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Title:
APPARATUS FOR BURNING BIOMASS WASTES
Document Type and Number:
WIPO Patent Application WO/2012/169870
Kind Code:
A1
Abstract:
The present invention relates to apparatus for burning biomass wastes, and more particularly to a two-stage gasifier burner for burning biomass wastes which contain relatively high moisture content including municipal solid wastes (MSW). The two- stage gasifier burner (100) having an upper combustion chamber (120) and a lower combustion chamber (140). The lower combustion chamber includes: (a) at lease one grate array arrangement structure (150); (b) at least one fuel feed inlet (160); (c) at least one enclosure (180) with pivotally pendular drive; and d) at least one ash removal device (170) disposed at an interior burner (142); wherein at least half V-configuration grate support structure (152) is provided such that at least one grate array arrangement structure (150) is located adjacent to the at least one ash removal device (170) and is supported by the at least half V-configuration grate support structure (152).

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Inventors:
TK PILLAY PANJALINGAM (MY)
D LEFCORT MALCOLM (MY)
Application Number:
MY2011/000084
Publication Date:
December 13, 2012
Filing Date:
June 07, 2011
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
TK PILLAY PANJALINGAM (MY)
D LEFCORT MALCOLM (MY)
International Classes:
F23G5/16; F23G5/32; F23G7/10; F23H7/08; F23H11/24
Foreign References:
US20030196577A12003-10-23
US20090151609A12009-06-18
US4747355A1988-05-31
Other References:
None
Attorney, Agent or Firm:
NANJAPPAN, Puvaneswari (Suite 8-7-2 Menara Mutiara Bangsar,Jalan Liku Off Jalan Riong,Bangsar, Kuala Lumpur, MY)
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Claims:
CLAIMS

1. A two-stage gasifier burner (100) for burning biomass wastes which contain relatively high moisture content, having an upper combustion chamber (120) and a lower combustion chamber (140) characterized in the, the lower combustion chamber (140) includes:

(a) at least one grate array arrangement structure (150);

(b) at least one fuel feed inlet (160);

(c) at least one enclosure (180) with pivotally pendular drive; and

(d) at least one ash removal device (170) disposed at an interior burner (142); wherein at least half V-configuration grate support structure (152) is provided such that at least one grate array arrangement structure (150) is located adjacent to the at least one ash removal device (170) and is supported by the at least half V- configuration grate support structure (152).

2. A two-stage gasifier burner (100) according to Claim 1 , wherein the fuel feed inlet (160) is located above one side of underlying grate array arrangement structure (150). 3. A two-stage gasifier burner (100) according to Claim 1 , wherein the fuel feed inlet (160) is provided with a hopper (162) to direct fuel materials or wastes into the interior burner (142) through an opening (164).

4. A two-stage gasifier burner (100) according to Claim 3, wherein the fuel feed inlet (160) uses airlock system (130) to control flow of the fuel materials or wastes into the interior burner (142) and to prevent hot producer gas and ash from leaving the burner and escaping through the opening (164) of the fuel feed inlet (160) to the hopper (162) or any air ingress.

A two-stage gasifier burner (100) according to Claims 3 and 4, wherein the fuel materials or wastes are biomass wastes, empty fruit bunches (EFB) or any other wastes which contain relatively high moisture content including municipal solid wastes (MSW).

6. A two-stage gasifier burner (100) according to Claim 1 , wherein the grate array arrangement structure (150) composed of multiple individual grate boxes (154).

7. A two-stage gasifier burner (100) according to Claim 6, wherein the multiple individual grate boxes (154) are supported by the at least half V-configuration grate support structure (152).

8. A two-stage gasifier burner (100) according to Claim 7, wherein each individual grate box (154) includes multiple grate support plates (156).

9. A two-stage gasifier burner (100) according to Claim 8, wherein the grate support plates (156) which are closest to the fuel feed inlet (160) are affixed at greatest height.

10. A two-stage gasifier burner (100) according to Claim 9, wherein the height of the grate support plates (156) progressive increases with distance outward from the fuel feed inlet (160) toward the ash removal device (170), forming an irregular stair step-like arrangement.

11. A two-stage gasifier burner (100) according to Claims 1 and 10, wherein the pivotally pendular drive is slidably pivotally connected to each grate support plates (156) such that to induce forward and rearward motions swinging motion to the grate support plates (156).

12. A two-stage gasifier burner (100) according to Claims 11 , wherein the pivotally pendular drive drives frontward and rearward sliding reciprocation of ash plates (158) to displace and direct the ash toward the ash removal device (170). 13. A two-stage gasifier burner (100) according to Claim 1 , wherein the ash removal device (170) includes an ash auger (172) disposed at an ash collection trough (174) and enclosed by enclosure wall (176).

14. A two-stage gasifier burner (100) according to Claim 13, wherein the ash auger (172) is a single or double helical screw associated with rotary motor.

15. A two-stage gasifier burner (100) according to Claim 13, wherein the ash collection trough (174) and enclosure wall (176) are installed in front of the lowest grate box (154) and span the entire width of the grate array arrangement structure (150).

16. A two-stage gasifier burner (100) according to Claim 1 , wherein the two-stage gasifier burner (100) further provided with a secondary combustion burner (200) for use in a biomass fired cogeneration plant. 17. A two-stage gasifier burner (100) according to Claim 16, wherein the secondary combustion burner (200) is a cyclone combustor (210) having a central collector compartment (220) and a cone collector compartment (230).

18. A two-stage gasifier burner (100) according to Claim 17, wherein the cyclone combustor (210) is in fluid communication with the upper combustion chamber (120) of the two-stage gasifier burner (100) through interconnected pipes or ducts with a diverter gate (222).

19. A two-stage gasifier burner (100) according to Claim 18, wherein the upper combustion chamber (120) is further provided with a dump stack (122) for any emergency flare. 20. A two-stage gasifier burner (100) according to Claim 18, wherein produced gas made by the lower combustion chamber (140) of the two-stage gasifier burner (100) is mixed with over-fire air (124) at the upper combustion chamber (120) prior to entering the cyclone combustor (210) of the secondary combustion burner (200) in a tangential manner.

21. A two-stage gasifier burner (100) according to Claim 20, wherein gasifier exhaust gas from the cyclone combustor (210) is suitable for directly firing into other processes, such as for example, to heat recovery steam generator (HRSG) without any complex hot gas clean up systems via an output choke (250) disposed at the top of the cyclone combustor (210).

22. A two-stage gasifier burner (100) according to Claim 17, wherein the cyclone combustor (210) produces a strong swirling flow with good mixing of additional air (224) for complete vortex combustion and creating stable combustion conditions in the central collector compartment (220).

23. A two-stage gasifier burner (100) according to Claim 17, wherein the cone collector compartment (230) is an ash separator to further remove particles by vortex swirling flow so as enables other particulates being flung to the bottom and to be removed through an air lock (260) disposed at the bottom of the cone collector compartment (230).

Description:
APPARATUS FOR BURNING BIO ASS WASTES

FIELD OF INVENTION This invention relates to apparatus for burning biomass wastes, and more particularly to a two-stage gasifier burner for burning biomass wastes including municipal solid wastes (MSW).

BACKGROUND OF INVENTION

Wet materials or biomass wastes must be dried to certain extent prior to combustion. In many incinerators, such as rotary kiln, wastes are passed through the length of the incinerator while undergoing incineration. If the wastes contain significant amount of moisture, burden will be placed on combustion process. As thermal disposal of industrial, agricultural or other type of wastes represents one of the most important environmentally friendly processes, numerous efforts have been made to a sustainable combustion apparatus for elimination of problematic waste materials.

Various two-stage gasifier burners which are capable of combusting wet waste materials have been introduced in the art. However, many of them addressed problems and inefficiencies inherent in prior gasifier burners such as, for example, gaseous combustion problems, particulate removal from gaseous effluent, inefficient fuel supply and inefficiency in ash removal system in reducing harmful emissions. To reduce harmful emissions to the environment, there must be complete degradation of the pollutants and ensuring combustion of residues into reusable and inert matters. In order to achieve the abovementioned, the combustion of the waste materials should be uniform and homogeneous. Wastes are usually subjected to pre-treatment such as pressing, shredding, chipping and any other processes prior to combustion. In the combustion of solid waste materials, it is desirable to be presented in a form of homogeneous and to be comminuted in smaller sizes so as to provide larger surface areas for gaseous contact during combustion. However, some pre-treatment processes may not be able to achieve the desired results while additional capitals and operating costs have been supplemented to the combustion process. Many two-stage gasifier burners allow combustion of high moisture containing wastes in their combustion chamber. However, similar to other combustion processes, the wastes are subjected to pre-treatment prior to combustion. Many prior art gasifier burners suffer from inefficiencies in operations due to large parts of inefficient and impractical fuel supply and ash removal. Such inefficiencies particularly in material handling which tends to cause less efficient gasification of fuel due to uneven distribution of wet wastes onto the grate surfaces. This caused potentially lengthy and frequent shutdowns for maintenance, such as to remove clogging of waste in fuel feed system, as well as to remove ash and residues from ash collection and removal devices. Moreover, wastes such as sewage sludge with substantial high moisture content level tends to become cohesive, requiring unacceptable high consumption of energy for conveyance and drying.

In view of these and other shortcomings of the prior art there is a need in the art for an improved apparatus for combusting biomass wastes with relatively high moisture content, including municipal solid wastes (MSW). Accordingly, the present invention provides an improved two-stage gasifier burner which permits uniform and homogeneous combustion by providing an effective material handling system for optimum operation processes. Moreover, the two-stage gasifier burner of the present invention enables to substantially reduce clogs of waste materials. In addition, the present invention further provides an efficient ash and residues removal device which is cost effective and yet easy to maintain.

SUMMARY OF INVENTION

Accordingly, the present invention relates to an apparatus for burning biomass wastes and more particularly, to a two-stage gasifier burner for burning biomass wastes which contain relatively high moisture content including municipal solid wastes (MSW). The two-stage gasifier burner having an upper combustion chamber and a lower combustion chamber characterized in that the lower combustion chamber includes: (a) at least one grate array arrangement structure; (b) at least one fuel feed inlet; (c) at least one enclosure with pivotally pendular drive; and (d) at least one ash removal device disposed at an interior burner; wherein at least half V-configuration grate support structure is provided such that at least one grate array arrangement structure is located adjacent to the at least one ash removal device and is supported by the at least half V-configuration grate support structure.

In the preferred embodiment, the fuel feed inlet is located above one side of underlying grate array arrangement structure. Accordingly, the fuel feed inlet is provided with a hopper to direct fuel materials or wastes into the interior burner through an opening. It is to be noted that the fuel feed inlet uses airlock system to control flow of the fuel materials or wastes into the interior burner and to prevent hot producer gas and ash from leaving the burner and escaping through the opening of the fuel feed inlet to the hopper or any air ingress.

Accordingly, the fuel materials or wastes are biomass wastes, empty fruit bunches or any other wastes which consist of relatively high moisture content, including municipal solid wastes (MSW).

Accordingly, the grate array arrangement structure composed of multiple individual grate boxes. Said multiple individual grate boxes are symmetrically arranged and are supported by the at least half V-configuration grate support structure. Each individual grate box includes multiple grate support plates. Accordingly, the grate support plates which are closest to the fuel feed inlet are affixed at greatest height. The height of the grate support plates progressive increases with distance outward from the fuel feed inlet toward the ash removal device, forming an irregular stair step-like arrangement.

In the preferred embodiment, the pivotally pendular drive is slidably pivotally connected to each grate support plates such that to induce forward and rearward motions swinging motion to the grate support plates. Accordingly, the pivotally pendular drive drives frontward and rearward sliding reciprocation of ash plates to displace and direct the ash toward the ash removal device.

The ash removal device of present invention includes an ash auger disposed at an ash collection trough and enclosed by enclosure wall. Preferably, the ash auger is a single or double helical screw associated with rotary motor. The ash collection trough and enclosure wall are installed in front of the lowest grate box and span the entire width of the grate array arrangement structure. It will be appreciated that accumulated ash that is swept off the lowest grate support plate and into the ash collection trough by the action of reciprocating of the grate support plates, then falls through openings at the enclosure wall.

In another preferred embodiment, the interior burner can be divided into two symmetrical halves by the ash removal device located at the middle of a V- configuration grate support structure such that two substantial identical grate arrays arrangement structure are oppositely located one on either side of the ash removal device and are supported by the V-configuration grate support structure. The fuel feed inlets are then symmetrically provided on both sides of the lower combustion chamber and are located one above either side of underlying grate arrays arrangement structure

If desired, the two-stage gasifier burner further provided with a secondary combustion burner for use in a biomass fired cogeneration plant. In another preferred embodiment of the present invention, the secondary combustion burner is a cyclone combustor having a central collector compartment and a cone collector compartment.

Accordingly, the cyclone combustor is in fluid communication with the upper combustion chamber of the two-stage gasifier burner through interconnected pipes or ducts with a diverter gate. Preferably, the upper combustion chamber is further provided with a dump stack for any emergency flare.

It will be appreciated that produced gas made by the lower combustion chamber of the two-stage gasifier burner is mixed with over-fire air at the upper combustion chamber prior to entering the cyclone combustor of the secondary combustion burner in a tangential manner. Gasifier exhaust gas from the cyclone combustor is suitable for directly firing into other processes, such as for example, to heat recovery steam generator (HRSG) without any complex hot gas clean up systems via an output choke disposed at the top of the cyclone combustor.

In the preferred embodiment, the cyclone combustor produces a strong swirling flow with good mixing of additional air for complete vortex combustion and creating stable combustion conditions in the central collector compartment. Accordingly, the cone collector compartment of the cyclone combustor is an ash separator to further remove particles by vortex swirling flow so as enables other particulates being flung to the bottom and to be removed through an air lock disposed at the bottom of the cone collector compartment.

The present invention consists of several novel features and a combination of parts hereinafter fully described and illustrated in the accompanying description and drawings, it being understood that various changes in the details may be made without departing from the scope of the invention or sacrificing any of the advantages of the present invention.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a partially sectional diagrammatic view of a two-stage gasifier burner in accordance with preferred embodiment of present invention;

FIG. 2 is a partially sectional front view of FIG. 1 according to the preferred embodiment of the present invention; FIG. 3 is a schematic diagram of structure and arrangement of the two-stage gasifier burner and a cyclone combustor in accordance with preferred embodiment of present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention relates to an apparatus for burning biomass wastes and more particularly, to a two-stage gasifier burner for burning biomass wastes which contain relatively high moisture content, including municipal solid wastes (MSW). Hereinafter, this specification will describe the present invention according to the preferred embodiment of the present invention. However, it is to be understood that limiting the description to the preferred embodiment of the invention is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the scope of the appended claims.

The present invention provides an improved two-stage gasifier burner which permits a uniform and homogeneous combustion, and it operates in a cost-effective manner and substantially reducing clogs during feeding and removal processes. Accordingly, the improvements have been made to secondary chamber of the two-stage gasifier burner, wherein an improved feeding device and grating arrangement device are provided thereof to enable effective material handling for uniform and homogeneous combustion. It will be appreciated that the improved feeding and grating arrangement devices also enable the optimization of combustion operational processes. Particularly, the feeding and grating arrangement devices are capable of substantially reduced clogs of waste materials during the feeding and removal processes. Said improved two-stage gasifier burner further provided with an efficient ash and residues removal device which is cost-effective and yet easy to maintain.

Accordingly, it is an object of present invention to provide an apparatus for combusting biomass wastes having an improved feeding and grating arrangement devices for uniformly and homogeneously combustion. It is another object of the present invention to provide a two-stage gasifier burner that operates in a cost-effective manner, and enables to substantially reduce clogs during feeding and removal processes. Accordingly, the present invention allows distribution of wastes uniformly and homogeneously on symmetrical V-grate array arrangement structure and provides efficient ash removal devices for centrally removal of ash and residues.

The improved two-stage gasifier burner (100) for burning biomass wastes which contain relatively high moisture content, including municipal solid wastes ( SVV) according to the preferred embodiment of the present invention will now be described in accordance to the accompanying drawings Figures 1 to 3, both individually and in any combination thereof.

In accordance with the preferred embodiment, the improved two-stage gasifier burner (100) generally includes an upper combustion chamber (120) and a lower combustion chamber (140). The upper combustion chamber (120) will not be described herein as it is known in the art. Though, the lower combustion chamber (140) of the preferred embodiment generally includes a grate array arrangement structure (150), fuel feed inlets (160) and ash removal device (170) which are disposed at center of an interior burner (142) of the lower chamber (120). Accordingly, the interior burner (142) is divided into two symmetrical halves by the ash removal device (170) disposed at the middle of a V-configuration grate support structure (152), such that two substantial identical grate arrays arrangement structure (150) are oppositely located one on either side of the ash removal device (170) and are supported by the V-configuration grate support structure (152).

It is to be noted that in a similar fashion, the fuel feed inlets (160) are symmetrically provided on both sides of the lower combustion chamber (140) and are located one above either side of underlying grate arrays arrangement structure (150) of the V- configuration grate support structure (152). Preferably, the fuel feed inlets (160) span the entire width of the interior burner (142) and supplies fuel materials or wastes such as biomass wastes, empty fruit bunches (EFB) or any other wastes which consists of relatively high moisture content, including municipal solid wastes (MSW) to the corresponding underlying grate arrays arrangement structure (150).

It is to be noted that the interior burner (142) of the lower combustion chamber (140) can also be configured to include only half portion of the V-configuration grate support structure (152), such that one grate array arrangement structure (150) is located adjacent to the ash removal device (170) and is supported by the half V-configuration grate support structure (152). Thus, only one fuel feed inlet (160) is required to be located above one side of underlying grate array arrangement structure (150).

In the preferred embodiment, the fuel feed inlet (160) is provided with a hopper (162) to direct the fuel materials or wastes into the interior burner (142) through an opening (164). Preferably, the fuel feed inlet (160) uses airlock system (130) to control the flow of the fuel materials or wastes into the interior burner (142). It is to be noted that the airlock system (130) also prevents hot producer gas and ash from leaving the interior burner (142) and escaping through the opening (164) of the fuel feed inlet (160) to the hopper (162) or any air ingress. The fuel materials or wastes transported by the hopper (162) tends to be discharged and fall onto surfaces of the underlying grate array arrangement structure (150) in a relatively uniform and homogeneous distribution over entire length of the opening (164), and hence over entire width of the corresponding grate array arrangement structure (150). Such uniform and homogeneous distribution of the fuel materials or wastes results in grater efficiency of gasification and overall combustion of the fuel materials or wastes. Moreover, the configuration of the fuel feed inlet (160) which is located one above either side of underlying grate arrays arrangement structure (150) enables to substantially reduce clogs during feeding process. In the preferred embodiment, the grate array arrangement structure (150) composed of multiple individual grate boxes (154) which are symmetrically arranged and located one on either side of the ash removal device (170), and are supported by the V- configuration grate support structure (152). Accordingly, each individual grate box (154) includes multiple grate support plates (156) installed at varying vertical heights. The grate support plates (156) which are closest to the fuel feed inlet (160) are affixed at greatest height, and the height of the grate support plates (156) are progressive increases with distance outward from the fuel feed inlet (160) toward the ash removal device (1 0), thus forming an irregular stair step-like arrangement as shown in FIG. 2. It will be appreciated that a pivotally pendular drive (not shown) is provided and supported by an enclosure (180). The pivotally pendular drive is slidably pivotally connected to each grate support plate (156) such that to induce forward and rearward motions swinging motion to each grate support plate (156). Thus, in turn drives the frontward and rearward sliding reciprocation of ash plates (158) to displace and direct the ash toward the ash removal device (170).

By way of example and not by way of limitation, the multiple individual grate boxes (154) are preferably stacked to approximate height of 1.8 m (approx. 6 ft) where the air is admitted from bottom. Thus, it allows longer residence time of burning. It will be appreciated that temperature at the grate array arrangement structure (150) is maintained at a range of 600 8 C to 700 8 C, such that volatile gasses in the biomass and water vapour of the fuel materials or wastes such as, for example EFB, to be volatilized during the combustion. It will be appreciated that gases and tars produced in the combustion will be moved up and raised above ignition temperature approximately above 760 9 C or higher in the upper combustion chamber (120). Prior to entering the secondary combustion chamber (200), the temperature of the gases will be raised up to, for example, approximately 800 8 C to 900 S C or higher with over-fire air (124). It will be appreciated that output gas from the secondary combustion chamber (200) will be controlled at average temperature of at least 1000 e C to 1010 B C. Said output gas will be then treated or further processed as deemed suitable.

It will be appreciated that the preferred embodiment of the present invention is intended for, but not restricted to, use in combusting EFB waste with high moisture content. For instance, with suitable adaptation, all other types of waste which has high moisture content including municipal solid wastes (MSW) and allows combustion without being subjected to pre-treatment can also be used instead of the EFB. In accordance with preferred embodiment, the ash removal device (170) includes an ash auger (172) disposed at an ash collection trough (174) and enclosed by enclosure wall (176). Preferably, the ash auger (172) can be of, but not limited to a conventional single or double helical screw associated with rotary motor (not specifically shown). The ash removal device (170) is desirably located at the centre of the interior burner (142). Particularly, the ash removal device (170) is desirably located at middle of V- configuration grate support structures (152) such that two substantial identical grate arrays arrangement structures (150) are located one on either side of the ash removal device (170) and are supported by the V-configuration grate support structures (152).

Should the interior burner (142) of the lower combustion chamber (140) is configured to include only half portion of the V-configuration grate support structure (152), the ash removal device (170) will then be located at one side of the interior burner (142), such that one grate array arrangement structure (150) is located adjacent to the ash removal device (170) and is supported by the half V-configuration grate support structure (152).

In the preferred embodiment, the ash collection trough (174) and enclosure wall (176) are installed adjacent to the lowest grate box (154) and are spanned the entire width of the grate array arrangement structure (150). It will be appreciated that accumulated ash which are swept off to the lowest grate support plate (156), and into the ash collection trough (174) are significantly by the action of reciprocating of the grate support plates (156), which are then fall through an opening (178) of the enclosure wall (176). The ash and residues are being collected by the ash collection trough (174) of the ash removal device (170) and are being centrally removed from the interior burner (142) to exterior through the ash auger (172). If desired, the present invention may further provide with a secondary combustion burner (200) for use in a biomass fired cogeneration plant. Accordingly, the secondary combustion burner (200) is used for further ash separation and heat generation. In accordance with another preferred embodiment of the present invention, said secondary combustion burner (200) is a cyclone combustor (210) which having a central collector compartment (220) and a cone collector compartment (230). Said cyclone combustor (210) is preferably used to maximise particle and ash separation from the output gas flow from the two-stage gasifier burner (100). Accordingly, the cyclone combustor (210) is in fluid communication with the upper combustion chamber (120) of the two-stage gasifier burner (100) through interconnected pipes or ducts with a diverter gate (222). The diverter gate (222) is usually open during normal operation. It will be appreciated that the upper combustion chamber (120) is further provided with a dump stack (122) for any emergency flare. The diverter gate (222) will be activated to direct flare to emergency dump stack (122).

By way of example and not as a limitation, temperature at the upper combustion chamber (120) of the two-stage gasifier burner (100) use for biomass fired cogeneration plant is preferably maintained at a range of 600 8 C to 700 8 C, such that volatile gasses in the biomass and water vapour of the fuel materials or wastes are volatilized during the combustion. Other gases and tars produced in the combustion will be raised above ignition temperature approximately above 760 8 C or higher in the upper combustion chamber (120). It will be appreciated that produced gas made by the lower combustion chamber (140) of the two-stage gasifier burner (100) is mixed with over-fire air (124) at the upper combustion chamber (120) prior to entering the cyclone combustor (210) of the secondary combustion burner (200) in a tangential manner, so that the ignition temperature entering into central collector compartment (220) of the cyclone combustor (210) may be reached up to, for example, approximately 800 2 C - 900 8 C or higher with additional air (224). It will be appreciated that the design of the cyclone combustor (210) of the secondary combustion burner (200) should be robust and suitable for firing with varying input conditions. It will be appreciated that gasifier exhaust gas from the cyclone combustor (210) is suitable for directly firing into other processes, such as for example, to heat recovery steam generator (HRSG) without any complex hot gas clean up systems via an output choke (250) disposed at the top of the cyclone combustor (210). The output gas from the cyclone combustor (210) is preferably controlled at average temperature of at least 1000 B C to 1010 8 C.

In the preferred embodiment, the cyclone combustor (210) produces a strong swirling flow with good mixing of additional air (224) for complete vortex combustion and creating stable combustion conditions in the central collector compartment (220). It will be appreciated that air under pressure is further induced into the central collector compartment (220) for hot gas clean up as well as to provide stable combustion conditions. The cone collector compartment (230) which serves as ash separator to further remove particles by vortex swirling flow so as enables other particulates being flung to the bottom and to be removed through an air lock (260) disposed at the bottom of the cone collector compartment (230).

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the principle and scope of the invention, and all such modifications as would obvious to one skilled in the art intended to be included within the scope of following claims.