JP4170007B2 - Method for producing cement clinker or cement raw material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing cement clinker or cement raw material, more particularly, as a raw material, relates to a method for manufacturing cement clinker or cement raw material in the case of utilizing waste bring chlorine-alkali components in the kiln.
[0002]
[Prior art]
In the conventional cement manufacturing method and its apparatus, when a raw material contains a chlorine / alkali component, the chlorine / alkali component is circulated and concentrated between the kiln and the suspension preheater, and the chlorine concentration in the bottom cyclone raw material is 5000 ppm. If exceeded, there was a problem that cyclone clogging occurred.
Therefore, while restricting the introduction of low melting point substances such as chlorine and alkali that induce cyclone clogging as much as possible, part of the exhaust gas is extracted from the kiln inlet hood to remove chlorine components from the kiln, and in the raw material of the bottom cyclone A so-called chlorine bypass method is adopted in which the chlorine concentration is 5000 ppm or less.
[0003]
However, in recent years, the cement industry is expected to treat various types of waste, and technological development that uses waste containing chlorine and alkali components (for example, shredder dust, general waste, vinyl chloride, glass, ceramics, etc.) Needs to advance came out.
When such waste is used, the amount of chlorine and alkali introduced increases, so even if the chlorine and alkali components are extracted by the chlorine bypass of the conventional method, There is a problem that the chlorine concentration of the water exceeds 5000 ppm, and the cyclone clogging occurs.
[0004]
On the other hand, in an eco-cement manufacturing apparatus that uses incinerated ash containing a large amount of chlorine as a raw material, a cyclone preheater is not provided in order to avoid the above problem. However, the method of the eco-cement process that does not use the cyclone preheater has a problem that the heat loss increases, so that it is not particularly advantageous in a large plant.
[0005]
[Problems to be solved by the invention]
As described above, treatment with cement manufacturing equipment such as combustible waste containing chlorine, waste glass, shredder dust, etc. is expected, and in treating these waste, cyclone clogging due to chlorine and alkali components is expected. There is an urgent need to take measures. In view of the above problems, the present invention is a cement clinker or cement that does not cause cyclone clogging even if the chlorine concentration in the raw material exceeds 5000 ppm after preheating / calcining the raw material using a cyclone preheater. It aims at providing the manufacturing method of a raw material.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the cement clinker or the method for producing a cement raw material according to the present invention includes at least one selected from the group consisting of a low temperature raw material, a cement clinker, air and water in the bottom cyclone of the suspension preheater. The above-mentioned additive is introduced and the raw material temperature in the bottom cyclone is set to 300 to 770 ° C., whereby the chlorine / alkali component is solidified .
[0007]
The chlorine / alkali component volatilizes in the process of being heated to 1550 ° C., but is taken into the raw material again below the melting point, and is circulated between the suspension preheater and the kiln and concentrated. When the chlorine concentration of the bottom cyclone exceeds 5000 ppm by this circulation concentration, the viscosity of the raw material increases, and the coating grows on the bottom cyclone wall surface. If this coaching falls off, so-called cyclone blockage such as clogging occurs. However, in the cyclone above the bottom cyclone, the raw material temperature is below the melting point of the chlorine and alkali components NaCl and KCl , that is, 770 ° C. or less , and no clogging occurs. 830 to 850 ° C., which is above the melting point of this chlorine / alkali component.
Since the bottom cyclone raw material temperature is set to 300 to 770 ° C. , the viscosity of the raw material can be suppressed. Therefore, even if the circulating concentration of chlorine and alkali components exceeds 5000 ppm, the adhesion of the coating does not occur, and the cyclone clogging is prevented. As a result, the present invention has been completed.
[0008]
In the present invention, the chlorine / alkali component means potassium chloride (KCl), sodium chloride (NaCl), lead dichloride (PbCl ₂ ), zinc chloride (ZnCl ₂ ), potassium sulfate (K ₂ SO ₄ ), sodium sulfate ( It includes those containing Na ₂ SO ₄ ).
The cement clinker is a semi-finished product manufactured in the cement baking process and is cooled by a cooler. A cement raw material means what is manufactured as what can replace a part of natural raw materials, such as a limestone, clay, and an iron raw material, by processing a waste etc. suitably.
[0009]
Material temperature in the bottom cyclone is particularly preferable to the 700 to 750 ° C..
Moreover, it is more preferable to add a low temperature raw material among the low temperature raw material, cement clinker, air and water into the bottom cyclone.
Furthermore, it is preferable that the additive is introduced between the outlet of the calcining furnace on the upstream side of the bottom cyclone and the inlet of the bottom cyclone. Thereby, it is possible to prevent the decarboxylation rate of the raw material that has passed through the calcining furnace from being lowered.
[0011]
Here, the bottom cyclone refers to the lowermost cyclone among the plurality of cyclones constituting the suspension preheater. Further, the upper cyclone is a cyclone that is higher than the bottom cyclone.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a cement clinker or cement raw material manufacturing apparatus according to the present invention. As shown in FIG. 1, the suspension preheater includes four stages of cyclones, a first stage cyclone 1 to a fourth stage cyclone 4. The fourth-stage cyclone is hereinafter referred to as a bottom cyclone. The suspension preheater has a calcining furnace 5 provided between the third-stage cyclone 3 and the bottom cyclone 4. The calcining furnace 5 includes a calcining burner 6 and can decarboxylate limestone in the raw material. A cyclone chute 7 is provided at the raw material outlet of the bottom cyclone 4, and the cyclone chute 7 is connected to a rotary kiln 8 via a kiln inlet hood 9. The rotary kiln 8 includes a kiln burner 10 and can be fired by heating the raw material to 1550 ° C. A cooler 11 is provided at the outlet of the rotary kiln 8 so that the cement clinker obtained in the rotary kiln 8 can be cooled.
[0013]
On the other hand, a waste heat power generation facility 12 is provided in the upper part of the first-stage cyclone 1, and can generate power by reusing the waste heat of the suspension preheater. A chimney 14 is provided at a subsequent stage of the waste heat power generation facility 12 via a dust collector 13 and can be exhausted after removing dust and the like in the gas.
A duct to the dust collector 15 is provided at the exit flue of the bottom cyclone 4 and the exit of the kiln inlet hood 9. The dust collector 15 can separate dust containing chlorine / alkali components from the gas. The gas-side outlet of the dust collector 15 is connected to the outlet flue of the second-stage cyclone 2, and the dust-side outlet is provided with a salt recovery facility 17 via a heavy metal scouring facility 16. The heavy metal smelting facility 16 can separate and remove heavy metals in the dust, and the salt recovery facility 17 can recover the alkali metal salt.
In addition, the continuous line in a figure shows the flow of things, such as a raw material, and a dotted line shows the flow of gas.
[0014]
According to such a configuration, first, when a raw material containing a chlorine / alkali component is introduced into the outlet flue of the second-stage cyclone 2, the raw materials are the first-stage cyclone 1, the second-stage cyclone 2, and the third-stage cyclone. Stage cyclones 3 are introduced in this order and gradually preheated. Next, the raw material enters the calcining furnace 5, and the limestone in the raw material is decarboxylated to become CaO and then introduced into the bottom cyclone 4. Further, the raw material passes through the cyclone chute 7 from the bottom cyclone 4 and enters the rotary kiln 8. The raw material is gradually heated in the rotary kiln 8, and while the mineral mineral is heated to 1550 ° C., the production of cement mineral proceeds and becomes a cement clinker. The clinker is cooled to 1450 ° C. in the kiln 8, then discharged to the clinker cooler 11, and further cooled by the cooler 11.
[0015]
On the other hand, chlorine / alkali components (KCl, NaCl, PbCl ₂ , ZnCl ₂ , K ₂ SO ₄ , Na ₂ SO _4, etc.) brought into the kiln 8 are volatilized while being heated to 1550 ° C. The volatilized chlorine / alkali component is sent as a gas to the suspension preheater, but is taken into the raw material again at a temperature equal to or lower than the melting point, and enters the kiln 8 again. In this way, the chlorine / alkali component circulates between the suspension preheater and the kiln 8 and is concentrated. If the chlorine concentration in the bottom cyclone 4 exceeds 5000 ppm by this circulation concentration, the viscosity of the raw material increases, and the coating grows on the wall surface of the bottom cyclone 4. And so-called cyclone occlusion occurs such that this coaching falls off and the cyclone chute 7 is clogged.
[0016]
Therefore, in the present embodiment, the raw material temperature of the conventional bottom cyclone 4 is reduced from 830 to 850 ° C. to 300 to 770 ° C. so as to be lower than the melting points of NaCl and KCl . As a result, NaCl and KCl, which are chlorine and alkali components , are solidified, and the viscosity of the raw material can be suppressed. Even if the circulating concentration of the chlorine / alkali component exceeds 5000 ppm, the adhesion of the coating does not occur, and the cyclone clogging can be prevented. Material temperature of the bottom cyclone 4, more preferably be reduced to 700 to 750 ° C.. When the temperature is lowered to less than 700 ° C., the loss of heat increases. Further, at temperatures exceeding 750 ° C., it is difficult to keep the melting point of NaCl and KCl below. Although the amount of heat is lost when the raw material temperature is lowered, there is a great merit that the waste treatment is expanded more than the loss.
[0017]
Dust containing solidified chlorine / alkali components is collected by the dust collector 15 through a duct provided in the exit flue of the bottom cyclone 4 and through a duct provided in the kiln inlet hood 9. The dust collector 15 separates and removes dust and the like containing solidified chlorine / alkali components from the gas. The gas from which dust and the like have been removed is returned to the first-stage cyclone 1 again. In addition, the solidified dust and the like containing chlorine and alkali components are sent to the heavy metal refining facility 16 where the heavy metals and the like are separated and removed, and then sent to the salt recovery facility 17 to recover the chlorine and alkali components. it can.
[0018]
As means for bringing the raw material temperature of the bottom cyclone 4 to 300 to 770 ° C. , the apparatus shown in FIG. 2 can be used. As shown in FIG. 2, a raw material bypass chute 18 is installed between the raw material outlet of the first stage cyclone 1 and the raw material inlet of the bottom cyclone 4. The raw material bypass chute 18 includes a rotary valve 19 for air sealing. In order not to inhibit the decarboxylation reaction of the calcining furnace 5 as much as possible, it is preferable to arrange the outlet of the raw material bypass chute 18 on the bottom cyclone 4 side in a pipe line between the calcining furnace 5 outlet and the bottom cyclone 4 inlet.
[0019]
According to such a configuration, the raw material is preheated while passing through the first stage cyclone 1 to the third stage cyclone 3 and enters the calcining furnace 5. In the calciner 5, the limestone in the raw material is decarboxylated to become CaO. The raw material at 830 to 850 ° C. after the decarboxylation reaction and the low temperature raw material at 350 to 400 ° C. sent from the first stage cyclone 1 through the raw material bypass chute 18 are mixed, and the raw material temperature in the bottom cyclone 4 Decreases rapidly to 700-750 ° C. And since a chlorine and an alkali component solidify, it can prevent that coaching produces | generates on the wall surface of the bottom cyclone 4, and can avoid clogging of a cyclone.
[0020]
Here, FIG. 2 shows an example of means for lowering the raw material temperature of the bottom cyclone 4, and the present invention is not limited to FIG. The raw material bypass chute 18 is provided at the raw material outlet of the first stage cyclone 1, but can also be provided in the second stage cyclone 2 or the third stage cyclone 3. Moreover, it replaces with the said means to add a low temperature raw material, Cement clinker which is a semi-finished product, air, water, etc. can also be added.
[0021]
【The invention's effect】
As described above, according to the present invention, a cement clinker that does not cause cyclone clogging even if the chlorine concentration in the raw material exceeds 5000 ppm after preheating / calcining the raw material using a cyclone preheater. A method and apparatus for producing a cement raw material can be provided. In addition, by eliminating the cyclone clogging, the present invention and the chlorine bypass system can be used in common, so that it is possible to treat chlor-alkali-containing waste that has been hated in ordinary cement manufacturing plants. Combined with the number of locations in the country, waste disposal and recycling in Japan can be promoted.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a method for producing a cement clinker or a cement raw material according to the present invention.
FIG. 2 is a schematic view showing an example of a cement clinker or cement raw material manufacturing apparatus according to the present invention.
[Explanation of symbols]
1 1st stage cyclone 2 2nd stage cyclone 3 3rd stage cyclone 4 4th stage cyclone (bottom cyclone)
5 Calcining furnace 6 Calcining burner 7 Cyclone chute 8 Rotary kiln 9 Kiln inlet hood 10 Kiln burner 11 Cooler 12 Waste heat power generation equipment 13, 15 Dust collector 14 Chimney 16 Heavy metal refining equipment 17 Salt recovery equipment 18 Raw material bypass chute 19 Rotary valve

Claims (3)

In the method for producing cement clinker or cement raw material, at least one additive selected from the group consisting of low temperature raw material, cement clinker, air and water is introduced into the bottom cyclone of the suspension preheater, A method for producing a cement clinker or a cement raw material, wherein a chlorine / alkali component is solidified by setting the raw material temperature to 300 to 770 ° C.   The method for producing a cement clinker or a cement raw material according to claim 1, wherein the chlorine concentration in the raw material in the bottom cyclone exceeds 5000 ppm.   The method for producing a cement clinker or a cement raw material according to claim 1 or 2, wherein the additive is introduced between an outlet of the calciner on the upstream side of the bottom cyclone and an inlet of the bottom cyclone. .

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