JPH013038A - Method for producing solidified material using fluidized bed combustion ash as raw material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to coal ash (coal ash content and Made from used desulfurizing agent), it has a high bulk density and no particles stick to each other.
The present invention relates to a method for producing high-strength granules in a short time.

[Conventional technology]

Conventionally, pulverized coal combustion has been the main combustion method when coal is used as fuel, but fluidized bed combustion has recently been attracting attention. This fluidized bed combustion method usually employs an in-furnace desulfurization method, in which coal as a fuel and limestone as a desulfurizing agent for in-furnace desulfurization are input to form a fluidized bed in a boiler. Compared to the conventional pulverized coal combustion method, the fluidized bed combustion method has the following advantages: firstly, the furnace volume is smaller and the boiler volume is smaller; secondly, there are fewer restrictions regarding the type of fuel coal; and thirdly, the fuel coal type is less restricted. It has the advantages of being able to burn at a low temperature of .degree. C., causing no troubles related to ash condensation, and generating little thermal No.chi., and fourthly, having a large overall heat transfer coefficient on the surface of the heat transfer water tube. On the other hand, there is a problem with ash disposal in the practical application of fluidized bed combustion technology. Coal ash generated during fluidized bed combustion is composed of coal ash and spent desulfurization agent, and the spent desulfurization agent is composed of the desulfurization product, Type 1 water gypsum, and unreacted quicklime.

In order to increase the removal efficiency of sulfur oxides in coal combustion gas, that is, the desulfurization rate, the amount of limestone input is usually set so that the Ca/S molar ratio is 3 to 6, and 750 to 750.
By reaction with sulfur oxides at 850°C, limestone becomes quicklime and type 2 water gypsum, which are discharged together with coal ash. The amount of fluidized bed combustion ash generated varies considerably depending on the type of coal used, desulfurization rate, boiler operating conditions, etc., but normally, the amount of coal ash, type water gypsum, and quicklime generated is approximately 15% of the amount of coal used. ~20% by weight, 1-10% by weight,
The ratio is 1 to 10%. - The conventional disposal and utilization technologies for such ash are as follows.

fil A humidification disposal method in which 10 to 40 parts by weight of water is added at once to 100 parts by weight of ash, heated and kneaded, and then disposed of.

(2) A humidified granulation disposal method in which 20 to 50 parts by weight of water is added at one time to 100 parts by weight of ash, kneaded to form granules, and then disposed of.

(3) A humidified granulation steam treatment method in which 20 to 50 parts of water is kneaded in two parts to 100 parts of abrasive ash to form granules, which are then treated under normal pressure steam at 60 to 100°C.

[Problem that the invention seeks to solve]

However, in the humidified disposal method described above (11), the particle size of the kneaded material is 0.01 to 100 m and it is not sufficiently compacted, so the bulk density is small and the loading capacity on transportation trucks, ships, etc. is small. , and has the disadvantage that the density and ground strength after reclamation are low.

In addition, in the humidified granulation disposal method (2) above, the particle size is 0.5 to 5.
Although it is a well-compacted granular material at 0 m, it has the following disadvantages.

(5) Due to the influence of water on the surface of the granules, the granules adhere to each other, resulting in poor handling.

Since there are almost no granules with fbl 0.5 f1 or less,
The density of the kneaded material is not significantly improved compared to the humidification method.

tel Because it is left at room temperature, the hydration reaction rate is slow.
The solidified material strength has not been sufficiently improved, and the supporting capacity of the solidified material ground is low.

+d+ Since water is added once and kneaded, if the quicklime content exceeds 7.5% by weight, the granules will be destroyed by the heat of digestion of the quicklime.

Furthermore, the humidified granulation steam treatment method (3) above has the following disadvantages.

(al) Due to the influence of water on the surface of the granules, the granules adhere to each other, resulting in poor handling.

fb) Since there are almost no granules smaller than 0.5 ur,
The density of the kneaded material is not significantly improved compared to the humidification method.

Since the strength of the granules is increased by using atmospheric pressure steam at +0160 to 100°C, the manufacturing cost becomes high.

The present invention was made in view of the above points, and by kneading coal ash and water to make it into granules, and then sprinkling it with quicklime-containing coal ash, the particle size distribution is optimized to improve transportation efficiency and landfill efficiency. In addition, by utilizing the reactivity of the sprinkled coal ash, the surface water of the granules is reacted and fixed, and the strength of the granules is quickly increased by heat generation, which prevents the granules from adhering to each other. The purpose of the present invention is to provide a method for producing a solidified product that can be produced.

[Means and effects for solving the problem] No. 1 of the present application
The method for producing a solidified material using fluidized bed combustion ash as a raw material according to the invention involves adding water once to coal ash generated during fluidized bed combustion, which is composed of coal as a fuel and limestone as a desulfurizing agent. Or, add it in multiple batches and knead to obtain a particle size of 0.5~
After making the granules mainly composed of 50 dragons, the quicklime content was 7.
It is characterized in that 5 to 20 parts by weight of coal ash is mixed in an amount of 5 to 40 parts by weight with respect to 100 parts by weight of the granules.

Further, the method for producing a solidified material using fluidized bed combustion ash as a raw material according to the second invention of the present application is applicable to coal ash generated during fluidized bed combustion consisting of coal as a fuel and limestone as a desulfurizing agent. , after adding water once or in multiple portions and kneading to form granules mainly having a particle size of 0.5 to 5 Qmm,
Quicklime content 7.5-40 by adding quicklime powder to coal ash
The method is characterized in that 5 to 20 parts by weight of the granulated material is mixed with 100 parts by weight of the granular material.

By mixing 5 to 20 parts by weight of coal ash or powder to 100 parts by weight of granules mainly having a particle size of 05 to 50 m1, fine powder (coal ash or powder) enters between the granules, Bulk density is increased, resulting in improved transport efficiency and landfill density.

In this case, if the amount of coal ash is less than 5 parts by weight, the bulk density will not improve due to the small amount of fine powder, while if it exceeds 20 parts by weight,
The bulk density decreases due to the large amount of fine powder.

In addition, if the particle size of the granules is less than 0.5 mm, the bridging ratio of the granules increases and the bulk density does not increase; on the other hand, if the particle size exceeds 50 mm, fine powder mixed in the gaps between the granules does not penetrate sufficiently, so the bulk density does not increase.

In addition, by mixing 5 to 20 parts by weight of coal ash or powder with a quicklime content of 7.5 to 40% by weight to 100 parts by weight of granules mainly having a particle size of 0.5 to 50% by weight, The water on the surface of the granules is absorbed by the mixed coal ash or powder to prevent the granules from adhering to each other and improve handling. Note that if the quicklime content in the mixed coal ash or powder is less than 7.5% by weight, water absorption will be insufficient and granules will adhere to each other. On the other hand, when the quicklime content exceeds 40% by weight, the ambient temperature rises, much water evaporates, and the solidification reaction is inhibited, resulting in poor handling properties.

If the quicklime content in the coal ash or powder is less than 7.5% by weight, the granules will not be destroyed even if water is added all at once.

However, if the quicklime content is 7.5% by weight or more, if water is added at once, the granules will be destroyed.
After adding 30 parts by weight of water and humidifying and kneading to digest most of the quicklime, 15 to 45 parts of water are further added to form granules. In this way, destruction of the granules due to the heat of digestion of quicklime is prevented.

When coal ash and water are kneaded, the following exothermic reaction occurs.

(al Quicklime - Slaked lime (digestion reaction) (bl Coal ash + Quicklime + Anhydrous gypsum monosolidified body Ettringite is the main strength member. In order to take advantage of these characteristics, when coal ash or powder is mixed with granules, the granules The surface water of the coal ash or powder transfers to the coal ash or powder, and the coal ash or powder gradually generates heat.As a result, the area around the granules has high humidity and becomes above room temperature, improving strength even without a steam treatment process.Mixing The PJ strength can be improved by controlling the heat generation rate and calorific value by adjusting the quicklime content, particle size, and presentation of the coal ash or powder. When the amount of quicklime is 7.5% by weight, the calorific value is insufficient, so it is necessary to add quicklime powder to make it over 7.5% by weight.Also, if the quicklime content is 40% by weight, If the amount of heat is exceeded, the calorific value will increase, a lot of water will evaporate, and the water necessary for the hydration reaction of the granules will be insufficient.Therefore, depending on the heat released from the kneader and granule storage hopper, By adjusting the heat generation rate by changing the amount, particle size, and mixing amount, higher strength can be expected.

〔Example] Next, examples and comparative examples of the present invention will be described.

Table 1 shows the properties of the test ash.

According to the asphalt pavement guidelines in Table 1, the modified CBR is
A 1210 (Soil compaction test method by compaction)
According to JIS A, this CBR is equivalent to a compaction degree of 95% of the maximum dry density when divided into three layers in the vertical direction and compacted 92 times each JW.
1211 (subgrade soil bearing capacity ratio test method), diameter 5
It is given by the following formula from the penetration resistance of the penetration rod of c+a.

Since the granules have hydraulic properties, they were not immersed in water for 4 days, and C[lR was measured immediately after compaction. The bulk density of the granules is 1k in a cylindrical container with an inner diameter of 250fi and a height of 410mm.
After adding granules in units of +r to make it full, the calculation was performed using the following formula.

The crushing strength was measured using a Yoneya type hardness meter using granules with a particle size of 10 m. Note that all "parts" in Examples and Comparative Examples are "parts by weight."

Example 1 10 parts of water was added to 100 parts of ash A and kneaded for 10 minutes, then 20 parts of water was further added and mixed for 3 minutes until the particle size was 0.5.
The mixture was made into granules of ~50 μl fat, and 15 parts of ash A was further added, mixed for 1 minute, and discharged from the kneader. The discharged granules were placed in a cylindrical container with an inner diameter of 250 mm and a height of 410 mm, and various tests were conducted one day later. The results were as shown in Table 2.

Example 2 After adding 2 parts of water to 820 parts of ash and kneading for 5 minutes, ash A
100 parts of the mixture was added, and further 10 parts of water were added and kneaded for 10 minutes. Further, 20 parts of water was added, and the mixture was kneaded for 3 minutes to form granules having a particle size of 0.5 to 5011. Furthermore, 15 parts of ash A was added, mixed for 1 minute, and discharged from the kneader. The discharged granules have an inner diameter of 250 fl and a height of 41 f).
It was put into a cylindrical container of I, and various tests were conducted one day later.

The results are shown in Table 2.

Example 3 10 parts of water was added to 100 parts of ash A and kneaded for 10 minutes, then 20 parts of water was further added and kneaded for 3 minutes until the particle size was 0.
5 to 50 m of granules, and further add 10 parts of ash A and 1
0 parts of Ash B was added, mixed for 1 minute and discharged from the kneader. The discharged granules were placed in a cylindrical container with an inner diameter of 250mm and a height of 410mm, and various tests were conducted one day later. The results were as shown in Table 2.

Example 4 15 parts of water was added to 80 parts of ash A and 20 parts of ash B, and after kneading for 15 minutes, 20 parts of water was further added and kneaded for 3 minutes to form granules with a particle size of 0.5 to 50 mm. Furthermore, 1
2 parts of ash A and 3 parts of ash B were added, mixed for 1 minute and discharged from the kneader. The discharged granules were placed in a cylindrical container with an inner diameter of 250 μm and a height of 410 μm, and various tests were conducted one day later. The results were as shown in Table 2.

Example 5 30 parts of water was added to 100 parts of ash C, kneaded for 3 minutes to form granules with a particle size of 0.5 to 50 carbonate, and then a mixed powder of 12 parts of ash C and 3 parts of quicklime powder was added. Additionally, the mixture was mixed for 1 minute and discharged from the kneader. The discharged granules have an inner diameter of 250 mm.
1. It was put into a cylindrical container with a height of 410 fl, and various tests were conducted one day later. The results were as shown in Table 2.

Comparative Example 1 20 parts of water was added to 100 parts of ash A, kneaded for 2 minutes, and discharged from the kneader. The discharged kneaded material was made into an inner diameter of 250mm,
It was placed in a cylindrical container with a height of 41 bm, and various tests were conducted one day later. The results are shown in Table 2.

Comparative Example 2 After adding 20 parts of water to 100 parts of ash A and kneading for 10 minutes, further adding 20 parts of water and kneading for 3 minutes to obtain a particle size of 0.5~
It was made into granules of 50 m diameter and discharged from the kneader. The discharged granules were placed in a cylindrical container with an inner diameter of 2501 cm and a height of 410 parts m, and various tests were conducted one day later. The result is second
It was as shown in the table.

(The following is a blank space) Table 2 [Effects of the Invention] As explained below, in the method of the present invention, granules with a particle size of 0.5 to 50 cm are mixed with coal ash or powder. , the bulk density increases, which improves transportation efficiency, extends the life of the landfill, and prevents granules from adhering to each other, improving handling.

In addition, since coal ash or powder containing 7.5 to 40% quicklime is used as the mixed ash, it generates heat when it comes into contact with water, and has the effect of making the granules high strength without the need for a steam treatment process. play.

Furthermore, when adding 7.5 to 40% lime by weight to coal ash, if it is kneaded with a certain amount of water in advance, the destruction of the granules due to the digestive reaction of quicklime can be prevented, resulting in high-strength granules. be able to.

Therefore, the method of the present invention is useful in the fields of highly efficient transportation and reclamation technology, and the solidified material produced by the method of the present invention is useful as civil engineering materials such as reclaim materials and backfill materials.

Sender: Kawasaki Heavy Industries, Ltd.

Claims (1)

[Claims] 1. For coal ash generated during fluidized bed combustion consisting of coal as a fuel and limestone as a desulfurizing agent,
Add water once or in multiple portions and knead to obtain a particle size of 0.5.
A fluidized bed characterized in that after forming granules mainly having a size of ~50 mm, 5 to 20 parts by weight of coal ash having a quicklime content of 7.5 to 40% by weight is mixed with 100 parts by weight of the granules. A method for producing solidified material using combustion ash as a raw material. 2. For coal ash generated during fluidized bed combustion consisting of coal as a fuel and limestone as a desulfurization agent,
Add water once or in multiple portions and knead to obtain a particle size of 0.5.
After forming granules mainly having a size of ~50 mm, add quicklime powder to coal ash to give a quicklime content of 7.5 to 40% by weight.
A method for producing a solidified material using fluidized bed combustion ash as a raw material, characterized by mixing parts by weight.