LV13994B - Burner of solid fuel with definite zones for pyrolysis, reduction and oxidation - Google Patents

Abstract

The invention concerns a solid organic fuel burner and a fuel burning method to be used in boiler heat generation equipment, technological devices or carbon monoxide gas generation plants. The offered burner for solid fuel combustion, containing a housing 1, and a feeder hatch 4 placed in the top part of the housing 1; characteristic feature of the burner: air nozzles 2 containing the air inlet 3 and placed in the bottom part of the housing are arranged at the exhaust end. Oxidation air supply 8 is placed in the top part of the housing 1 behind the air nozzles 2 placed in the bottom part of the burner housing 1. This burner ensures full secondary combustion, thereby increasing the burner efficiency and reducing maintenance costs. Characteristic feature of the method: the fuel filled in the burner housing 1 is being heated by the thermal radiation generated by the flame; it is moved to the burner end where the air coming from nozzles 2 placed in the bottom part is being blown through the heated fuel layer so that incomplete combustion takes place; the generated gases are mixed with air coming from the air supply 8 placed in the top part, and burn with flame.

Description

The present invention relates to a solid organic fuel burner and a method for burning fuel for use in boiler heaters, process equipment or carbon monoxide generators.

Analysis of prior art

Known burner designs with automatic fuel supply generally employ one of three types of combustion, which is characterized by the flame-burning of the fluidized bed or fuel surface. All types of these burners are described in detail in Wood Pellets in Finland - Technology, Economy and Market, Alakangas, E., Paju P. (Jyvakyla VTT Processes, 2002).

The first type involves top-to-bottom firing. It is used in fireplaces. This design has tar problems and requires frequent cleaning as unheated pellets rapidly enter the combustion zone, which lowers the combustion temperature and produces tar.

The second type involves feeding the fuel from below, forming a fuel hill on which air is blown. Here the flaws appear when stopping the burning. In the standby mode, the tar is released, which evaporates from the bottom layer of the fuel under the influence of the temperature of the unburned fuel and condenses on the heat exchange surfaces of the boiler. The air stream from the burner tends to blow away coal particles and further action does not help burn tar and coal from the surfaces, so frequent cleaning maintenance is required.

The third type comprises a horizontal burner on a sloping floor grate, where air is supplied from below from the bottom of the chamber. At a temperature of 300 ° C with air supply, volatile substances begin to burn on the surface and produce already burnt or hard-to-burn substances - carbon dioxide, water vapor and tar, thus interfering with the intended secondary combustion of the gases. This type of burner is described in patent application EP2032896 (SKI F23B40 / 06) "Pellet burner" and patent application EP1950272 (SKI C10J3 / 30) "Device and method for heat treatment of pellets or wood chips".

The above installations burn the fuel to the surface, further combustion of unburned gas and vapor products is attempted with additional air and extended flame, but this combustion mixture contains a large amount of already burnt or hardly combustible substances, eg tar, so incineration is often incomplete and boiler installations need to be cleaned. tar and soot deposits.

The object of the invention is to provide a burner which provides a complete secondary or final combustion process without creating sediment such as tar.

Summary of the Invention

The object of the present invention is achieved by providing a burner for solid fuel combustion (see burner design variants, headings 1-5), comprising a housing, an inlet manifold mounted above it, and air nozzles located above the fuel, and air jets located below the fuel in the bottom or floor of the housing, creating a split air stream above and below the fuel. This burner is characterized in that the air nozzles at the bottom of the housing containing the air inlet are arranged at the outlet end. In addition, the floor at the bottom of the burner body is inclined and said floor can be movable, further improving the flow of fuel to the burner. In addition, oxidation air or upper air nozzles may be located at the top of the burner body, behind the air nozzles at the bottom of the burner body; this solution lowers the temperature in the nozzle area. Alternatively, the fuel filler flap can be used instead of the top nozzle. This allows the fuel to be transported along with the upper air provided by the pneumatic transport unit provided with an air duct, metering unit, fan and tank.

In addition to the burner described above for the purpose of the invention, there is provided a process (see description of claims 6 to 10) for burning solid fuel, characterized in that the fuel contained in the burner body is heated by the flame heat radiation, resulting in pyrolysis. . The following fuel moves the preheated fuel to the nozzles on the underside of the burner end, from which exhaust air is blown through the heated fuel layer for incomplete combustion. Gaseous substances and vapors resulting from incomplete combustion mix with the upper air previously supplied from the filling port or nozzles, providing further flame combustion. In addition, placing the upper nozzles closer to the burner end behind the lower nozzles also removes the flame from the fuel. In addition, if the fuel feed rate significantly exceeds the burner's ability to burn all fuel, heated coal is released from the burner. In addition, the flame is led down through the coal bed, generating a flood and hydrogen. In addition, water vapor or water vapor and oxygen are added to the combustion process to an acceptable stable combustion level to generate "water gas" or "water-oxygen gas".

The following drawings illustrate the invention in greater detail:

-1. fig. Burner first model;

- Fig. 2 Second burner model with sloping floor and remote combustion;

- Fig. 3 Burner third model - gas generator;

- Fig. 4 Construction of lower air nozzle;

- Fig. 5 Fuel feed mechanisms: (a) directly to the burner, (b) pneumatic. The symbols used in the drawings are: 1 - burner housing, 2 - lower air nozzle, 3 5 lower air inlet, 4 - fuel filler flap, 5 - burner floor, 6 - ash, 7 - flame pipe, 8 - upper air inlet nozzles, 9 - hopper, 10 - snail conveyor, 11 - air shutter, 12 - fan, 13 - pneumatic transport hose, 14 - vertical shaft, 15 - troughs, 16 - generator gas exhaust, 17 - fuel, 18 - coal.

The first model of the burner (Fig. 1) comprises a horizontal body 1 with a flat floor 5 and an arch above it. At the top of the chamber is a top hatch for feeding pellets 4, which is also used as an upper air inlet 8. The bottom air inlet nozzles 2 are integrated into the floor at the exhaust end of the burner. The lower air nozzles 2 are made of ceramic, which is connected to a metal pipe 3.

The burner in this model works as follows: the fuel feeds into the burner through the filler port 4, which also serves as the upper air inlet 8; on the floor 5, solid fuels 17 are first heated by the flame radiation and pyrolysis; the fuel coming from the filler port 4 moves the preheated fuel to the end of the burner with air nozzles 2; the air stream burns and the gas and vapor are blended with the upper air in an abundance of fuel; at the flame pipe 7 the flame starts to burn. This burner design is similar to the third type of known burner, but differs from the bottom air supply method, which completely alters the burning pattern and results.

The second burner model for high ash fuel (Fig. 2) includes a horizontal body 1 with a sloping floor 5 and an arch above it. A burner hatch 4 is provided at the top of the burner at the top for supplying fuel, with bottom air inlet nozzles 2 embedded in the floor at the burner exhaust end, from which air is discharged in a horizontal direction. An upper or oxidation air duct 8 is connected to the flame tube 7. During combustion, the inclination of the floor 5 helps the fuel to move, the position of the lower air nozzles 2 dispenses the temperature concentration and leaves ash under the nozzles. The flame area is removed by introducing the upper air through a separate air duct 8 into the flame pipe 7. This ensures that the fuel and ash temperatures in the combustion chamber are kept as low as possible, reducing the ash and slag collapse of low quality fuels.

The third model of the burner - the gas generator (Fig. 3) - has a vertical shaft 14 with grates 15 for receiving coal 18 and a generator gas exhaust pipe 16. The gas generator burner has a different pellet feed rate, which causes unburned but already charred pellets to fall from in the vertical shaft of the burner on the grates. The flame in the burner passes through the coal layer and generates fuel gas.

Depending on the power of the burner and the amount of fuel, fuel injection into the burner combustion chamber is effected by gravity, mechanical feeding or by combining the two previous supply variants. Mechanical fuel delivery is possible with a auger conveyor, through the feed hatch 4 or directly into the burner (Fig. 5a), with a sliding shutter through the feed hatch or directly into the burner, or with a pneumatic conveyor (Fig. 5b) and the rotary shut-off valve 11 dispenses a quantity of granules. The fan 12 conveys the pellets through the air duct 13 to the supply hatch along with the upper air of the burner.

Claims (9)

1. A solid fuel burner comprising a casing, a filler port, and air jets above the fuel and a casing located at the top of the casing. 5 air jets located at the bottom or floor below the fuel creating a split air stream above and below the fuel, characterized in that the air jets (2) at the bottom of the housing containing the air inlet (3) are arranged at the outlet end. Burner according to Claim 1, characterized in that the floor (5) at the bottom of the burner body (1) is inclined, said floor (5) being movable. 10th Burner according to claim 1 or 2, characterized in that the upper air nozzles (8) are located behind the air nozzles (2) located at the bottom of the burner body (1). Burner according to one of Claims 1 to 3, characterized in that the air nozzles (8) located at the top are connected to the filling port (4). Burner according to Claim 4, characterized in that the fuel is filled and topped 15 air intake is provided by a pneumatic air duct transport unit equipped with a tank and metering unit. Method for burning solid fuel in a burner according to any one of the preceding claims, characterized in that the fuel (17) filled in the burner body (1) is heated by the heat of burning of the flame (7) by moving it to the end of the burner. In the nozzles (2) 20, air is blown through the heated bed of fuel (17) and incomplete combustion occurs, whereby the resulting gases are mixed with the air from the nozzles (8) at the top, which burns with flame. A method according to claim 6, characterized in that the upper nozzles ( 8) are located behind the lower nozzles (2). Method according to claim 6 or 7, characterized in that the fuel (17) feed rate significantly exceeds the burner's ability to burn all the fuel (17) and the flame (7) releases heated coal (18) from the burner. Method according to claim 8, characterized in that the flame (7) is led down through the coal (18) layer, generating a flood and hydrogen. A process according to claim 9, characterized in that water vapor or water vapor and oxygen are added to the combustion process to an acceptable stable combustion level to generate "water gas" or "water-oxygen gas".