CA2013302C - Method and apparatus for burning liquid fuel - Google Patents
Method and apparatus for burning liquid fuelInfo
- Publication number
- CA2013302C CA2013302C CA 2013302 CA2013302A CA2013302C CA 2013302 C CA2013302 C CA 2013302C CA 2013302 CA2013302 CA 2013302 CA 2013302 A CA2013302 A CA 2013302A CA 2013302 C CA2013302 C CA 2013302C
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- air
- combustion
- combustion chamber
- liquid fuel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 128
- 239000007788 liquid Substances 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000002485 combustion reaction Methods 0.000 claims abstract description 119
- 239000006260 foam Substances 0.000 claims description 47
- 238000005187 foaming Methods 0.000 claims description 20
- 238000001704 evaporation Methods 0.000 claims description 10
- 239000003381 stabilizer Substances 0.000 claims description 6
- 239000002245 particle Substances 0.000 abstract description 4
- 239000004744 fabric Substances 0.000 abstract description 3
- 239000003921 oil Substances 0.000 description 21
- 230000001105 regulatory effect Effects 0.000 description 21
- 230000001965 increasing effect Effects 0.000 description 19
- 230000003247 decreasing effect Effects 0.000 description 14
- 239000007789 gas Substances 0.000 description 13
- 230000001276 controlling effect Effects 0.000 description 11
- 239000002828 fuel tank Substances 0.000 description 9
- 230000035943 smell Effects 0.000 description 8
- 238000009834 vaporization Methods 0.000 description 8
- 230000008016 vaporization Effects 0.000 description 8
- 239000007921 spray Substances 0.000 description 7
- 239000003350 kerosene Substances 0.000 description 6
- 230000005587 bubbling Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003028 elevating effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000004088 foaming agent Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000002085 irritant Substances 0.000 description 1
- 231100000021 irritant Toxicity 0.000 description 1
- 229910001120 nichrome Inorganic materials 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Landscapes
- Evaporation-Type Combustion Burners (AREA)
- Spray-Type Burners (AREA)
Abstract
A method and apparatus for burning a liquid fuel by introducing gas into the liquid fuel through capillaries, a porous plate, cloth, a particle layer or the like to bubble the liquid fuel to control the fuel level and simultaneously by supplying combustion air separately to accomplish complete combustion.
Description
2 ~
TITLE OF THE INVENTION
Method and apparatus for burning liquid fuel BACKGROUND OF THE INVENTION
1. Field of the invention The present invention relates to a method and apparatus for burning liquid fuel in a wide range of applications from household oil stoves up to industrial furnaces.
2. Description of the prior art A heretofore known practice is to burn liquid fuel either directly gasified or as finely vaporized by an atomizer.
The former method of burning the directly gasified fuel is widely used in general household oil stoves, typical of which are a pot type (JU-A-No.
35713/1983), a wick type (JP-A-Nos. 203307/1983 and 64134/1985) and a vaporization type (JIS 3030).
The pot type employs a burner bowl on which fuel is vaporized before being burned and is equipped with a combination of vaporization and combustion units.
In the case of the vaporization type, fuel is vaporized in a vaporization chamber or pipe and then burned in a combustion unit, the vaporization unit being separated from the combustion unit.
Although the method of burning gasified fuel is used in some household oil stoves, it is more generally used in industrial furnaces, boilers and the like. This 201330~
_ - 2 burning method is designed to promote vaporization and combustion reaction by gasifying liquid fuel into fine oil drops to increase the contact area of each drop with air.
Oil burners generally in use are adapted to burn fuel by means of a rotary burner, jet burner (vaporization spray, air spray and mechanical spray), special burner (gun-type high-pressure spray and low pressure spray) or the like. There are also examples having a kind of ignition device for igniting liquid fuel in the form of foam (JP-B-No. 42018/1974, JP-A-No. 38368/1972).
In the method of burning liquid fuel directly gasified using a pot, it is difficult to quickly increase combustion until the combustion chamber is sufficiently warmed after the fuel is ignited. Consequently, it takes time before such oil stoves radiate heat satisfactorily after the fuel is ignited. In the case of the wick-type burning method, the range over which combustion can be adjusted is small and, depending on atmospheric conditions and the room size, it may be impossible to obtain ideal heating.
Moreover, there is generated an offensive smell from oil stoves when fuel is ignited or the flame is extinguished and this has caused oil stoves to be known for their bad odor.
From the point of safety, the flame in an oil stove has to be extinguishable as quickly as possible (e.g., according to JIS, the flame in the oil stove has to be extinguished within 10 seconds after an earthquake occurs or when it is tipped over by accident). The offensive smell generated when it is turned off therefore tends to becomes stronger.
This means the flame of an oil stove is required to be extinguished as quickly as possible after flame extinguishment is initiated. In the case of an oil stove, for instance, fuel is prevented from being vaporized from the wick or pot after the flame is extinguished and it is oxidized into aldehydes producing an irritant smell while passing through the hot combustion chamber. The problem is that the resulting strong offensive smell gives users an uncomfortable feeling.
Although there are many kinds of combustion equipment using the spray combustion method, they all allow groups of oil drops to have a wide distribution of particle sizes when they are dispersed by air; and these drops act on one another and move in different directions at different speeds.
As a result, spray combustion lacks uniformity, because oil drops insufficiently vaporized and mixed reach the front face of the flame before being enclosed in diffusion flame. The flame tends to become nonuniform, causing partial overheating to parts being heated.
Moreover, a device for spraying the oil is required and this results in high running costs such as high power cost.
20 ! 3302 In addltlon to the aforementloned dlsadvantages, the oll stoves proposed ln JP-B-No. 42018/1974 and JP-A-No.
38368/1972 cannot be seen as ensurlng contlnuous combustlon wlth safety.
SUMMARY OF THE INVENTION
The present lnventlon provldes a method of burnlng a llquld fuel ln an apparatus for burnlng llquld fuel whlch has a combustlon charnber and a llquld fuel foamer havlng a top and a bottom ln the bottom of the combustlon chamber havlng a porous element wlth only the top exposed to the lnterlor of the combus-tlon chamber, the method comprlslng the steps ofz supplylng a shallow layer of llquld fuel onto the top of the porous element;
supplylng alr for foamlng to the bottom of the porous element from beneath the porous element ln an amount to cause substan-tlally all the llquld fuel to be lmmedlately converted lnto foam at a foamlng expanslon ratlo of 5-50 tlmes; causlng the resulting foam to enter the combustlon chamber7 and supplylng combustion alr separately from the foamlng alr and mlxlng lt wlth the foam ln the combustlon chamber for burnlng the foam.
The present lnventlon also provldes an apparatus for burnlng a llquld fuel, comprlslng: a combustlon chamber havlng alr lnlet holes ln the wall thereof; an lnverted cone-shaped evaporatlng dlsh openlng upwardly lnto the combustlon chamber;
a llquld fuel foamer lncludlng a porous element havlng a top and a bottom and dlsposed beneath and havlng only the top ln commu-nlcatlon wlth the bottom of sald evaporatlng dlsh, and a foamlng 4a 2 0 ~ 3 3 0 2 27257-12 alr æupply pipe dlrected to the bottom of sald porous element; a fuel supply plpe openlng lnto the bottom of sald combustlon chamber and onto the evaporatlng dlsh; and a closed ~acket surroundlng the outslde of sald combustlon chamber and havlng means for supplylng Gombustlon alr therelnto and lnto sald combustlon chamber through sald inlet holes.
~RIEF DESCRIPTI~N OF THE DRAWINGS
Flgure 1 ls a vertlcal sectlonal vlew of a burner embodylng the present lnventlon.
Flgure 2 ls a vertlcal sectlonal vlew of another burner embodylng the present lnventlon.
Flgure 3 ls a top vlew of Flgure 2.
Fl~ure 4 ls a dlagram lllustratlng a combustlon state.
2~3~
Figure 5 is a diagram illustrating an apparatus for controlling the amount of combustion by vertically moving a liquid level adjusting tank.
Figure 6 is a diagram illustrating an apparatus for controlling the amount of combustion by vertically adjusting a air feeder.
Figure 7 is a diagram illustrating a method of extinguishing a flame.
Figure 8 is a chart showing the ranges over which the amount of combustion can be varied by adjusting the amount of air supplied to the air feeder at different liquid levels.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is intended to provide a method of forming liquid fuel into bubbles and continuously burning it in a combustion chamber in order to adjust the amount of combustion, to prevent the generation of offensive smells at the time of ignition and after the flame is extinguished and to realize flame uniformity. The present invention is particularly effective when it is applied to oil stoves.
"Bubbles" is used in the present specification as a general term meaning both dispersed bubbles consisting of numerous bubbles of air or oxygen which have floated to the surface of a liquid and foam consisting of bubbles separated by thin liquid films.
_ 2~1~302 The method of burning liquid fuel in the form of foam or dispersed bubbles is characterized in that the contact area of the fuel with air can be increased hundreds of times in a condition different from heretofore.
Moreover, it has the effects of increasing the evaporation and diffusion coefficients, reducing the partial vapor pressure of the fuel on the boundary between air and liquid, and further promoting the reaction between evaporation and combustion.
A description will subsequently be given of the present invention with reference to the accompanying drawings.
Figure l is a vertical sectional view of an embodiment of the present invention. In Figure l, numeral 4 denotes a porous element (hereinafter called the air feeder) which functions as a fuel foamer and 26 an evaporating dish. Fuel is supplied from a fuel tank 19 via a pump 25 and a supply pipe 6 to a combustion chamber 1.
The evaporating dish 26 and the air feeder are disposed under the combustion chamber 1. The combustion chamber 1 is provided with a closed jacket 27 for supplying combustion air. The positional relationship between the air feeder 4 and the evaporating dish 26 is such that the surface of the air feeder 4 and the lower end of the evaporating dish 26 may be at the same level or different in level.
~ p~
'~Porous element' is used herein as a general term meaning capillaries, cloth, particle layer, porous plate having holes, sinter metal, porous ceramic or the like.
Liquid fuel is supplied to the evaporating dish 26 on the air feeder 4. When air is blown in through an air supply pipe 7, the fuel (kerosine, light oil or the like) bubbles. The fuel in the form of foam is then ignited by an igniting heater 28 and burned. The amount of combustion air required for complete combustion is separately supplied from a supply pipe 8 via the closed jacket 27 to cause continuous combustion. Numeral 14 denotes a flame.
The fuel is supplied via the fuel supply pipe 6 and the generation of bubbles is increased by increasing the amount of air supplied from the air supply pipe 7. The amount of combustion can readily be increased by increasing the amount of air supplied from the combustion air pipe 8.
As the amount of gas (air) supplied from the air supply pipe 7 is increased while the amount of fuel thus supplied is kept constant, the flame grows.
The aforementioned results seem to derive from the fact that the amount of the liquid fuel vaporized is so improved as to increase the amount of combustion due to the following effects: an increase in the vaporization surface area of the liquid fuel as the bubbling of the fuel is promoted, an increase in a liquid-to-gas diffùsion coefficient, and a decrease in partial fuel vapor pressure -on the liquid-gas boundary surface. It also becomes possible to make the combustion chamber 1 compact.
Since liquid fuel is formed into bubbles before being ignited according to the present invention, it can easily be ignited simply by directly contacting an ignition source with the bubbled fuel.
When the flame is to be extinguished, the supply of fuel to the combustion chamber 1 is stopped first and then the fuel left in the combustion chamber is bubbled before being burned, so that the time required until the fire is extinguished after the supply of fuel is stopped can be shortened. In addition, no offensive smells are produced.
Since fuel that has been once bubbled is burned, the amount of combustion and the combustion characteristics such as the flame shape are freely controllable by regulating the amount of air blown from the air supply pipe 7, the amount of fuel supplied, and the amount of air supplied from the air supply pipe 8. Moreover, instant heat generation and combustion free of any offensive smell, that have been unattainable by the prior art oil stoves, become possible.
A description will subsequently be given of the reason for the supply of air separately from the combustion air pipe 8 according to the present invention.
The bubbling expansion ratio (apparent volume/liquid fuel volume in the mixture of liquid and gas) 2 ~
-of the bubbles obtained only from liquid fuel such as kerosine, light oil or the like normally ranges from approximately 5 to 50 times. However, the air expansion ratio required for complete combustion is approximately 9,000 times and the amount of air within the bubbles is far too small.
Notwithstanding, some air supplied from the air supply pipe 7 will not be left in the bubbles but directly utilizable for combustion. The amount of air supplied from the combustion air pipe 8 should preferably be in the range of approximately 60 - 250% of the theoretical amount of combustion air.
The reason for setting the lower limit at 60%
will be explained.
During a stable combustion period in the normal state, stable combustion generally continues unless liquid fuel above the air feeder 4 is blown off by the air supplied from the air supply pipe 7. In other words, 60%
indicates a minimum flow rate of air from the combustion air pipe 8 for maintaining an optimum combustion state by increasing the flow rate of air from the air supply pipe 7 up to a stable combustion limit.
The reason for setting the upper limit at 250%
will now be explained.
In a method of burning liquid fuel in the form of bubbles a stable formation of bubbles is reqùired particularly during a transition period up to the time that 2~3~
_, stable combustion is obtained after the flame is ignited.
In other words, 250% as the upper limit indicates a minimum flow rate of air from the combustion air pipe 8 when the amount of air from the air supply pipe 7 is set at the minimum value required for the stable formation of foam.
It is also possible to promote the combustive reaction by adding a polymer or a surface active agent to liquid fuel to increase the bubbling expansion ratio.
When the combustion of bubbles is utilized for burner combustion for heating an object to be heated, there are still some problems in view of making uniform the cell size of the foam and stabilizing the foaming properties if a liquid fuel other than light oil whose temperature is lower than the boiling point is used alone to generate foam. Consequently, the liquid fuel is mixed with a foaming agent such as a polymer, a surface active agent, silicon resin or the mixture thereof, or light oil having good foaming properties. The surface viscosity is increased thereby, whereas surface tension is decreased, so that the foaming properties are improved. The stable formation of foam thus becomes possible and the combustion of foam jetted from the burner promotes a stable uniform flame with the effect of preventing local heating of parts material to be heated.
[Embodiments]
An air feeder 4 for generating foam and dispèrsed bubbles of liquid fuel and a fuel supply pipe 6 were 2~33~
provided under a combustion chamber 1 and a air supply pipe 7 was connected to the air feeder 4 to form a foam generating zone a. A number of combustion air inlet openings 9 were provided in the upper side portion of the combustion chamber to form a combustion zone b where liquid fuel was burned. The air feeder 4 comprised a porous element having a foaming function, the bottom being pot-shaped.
In operation, 80 e/min of combustion air was supplied from a combustion air supply pipe 8 via a closed jacket 27 and the air inlet openings 9 into the combustion chamber 1. While approximately 0.8 e/min of air was sent to the air supply pipe 7, 0.5 e/H of fuel (kerosine) having a temperature of 2C was subsequently supplied from a fuel tank 19 via the supply pipe 6 to the combustion chamber 1.
Bubbles of the fuel were generated on the air feeder (porous plate of sintered metal) and rose up to an igniting heater 28 where it was ignited with a red hot Nichrome wire.
The combustion state at this time was such that the mixture of the fuel with the combustion air was promoted in a flame stabilizer 30 to the extent that a blue-white flame extended upward in the flame stabilizer 30, i.e., complete combustion was realized. The time required for the flame to be produced in the upper portion of the flame stabilizer 30 after ignition was as short as 20 seconds.
2~3~
As the amount of air from the combustion air supply pipe 8 was decreased, the length of the flame became gradually longer and the flame began to show an orange color.
When the amount of air from the air supply pipe 7 was gradually increased in that combustion state to promote the foaming of the fuel, the length of the flame grew longer and the color thereof changed to blue-white.
However, the amount of the fuel being supplied was unable to keep up with the operation and the length of the flame became short. The reason for this seems attributable to the fact that the amount of combustion increases temporarily as the promotion of foaming the liquid fuel increases the amount of fuel being vaporized, thus causing the residence time of the fuel in the form of liquid in the combustion chamber to become shorter.
Subsequently, the amount of fuel being supplied was increased up to 1.0 e/H, whereas the amount of combustion air was set at 160 e/min. The flame grew to become blue-white instantly on the flame port plate and stable combustion was continued.
When the supply of the fuel was stopped, the combustion of the fuel left in the combustion chamber was immediately terminated because of bubbling combustion. The fire was completely extinguished when the supply of air from the air supply pipe was suspended. No offensive smell was produced at that time.
2~3~2 The stabilizer is constituted with a cylindrical skeleton 33 fitted to the underside of a baffle plate 32 having holes bored therein.The stabilizer is set coaxially with the porous element.
Although a porous plate with holes having a predetermined diameter was used as the air feeder 4 in this experiment, use can also be made of capillaries, a cloth, a particle layer or an air feeding method in combination therewith to generate bubbles. However, the material and shape of such a porous element are not limited to those described in the embodiment shown.
Another embodiment of the present invention will subsequently be described.
In Figures 2 and 3, numeral 1 denotes a combustion chamber, 2 a foam gathering cylinder, 3 an orifice, and 4 an air feeder. A fuel supply pipe 6 for supplying liquid fuel is connected to the underside of the foam gathering cylinder 2.
A foaming air supply pipe 7 is connected to the lower portion of the air feeder 4 so that gas such as air can be supplied from the outside. Numeral 8 denotes an air supply pipe, and 9 secondary air supply holes.
The orifice is located in the lower portion of the combustion chamber 1, which is a cylindrical or polygonal body and provided with a number of combustion air inlet openings.
-The bubbled fuel is introduced from the foam gathering cylinder 2 into the orifice before being supplied to the combustion chamber 1. The air contained in the foam and what is supplied from the air inlet openings 9 make the fuel readily burn with its flame formed thereabove.
Figure 4 shows a combustion state of liquid fuel according to the present invention. Reference character h denotes the height of the foam, whereas numeral 11 denotes fuel, 12 foaming air, and 13 combustion air. The air feeder 4 is made of sintered metal, porous ceramic or the like. The liquid fuel supplied to the foam gathering cylinder 2 is caused to readily foam by the fine air current jetted out of the air feeder 4.
The present invention is intended to provide a method and apparatus for freely controlling the amount of combustion of fuel in the form of bubbles. More specifically, the method is intended to control the amount of combustion by changing the level of the liquid fuel on the air feeder installed inside the foam gathering cylinder in the apparatus for burning the liquid fuel in the form of bubbles.
If the liquid level z of the fuel on the air feeder 4 installed inside the foam gathering cylinder 2 is increased, the amount of combustion increases as the fuel rising through the foam gathering cylinder 2 and supplied to the combustion chamber 1 increases to cause an increase in the thickness of the liquid film of foam even though the 2 ~
amount of air supplied from the foaming air supply pipe 7 is kept constant.
On the contrary, if the liquid level is decreased, the generation of foam is also decreased as is the amount of combustion.
A detailed description will subsequently be given of a method of controlling the liquid level z of the liquid fuel on the air feeder 4.
Figure 5 shows an apparatus for controlling the combustion of liquid fuel by vertically moving a small tank having a built-in float to change the liquid level in the foam gathering cylinder.
A liquid level regulating tank 16 is connected via a flexible hose 14 to a fuel supply pipe 6. The liquid level regulating tank 16 has a built-in float 17 and is provided with a liquid reservoir 15 and an air vent hole 18, whereas a fuel hose 20 from a fuel tank l9 is connected to the liquid level regulating tank 16, the fuel hose being fitted with a fuel flow rate regulating valve 21.
At some point in time the level of fuel flowing into the liquid level regulating tank 16 reaches a preset position as the fuel supplied to the air feeder 4 flows backward when the supply of fuel from the fuel tank 19 and the liquid level are decreased. Then the liquid regulating tank functions to shut a needle valve 23 provided on the surface of the float by making use of the buoyant ~orce 2~ ~3~
.
acting on the float 17 and so suspend the supply of fuel from the fuel tank.
The liquid level regulating tank 16 and the fuel supply pipe 6 are coupled via the flexible hose 14 and they S communicate with each other. When the amount of combustion is increased, a liquid level regulating tank elevator 22 is used to raise the position of the liquid level regulating tank.
At this time, the balance between the liquid level inside the combustion chamber and that in the liquid level regulating tank 16 is upset and fuel is supplied to the combustion chamber therefrom. The float 17 then descends while opening the needle valve 23 widely. Fuel is thus supplied from the fuel tank 19. When the amount of combustion in the present state is decreased, the position of the liquid level tank 16 is lowered from the present position, At this instant, fuel flows backward from the foam gathering cylinder 2 to the liquid level regulating tank 16 and the float 17 ascends, whereas the needle vale 23 is shut. The supply of fuel from the fuel tank is suspended.
While combustion is continued, the fuel that has flowed backward into the liquid level regulating tank decreases and when its level reaches what has been preset, the float descends and the supply of fuel from the fuel tank is reopened.
When the flame is to be extinguished, the position of the liquid level regulating tank is lowered until the fuel level in the foam gathering cylinder is located below the lowermost portion of the hole of the air feeder to move fuel to the liquid level regulating tank in an instant.
The fuel that has been caused to flow in is temporarily stored in the liquid reservoir 15. At the time of ignition, the liquid level regulating tank is raised by the elevator 22 up to the liquid level z corresponding to the required amount of foam to be generated.
Figure 6 shows another apparatus embodying the present invention wherein combustion is controlled by elevating a air feeder 4 to change the liquid level of liquid fuel on the air feeder.
A foaming air supply pipe 7 is fitted to the air feeder 4 provided in a foam gathering cylinder 2 coupled to the lower portion of a combustion chamber 1.
The air supply pipe 7 is equipped with an elevator 22 for vertically moving the air feeder and a desired liquid level can be set manually or by the operation of a motor.
A fuel supply pipe 6 is fitted to the lower portion of the foam gathering cylinder 2 and also coupled to a liquid level regulating tank 16.
The liquid level regulating tank 16 has a bùilt-in float 17, whereas fuel from a fuel tank l9 is led by a 2~3~
fuel hose 20, whereby fuel is supplied when a needle valve 23 opens/shuts as the float 17 moves vertically.
A method of regulating the liquid level using this apparatus will subsequently be described.
The liquid level regulating tank 16 is designed to keep the liquid level in the air feeder 4 at a predetermined height at all times during combustion and to continuously replenish the fuel to the extent that the liquid level in the air feeder lowers because of combustion. Since the liquid level regulating tank 16 and the air feeder 4 are coupled together by means of a fuel coupling pipe (flexible hose) 14, the liquid levels in both of them are set equal.
When the amount of combustion in the present state is decrease in this apparatus, the air feeder 4 is raised from the present position. The distance between the air feeder 4 and the liquid fuel level within the foam gathering cylinder 2 is shortened, i.e., the liquid level z is lowered and the amount of bubbles to be generated is decreased. The amount of combustion is also decreased.
When the air feeder 4 is lowered, on the contrary, the liquid level is raised and the amount of foam to be generated is increased. The amount of combustion is also increased.
When the flame is to be extinguished, the generation of foam is stopped. With the suspension of the supply of foaming gas to the air feeder 4, the liquid fuel 2 ~
in the lower portion of the foam gathering cylinder 2 is caused to flow via the hole of the air feeder into the air feeder 4 and further the air supply pipe 7. A pressure drop is therefore increased at the time of the next turn-on and gas may not be stably supplied.
Therefore, when the flame is to be extinguishedthe whole air feeder 4 is raised from the liquid fuel area in the foam gathering cylinder to be exposed above the liquid fuel and stop the supply of gas, while the supply of gas to the air feeder 4 is continued. As shown in Figure 7, the air feeder 4 is raised until it contacts the orifice 3 at the entrance of the combustion chamber and the flame is quickly extinguished.
At the time of ignition, foaming gas is supplied to the porous element as it is lowered and immersed in the liquid fuel.
A description will further be given, as still another embodiment of the present invention, of a method of controlling the amount of combustion by changing the flow rate of gas supplied to the air feeder while the liquid level in the air feeder is kept constant.
When the flow rate of foaming air 12 is increased while the liquid level z of liquid fuel in the air feeder 4 installed within the foam gathering cylinder 2 of Figure 4 is kept constant, the amount of foam 5 generated in the foam gathering cylinder 2, i.e., the amount of liquid fuel for use in forming bubbles to be supplied to the combustion - 2 ~ J
chamber 1 is increased. The amount of combustion is thus increased. When the flow rate of foaming air 12 is decreased, the amount of foam 5 generated is decreased.
The amount of combustion is therefore decreased.
A description will further be given, as still another embodiment of the present invention, of a method of controlling combustion as a combination of controlling the liquid level of liquid fuel in the air feeder installed in the foam gathering cylinder and of controlling the flow rate of gas supplied to the air feeder When it is desired to enlarge the range over which the amount of combustion can be adjusted in a single combustion chamber, the characteristics of the amount of combustion shown in Figure 8 are utilized to facilitate the control of two factors: the liquid level and the flow rate of gas.
A specific embodiment of this case will be described with reference to Figures 5 and 8.
With the liquid level z of liquid fuel in the air feeder being 60 mm and foaming air 12 at 3.0 e/min, the amount of combustion was 2.0 e/H in terms of the consumption of kerosine while stable combustion was continued.
When the liquid level was changed to 20 mm under the same conditions, the consumption of kerosine decreased to 0.6 ~/H. When foaming air 12 was decreased to 1.5 ~/min ~ $
J
under the same conditions, the consumption of kerosine decreased to 0.1 e/H.
By controlling the two factors in this way, the range of the amount of combustion can be widened. However, the present invention is not limited to the method of controlling these factors.
TITLE OF THE INVENTION
Method and apparatus for burning liquid fuel BACKGROUND OF THE INVENTION
1. Field of the invention The present invention relates to a method and apparatus for burning liquid fuel in a wide range of applications from household oil stoves up to industrial furnaces.
2. Description of the prior art A heretofore known practice is to burn liquid fuel either directly gasified or as finely vaporized by an atomizer.
The former method of burning the directly gasified fuel is widely used in general household oil stoves, typical of which are a pot type (JU-A-No.
35713/1983), a wick type (JP-A-Nos. 203307/1983 and 64134/1985) and a vaporization type (JIS 3030).
The pot type employs a burner bowl on which fuel is vaporized before being burned and is equipped with a combination of vaporization and combustion units.
In the case of the vaporization type, fuel is vaporized in a vaporization chamber or pipe and then burned in a combustion unit, the vaporization unit being separated from the combustion unit.
Although the method of burning gasified fuel is used in some household oil stoves, it is more generally used in industrial furnaces, boilers and the like. This 201330~
_ - 2 burning method is designed to promote vaporization and combustion reaction by gasifying liquid fuel into fine oil drops to increase the contact area of each drop with air.
Oil burners generally in use are adapted to burn fuel by means of a rotary burner, jet burner (vaporization spray, air spray and mechanical spray), special burner (gun-type high-pressure spray and low pressure spray) or the like. There are also examples having a kind of ignition device for igniting liquid fuel in the form of foam (JP-B-No. 42018/1974, JP-A-No. 38368/1972).
In the method of burning liquid fuel directly gasified using a pot, it is difficult to quickly increase combustion until the combustion chamber is sufficiently warmed after the fuel is ignited. Consequently, it takes time before such oil stoves radiate heat satisfactorily after the fuel is ignited. In the case of the wick-type burning method, the range over which combustion can be adjusted is small and, depending on atmospheric conditions and the room size, it may be impossible to obtain ideal heating.
Moreover, there is generated an offensive smell from oil stoves when fuel is ignited or the flame is extinguished and this has caused oil stoves to be known for their bad odor.
From the point of safety, the flame in an oil stove has to be extinguishable as quickly as possible (e.g., according to JIS, the flame in the oil stove has to be extinguished within 10 seconds after an earthquake occurs or when it is tipped over by accident). The offensive smell generated when it is turned off therefore tends to becomes stronger.
This means the flame of an oil stove is required to be extinguished as quickly as possible after flame extinguishment is initiated. In the case of an oil stove, for instance, fuel is prevented from being vaporized from the wick or pot after the flame is extinguished and it is oxidized into aldehydes producing an irritant smell while passing through the hot combustion chamber. The problem is that the resulting strong offensive smell gives users an uncomfortable feeling.
Although there are many kinds of combustion equipment using the spray combustion method, they all allow groups of oil drops to have a wide distribution of particle sizes when they are dispersed by air; and these drops act on one another and move in different directions at different speeds.
As a result, spray combustion lacks uniformity, because oil drops insufficiently vaporized and mixed reach the front face of the flame before being enclosed in diffusion flame. The flame tends to become nonuniform, causing partial overheating to parts being heated.
Moreover, a device for spraying the oil is required and this results in high running costs such as high power cost.
20 ! 3302 In addltlon to the aforementloned dlsadvantages, the oll stoves proposed ln JP-B-No. 42018/1974 and JP-A-No.
38368/1972 cannot be seen as ensurlng contlnuous combustlon wlth safety.
SUMMARY OF THE INVENTION
The present lnventlon provldes a method of burnlng a llquld fuel ln an apparatus for burnlng llquld fuel whlch has a combustlon charnber and a llquld fuel foamer havlng a top and a bottom ln the bottom of the combustlon chamber havlng a porous element wlth only the top exposed to the lnterlor of the combus-tlon chamber, the method comprlslng the steps ofz supplylng a shallow layer of llquld fuel onto the top of the porous element;
supplylng alr for foamlng to the bottom of the porous element from beneath the porous element ln an amount to cause substan-tlally all the llquld fuel to be lmmedlately converted lnto foam at a foamlng expanslon ratlo of 5-50 tlmes; causlng the resulting foam to enter the combustlon chamber7 and supplylng combustion alr separately from the foamlng alr and mlxlng lt wlth the foam ln the combustlon chamber for burnlng the foam.
The present lnventlon also provldes an apparatus for burnlng a llquld fuel, comprlslng: a combustlon chamber havlng alr lnlet holes ln the wall thereof; an lnverted cone-shaped evaporatlng dlsh openlng upwardly lnto the combustlon chamber;
a llquld fuel foamer lncludlng a porous element havlng a top and a bottom and dlsposed beneath and havlng only the top ln commu-nlcatlon wlth the bottom of sald evaporatlng dlsh, and a foamlng 4a 2 0 ~ 3 3 0 2 27257-12 alr æupply pipe dlrected to the bottom of sald porous element; a fuel supply plpe openlng lnto the bottom of sald combustlon chamber and onto the evaporatlng dlsh; and a closed ~acket surroundlng the outslde of sald combustlon chamber and havlng means for supplylng Gombustlon alr therelnto and lnto sald combustlon chamber through sald inlet holes.
~RIEF DESCRIPTI~N OF THE DRAWINGS
Flgure 1 ls a vertlcal sectlonal vlew of a burner embodylng the present lnventlon.
Flgure 2 ls a vertlcal sectlonal vlew of another burner embodylng the present lnventlon.
Flgure 3 ls a top vlew of Flgure 2.
Fl~ure 4 ls a dlagram lllustratlng a combustlon state.
2~3~
Figure 5 is a diagram illustrating an apparatus for controlling the amount of combustion by vertically moving a liquid level adjusting tank.
Figure 6 is a diagram illustrating an apparatus for controlling the amount of combustion by vertically adjusting a air feeder.
Figure 7 is a diagram illustrating a method of extinguishing a flame.
Figure 8 is a chart showing the ranges over which the amount of combustion can be varied by adjusting the amount of air supplied to the air feeder at different liquid levels.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is intended to provide a method of forming liquid fuel into bubbles and continuously burning it in a combustion chamber in order to adjust the amount of combustion, to prevent the generation of offensive smells at the time of ignition and after the flame is extinguished and to realize flame uniformity. The present invention is particularly effective when it is applied to oil stoves.
"Bubbles" is used in the present specification as a general term meaning both dispersed bubbles consisting of numerous bubbles of air or oxygen which have floated to the surface of a liquid and foam consisting of bubbles separated by thin liquid films.
_ 2~1~302 The method of burning liquid fuel in the form of foam or dispersed bubbles is characterized in that the contact area of the fuel with air can be increased hundreds of times in a condition different from heretofore.
Moreover, it has the effects of increasing the evaporation and diffusion coefficients, reducing the partial vapor pressure of the fuel on the boundary between air and liquid, and further promoting the reaction between evaporation and combustion.
A description will subsequently be given of the present invention with reference to the accompanying drawings.
Figure l is a vertical sectional view of an embodiment of the present invention. In Figure l, numeral 4 denotes a porous element (hereinafter called the air feeder) which functions as a fuel foamer and 26 an evaporating dish. Fuel is supplied from a fuel tank 19 via a pump 25 and a supply pipe 6 to a combustion chamber 1.
The evaporating dish 26 and the air feeder are disposed under the combustion chamber 1. The combustion chamber 1 is provided with a closed jacket 27 for supplying combustion air. The positional relationship between the air feeder 4 and the evaporating dish 26 is such that the surface of the air feeder 4 and the lower end of the evaporating dish 26 may be at the same level or different in level.
~ p~
'~Porous element' is used herein as a general term meaning capillaries, cloth, particle layer, porous plate having holes, sinter metal, porous ceramic or the like.
Liquid fuel is supplied to the evaporating dish 26 on the air feeder 4. When air is blown in through an air supply pipe 7, the fuel (kerosine, light oil or the like) bubbles. The fuel in the form of foam is then ignited by an igniting heater 28 and burned. The amount of combustion air required for complete combustion is separately supplied from a supply pipe 8 via the closed jacket 27 to cause continuous combustion. Numeral 14 denotes a flame.
The fuel is supplied via the fuel supply pipe 6 and the generation of bubbles is increased by increasing the amount of air supplied from the air supply pipe 7. The amount of combustion can readily be increased by increasing the amount of air supplied from the combustion air pipe 8.
As the amount of gas (air) supplied from the air supply pipe 7 is increased while the amount of fuel thus supplied is kept constant, the flame grows.
The aforementioned results seem to derive from the fact that the amount of the liquid fuel vaporized is so improved as to increase the amount of combustion due to the following effects: an increase in the vaporization surface area of the liquid fuel as the bubbling of the fuel is promoted, an increase in a liquid-to-gas diffùsion coefficient, and a decrease in partial fuel vapor pressure -on the liquid-gas boundary surface. It also becomes possible to make the combustion chamber 1 compact.
Since liquid fuel is formed into bubbles before being ignited according to the present invention, it can easily be ignited simply by directly contacting an ignition source with the bubbled fuel.
When the flame is to be extinguished, the supply of fuel to the combustion chamber 1 is stopped first and then the fuel left in the combustion chamber is bubbled before being burned, so that the time required until the fire is extinguished after the supply of fuel is stopped can be shortened. In addition, no offensive smells are produced.
Since fuel that has been once bubbled is burned, the amount of combustion and the combustion characteristics such as the flame shape are freely controllable by regulating the amount of air blown from the air supply pipe 7, the amount of fuel supplied, and the amount of air supplied from the air supply pipe 8. Moreover, instant heat generation and combustion free of any offensive smell, that have been unattainable by the prior art oil stoves, become possible.
A description will subsequently be given of the reason for the supply of air separately from the combustion air pipe 8 according to the present invention.
The bubbling expansion ratio (apparent volume/liquid fuel volume in the mixture of liquid and gas) 2 ~
-of the bubbles obtained only from liquid fuel such as kerosine, light oil or the like normally ranges from approximately 5 to 50 times. However, the air expansion ratio required for complete combustion is approximately 9,000 times and the amount of air within the bubbles is far too small.
Notwithstanding, some air supplied from the air supply pipe 7 will not be left in the bubbles but directly utilizable for combustion. The amount of air supplied from the combustion air pipe 8 should preferably be in the range of approximately 60 - 250% of the theoretical amount of combustion air.
The reason for setting the lower limit at 60%
will be explained.
During a stable combustion period in the normal state, stable combustion generally continues unless liquid fuel above the air feeder 4 is blown off by the air supplied from the air supply pipe 7. In other words, 60%
indicates a minimum flow rate of air from the combustion air pipe 8 for maintaining an optimum combustion state by increasing the flow rate of air from the air supply pipe 7 up to a stable combustion limit.
The reason for setting the upper limit at 250%
will now be explained.
In a method of burning liquid fuel in the form of bubbles a stable formation of bubbles is reqùired particularly during a transition period up to the time that 2~3~
_, stable combustion is obtained after the flame is ignited.
In other words, 250% as the upper limit indicates a minimum flow rate of air from the combustion air pipe 8 when the amount of air from the air supply pipe 7 is set at the minimum value required for the stable formation of foam.
It is also possible to promote the combustive reaction by adding a polymer or a surface active agent to liquid fuel to increase the bubbling expansion ratio.
When the combustion of bubbles is utilized for burner combustion for heating an object to be heated, there are still some problems in view of making uniform the cell size of the foam and stabilizing the foaming properties if a liquid fuel other than light oil whose temperature is lower than the boiling point is used alone to generate foam. Consequently, the liquid fuel is mixed with a foaming agent such as a polymer, a surface active agent, silicon resin or the mixture thereof, or light oil having good foaming properties. The surface viscosity is increased thereby, whereas surface tension is decreased, so that the foaming properties are improved. The stable formation of foam thus becomes possible and the combustion of foam jetted from the burner promotes a stable uniform flame with the effect of preventing local heating of parts material to be heated.
[Embodiments]
An air feeder 4 for generating foam and dispèrsed bubbles of liquid fuel and a fuel supply pipe 6 were 2~33~
provided under a combustion chamber 1 and a air supply pipe 7 was connected to the air feeder 4 to form a foam generating zone a. A number of combustion air inlet openings 9 were provided in the upper side portion of the combustion chamber to form a combustion zone b where liquid fuel was burned. The air feeder 4 comprised a porous element having a foaming function, the bottom being pot-shaped.
In operation, 80 e/min of combustion air was supplied from a combustion air supply pipe 8 via a closed jacket 27 and the air inlet openings 9 into the combustion chamber 1. While approximately 0.8 e/min of air was sent to the air supply pipe 7, 0.5 e/H of fuel (kerosine) having a temperature of 2C was subsequently supplied from a fuel tank 19 via the supply pipe 6 to the combustion chamber 1.
Bubbles of the fuel were generated on the air feeder (porous plate of sintered metal) and rose up to an igniting heater 28 where it was ignited with a red hot Nichrome wire.
The combustion state at this time was such that the mixture of the fuel with the combustion air was promoted in a flame stabilizer 30 to the extent that a blue-white flame extended upward in the flame stabilizer 30, i.e., complete combustion was realized. The time required for the flame to be produced in the upper portion of the flame stabilizer 30 after ignition was as short as 20 seconds.
2~3~
As the amount of air from the combustion air supply pipe 8 was decreased, the length of the flame became gradually longer and the flame began to show an orange color.
When the amount of air from the air supply pipe 7 was gradually increased in that combustion state to promote the foaming of the fuel, the length of the flame grew longer and the color thereof changed to blue-white.
However, the amount of the fuel being supplied was unable to keep up with the operation and the length of the flame became short. The reason for this seems attributable to the fact that the amount of combustion increases temporarily as the promotion of foaming the liquid fuel increases the amount of fuel being vaporized, thus causing the residence time of the fuel in the form of liquid in the combustion chamber to become shorter.
Subsequently, the amount of fuel being supplied was increased up to 1.0 e/H, whereas the amount of combustion air was set at 160 e/min. The flame grew to become blue-white instantly on the flame port plate and stable combustion was continued.
When the supply of the fuel was stopped, the combustion of the fuel left in the combustion chamber was immediately terminated because of bubbling combustion. The fire was completely extinguished when the supply of air from the air supply pipe was suspended. No offensive smell was produced at that time.
2~3~2 The stabilizer is constituted with a cylindrical skeleton 33 fitted to the underside of a baffle plate 32 having holes bored therein.The stabilizer is set coaxially with the porous element.
Although a porous plate with holes having a predetermined diameter was used as the air feeder 4 in this experiment, use can also be made of capillaries, a cloth, a particle layer or an air feeding method in combination therewith to generate bubbles. However, the material and shape of such a porous element are not limited to those described in the embodiment shown.
Another embodiment of the present invention will subsequently be described.
In Figures 2 and 3, numeral 1 denotes a combustion chamber, 2 a foam gathering cylinder, 3 an orifice, and 4 an air feeder. A fuel supply pipe 6 for supplying liquid fuel is connected to the underside of the foam gathering cylinder 2.
A foaming air supply pipe 7 is connected to the lower portion of the air feeder 4 so that gas such as air can be supplied from the outside. Numeral 8 denotes an air supply pipe, and 9 secondary air supply holes.
The orifice is located in the lower portion of the combustion chamber 1, which is a cylindrical or polygonal body and provided with a number of combustion air inlet openings.
-The bubbled fuel is introduced from the foam gathering cylinder 2 into the orifice before being supplied to the combustion chamber 1. The air contained in the foam and what is supplied from the air inlet openings 9 make the fuel readily burn with its flame formed thereabove.
Figure 4 shows a combustion state of liquid fuel according to the present invention. Reference character h denotes the height of the foam, whereas numeral 11 denotes fuel, 12 foaming air, and 13 combustion air. The air feeder 4 is made of sintered metal, porous ceramic or the like. The liquid fuel supplied to the foam gathering cylinder 2 is caused to readily foam by the fine air current jetted out of the air feeder 4.
The present invention is intended to provide a method and apparatus for freely controlling the amount of combustion of fuel in the form of bubbles. More specifically, the method is intended to control the amount of combustion by changing the level of the liquid fuel on the air feeder installed inside the foam gathering cylinder in the apparatus for burning the liquid fuel in the form of bubbles.
If the liquid level z of the fuel on the air feeder 4 installed inside the foam gathering cylinder 2 is increased, the amount of combustion increases as the fuel rising through the foam gathering cylinder 2 and supplied to the combustion chamber 1 increases to cause an increase in the thickness of the liquid film of foam even though the 2 ~
amount of air supplied from the foaming air supply pipe 7 is kept constant.
On the contrary, if the liquid level is decreased, the generation of foam is also decreased as is the amount of combustion.
A detailed description will subsequently be given of a method of controlling the liquid level z of the liquid fuel on the air feeder 4.
Figure 5 shows an apparatus for controlling the combustion of liquid fuel by vertically moving a small tank having a built-in float to change the liquid level in the foam gathering cylinder.
A liquid level regulating tank 16 is connected via a flexible hose 14 to a fuel supply pipe 6. The liquid level regulating tank 16 has a built-in float 17 and is provided with a liquid reservoir 15 and an air vent hole 18, whereas a fuel hose 20 from a fuel tank l9 is connected to the liquid level regulating tank 16, the fuel hose being fitted with a fuel flow rate regulating valve 21.
At some point in time the level of fuel flowing into the liquid level regulating tank 16 reaches a preset position as the fuel supplied to the air feeder 4 flows backward when the supply of fuel from the fuel tank 19 and the liquid level are decreased. Then the liquid regulating tank functions to shut a needle valve 23 provided on the surface of the float by making use of the buoyant ~orce 2~ ~3~
.
acting on the float 17 and so suspend the supply of fuel from the fuel tank.
The liquid level regulating tank 16 and the fuel supply pipe 6 are coupled via the flexible hose 14 and they S communicate with each other. When the amount of combustion is increased, a liquid level regulating tank elevator 22 is used to raise the position of the liquid level regulating tank.
At this time, the balance between the liquid level inside the combustion chamber and that in the liquid level regulating tank 16 is upset and fuel is supplied to the combustion chamber therefrom. The float 17 then descends while opening the needle valve 23 widely. Fuel is thus supplied from the fuel tank 19. When the amount of combustion in the present state is decreased, the position of the liquid level tank 16 is lowered from the present position, At this instant, fuel flows backward from the foam gathering cylinder 2 to the liquid level regulating tank 16 and the float 17 ascends, whereas the needle vale 23 is shut. The supply of fuel from the fuel tank is suspended.
While combustion is continued, the fuel that has flowed backward into the liquid level regulating tank decreases and when its level reaches what has been preset, the float descends and the supply of fuel from the fuel tank is reopened.
When the flame is to be extinguished, the position of the liquid level regulating tank is lowered until the fuel level in the foam gathering cylinder is located below the lowermost portion of the hole of the air feeder to move fuel to the liquid level regulating tank in an instant.
The fuel that has been caused to flow in is temporarily stored in the liquid reservoir 15. At the time of ignition, the liquid level regulating tank is raised by the elevator 22 up to the liquid level z corresponding to the required amount of foam to be generated.
Figure 6 shows another apparatus embodying the present invention wherein combustion is controlled by elevating a air feeder 4 to change the liquid level of liquid fuel on the air feeder.
A foaming air supply pipe 7 is fitted to the air feeder 4 provided in a foam gathering cylinder 2 coupled to the lower portion of a combustion chamber 1.
The air supply pipe 7 is equipped with an elevator 22 for vertically moving the air feeder and a desired liquid level can be set manually or by the operation of a motor.
A fuel supply pipe 6 is fitted to the lower portion of the foam gathering cylinder 2 and also coupled to a liquid level regulating tank 16.
The liquid level regulating tank 16 has a bùilt-in float 17, whereas fuel from a fuel tank l9 is led by a 2~3~
fuel hose 20, whereby fuel is supplied when a needle valve 23 opens/shuts as the float 17 moves vertically.
A method of regulating the liquid level using this apparatus will subsequently be described.
The liquid level regulating tank 16 is designed to keep the liquid level in the air feeder 4 at a predetermined height at all times during combustion and to continuously replenish the fuel to the extent that the liquid level in the air feeder lowers because of combustion. Since the liquid level regulating tank 16 and the air feeder 4 are coupled together by means of a fuel coupling pipe (flexible hose) 14, the liquid levels in both of them are set equal.
When the amount of combustion in the present state is decrease in this apparatus, the air feeder 4 is raised from the present position. The distance between the air feeder 4 and the liquid fuel level within the foam gathering cylinder 2 is shortened, i.e., the liquid level z is lowered and the amount of bubbles to be generated is decreased. The amount of combustion is also decreased.
When the air feeder 4 is lowered, on the contrary, the liquid level is raised and the amount of foam to be generated is increased. The amount of combustion is also increased.
When the flame is to be extinguished, the generation of foam is stopped. With the suspension of the supply of foaming gas to the air feeder 4, the liquid fuel 2 ~
in the lower portion of the foam gathering cylinder 2 is caused to flow via the hole of the air feeder into the air feeder 4 and further the air supply pipe 7. A pressure drop is therefore increased at the time of the next turn-on and gas may not be stably supplied.
Therefore, when the flame is to be extinguishedthe whole air feeder 4 is raised from the liquid fuel area in the foam gathering cylinder to be exposed above the liquid fuel and stop the supply of gas, while the supply of gas to the air feeder 4 is continued. As shown in Figure 7, the air feeder 4 is raised until it contacts the orifice 3 at the entrance of the combustion chamber and the flame is quickly extinguished.
At the time of ignition, foaming gas is supplied to the porous element as it is lowered and immersed in the liquid fuel.
A description will further be given, as still another embodiment of the present invention, of a method of controlling the amount of combustion by changing the flow rate of gas supplied to the air feeder while the liquid level in the air feeder is kept constant.
When the flow rate of foaming air 12 is increased while the liquid level z of liquid fuel in the air feeder 4 installed within the foam gathering cylinder 2 of Figure 4 is kept constant, the amount of foam 5 generated in the foam gathering cylinder 2, i.e., the amount of liquid fuel for use in forming bubbles to be supplied to the combustion - 2 ~ J
chamber 1 is increased. The amount of combustion is thus increased. When the flow rate of foaming air 12 is decreased, the amount of foam 5 generated is decreased.
The amount of combustion is therefore decreased.
A description will further be given, as still another embodiment of the present invention, of a method of controlling combustion as a combination of controlling the liquid level of liquid fuel in the air feeder installed in the foam gathering cylinder and of controlling the flow rate of gas supplied to the air feeder When it is desired to enlarge the range over which the amount of combustion can be adjusted in a single combustion chamber, the characteristics of the amount of combustion shown in Figure 8 are utilized to facilitate the control of two factors: the liquid level and the flow rate of gas.
A specific embodiment of this case will be described with reference to Figures 5 and 8.
With the liquid level z of liquid fuel in the air feeder being 60 mm and foaming air 12 at 3.0 e/min, the amount of combustion was 2.0 e/H in terms of the consumption of kerosine while stable combustion was continued.
When the liquid level was changed to 20 mm under the same conditions, the consumption of kerosine decreased to 0.6 ~/H. When foaming air 12 was decreased to 1.5 ~/min ~ $
J
under the same conditions, the consumption of kerosine decreased to 0.1 e/H.
By controlling the two factors in this way, the range of the amount of combustion can be widened. However, the present invention is not limited to the method of controlling these factors.
Claims (3)
1. A method of burning a liquid fuel in an apparatus for burning liquid fuel which has a combustion chamber and a liquid fuel foamer having a top and a bottom in the bottom of the combustion chamber having a porous element with only the top exposed to the interior of the combustion chamber, the method comprising the steps of:
supplying a shallow layer of liquid fuel onto the top of the porous element;
supplying air for foaming to the bottom of the porous element from beneath the porous element in an amount to cause substantially all the liquid fuel to be immediately converted into foam at a foaming expansion ratio of 5-50 times;
causing the resulting foam to enter the combustion chamber;
and supplying combustion air separately from the foaming air and mixing it with the foam in the combustion chamber for burning the foam.
supplying a shallow layer of liquid fuel onto the top of the porous element;
supplying air for foaming to the bottom of the porous element from beneath the porous element in an amount to cause substantially all the liquid fuel to be immediately converted into foam at a foaming expansion ratio of 5-50 times;
causing the resulting foam to enter the combustion chamber;
and supplying combustion air separately from the foaming air and mixing it with the foam in the combustion chamber for burning the foam.
2. An apparatus for burning a liquid fuel, comprising:
a combustion chamber having air inlet holes in the wall thereof;
an inverted cone-shaped evaporating dish opening upwardly into the combustion chamber;
a liquid fuel foamer including a porous element having a top and a bottom and disposed beneath and having only the top in communication with the bottom of said evaporating dish, and a foaming air supply pipe directed to the bottom of said porous element;
a fuel supply pipe opening into the bottom of said combustion chamber and onto the evaporating dish; and a closed jacket surrounding the outside of said combustion chamber and having means for supplying combustion air thereinto and into said combustion chamber through said inlet holes.
a combustion chamber having air inlet holes in the wall thereof;
an inverted cone-shaped evaporating dish opening upwardly into the combustion chamber;
a liquid fuel foamer including a porous element having a top and a bottom and disposed beneath and having only the top in communication with the bottom of said evaporating dish, and a foaming air supply pipe directed to the bottom of said porous element;
a fuel supply pipe opening into the bottom of said combustion chamber and onto the evaporating dish; and a closed jacket surrounding the outside of said combustion chamber and having means for supplying combustion air thereinto and into said combustion chamber through said inlet holes.
3. An apparatus as claimed in claim 2 further comprising a flame stabilizer in said combustion chamber and having a vertically positioned cylindrical sleeve having holes therein and in alignment with a vertical axis through the porous element.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1081237A JPH0668364B2 (en) | 1989-03-31 | 1989-03-31 | Liquid fuel combustion device |
| JP81237/1-1989 | 1989-03-31 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2013302A1 CA2013302A1 (en) | 1990-09-30 |
| CA2013302C true CA2013302C (en) | 1995-10-24 |
Family
ID=13740830
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2013302 Expired - Fee Related CA2013302C (en) | 1989-03-31 | 1990-03-29 | Method and apparatus for burning liquid fuel |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH0668364B2 (en) |
| CA (1) | CA2013302C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2049009C (en) * | 1990-03-20 | 1995-02-07 | Norio Anzawa | Method and apparatus for burning foamed liquid fuel |
| JP2755511B2 (en) * | 1992-01-30 | 1998-05-20 | 新日本製鐵株式会社 | Method and apparatus for burning liquid fuel |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5457231A (en) * | 1977-10-15 | 1979-05-08 | Sharp Corp | Burner for use in combustors |
| JPS55110907U (en) * | 1979-01-29 | 1980-08-04 | ||
| JPS56133514A (en) * | 1980-03-19 | 1981-10-19 | Matsushita Electric Ind Co Ltd | Air follow type liquid fuel burner |
| JPH0235204B2 (en) * | 1984-07-04 | 1990-08-09 | Nippon Sekyu Seisei Kk | NENSHOSOCHI |
-
1989
- 1989-03-31 JP JP1081237A patent/JPH0668364B2/en not_active Expired - Fee Related
-
1990
- 1990-03-29 CA CA 2013302 patent/CA2013302C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02259311A (en) | 1990-10-22 |
| JPH0668364B2 (en) | 1994-08-31 |
| CA2013302A1 (en) | 1990-09-30 |
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| EEER | Examination request | ||
| MKLA | Lapsed |