Introduction to the field of the invention
This invention relates to an improved oil gasification burner and a method of gasification of liquid
fuel.
Oil gasification burners find use in re-heating furnaces, boilers and furnaces of mini steel
industries.
Prior art and drawbacks
Oil gasification burners are already well known and in use. The different uses require oil gasification burners with good atomization to be economical.
It is further necessary to have pulsating free flames to be stable even if the fuels are property atomized.
Further, it is desirable to have oil gasification burners, which can start up under cold conditions and produce flames of high heat intensity.
In the known art, conventional liquid fuel burners have the main drawbacks that these produce flame with poor atomization, inadequately stable, and pulsating flames of relatively low heat intensity having cold start-up problems.
A conventional liquid fuel burner comprises of an inner pipe with a nozzle at the tip through which liquid fuel emulsion is supplied and a middle pipe fitted co-axially to the inner pipe as a dummy pipe. Combustion air is supplied through an outer pipe at a pressure of 400 to 800 mm WC The burner tip is mounted on to a refractory burner block. Liquid fuel emulsion is formed by mixing atomizing media like stream or compressed air at a pressure of 1 to 4 Kg/cm2 and liquid fuel at a pressure of 1 to 4 Kg/cm2 and the same is supplied through the inner pipe.
There is no liquid fuel gasification burner presently in use or suggested in any literature, which has all the beneficial requirements mentioned above and free of any problem.
Objects of the invention
It is therefore a principal object of the invention to propose an improved fuel oil gasification burner, which can efficiently atomize the fuel and produce a steady pulsating free flame.
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It is another object of this invention to suggest such an improved fuel oil gasification burner, which is also suited for cold start-up conditions
It is a further object of this invention to propose such a fuel oil gasification burner, which can produce flames having higher heat intensity than so far possible.
It is a still further object of this invention to propose an improved fuel oil gasification burner, which can produce soot and smoke free flame, thereby ensunng better heat content of the flame than hitherto achieved.
It is a still further object of this invention to propose such an improved fuel oil gasification burner in which almost the full calonfic valve of the fuel can be realized which has not been possible before.
It is yet another object of the invention to propose an improved method of gasification of fuel oil using fuel gas for initial start-up period only.
These and other objects of the invention will be more apparent from the following paragraphs. Brief statement of the invention
According to this invention, there is provided an improved fuel oil gasificaion burner, compnsmg a pair of co-axial tubes of which the outer tube is adapted to feed combustion air and the inner tube is adapted to feed fuel gas, the tips of the inner and outer tube terminating into an expansion zone, the region immediately next to the termination point of the tips of the said co-axial tubes being provided with a fuel-oil supply pipe for feeding liquid fuel, said fuel supply pipe having a trailing end connected down stream with the said expansion zone and a leading end terminating close to the tips of the co-axial tubes and there being provided a fuel oil inlet between said trailing end and leading end of the fuel supply pipe.
The outer tube of the co-axial tubes is provided with an inlet for combustion air.
The combustion air inlet is provided preferably at 90° to the horizontal axis of the co-axial tubes. The inner tube of the co-axial tubes has a trailing end protruding beyond that of the outer tube and is connected to a fuel gas source.
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The leading ends of both the outer tube and inner tube terminate in the form of nozzles at the same vertical axis but spaced apart such that there is an annular space between the inner wall of the outer nozzle and the outer wall of the inner nozzle.
The tip of the nozzles of the inner tube and that of the outer tube are circular in shape and configuration.
The inner tube is a long unitary piece having substantively a cylindrical cross section and a minor convergent nozzle section.
The outer tube has a relatively longer cylindrical cross section and a shorter convergent nozzle section
The different sections of the outer tube and the inner tube are such that, when assembled, not only the convergent nozzle section but also a portion of the trailing cylindrical cross section of the inner tube lies within the convergent nozzle section of the outer tube.
The expansion zone is formed of a gradually expanding tube, having the above said two nozzle tips extending into a portion of its upstream end while its downstream end terminates into an expansion chamber of a refractory block.
The said fuel supply pipe has its one end connected to the end downstream region of the expansion chamber of the said refractory block, while the other end of the fuel oil supply pipe is connected to the upstream region of the said expansion tubes, preferably in an axis vertical to the horizontal axis of the expansion tube.
The number(s) of fuel oil supply tubes, also called return tube(s) varies from 1 to 6 tubes depending on capacity and requirement.
The refractory burner block is made of high-alumina material.
According to another aspect of the invention, there is provided an improved method for the gasification of fuel oil which compnses feeding a stream of gaseous fuel and combustion air, lighting up the gaseous fuel, thereby creating suction for re-circulating the products of combustion after passing through an expansion zone, injecting fuel oil into the re-circulating stream carrying the products of combustion, allowing the fuel oil to gasify and thereby to burn thereafter and
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terminating supply of the fuel gas and continuing burning the fuel oil in the presence of combustion air.
The combustion air and fuel gas are injected through nozzle means at sufficient pressure to drag the fuel oil into an expansion zone.
Brief description of the drawings
The invention is more fully described in the accompanying drawing wherein
Figure 1 is a sketch of conventional liquid fuel burner.
Figure 2 is a sketch of oil gasification burner of the present invention.
Figure 3 is a cross sectional view along the arrow A A of Figure 2.
Detailed description of the drawings
Referring to Figure 1, the conventional liquid fuel burner comprises of an inner pipe (1) into which emulsion is supplied with a nozzle (2) at the tip and intermediate pipe (3) fitted co-axially to the inner pipe acts as dummy pipe; Outer pipe (4) into which combustion air is supplied having swirlers (5) fitted before the tip of the burner. Refractory burner block (6) is fitted at the mouth of the burner nozzle
Refernng to Figure 2, the invented burner comprises of an inner pipe (1) with a nozzle at the tip, the outer pipe (2) with nozzle (3) at the tip. These nozzles are fitted in to an expanding tube (4), which is fitted into refractory burner block (5). Tube(s) (6) is joined from refractory burner block to the exit the nozzle (3). A tube (7) is joined to this (these) tube(s) (6). Gas is supplied through the inner pipe (1) and combustion air is supplied through the outer pipe (2). The air nozzle (3) acts as injector. Due to the low pressure near the combustion air nozzle (3) products of combustion are sucked through the tube(s) (6). This tube(s) (6) is called as return tube. Liquid fuel is supplied through the tube (7) into the return tube(s) (6). Due to the high temperature of the return tube gasification of liquid fuel takes place in this tube. Numbers of return tubes are varied from 1 to 6 depending on the capacity of the burner. A typical burner according to the invention ts capable of firing fuel gases of calorific value 1200 to 15000 kcal/Nm3 and capacity of burning liquid fuel at the rate of 50 to 200 Kg/hr at a pressure of 1 to 4 Kg/ cm2. Combustion air can be supplied at a pressure of 400 to 1000 mm We and fuel gas at a pressure of 100 to 500 mm We.
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The operation/function is as follows. -
Gaseous fuel is supplied through the inner pipe with a nozzle at the tip. Combustion air is supplied through the outer pipe with nozzle tip Nozzle of the combustion air creates low pressure zone near the tip. Products of combustion passes through the expanding tube and refractory burner block. Tube(s) fitted parallel to the burner axis from burner block to the tip of the combustion air nozzle. Due to low pressure zone near the tip of the combustion air nozzle, products of combustion pass through this tube in reverse direction. This tube(s) is known as return tube. Liquid fuel connection is made to this 1ube(s).
The burner is lighted up with gaseous fuel As the products combustion passes through the return tube, it's temperature rises immediately. Lot of suction can be observed in the tube After 30-60 seconds, liquid fuel is supplied through the return tube. Due to the high temperature, gasification of oil takes place and it's combustion takes place very smoothly. Gas supply can be cut off once the liquid fuel light up takes place
It will be seen that for making the air nozzle to act as an injector the combustion air enters the convergent nozzle region 3 much ahead of the nozzle region 1 of the fuel gas pipe Air velocity increases in the annular space and sufficient suction is created at the nozzle tip to suck the hot flue gases. This vaporizes the fuel oil, which is injected in the flue gas line very efficiently.
Advantages of the invention
The oil gasification burner is capable of burning liquid fuel rapidly and completely, and producing pulsating free high thrust stable bnght flame with out soot and smoke formation; has a turn down ratio (ratio of lowest capacity of burner at which it can be operated to the rated capacity of the burner) of 16 for an excess air co-efficient between 1.0 to 1.5 and is suitable for re-heating furnaces and boilers, and compnses two co-axially mounted pipes of which inner pipes is meant for gaseous fuel and outer pipe is meant for supplying combustion air and burner block integrally fitted At the mouth of the burner with return tube(s) fitted parallel to the burner axis from the burner block to combustion air pipe tip with liquid fuel inlet connected to return tube(s), characterized in that gasification of liquid fuel is achieved suitable for cold start-up for producing high thrust pulsation free stable flames
Field trials were conducted on the invented burner. The following advantageous feature of burner have been found.
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1. Gasification of liquid fuel in the burner body itself.
2. Complete combustion, which leads to higher flame temperature and therefore better heat-
transfer.

3 Higher turn down rations of 1:6 against 1:3 for conventional burners
4 Elimination of soot and smoke formation

5. Cold start-up, stable, pulsating free, high thrust and bright flame.
6. Higher flame temperatures of 1400° C (maximum) when compared with 1250° C of the flame
produced in conventional liquid fuel burners at low furnace temperatures of less than 100° C.
7. Atomizing media like stream or compressed air is not required for atomizatren of liquid fuel.
According to another aspect of the invention, there is provided an improved method for the
gasification of fuel oil which comprises feeding fuel oil into a stream qf combustion air and
fuel gas, lighting up the gaseous fuel, re-circulating the products of combustion after passing
through an expansion zone, supplementing the products of-combustion with fuel oil £nd
allowing the fuel oil to bum thereafter, terminating supply of the futff gas and continuing
burning the fuel oil in the presence of combustion air.
The combustion air and fuel gas are injected through nozzle means at sufficient pressure to drag the fuel oil into an expansion zone
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We claim
1. An improved fuel oil gasificaion burner, comprising a pair of co-axial tubes of which the outer tube is adapted to feed combustion air and the inner tube is adapted to feed fuel gas, the tips of the inner and outer tube terminating into an expansion zone, the region immediately next to the termination point of the tips of the said co-axial tubes being provided with a fuel-oil supply pipe for feeding liquid fuel, said fuel supply pipe having a trailing end connected down stream with the said expansion zone and a leading end terminating close to the tips of the coaxial tubes and there being provided a fuel oil inlet between said trailing end and leading end of the fuel supply pipe.
2 An improved fuel oil gasificaion burner as claimed in claim 1, wherein the outer tube of the
co-axial tubes is provided with an inlet for combustion air.
3 An improved fuel oil gasificaion burner as claimed in claims land 2, wherein the combustion
air inlet is provided preferably at 90° to the horizontal axis of the co-axial tubes

4. An improved fuel oil gasificaion burner as claimed in claims 1 to 3, wherein the inner tube of
the co-axial tubes has a trailing end protruding beyond that of the outer tube and is
connected to a fuel gas source.
5. An improved fuel oil gasificaion burner as claimed in claim 4, wherein the leading ends of
both the outer tube and inner tube terminate in the form of nozzles at the same vertical axis
but spaced apart such that there is an annular space between the inner wall of the outer
nozzle and the outer wall of the inner nozzle.
6. An improved fuel oil gasificaion burner as claimed in claim 5, wherein the tip of the nozzles of
the inner tube and that of the outer tube are circular in shape and configuration.
7 An improved fuel oil gasificaion burner as claimed in claim 6, wherein the inner tube is a tong unitary piece having substantively a cylindrical cross section and a minor convergent nozzle section.
8. An improved fuel oil gasificaion burner as claimed in claim 7, wherein the outer tube has a relatively longer cylindrical cross section and a shorter convergent nozzle section.
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9. An improved fuel oil gasification burner as claimed in claims 6 to 8,
wherein the different sections of the outer tube and the inner tube are
such that, when assembled, not only the convergent nozzle section but
also a portion of the trailing cylindrical cross section of the inner tube lies
within the convergent nozzle section of the outer tube.
10. An improved fuel oil gasification burner as claimed In claim 9 wherein the
expansion zone is formed of a gradually expanding tube, having the above
said two nozzle tips extending into a portion of its upstream end while its
downstream end terminates into an expansion chamber of a refractory
burner block.
11. An improved fuel oil gasification burner as claimed in claim 10 wherein the
said fuel supply pipe has its one end connected to the end downstream
region of the expansion chamber of the said refractory burner block. While
the other end of the fuel oil supply pipe is connected to the upstream
region of the said expansion tubes, preferably in an axis vertical to the
horizontal axis of the expansion tube.
12. An improved fuel oil gasification burner as claimed in claim 11, wherein
the number(s) of fuel oil supply tubes, also called return tube(s) varies
from 1 to 6 tubes depending on capacity and requirement.
13. An improved fuel oil gasification burner as claimed in claims 1 to 12,
wherein the refractory burner block is made of high-alumina material.
14. An improved method for the gasification of fuel oil which comprises
feeding a stream of gaseous fuel and combustion air, lighting up the
gaseous fuel, thereby creating suction of re-circulating the products of
combustion after passing through an expansion zone, injecting fuel oil into
the re-circulating stream carrying the products of combustion, allowing the
fuel oil to gasify and thereby to bum thereafter and terminating supply of
the fuel gas and continuing burning the fuel oil in the presence of
combustion air.
15. An improved method as claimed in claim 14, wherein the combustion air
and fuel gas are injected through nozzle means at oufficlgint pressure to
drag the fuel oil into an expansion zone.
16. An improved fuel oil gasification burner substantially as herein described
with reference to Figure 2 to 3 of the accompanying drawings.
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17 An improved method for the gasification of fuel oil substantially as herein described with reference to figures 2 and 3 of the accompanying drawings.
There is proposed an improvement fuel oil gasification burner, comprising a pair of co-axial tubes (1/2) of which the outer tubes (2) is adapted to feed combustion air and the inner tube (1) is adapted to feed fuel gas, the tips of the inner and outer tube terminating into an expansion zone, the region immediately next to the termination point of the tips of the said co-axial tubes being provided with a fuel-oil supply pipe (7) for feeding liquid fuel, said fuel supply pipe (7) having a trailing end connected down stream with the said expansion zone and a leading end terminating close to the tips of the co-axial tubes and there being provided a fuel oil inlet between said trailing end and leading end of the fuel supply pipe and a method of the gasification of fuel oil.