating or handling gases exhausted by treating... – By means recycling exhaust gas
Reexamination Certificate
2000-06-21
2002-12-17
Kastler, Scott (Department: 1742)
Metallurgical apparatus
With means treating or handling gases exhausted by treating...
By means recycling exhaust gas
C266S144000, C432S019000
Reexamination Certificate
active
06495092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combustion apparatus and a melting furnace, which includes a continuous furnace and a batch-type furnace, for melting nonferrous metals such as copper, aluminum, zinc and alloy, which comprises more than one pair of regenerative burners where waste heat produced by a first burner is stored in a regenerator of a second burner and the stored waste heat is utilized when the second burner is fired.
2. Description of the Related Art
There has been a combustion apparatus for melting and heating metals. The apparatus comprises a regenerative burner including a pair of burners
19
,
20
. The burners
19
,
20
are fired alternately as such that when a first burner
19
is fired, a second burner
20
stores waste heat produced by the first burner
19
, and the stored waste heat is used to preheat the combustion air of the burner
20
when the second burner
20
is fired. As illustrated in
FIG. 6
, the conventional combustion apparatus comprises one regenerator
21
or
22
per one burner
19
or
20
, so that, for example, when there are provided eight (four pairs of) burners, the same number, eight, of regenerators need to be installed.
As illustrated in
FIG. 7
, the conventional combustion apparatus comprises a regulating valve
23
at the upper stream of the regenerator
3
for controlling a volume of combustion air. With an operation of the regulating valve
23
, the combustion of the burner
19
or
20
is to be controlled.
Conventionally, there has been a melting furnace for nonferrous metals having a regenerative burner. The regenerative burner comprises a pair of burners, each of which is fired alternately as such that when a first burner is fired, a second burner stores waste heat produced by the first burner. The stored waste heat is used to preheat the combustion air of the second burner when the second burner is fired.
The conventional melting furnace for nonferrous metals will be described in detail referring to
FIGS. 8 and 9
. The melting furnace comprises a pair of regenerative burners
16
,
17
, at the side wall
5
a
of the furnace casing
5
, and each burner
16
or
17
is integrated with a regenerator. This melting furnace operates as such that while a first burner
16
is fired, a second burner
17
is unfired but stores the waste heat produced by the first burner
16
, as the waste heat is exhausted through a regenerator of the second burner
17
. And, when the second burner
17
is fired, combustion air is provided through the regenerator of the second burner
17
and is preheated by the stored waste heat. By use of the waste heat, a thermal efficiency of the burners
16
,
17
increases.
However, in the conventional combustion apparatus, each burner
19
or
20
is equipped with its own regenerator
21
or
22
, so that when a large number of burners
19
,
20
require to be installed in, for example, a continuous furnace
18
, the same number of regenerators
21
,
22
should also be installed. Therefore, the conventional combustion apparatus requires a much installation space as well as much cost and labor for an installation of the regenerators
21
,
22
and a maintenance engineering thereof.
Further, according to the conventional melting furnace for nonferrous metals, each burner
16
or
17
is integrated with its own regenerator and is installed in the side wall
5
a
of the furnace casing
5
. Therefore, an installation space and size of the burners
16
,
17
becomes restricted, and as a result of this, a quantity and capacity of the burners
16
,
17
are also restricted. Besides, it becomes necessary to enlarge the furnace casing
5
in its size, which induces a higher construction cost.
That is, if the conventional melting furnace is provided with a metal feeding device
14
for feeding aluminum, e.g., as well as an auxiliary apparatus
15
, for example a pump, for circulation of the liquid metal at the side wall
5
a
of the furnace casing
5
, in addition to the burners
16
,
17
combined with the regenerators, an installation space of the burners
16
,
17
is severely restricted. This becomes crucial when the furnace casing
5
is smaller in size. In such a case, it becomes necessary to select limited types of burners among many to install in the restricted small installation space. Also, a number of the burners to be installed is restricted. As a result of this, the burners
16
,
17
tend to become unsatisfactory in capacity for efficiently melting and heating the nonferrous metal held in the furnace.
In order to resolve such drawbacks, it is desirable to enlarge the furnace casing
5
in size for broadening the installation space. However, this will bring a new drawback that the construction cost would over exceed.
Further, since the conventional melting furnace for nonferrous metals comprises the burners
16
,
17
at the side wall
5
a
of the furnace casing
5
, when the burners
16
,
17
are fired, the combustion gas runs onto the surface of the liquid metal
40
in the nearly horizontal angle. Thus, the combustion gas does not wide spread over the surface of the liquid metal
40
, heating only a local area of the surface. Besides, the jet flow of the combustion gas impinges on a certain area of the side wall
5
a
of the furnace. The certain area of the side wall
5
a
, where the jet flow of the combustion gas impinges on, becomes extremely high in temperature and a mass of nonferrous metal oxide
30
is produced thereabout and is ingrained and accumulated to the side wall
5
a
. Because of a mass production of the nonferrous metal oxide
30
, the yield of melting decreases. At the same time, as the combustion gas impinges on the side wall
5
a
where the oxide has been accumulated, an operation life of the side wall
5
a
shortens and thus a maintenance cost thereof arises.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a combustion apparatus comprising one regenerator per a plurality of burners in order to save a installation space of the burners. It is also an object of the present invention to provide a combustion apparatus comprising an air regulating valve at each burner in order to individually control a combustion volume of each burner.
It is another object of the present invention to provide a melting furnace for nonferrous metals comprising burners combined with regenerators on the roof of the furnace in order not to restrict the size, disposition and installation space of the burners, which will increase a heat transfer efficiency, save a construction cost and a production of oxide as well as an increase in a life duration of the side wall
5
a
and a reduction of maintenance cost.
A combustion apparatus according to the present invention is characterized in that it comprises a pair or more than two pairs of burner groups. Each burner group comprises one regenerator per a plurality of burners. In each pair of burner groups, a first burner group and a second burner group are fired alternately and waste heat produced when the first burner group is fired is stored in a regenerator of the second burner group. The stored waste heat is utilized to preheat the combustion air of the second burner group when the second burner group is fired. Similarly, waste heat produced when the second burner group is fired is stored in a regenerator of the first burner group, and the stored waste heat is utilized to preheat the combustion air of the first burner group when the first burner group is fired.
The combustion apparatus comprises a regulating valve for controlling a volume of combustion air. The valve is installed on the side of each burner.
A melting furnace for nonferrous metals according to the present invention is used for melting any nonferrous metals and for holding the metal in a liquid form. The melting furnace is characterized in that it comprises a pair or more than two pairs of burner groups. Each burner group comprises one regenerator per a plurality of burners. In each pair of burner groups, a first bur
Hazama Katsumi
Inami Takayuki
Kashima Eiichi
Masuki Keinosuke
Takai Miki
Frishauf Holtz Goodman & Chick P.C.
Kastler Scott
Sanken Sangyo Co., Ltd.
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