U.S. patent number 3,575,581 [Application Number 04/824,975] was granted by the patent office on 1971-04-20 for heat-generating pipe utilizing skin effect current controlled locally in heat generation by short-circuiting bridges.
This patent grant is currently assigned to Chisso Corporation. Invention is credited to Masao Ando.
United States Patent |
3,575,581 |
Ando |
April 20, 1971 |
HEAT-GENERATING PIPE UTILIZING SKIN EFFECT CURRENT CONTROLLED
LOCALLY IN HEAT GENERATION BY SHORT-CIRCUITING BRIDGES
Abstract
In a heat-generating pipe comprising a highly ferromagnetic pipe
and an insulated conductor line inserted therein and having such a
connection that AC flowing through the insulated conductor line is
equal in intensity and opposite in direction to the AC flowing
concentratedly through the inner wall portion of the pipe due to
the skin effect of AC, the heat-generating pipe is characterized in
that a certain section of the inner surface of the pipe is brought
to short circuit state by a conductor line optionally including a
thermostatic or other switch and having an impedance which is
selected according to the requirement for decreasing or elimination
of heat generation in said section, to control the heat generated
in said section.
Inventors: |
Ando; Masao (Yokohamashi,
JA) |
Assignee: |
Chisso Corporation (Osaka,
JA)
|
Family
ID: |
27249138 |
Appl.
No.: |
04/824,975 |
Filed: |
May 15, 1969 |
Current U.S.
Class: |
392/469; 392/478;
219/630 |
Current CPC
Class: |
F24H
1/105 (20130101) |
Current International
Class: |
F24H
1/10 (20060101); H05B 6/10 (20060101); H05b
005/08 () |
Field of
Search: |
;219/10.51,240,241,300,301 ;128/303.12 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Staubly; R. F.
Claims
I claim:
1. In the known type of heat generating apparatus comprising a
length of ferromagnetic pipe, a first length of an electrical
conductor line disposed within said ferromagnetic pipe but
insulated therefrom, and electrical and power connections so that
upon the passage of alternating voltage through said first length
of electrical conductor line there is a concentrated flow of
current along the inner skin of the ferromagnetic pipe to thereby
generate heat in said ferromagnetic pipe, the improvement which
comprises:
a. at least one additional length of electrical conductor line
disposed within said length of ferromagnetic pipe,
b. said additional length of electrical conductor line being
shorter than said first length of electrical conductor line and
arranged generally parallel to at least a portion of said first
length of electrical conductor line,
c. said additional length of conductor line being connected to said
ferromagnetic pipe at two spaced apart points whereby the
concentrated flow of current along the inner skin of the
ferromagnetic pipe is at least partially short circuited along the
inner surface thereof between said two spaced apart points to an
extent dependent upon the impedance of said additional length of
conductor line between said two spaced apart points.
2. A heat-generating pipe according to claim 1 wherein at least one
switchgear is interposed at a position within the short circuit
shunting said inner surface so as to control the heat generation
within said section of said heat generating pipe on an on-off
basis.
Description
This invention relates to heat-generating pipe utilizing a skin
effect of AC flowing through the inner wall portion of a
ferromagnetic pipe such as a steel pipe, which enables to control
heat-generation in a certain section of the inner surface of the
pipe.
When the skin effect is pronounced, the depth of the skin S(cm)
which is an index showing the range of flow of current in a
conductor is represented by a following formula,
S = 5030 .rho./.mu.f (1)
Wherein .rho.(.OMEGA.cm) is resistivity, .mu. is specific
permeability and f is frequency of current per second.
Such a skin effect caused in a ferromagnetic pipe, such as a steel
pipe, will be hereinafter explained by referring to an attached
drawing.
In FIG. 1, an insulated conductor line 1 passes through the inside
of a ferromagnetic pipe 3. One end of the conductor line is
connected to one terminal of AC source 2 and the other end thereof
is connected to one end 4 of the ferromagnetic pipe 3. The other
end 5 of the ferromagnetic pipe 3 is connected to the other
terminal of the AC source 2 by a conductor line 6.
If a relationship represented by the following formula:
T > 2S, D>>S and l>>D (2)
wherein D(cm) is an inner diameter of the steel pipe, l(cm) is its
length, and t(cm) is its thickness, exists between l, D and S, the
current is concentrated on the inner surface of the ferromagnetic
pipe having a large specific permeability, and does not appear onto
the outer surface of the pipe, and such an apparatus can be
utilized as a heat-generating body. This is a publicly known fact
disclosed in Japanese Pat. No. 460,224 (Patent Publication No.
12128/1965) whose counterparts in U.S.A. and Canada are U.S. Pat.
No. 3,293,407 and Canadian Pat. No. 760,556.
In such a heat-generating pipe, it is impossible to decrease or
stop heat generation in at least one section of the pipe, for
example, between X and Y as indicated in FIG. 1.
An object of the present invention is to provide a heat-generating
pipe in which the above-mentioned drawback is overcome, namely, a
heat-generating pipe capable of controlling heat generation in an
optional section of the pipe made of a highly ferromagnetic steel
or the like.
Now, it has been found that the above-mentioned object can be
attained by the apparatus of the present invention.
This invention consists in a heat-generating pipe comprising a
highly ferromagnetic pipe and an insulated electric line inserted
therein and passing therethrough and having such a connection that
AC flowing through the insulated conductor line is equal in
intensity and opposite in direction to the AC flowing only through
the inner wall portion of the pipe due to the skin effect of AC
which is characterized in that a section or plural sections of the
inner surface of the pipe are brought in short circuit state by a
wire or wires having an impedance which varies according to the
requirement for decrease or stoppage of heat generation in said
section or sections, in order to control the heat generated in said
section or sections.
In addition, it is also possible to use with great deal of
advantage the apparatus of the present invention in which a
switchgear is interposed at an arbitrary position within the above
short circuit to realize its on-off cycles, which may be activated
automatically by a thermostat.
The present invention will hereinafter be illustrated with
reference to the attached drawings.
FIG. 1 shows a schematic view of a publicly known heat-generating
pipe utilizing skin effect current, which is given as a reference,
to enable persons skilled in the art to understand the principle
and the construction of the present apparatus.
FIG. 2 shows a schematic, cross-sectional view of a heat-generating
pipe having a short circuit apparatus in a section thereof,
according to the present invention.
FIG. 3 shows a schematic, cross-sectional view of a further
embodiment of the present invention.
In FIG. 2, an insulated conductor line 1 is inserted in and passes
through the inside of a ferromagnetic pipe 3, One end of the
conductor line is connected to one terminal of an AC source 2 and
the other end thereof is connected to one end 4 of the
ferromagnetic pipe 3. The other end 5 of the ferromagnetic pipe 3
and the AC source are connected by a conductor line 6.
Terminals 7 and 8 are provided at both the ends of a section where
heat generation is to be stopped, or controlled, and the section
between both the terminals is shorted by a conductor line 9 having
an impedance much lower than that of the inner surface of the
section of the ferromagnetic pipe. (The section between both the
terminals corresponds to the section between X and Y in FIG. 1.)
Flanges 10 and 12 and covers 11 and 13 are installed for the
convenience of connecting both the ends of the conductor line 9 to
the terminals 7 and 8.
The current from one terminal of an AC source 2 passes through the
insulated conductor line 1 and flows through the inner surface of
the ferromagnetic pipe 3 from one end 4 of the ferromagnetic pipe 3
to the terminal 5 while generating heat, but it passes mostly
through the conductor line 9 during the part from the terminal 8 to
the terminal 7 and flows only through the inner surface of the pipe
3 again from the terminal 7 to the other end 5 of the pipe 3 while
generating heat again; and returns to AC source 2 through the
conductor line 6.
In this case, the current flowing through the insulated conductor
line 1 is almost equal in intensity, and opposite in the direction
of flow, to the current flowing through the conductor line 9, and
there is hardly any skin current occurred in the section of the
pipe between the terminals 8 and 7. Thus, heat generation hardly
occurs in this part.
If the impedance of the conductor line 9 is made larger than that
in the case where the above-mentioned heat generation is almost
stopped, the intensity of the current flowing through the conductor
line 9 becomes smaller than that flowing through the insulated
conductor line 1. In this case, some extent of skin current occurs
in the section of the ferromagnetic pipe between the terminals 8
and 7, and hence some extent of heat generation occurs there.
Thus, in accordance with the variation of the impedance of the
conductor line 9 from an extremely low value to a very higher one,
the heat generation in the short-circuited section of the pipe may
be controlled from almost no heat generation to the value attained
without such short circuiting.
FIG. 3 is a schematic representation in which a switchgear is
interposed at a position within the short circuit described above.
In this FIG., the short circuit, as set forth, is made by shunting
the section X-Y by at least one insulated conductor line 9 in the
inside of pipe 3, and the conductor line 9 is drawn out from said
pipe so as to connect with a switchgear 15 in series. When the
switch 15 is open, the shunting effect is eliminated; therefore,
heat is generated to the extent of full capacity. On the other
hand, when the switch 13 is closed, the heat generation will be
restrained in the shunted section from generating heat because a
greater amount of the current is shunted by the line 9. Thus,
actuation of the switch in on-off cycles can adjust the heat
generation. It goes without saying that the control of on-off
cycles may be done by an attached thermostat.
When the impedance is made much higher, the heat generation in the
section becomes almost the same with that of other sections of the
ferromagnetic pipe 3 where no short circuit is made.
The above-mentioned explanation has been given in case of the
control of heat generation in one section of a heat generating pipe
utilizing skin effect based upon such a circuit as in FIG. 2. In
cases of any number of plural section, it is also possible to
control heat generation in each section so as to make it take the
same or a different value in each of the sections.
Further, this invention can be also applied to a circuit other than
the above-mentioned ones, for example, such a circuit as described
in Japanese Pat. Application No. 20427/1966, entitled
"Heat-generating Pipe Utilizing Skin Effect Current," whose
counterparts are U.S. Ser. No. 627,086, Canadian Pat. Application
No. 986,431, West German Pat. Application No. P 1615192.1, British
Pat. Application No. 23142/68 and French PV 154842.
The above-mentioned Japanese patent application relates to a heat
generating pipe having an arrangement including a primary circuit
of an electric conductor line connected to a source of AC supply
and inserted within at least one pipe of ferromagnetic metal
throughout the entire length thereof in electrically insulated
relation from the inner wall portion of said pipe and a secondary
circuit consisting of said at least one pipe of ferromagnetic metal
and at least one conductor having an impedance as low as possible
and connecting the ends of said pipe, the secondary alternating
current induced in the secondary circuit by the primary current
being concentrated on the inner wall portion of said pipe on
account of the skin effect while satisfying the relations expressed
by equations (1) and (2).
The apparatus of the present invention can be applied with great
commercial advantage in various cases. For example it can be
applied to booster pumps, valves or the like installed in the
liquid transportation pipe described in Japanese Patent No.
460,224.
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