Combustion apparatus and method of forcibly circulating a heating medium in a combustion apparatus

In a combustion apparatus, gas for combustion is fed in a combustion chamber receiving a heating medium such as sand to continuously blow the heating medium upwardly to thereby circulate the heating medium in the combustion chamber.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention relates to a combustion apparatus and a method of 
forcibly circulating a heating medium in a combustion apparatus. 
There have been known methods of combustion and combustion apparatuses in 
which a heating medium such as sand, gravel contained in a combustion 
chamber is mixed with fuel and the fuel is fired. 
According to the invention, a combustion apparatus includes a combustion 
chamber, a particulate heating medium in the combustion chamber and 
conduit means having a nozzle for feeding upwardly into the combustion 
chamber a combustion gas, whereby the heating medium is circulated in the 
combustion chamber. An intake port communicates a lower portion of the 
combustion chamber with a portion of the conduit means upstream of the 
nozzle. The intake port extends into a bottom of the combustion chamber. 
Pressure reducing means are associated with a junction of the intake port 
and the conduit means and induce the heating medium to flow into the 
intake port. In one embodiment, the pressure reducing means is in the form 
of a reduction in the sectional area of the conduit means adjacent to the 
junction. In another embodiment, the pressure reducing means is in the 
form of a nozzle. 
A fuel supplying pipe has an end introduced into the intake port for 
inducing the heating medium to flow into the intake port at a rate 
proportional to that of the fuel. The fuel supplying pipe preferably 
extends downward toward the end thereof in a vertically extending portion 
of the intake port. Separate means may be provided for supplying fuel to 
the combustion chamber and a separate burner for heating the combustion 
chamber may be provided. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method and an 
apparatus capable of burning cinders and so on produced from lower 
calorific oil fuel in which before introducing material to be burned into 
a combustion chamber, a heating medium for continuously heating the 
material to be burned at such a temperature that the material fires 
itself, is forcibly circulated by using gas for combustion. 
An aspect of the present invention is to provide a method of forcibly 
circulating a heating medium in a combustion apparatus by feeding gas for 
combustion in a combustion chamber receiving a heating medium to 
continuously blow the heating medium upwardly to thereby circulate the 
same in the combustion chamber. 
Another aspect of the present invention is to provide a combustion 
apparatus provided with a combustion chamber containing a heating medium 
including means for feeding gas for combustion into the combustion chamber 
to blow the heating medium upwardly to thereby circulate the heating 
medium in the combustion chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The first embodiment for a forced circulation method and an apparatus for 
carrying out the method of the present invention will be described with 
reference to FIG. 1. 
A combustion chamber 110 in which forced circulation of a heating medium is 
affected is defined by a side circumferential wall 111 and a bottom wall 
112. The upper part of the combustion chamber may be covered by a suitable 
cover provided with an exhaust pipe. Alternatively, it is possible to 
connect the upper part of the combustion chamber to the corresponding part 
of another equipment so that heat energy produced in the combustion 
chamber is transmitted to the equipment which requires heat energy. A 
reference numeral 200 designates a heating medium such as sand, gravel, 
ceramic particles received in the combustion chamber 110 to burn solid 
fuel in a powdery or a particulate form, or liquid fuel. A numeral 331 
designates a fuel supplying pipe for supplying the solid fuel or the 
liquid fuel into the combustion chamber, the fuel supplying pipe being 
generally provided at a proper position between an intake port 551 and a 
nozzle 552, both being described later and a numeral 400 generally 
designates a pilot burner means for heating the heating medium 200. 
A conduit 500 which constitutes a part of a feeding means for feeding gas 
for combustion such as air is provided in the combustion chamber 110 so as 
to direct the nozzle 552 formed at an end of the conduit upwardly. The 
intake port 551 is formed in the bottom wall 112.to connect the combustion 
chamber with the conduit 500 extending laterally below the bottom wall 
112, at a junction therebetween. However, it is possible that the conduit 
500 is introduced in the combustion chamber through the side 
circumferential wall 111 of the combustion chamber and the intake port is 
formed at a part of the conduit extending laterally in the combustion 
chamber so that the opening of the intake port is directed upwardly. 
In the combustion chamber having the construction as above-mentioned, when 
gas for combustion such as air is forcibly fed through the conduit 500, a 
part of the heating medium is sucked through the intake port 551 and is 
discharged from the nozzle 552 together with air. In this case, fuel such 
as A-type heavy oil, kerosine is fired by electric discharge in the pilot 
burner 440. The heating medium discharged from the nozzle 552 of the 
conduit is heated by flames 441 from the pilot burner or a hot gas 
produced by the pilot burner. Air is supplied through the pilot burner 
means 400 into the combustion chamber to spread the pilot flames and the 
hot gas in the combustion chamber. Depending on a sort of fuel, fuel may 
be supplied from the fuel supplying pipe after firing of the pilot burner 
to ignite the fuel thereby heating the heating medium. 
The heating medium 200 heated by the pilot flames or the hot gas gradually 
falls and is finally sucked into the intake port 551 to be discharged in 
the combustion chamber 110 through the nozzle 552. By repeating the 
above-mentioned process, the heating medium reaches a predetermined high 
temperature. At the moment, liquid or solid fuel is put into the 
combustion chamber through the fuel supplying pipe 331. The fuel is 
introduced in the conduit from the intake port 551 together with the 
heating medium heated at a high temperature to be discharged into the 
combustion chamber through the nozzle 552. By repeating the process the 
fuel is mixed with the heating medium at a high temperature to be heated 
thereby causing evaporation. Then, the fuel is fired by the pilot flames 
441 or by natural ignition by the aid of the hot gas and the heating 
medium heated at a high temperature. Upon ignition of the fuel, the 
operation of the pilot burner is stopped. 
Even after the operation of the pilot burner is stopped, the fuel is 
continuously supplied through the fuel supplying pipe 331 so that it is 
circulated through the conduit 500 along with the heating medium of a 
highly elevated temperature. As long as the fuel is fired even after the 
stoppage of the pilot burner, the heating medium accelerates evaporation 
of the fuel during the circulation of the heating medium and maintains 
combustion at good condition. 
When air is supplied to the combustion chamber through the conduit, the 
heating medium 200 near the intake port 551 is introduced in the conduit 
due to the dead weight. Further, introduction of the heating medium into 
the conduit can be effectively and certainly carried out by rendering an 
inner pressure of the conduit 500 at the intake port 511 to be lower than 
a pressure in the combustion chamber. 
Obstacle plates 600, 660 may be provided at suitable positions at the upper 
part of the combustion chamber. With the obstacle plates 600, 660, the 
heating medium 200 discharged upwardly from the nozzle 552 impinges on 
them and falls due to gravity and then is returned to the intake port 551 
for circulation. 
It is preferable that the opening of the fuel supplying pipe 331 faces the 
intake port 551 because the fuel and the heating medium fall in the 
conduit at an adequate proportion and are uniformly mixed while they are 
passed through the conduit together with the gas for combustion. 
In the combustion apparatus as shown in FIG. 1, an amount of the heating 
medium 200 subjected to circulation can be controlled as desired by 
changing the size of the intake port 551 and a flow rate of air. 
FIG. 2 shows the second embodiment of a forced circulation method and an 
apparatus for carrying out the method according to the present invention. 
In the second embodiment, a reduced aperture nozzle 553 is provided at the 
intake port 551 in the conduit 500. The nozzle renders a pressure in the 
conduit at the intake port to be lower than a pressure in the combustion 
chamber 110, whereby the resulting pressure difference effectively sucks 
the heating medium in the conduit. It is possible to place a partition 
plate, an inclined plate and so on to narrow the passage of the conduit, 
instead of the nozzle 553. Further, the intake port may be formed in the 
side wall of the conduit extending vertically in the combustion chamber 
instead of the intake port formed in the bottom wall of the combustion 
chamber. In this case, the same effect can be obtained. 
The third embodiment of a forced circulation method and an apparatus for 
carrying out the method of the present invention will be described with 
reference to FIG. 3. In FIG. 3, the same reference numerals as in FIGS. 1 
and 2 designate the same or corresponding parts and therefore, description 
of these parts is omitted. The nozzle 552 extends in the combustion 
chamber 110 downwardly so that the opening of the nozzle faces the bottom 
wall 112 of the combustion chamber 110 with a suitable gap. The nozzle is 
connected to the conduit 500 which extends into the combustion chamber by 
passing through the side circumferential wall 111 from the outside so that 
air 532 is fed through the conduit. 
Near the lower central portion of the combustion chamber, a flow-regulating 
means 140 provided with an opened top, a side circumferential wall and a 
bottom wall is provided. The a suitable gap is formed between the 
flow-regulating means 140 and the nozzle 553 so that discharged air is 
directed upwardly. The flow-regulating means may be in a cylindrical form 
or another form instead of the inversed frustum shape as shown in FIG. 3. 
In the Figure, the flow-regulating means is so formed as to be part of the 
bottom wall of the combustion chamber. However, it is possible to 
construct a flow-regulating means separately and place it on the bottom 
wall. Thus, by providing the flow-regulating means at the lower part of 
the combustion chamber and by directing the opening of the nozzle into the 
flow-regulating means, the air discharged from the nozzle is effectively 
directed upwardly to increase the function of blowing-up of the heating 
medium. 
Blades may be attached to the nozzle 552 on the inner side wall of the 
flow-regulating means 140 so that air goes upwards under swirling 
movement. 
The fuel supplying pipe 331 is placed in the combustion chamber at a 
position away from the bottom wall to feed solid fuel in a powdery or a 
particulate form or liquid fuel. The top end portion of the pipe 331 is 
preferably in an annular shape surrounding the nozzle 552. A plurality of 
apertures are formed in the end portion of the pipe so that fuel is 
supplied through the apertures. 
A plurality of discharge openings 670 for secondary air for combustion is 
formed in the side wall of the combustion chamber near an opening 462 for 
directing a pilot flames 441 to the combustion chamber, at an angle 
between the radial direction and the tangential direction to the center of 
the combustion chamber. An angle of elevation of the discharge openings is 
determined so as to produce an swirling air stream in the combustion 
chamber. 
In the third embodiment, the same function of forcibly circulating the 
heating medium as the first and second embodiments can be obtained even 
though the direction of discharging of air is different from the first and 
second embodiments. Namely, the air ejected from the nozzle 552 hits the 
bottom wall of the combustion chamber or the flow-regulating means and is 
strongly raised upwardly, whereby the heating medium 200 is blasted 
upwardly. 
In a case that discharge openings 670 for the secondary combustion air is 
formed in the side wall 111 of the combustion chamber, when supply of the 
air from the nozzle 552 is short for an amount of fuel supplied, air can 
be supplied from the discharge openings 670 to attain good combustion. 
Heat produced in the combustion apparatus of the present invention can be 
finely and quickly controlled by adjusting supply of the fuel 351 to be 
fed into the combustion chamber through the fuel supplying pipe 331, or by 
adjusting an amount of air discharged from the nozzle 552 for blasting the 
heating medium, or by adjusting an amount of the secondary combustion air 
in case that the discharge openings 670 a provided. 
FIG. 4 shows the fourth embodiment of a forced circulation method and an 
apparatus for carrying out the method according to the present invention. 
The fourth embodiment is substantially the same as the third embodiment 
except that a ringed body 780 having a side circumferential wall and 
openings at the top and the bottom is placed above the nozzle 552 and with 
a gap between the lower edge of the ringed body and the bottom wall of the 
combustion chamber. The shape of the ringed body 780 can be a desired form 
such as a cylindrical form, an inversed frustum shape. In FIG. 4, the 
upper part of the ringed body is surrounded by the annular part of the 
fuel supplying pipe 331. However, a positional relationship between them 
can be determined as desired. 
In the operation of the combustion apparatus according to the fourth 
embodiment, since the heating medium 200 is blasted upwardly through the 
ring body 780, the heating media 200, 220 flow in the gap between the 
lower edge of the ringed body 780 and the bottom wall of the combustion 
chamber (or the upper end of the flow-regulating means 140). Namely, the 
blasted heating medium 220 is moved from the outside of the ringed body to 
the gap and is passed through the inside of the ringed body to be 
circulated. Accordingly, an amount of the heating medium to be circulated 
increases, hence the heat quantity of the heating medium increases whereby 
evaporation of the fuel is accelerated. In this case, further excellent 
combustion can be maintained even through unflammable material such as 
water is mixed in the fuel. 
FIG. 5 shows the fifth embodiment of the combustion apparatus according to 
the present invention. In the fifth embodiment, the nozzle 552 extends 
laterally in the combustion chamber to blast the heating medium upwardly, 
this constituting substantial difference from the first to the fourth 
embodiments. Further, the fifth embodiment is provided with a funnel-like 
slanting surface 130 attached to the lower part of the combustion chamber. 
The slanting surface 130 provides further effective circulation of the 
heating medium. The slanting surface 130 can also be provided in the first 
to fourth embodiments to attain the above-mentioned function. 
FIG. 6 shows the sixth embodiment of the combustion apparatus according to 
the present invention. The fundamental feature of the sixth embodiment is 
that the pilot burner means 400 including the pilot burner 460 and the 
opening 462 for guiding the pilot frame 441 or the hot gas in the 
combustion chamber is provided at the bottom of the combustion chamber. 
Further, the slanting surface 130 and the ringed body 780 may be placed as 
in the fifth embodiment. 
The operation of the sixth embodiment will be described. When the heating 
medium 200 is blown upwardly by the air for combustion ejected from the 
nozzle 552, the hot gas from the opening 462 is also directed upwardly 
together with the air, whereby the heating medium is heated from the lower 
part. 
The seventh embodiment of a forced circulation method and a apparatus for 
carrying out the method according to the present invention will be 
described. 
In FIG. 7, an annular diffuser 830 with its top and bottom opened is placed 
at the lower central portion in the combustion chamber and at a position 
away from the side wall and the bottom wall 112 of the combustion chamber. 
The diffuser may have a desired shape such as a cylindrical shape although 
it has an inversed frustrum shape in the FIG. 7. It is preferable that the 
upper end of the diffuser is located above the upper surface of the 
accummulated heating medium 200. The diffuser may be attached to the 
combustion chamber by means of legs connected to the bottom wall and 
radial arms connected to the side wall of the combustion chamber. 
The pilot burner means for heating the heating medium at an initial stage, 
indicated by a numeral 400 as a whole, is provided with the nozzle 552 
which extends passing through the bottom wall 112 of the combustion 
chamber and has an opening. The opening faces the lower opening of the 
diffuser 800 with a suitable gap. The outer diameter of the opening is 
smaller than the inner diameter of the lower opening of the diffuser 830. 
Preferably, the shape of both the openings is circular and the axial lines 
of the both openings are aligned. A fuel spraying nozzle 443 is provided 
in the burning room 411 of the burner means 400 and the spraying nozzle 
443 is communicated with a fuel tank 444 holding oil such as an A-type 
heavy oil, kerosine through a fuel supplying pump 445, a suitable valve 
means 446 and a pipe. An ignition plug 448 of an ignition device 447 is 
provided in the front of the spraying nozzle 443 in the burning room 411 
to fire the fuel from the spraying nozzle 443. A pipe 511 for feeding air 
from a blower 550 is connected to the burning room 411 of the burner means 
400. In this embodiment, the pipe 511 is connected to the burning room in 
the rear of the open end of the spraying nozzle, namely, on the right hand 
of the spraying nozzle in FIG. 7. 
Condition for the operation of the combustion apparatus is so determined 
that an amount of air discharged from the blower is sufficient for 
combustion in the combustion chamber and the burning room; pressure around 
the nozzle 552 is lower than that of the upper part of the combustion 
chamber when the air is blasted from the open end of the nozzle 552 
towards the combustion chamber; and the heating medium in the vicinity of 
the nozzle is blown upwardly, to thereby providing a cavity, whereby the 
heating medium is collected in the vicinity of the nozzle. 
A numeral 360 designates a tank in which fuel including inflammable powdery 
and particulate material, inflammable fluid such as slush containing solid 
material having a high ignition temperature and uninflammable fluid such 
as water is received. The tank is connected to the combustion chamber 
through a supplying means 300 inclusive of a pump 361 and a valve means 
362 to supply the fuel on the heating medium 200. The supplying means 300 
comprises a pipe 371 wound around the outer circumferential wall of the 
combustion apparatus 100 in a helical form and a circle portion 
surrounding the upper part of the diffuser 830 placed in the combustion 
chamber. A plurality of apertures are formed in the circle portion to 
eject the fuel on the heating medium 200. 
The operation and function of the combustion apparatus of the seventh 
embodiment will be described. 
A hot gas discharged from the nozzle 552 is passed through the diffuser 830 
facing the nozzle 552. In this case, pressure in the vicinity of the lower 
opening of the diffuser 830 becomes higher than pressure at the outlet of 
the nozzle 552 thereby resulting a pressure difference. Accordingly, the 
heating medium 200 is sucked in the diffuser 830 together with water and 
oil vaporized by heat of the heating 200 medium, due to the pressure 
difference. While the hot gas and heating medium are passed through the 
diffuser 830, the heating medium 200 is heated by the hot gas (FIG. 8). 
The heating medium 200 discharged from the upper opening of the diffuser 
830 is accumulated on the heating medium outside the diffuser (as 
indicated by broken arrow marks in FIG. 8). Since the heating medium is 
sucked sequentially into the diffuser from its lower part, the heating 
medium is gradually heated by the hot gas during movement of circulation. 
The fuel is supplied on the heating medium 200 through the apertures 
formed in the circle portion 372 wound around the upper part of the 
diffuser. The fuel is mixed with the heating medium 200 and falls between 
the outer wall of the diffuser 830 and the inner wall of the combustion 
chamber together with the heating medium. In this case, water content in 
the fuel is vaporized by heat from the heating medium and the oil content 
in the fuel is gasified to be burned in the combustion chamber. The solid 
content in the fuel which has not been completely burned is subjected to 
movement of circulation together with the heating medium 200 and is 
repeatedly passed through the diffuser for burning. 
In the first to the seventh embodiments, an exhaust pipe may be provided at 
the upper part of the combustion chamber. In this case, the position of 
the exhaust pipe is deflected laterally from the position of the nozzle at 
a suitable distance, whereby scattering of the heating medium can be 
prevented. 
In accordance with the method and the apparatus for carrying out the method 
according to the present invention, solid or liquid fuel and a heating 
medium are heated and circulated in a combustion chamber by the action of 
air discharged from the blowing-up means. Accordingly, sufficient 
combustion can be obtained even though fuel containing uninflammable 
components e.g. heavy oil or lubricating oil containing about 70% of water 
is used. Further, adjustment of heat quantity produced in the combustion 
chamber is easy, whereby flexible operation can be attained for variation 
of a load. Accordingly, effective combustion can be obtained even when a 
load is small. 
The combustion apparatus of the present invention is applicable not only to 
a heat source for a room warming apparatus or a water supplying apparatus 
which require heat energy but also to an incinerator. The combustion 
apparatus of the present invention is applicable to various fields.