JPS6186460A - Manufacture of hardened body from fluidized bed incinerationash as main 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 Field of Industrial Application The present invention consists of coal ash generated during fluidized bed combustion in a fluidized bed consisting of coal as a fuel and limestone as a desulfurizing agent and spent desulfurizing agent. A method of producing a granular hardened body using a mixed powder as the main raw material, specifically, using the above mixed powder as the main raw material, adding water to the mixed powder that is more than the plastic limit of the mixed powder and less than the liquid limit. The present invention relates to a method for producing a hardened granular material with high mechanical strength by stirring the grains and then curing them (specifically, after curing them in a humid air, treating them with steam).

Conventional technology In recent years, in Japan, due to the international oil supply instability since the oil crisis of 1973, a large number of oil import roads have become difficult to secure, and there has been an increase in the availability of oil to reduce the dependence on oil in the energy supply and demand situation. The development of alternative energy has become a national issue, and coal energy has been highlighted as one of the pillars of energy.

Conventionally, the combustion method used when twisting coal has been the pulverized coal method, but recently the fluidized bed combustion method has gained attention. In this fluidized bed combustion method, an in-furnace desulfurization method is usually adopted, and the coal used as fuel and the desulfurized Ai for in-furnace desulfurization are used.
This is a method in which a fluidized bed is formed in the boiler by charging 1.5 liters of limestone into the boiler. Compared to the conventional powder 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; Low-temperature combustion of 850°C is possible, and there is no problem with ash condensation, resulting in thermal NO.
It has advantages such as less generation of x and fourthly, overall heat build-up on the surface of the heat transfer water tube (large number of threads).

On the other hand, there is a problem with ash disposal in the practical application of fluidized bed combustion technology. The ash generated during Flow 1.1 combustion consists of so-called coal ash and 1.U spent desulfurization agent, and the spent desulfurization agent is composed of type II gypsum, which is a desulfurization product, and unreacted quicklime. ing. In order to increase the removal efficiency of 1m1C yellow oxide 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 the amount of limestone is set at 750 to 850°. The reaction with sulfur oxides in C turns limestone into quicklime and anhydrous 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, anhydrite, and quicklime generated is the same as the amount of coal used. ! 1
5 to 20% by weight, 1 to 10% by weight, and 1 to 10% by weight.

Problems that the invention aims to solve Traditionally, most of the coal ash generated in Japan was pulverized ash,
Approximately 10 to 20% by weight of the waste was reused as fly-water as a cement admixture and as a raw material for cement, and the rest was disposed of in landfills. However, the current situation is that it cannot be expected that anything will be able to adequately deal with the generation of coal ash since 4J, either by reusing it as a raw material for cement or disposing of it in a landfill. In this way, the processing methods for coal ash and α ash have been changing to 11 for a long time, and fluidized bed combustion ash is also being treated by fluidized bed combustion at coal input sources. Considering that an extremely large amount of fluidized bed combustion ash is generated during full-scale coal combustion, establishing a unique disposal method for fluidized bed combustion ash is extremely important for the practical application of fluidized bed combustion technology. It has become a challenge. In addition, in order to establish a mass disposal method for fluidized bed combustion ash, it is essential to effectively reprint it as a resource. This is based, firstly, on the fact that in Japan, where domestically produced resources are scarce, repo-11 use, rather than mere disposal, directly leads to resource and energy conservation, and secondly, there is very little environmental destruction.

In view of the above points, the present invention aims to utilize fluidized bed combustion ash as a resource in the civil engineering field.
This was done with the aim of producing a granular hardened material with high mechanical strength by using the complete ash as Ulua (4).

Means and Function for Solving the Problems The method for producing a hardened body using fluidized bed combustion ash as a main raw material according to the present invention is based on fluidized bed combustion in a fluidized bed consisting of coal as a fuel and limestone as a desulfurizing agent. The coal ash and spent desulfurization agent generated during the process contain 60 to 85% by weight of coal ash and 10 to 10% of lime.
Quicklime and/or slaked lime, and anhydrous gypsum, hemihydrate gypsum or/and dihydrate gypsum are added as necessary to make a mixed powder with a blending ratio of 25% by weight and gypsum content of 5 to 25% by weight. In the method of adjusting the powder mixture, adding water to the mixed powder, kneading it, and then curing it, adding water that is more than the plastic limit of the mixed powder and less than the liquid limit of the mixed powder and stirring, Particle size 40 or more O weight%, particle size 2
0 or less 70-100% by weight, particle size 10 or less 50-1
00% by weight, particle size 5' or less 30-100% by weight, particle size 1 or less 5-50% by weight, particle size 0.1 or less 10% by weight
It is subjected to crushing treatment to form a kneaded product having the following particle size distribution.

After forming a kneaded material with a predetermined deviation of 1 degree, usually,
The mixture is incubated for 5 to 25 hours at room temperature to 60° C. and a relative humidity of 30% or higher, and further treated with normal pressure steam at 65 to 90° C. and 111 A of relative humidity. In addition, areas that have undergone steam treatment,
IQ: IQ: 11.

Hereinafter, the preparation of the present invention will be explained in detail. In general, the typical properties of fluidized bed combustion ash are as follows:
At first glance, it becomes a big baby. First of all, the five major nori, 'u a
! 5102, A1□03, which is a combustion residue depending on the location.
The blending ratio of components such as Ca, OSF e 203, Na 20, K2O, etc. differs, and secondly, the sulfur content in the coal is a desulfurization product... mold side water gypsum and unreacted desulfurization agent quicklime. The content is different. For this reason, when producing high-strength lattice-like hard bodies by steam treatment using fluidized bed combustion ash as the main raw material, the appropriate manufacturing conditions for granular hardened bodies depend on the composition of the fluidized bed combustion ash. different. The main manufacturing conditions are the amount of quicklime and/or water gypsum added when necessary, mixing with water to achieve an appropriate particle size distribution, wet air conditions, and steam. These include processing conditions (temperature, time), etc.

,'7. The relationship between the production conditions of the granular hardened material and the properties of the granular hardened material, which are the main principle of E-Movement 14 twisted burning ash, is summarized in the following 5.
City 9. The main component of the granular Ihi body produced by steam treatment is ettringite (3CaO-A1203.3
CaS○.

-32H20), and various forms of calcium silicate hydrate (XCaOHYSi○2'-ZH20), but the one that contributes the most to strength is ettringite. First, when the content of active water gypsum and/or quicklime content in the raw material mixed powder is low, calcium monosulfur-A1203-CaSO4.12H20) becomes the main component, and the strength of the granular f1 Although it is small, as the anhydrous gypsum content and/or quicklime content increases, the amount of ringite increases and the luminosity of the granular hardened material also increases. In addition ■degree anhydrous gypsum and/
Alternatively, when the quicklime content increases, free gypsum and/or slaked lime that does not participate in the reaction occurs during steam treatment, resulting in a decrease in the strength of the granular hardened product. The optimum composition of ingredients that maximizes the mechanical strength of the granular hardened material obtained by steam treatment is 60 to 8% coal ash other than quicklime and anhydrous gypsum.
5% by weight, quicklime content 10-25%, type 11]; Karasui gypsum 5-25% by weight. 'L lime γ and/
Or ■ degree anhydrous gypsum content is optimal [戊・fr When it is less than the quota, quicklime content and 7/or ll 4Q,
Addition of ijjE water gypsum is required.

Slaked lime may be used in place of quicklime in the case of slipping, and hemihydrate gypsum and/or dihydrate gypsum may be used in place of 11-type anhydrous gypsum. If the blending ratio of slaked lime exceeds 304% by weight, a large amount of slaked lime will remain after steam treatment, and in a dry atmosphere, the slaked lime will turn into calcium carbonate, and the initial reaction expansion will cause many hair cracks (microcracks). and product quality deteriorates.

On the other hand, crosstalk conditions also have a large influence on the properties of the granular hardened material.If the added water is less than the plasticity limit of the mixed powder, high strength will not be developed.This is due to fluidized bed combustion ash (7). Solution reaction (through
This is because the hydration reaction does not proceed sufficiently unless there is sufficient pore water. The added water is 1fi,L
If the amount exceeds the limit, the granulated particles will be crushed, making it difficult to obtain granules having a 1] IJ grain size distribution, and
This will impede transportation. Further, even if the amount of water added is appropriate, if the type of stirrer and operating conditions are not appropriate, granules having the above particle size distribution cannot be obtained. For this reason, the granular hardened body is made to have high strength,
In addition, in order to stably mass-produce granular hardened materials with appropriate particle size on an industrial scale, the amount of added water must be greater than the plasticity limit of the mixed powder, less than the liquidity limit, and the amount of water added must be greater than the plasticity limit of the mixed powder, and the amount of water added must be adjusted to suit the mixing and operation of the stirring powder. Conditions must be suitable.

The main factors for curing conditions are curing temperature and curing time. The curing process allows the hydration reaction to proceed slowly, and the
The purpose is to have an appropriate strength that can withstand the water utilization reaction expansion during steam treatment of C, and to create a high-strength granular hardened body by steam treatment. In other words, if the curing temperature is low or the curing time is short, the strength of the cured product after curing will be low, and 65~
Many cracks occur due to the steam treatment at 90°C, and the strength of the cured product decreases. On the other hand, if the curing temperature is too high, cracks will occur during curing, and if the curing time is not long, the amount of thick crystals will increase, and the amount of slag and missing raw and single-bred products produced by steam treatment will decrease. In both cases, the granular cured product 1. The malleability decreases. Furthermore, if the humidity relative to the F eye is as low as 30%, the water becomes 4 elements and the water-1 reaction does not proceed sufficiently.

For this reason, is it always necessary to produce high-strength granular hardened bodies? AN
It is best to cure the material for 5 to 25 hours at ~60'C (preferably 35 to 60'C) and a humidity of 30% or higher.Also, by increasing the curing temperature, high-strength hardened materials can be cured. The curing time for the cured product can be significantly shortened, and the process for industrial large-scale production of cured products can be significantly streamlined.

In the method of the present invention, in order for the kneaded material to develop high strength by steam treatment, the particle size should be 0% by weight of 4oIIM or more, 70-100% by weight of particle size of 20 or less, and 50-100% by weight of particle size of 10U or less.
100% by weight, grains (15MM or less 30-10% by weight,
Grain size: 1 to 1 mm or less 5 to 50% Weight: 0.1 mm or less to 10
It is necessary to filter the distribution of If, 7% by weight or less.

Water-JW 5 processing conditions are mainly processing temperature and processing time. Generally, when the steam treatment time is short or the steam treatment temperature is low, the hydrated monobenzene is composed of a mixture of calcium monosulfoaluminate and ettringite and has low strength.
water. @As the steam treatment time becomes longer or the steam treatment temperature becomes higher, the amount of ettringite produced increases and the strength also increases. If steam treatment is carried out for a long time or if the steam treatment temperature is too high, ettringite lacks heat resistance, so the generated ettringite will decompose into anhydrous gypsum and calcium aluminate hydrate, and the strength of the granular hardened product will decrease. do.

Appropriate steam treatment conditions vary depending on the hydration reactivity of the combustion ash, etc. For fluidized bed combustion ash, high-strength granular hardened material can be obtained by treating the fluidized bed combustion ash with atmospheric pressure steam at a temperature of 65 to 90'C for 5 to 15 hours. can get.

Note that as the steam treatment temperature increases, the steam treatment time becomes shorter and a high-strength granular hardened product can be obtained. In this way, when manufacturing granular hardened products using fluidized bed combustion ash as the main raw material, the amount of added water, stirring method, curing conditions, and steam treatment conditions must be appropriately selected according to the properties of the fluidized bed combustion ash. It is necessary.

The size of the flow gvJ layer combustion ash in the granular hard body according to the present invention:
In order to increase IT consumption, it is desirable to utilize it as a civil engineering material. It is necessary to have an irregular shape and a wide particle size distribution. Therefore, as a stirring method when molding the raw material mixed powder τ together with moisture into granules, it is preferable to use a stirring method in which the stirring blade and the material to be stirred come into contact with each other efficiently. In other words, a fixed stirring tank in which ribbons, screws, etc. are rotated with two shafts in opposite directions at a speed of 10 Orpm or more, or a stirring tank in which the stirring tank is relatively rotated in a paper storage, The 11th row is preferably one in which the blades rotate in the opposite direction to the P stirring tank at a speed of 100 rpm or more.It is also preferable to perform a crushing treatment if necessary after the atmospheric pressure steam treatment step. This is because particles molded by the crushing process adhere to each other, and by performing the atmospheric pressure steam treatment in one stream, the applied T and strength increase, which has a negative effect on the particle size distribution. rll (= ( For example, suitable methods include a method using a pre-drop method, a method using two rotors rotating in opposite directions, and a method using a rough machine such as a show crusher.

The main features of the granular hardened material according to the present invention when used as civil engineering materials such as road materials, backfill materials, and ground improvement materials are as follows. First, it has a unit volume weight that is considerably smaller than conventional similar materials such as crushed stone and gravel, and yet exhibits ground bearing capacity that is almost equivalent to crushed stone and gravel. That is, it is capable of exhibiting the same ground bearing capacity as crushed stone or gravel with 1/2 to 2/3 the weight. Secondly, road sections and backfill sections are usually in a wet or humid condition, and under such environments, the granular hardened material according to the present invention has the characteristic that the ground bearing capacity increases over time. That's true.

Example Next, Examples and Comparative Examples will be described.

Table 1 shows the chemical composition and physical properties of the fluidized bed combustion ash in Examples and Comparative Examples, and Table 2 shows the proportions of the constituent compounds.

(Left space below) 77;Metb,i The test method for combustion ash, grains, and embossed material is shown below.1. The Blaine specific surface area measurement was performed using the 15) 1-de pressure transfer city + 4 settings: 3SS-100 made by Takaguruma Seisakusho.
Using the shape, air method: teyotta. The liquid limit is TI
S A 1205 (measured based on soil (Ci limit y1. test coal method), plastic limit;
6 (soil plasticity test, horizontal method), 11 rivers were determined. For the strength test, a 10-shoulder specimen was used, and a Mizuya hardness meter (maximum m i ) was used as the testing device.
'30 q) was used.

In addition, 11'6 positive CBR has a maximum dry density of 95' when it is divided into three layers in the vertical direction and each layer is fired and compacted 92 times according to J Engineering S A 1210 (soil tide compaction test method by beam compaction). C after 4 days of water immersion, which corresponds to 10 If
This CBR is given by the following formula from the ridge resistance of a penetrating rod with a diameter of 5 Crn, according to JIS A 1211 (subgrade soil bearing capacity ratio test method).

Example 1 46 parts by weight of water was added to 11 parts of the fluidized Xi Oki ζ incinerated ash shown in Table 1, the stirring tank was set at 3 Q rpm, and the stirring blade (one) in the stirring tank was set at 400 rpm. The mixture was molded into granules while stirring and kneading for 5 minutes, cured in a humid air atmosphere at 50°C for 15 hours, and further treated with normal pressure steam at 30°C for 10 hours. The particle size distribution of the obtained granular cured product is 100% by weight of 20u or less, lQ1. Tl11 or less 70%
, 5 +, ya+ or less 50% by weight, 1 or less 35% by weight
, the θ weight was 1 generation % less than 0.1, and the properties were as shown in Table 3.

Example 2 43 parts by weight of water was added to 100 parts by weight of fluidized bed combustion ash shown in Table 1, and two stirring blades in a fixed stirring tank were heated to 200 parts by weight.
rI)m and 110 rpm for 2.5 minutes while stirring and kneading, the mixture was cured in a humid air atmosphere at 50°C for 15 hours, and then treated with normal pressure steam at 30°C for 10 hours. The particle size distribution of the cured granular material is 100% by weight of 2 mm or less, 95% by weight of 10 mm or less, and 30-11' of 5 M1 or less.
The properties were as shown in Table 3.

Comparative Example 1 45 parts by weight of water was added to 100 parts by weight of the fluidized bed combustion ash shown in Table 1.
Add part by weight and pay for granulation! 4 pieces were molded into granules at 35 rpm for 10 minutes, heated for 15 hours in a humid atmosphere at 50°C, and then treated with normal pressure steam at 30°C for 10 hours. The particle size 21i of the granular hardened material obtained by 14 is less than 20M14 100 iF (1'tk, %, 10
The weight was 95% by weight, the weight was 30% by weight, and the properties were as shown in Table 3.

Comparative Example 2 45 parts by weight of water was added to 100 parts by weight of fluidized bed combustion ash shown in Table 1, and the mixture was stirred and kneaded for 1.5 minutes at 3 grpm in a stirring tank and 40 Orpm using the stirring blade in the stirring tank. The mixture was molded into granules and cured for 2.0 hours in a humid atmosphere at 50°C. The particle size distribution of the obtained granular cured product is 20 MM or less10
0 weight%, 10 birds or less 70 weight%, 5 birds or less 50 ton iY
%, l +i! ) J or less 35% by weight, 0.1? 0 or less
tonj was 11%, and the characteristics were as shown in Table 3.

The characteristics of river sand with a particle size distribution of 1 bite [A13 5, WJl or less 100 'k'' M Vo, 1 ton or less 70% by weight, 0.1n or less 5% by weight were measured, and the results were as shown in Table 3. there were.

Comparative Example 4 4QmM or less 100% by weight, 20PRIR or less 30% by weight, lQMM or less 55% by weight, 5 or less 35% by weight
The characteristics of crushed stone having a particle size distribution of 15% by weight below , IL'Taka and 5% by weight below 0.1 Tom were measured, and the characteristics were as shown in Table 3.

(Leaving space below) 4S 3 Effects of Omotesya As explained above, according to the present invention, the main raw material is Fluid 1 Tanjangran incineration ash, which is the exhaust from fluidized bed combustion using coal as fuel, Stir with water that is more than the plasticity limit and less than the absorption limit and formed into granules with a predetermined particle size distribution number, then cured in humid air at room temperature ~ 60°C, and then treated with normal pressure steam. By curing such as Combustion ash is effective as a material in the civil engineering field, and is extremely useful as a technology that contributes to F11 use.

Sender: Kawasaki Heavy Industries, Ltd. ゛\2) し′

Claims (1)

[Scope of Claims] 1 Coal ash generated during fluidized bed combustion in a fluidized bed consisting of coal as a fuel and limestone as a desulfurization agent and spent desulfurization agent contain 60 to 85% by weight of coal ash.
, quicklime or/and slaked lime, so that the blending ratio is 10 to 25% by weight of lime and 5 to 25% by weight of gypsum.
and type II anhydrous gypsum, hemihydrate gypsum or/and 2
In the method of adjusting the mixed powder by adding water gypsum as necessary, adding water to this mixed powder, kneading, and curing, the amount is greater than the plastic limit of the mixed powder and less than the liquid limit. Add water to the mixed powder and stir. 0% by weight for particle diameters of 40 mm or more, 70-100% by weight for particle diameters of 20 mm or less, 50-100% by weight for particle diameters of 10 mm or less, and 30% by weight for particle diameters of 5 mm or less.
100% by weight or less, 5 to 50% by weight with a particle size of 1 mm or less, and 10% by weight or less with a particle size of 0.1 mm or less. manufacturing method. 2 Claim 1, which involves crushing the hardened material after curing
A method for producing a hardened product using fluidized bed combustion ash as a main raw material as described in 1.