U.S. patent application number 12/136120 was filed with the patent office on 2008-12-25 for piping structure of heating/heat-retaining tube.
This patent application is currently assigned to NITTA MOORE COMPANY. Invention is credited to Kazunori SAWADA.
Application Number | 20080317450 12/136120 |
Document ID | / |
Family ID | 39735403 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080317450 |
Kind Code |
A1 |
SAWADA; Kazunori |
December 25, 2008 |
PIPING STRUCTURE OF HEATING/HEAT-RETAINING TUBE
Abstract
A piping structure of a tube for heating or heat-retaining of
fluid such as gas and liquid includes a conduit through which fluid
is transported and a plurality of heater lines inserted into the
conduit, in which the heater lines are connected in parallel. The
piping structure is capable of transporting fluid over a long
distance while heating the fluid or keeping the temperature of the
heated fluid constant even when the total piping length is
long.
Inventors: |
SAWADA; Kazunori; (Mie,
JP) |
Correspondence
Address: |
HAHN & VOIGHT PLLC
1012 14TH STREET, NW, SUITE 620
WASHINGTON
DC
20005
US
|
Assignee: |
NITTA MOORE COMPANY
Osaka
JP
|
Family ID: |
39735403 |
Appl. No.: |
12/136120 |
Filed: |
June 10, 2008 |
Current U.S.
Class: |
392/485 |
Current CPC
Class: |
F24H 1/102 20130101;
F16L 53/38 20180101; H05B 3/58 20130101; F01N 2610/02 20130101;
F01N 2610/14 20130101; F01N 3/2066 20130101; F16L 25/01 20130101;
F01N 2610/10 20130101 |
Class at
Publication: |
392/485 |
International
Class: |
F24H 1/10 20060101
F24H001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2007 |
JP |
2007-163413 |
Claims
1. A piping structure of a tube for heating or heat retaining of
fluid comprising: a conduit through which fluid is transported; and
a plurality of heater lines inserted into the conduit; wherein the
heater lines are connected in parallel.
2. The piping structure according to claim 1 further comprising at
least one tube joint; wherein a plurality of conduits are connected
with each other by the tube joint; and wherein lead wires for
transmitting power to the heater lines are connected to the heater
lines through the tube joint.
3. The piping structure according to claim 2, wherein the heater
line inserted into the conduit from one side are extended to the
tube joint connected to the conduit at the other side or extended
to the following conduit through the tube joint.
4. The piping structure according to claim 1, further comprising at
least one heater line having a different heat value.
5. The piping structure according to claim 2, further comprising at
least one heater line having a different heat value.
6. The piping structure according to claim 3, further comprising at
least one heater line having a different heat value.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a piping structure of a
tube for heating or heat-retaining of fluid such as gas and liquid
which flows in the tube.
[0003] 2. Description of the Related Art
[0004] As a conventional piping structure of a tube for heating or
heat-retaining of fluid flowing in the tube, such a piping
structure, for example, as shown in FIG. 7, has been known. The
piping structure includes a conduit 90 through which the fluid F is
transported, a heater line HL inserted into the conduit 90, and
lead wires LW which are electrically connected to the power supply
for transmitting power to the heater line HL at both ends of the
conduit 90, so that the fluid in the conduit 90 is heated to a
predetermined temperature while the fluid is transported from a
tank T1 positioned in a higher position to a tank T2 positioned in
a lower position (for example, Japanese Patent Application
Laid-Open (kokai) No. 2005-351333).
[0005] However, if a long tube or conduit is required to connect
the devices that are widely separated, a heater line which is
provided into the tube is also required to be made long in the
total length. Therefore, since the resistance value becomes higher
as the total length of the heater line gets longer, when the power
supply voltage is constant, the electric current value and, by
extension, the heating value are reduced, in turn leading to the
decrease in the efficiency of heating or heat-retaining of the gas
or liquid flowing in the tube. As a result, the conventional piping
structure of the tube has a difficulty in transporting fluid over a
long distance while heating the fluid or keeping the temperature of
the heated fluid constant.
SUMMARY OF THE INVENTION
[0006] Therefore, it is an object of the present invention to
provide a piping structure of a tube which is capable of
transporting fluid over a long distance while heating the fluid or
keeping the temperature of the heated fluid constant even when the
total piping length is long.
[0007] In order to achieve the above mentioned object, the piping
structure of a tube for heating or heat-retaining of fluid
according to the present invention includes a conduit through which
fluid such as gas or liquid is transported and a plurality of
heater lines inserted into the conduit, wherein the heater lines
are connected in parallel.
[0008] The piping structure of the tube for heating or
heat-retaining of fluid may further include at least one tube joint
wherein a plurality of conduits are connected with each other by
the tube joint, and wherein lead wires for transmitting power to
the heater lines are connected to the heater lines through the tube
joint.
[0009] Further, in the above described piping structure of the
tube, the heater line which is inserted into the conduit from one
side may be extended to the tube joint which is connected to the
conduit at the other side or may be extended to the following
conduit through the tube joint.
[0010] Furthermore, any of the above described piping structures of
the tube may include at least one heater line having a different
heat value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is an overall view of a piping structure of tubes for
heating or heat-retaining of fluid according to a first embodiment
of the present invention;
[0012] FIG. 2 is a partial cross sectional view of the tube for
heating or heat-retaining of fluid;
[0013] FIG. 3 is a cross sectional perspective view of a connecting
structure between the tubes;
[0014] FIG. 4 is an enlarged view of a connecting structure between
the heater line and the lead wire;
[0015] FIG. 5 is an overall view of a piping structure of tubes
according to another embodiment of the present invention;
[0016] FIG. 6 is an overall view of a piping structure of tubes
according to another embodiment of the present invention; and
[0017] FIG. 7 is an overall view of a piping structure of a
conventional tube.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Hereinafter, the present invention will be described in
accordance with drawings of embodiments thereof.
First Embodiment
[0019] As shown in FIG. 1, the piping structure according to the
present embodiment includes three tubes 1 between a device M1 and a
device M2 for heating up fluid to a predetermined temperature while
transporting the fluid from the device Ml to the other device M2,
three heater lines HL respectively inserted into the tubes 1 and
three lead wires LW respectively connected with the heater lines
HL. The heater lines HL are connected in parallel to a power supply
via lead wires LW. The heat value of the heater lines HL connected
in parallel is calculated by 3V.sup.2/R where the voltage of the
power supply is V, the resistance of the heater line HL is R, and
the voltage V is always constant, and this value is nine times
higher than the heat value of the heater lines HL in serial
connection which is calculated by V.sup.2/3R.
[0020] Such piping structure where a plurality of the heater lines
HL and tubes 1 are used to extend the entire length of the piping
structure and the heater lines HL are connected in parallel, makes
it possible to transport fluid over a long distance while keeping
the temperature of the fluid constant or heating the fluid with
maintaining the heat value even when the voltage of the power
supply is constant.
[0021] If a single long conduit is used, it is difficult for a
worker to install the conduit especially in a narrow space where
many devices or equipments are located. However, when a plurality
of conduits which are connected with each other by tube joints as
described above are used, it becomes easy to install or handle the
conduits even in the narrow space. Moreover, even in the case that
one of the heater lines in the conduits is required to be exchanged
due to the rupture or the like, the replacement work is easy since
the worker does not have to disconnect all the conduits but
disconnect only the corresponding conduit in which the ruptured
heater line is provided.
[0022] As shown in FIG. 1, the tube 1 is comprised of a conduit 10
and a heater line HL inserted into the conduit 10. The center tube
1 of the three tubes 1 is provided with tube joints 2 and 3 at both
ends of the conduit 10, and the right and left tubes 1, 1 are
provided with tube joints 4, 4 respectively at one end of the
conduits 10, 10. The tube joints 2 and 3 of the center tube 1 and
the tube joints 4, 4 of the right and left tubes 1, 1 are coupled
mutually to form one long passage for heating or heat-retaining of
fluid while transporting the fluid from the device M1 to the other
device M2.
[0023] The conduit 10 is designed to transport fluid such as gas or
liquid and is composed of resin (for example, fluorine resin) or
metal.
[0024] As shown in FIG. 2, one end of the heater line HL is
inserted into the conduit 10 from the tube joint 2 and extended to
near the connecting part between the tube joint 3 and the conduit
10 (inside of a bamboo shoot shaped joint section 20 of the tube
joint 3). At the connecting part, the heater line HL is folded back
to return into the tube joint 2 and is electrically connected to
the lead wire LW, which transmits power to the heater line HL.
[0025] As the heater line HL, a nichrome wire may be used, and the
heat value (wattage or watt density) of the heater line HL is set
to a predetermined value depending on operating conditions and the
voltage of the power supply, so that the heating or heat-retaining
capacity always falls within a permissible range. The heat value
can be set by adjusting the length of the tube 1 and the resistance
value of the heater line HL.
[0026] As an example of use, a plurality of the heater lines HL
whose heat value per meter is adjusted to, for example, 20 watts
per meter, are inserted into a plurality of tubes 1. In this case,
since the set heat value of 20 watts per meter is maintained
throughout the entire connected tubes 1, a long-distance
transportation of the fluid is possible without lowering the
temperature of the fluid. Since various types of heater lines HL
having different heat values can be combined freely; therefore, if
any conduit 10 has to be installed where the conduit is locally
heated by an external heat source, another heater line HL having a
lower heat value can be installed in the corresponding conduit to
control the temperature. For example, as shown in FIG. 5, in the
case where a urea aqueous solution is to be transported from a
liquid tank T to an exhaust air purifying system 70, it is assumed
that the surface temperature of a tube 1 between A and B near the
liquid tank T is -20.degree. C., and that a tube 1 between B and C,
which is installed in the vicinity of an exhaust tube 71 heated by
exhaust gas, is heated to a surface temperature of +20.degree. C.
by the radiation heat of the exhaust tube 71. In this case, into
the tube 1 between A and B, a heater line HL whose heat value is
relatively high may be inserted, so that the solution in the
environment of -20.degree. C. can be heated to a certain
temperature at which the solution is prevented from freezing, while
into the tube 1 between B and C, a heater line HL whose heat value
is relatively low may be inserted, so that the solution heated by
the radiation heat is prevented from boiling. As described above,
since the heat value of the heater line HL can be adjusted in
accordance with the thermal influence from outside, the product
lifecycle of the tube 1 can be extended, and the deterioration of
the fluid can be prevented.
[0027] The tube joint 2 is composed of resin (for example,
polyamide resin) or metal and, as shown in FIG. 3, includes a
bamboo shoot shaped joint section 20 to which a conduit 10 is
attached, a tube section 21 provided orthogonally to the axial
direction of the conduit 10, and a lead wire connecting section 22
where the lead wire LW connected to a power supply and a heater
line HL are connected mutually.
[0028] There are provided a plurality of circular protruding and
enlarged sections on the outer periphery of the bamboo shoot shaped
joint section 20. Therefore, the conduit 10 can be reliably
connected in a fluid-tight state by attaching an O-ring R or a seal
ring R onto the outer periphery of the bamboo shoot shaped joint
section 20.
[0029] As shown in FIG. 3, the tube section 21 is a female-type
circular member in which a circular diameter-enlarged section
(flange) F is integrally formed on an outer periphery thereof. A
male-type tube section 41 of a tube joint 4, which will be
described later, is inserted into the female-type tube section 21.
The flange F of the tube section 21 is confined by a retainer 6 in
this state, thereby connecting the tube joints 2 and 4 in a
retained state.
[0030] In order to facilitate heat transfer from the heater lines
HL in the both conduits 10 to the fluid, the length (L1) of the
tube sections 21 and 41 is set to be as short as possible, thereby
reducing the required heat capacity for the fluid. Moreover, in
order to improve the heat insulation property of the tube sections
21 and 41, a passage of the fluid is provided at the center of the
tube sections 21 and 41 which is far from the outside. The heat
insulation property is also maintained by the tube sections 21 and
41, and an air layer in a fitting gap (g) between the tube sections
21 and 41 formed by a rubber sealing 43 attached to the outer
peripheral wall of the tube section 41 (the tube sections 21 and
41, and the air layer forms a triple layer as a heat insulating
barrier). When above-described structure is employed, a plurality
of tubes 1 can be connected with each other without decreasing the
temperature of the fluid flowing in the tube sections 21 and 41 due
to the external air even in the case that no heater line HL is
provided in the tube sections 21 or 41, and stable heating or
heat-retaining performance can be maintained over a long distance,
and the entire heater system can be also simplified; therefore,
cost reduction can be expected.
[0031] The lead wire connecting section 22 is a section where the
lead wires LW connected to the power supply are led in and
connected to the heater line HL, and has a structure in which a
main body 61 is fit in a cylinder section 60 which constitutes a
part of the tube joint 2.
[0032] As shown in FIG. 4, the connecting structure between the
heater line HL and the lead wires LW in the lead wire connecting
section 22 includes: the cylindrical main body 61 housed in the
cylinder section 60 having a cylindrical inner peripheral surface
in a water-tight state; a through hole 62 extending in the main
body 61 in the circumferential axis direction; seal members 63
disposed in the regions on both sides of the through hole 62,
respectively; holes 64 formed coaxially with the through hole 62;
and retaining members 65 for retaining the seal members 63 in the
main body 61. A connecting section T of the heater line HL and the
lead wire LW is provided in the space of the through hole 62
between the seal members 63. The heater line HL penetrating through
one hole 64 and one seal member 63 is led into the connection
section T of the main body 61 from the conduit 10, while the lead
wire LW penetrating through the other hole 64 and the other seal
member 63 is led out from the connection section T to the power
supply side. By virtue of such a connecting structure between the
lead wire LW and the heater line HL, when many through holes (like
for example holes of a lotus root) are provided in one main body
61, the connecting structure between a lead wire LW and a heater
line HL per one line can be formed with a small space,
significantly simplifying wire connection and avoiding an
unfavorable twist of the lead wire LW and the heater line HL.
[0033] The main body 61, as shown in FIG. 4, has a cylindrical
shape, which is formed to have a slightly smaller diameter than the
inner diameter of the cylinder section 60, with an O-ring groove 66
provided on the outer peripheral surface thereof, wherein an O-ring
67 fits in the O-ring groove 66 to hold the main body 61 and the
cylinder section 60 in a fluid-tight state.
[0034] The through hole 62, as shown in FIG. 4, has a
small-diameter section 62a at the center thereof and large-diameter
sections 62b, which are larger than the small-diameter section 62a,
on both ends thereof.
[0035] The seal members 63 having a ring-like shape are fitted into
the large-diameter sections 62b in a tightly sealed state, so that
the lead wire LW and the heater line HL can be led into the
small-diameter section 62a in a tightly sealed state.
[0036] The tube joint 3 is composed of resin (for example,
polyamide resin) or metal like the tube joint 2, and connected to a
tube joint 4 of a tube 1 on the right side as shown in FIG. 1. The
basic structure thereof is the same as that of the tube joint 2
except that no lead wire connecting section 22 is provided. More
specifically, the tube joint 3 includes a bamboo shoot shaped joint
section 20 to which a conduit 10 is connected, and a tube section
21 provided orthogonally to the axial direction of the conduit
10.
[0037] The tube joint 4 is used in combination with the tube joint
2 or 3, is composed of resin (for example, polyamide resin) or
metal like the tube joint 2, and includes, as shown in FIG. 3, a
bamboo shoot shaped joint section 20 to which a conduit 10 is
attached, a tube section 41 provided orthogonally to the axial
direction of the conduit 10, and a lead wire connecting section 22
where lead wires 22 connected to a power supply and a heater line
HL are connected mutually. It is appreciated that, since the bamboo
shoot shaped joint section 20 and the lead wire connecting section
22 in the tube joint 4 basically have the same structure as those
in the tube joint 2, they are denoted by the same reference
numerals.
[0038] The tube section 41, as shown in FIG. 3, has a rubber
sealing groove 42 provided on the outer periphery thereof, wherein
a rubber sealing 43 fits in the rubber sealing groove 42 so that a
female-type tube section 21 of the tube joint 2 and a male-type
tube section 41 are connected with each other in a fluid-tight
state. The tube section 41 is provided with a pedestal 40 to
receive the retainer 6, which confines the flange F of the tube
section 21 so as to connect the tube joints 2 and 4 in a retained
state. The retainer 6 slides on the pedestal 40 in the direction
orthogonal to the tube section 41.
[0039] The piping structure of the tube according to this
embodiment has the following advantages.
[0040] Since the piping structure of a tube is configured as
described above, the present piping structure is capable of
transporting fluid over a long distance while heating the fluid or
keeping the temperature of the heated fluid constant even when the
total piping length is long. More specifically, since a plurality
of heater lines HL are connected in parallel, even when the voltage
from a power supply is constant and the total piping length is
long, the heat value per one heater line HL can be maintained
within a permissible range, thereby allowing long-distance
transportation of the fluid. Therefore, the connecting structure of
the tube 1 of the present invention has the same principle as that
of variable-length heaters, but causes no problem with the
variable-length heaters, such as high manufacturing cost, large
line diameter or weak mechanical characteristics, thereby improving
usability.
[0041] Since the outer periphery of the connecting area (tube
sections 21 and 41) of the tube joints 2 and 4 or of the connecting
area of the tube joints 3 and 4 does not have to be provided with
any additional heater device such as heater lines to maintain
stable heating or heat-retaining performance of the piping, there
is no need to prepare many kinds of heater lines HL having a
different resistance value selectively used depending on the total
length of the piping, and the work load of piping the tubes can be
significantly reduced, thus contributing to cost reduction.
[0042] Since the different heater lines HL having the different
wattage or watt density can be combined appropriately depending on
the situation or the client' needs, and the combination can be
easily changed, it becomes possible to find or provide the best
combination in a short period of time.
[0043] Since various types of heater lines having different heat
values can be combined to heat or retain the heat of the gas or
liquid that flows in the conduits, if one of the conduits has to be
installed where the outer surface of the conduit is locally heated
by an external heat source causing thermal damage to the fluid, a
heater line having a lower heat value can be installed in this
conduit in order to avoid the temperature of the fluid from being
too hot, and in turn reducing liquid deterioration. Therefore,
there is no need to install the conduit away from the heat source
to control the temperature.
Other Embodiments
[0044] In the above described first embodiment, the heater line HL,
as shown in FIG. 2, has a structure in which it is inserted into
the conduit 10 from the tube joint 2 side and bent to return into
the tube joint 2, in the vicinity of a connecting section between a
tube joint 3 and a conduit 10 (in a telescopic section 20 of the
tube joint 3); but the structure is not limited thereto. As shown
in FIG. 5, the heater line may be extended to the vicinity of a
tube section 21 of the tube joint 3 or even into the following tube
joint 4 or a conduit 10 connected thereto(on the right side in the
front view). Such a structure can further improve the performance
of heating or heat-retaining of the liquid in the tube joints 3 and
4.
[0045] The three tubes 1 shown in the above described first
embodiment may be connected via tube joints 5 as shown in FIG. 6 so
that the conduits 10 are arranged linearly. The tube joint 5 is a
T-shaped joint composed of resin (for example, polyamide resin) or
metal, and comprises bamboo shoot shaped joint sections 20 on both
sides thereof, to which the conduits 10 are attached, and a lead
wire connecting section 22 provided in the direction orthogonal to
the axial direction of the conduits 10. It is appreciated that,
since the bamboo shoot shaped joint sections 20 and the lead wire
connecting section 22 of the tube joint 5 basically have the same
structure as those in the tube joint 2, they are denoted by the
same reference numerals.
[0046] Further, the above described first embodiment employs a
combination of the three tubes 1 and heater lines HL having about
the same length, but the combination is not limited thereto. The
lengths of the tubes 1 or heater lines HL may be different.
Regarding the heater lines HL, those of which total length,
resistance values and heat values are adjusted as appropriate in
accordance with the purpose of use or the usage environment may be
used in combination.
[0047] Furthermore, in the above described first embodiment, one
heater line HL is inserted into each of the tubes 1, but the
configuration is not limited thereto. The devices M1 and M2 may be
connected by one long tube 1, and a plurality of heater lines HL
may be inserted thereinto and connected in parallel to a power
supply. In this case, holes for connecting lead wires LW which
transmit power to the heater lines HL are provided at predetermined
intervals in the tube 1. In addition, the holes are sealed with a
material such as nylon or fluorine resin to prevent leakage of gas
or liquid.
[0048] The above described first embodiment uses liquid as a
transported object, but gas can be also used.
[0049] Those skilled in the art will appreciate that various
adaptation and modifications of the just-described preferred
embodiment can be configured without departing from the scope and
sprit of the invention. Therefore, it is to be understood that,
within the scope of the appended claims, the invention may be
practiced other than as specifically described herein.
* * * * *