JPS5827312B2 - Fluidized bed equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed apparatus, and particularly to a fluidized bed apparatus used for coal gasification, coal combustion, etc.

Conventionally, petroleum-based fuels have been mainly used as fuel for power generation, raw material for city gas, fuel for general household use, and the like.

However, there is a limit to the absolute amount of oil resources, and combined with the expansion and rapid increase in demand, we are at a stage where it is predicted that there will be a shortage of oil resources in the future.

From this perspective, coal resources are once again attracting attention, and their reuse is attracting attention in various circles.

In particular, coal reserves are said to be several dozen times larger than oil reserves, so it can be said that the country is in an advantageous situation in terms of resources.

In Japan as well, there is a need to diversify the use of energy resources, and research into producing pollution-free fuel from coal is actively progressing.

In other words, it is said that the plan to produce synthetic natural gas from coal is both realistic and an easy way to obtain a large amount of clean energy.

Methods of obtaining synthetic natural gas from coal, which are currently practiced in Western countries, include hydrocracking, partial oxidation, and contact methods using basic media.

Generally, many of these methods or devices for carrying out these methods have low reaction rates, and therefore it is necessary to increase the residence time of the gas within the device.

For example, in the United States, the so-called Hygas process is currently under development, and this new method tends to utilize a hydrocracking method using multistage fluidized beds from the viewpoint of increasing residence time.

In this way, in coal gasification, it is generally necessary to keep the gas residence time around 2 to 10 seconds, and when applying a fluidized bed reactor that satisfies this condition, the height of the fluidized bed must be set particularly high. However, it is necessary to form a fluidized bed in multiple stages.

However, if the bed height is increased, slagging phenomenon tends to occur, which lowers the solid-gas contact rate and causes a decrease in the reaction rate.

Furthermore, in the case of a fluidized bed combustion apparatus, the dispersibility of the fluidized medium or coal particles becomes poor, resulting in a reduction in combustion and other reaction efficiencies.

The purpose of the present invention was made in view of the problems seen in the prior art as explained above. The purpose of the present invention is to provide an improved fluidized bed apparatus that can prevent the tendency of occurrence of the phenomenon (phenomenon) and obtain a stable fluidized state and high reaction efficiency.

The present invention provides a fluidized bed device in which a gas for fluidizing coal particles is supplied from below a dispersion plate to form a fluidized bed of coal particles on the dispersion plate. It is characterized by having a supply port for granulated coal.

More specifically, the present invention supplies gas in which pulverized coal (pulverized coal with a size of about 40 to 100 μm) is suspended as a fluidizing gas from below the fluidized bed, and The slackening phenomenon is prevented by supplying coarse coal or catalyst particles (500 to 300 μm in size) to increase the apparent density of the fluidizing gas.

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of an apparatus system showing an embodiment in which the present invention is applied to coal gasification. Coal particles to be gasified are supplied from a raw material supply system 1 into a reactor 3.

On the other hand, fine coal particles (40 to 100 microns) for fluidization are similarly supplied from the fluidization raw material supply system 2 into the reactor 3.

In the reactor 3, raw material coal particles are fluidized and gasified.

A gasifying agent for aiding and promoting gasification is supplied via a gasifying agent supply system 4.

In the reactor 3, fluidized and gasified coal particles, generated gas, etc. are sent to a cyclone 5, where they are separated into fine coal particles and generated gas.

The generated gas is further sent to a dust remover 6, where solids and the like contained in the generated gas are removed and discharged to the outside.

As described above, in the method of the present invention, the coal particles to be gasified are sent to the reactor 3 via the raw material supply system 1, and the gasifying agent sent from the above-mentioned another supply system 4 and the fine particles for fluidization Fluidized by coal particles, etc.

The fine coal particles for fluidization are much lighter in weight than the coal particles to be gasified, and the fine coal particles are entrained in the fluidizing gas.

The entrained coal particles collide with the flowing coal particles, increasing the apparent density and viscosity of the fluidizing gas, increasing the residence time of the coal particles in the fluidized bed, and improving reaction efficiency. At the same time, it has an effect similar to that of a solid-liquid fluidized bed, which is generally said to be in a stable state.

As already explained above, the unreacted fine coal particles entrained in the gas are separated by the cyclone 5, returned to the lower part of the fluidized bed in the reactor 3, and circulated within the apparatus. Become.

Although pulverized coal may be newly supplied to the lower part of the fluidized bed from outside the system, coal utilization efficiency can be improved by supplying unreacted pulverized coal (recovered char) separated by cyclone 5 as described above. will improve.

It is also possible to include pulverized coal in a fluidizing gas (gasifying agent) and supply it from below the dispersion plate.

Figure 2 shows the relationship between pressure loss ΔP in the fluidized bed and time when Yubari coal is used as the raw material coal particles and the gasification reaction is proceeded without using fluidizing particles. .

In other words, the figure shows the change in pressure loss in the fluidized bed over time when a fluidized bed is formed using air using a reactor with an inner diameter of 50mm and a height of 1000mm. As can be seen, the pressure fluctuations were extremely large, and it is thought that a uniform fluidized bed was not formed.

Figure 3 shows the relationship between pressure loss △P in the fluidized bed and its time over time when a stable fluidized bed is formed by applying fine particles for fluidization, which is a feature of the method of the present invention. It is.

As can be clearly seen by comparing Figures 3 and 2, the change in pressure loss △P in the bed over time when using fluidizing particles is extremely small, and it is thought that a stable fluidized bed is formed. .

As can be understood from the above description, according to the present invention, the apparent density of the fluidizing gas is increased by feeding pulverized coal from below the fluidized bed and coarse coal above it. This makes it possible to stabilize the fluidized bed, increase the residence time of pulverized coal, and proceed with the coal gasification reaction with high reaction efficiency without increasing the height of the fluidized bed extremely. Therefore, it is not only possible to prevent the tendency of the slagging phenomenon caused by increasing the height of the fluidized bed, but also it is possible to downsize the coal gasification apparatus.

In particular, by applying the present invention, it is possible to form a fluidized bed in only one stage, whereas conventionally it was necessary to form a fluidized bed in multiple stages.
This made it possible to sufficiently increase the reaction efficiency.

The present invention is widely applicable not only to coal gasification reactors but also to general fluidized bed reactors such as fluidized bed combustion equipment, fluidized bed cracking equipment for heavy oil, coal coke, etc.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a gasifier system that implements the method of the present invention, Figure 2 is a diagram showing the change in pressure loss in the fluidized bed over time when fine particles for fluidization are not applied, and Figure 3 is a diagram showing the change in pressure loss over time in the fluidized bed. FIG. 2 is a diagram showing a change in pressure loss in a fluidized bed over time when fine particles for fluidization are applied according to the method of the present invention. 1... Raw material supply system, 2... Raw material supply system for fluidization, 3... Reactor, 4... Gasifying agent supply system, 5. ...Cyclone, 6...Dust remover.

Claims (1)

[Claims] 1 In a fluidized bed device that supplies gas for fluidizing coal particles from below the dispersion plate to form a fluidized bed of coal particles on the dispersion plate, pulverized coal and coarse coal are placed below and above the fluidized bed, respectively. A fluidized bed device characterized by having a supply port.