JP3038533B2 - Powder combustion burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus in a heat utilization field such as a general industrial boiler, a power generation boiler and a heating furnace.
In particular, the present invention relates to a powder combustion burner suitable for burning powder such as pulverized coal, waste plastic, wood chips, and paper.

[0002]

2. Description of the Related Art In a conventional powder combustion burner, FIG.
As shown in FIG. 7, one fuel ejection pipe 1 for burning fuel such as oil or gas is disposed at the center, and a fuel ejection port 7 is provided at the tip of the fuel ejection pipe 1. The flame holding plate 6 is arranged on the outer circumference in the vicinity. A combustion air supply pipe 3 is disposed outside the fuel ejection pipe 1, and waste plastic is contained in a combustion air flow path 3 a formed between the combustion air supply pipe 3 and the fuel ejection pipe 1. A plurality of powder ejection pipes 5 for pneumatically transporting powder such as the above and ejecting the powder into the furnace are provided. Further, a combustion air supply pipe 3
An ignition burner 10 is arranged on the outer periphery of the furnace, and penetrates the refractory material 9 of the furnace. A powder conduit 8 is connected to each powder ejection pipe 5 as a powder ejection mechanism.

[0003] In such a powder combustion burner, a plurality of powder conduits for supplying powder to each powder ejection pipe are piped in front of the powder combustion burner. It is an obstacle for maintenance and inspection. Also, in order to supply the powder uniformly to each powder ejection pipe, special equipment for uniformly distributing the powder is required, and since this equipment is not integrated with the powder combustion burner, It is necessary to secure space for installing this equipment.

[0004] In recent years, with the development and diversification of industry, the amount of waste plastic discarded as industrial waste or general waste has been increasing year by year. Examples of such waste plastic treatment methods include material recycling, thermal recycling, simple incineration, and landfilling. Simple incineration and landfilling are merely intended for the treatment, and waste plastics are effectively used. It has not been used. On the other hand, it is most preferable if the material can be recycled. However, there are many obstacles to recycling and commercializing waste plastics mixed with various kinds of plastics, and this leads to an increase in cost.

Therefore, as the most practical and effective processing method, various thermal recycling methods have been proposed in which waste plastic is burned as fuel and the calorific value is recovered. Originally, plastics have a combustion characteristic higher than that of coal using petroleum as a main raw material, and even waste plastics have a high commercial value from the viewpoint of fuel. As one of the thermal recycling methods for waste plastics, for example, there is a method in which waste plastics are pulverized into finely pulverized particles, conveyed by air, burned by a burner, and heat recovered by a boiler.

[0006] The waste plastic powder is a low-melting substance that melts at, for example, 200 to 300 ° C. If such a low-melting powder is burned using a conventional heavy oil burner or slurry burner, a flame is generated. The powder is heated to the melting point or higher by the radiant heat from the burner or the burner tile and melts, and the tip of the burner is closed, or a large lump or flaky molten material falls from the tip of the burner, or in a furnace. During floating, there is a problem that incomplete combustion occurs due to insufficient surface area. Therefore, in order to prevent the powder from being melted at the powder ejection port by utilizing the cooling effect of the combustion air, a plurality of powder ejection pipes are arranged in the combustion air flow path as described above. However, the powder conduit connected to each powder ejection pipe has the same problem as described above.

[0007]

In a conventional powder combustion burner, a plurality of powder conduits are turbulent around a combustion device, which hinders maintenance and inspection. There is a problem that it is necessary to secure an installation space for equipment for uniformly supplying the body. Further, when powder is fed in a direction perpendicular to the powder ejection tube by the powder conduit, the amount of powder ejected from each powder ejection tube becomes non-uniform, and there is a problem that stable combustion cannot be performed.

It is an object of the present invention to provide a powder combustion burner in which the amount of powder ejected from each powder ejection tube is made uniform and stable combustion can be performed even with waste plastic powder.

[0009]

In order to achieve the above object, a powder combustion burner according to the present invention is provided with a fuel ejection pipe for ejecting a fuel such as oil or gas, and a fuel ejection pipe disposed outside the fuel ejection pipe.
A combustion air supply pipe provided, a plurality of powder ejection pipes disposed in a combustion air flow path formed between the combustion air supply pipe and the fuel ejection pipe, For body ejection pipe
In powder combustion burner comprising a supplying powder supply mechanism powder to be air entrained, the powder supply mechanism, before
A hollow annular powder supply chamber through which the fuel supply pipe is inserted ,
It is formed by at least one of the powder conduit is connected to the circumferential tangential direction of the powder supply chamber, wherein the plurality of powder ejected
The powder end is fixed to the annular end face of the powder supply chamber by
The powder supply tube is connected to the body supply chamber.
It is formed in a trumpet shape whose diameter increases toward the body supply chamber.
The ejection port of the powder ejection tube is closer to the ejection port of the fuel ejection tube.
Upstream of the combustion air supply pipe.
It is configured to be disposed between the inner wall and the air gap .

The powder may be a waste plastic.

[0011]

According to the present invention, a powder supply chamber communicating with each of the powder ejection pipes is provided, and at least one powder conduit is connected in a tangential direction of the powder supply chamber. Since it flows with air along the inner and outer peripheral surfaces of the powder supply chamber and is always supplied to each powder ejection pipe at a constant rate, the amount of powder ejected from each powder ejection pipe is the same. The particle size distribution is also the same, uniform ejection is obtained, and a stable combustion state is achieved. In addition, by arranging a plurality of powder ejection pipes in the combustion air flow path, even if it is a low melting point powder obtained by pulverizing waste plastic, it is easy to be melted by strong radiant heat from a flame or refractory material. Since the powder is conveyed while being cooled to a melting temperature or lower by the combustion air flowing through the air flow path and is injected into the furnace, the powder before injection in the powder injection pipe is prevented from being melted. Accordingly, troubles such as blockage of the ejection pipe due to melting of the powder and incomplete combustion due to agglomeration are prevented, and the powder is stably burned for a long period of time. Furthermore, since each powder ejection pipe and the powder supply chamber are integrated, attachment and detachment to and from the combustion air supply pipe are facilitated, and the number of steps for assembly and maintenance and inspection is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, a fuel injection pipe 1 which is inserted in a fuel injection pipe insertion guide pipe 2 which is disposed at the center and has a flame-holding plate 6 attached to a tip to supply fuel such as oil or gas. A fuel jet port 7 attached to the tip of the fuel jet pipe 1, a combustion air supply pipe 3 arranged outside the fuel jet pipe 1, and the combustion air supply pipe 3 and the fuel jet pipe 1. It is provided with a plurality of powder ejection pipes 5 arranged at equal intervals in the combustion air flow path 3a formed therebetween, and a powder supply mechanism for supplying powder to each powder ejection pipe 5. In a powder combustion burner, a powder supply mechanism is configured such that an end of each powder ejection pipe 5 is fixed by pipe end welding or the like, and a hollow annular powder supply that communicates with each powder ejection pipe 5. Room 4 and
One or more powder conduits 11 connected in a circumferential tangential direction of the powder supply chamber 4 are formed.

The powder supply chamber 4 has a flange on the side of the combustion air supply pipe 3 removably screwed to the flange of the combustion air supply pipe 3 by means of bolts and the like, and a central portion thereof is a guide pipe 2 for inserting a fuel ejection pipe. After passing through, the structure is sealed with the outside air. The end portion of the powder ejection tube 5 fixed to the powder supply chamber 4 is formed into a trumpet shape as shown in the figure so that the powder can easily flow in. Similarly, the powder conduit 11 and the powder supply chamber 4 are formed. May also be molded in a trumpet shape. Further, as shown in FIG. 2, a plurality of powder conduits 11a and 11b may be provided in accordance with the amount of powder, and a powder distribution plate 12 may be provided in those branch pipes. The powder is pulverized coal of 100 μm or less, 10
Any powder such as waste plastic, wood chips and paper chips having a size of 00 μm or less may be used, or a mixed powder thereof may be used. In addition, the waste plastic may be flakes of several mm square other than the particle shape, for example, a crushed PET bottle or a crushed plastic film.

Next, the operation of this embodiment will be described with reference to FIGS. 1, 3 and 4. A predetermined amount of spray vapor and a predetermined amount of combustion air are supplied to the fuel ejection pipe 1 and the combustion air supply pipe 3, respectively, and in this state, a predetermined amount of, for example, C heavy oil is supplied from the fuel ejection port 7 through the fuel ejection pipe 1 to the furnace. And is mixed with combustion air, ignited by an ignition burner 10 and burned. After the combustion of the fuel C ignited in this way is stabilized, waste plastics such as polyethylene, polypropylene and polystyrene are removed by, for example, 1000 μm.
m, and the gas-solid mixture obtained by mixing the waste plastic powder and air is passed through the powder ejection pipe 5 and flows through the combustion air flow passage 3a to a combustion air at a melting temperature of, for example, 200 or less. The powder is cooled to 300 ° C. or lower, and is injected into the furnace from each powder ejection pipe 5 and burned.

On the other hand, the transfer of powder to each powder ejection pipe 5
Since the powder conveyed by air flows in the direction of the arrow along with the air along the inner peripheral surface and the outer peripheral surface of the powder supply chamber 4 and the powder is always supplied to each powder ejection pipe 5 by a constant amount. The amount of powder ejected from the powder ejection pipe 5 is all the same and the particle size distribution is also the same, so that a uniform and stable powder ejection can be obtained, and the fuel and the fuel such as oil or gas from the fuel ejection port 7 can be stably burned. Combustion state. Therefore, it is sufficient if there is an air amount and a flow velocity at which the powder in the powder supply chamber 4 flows one or more rounds along the outer circumference on the inner wall surface.
Preferably, one or two pipes are provided, and 4 to 8 powder ejection pipes 5 are preferably provided. Further, since the powder ejection pipes 5 and the powder supply chamber 4 are integrated, the attachment / detachment to / from the combustion air supply pipe 3 is facilitated, and the powder ejection pipes 5 are required to assemble products or to be disassembled during maintenance and inspection. Assembly man-hours are reduced.

However, even if the powder supply chamber 4 is provided as shown in FIG. 5, if the powder is fed from the powder conduit 13 toward the center of the powder supply chamber 4 in a direction perpendicular to the powder ejection pipe, Of the plurality of powder ejection pipes, more powder is supplied to the powder ejection pipe near the powder conduit 13 than is supplied to the other powder ejection pipes. The particle size distribution of powder ejected from each powder ejection tube is caused by the fact that the amount of powder ejected from the body ejection tube is not uniform and the ease of powder entry into the flow of carrier air varies depending on the particle size of the powder. However, it is necessary to pay attention to the fact that uniform and stable combustion cannot be performed due to the difference between the two.

Preferably, the ejection port of the powder ejection pipe is opened slightly inside, that is, on the upstream side of the ejection port of the oil / gas ejection pipe. This can prevent the powder tip from being heated by radiant heat and effectively prevent the powder from being melted before being ejected. It is preferable that the inner peripheral surface of the ejection port of the powder ejection tube is coated with ceramic or that the ejection port has an arc-shaped cross section. As a result, the effect of preventing the powder from being blocked at the ejection port is improved. Further, the powder ejection pipe may be formed as a double pipe and cooled with a cooling fluid such as water. The number of powder ejection tubes is not particularly limited, but is preferably an even number such as six or eight, and is preferably arranged at equal intervals on the outer periphery of the combustion air flow path.
After the combustion of the powder is stabilized, it is preferable to reduce the supply amount of fuel such as oil or gas by a predetermined amount.

In order to confirm the effect of the present embodiment, 50 kg / hr of waste polystyrene powder having an average diameter of about 250 μm and 200 kg / hr of heavy oil A were co-fired. As shown in FIG. 2, the waste polystyrene powder is conveyed to the powder supply chamber together with air from two powder conduits arranged in a circumferential tangential direction of the powder supply chamber, and is supplied to the eight powder ejection pipes. Erupted. The amount of powder ejected from each powder ejection tube was all constant and uniform, and combustion was stable for a long time.

According to the present embodiment, by improving the heavy oil burner to burn the powder, the existing combustion device is effectively used to burn the low melting point powder such as waste plastic. Therefore, it is possible to cope with the technology for converting waste plastic into powder fuel without requiring special capital investment.

Further, by providing a plurality of powder ejection pipes in the combustion air flow path, a gas-solid mixture obtained by mixing waste plastic powder and air can be cooled to a temperature below the melting point of the waste plastic powder. Therefore, the waste plastic powder can be stably burned by preventing the powder ejection pipe and the ejection port from being clogged due to the melting of the waste plastic.

Further, since a powder supply chamber communicating with each powder ejection pipe is provided and one or more powder conduits are connected in a tangential direction of the powder supply chamber, powder ejection from each powder ejection pipe is performed. The amounts are all the same and the particle size distributions are also the same, so that a uniform ejection is obtained and a stable combustion state is maintained for a long time. And since each powder ejection pipe and the powder supply chamber are integrated, attachment / detachment to / from the combustion air supply pipe becomes easy, and the man-hours for assembly and maintenance and inspection are reduced.

[0022]

According to the present invention, since a plurality of powder ejection pipes provided in the combustion air flow path are provided with a powder supply mechanism, the amount of powder ejection from each powder ejection pipe is constant. Thus, even the low melting point waste plastic powder is prevented from melting by cooling with combustion air, and the powder can be stably and completely burned for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a front view showing an arrow AA in FIG. 1;

FIG. 3 is a diagram illustrating the operation of the present embodiment.

FIG. 4 is a diagram illustrating the operation of the present embodiment.

FIG. 5 is a diagram illustrating an operation related to the present embodiment.

FIG. 6 is a cross-sectional view showing a conventional technique.

FIG. 7 is a front view as viewed in the direction of arrows BB in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel ejection pipe 2 Fuel ejection pipe insertion guide pipe 3 Combustion air supply pipe 4 Powder supply chamber 5 Powder ejection pipe 7 Fuel ejection port 11 Powder conduit 12 Powder distribution plate

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masao Koyama 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Engineering & Shipbuilding Co., Ltd. (72) Inventor Masaaki Nonaka 3-1-1 Tamama, Tamano-shi, Okayama Mitsui (72) Inventor Tetsuya Okano 3-1-1, Tamano-shi, Tamano-shi, Okayama Prefecture Mitsui Engineering & Shipbuilding Co., Ltd. No. 3 No. 38 Inside Volcano Co., Ltd. (56) References JP-A-3-211304 (JP, A) JP-A-6-11109 (JP, A) Japanese Utility Model 1983-27623 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) F23D 1/00 F23C 1/10 F23G 7/12 ZAB

Claims (2)

(57) [Claims] 1. A fuel ejection pipe for ejecting fuel such as oil or gas, a combustion air supply pipe disposed outside the fuel ejection pipe, and a fuel air supply pipe and a fuel ejection pipe. A powder comprising: a plurality of powder ejection pipes arranged in a combustion air flow path formed therebetween; and a powder supply mechanism for supplying powder to be conveyed to each powder ejection pipe by air. In the body combustion burner, the powder supply mechanism is configured such that the fuel supply pipe is inserted therethrough.
Powder and powder supply chamber of the hollow annular is formed by at least one of the powder conduit is connected to the circumferential tangential direction of the powder supply chamber, the tube end of the plurality of powder injection portion to be Body supply
Fixed to the annular end face of the chamber and communicated with the powder supply chamber.
And the end of the powder ejection tube is moved toward the powder supply chamber.
Formed into a trumpet shape with a large diameter
The outlet is located upstream of the fuel outlet of the fuel outlet tube.
And a gap is provided between the air supply pipe and the inner wall of the combustion air supply pipe.
A powder combustion burner characterized by being arranged in a manner as described above. 2. The powder combustion burner according to claim 1, wherein the powder is waste plastic.