GASIFICATION BURNER
A gasification burner for combustion of a fuel, comprises a barrel having a front and a back, wherein exhaust gas produced by combustion exits at an outlet, a first air inlet into the barrel and a fuel inlet into the barrel, each positioned adjacent the back, wherein air at a first flow rate and fuel at a fuel flow rate are deliverable at the first air inlet and the fuel inlet, respectively, and a secondary air link operatively connected a second air inlet. The second air inlet is positioned closer to the front of the barrel than the first air inlet, and air at a second flow rate is deliverable at the second air inlet from the secondary air link and into the combustion chamber. A slag trap is operatively connected to the barrel so as to be able to receive slag generated from combustion of the fuel in the barrel, and the slag trap is closer to the back than the second air inlet. The second air inlet is offset with respect to the front from the secondary air link.
This invention relates to burner technology, and more particularly to a gasification burner.
BACKGROUND OF THE INVENTIONCyclone burners or furnaces were first developed back in the 1940s by Babcock and Wilcox. Generally, such furnaces are designed to burn coal as a fuel. The coal used is ordinarily a high rank coal with low water content. The coal and air are introduced at a back of a cyclone barrel and ignited. The air and fuel mixture can be introduced tangentially, or axially. Typically a secondary air source is also introduced all along the barrel to help increase combustion. Air swirls in a circular pattern around a primary axis of the barrel, enhancing combustion. Such known cyclone furnaces operate at relatively high temperatures (in excess of 1600° C.).
Not all of coal is comprised of hydrocarbons. Coal also contains materials which are non-combustible at the temperatures of operation of such cyclone furnaces. Typically such materials are referred to as ash or slag and include metal oxides, silicon or calcium oxides and various metals. Depending on the type of fuel burned these non-combustible materials may form slag or fly-ash or both. Slag is generally liquid at the temperatures associated with combustion of coal, and steps must be taken to collect and remove slag from the burner. Fly ash comprises the fine particles that rise with the flue/exhaust gases. Fly ash may include not only non-combustible components of the fuel, but may also include larger combustible particles which did not reside in the cyclone burner for sufficient time to be completely burned. Although fly ash can be collected by electrostatic precipitators, in instances where the exhaust gases are intended to be used as a heat source, fly ash may be undesirable. This is because as the fly ash is carried along with the exhaust gas and reaches a main boiler or any other heat transfer surface, the hot fly ash will tend to deposit on any cooler surface. As a result, efficiency of any heat transfer process will be reduced until the deposited fly ash is removed.
The Babcock and Wilcox furnace uses coal that produces a sticky fly ash upon combustion. Further, the sticky nature of the fly ash causes it to adhere to the walls of the interior. This provides a sticky surface onto which the coal particles also attach to the inner wall. Superheated air then passes over the stationary coal particles, allowing combustion to take place. This type of construction is relatively expensive, as water lines are provided to cool the walls and steps have to be taken to remove the accumulating fly ash.
The type of fuel used matters in the creation of slag and fly-ash. If the fuel is coal with an ash fusion temperature at a certain temperature, and the cyclone burner is run at a temperature above that ash fusion temperature, ash from the coal tends to become slag during combustion. If the burner is run at a temperature below the ash fusion temperature, ash from the coal tends to form fly-ash. It would therefore be desirable to provide a burner of improved construction with enhanced ability to burn fuel towards complete combustion (i.e., a gasification burner) without need to adhere particles to the wall of the burner, as well as to provide a burner which controls amounts of fly ash and slag produced.
SUMMARY OF THE INVENTIONIn accordance with a first aspect, a gasification burner for combustion of a fuel, comprises a barrel having a front and a back, wherein hot exhaust gas produced by combustion exits at an outlet, a first air inlet into the barrel and a fuel inlet into the barrel, each positioned adjacent the back, wherein air at a first flow rate and fuel at a fuel flow rate are deliverable at the first air inlet and the fuel inlet, respectively, and a secondary air link operatively connected to a second air inlet. The second air inlet is positioned closer to the front of the barrel than the first air inlet, and air at a second flow rate is deliverable at the second air inlet from the secondary air link and into the combustion chamber. A slag trap is operatively connected to the barrel so as to be able to receive slag generated from combustion of the fuel in the barrel, and the slag trap is closer to the back than the second air inlet. The second air inlet is offset with respect to the front from the secondary air link.
From the foregoing disclosure and the following more detailed description of various embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of cyclone burners. Particularly significant in this regard is the potential the invention affords for providing a burner which enhances combustion of fuel, and enhances slag removal. Additional features and advantages of various embodiments will be better understood in view of the detailed description provided below.
It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the gasification burner as disclosed here, including, for example, the specific dimensions of the air inlets will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to help provide clear understanding. In particular, thin features may be thickened, for example, for clarity of illustration. All references to direction and position, unless otherwise indicated, refer to the orientation illustrated in the drawings.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTSIt will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the burner disclosed here. The following detailed discussion of various alternate features and embodiments will illustrate the general principles of the invention with reference to a gasification burner suitable for use as a heat source. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.
Turning now to the drawings,
Optionally a controller 80 may be provided. The controller may be operatively connected to an ignition port or inlet 90, the first air inlet 44, the fuel inlet 40 and the second air inlet 50 so as regulate the combustion process. Primary air at the first air inlet can have a first flow rate, fuel at the fuel inlet 40 can have a fuel flow rate, and secondary air at the second air inlet can have a second flow rate. The controller can control each of these rates, either together or in isolation, and can be configured to maintain a pressure gradient between the first flow rate and the second flow rate such that air from the second inlet flows toward the first air inlet. The controller may also be configured to regulate the air flow rates and fuel flow rate such that a maximum temperature of combustion in the barrel occurs between the first air inlet and the second air inlet, most preferably generally adjacent the slag trap 20. Alternatively, the controller may be configured such that the first flow rate, second flow rate and fuel flow rate result in larger, incompletely combusted particles of fuel exiting the snout at the front of the barrel. Sensors (not shown) may be positioned at various locations on and in the burner to monitor combustion and provide feedback to the controller. The controller 80 may also include one or more display screens presenting information about the combustion process, such as, for example, combustion temperatures, so an operator can manually adjust or control flow rates, ignition, etc.
At the back of the burner, where the heavier particles tend congregate, there is a relatively low amount of oxygen. Preheated secondary air enters at or near the front of the burner, preferably in a circumferential direction essentially the same as the primary air. Advantageously, the secondary air is denser than air in the burner, including the exhaust gases. This difference in density can be due to the fact that the secondary air is cooler than the primary air. Thus, the heavier secondary air is flung toward the outer circumference of the barrel, as shown by the right side arrow in
Gasification burners as disclosed herein may also be used to burn high ash fusion temperature coals as part of a pulverized coal fired boiler. With certain types of coal it may be desirable to have some of the larger combustible particles of the coal fuel with low volatile matter exit the snout without completely combusting. Such larger particles are devolatilised and can be used for applications requiring low volatile matter, high fixed carbon content coal. Further, the hot exhaust air may be used as a source of heat for other operations, such as drying and setting low rank coals. In that environment, generally it is desirable to have as little fly ash as possible. The gasification burners disclosed here advantageously accomplish this, while also allowing for the option of use in production of low volatile matter, high fixed carbon content coal for use in applications requiring such coal.
In accordance with a highly advantageous feature, the secondary air link 260 is moved from generally close to the front 15 and to the second air inlet 250 into the combustion chamber to generally close to the back 13. That is, the secondary air port is closer to the back than the slag trap 20. Both the first air inlet 234 and the second air inlet 250 are positioned on a circumference of the barrel 212. The second air inlet 250 can be formed as an opening in the innermost layer 256 operatively connected to the air travel path 177. The secondary air source is designed to slow and control combustion of fuel as in the first embodiment, and may be introduced to the combustion chamber 117 at the second air inlet 250, which is in a position similar to the second air inlet 50 of the first embodiment.
For spacing considerations the primary air link 230 (shown in
A series of layers of materials may be used in the circumference of the barrel in accordance with this embodiment. The series of layers is useful to provide transition between the hot, abrasive combustion chamber and the ambient environment. An innermost layer 256 shown in
The air travel path 177 operatively connects the secondary air link 260 to the second air inlet 250 between the innermost layer 256 and the jacket 288. In the embodiment of
The ceramic paper and ceramic blanket can comprise alumino-silicate ceramic fiber based non-woven fabric materials. Typical properties are: 47% Al2O3; total Al2O3 and SiO2>97%; total Fe2O3: <1.0%; density: 10 lb/ft3; tensile strength: 25 PSI; loss of ignition (LOI): <9%; working temperature: 1,800° F. for continuous use; and 2300° F. maximum. Other combinations of heat resistant and insulating materials which define the air travel path and are suitable for use in gasification burners will be readily apparent to those skilled in the art given the benefit of this disclosure.
As higher temperatures may be experienced at the access port 267, slag trap 20 and snout 25, a second innermost layer 286 with the ability to withstand such higher temperatures may optionally be provided. In the embodiment of
The ceramic material may be extended to other locations as required. The ceramic material of the second innermost layer 286 may be the same or different than the innermost layer 256. Both innermost layers 256, 286 are positioned at the interior of the barrel and cooperate to define most of the combustion chamber. The material selected for use in the innermost layers depends upon the temperature inside the barrel and the chemical nature of the organic material used.
The output of the gasification burner is a function of the first air flow rate, the second air flow rate, and the fuel flow rate, as well as the ash fusion temperature of the fuel used. If the temperature inside the combustion chamber is higher than the ash fusion temperature of the coal, then little fly ash exits the snout. On the other hand, if the temperature inside the combustion chamber is lower than the ash fusion temperature of the coal, then fly ash will be formed which exits the outlet 55 of the gasification burner. In accordance with a highly advantageous feature, a controller of the gasification burners disclosed herein can control the settings of any or all of the first air flow rate, second air flow rate, and fuel flow rate, so that the output can be adjusted to produce either result.
In the embodiment shown in
In the embodiment of
The secondary air link is brings air from outside of the barrel to the second air inlet 550 which connects to the combustion chamber. The secondary air link is operatively connected to the second air inlet 550 via an air travel path 577 (shown in
Positioned within the combustion chamber 517 of this embodiment is an insert 524. The insert may be positioned adjacent or above the second air inlet, and generally near the front/top. As shown in
Additional measures may be taken to ensure that the amount of fly ash exiting the burner is reduced. A tube 526 may be positioned on the side of the insert 524 opposite the combustion chamber, at the front/top. The opening of the insert is operatively connected to the tube 526, which in turn is operatively connected to a snout 525. Instead of having the outlet positioned on the top and coaxial with the primary axis, in this embodiment the outlet is at the snout 525 which is positioned on a circumference of the barrel adjacent the front 15. By adjacent the front it is understood to mean that the outlet is closer to the front than the second air inlet, as shown in
The slag trap 520 is at the back when the outlet is at the circumference of the barrel. As shown in
From the foregoing disclosure and detailed description of certain embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to use the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
Claims
1. A gasification burner for combustion of a fuel, comprising, in combination:
- a barrel defining a combustion chamber and having a front and a back, wherein exhaust gas produced by combustion exits at an outlet;
- a first air inlet into the barrel and a fuel inlet into the barrel, each positioned adjacent the back, wherein air at a first flow rate and fuel at a fuel flow rate are deliverable at the first air inlet and the fuel inlet, respectively;
- a secondary air link operatively connected to a second air inlet, wherein the second air inlet is positioned closer to the front of the barrel than the first air inlet, and air at a second flow rate is deliverable at the second air inlet from the secondary air link and into the combustion chamber;
- a slag trap operatively connected to the barrel so as to be able to receive slag generated from combustion of the fuel in the barrel, wherein the slag trap is closer to the back than the second air inlet; and
- the second air inlet is offset with respect to the front from the secondary air link.
2. The gasification burner of claim 1 further comprising a jacket surrounding a part of the barrel, wherein air travels along the jacket from the secondary air link to the second air inlet and into the combustion chamber defined by the barrel.
3. The gasification burner of claim 2 wherein the secondary air link is positioned between the slag trap and the front of the barrel.
4. The gasification burner of claim 1 wherein the barrel defines a primary axis extending from the front to the back.
5. The gasification burner of claim 4 wherein the first air link is merged with the fuel inlet at the first air inlet into the barrel.
6. The gasification burner of claim 5 wherein air and fuel are introduced to the barrel in a direction tangential to the primary axis.
7. The gasification burner of claim 4 wherein air is directed into the barrel at the second air inlet in a direction tangential to the primary axis of the barrel.
8. The gasification burner of claim 4 wherein the barrel has a secondary axis perpendicular to the primary axis, and the second air inlet is aligned at an acute angle with respect to the secondary axis such that air is directed into the barrel at the second air inlet towards the back.
9. The gasification burner of claim 8 wherein the acute angle is 4-10 degrees.
10. The gasification burner of claim 1 wherein the first flow rate, second flow rate and fuel flow rate can be varied to generate a maximum temperature of combustion in the barrel adjacent the slag trap.
11. The gasification burner of claim 1 wherein the first flow rate, second flow rate and fuel flow rate can be varied to have incompletely combusted particles of fuel exit a snout at the front of the barrel.
12. The gasification burner of claim 1 wherein the fuel is coal having a particle size of less than 20 Mesh.
13. The gasification burner of claim 12 wherein the coal has a particle size of 100 Mesh to 20 Mesh.
14. The gasification burner of claim 1 wherein the barrel has a barrel width, a snout extends from the barrel at the front, and the snout has an outlet width less than the barrel width.
15. The gasification burner of claim 1 wherein the slag trap is closer to the front than the first air inlet.
16. The gasification burner of claim 1 further comprising a controller which controls the first flow rate, second flow rate and fuel flow rate.
17. The gasification burner of claim 16 wherein the controller is configured to regulate the air flow rates and fuel flow rate such that a maximum temperature of combustion in the barrel occurs between the first air inlet and the second air inlet.
18. The gasification burner of claim 1 wherein the barrel has a length and the slag trap is positioned 45-85 percent of the length of the barrel from the back.
19. The gasification burner of claim 2 wherein the barrel comprises an innermost layer and an air travel path operatively connects the secondary air link to the second air inlet between the innermost layer and the jacket.
20. The gasification burner of claim 19 wherein the barrel further comprises an insulating layer positioned between the jacket and the air travel path.
21. The gasification burner of claim 20 further comprising an additional layer attached to the innermost layer.
22. The gasification burner of claim 20 wherein the jacket comprises an alloy steel, and the innermost layer comprises one of an insulating ceramic and a metal alloy coated with a thermal barrier coating.
23. The gasification burner of claim 20 wherein the barrel further comprises a second innermost material, wherein each of the innermost layers cooperate to define the combustion chamber.
24. The gasification burner of claim 1 wherein an outlet at the front is operatively connected to at least one of a drying device, an upgrading device, and a combustion device.
25. The gasification burner of claim 1 wherein an outlet at the front is operatively connected to a turbine, and the turbine is adapted to generate electricity using heat from the exhaust gas.
26. The gasification burner of claim 25 wherein the outlet is operatively connected to a heat transfer device, and the heat transfer device is adapted to transfer heat from the exhaust gas to ambient air to produce heated ambient air, and the turbine is adapted to receive the heated ambient air.
27. The gasification burner of claim 25 wherein the outlet is operatively connected to a heat transfer device adapted to transfer heat from the exhaust gas to water from a boiler to produce steam, and the steam drives the turbine.
28. The gasification burner of claim 25 further comprising a second gasification burner positioned between the outlet and the turbine.
29. The gasification burner of claim 1 wherein the outlet is at one of the front and a circumference of the barrel adjacent the front.
30. The gasification burner of claim 29 wherein the slag trap is at the back when the outlet is at the circumference of the barrel.
31. The gasification burner of claim 1 wherein the second air inlet is positioned between the front and the secondary air link.
32. The gasification burner of claim 2 wherein the secondary air link is connected to the second air inlet by an air travel path, the barrel has a length, and the air travel path is at least 50% of the length of the barrel.
33. The gasification burner of claim 1 wherein the barrel has a combustion chamber diameter, the outlet is at a snout having an outlet diameter which is less than the combustion chamber diameter, and the snout is positioned outside the combustion chamber.
34. The gasification burner of claim 33, further comprising a tertiary air link operatively connected to the snout at a tertiary air inlet and adapted to introduce tertiary air into the snout.
35. The gasification burner of claim 1 further comprising an insert into the combustion chamber positioned adjacent the second air inlet, wherein the insert has an opening operatively connecting the combustion chamber to the outlet which has a diameter less than a diameter of the combustion chamber.
36. The gasification burner of claim 1 further comprising:
- a second gasification burner having a second combustion chamber; and
- an exhaust channel operatively connecting the outlet of the gasification burner to the second combustion chamber of the second gasification burner.
37. The gasification burner of claim 1 wherein the outlet is at a snout, and a nozzle is positioned in the snout which defines a restrictive opening remote from the outlet which is smaller than the outlet.
Type: Application
Filed: Apr 5, 2012
Publication Date: Apr 25, 2013
Applicant: PT TOTAL SINERGY INTERNATIONAL (Jakarta Pusat)
Inventor: IR. Harsudi Supandi (Kelapa Gading Timur)
Application Number: 13/807,341
International Classification: F23D 99/00 (20100101);