JPS6361562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed furnace, and more particularly to a fluidized bed furnace that reburns unburned components collected from combustion gas discharged outside the bed.

Fluidized bed furnaces, in which a fluidized medium such as sand is fluidized with air to form a fluidized bed, and combustion is performed in this fluidized bed, have high combustion efficiency. It is possible to combust materials with low combustibility, such as various industrial wastes, and has recently been used in various fields.

However, since a fluidized bed allows a large amount of air to pass through to fluidize the medium, depending on the type of fuel, the residence time in the bed is extremely short, and the empty column may be destroyed before combustion in the bed is completed. It will be scattered. Most of the fuel scattered in the sky tower section is burned in the sky tower section, but a considerable amount of unburned fuel is still discharged out of the furnace together with the combustion gas. Especially differential coal,
This tendency is remarkable when the collected ash, called EP ash, is used as fuel (incineration material). For example, when burning EP ash, the combustion in a fluidized bed means that all the supplied EP
It has also been reported that about 20% of the ash is unburned and the rest is scattered in the sky tower. For this purpose, unburned matter is recovered from the exhaust gas discharged from the fluidized bed,
It was either incinerated using dedicated incineration equipment such as a rotary kiln, or re-supplied to a fluidized bed for combustion. The method of refeeding the fuel to the fluidized bed can effectively recover the heat value of the supplied fuel, and is particularly effective in fluidized bed boilers, but the method of refeeding the fuel to the fluidized bed is particularly effective in fluidized bed boilers. The properties of the supplied fuel are different. Therefore, if unburned components collected from exhaust gas and newly supplied fuel are supplied to the same fluidized bed, it becomes difficult to stabilize combustion in the fluidized bed.

An object of the present invention is to provide a fluidized bed furnace capable of eliminating the above-mentioned problems and effectively burning unburned components collected from exhaust gas.

In short, this invention provides a fluidized bed furnace in which the air chamber of a fluidized bed furnace is partitioned to form a plurality of independent air chambers, and a fluidized bed section for combustion of unburned materials is formed in the upper part of the air chamber of one of the sections. Regarding.

Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, an air chamber is formed in the lower part of the perforated plate 2 of the fluidized bed furnace body 1, and this air chamber is separated by a partition plate 3 into a large main combustion air chamber 4a and a small reburning air chamber. It is divided into 4b. A is fluidized air supplied to each air chamber, and is distributed and supplied so that the air velocity ejected into the fluidized bed is higher in the re-combustion air chamber 4b than in the main combustion air chamber 4a. . A fluidized bed 5 is formed above each of the air chambers 4a and 4b, and a main combustion fluidized bed portion 5a is formed above the main combustion air chamber 4a. Fuel F is supplied to this main combustion fluidized bed section 5a and is combusted. The combustion exhaust gas G rises through the tower section 6 and is discharged to the outside, but some of the unburned fuel scattered outside the layer is burned in the tower section 6, and the rest is discharged to the outside as unburned matter. be discharged. When the fuel F to be supplied is pulverized coal, the unburned content (mainly unburned carbon) discharged to the outside as exhaust gas along with the ash content is about 20 to 30% of the total fuel supply amount.

The unburned components that flowed out of the furnace together with the exhaust gas G are collected in the dust collector 7. The unburned matter and ash collected by the dust collector 7 are re-supplied as unburned matter F' to the re-combustion fluidized bed section 5b formed in the upper part of the re-combustion air chamber 4b. Since the flow velocity of the air A flowing out from the reburning air chamber 4b is set higher than that flowing out from the main combustion air chamber 4a, the flow rate of the air A flowing out from the reburning air chamber 4b is higher than that of the air A flowing out from the main combustion air chamber 4a. The unburned matter is violently fluidized and supplied to the re-combustion fluidized bed section 5b, and is burnt well. Due to the difference in fluidization state between the two fluidized beds 5a and 5b, a kind of circulating flow occurs in the main combustion fluidized bed section 5a, and the ash in both fluidized bed sections floating near the surface layer of the fluidized bed rides on the circulating flow and becomes ash. The ash moves to the extraction pipe 8 side and is discharged from this extraction pipe 8 to the outside.

According to this embodiment, the unburned content is effectively re-burned, so that of the combustion residue such as ash that is finally discharged outside, the unburned content is approximately 1 to 2%, which is 1/10 to 1/10 of the conventional combustion residue.
It can be reduced to 1/20.

FIG. 2 shows a second embodiment. In this embodiment, a high-pressure air chamber 4c is formed between the main combustion air chamber 4a and the re-combustion air chamber 4b. From the high-pressure air chamber 4c, air is injected into the bed at a flow rate higher than that in the re-combustion air chamber 4b, thereby forming an air curtain portion 5c in the fluidized bed above the high-pressure air chamber 4c. By forming the air curtain section 5c, the fluidized bed 5 can be further clearly divided into a main combustion fluidized bed section 5a and a re-combustion fluidized bed section 5b.
The unburned fraction F' supplied to the re-combustion fluidized bed section 5b is combusted in this fluidized bed section. In this case, it is not expected that the ash will move to the main combustion fluidized bed section 5a due to the air curtain section 5c, so the ash extraction pipe 8' provided in the reburning fluidized bed section 5b will separate the ash from the main combustion fluidized bed section 5a. Extract the ash separately.

By implementing the present invention, unburned components that were conventionally discharged to the outside are combusted, so the heat recovery efficiency relative to the amount of fuel supplied is good, and the thermal efficiency can be particularly improved in a fluidized bed boiler.

It is also economical since there is no need to install a special incinerator for burning unburned materials, and since the amount of unburned materials in the combustion residue is greatly reduced, the amount of combustion residue emissions itself can also be reduced. It exerts various effects such as

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fluidized bed furnace showing a first embodiment of the present invention, and FIG. 2 is a sectional view of a fluidized bed furnace showing a second embodiment. 1... Fluidized bed furnace main body, 4a... Main combustion air chamber, 4b... Re-combustion air chamber, 4c... High pressure air chamber, 5... Fluidized bed, 5a... Main combustion fluidized bed section,
5b...Fluidized bed section for re-combustion, 8,8'...Ash removal pipe, A...Fluidized air, F...Fuel, F'...
Unburned matter, G...Exhaust gas.

Claims (1)

[Claims] 1. The air chamber of the fluidized bed reactor body is divided into two or more sections, one of which is used as a re-combustion air chamber, and at least one of the other sections is used as a main combustion air chamber, A re-combustion fluidized bed section for burning unburned matter is formed in the upper part of the re-combustion air chamber, and a main combustion fluidized bed section is formed in the upper part of the main combustion air chamber. A fluidized bed furnace characterized in that the combustion state is higher than that in the main combustion fluidized bed section, and combustion residue is discharged to the outside through an ash extraction pipe. 2. A high-pressure air chamber is formed between the main combustion air chamber and the re-combustion air chamber, and an air curtain portion is formed in the fluidized bed above the high-pressure air chamber. Fluidized bed furnace. 3. The fluidized bed furnace according to claim 1 or 2, characterized in that ash extraction pipes are formed in both the main combustion fluidized bed section and the re-combustion fluidized bed section.