JP2627363B2 - Fluidized bed high water content waste combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed incinerator for fluidized bed incinerators and the like, which burns and incinerates highly hydrated waste such as beer wheat meal or pulp sludge.

[0002]

2. Description of the Related Art Conventionally, high-water content waste such as brewer's meal or pulp sludge containing a large amount of water, for example, 40 to 80%, is produced by blowing high-temperature air from a gas dispersion plate below a combustion chamber. It is put into a high temperature fluidized bed of about 750 to 850 ° C. formed by fluidizing a fluid medium such as sand, and instantaneously evaporates water in the high temperature fluidized bed to remove combustibles in waste. They are incinerated by burning.
The high-temperature exhaust gas discharged from the fluidized bed and having the same temperature as the fluidized-bed temperature is recovered at a high temperature by an exhaust heat boiler or an air preheater installed downstream of the exhaust gas outlet of the combustion chamber. The adjustment is performed, the steam is recovered in the exhaust heat boiler, and the combustion air for the auxiliary burner, which acts to keep the fluidized bed at a high temperature, is heated in the air preheater.

[0003]

The exhaust heat boiler and the air preheater are generally installed at the exhaust gas outlet of a combustion chamber of a combustion apparatus in which the exhaust gas is kept at the highest temperature to effectively recover high heat. Therefore, it is desired that the temperature of the exhaust gas be low on the downstream side of the exhaust gas duct so as to minimize the dissipation of the retained heat of the exhaust gas. However, for this reason, if an exhaust heat recovery device such as an exhaust heat boiler or an air heater is installed at a position facing the combustion chamber at the exhaust gas discharge section of the combustion device, that is, at a position where the heat transfer surface faces the fluidized bed. If there,
The heat of the fluidized bed is absorbed by the heat transfer surface by the radiant heat transfer, and the temperature of the combustion chamber or the fluidized bed decreases.

[0004] When the exhaust heat recovery device is an air preheater in particular, the water is upstream of the preheater itself, that is, upstream of the exhaust gas inlet to the air preheater in order to protect the preheater from high temperatures. It may be necessary to adjust the temperature of the exhaust gas by spraying to cool the exhaust gas temperature, but also in this case, similarly, the heat of the combustion chamber or the fluidized bed is absorbed by the cooling unit or the like by radiant heat transfer. As a result, the temperature of the combustion chamber or the fluidized bed decreases. For this reason, there is a problem that the temperature in the fluidized bed or the combustion chamber is not stably maintained at a high temperature, and the combustion of high-water content waste is not smoothly performed. The present invention has been made in view of such a problem, and a fluidized bed highly hydrated waste capable of effectively preventing temperature reduction of a combustion chamber or a fluidized bed and effectively performing exhaust heat recovery or exhaust gas cooling. The aim is to obtain a combustion device.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a fluidized medium is fluidized by hot air on a first gas distribution plate below a combustion chamber to form a hot fluidized bed, and a high water content waste is produced in the fluidized bed. Fluidized bed high water content waste combustion with a combustion exhaust gas exhaust section and a combustion exhaust gas temperature control section such as an exhaust heat recovery section or exhaust gas cooling section at the position facing the freeboard of the combustion chamber at the combustion exhaust gas discharge section. The device, traversing the freeboard portion to the freeboard portion above the fluidized bed of the combustion chamber, which is upstream of the flue gas discharge direction in the flue gas flow direction from the flue gas discharge portion ,
Radiant heat transfer of the high-temperature fluidized bed to the flue gas temperature control unit
A second gas dispersion plate for shielding is attached.

[0006]

When high-moisture waste is burned in a high-temperature fluidized bed formed by fluidizing a fluid medium with high-temperature air dispersed and supplied by a first gas distribution plate below a combustion chamber, the high-temperature waste is discharged. The flue gas flows into the second gas distribution plate installed in the freeboard portion above the fluidized bed in the combustion chamber, and is dispersed and discharged to the freeboard portion above the second gas distribution plate. Then, the high-temperature flue gas passes through the upper freeboard portion and is subjected to the action of exhaust heat recovery or exhaust gas cooling at a position facing the freeboard portion of the combustion chamber at the flue gas discharge portion of the combustion chamber, thereby controlling the temperature. Is done.

The second gas distribution plate is disposed between the flue gas discharge portion and the fluidized bed on the upstream side of the flue gas discharge portion of the combustion chamber in the gas flow direction. The gas dispersion plate shields the radiant heat of the high-temperature fluidized bed which is going to be transferred to the exhaust heat recovery unit or the exhaust gas cooling unit which faces the combustion chamber free board unit at the exhaust gas exhaust unit. Therefore, stable combustion is performed in the fluidized bed or the combustion chamber without lowering the temperature of the fluidized bed or the combustion chamber. The exhaust heat recovery section is installed at a position where the combustion exhaust gas is at the highest temperature, and the gas is uniformly introduced into the section by the second gas distribution plate, so that a predetermined exhaust heat recovery is effectively performed. Done. The second gas distribution plate also serves to prevent combustion gas from flowing in the space of the combustion chamber located above the fluidized bed and to send the combustion gas upward evenly in cross section. Even when only the exhaust gas cooling unit is installed facing the combustion chamber at the exhaust gas discharge port and the exhaust heat recovery unit is installed in the middle of the exhaust gas duct downstream of the exhaust gas cooling unit, the temperature of the exhaust gas is reduced to a predetermined temperature and the exhaust gas is exhausted. The heat recovery unit is protected from high temperatures, and waste heat recovery is effectively performed.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of a fluidized bed incinerator as a fluidized bed combustion apparatus of the present invention. In FIG.
An air chamber 2 is located at the bottom of the fluidized bed incinerator 1,
An auxiliary burner 3 is attached to the air chamber 2, and a combustion air intake 3a is formed. At the upper part of the air chamber 2, a first gas distribution plate 4 is mounted horizontally across the furnace body 1a, and a large number of gas distribution tubes 4a are mounted on the gas distribution plate 4. Above the first gas distribution plate 4, a combustion chamber 5
Is formed, and a screw feeder 9 as a waste feeder is attached to the side wall of the furnace body 1a so as to face the combustion chamber 5. Numeral 6 denotes a fluidized bed formed by fluidizing the fluid medium 6a by high-temperature air supplied from the auxiliary burner 3 of the air chamber 2 through the gas distribution plate 4 on the first gas distribution plate 4.

A second gas distribution plate 10 is attached to the free board section (empty tower section) 7 above the fluidized bed 6 of the combustion chamber 5 so as to cross the free board section 7. The second gas distribution plate 10 has a vertical gas distribution nozzle 10 formed by a straight pipe.
a are fixedly attached by a partition plate 10b located horizontally at the center. Gas dispersion nozzle 10
The upper and lower ends of “a” are opened to the upper free board section 8 and the free board section 7, respectively. A water cooling pipe 10c is provided between the gas dispersion nozzle 10a and between the gas dispersion nozzle 10a and the furnace body 1a.
Are fixedly attached to the partition plate 10b. The periphery of the water cooling pipe 10c, the partition plate 10b, and the gas dispersion nozzle 10a is covered with a refractory 10d. An upper free board portion 8 is formed above the second gas distribution plate 10, and an exhaust gas outlet 11 is formed above the upper free board portion 8.
An air preheater 13 as an exhaust heat recovery unit is installed in an exhaust gas duct 12 slightly above the exhaust gas outlet 11,
Although not shown, a number of heat transfer tubes (heat transfer portions) are located across the duct 12 and facing the upper free board portion 8. Air preheated by the combustion exhaust gas of the fluidized bed 6 in the air preheater 13 is taken into the air chamber 2 from the combustion air inlet 3a,
Or as air for fluidization and combustion in the fluidized bed 6.

In the fluidized bed incinerator 1 having such a configuration, high-temperature air of, for example, 1000 ° C. is supplied from the air chamber 2 to the combustion chamber 5 via the first gas dispersion plate 4 and the first gas dispersion plate 4 Above, the fluidized medium 6a is fluidized to form the fluidized bed 6. As the fluid medium 6a, sand such as silica sand having an average particle diameter of about 1 mm is used. The temperature of the fluidized bed 6 is 75
It is kept at a high temperature of about 0 to 850 ° C. Then, pulp sludge as waste containing about 60% of water is introduced into the fluidized bed 6 by the screw feeder 9, and the pulp sludge is heated by the high-temperature fluidized bed 6 and the water is instantaneously evaporated, The combustibles are fluidly burned. The flue gas of about 750 to 850 ° C. discharged from the fluidized bed 6 rises in the free board section 7 and the second
Into the many gas dispersion nozzles 10a of the gas dispersion plate 10 and uniformly dispersed into the upper free board portion 8 above the gas dispersion plate 10 and discharged. In the fluidized bed 6, about 80% of the combustibles are burned, and the remaining about 20% of the unburned parts are burned in the free board section 7 of the combustion chamber 5.

Then, the flue gas reaches the flue gas discharge port 11 of the fluidized bed incinerator 1, flows into the flue gas duct 12, flows into the air preheater 13 located there, and heats the heat transfer tube there. Thus, the combustion air flowing in the heat transfer tube is preheated to about 670 ° C. The preheated air is introduced into the air chamber 2 from the combustion air inlet 3a, and is used as combustion air or fluidized air. The temperature of the exhaust gas passing through the air preheater 13 is reduced to a predetermined temperature, and the temperature of the exhaust gas is adjusted.
After flowing downstream in the exhaust gas duct 12 and further heat recovery is performed by a waste heat boiler or another air preheater (not shown) located on the downstream side, after being subjected to dust collection by a dust collector, Is released to the atmosphere.

Thus, the air preheater 13 (exhaust heat recovery unit) is located facing the upper free board unit 8, but a second gas distribution plate is provided between the fluidized bed 6 and the exhaust gas outlet 11. 10
Is mounted across the furnace body 1a, the heat transmitted from the hot fluidized bed 6 by radiant heat transfer is shielded by the second gas dispersion plate 10 and is not absorbed by the air preheater 13. . Therefore, the temperatures of the fluidized bed 6 and the combustion chamber 5 do not decrease. Therefore, the pulp sludge having a high water content can be fluidly burned stably. Further, since the second gas distribution plate 10 imparts a required ventilation resistance to the exhaust gas flow, the second gas distribution plate 10 is prevented from drifting from the second gas distribution plate 10 to the upper free board portion 8 so that the exhaust gas is dispersed and supplied evenly in cross section. The exhaust gas can be evenly fed to the upper air preheater 13 and the air preheater 13 can efficiently recover heat. The exhaust heat of the exhaust gas can be effectively absorbed by installing the air preheater 13 near the exhaust gas outlet of the incinerator 1 where the combustion exhaust gas has the highest temperature.

On the other hand, the air preheater 13 is connected to its heat transfer surface (part).
When it is necessary to protect the gas from high heat or to prevent corrosion by harmful components contained in the combustion exhaust gas, for example, chlorine, a water spray device 14 as an exhaust gas cooling device is used as shown by a chain line in FIG. Although it is necessary to cool the combustion exhaust gas by installing water on the upstream side of the air preheater 13, it is possible to prevent the radiant heat of the fluidized bed 6 from being absorbed by the cooling water even in such a case. In addition, it is possible to prevent the temperature of the fluidized bed 6 and the air chamber 5 from decreasing. In this embodiment,
Although the case where the air preheater 13 is provided as the exhaust heat recovery unit in the portion of the exhaust gas outlet 11 facing the free board unit is shown,
Here, an exhaust heat boiler, an economizer, or the like that obtains steam by heating boiler water may be provided. Further, only the water spray device is attached at a position facing the free board portion in the portion of the exhaust gas discharge port 11, and only the cooling operation of the combustion exhaust gas is performed here. In some cases, exhaust heat recovery may be performed by providing the exhaust gas duct 12 on the downstream side of the exhaust gas duct 12. In the present embodiment, the case where the high water content waste is pulp sludge is shown, but high water content waste such as sludge, beer wheat cake, coffee bean cake, and tofu cake may be used.

[0014]

As described above, according to the present invention,
The second gas distribution plate effectively prevents radiant heat from the fluidized bed from being absorbed by the exhaust heat recovery device or the exhaust gas cooling device located facing the combustion chamber at the exhaust gas outlet of the combustion device. be able to. Therefore, it is possible to prevent the temperature of the fluidized bed or the combustion chamber from lowering, and to stably burn the highly water-containing waste. Further, the exhaust heat recovery can be performed at the exhaust gas outlet of the combustion device where the combustion exhaust gas has the highest temperature, and the exhaust heat recovery can be performed effectively. Furthermore, even when only the exhaust gas cooling unit is installed facing the combustion chamber at the exhaust gas outlet, and the exhaust heat recovery unit is installed in the middle of the exhaust gas duct downstream of the exhaust gas cooling unit, the temperature of the exhaust gas is reduced to a predetermined temperature and the exhaust heat is reduced. The recovery section can be protected from high temperatures,
Exhaust heat recovery can be performed effectively.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a fluidized bed incinerator as a fluidized bed combustion device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid bed incinerator 4 1st gas dispersion plate 5 Combustion chamber 6 Fluidized bed 7 Free board part 8 Upper free board part 10 2nd gas dispersion plate 10a Gas dispersion nozzle 11 Exhaust gas exhaust port 13 Air preheater (exhaust heat recovery) Part) 14 water spray device

Claims (1)

(57) [Claims] A fluidized medium is fluidized by high-temperature air on a first gas distribution plate below a combustion chamber to form a high-temperature fluidized bed, and high-humidity waste is burned in the fluidized bed. A fluidized bed high water content waste combustion device provided with a flue gas temperature control unit such as a waste heat recovery unit or a flue gas cooling unit at a position facing a free board of a combustion chamber in a flue gas discharge unit of the above. The freeboard section is traversed over the freeboard section above the fluidized bed of the combustion chamber, which is on the upstream side of the flue gas flow direction from the section, to the flue gas temperature control section.
2. A fluidized bed highly hydrated waste combustion apparatus according to claim 1, further comprising a second gas dispersion plate for shielding radiant heat transfer of said high temperature fluidized bed .