JPS58678Y2 - Fluidized bed temperature control device in fluidized bed reduction process - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a temperature control device for a fluidized bed furnace that improves the means for controlling the temperature of the fluidized bed in a fluidized bed reduction process.

Generally, a fluidized bed iron ore reduction process using coal results in the fluidized bed temperature being lower than the blowing gas temperature due to coal gasification and iron reduction reactions and ore heating within the fluidized bed.

Therefore, conventionally, a gas preheater is used as a means for raising the temperature of the fluidizing gas in the fluidized bed, or electrodes are provided in the fluidized bed to maintain the fluidized bed at the required temperature using Joule heat. In the case of , the structure becomes complicated and the design difficulty increases, resulting in an increase in cost.On the other hand, in the case of the latter electrode,
There has been a major problem in the use of electricity in areas such as remote areas where electricity is not abundant.

In addition, as a means different from any of the above cases, C+ 02 is produced by blowing oxygen or air into the fluidized bed.
It is also possible to raise the temperature of the fluidized bed by the reaction of →CO2 and 2C+02→2CO, but in this case, in addition to the above reaction, it is also possible to react with CO or H2 in the fluidized bed to dilute the reducing component and slow down the reduction rate. If the blowing medium is oxygen or air, there is a risk that the oxygen will promote re-oxidation of the reduced iron.

Furthermore, all of the above-mentioned means have not been able to satisfy energy saving as a whole.

This idea was made to solve the various problems mentioned above,
The purpose is to smoothly and efficiently supply replenishment heat to the fluidized bed, which already has convective heat transfer due to the fluidization phenomenon, without changing the atmosphere in the fluidized bed reduction process, without requiring a high-temperature gas preheater or electricity. Provided is a temperature control device for a fluidized bed furnace, which has a configuration that can increase the temperature of the fluidized bed, promote energy conservation, and reduce costs, and can also be adapted to cooling the furnace walls, etc. It's about doing.

An embodiment of this invention will be described below with reference to FIGS. 1 to 3.

In Fig. 1, reference numeral 1 is a fluidized bed type reduction furnace in the form of a vertical tube with a funnel-shaped bottom. It is formed by lining and has a reduced iron extraction port 4 at the bottom of the furnace.

Further, the reduction furnace 1 has a porous rectifying plate 5 provided inside the upper side of the funnel-shaped part, and an ore hopper 6 and a coal powder hopper 7 for feeding raw materials, which are opened and communicated with the top of the furnace. , and a gas blowing pipe 8 is installed below the center of the current plate 5.
The tip is open, so that a fluidized bed 9 is formed above the rectifying plate 5 in the furnace.

In the reduction furnace 1, a heat medium flow path 10 is provided inside the furnace along a portion where a fluidized bed 9 is formed.

In this embodiment, the heat medium flow path 10 is composed of a plurality of radiant tubes, and these radiant tubes are arranged along the formation part of the fluidized bed 9 as described above, and surround the fluidized bed 9 as shown in FIG. Outwardly bent portions 1 are arranged in an annular arrangement at regular intervals and bent at the upper and lower ends of each
0 a and 10 b are closely penetrated through the furnace wall and led out of the furnace.

As shown in FIG. 3, the nozzle tip is inserted into the lower side of each of the radiant tubes forming such a heat medium flow path 10 from the open end of each lower bent part 10b, and the nozzle tip is exposed inside the vertical part of the tube. A burner 11 is provided.

Each burner 11 forms a secondary air passage 12 for blowing combustion air between it and the radiant tube wall, and the burner 11 has its own nozzle connected to an intake port 13 opened at an extension outside the radiant tube. It has a primary air passage 14 that opens at the tip.

In the reduction furnace 1 having the above structure, a waste gas pipe 15 is connected to the top of the furnace, and this waste gas pipe 15 communicates with a cyclone 16.

The cyclone 16 communicates with a gas cooler 18 via a gas pipe 17, and the gas cooler 18 communicates with a gas heater 20 via a fuel gas pipe 19, respectively.

The fuel gas pipe 19 communicates with a blower 22 via a branch pipe 21, and this blower 22 is connected to a desulfurizer 24 and a desulfurizer 24.
They are sequentially connected to an O2 container 26 via gas pipes 23 and 25, respectively.

The CO2 remover 26 is connected to the gas heater 20 through a gas pipe 27, and the gas heater 20 is connected to the gas blowing pipe 8.

The gas pipe 23 that communicates between the blower 22 and the desulfurizer 24 has a branch gas pipe 28 in the middle.
is in communication with each burner 11 of the heat medium flow path 10.

Next, the operation of the above embodiment will be explained.

First, by charging ore and coal powder into the reduction furnace 1 from each of the ore hopper 6 and the coal powder hopper 7, the rectifying plate 5 in the reduction furnace 1 is
A fluidized bed 9 is formed in the upper layer.

In this state, by blowing out reducing gas from the gas blowing pipe 8, the reducing gas heats the fluidized bed 9 and promotes the gasification reaction of the coal powder and the reduction reaction of the ore forming the bed.

On the other hand, the waste gas discharged from the top of the reduction furnace 1 is passed through the waste gas pipe 15, the cyclone 16, the gas pipe 17, and the gas cooler 1.
8, and the gas cooler 18, the waste gas passes through a gas pipe 19 to a gas heater 20, and from a branch pipe 21 of the gas pipe 19 to a blower 22, a gas pipe 23, a desulfurizer 24, and a gas pipe 25. , the CO2 remover 26 , and the gas pipe 27 to follow the thread path toward the gas heater 20 and the branch gas pipe 28 to follow the thread path toward the burner 11 in the heat medium flow path 10 .

The dust-free and pressurized waste gas that has flowed into the burner 11 is sucked in from the intake port 13 of the burner 11 and passes through the primary air passage 14 together with the primary air from the nozzle tip of the burner 11 to the heat medium passage, that is, the radiant tube 10. By being injected as fuel into the vertical portion, it becomes a combustion flame 29 shown in FIG. 3, which heats the radiant tube 10 from the inside.

Therefore, the temperature of the radiant tube 10 is 900 to 1000°C.
Due to the heat dissipation phenomenon from the peripheral wall of the radiant tube 10, the fluidized particles, which already have convective heat transfer due to the flow phenomenon of the fluidized bed 9, are further heated. As a result, the fluidized bed 9 is heated to a temperature state suitable for promoting reaction (reduction) within the bed.

In the embodiment described above, the heat medium flow path 10 has a fourth
As shown in the figure, a double array structure may be used in which a plurality of radiant tubes are not only arranged in a ring along the periphery of the fluidized bed 9 as described above, but also arranged in a ring inside the fluidized bed 9. In this case, the temperature of the fluidized bed 9 can be further promoted to accelerate the reduction rate of the fluidized particles.

In addition, when the reduction furnace 1 has a rectangular tube shape with a rectangular cross section as shown in FIG. It is preferable to use a structure in which radiant tubes are arranged at predetermined intervals.

Furthermore, the radiant tube for the heat medium flow path 10 is
As shown in FIG. 6, a straight tube type may be used. In this case, the furnace wall of the reduction furnace 1, which serves as the radiant tube mounting wall, is bulged outward, and the upper and lower walls of the furnace wall bulge 1a are The straight radiant tube may be freely inserted and removed through the radiant tube, and the radiant tube can be easily replaced with a new one at any time.

The above are various modification examples in which the heat medium flow path 10 is composed of a plurality of radiant tubes.
may be integrally formed using the furnace wall of the reduction furnace 1, and the configuration in that case will be explained below based on FIGS. 7 and 8.

That is, in this embodiment, the reduction furnace 1 includes a fluidized bed 9
The surrounding furnace wall is integrally formed as an annular expansion furnace wall 30 that bulges outward in the radial direction, and the inner open end thereof is formed by a heat exchange wall 31 made of a refractory material such as silicon carbide along the periphery of the forming part of the fluidized bed 9. By integrally closing the annular expansion furnace wall 30, the inside of the annular expansion furnace wall 30 is used as a heat medium flow path 10.

Further, the annular expansion furnace wall 30 has a combustion waste gas outlet 33 on its upper side and a plurality of burner ports 34 on its bottom.
are provided at predetermined intervals.

A burner 11a is attached to each burner port 34, and the burner 11a has the same structure as that of the previous embodiment shown in FIG. 3, except that it is vertical.

With the above configuration, the first
This is because the dust-free and pressurized waste gas guided to the burner 11 following a circulation path similar to the flow sheet shown in the figure is ejected from the burner 11 into the heat medium flow path 10 and becomes a thermal sintering flame. The heat exchange wall 31 is heated, and due to the heat radiation phenomenon from the heat exchange wall 31, the fluidized particles in the fluidized bed 9 are heated to a high temperature as in the previous embodiment.

In each of the above embodiments, only the case where the fluidized bed 9 is heated by the heat medium flow path 10 using waste gas from the reduction furnace 1 has been described, but the combustion fuel supplied into the heat medium flow path 10 is Of course, other fuels than gas may also be used.

Further, the heat medium flow path 10 can be adapted not only for heating the fluidized bed 9 to a high temperature but also for cooling the furnace wall of the reduction furnace 1. In that case, a circulating refrigerant is provided in the heat medium flow path 10. Just let it pass.

Furthermore, this invention can be implemented in furnaces other than the reduction furnace 1.

As explained above, in this device, a heat medium flow path is provided along the fluidized bed forming part in the furnace, and the heat medium is supplied into the path. By doing so, the heat dissipation phenomenon from the heat medium flow path can further provide supplementary heat to the fluidized bed that already has convective heat transfer, and therefore the fluidized bed can be quickly heated to the required temperature. can be converted into

Moreover, waste gas from the top of the furnace can be used as the fuel for the heating medium, and no electric power is required, so a great effect can be obtained that contributes to energy saving.

In this way, in this invention, supplementary heat is given to the fluidized bed by the heat dissipation phenomenon from the heat medium flow path, and other foreign substances contained in the heat medium are not brought into the fluidized bed. Supplementary heat can be smoothly supplied to the fluidized bed without changing the internal atmosphere.

In addition, as mentioned above, this device has a simple configuration and does not require a high-temperature gas preheater like conventional ones, so it is possible to reduce costs, and because it does not require electricity, it can be used in remote areas where electricity is insufficient. It is extremely effective when implemented locally.

Furthermore, in this invention, by supplying a cold medium as a heat medium into the heat medium flow path, it is also possible to cool the furnace wall, etc.

[Brief explanation of drawings]

Fig. 1 is a schematic longitudinal sectional view of a fluidized bed reduction furnace including a flow sheet according to an embodiment of this invention, Fig. 2 is an enlarged cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 4 and 5 are cross-sectional views showing different arrangement configurations of the heat medium flow path, and FIG. 6 shows a modification of the heat medium flow path attachment means. 7 is a longitudinal cross-sectional view showing a further modification of the heat medium flow path, and FIG. 8 is a cross-sectional view taken along the line ■--■ in FIG. 7. In the figure, 1 is a fluidized bed furnace, 9 is a fluidized bed, and 10 is a heat medium flow path.

Claims (1)

[Scope of utility model registration request] In a fluidized bed reduction process in which iron ore and coal are reduced by forming a fluidized bed with a reducing gas, a heat medium flow path is provided in the fluidized bed forming section, and the heat medium obtained from the fluidized bed is provided in the flow path. A temperature control device for a fluidized bed in a fluidized bed reduction process, characterized in that a burner is provided for controlling temperature by burning fuel gas including process circulating gas and variably transmitting heat to the fluidized bed.