JPH06265121A - Fluidized bed type combustion device - Google Patents

Abstract

PURPOSE:To prevent corrosion at a high temperature, produce steam of high temperature and high pressure and increase a heat recovery by a method wherein dust fuel, fluidizing medium and flowing air are supplied to a combustion zone, a heat transfer surface for recovering heat is arranged in the heat recovering zone, only the fluidizing medium of high temperature in the combustion zone is circulated and combustion gas of low temperature is supplied to make a fluidized flow. CONSTITUTION:A fluidized bed 2 is partitioned by a partition plate 3 into a combustion zone 4 for igniting dust fuel and a heat recovery zone 5 for recovering heat. At the bottom part of each of the zones 4 and 5 are present an air box 6 to which fluidizing air is supplied and another air box to which the fluidized low temperature combustion gas is supplied. Within the heat recovery zone 5 is present a high temperature super- heater 8 for recovering heat. The fluidizing medium becomes a high temperature under combustion of the combustion zone 4 and the fluidizing medium of high temperature is automatically circulated to the heat recovering zone 5. With such an arrangement as above, high temperature corrosion is not produced at a heat transfer surface of the heat recovering zone and steam of high temperature and high pressure can be generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed combustion apparatus for effectively utilizing unused thermal energy contained in a refuse fuel which produces corrosive gas such as hydrogen chloride during combustion.

[0002]

2. Description of the Related Art In the combustion of refuse fuel, a high concentration of hydrogen chloride is generated due to the inclusion of vinyl chloride or the like. This hydrogen chloride causes corrosion on the heat recovery and heat transfer surfaces of the combustion gas.

In order to prevent this, conventionally, the temperature of the combustion gas is lowered by water injection or the like, and the heat recovery heat transfer surface is arranged in a low temperature range to lower the temperature of the generated steam, thereby reducing the heat transfer in the convection section. The temperature of the wall of the heat pipe was lowered to avoid high temperature corrosion (see, for example, Chemical Equipment, June 1986, P68, "Application of fluidized bed to municipal solid waste incinerator"). Therefore, the heat recovery rate is low due to the heat loss of combustion gas due to water injection and the reduction of steam conditions, and the power generation efficiency is very low, around 7%.

On the other hand, recently, in a fluidized bed boiler, a partition plate divides a combustion chamber and a heat recovery chamber, and a plurality of fluidized beds are provided so that a fluid medium can circulate between the combustion chamber and the heat recovery chamber. , A predetermined fluidized bed of a plurality of fluidized beds is a fluidized bed that burns solid fuel, and the other fluidized bed is a fluidized bed that burns waste such as municipal waste and various industrial wastes, or co-firing solid fuel and waste Heat recovery of a fluidized bed for burning waste or a fluidized bed for co-firing solid fuel and waste by placing a superheater in the fluid medium layer of the heat recovery chamber of the fluidized bed for burning solid fuel By placing an evaporator in the fluidized medium of the chamber to improve the heat recovery rate and prevent the heat transfer tubes from being corroded by the highly corrosive gas associated with the combustion of waste, a double bed with a vapor pressure suitable for the boiler load Type fluidized bed boiler has been proposed (Japanese Patent Laid-Open No. 2-290 as a prior art document). There is a 01 JP).

By the way, this multi-bed type fluidized bed boiler has a complicated structure and a large size because it is divided into a fluidized bed for burning solid fuel and a fluidized bed for burning waste or mixed burning of waste and solid fuel. In addition, since the solid fuel has to be burned to burn the waste, the extra thermal energy of the solid fuel is required to recover the unused thermal energy of the waste, which is not preferable from the viewpoint of energy saving.

[0006]

Therefore, the present invention effectively utilizes the unused thermal energy contained in the above-mentioned waste fuel which generates corrosive gas such as hydrogen chloride, without requiring the extra thermal energy of the solid fuel. In order to utilize it for the purpose of producing a high temperature and high pressure steam without causing high temperature corrosion, increasing the heat recovery rate, and improving the power generation efficiency, it is intended to provide a fluidized bed combustion device for exclusive use of refuse fuel. Is.

[0007]

A fluidized bed combustor of the present invention for solving the above-mentioned problems is a device for combusting a refuse fuel that generates a corrosive gas such as hydrogen chloride during combustion. Each of the fluidized beds, which separates the burning zone and the heat recovery zone, is provided, and the waste fuel, the fluidized medium and the fluidized air are supplied to the combustion zone so that the waste fuel is burned in the fluidized bed. Is characterized in that a heat transfer surface for heat recovery is provided, only the high temperature fluidized medium in the combustion zone is circulated, and low temperature combustion gas is supplied to fluidize and recover heat.

[0008]

In the fluidized bed combustion apparatus of the present invention configured as described above, the refuse fuel that generates corrosive gas such as hydrogen chloride, the fluidized medium and the fluidized air are supplied to the combustion zone, and the refused fuel is fluidized in the fluidized bed. Although it is burned, the waste fuel is not supplied to the heat recovery zone, only the high temperature fluidized medium in the combustion zone is circulated, and low temperature combustion gas is supplied to flow the high temperature fluidized medium to form a fluidized bed. In the unlikely event that refuse fuel that generates corrosive gas such as hydrogen chloride arrives in the heat recovery zone, it will not burn, and therefore, generation of hydrogen chloride will be suppressed.
The heat transfer surface provided in this heat recovery zone does not cause high-temperature corrosion and recovers the heat of the high-temperature fluid medium, resulting in the generation of high-temperature and high-pressure steam, increasing the heat recovery rate and enabling highly efficient power generation. Become. Further, in the fluidized bed combustion apparatus of the present invention, since only the waste fuel is burned and the excess solid fuel is not burned, the unused heat energy of the waste fuel can be effectively used without requiring the extra heat energy.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fluidized bed combustion apparatus of the present invention will be described with reference to FIG. 1. Reference numeral 1 is an apparatus body, 2 is a fluidized bed, and this fluidized bed 2 is partitioned by a partition plate 3 to burn dust fuel. It is divided into a combustion zone 4 and a heat recovery zone 5 for recovering heat. At the bottoms of the combustion zone 4 and the heat recovery zone 5, there are provided a wind box 6 to which the flow air is supplied and a wind box 7 to which the low temperature combustion gas for flow is supplied, respectively. A high temperature superheater 8 for recovering heat is provided in the heat recovery zone 5. 9 is a refuse fuel supply port, 10 is a low-temperature superheater provided in the exhaust gas duct 1a above the apparatus main body 1, and 11 is a fluid medium guide plate provided above the heat recovery zone 5.

In another embodiment shown in FIG. 2, the fluidized bed 2 is partitioned by two partition plates 3 and a large combustion zone 4 is provided in the middle.
And heat recovery zones 5 and 5 are separated on both sides, and a wind box 6 to which the flow air is supplied and a wind to which the flow exhaust gas is supplied are provided at the bottoms of the combustion zone 4 and the heat recovery zones 5 and 5, respectively. Boxes 7 and 7 are provided. Others are the same as the embodiment of FIG.

In the fluidized bed combustor of each embodiment thus constructed, the fluidized medium is supplied to the combustion zone 4 and the heat recovery zone 5 from the waste fuel supply port 9, and the combustion zone 4 is also supplied from the combustion supply port 9. A waste fuel that generates a corrosive gas such as hydrogen chloride is supplied, and the wind box 6 at the bottom of the combustion zone 4 is also supplied with flowing air to burn the waste fuel in the fluidized bed. By this combustion, a high temperature gas of 600 to 650 ° C. is generated, the fluidizing medium becomes a high temperature of 450 to 550 ° C., and the high temperature fluidizing medium naturally circulates to the heat recovery zone 5 side.
In the wind box 7 at the bottom of the heat recovery zone 5, after the heat is recovered by the low-temperature superheater 10 provided in the exhaust gas duct 1a in the upper part of the apparatus body 1, the concentration of hydrogen chloride discharged from the downstream bag filter (not shown) is shown. A low-temperature combustion gas of about 150 ° C. is supplied to flow a high-temperature fluid medium to form a fluidized bed. In this way, even if dust fuel such as corrosive gas such as hydrogen chloride is scattered on the heat recovery zone 5 side, it does not burn because there is no combustion air and the combustion gas is supplied. Therefore, the high temperature superheater 8 provided in the heat recovery zone 5 does not undergo high temperature corrosion and absorbs the heat of the high temperature fluid medium, resulting in the generation of high temperature and high pressure steam, which improves the heat recovery rate. Power generation efficiency is 1
Increased to 5-30%. In addition, since only the waste fuel is burned and excess solid fuel or the like is not burned, it is possible to effectively use the unused heat energy of the waste fuel without requiring extra heat energy.

[0012]

As described above, according to the fluidized bed combustion apparatus of the present invention, high temperature corrosion does not occur on the heat transfer surface of the heat recovery zone even when the refuse fuel that generates corrosive gas such as hydrogen chloride is burned. In addition, the heat of the high-temperature fluid medium can be recovered to generate high-temperature and high-pressure steam, so that the heat recovery rate is increased and high-efficiency power generation becomes possible. In addition, by burning the waste fuel exclusively, not only the unused heat energy of the waste fuel can be effectively utilized without requiring extra energy, but also the structure of the device can be simplified and downsized, and maintenance can be performed. Will also be easier.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a fluidized bed combustion apparatus of the present invention.

FIG. 2 is a schematic view of another embodiment of the fluidized bed combustion apparatus of the present invention.

[Explanation of symbols]

 1 Device Main Body 2 Fluidized Bed 3 Partition Plate 4 Combustion Zone 5 Heat Recovery Zone 6 Wind Box to Supply Air for Flow 7 Wind Box to Supply Low Temperature Combustion Gas for Flow 8 High Temperature Superheater 9 Waste Fuel Supply Port 10 Low Temperature Overheat Vessel 11 guide plate

Claims (1)

[Claims] 1. In a device for combusting a waste fuel that generates a corrosive gas such as hydrogen chloride during combustion, a fluidized bed is provided in which a zone for burning the waste fuel and a zone for recovering heat are provided, and a combustion zone is provided. The waste fuel, the fluid medium and the fluid air are supplied to burn the waste fuel in the fluidized bed, and the heat recovery zone is provided with a heat transfer surface for heat recovery.
A fluidized bed combustion apparatus characterized in that only the high temperature fluidized medium in the combustion zone is circulated and low temperature combustion gas is supplied to fluidize and recover heat.