Technical Field of the Present Invention

The present invention relates to an incinerator for turbulent combustion of fuel, such as coal or biomass fuel, with increased efficiency and low emission. Background of the Present Invention

A wide variety of combustion methods and incinerators are available in the prior art, such as stoker-type combustors, fluidized bed combustion, pulverized coal combustion and cyclone combustors. However, these systems have many issues.

One major issue is low efficiency. The cause for low efficiency can be twofold. First is the incomplete burning of the fuel, such as coal, due to build-up of slag around unburnt coal preventing its access to oxygen. For this reason, coal having higher calorific content, such as bituminous coal, which is harder to mine and more expensive than coal having lower calorific content, such as lignite, is preferred. Second is the incomplete oxidation of carbon monoxide to carbon dioxide, which both lowers the overall efficiency of the incinerator and causes emission of harmful carbon monoxide into the atmosphere.

Another issue is fly ash that is released to the atmosphere along with flue gas, which requires the use of scrubbers, electrostatic precipitators or other filtering devices in order to comply with air pollution standards. Strict emission standards also limit the amount of carbon monoxide, NO _x and SO _x , all of which are byproducts of coal combustion that is allowable to be released into the atmosphere. To comply with this, it is imperative that complete combustion be achieved.

The attempts made in the state of the art to alleviate these problems associated with incinerators are disclosed by European patent no. 2 402 651, US patent no. 4,007,697, US patent no. 4,633,790, US patent no. 4,430,948, US patent no. 5,588,378 and US patent no. 5,299,532, among others.

The present invention aims to improve on the problems described in the prior art. The invention makes use of two-stage double cyclone turbulent combustion in order to achieve improved efficiency and low emission values. Fuel feed enters the main combustion chamber from the top, and fall to the grate, from the openings of which oxygen enriched air is blown upwards. Burning fuel particles are suspended by turbulence to prevent slag build-up and maximize contact with oxygen enriched air to ensure complete combustion. The incinerator is suitable for burning solid fuels with lower calorific content, such as lignite, as well as biomass fuel, or a combination thereof. The present invention can be used in any application requiring heat transfer, such as industrial or domestic-type heating (boilers) and power generation.

The present invention provides an incinerator for turbulent combustion of fuel as provided by the characterizing features defined in Claim 1. Objects of the Present Invention

The object of the invention is to provide an incinerator for complete turbulent combustion of fuel with increased efficiency and low emission.

Brief Description of the Technical Drawings

Accompanying drawings are given solely for the purpose of exemplifying an incinerator, whose advantages over prior art were outlined above and will be explained in brief hereinafter.

The drawings are not meant to delimit the scope of protection as identified in the Claims, nor should they be referred to alone in an effort to interpret the scope identified in said Claims without recourse to the technical disclosure in the description of the present invention.

Figure 1 demonstrates a vertical sectional view of an embodiment of the present invention. Figure 2 demonstrates the two-stage double cyclone turbulent flow of gas during operation of the present invention as depicted in Figure 1.

Figure 3 demonstrates an enlarged view of the components of the main combustion chamber of the present invention as depicted in Figure 1.

Figure 4 demonstrates an enlarged view of the main combustion chamber during operation of the present invention as depicted in Figure 1. Figure 5 demonstrates a top view of the grate and the air inflow mechanism of the present invention as depicted in Figure 1.

Figure 6 demonstrates an enlarged view of the components of the secondary combustion chamber of the present invention as depicted in Figure 1.

Figure 7 demonstrates a vertical sectional view of an embodiment of the present invention. Figure 8 demonstrates a top view of the grate and the air inflow and feed mechanisms of an embodiment of the present invention as depicted in Figure 7.

Figure 9 demonstrates a vertical sectional view of another embodiment of the present invention.

Detailed Description of the Present Invention

The following numerals are referred to in the detailed description of the present invention:

10 Turbulent Combustion Incinerator

11 Main Combustion Chamber

12 Secondary Combustion Chamber

13 Insulating Ceramic Fiber Wool

14 Refractory Material

15 Fuel Hopper

16 Fuel Feeder Motor 17 Fuel Transfer Auger

18 Support Element

19 Ball Bearing

20 Fuel Feed Pipe

21 Fuel Feed Inlet

22 Heat Collecting Dome

23 Dome Opening

24 Rotatable Sweeper

25 Fuel Spreader

26 Slag Mill

27 Sweeper Motor

28 Grate

29 Grate Holes

30 Air Blower

31 Air Transport Pipe

32 Gas Acceleration Nozzle

33 Funnel Pipe Bend

34 Ash Collection Cone

35 Ash Transfer Auger

36 Counter-Weight Cover

37 Dome channels

Figure 1 illustrates an embodiment of the present invention, referred to as turbulent combustion incinerator (10). Turbulent combustion incinerator (10) consists of a two-stage double cyclone turbulent combustion system. The first stage takes place in the main combustion chamber (11), where solid or biomass fuel is burned. The second stage takes place in the secondary combustion chamber (12) where components of flue gas, such as CO are combusted completely. Inside surface of turbulent combustion incinerator (10) is of refractory material (14) and the outside is insulated by ceramic fiber wool (13) to prevent loss of heat. The present invention can be used in a variety of applications that require heat transfer, such as boilers and power generation. Harvest of heat energy from the turbulent combustion incinerator may occur via a jacket or pipes placed in the outside walls of the turbulent combustion incinerator where desired fluid can flow, or some other heat exchange method can be used.

Fuel, such as lignite or biomass, is fed into the system from above by fuel hopper (15). The fuel is transferred along the fuel hopper (15) by fuel transfer auger (17) driven by fuel feeder motor (16) and mechanically borne by ball bearing (19). Fuel hopper is attached to the main body of the turbulent combustion incinerator by support element (18). From the top, fuel is transferred directly to the main combustion chamber (11) via fuel feed pipe (20) and fuel feed inlet (21). Fuel feed inlet (21) is made of ceramic material resistant to temperatures above 1200°C and is preferably insulated from fuel feed pipe (20).

Main combustion chamber (11) and secondary combustion chamber (12) will be described in more detail hereinbelow. In brief, fuel entering the main combustion chamber (11) from above via fuel feed inlet (21) is met with air flowing from below via grate holes (29) of the grate (28). Air is supplied to the main combustion chamber (11) from air blower (30) via the air transport pipe (31). Fuel is evenly distributed across grate (28) by rotatable sweeper (24), rotated by sweeper motor (27) to ensure more efficient combustion. Bottom ash produced by combustion is collected by ash collection cone (34) and removed by ash transfer auger (35) with counter-weight cover (36) which disposes of bottom ash when a certain weight of ash is reached. Flue gas, fly ash and other volatiles resulting from combustion are passed through the dome openings (23) around the heat collecting dome (22) to the secondary combustion chamber (12), where the second stage combustion of CO, etc. occurs. Completely combusted flue gas is collected by gas acceleration nozzle (32) and released into the atmosphere, or transferred for further processing, such as scrubbing, filtering and/or electrostatic precipitation, via funnel pipe bend (33). Flow paths of gas inside turbulent combustion incinerator are described in Figure 2.

Figures 3, 4 and 5 illustrate main combustion chamber (11) in detail. Main combustion chamber (11) comprises heat collecting dome (22), grate (28) and rotatable sweeper (24). Air is supplied to main combustion chamber (11) from air transport pipe (31). Air used may be oxygen enriched air, which will lower off-gas volume. Oxygen enriched air also decreases the amount of nitrogen in air feed which advantageously reduces amount of NO _x formed during combustion. Grate (28) contains grate holes (29) so that air can pass through the fuel particles on the grate surface to provide turbulence to fuel particles. Grate holes (29) are aligned to provide air flow that is focused towards fuel feed inlet (21), meaning grate holes (29) are vertical at the center of grate (28) but their angle gets more acute radially, so that air flow is tangentially diverted from the outer surface of the fuel feed inlet (21). Concave structure of heat collecting dome (22) diverts air flow back towards grate (28), where fresh air is added to the flow, creating a double cyclone turbulent air flow. Turbulent combustion in the main combustion chamber (11) occurs with saturated mixture rich in fuel and poor in air. Grate (28) has a convex structure for facilitating spreading of fuel across the top surface of grate (28). Rotatable sweeper (24) consisting of fuel spreader (25) and slag mill (26) assists in improving combustion efficiency. Homogeneous distribution of fuel across grate (28) is achieved by fuel spreader (25), while slag mill (26) grinds slag build-up around fresh fuel particles. Burning fuel particles are suspended in the main combustion chamber (11) due to turbulence, which further minimizes slag build-up around fuel particles and allows improved combustion to occur. As a result, the efficiency of the system is greatly increased. Turbulent combustion across the main combustion chamber also prevents temperature variations (11), which in turn keeps sulfur emissions at a stable and low level. Figure 6 illustrates secondary combustion chamber (12) in detail. Secondary combustion chamber (12) comprises heat collecting dome (22), fuel feed inlet (20) and gas acceleration nozzle (32). Inside surface of secondary combustion chamber (12) is of refractory material. Secondary combustion chamber (12) is where second stage combustion occurs. Uncombusted air and flue gas enter into secondary combustion chamber (12) from main combustion chamber (13) via dome openings (23). The higher volume of secondary combustion chamber (12) allows CO and other gases to expand and combust more freely. The outer surface of fuel feed inlet (20) and the lateral and concave top surface of secondary combustion chamber (12) allow formation of double cyclone turbulent air flow inside secondary combustion chamber (12) for more efficient combustion of CO. Completely combusted flue leaves secondary combustion chamber (12) through gas acceleration nozzle (32) and is released into the atmosphere, or transferred for further processing, such as scrubbing, filtering and/or electrostatic precipitation, via funnel pipe bend (33).

Figures 7 and 8 illustrate an embodiment of turbulent combustion incinerator (100- For convenience, the numerals assigned to each part remain unchanged. Those that are changed are denoted by an apostrophe, such as fuel hopper (150. ^In this embodiment, the fuel is fed from the bottom of turbulent combustion incinerator (100 by fuel hopper (150- The fuel is transferred along the fuel feed pipe (200 by fuel transfer auger (170 driven by fuel feeder motor (160- Fuel is fed directly into grate (28) from the bottom by elbow-shaped fuel feed inlet (210- In order to not interfere with air transport pipe (31), fuel feed pipe (200 is placed eccentrically to grate (28). Fuel is evenly distributed across grate (28) by rotatable sweeper (24), rotated by sweeper motor (27) to ensure more efficient combustion.

Figure 9 illustrates another embodiment of turbulent combustion incinerator (10"). In this embodiment, heat collecting dome (22) contains dome channels (37). Dome channels (37) are aligned to provide air flow that is focused towards the part of fuel feed inlet (21) that is beneath gas acceleration nozzle (32), meaning the angle of dome channels (37) gets more acute radially, so that air flow is tangentially diverted from the outer surface of the fuel feed inlet (21). Concave structure of the top of secondary combustion chamber (12) diverts air flow back towards heat collecting dome (22), creating a double cyclone turbulent flow of air and combustion gases coming from main combustion chamber (11), thereby expediting further oxidation of combustion gases such as CO.

In a nutshell, the present invention proposes a turbulent combustion incinerator (10) comprising of a main combustion chamber (11) and a secondary combustion chamber (12) for turbulent combustion of fuel.

In a first variation of the invention, said main combustion chamber (11) comprises a heat collecting dome (22), a grate (28) and where said heat collecting dome (22) has concave shape and said grate (28) has convex shape; and said grate (28) has grate holes (29) on said convex surface; and said grate holes (29) are aligned to provide air flow focused towards the center of said main combustion chamber (11) so as to effectuate tangential diversion of air flow in the manner that burning fuel particles are suspendable in the main combustion chamber (11) due to generated turbulence whereby turbulent flow of air and fuel is achieved.

In a further variation of the invention, inclination of neighboring grate holes (29) with respect to horizontal plane is gradually decreased in the radial direction.

In a further variation of the invention, inclination of said grate holes (29) are vertical with respect to horizontal plane at the center of said grate (28) and their angle gets more acute radially.

In a further variation of the invention, solid or biomass fuel is usable.

In a further variation of the invention, said main combustion chamber (11) and said secondary combustion chamber (12) are divided by said heat collecting dome (22).

In a further variation of the invention, said turbulent combustion incinerator (10) comprises dome openings (23) such that flow of flue gas, fly ash and other volatiles between said main combustion chamber (11) and said secondary combustion chamber (12) is facilitated. In a further variation of the invention, a two-staged combustion is generated in said turbulent combustion incinerator (10).

In a further variation of the invention, two-staged combustion is effectuated such that combustion of solid or biomass fuel takes place in said main combustion chamber (11) and combustion of carbon monoxide and other flue gases takes place in said secondary combustion chamber (12).

In a further variation of the invention, inner surface of said turbulent combustion incinerator (10) is of refractory material (14) and the outside is insulated by ceramic fiber wool (13).

In a further variation of the invention, fuel is fed into the system from above by fuel hopper (15). In a further variation of the invention, said fuel hopper (15) comprises a fuel transfer auger (17) that is driven by fuel feeder motor (16) and mechanically borne by ball bearing (19).

In a further variation of the invention, said fuel hopper (15) is attached to the main body of said turbulent combustion incinerator (10) by support element (18).

In a further variation of the invention, fuel is transferred directly to the main combustion chamber (11) via fuel feed pipe (20) and fuel feed inlet (21).

In a further variation of the invention, said fuel feed inlet (21) is made of ceramic material resistant to temperatures above 1200°C.

In a further variation of the invention, air is blown into said main combustion chamber (11) from below through said grate holes (29) such that air is blown from below the fuel. In a further variation of the invention, said main combustion chamber (11) comprises a rotatable sweeper (24) for even distribution of fuel across grate (28).

In a further variation of the invention, said rotatable sweeper (24) is rotated by sweeper motor (27).

In a further variation of the invention, said rotatable sweeper (24) consists of fuel spreader (25) with at least one slag mill (26) for homogeneous distribution of fuel across a grate (28) and grinding slag build-up around fresh fuel particles.

In a further variation of the invention, outer surface of fuel feed inlet (20) and the lateral and concave top surface of said secondary combustion chamber (12) allow formation of turbulent air flow inside said secondary combustion chamber (12).

In a further variation of the invention, combusted flue gas leaves secondary combustion chamber (12) through gas acceleration nozzle (32). In a further variation of the invention, combusted flue gas leaving through said gas acceleration nozzle (32) is transferred for scrubbing, filtering and/or electrostatic precipitation via funnel pipe bend (33).

In a further variation of the invention, bottom ash produced by combustion is collected by ash collection cone (34).

In a further variation of the invention, bottom ash produced by combustion is removed by ash transfer auger (35).

In a further variation of the invention, bottom ash removed by ash said transfer auger (35) are disposed of with counter-weight cover (36). In a further variation of the invention, air used is oxygen enriched air.

In a further variation of the invention, fuel is fed into the system from below by fuel hopper (150. In a further variation of the invention, fuel hopper (150 comprises a fuel transfer auger (170 that is driven by fuel feeder motor (160-

In a further variation of the invention, fuel is transferred directly to the main combustion chamber (11) via fuel feed pipe (20) and fuel feed inlet (21).

In a further variation of the invention, fuel is fed directly into grate (28) from below by elbow-shaped fuel feed inlet (210- In a further variation of the invention, fuel feed pipe (200 is placed eccentrically to grate (28).

In a further variation of the invention, turbulent combustion incinerator (10) comprises a heat collecting dome comprising dome channels (37) to provide air flow focused towards the center of said secondary combustion chamber (12) so as to effectuate tangential diversion of air flow whereby turbulent flow of air and combustion gases is achieved. In a further variation of the invention, inclination of dome channels (37) with respect to horizontal plane is gradually decreased in the radial direction.