The present invention relates to an improved heating and melting
apparatus and, more particularly to a heating and melting apparatus for quickly
melting a substance to be melted such as snow, asphalt or the like and has particular
reference to an apparatus of the kind set forth in the preamble of claim 1. An
apparatus of this kind is known from US-A-3 405 705.
In areas subject to heavy snowfall, a great deal of human effort
as well as a large amount of money is required to remove snow from roads, railways,
air ports, cemeteries and the like.
Traffic conditions on roads and railways, however, remain badly degraded,
with the top speed and capacity of cars or trains severely limited, since the width
of the cleared surface of the road remains narrow due to snow drifts formed in
the snow removal process and due to the adverse effect on the road surface itself.
In recent years, the snow removal techniques have improved as have
apparatuses for removing snow. A known heating and melting apparatus such as the
apparatus of US-A-3 405 705 is provided with oil burners or gas burners for melting
a substance such as snow, asphalt or the like. There are however several difficulties
associated with the apparatus of US-A-3 405 705. E.g. the snow passed through the
screw conveyor has to be melted by a spray of hot water from the boiler. The boiler
has in turn to be supplied with water from the liquid receiving means. If this
liquid receiving means is empty before the apparatus is taken into use then there
is a danger that it will take a long time before sufficient hot water is available
to melt snow. If the liquid receiving means is first filled with warm water then
this is an added and unnecessary complication. If it is left full of water overnight
there is a danger it will freeze up altogether. Moreover, the use of a burner is
relatively inefficient since hot exhaust gases are bound to be wasted to some
degree. In addition the system proposed does not allow precise control of the energy
supplied and is wasteful of energy.
The apparatus of US-A-3 405 705 does however include a dispersion
unit making it possible to spray hot water over larger areas which can be of assistance
when wide areas are to be cleared, or when small pieces of ice are to be cleared
from roads, railways and the like. With other prior art apparatus it was impossible
to clear a really wide area to cope with snow drifting and to remove snow effectively.
It is an object of the present invention to provide a heating and
melting apparatus which corrects the abovementioned problems and can quickly melt
a substance to be melted and advantageously use the resulting melt.
To achieve the above object, the present invention provides an apparatus
of the initially named kind and having the characteristic features of claim 1.
It should be mentioned that the electrical and inductive heating of asphalt and
bitumen melting devices is known per se from US-A-4 028 527 and from Soviet Inventions
Illustrated, week J47, Abstract No. A 1810 Q 41.
Advantageous further developments of the invention are set forth
in the subordinate claims.
Features and advantages will be made apparent in the following description
with reference to the accompanying drawings:
In the drawings:
- Fig. 1
- is a block diagram of an embodiment of a heating and melting apparatus according
to the present invention;
Figure 2 is a flowchart of operation of the system of Figure 1;
Figure 3 is a plan view of a mobile heating and melting apparatus;
Figure 4 is a side view of the heating and melting apparatus of Figure
Figure 5 shows the other side of the heating and melting apparatus
of Figure 3;
Figure 6 is a partial plan view of a modification of a mobile heating
and melting apparatus;
Figure 7 is a side view of a modification of the heating and melting
apparatus of Figure 6;
Figure 8 is a block diagram of a modification to the heating and
melting apparatus of Figure 1;
Figure 9 is a cross-sectional view taken along line IX-IX of Figure
Figure 10 is a partial sectional view taken along line X-X of Figure
Figure 11 is a flowchart of operation of the heating and melting
apparatus of Figure 8; and
Figure 12 is a modified flowchart of operation of the heating and
melting apparatus of Figure 8.
Referring to the drawings, Figure 1 shows a heating and melting apparatus
of an embodiment according to the present invention. The heating and melting apparatus
comprises substantially a receiving member A for receiving a substance to be melted,
a transferring member B for conveying the substance to the receiving member A,
a heating member C for heating the receiving member A in order to melt the substance,
a heat energy supply member D for supplying heating energy to the heating member
C, a liquid receiving member E for receiving liquid from the receiving member
A, a liquid exhaust member F for exhausting the liquid stored in the liquid receiving
member E, and an operation control member G for controlling the heat energy supply
member D and the liquid exhaust member F.
The receiving member A includes a container (receptacle) 2 for receiving
a solid state substance such as snow from a snow removal vehicle (not show in Figure
1) through a lead pipe 1 and a melt housing in the form of a melting tube 3 of
which one end is secured to the container 2 so as to communicate with the container
2. The transferring member B includes a conveyor means in the form of a screw
conveyor 4, a drive motor 5 for driving the screw conveyor 4 and a variable speed
control device 6 for controlling the drive motor 5. The substance such as snow
is transferred from the snow removal vehicle by way of the lead pipe 1 to the
container 2. The snow stored in the container 2 is conveyed into the melting pipe
3 by means of the screw conveyor 4. The screw conveyor 4 is driven by the drive
motor 5 which is controlled by the variable speed device 6.
The heating member C comprises an inductive heating device IH including
a heating coil 7 wound around the melting tube 3 and a matching transformer 8.
The heat energy supplying member D includes an electric power control unit 9,
and a frequency converter 10 which controls the frequency of the electric power
to be supplied to the matching transformer 8 of the inductive heating unit IH.
A shield 11 surrounds the inductive heating unit.
An electric power supply in the form of an engine generator 21 is
electrically connected to the power control unit 9. The power control unit 9 is
connected to a frequency converter 10. The frequency converter 10 is electrically
connected to the induction heating coil 7 by way of the matching transformer 8.
The power control unit 9 controls the frequency converter 10, and thereby the
heating current of the inductive heating coil 7 is controlled to adjust the heat
applied to the melting tube 3. The melting tube 3 is made of a metallic material
such as magnetic material and is heated by the induction heating coil 7 to melt
the snow in the melting pipe 3.
The liquid receiving member E includes a vessel 12 for receiving
and storing the liquid from the melting tube 3 of the receiving member A. The vessel
12 is located to the free end of the melting tube 3. In the melting tube 3, the
snow is melted and the resulting water is further heated by the melting tube 3.
The hot water produced in the melting tube 3 is stored in the vessel 12.
The liquid exhaust member F comprises a drain 12a mounted near the
bottom of the vessel 12, a drain valve 12b mounted near the top of the vessel 12,
a dispersion unit 14 for dispersing the hot water in the vessel 12, and a return
line 19 for feeding some of the hot water in the vessel 12 back to the container
2. The dispersion unit 14 comprises a dispersing pump 15 equipped with a motor
16 and an ejection valve 17. The pump 15 is connected to one end of a pipe 18a,
the other end of which projects into the vessel 12. The return line 19 includes
a recirculating pump 20 driven by a motor 22 connected to a lead pipe 18b. One
end of the pipe 18b projects into the vessel 12, and other end of the pipe 18b
empties into the top of the container 2 by means of recirculating pump 20. A dust
filter 13 in the vessel 12 prevents particulates from the melting tube 3 from
entering the pipes 18a and 18b. The motors 5, 16 and 22 are electrically connected
to the engine generator 21 by way of switches 28 and 29, and a lead 30. Switches
31a and 31b are power source switches for motors (not shown in the drawings) driving
external devices (not shown in the drawings).
The operation control member G includes a thermosensor 23 mounted
on the melting tube 3 in order to detect the temperature of the melting tube 3,
a thermosensor 24 installed in the vessel 12 in order to detect the temperature
of the liquid stored in the vessel 12 and a thermal relay 23a for actuating the
switch 29 in response to the temperature of the driving motor 5. The operation
control member G further includes an input unit 25 receiving detection signals
from the thermosensors 23 and 24, a processing unit 26 in the form of a microprocessor
which receives signals from the input unit 25, and a setting and indication unit
27. The processing unit 26 uses the detection signals from the thermosensors 23
and 24 and the setting signals from the unit 27 to control the power control unit
9 and the switches 28, 29. The power control unit 9 controls the induction heating
member IH in response to instructive signals from the processing unit 26.
The operation of the heating and melting apparatus will be described
with reference to a flow chart shown in Figure 2.
An engine generator is started as shown at block B&sub1; and thus
an output voltage of the engine generator 21 rises to predetermined voltage as
shown at block B&sub2;. Thereafter, the apparatus is initialized at a block B&sub3;.
In block B&sub3;, various data are set to desired values via the setting unit
27. The various data include ice and snow conditions such as qualities of ice and
snow, ambient temperature, control gain, the temperature of the hot water and
the feed rate of the conveyor means. After initialization, the induction heating
unit IH is activated by means of an instruction from the processing unit 26, as
shown in a block B&sub4;. The electric power for the induction heating unit IH
is controlled by the power control unit 9, at a block B&sub5;. When the temperature
of the melting tube reaches or exceeds a predetermined value, the switch 29 is
closed in response to an instruction from the microprocessor 26, and thereby the
drive motor 5 is driven to operate the screw conveyor 4 as shown in blocks B&sub6;
If the temperature of the melting tube 3 is below the set value,
the control loop B&sub5;-B&sub6; for the electric power of the induction heating
unit is repeated.
When the screw conveyor 4 is running, the snow supplied by the removal
vehicle is conveyed to the container 2 as shown in blocks B&sub8;, B&sub9; and
B&sub7;. The snow stored to the container 2 is transferred to the melting tube
3 by means of the screw conveyor 4. The snow transferred into the tube 3 is melted
and thereby the hot water is produced since the melting tube 3 is already heated.
The hot water in the melting tube 3 is supplied to the vessel 12 for storage.
The temperature of the water in the vessel 12 is monitored by the thermosensor
24. If the temperature is less than the set value, the processing unit 26 proportionally
controls the heating current at a block B&sub1;&sub1; and the operations shown
in the blocks B&sub5;, B&sub6;, B&sub7; and B&sub1;&sub0; are repeated until the
temperature of the water reaches the set value. After the temperature of the water
reaches the set value, the switch 28 is closed in response to an instruction from
the processing unit 26, which also orders operation of the motors 16 of the dispersion
pump 15 and the motor 22 of the recirculation pump 20.
The recirculating pump 20 returns hot water from the vessel 12 to
the container 2 in order to facilitate melting of the snow in the receiving member
A, as is shown in a block B&sub1;&sub2;a. When the water level reaches a predetermined
level, the dispersion unit 14 is activated to spray a high pressure hot water jet
over snow on roofs, roads or the like at blocks B12b, B13b
and B14b, and thereby fulfilling the desired purpose of the apparatus.
When the vessel 12 is full, water drains through the overflow pipe 12b, as shown
in blocks B12c and B13c.
The heating and melting apparatus shown in Figure 1 can be mounted
on a vehicle such as a truck trailer as is shown in Figures 3 to 5. In Figures
3 to 5, elements identical or corresponding to those shown in Fig. 1 are labelled
with the same reference characters. As shown in Figures 3 and 4, the container
2 is mounted on the rear end of a truck trailer 32 (the left-hand side in Figures
3 and 4), and the vessel 12 is mounted on the front end of the truck trailer 32
(the right-hand side in Figures 3 and 4). The electrical generator 21 and the inductive
heating unit IH are mounted on the trailer truck between the container 2 and the
vessel 12. The container 2 is connected to the vessel 12 by way of a melting tube
3 as shown in the rear view of Fig. 5.
The apparatus of Figure 1 can also be used in conjunction with a
paving apparatus for paving roads with asphalt. Figures 6 and 7 show a paving apparatus.
A paving machine 60 is mounted on a truck trailer 32 in place of the vessel 12
(shown in Figure 1) after removing the vessel 12. The paving machine 60 is provided
with the stirring device 61, an extruder 62 and a pressing plate 63.
Although Figures 3 to 7 show mobile heating and melting apparatus,
the invention is not limited to this type, but rather may be stationarily mounted.
By mounting the engine generator 21 on another vehicle, a part of the apparatus
is made small and thereby operation can be carried out in the narrower area.
Figures 8 to 10 show a modification to the heating and melting apparatus
of Figure 1. According to the apparatus of Figures 8 to 10, a hot blast blows
continuously through a receiving member receiving a substance to be melted, and
thereby the receiving member is heated in order to melt the substance conveyed
into the receiving member. The resulting liquid can be employed to melt snow and
its melting efficiency can be enhanced by recirculating the heated liquid through
the receiving member.
As is shown in Figure 8, a receiving member A receiving a substance
to be melted includes a melting tube 3A. A heating member C comprises a plurality
of heat pipes 32 and associated electric heaters 33 mounted on the heat pipes
A heating energy supply unit D includes an electric power control
unit 9 and compressors 34 connected electrically to the control unit 9. Each of
the compressors 34 is connected to a corresponding heat pipe 32 by way of a corresponding
air conduit 36. The electric heaters 33 are electrically connected to the power
control unit 9 by power lines 37. The melting tube 3A is connected to a gasoline
or diesel generator 21 via a conduit 38 and an inlet port 39. The exhaust gas from
the engine generator 21 is conducted to the melting tube 3A by way of the conduit
38 and the inlet pipe 39. The exhaust gas passes through the melting tube 3A and
exit via an outlet pipe 40.
As is best shown in Figures 9 and 10, the melting tube 3A is formed
with a first tubular section 41a, a second tubular section 41b having a smaller
diameter than the first tubular section, a third tubular section 41c having a
diameter smaller than the second tubular section, and a disc-shaped plate 42 with
a central bore 42a fastened to the upstream end of the melting tube 3A. An adiabatic
material 43 is inserted between the first tubular section 41a and the second tubular
section 41b. A cavity 44 is defined between the second and third tubular sections.
A heating medium, specifically exhaust gases from the engine generator, is supplied
to the cavity 44 (as described above).
As shown in Figure 9, hot jets enter the melting tube 3A through
the heat pipes 32 to heat the melting tube 3A and to melt the snow directly. The
plurality of heat pipes 32 surround the melting tube 3A in a plurality of heating
element groups 32A. As shown in Figure 9, the heating element groups 32A are spaced
along the length of the tube 3A and form the heating member C. The heat pipes
32 of each heating element group 32A are connected to corresponding air conduits
36 by way of a common air conduit 46 and individual branch pipes 47. The air conduits
36, the common air conduit 46 and the branch pipes 47 are insulated with the adiabatic
material according to need.
As shown in Figure 10, each heat pipe 32 is secured by a support
48 disposed between the second and third tubular sections of the melting tube 3A.
Adiabatic material 55 fills the gaps between the heat pipe 32 and
the support 48. The stainless steel inlet pipe 39 connects the engine generator
21 to the gap 44 between the first and second tubular sections. Each of the heaters
33 is wound around the corresponding heat pipe 32. These heaters 33 are connected
to the control unit 9 by leads 37. The use of the heat pipe 32 makes the heating
member C of the heating and melting apparatus small size and light weight as well
as optimum heat control can be performed ecconomically.
As described above, the melting tube 3A is heated by the hot gases
from the heat pipe 32 and the engine generator 21. The heat pipes 32 are heated
or preheated by the electric heaters 33 and thereby the heating efficiency of
the heating member C is considerably enhanced.
The operation of the apparatus of Figures 8 to 10 will be explained
with reference to Figure 11. The power control unit 9 is activated in response
to an instruction from the microprocessor 26 after the output voltage of the engine
generator 21 is established. Upon activation of the power control unit 9, operation
of the compressors commences as shown in a block B15, and compressed
air is supplied to the heat pipes 32. The hot jets blow into the melting tube
3A, as is shown by the arrows in Figure 10. Activation of the power control unit
9 also initiates current supply to the heaters 33 as shown in blocks B16
and B17. The exhaust gas from the engine generator 2l is supplied to
the melting tube 3A whereby the exhaust gas is employed to heat the melting tube
3A, as is shown in a block B18.
If the temperature of the melting tube 3A is equal or lower than
a set temperature, the heat pipes 32 are continuously heated by adjusting their
supply voltage. Moreover, the number of the heat pipes 32 and heaters 33 used
is selected in accordance with the temperature of the liquid stored in the vessel
12 and the melting tube 3A. Specifically, the processing unit 26 uses the detection
signals from the thermosensors 23 and 24 to control the power control unit 9.
The power control unit 9 controls the power of the compressors 34 and the electric
heater 33 so as to control the temperature of the melting tube 3A.
According to the apparatus of Figures 8 to 10, an inductive heating
unit can be added to the heat energy supply unit D if the heating rate due to the
hot air jets from the heat pipes 32 must be augmented. An inductive heating unit
70 is provided in each of the conduits 36 as is shown in Figure 8. Electrical power
is supplied to the inductive heating units 70 via a frequency converter 10.
In the heating and melting apparatus having the inductive heating
units 70, the inductive heating units 70 are operated after the air compressor
34 are started as shown in blocks B15 and B19 of Figure 12.
When the inductive heating units 70 are running, the power control unit 9 controls
the frequency converter 10 and thereby controls the inductive heating units 70
as shown in a block B20. After controlling the inductive heating unit
70, the electric power is supplied to the electric heaters 33 as shown in a blocks
B16 and thereafter the heater voltage is adjusted (block B17).
After adjustment of the heater voltage, power control for the inductive heating
units 70 and adjustment of the heater voltage is repeated as long as the temperature
of the melting tube 3A remains lower than the set value.
The heating and melting apparatus of Figure 8 can be made more compact
and lighter as well as being provided enhanced temperature characteristics due
to the heat pipes 32 in the heating member C. Moreover, the heating and melting
apparatus of Figure 8 can control suitably heat of the melting tube 3A heat control,
since the number of using heating elements 33 can be selected according to need.
According to the present invention, a receiving member for receiving
a substance to be melted is continuously heated without the need for a naked flame.
Accordingly, a heating and melting apparatus of the invention is safe to use.
According to the present invention, the liquid obtained by melting
the substance to be melted can be used effectively. Accordingly, the heating and
melting apparatus of the invention is very well adapted for removing snow from
roads, railways and the like.
In cases where the heating and melting apparatus of the invention
is employed for snow removal, various advantageous effects can be obtained. One
of these advantages is that the apparatus of the invention can be used in a narrow
area such as in a rail-way station, a residential area, a cemetary, etc., since
the snow can be removed without spreading the snow.
By employing the heating and melting apparatus of the present invention
to a snow removing apparatus, following advantageous effects are obtained:
Operation can be performed smoothly, since snow is melted by the
heating and melting apparatus without transferring the snow to another place.
Performance of snow removing is further enhanced since hot water
is dispersed after melting the snow.
Reduction of working hours for snow removing can be carried out by
means of melting the snow.
The number of operator for snow removing can be reduced since the
apparatus is automatically operated.
Another advantage is that the number of operators can be reduced
since the apparatus can be operated automatically.
In view of the above, it will be seen that the various objects of
the invention have been fulfilled and many advantageous results are achieved.