JPS6150205B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a suitable medium in a method for incinerating fossil fuel ash (hereinafter referred to as "ash") in a fluidized bed furnace. Ash containing unburned carbon is discharged from boilers such as large thermal power plants that burn large amounts of fossil fuels (hereinafter referred to as "fuel"). When this ash is disposed of as waste, it is often disposed of by a specific company because its properties make it unsuitable for general landfill. However, there are many problems such as high transportation costs and troubles in handling due to the powder. For this reason, devices have been developed that reduce the volume and weight of ash by incinerating the ash as ancillary equipment for furnaces such as large boilers that are the source of the ash, thereby alleviating the above-mentioned problems. The advantage of this device is that since the vanadium compounds contained in the ash are concentrated, expensive vanadium can be recovered and its handling becomes advantageous. There are various types of incinerators for the above ash, but each has its advantages and disadvantages.
Among these, ash treatment using a fluidized bed furnace is attracting attention because it responds well to changes in load and ash composition.

However, it has been discovered that even in a fluidized bed furnace, the fluidized medium becomes thickened with deposits over time during incineration, causing poor fluidization and making long-term continuous operation difficult. For this reason, it is necessary to stop the furnace and replace the medium, which is disadvantageous in terms of workability, operating costs, medium costs, etc., and improvements in these areas are desired.

The present invention eliminates the above-mentioned drawbacks and facilitates reproduction of media.

As a result, continuous operation of the furnace is also possible. That is, according to the present invention, if a medium is continuously or discontinuously taken out from an incinerator for incinerating fossil fuel ash and a cleaning liquid is added to the medium for cleaning, dissolved components in the ash adhering to the surface of the medium are removed by the cleaning liquid. dissolve. Incidentally, since the adhesion of undissolved components of the deposits to the medium weakens, more favorable results can be obtained if they are mechanically peeled off. Further, in the present invention, at least one of the cleaning liquid (including undissolved components) and the fluidized medium can be dried with hot gas to regenerate the medium, and it is also possible to use a new medium.

Hereinafter, one embodiment of the present invention will be explained using diagrams.

Table 1 Sample components Adhering ash composition (%) Na ₂ O 16.6 SO ₃ 33.0 V ₂ O ₅ 14.0 SiO ₂ 3.6 Al ₂ O ₃ 5.0 Fe ₂ O ₃ 11.1 NiO 11.7 CaO 1.6 Table 1 shows heavy oil ash produced in a fluidized bed furnace. When incinerated,
An example of analysis of substances attached to the surface of a fluid medium is shown.
The main components are Na ₂ O ₃ and SO ₃ , but these are thought to exist in the form of sodium sulfate (Na ₂ SO ₄ ). One possible way to separate deposits of this composition from the medium is to mechanically crush them and separate the two, but this is possible by applying a force that does not crush the medium (generally sand). It is difficult to peel off the kimono, and if a force is applied to crush the adhesion, the medium itself will also be pulverized, and the original purpose of recycling the medium will not be achieved, which is impractical. This is thought to be because the deposits have higher elasticity and are stronger against impact force than the medium. Therefore,
The inventors focused on the fact that Na ₂ SO ₄ , which is thought to account for about 50% of the deposits, is water-soluble, and found that the adhesion and elasticity of the deposits sharply decrease in the presence of water. This also suggests that by washing the fluid medium with water or by applying mechanical force in the presence of water,
It was thought that washing would enable further removal of deposits. Therefore, the deposits
As a result of adding water at a weight ratio of 1:1 to a 24.5% fluid medium and crushing it in a ball mill for 10 minutes,
It was confirmed that 90% of the deposits were removed and there was almost no pulverization of the sand medium. However, this method is inconvenient for recovering vanadium and the like because the deposits are recovered as slurry, and secondary treatment is required.

Also, in order to reuse the fluid medium, it is necessary to dry it.

Therefore, it is necessary to perform both the washing process and the drying process.

In one example, a 1:1 weight ratio of water was added to a fluidized medium with 24.5% deposits, and crushing was carried out in a ball mill for 30 minutes.

At this time, heated air was blown into the ball mill from the outside through an air hole, and the evaporated water was discharged together with the heated air through a discharge hole.

As a result, 85% of the deposits were peeled off and recovered as a solid powder. Furthermore, no powdering of the sand medium was observed. FIG. 1 shows the flow of the minimum necessary equipment to carry out the present invention.

The medium is extracted from the fluidized bed furnace 1 and passed through line 11.
The liquid then enters a washing machine 2 (which may also include mechanical washing operations such as stirring using a ball mill or screw conveyor). Here, washing is carried out in the presence of a washing liquid from line 21. Next, hot gas from the fluidized bed furnace 1 is introduced into the washer 2 from the line 31, so that washing and drying are performed. The dried medium and deposits are separated in a separator 3 attached to the rear of the washer 2 and the medium is recycled via line 41 to the fluidized bed furnace 1. On the other hand, the deposit is line 5
1 and then processed. The exhaust gas containing water vapor is treated via line 61.

Next, another embodiment of the present invention will be described with reference to FIG. The medium is withdrawn from the fluidized bed furnace 1 through line 11 and enters the washer 2. Here, a cleaning action is applied in the presence of the cleaning liquid from the line 21, and hot gas from the fluidized bed furnace 1 is introduced from the exhaust gas line 31 for cleaning and drying. The dried media and deposits are introduced into the fluidized bed furnace 1 through the reclaimed sand line 41. In the fluidized bed furnace 1, the medium and powdery deposits are easily separated. In this flow,
It is possible to reuse the fluid medium without installing a separate separator. In the present invention, the soluble components in the deposits are dissolved and removed by the washing treatment of the fluid medium, and the insoluble substances remain in a porous state. Therefore, the process of mechanically peeling off substances adhering to the fluid medium may be performed simultaneously with the cleaning process, or may be performed in addition to the cleaning process. According to the present invention, it is possible to easily regenerate a fluid medium, and it is fully expected to save the labor of regeneration workers and reduce media consumption costs by regenerating the medium. Furthermore, if a portion of the medium is extracted from the fluidized bed and recycled, continuous operation of the ash incineration process is also possible. In addition, by using combustion gas from a fluidized bed furnace or combustion gas from an unburned carbon incinerator following the fluidized bed furnace as the drying gas for the cleaning liquid and/or fluidized medium, this process can be carried out without the need for special equipment. The invention can be put into practice.

[Brief explanation of the drawing]

FIG. 1 is a process flow diagram of the present invention, and FIG. 2 is a process flow diagram showing another embodiment of the present invention. Explanation of symbols, 1...Fluidized bed furnace, 2...Washing machine, 3...
Separator, 11...medium extraction line, 21...washing liquid supply line, 31...hot gas line, 41...recycled sand line, 51...deposit line, 61...exhaust gas line.

Claims (1)

[Claims] 1. The process of continuously or discontinuously extracting the fluidized medium used in an incinerator for incinerating fossil fuel ash to the outside of the bed, and the state in which the layer of material attached to the fluidized medium can be mechanically peeled off. a washing process of washing with a washing liquid until the washing process is completed; a drying process of drying at least the fluidized medium of the washing liquid and the fluidized medium after washing with hot gas; and a drying process from the washing process to the drying process. A method for regenerating a fluid medium, comprising a step of mechanically peeling off substances adhering to the fluid medium after the steps up to or after the drying step.