JP3214088B2 - Manufacturing method of desulfurization material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a desulfurized material by recovering unreacted lime-based desulfurized material discharged from a fluidized-bed boiler.

[0002]

2. Description of the Related Art In order to desulfurize a fluidized-bed boiler, lime-based particles such as limestone and dolomite are blown into the boiler. The lime-based particles blown into the furnace react with sulfur oxides (SO _x ) and are then discharged out of the furnace together with the exhaust gas. Of the blown lime-based particles to the furnace, the ratio of reacting with SO _x is about 30% or less.

[0003]

As described above, in spite of a large amount of unreacted lime-based particles remaining in the dust discharged from the fluidized-bed boiler, the unreacted lime-based particles have not been used. It was a large amount of industrial waste without being reused for desulfurization.

An object of the present invention is to open the way to collect and reuse this unreacted lime-based particles as a desulfurizing material.

[0005]

According to a first aspect of the present invention, there is provided a method for producing a desulfurizing material, wherein a collected matter of an exhaust gas collecting device of a boiler into which lime-based particles are blown into a furnace is classified to collect coarse particles. In the manufacturing method of desulfurizing material as desulfurizing material, obtained by classification
After sculpting the coarse particles, they are classified again.
A method for producing a desulfurized material, which collects coarse particles obtained by re-classification, digests and granulates the resulting material to obtain a desulfurized material composed of large-diameter particles. It is characterized by adding and granulating.

[0006] According to a second aspect of the present invention, there is provided a desulfurizing material, wherein lime-based particles are blown into a furnace, and a collected matter of an exhaust gas dust collecting apparatus of a boiler is classified, and coarse particles are recovered and used as a desulfurizing material. In the method of the above, the coarse fraction obtained by the classification is
After looping, classify again and use this classification again.
A method for producing a desulfurized material, wherein the obtained coarse particles are collected and digested together with digestion to obtain a desulfurized material composed of large-diameter particles, characterized in that water glass is used as a binder during granulation. Things.

In a third aspect of the present invention, there is provided a method for producing a desulfurized material.
Collection of flue gas dust collector of boiler where child is blown into furnace
Of desulfurized materials by classifying materials and collecting coarse particles to make desulfurized materials
In the granulation method, the obtained desulfurized material is digested and granulated
And a desulfurizing material manufacturing method to be a desulfurizing material composed of large-diameter particles.
There are, and is characterized in this <br/> and granulation by addition of coal dust during granulation.

[0008] The method for producing a desulfurized material according to claim 4 is based on claim 3.
In the method, the coarse particles obtained by the classification are subjected to scalping treatment, then classified again, and the coarse particles obtained by the classification again are collected, digested, and subjected to granulation. is there.

[0009] The method for producing a desulfurized material according to claim 5 is based on claim 1.
5. The method according to any one of items 4 to 4 , characterized in that the granulated material is dried to increase its strength.

[0010] The method for producing a desulfurized material according to claim 6 is characterized by claim 5.
In the method, it is characterized in the use of boiler exhaust <br/> gas after dust collection on drying of the granulation product.

Hereinafter, the present invention will be described in more detail .

[0012] stream in Fluidized Bed Boiler, in the layer, the fuel which has been adjusted to a predetermined particle size, lime desulfurizing material such as limestone, dolomite, fluid medium, such as silica sand is supplied, if necessary. The lime-based desulfurizing material is first heated and decarbonated. Further, on the surface of the desulfurizing material, a film of sulfate reacting with the sulfur oxide in the combustion exhaust gas is generated. When this desulfurized material stays in the furnace, it collides with other particles in the fluidized bed and the particle size becomes small. When this desulfurized material is reduced to a predetermined size, it is conveyed by airflow and discharged out of the boiler system. The dust discharged outside the boiler system and collected by the dust collector contains the desulfurizing material, the combustion ash, and the unburned carbon. The latter burnt ash and unburned carbon have significantly smaller particle sizes than the former desulfurizer. Therefore, if the particles are classified into a coarse particle and a fine particle by classifying at a predetermined particle size, the desulfurized material and ash and unburned carbon can be separated.

The classifier is preferably an air classifier. This is because part of the ash and unburned portion of the coal is porous, and it is desirable not only to separate the particle size as with a mesh sieve, but also to classify by adding specific gravity as with an air classifier .

On the surface of the coarse particles (lime-based particles) thus recovered, a sulfate substance is formed in a film form. In the method for producing a desulfurizing material according to claims 1, 2 and 4, the sulfate substance on the surface of the particles is subjected to scalping (peeling). When the film of the sulfate substance is removed in this way, the desulfurizing material naturally has good desulfurization reactivity.

In order to perform scalping, light grinding may be performed, for example, with a ball mill or the like. After the scalping treatment, the powder is classified and separated into fine particles rich in sulfate substance and lime-based particles. The fine powder rich in the sulfate substance may be used for other purposes.

The desulfurized material regenerated by such a method has a smaller particle size than the desulfurized material initially used. Therefore,
The disadvantage is that the residence time in the fluidized bed is short. However, since there is no need for decarboxylation, the heat consumption is reduced, and desulfurization in the temperature rising process immediately after being blown into the furnace can be expected .

[0017] than the surface of the desulfurizing material particles prepared by the above method is covered in plaster, in the present invention to break the plaster layer of the surface by digestion. Further, desulfurizing material obtained by the above how, since smaller particle size than that of the original, to produce a large desulfurizing material of particle size and granulated.

That is, water is added to the obtained lime-based particles for granulation. After sufficient digestion to form slaked lime (including slaked lime as a main component), granulation with water as a binder yields a granulated product with high strength. If the quicklime (CaO) content of the lime-based particles is high and the strength of the granulated material is expected to be sufficiently high, digestion and granulation may be performed simultaneously.

To perform granulation, a rolling granulator, briquetter, or the like may be used. Alternatively, a large compact or hardened body may be prepared, and crushed and classified to obtain particles having a predetermined particle size.

[0020] If the granulating try to lime particles (those recovered above SL how) to gypsum and aluminum oxide is mixed, with slaked lime and hydration reaction, curing of ettringite is formed. Since the hydration reaction is faster as the specific surface area of the reactant is larger, it is effective to grind the granules before granulation.

The CaO contained in the obtained particles is Ca
When H ₂ O necessary to become (OH) ₂ is sprayed about 1.2 times the theoretical value and digested with a kneader, a dry fine powder is obtained.

In the present invention, such granulation is performed.
In addition, the following additives for improving the strength are added.

[0023]  Claim1Of desulfurizing materialsLaw Construction To increase the strength of the grainToLime to be granulated
Add cement or slag powder to the particlesYou.Cement and slur
The strength increases as the amount of powder added increases, but the cost also increases.
As it gets higher, the usual amount is 20% or less
It is preferred that

[0024]  Claim2Of desulfurizing materialsLaw Construction Use water glass as a binder when granulating.
To. This, The specific surface area of the hydrate increases, the desulfurization efficiency
Is improved. It also increases the strength of the hot granulation.
Therefore, the desulfurization material is hardly powdered in the furnace. Therefore,
The residence time of the desulfurized material in the furnace can be lengthened.

[0025] Although strength with increasing amount of water glass is high, because the cost is also increased as it, the amount of water glass is preferably 5% or less.

[0026]  Claim3Of desulfurizing materialsLaw Construction When coal powder is added to lime-based particles to be granulated,
It becomes a desulfurizing material containing coal powder. This coal powder is desulfurized
It is carbonized and burned when it is put into the furnace. this
The coal powder inside the desulfurization material has slaked lime around it.
Therefore, the carbonization speed is high and the combustion speed is high.

Since the burning mark of the coal powder becomes void, the desulfurizing material becomes porous. As a result, the desulfurization efficiency of the desulfurization material also increases.

The coal powder preferably has a particle size of 100 μm or less, and its addition amount is preferably 50 wt% or less.

Note that two or more of the above methods are adopted.
The granulation may be performed by using.

[0030] In the above how, when drying the granulated product, the strength of granules is increased by the curing of the slaked lime. The drying temperature is preferably about 40 to 120 ° C.

When the exhaust gas of the boiler is used as a heat source gas for drying, the carbon dioxide gas in the exhaust gas reacts with the hydroxide such as slaked lime in the granulated product. Then, a carbonate film is formed on the surface of the granulated material. Thereby, the strength and surface hardness of the granulated material are increased.

At this time, excess steam is added, and 40-80
When left at about ° C, ettringite minerals are formed, and more robust particles are obtained.

The dried boiler exhaust gas is used for drying the granulated material.
When you use, Ca _{(OH) 2} of the granules the surface of the exhaust gas C
Reacts with O ₂ to form a strong coating of CaCO ₃ .

[0034]

【Example】ComparisonAn example1  Using coal as fuel and limestone with a particle size of 1 to 3 mm as desulfurizer
From the fluidized-bed boiler ash used in
A sulfur material was obtained. This fluidized-bed boiler uses a cyclone for the dust collector.
A bag filter is installed, but the filter contains a lot of coarse particles.
Collect waste generated from Ecron and produce desulfurized materials
did.

The cyclone waste was classified by an air classifier so that the screen sieve particle diameter became 44 μm. The average weight ratio of calcium oxide of the waste before classification was 24%, but the concentration of calcium oxide on the 44 μm net after classification was 45%. Further, the specific surface area before classification was 2600 cm ² / g, but the specific surface area on the 44 μm net after classification was 210
It was 0 cm ² / g.

It was confirmed that the 44 μm mesh could be sufficiently used as a desulfurizing material.

[0037]ComparisonAn example2 Comparison Table on the 44 μm mesh obtained in Example 1 using a ball mill
5000cm area²/ G. This powder 100
Add 17 kg of water to each kg and knead with a stirrer to digest
I let you. The temperature in the stirrer at this time is 80 due to the heat of hydration of quicklime.
° C. The water content after kneading was 2%.

The kneaded product was rolled with a rolling granulator to supply 45 kg of water.
Granulated while adding. The granulated material is classified with a screen sieve,
mm grains were obtained.

It was recognized that these 1 to 3 mm particles can be sufficiently used as a desulfurizing material.

Example 1 (Example of Claim 1 ) In Comparative Example 2, the same procedure was followed except that 12 kg of Portland cement powder was added during granulation.
mm grains were obtained. It was confirmed that these grains could be sufficiently used as a desulfurizing material. The crushing strength of the grains was measured and found to be higher than that of Comparative Example 2.

It should be noted that granules having a size of 1 to 3 mm were obtained in the same manner except that 12 kg of crushed blast furnace slag (having a particle size of 20 μm or less) was added instead of the cement. It was confirmed that these grains could be sufficiently used as a desulfurizing material. The crushing strength of the grains was measured and found to be higher than that of Comparative Example 2.

[0042] Example 2 (Example of Claim 2) Comparative Example 2, in Example 1, was repeated except that water glass (Baume 42, silicofluoride saw ratio 2.5) was added 2kg when and digested To obtain particles of 1 to 3 mm. It was confirmed that these grains could be sufficiently used as a desulfurizing material. The crushing strength of the grains was measured and found to be higher than that of Comparative Example 2.

[0043] Example 3 (Example of Claim 3) Comparative Example 2, in Examples 1 and 2, the upper 44μm network component when pulverized with a ball mill, together except for adding coal 30kg and in the same manner Grains of 1-3 mm were obtained. It was confirmed that these grains could be sufficiently used as a desulfurizing material.
It was recognized that desulfurization could be performed slightly better than Comparative Example 2 and Examples 1 and 2 using this desulfurizing material.

[0044]

As is clear from the above embodiments, according to the present invention, unreacted desulfurized material can be recovered from the used desulfurized material discharged from the boiler and reused. Therefore, according to the present invention, it is possible to reduce the amount of waste of boiler discharge dust.

In particular, according to the present invention , a desulfurized material having a large particle size and a large particle strength can be manufactured. According to the method of claim 4 , a reduction in the amount of carbon dioxide emitted to the atmosphere can be expected. According to the method of claim 5 , the surface hardness of the particles can be increased.

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B09B 3/00 301 B01D 53/34 124Z C01F 11/02 F23J 15/00 B F23J 15/00 (56) -271613 (JP, A) JP-A-3-89916 (JP, A) JP-A-3-242226 (JP, A) JP-A-61-18422 (JP, A) JP-A-48-18164 (JP, A) JP-A-2-194836 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 20/00-20/34 B01D 53/34

Claims (6)

(57) [Claims] 1. A lime-based particles and classified the collection of the exhaust gas dust collector of the boiler to be blown into the furnace, in the method for producing a desulfurizing material to the coarse fraction is recovered desulfurizing material, obtained by classification The above coarse particles were sculpted
Then, it is classified again, and the coarse particles obtained by this classification again
A method for producing a desulfurized material, wherein the desulfurized material is recovered and digested and granulated to obtain a desulfurized material comprising large-diameter particles, wherein granulation is performed by adding cement and / or slag powder during granulation. Method for producing desulfurized material. 2. A lime particles are classified matter trapped in the exhaust gas dust collector of the boiler to be blown into the furnace, in the method for producing a desulfurizing material to the coarse fraction is recovered desulfurizing material, obtained by classification The above coarse particles were sculpted
Then, it is classified again, and the coarse particles obtained by this classification again
A method for producing a desulfurizing material, wherein the desulfurizing material is recovered, digested and granulated to obtain a desulfurizing material comprising large-diameter particles, wherein water glass is used as a binder at the time of granulation. 3. A desulfurization method according to claim 1, wherein the lime-based particles are blown into a furnace, and the collected matter of an exhaust gas dust collector of a boiler is classified, and the coarse particles are collected to produce a desulfurization material. A method for producing a desulfurized material which digests and granulates the material to obtain a desulfurized material comprising large-diameter particles, wherein the method comprises the step of granulating by adding coal powder during granulation. . 4. The method according to claim 3, wherein the coarse fraction obtained by the classification is subjected to scalping treatment, then classified again, and the coarse fraction obtained by the second classification is recovered, digested and granulated. A method for producing a desulfurizing material. 5. The method for producing a desulfurized material according to claim 1, wherein the granulated material is dried to increase its strength. 6. The method for producing a desulfurized material according to claim 5, wherein boiler exhaust gas after dust collection is used for drying the granulated material.