JPS5931642B2 - Combustion method in fluidized bed furnace - Google Patents

Description

Detailed Description of the Invention The present invention uses a natural desulfurizing agent such as sand or limestone or an artificial desulfurizing agent in a fluidized bed furnace for the purpose of increasing the heat load of the fuel, that is, improving the combustibility of the fuel. Fluidizing air is supplied from the lower part to form a fluidized bed, and in the fluidized bed, fuel such as heavy diesel oil, oily waste such as tank sludge, mixed fuel of oil and coal, so-called colloidal fuel, etc. Incineration materials (hereinafter referred to as fuels).

) relates to a method for burning the fuels in a fluidized bed reactor. In a conventional fluidized bed furnace, as shown in Figure 1, to burn light oil, kerosene, heavy oil, etc., a normal diffusion combustion burner, a burner gun 2 forming a so-called open flame, is inserted into the fluidized bed 1 of the fluidized bed furnace. However, in this case, the burner gun 2 inserted into the fluidized bed 1
The tip of the burner gun 2 is overheated by the high heat transfer of the high-temperature fluid medium, causing thermal decomposition (cracking) of the fuel oil, and carbon adheres to the tip of the burner gun 2, resulting in the nozzle at the tip of the burner gun 2 becoming clogged. .

Therefore, air atomization burners using high-pressure air (in this case, internal mixing or intermediate mixing chips are often used).

) was used to simply supply fuel, and combustion in the fluidized bed depended solely on the conditions within the bed. 1st
In the figure, 3 is a fuel inlet, 4 is an air supply port, 5 is a wind box, 6 is an air distribution plate, and 7 is a furnace wall.

In view of the above, the present invention uses a nozzle pipe 9 passing through an air dispersion plate 6 installed at the base of the fluidized bed as a burner gun body, as shown in FIG. The swirling flow of the air-fuel mixture turns into jet and is supplied into the fluidized bed. The length of the mixture jet injected into the layer (Jet.
On. depth), the initial bubble diameter in the layer, and the behavior of particles and gas at the bottom of the layer.

Therefore, in order to increase the heat load in the bed, good agitation of the fluidizing medium at the fuel injection point and good dispersion of the supplied fuels are required. Therefore, it is better if the ratio of the amount of conveyed air to the fuel is as large as possible and the initial jetting speed is as large as possible. However, if the ratio of the amount of conveyed air to the fuel becomes too large, a so-called blow-through phenomenon occurs within the bed, and the inside of the bed cannot be used effectively.

In other words, there is a certain appropriate ratio of the amount of air to the amount of fuel. Table 1 shows the results of an investigation by the inventors of the influence of G1/GT on combustion performance determined as CO emission concentration.

The smaller the value of the relative CO emission concentration ratio, the better the combustion performance. Here, the ratio of the so-called relative CO emission concentration ratio in the case of the present invention to the conventional method in which G1/GT was changed by setting the CO emission concentration in the case of the conventional method (Figure 1) to 1, and the results are shown in Table 1. As is clear from the fuel transport air ratio, G1
There is an optimal range for the value of /GT, and it needs to be 0.4 or more.

That is, in the present invention, the mixed fluid is ejected into the fluidized bed as (a) dinit, and in that case, (b)
The fuel transport air ratio G1/GT is set to 0.4 or more, and the mixed fluid of fuel and air, which is blown into the fluidized bed as dinit as described later, (c) flows so as to produce a swirling flow. By supplying this (a), (mouth),
The synergistic effect of (c) completely eliminates all the drawbacks of the conventional fluidized bed in the V1 fluidized bed furnace, and further contributes to improving the combustion performance in the fluidized bed furnace.

Next, according to research by the present inventors, at the same time as G1/GT, the insertion length H measured from the air distribution plate 6 in the fluidized bed of the burner head 10 of the nozzle pipe 9 that blows fuel into the fluidized bed is It was found that this affects the combustion performance of fuels in fluidized bed reactors. This is because the behavior of particles and gas changes depending on the distance from the air dispersion plate, and the mixing state of particles and gas changes. In order to obtain good combustion performance, fuel is directed to the location with the best mixing state. , the air mixture must be supplied. That is, the insertion length H of the burner head
It is desirable that the length be variable depending on the amount of fuel burned, that is, the heat load in the formation, and it is possible to change the length to the optimum length according to the load even during operation using a drive device such as a power cylinder. Closed.

Burner head insertion length H measured by the inventors
Table 2 shows the relationship between H and combustion characteristics when the length of the tube was varied from 5 to 150 m1.

Here, the relative CO emission concentration ratio is 150V with burner head insertion length H! The CO emission concentration was calculated by setting the CO emission concentration to 1. In this case as well, of course, as in Table 1, the smaller the value of the relative CO emission concentration ratio, the better the combustion performance. From the results in Table 2, H is 10 m7! It turned out to be L~20mm.

Furthermore, according to the research conducted by the present inventors, selecting a burner head that improves the mixing and diffusion of the fuel-air mixture into the fluidized bed in conjunction with the insertion length H of the burner head synergistically improves combustion performance with G1/G. The back-mixing of the fluid medium near the nozzle is increased due to the position where the fuel is ejected from the nozzle, making it possible to prevent the coking phenomenon and carbon adhesion at the nozzle outlet. It has the effect of preventing nozzle clogging by providing the blowing direction of the nozzle and swirling flow to facilitate the diffusion of fuel and air jet in the layer.
It has been found that the object of the invention of increasing the heat load of the fuel is achieved.

Examples of various burner head shapes that improve the mixing and diffusion of fuel air into the fluidized bed are shown in Figures 3, 1, 2, 3, 4, and 3.
5.

1 is an AA sectional view of 1, similarly 2 is a BB sectional view of 2,
3 is a CC sectional view of 3, 4, 4 is a DD sectional view, 5 is 5
A sectional view taken along line E-E is shown.

In either case, they are designed to give appropriate ejection speed, ejection direction, swirling flow, etc. to the fuel-air mixture so that the fuel-air mixture can easily diffuse into the layer.

Assuming that the CO emission concentration in the case of the burner head 1 in Fig. 3, which is not designed to throttle the spout or give a circulating flow to the fuel, is 1, the burner head corresponding to this value is as shown in Fig. 3.
The results obtained by the present inventors are expressed as the third
Shown in the table.

Based on the results in Table 3, when the ejection opening of the burner head is narrowed down, when the two-pronged flow shown in Table 3 is applied, and when the two-pronged flow is given,
It was found that the combustion performance was improved. Regarding the shape of the burner head, in Fig. 3, 4'1, 30~
This is a case where a swirling blade with an angle of 40 degrees is provided to create a swirling flow in the fuel/air mixture.

In FIG. 3, a number of small holes are radially bored in the nozzle outlet, which has the same effect as constricting the opening and providing a circulating flow.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of the fluidized bed portion of a fluidized bed furnace to explain the conventional combustion method, Fig. 2 is a sectional view of an embodiment using the burner according to the present invention, and Fig. 3 4 and 5 are cross-sectional views showing various shapes of the burner head of the nozzle pipe of a fluidized bed furnace, 1 is a cross-sectional view taken along line AA of 1, and 2 is a cross-sectional view taken along line B-2 of 2.
3 shows a CC sectional view of 3, 4 shows a DD sectional view of 4, and 5 shows an E-E sectional view of 5. DESCRIPTION OF SYMBOLS 1... Fluidized bed, 2... Burner gun, 3... Fuel inlet, 4... Air supply port, 5... Wind box, 6...
Air distribution plate 7... Furnace wall, 13... Chip, 9...
Nozzle pipe, 10... Burner head, 16, 18
...burner head opening, 17... constricted burner head opening, 19... winding vane, 21... radial small holes of burner head, 15... air inlet for fuel conveyance .

Claims (1)

[Claims] 1. In a fluidized bed furnace, the ratio G_1 between the amount of fuel conveying air G_1 introduced into the fluidized bed and the amount of air G_T required for combustion.
/G_T is adjusted to 0.4 or more so that the fuel carried by the air in the nozzle pipe becomes a jet of a mixture of fuel and air and is supplied into the fluidized bed. A combustion method in a fluidized bed furnace, characterized in that a swirling flow is given to fluid supplied from a burner head of a nozzle pipe that supplies fuel to the bed furnace. 2 In a fluidized bed furnace, G_1 and G introduced into the fluidized bed
The ratio G_1/G_T with _T is adjusted to 0.4 or more so that the fuel carried by the air in the nozzle pipe becomes a jet of a mixture of fuel and air and is supplied into the fluidized bed. Insert the fuel into the fluidized bed by setting the insertion height (H) of the burner head of the nozzle pipe from the air distribution plate in the fluidized bed to 10
A method of combustion in a fluidized bed furnace, characterized in that the combustion angle is adjusted to 20 mm to 20 mm, and a swirling flow is given to the fluid supplied from the burner head. In a fluidized bed furnace, G_1 and G_T introduced into the fluidized bed
The ratio G_1/G_T is adjusted to 0.4 or more so that the fuel carried by the air in the nozzle pipe becomes a jet of a mixture of fuel and air and is supplied into the fluidized bed.
And adjust H to 10 mm to 20 mm, and further adjust the cross-sectional diameter of the burner head opening to 77% of the nozzle pipe diameter.
-94%, or the opening is made into a large number of radial small holes, or a swirling vane is provided at an angle of 30 to 60 degrees with respect to the normal to the opening in the right-angled cross section of the nozzle pipe,
A combustion method in a fluidized bed furnace, characterized in that a swirling flow is generated in a mixture of fuel and air.