JP3683870B2 - Dust water washing system and dust water washing method - Google Patents

Description

【００４２】
同表より明らかなように、比較例１に比べ、実施例２は、新規水量を３分の２としても、水洗ケーク中の残留塩素量が同程度であることが判る。また、実施例１は、新規水量が実施例２と同程度であっても、水洗ケーク中の残留塩素量が大幅に低減していることが判る。従って、遠心分離器の分離水の一部を溶解槽に戻すことによって、より少ない新規水量でダストの水洗処理を行うことができ、遠心分離器からケークを排出する直前にケークを洗浄することが水洗ケーク中の残留塩素量の低減に大きく寄与していることが判る。
【００４３】
【発明の効果】
以上説明したように、本発明にかかるダスト水洗システム及びダスト水洗方法によれば、少量の水によって効率よく焼却飛灰等のダストから水溶性成分を溶出させることができるとともに、コンパクトな設備でダストの洗浄を行うことができ、処理量の大きな案件についても容易に対応することが可能となる。
【図面の簡単な説明】
【図１】本発明にかかる水洗システムの一実施の形態を示すフローチャートである。
【図２】図１の水洗システムで使用される遠心分離器の一例を示す概略断面図である。
【図３】従来用いられているベルトフィルタと、本発明にかかるダスト水洗システムで利用した遠心分離器とで、ダスト処理量（トン／日）と設置面積（平方メートル）の関係を比較したグラフである。
【符号の説明】
１ ダスト水洗システム
２ 遠心分離器
２ａ ケーシング
２ｂ 内筒
２ｃ 胴部
２ｄ 均等分離装置
２ｅ スクリューコンベア
２ｆ スラリー供給路
２ｇ 洗浄水供給路
２ｈ ケーク排出口
２ｉ 堰板
２ｊ 分離水搬送路
２ｋ 分離水排出口
３ 溶解槽
４ 遠心分離器
５ 溶解槽
６ ダスト貯蔵槽
７ スラリーポンプ
８ スラリーポンプ
９ ポンプ
Ｃ１ ケーク
Ｃ２ ケーク
Ｄ ダスト
Ｓ１ スラリー
Ｓ２ スラリー
Ｗ１ 新規水
Ｗ２ 新規水（洗浄水）
Ｗ３ 新規水（溶解水）
Ｗ４ 分離水
Ｗ５ 循環水
Ｗ６ 洗浄水
Ｗ７ 溶解水
Ｗ８ 分離水
Ｗ９ 循環水
Ｗ１０ 回収水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dust water washing system and a dust water washing method, and more particularly, a dust water washing system for effectively removing waste by removing volatile components such as chlorine and heavy metals from dust such as incineration fly ash and chlorine bypass dust. And a dust washing method.
[0002]
[Prior art]
In recent years, recycling of waste such as incineration fly ash by using cement as a raw material has been promoted. However, as the treatment amount of waste increases, the amount of volatile components such as chlorine brought into the cement kiln also increases, causing problems such as blocking of preheaters in cement manufacturing facilities. Therefore, after removing a chlorine component etc. from incineration fly ash etc. beforehand, it uses as a cement raw material.
[0003]
At this time, using the water-soluble chlorine compound that is easily dissolved in water, incineration fly ash etc. and water are mixed to elute chlorine, and then filtered using a belt filter etc., and the resulting cake is cemented. It is used as a raw material. In addition, the wastewater from the belt filter is purified and the incineration fly ash is effectively used without causing environmental pollution.
[0004]
On the other hand, in chlorine, sulfur, alkali, etc. that cause problems such as clogging of preheaters in cement manufacturing facilities, paying attention to the problem of chlorine, from the kiln bottom of the cement kiln to the bottom cyclone Chlorine bypass equipment for extracting a part of combustion gas from a kiln exhaust gas passage and removing chlorine is used. And also about the chlorine bypass dust which generate | occur | produced in the chlorine bypass facility, like the above-mentioned incineration fly ash etc., it filters using a belt filter etc., The obtained desalted cake is utilized as a cement raw material.
[0005]
[Problems to be solved by the invention]
Incineration fly ash, etc. are washed with water to elute chlorine, and when slurry is filtered and cake is used as a raw material for cement, it is difficult to treat a large amount of water from which chlorine has been eluted. Become. On the other hand, if the amount of water used for water washing of incinerated fly ash or the like is excessively limited, a cake having a desired chlorine concentration or less cannot be obtained and may not be used as a cement raw material.
[0006]
As described above, in recent years, along with the promotion of various types of dusty waste, the importance of removing volatile components such as chlorine and heavy metals contained in dust has increased. If the resulting desalted cake is used as a raw material for cement, etc., as the amount of processing increases, the size of the water washing and filtration equipment increases, requiring a large installation space, and the installation location is limited. In such a case, there was a risk of hindering the introduction of the equipment.
[0007]
Therefore, the present invention has been made in view of the above-mentioned problems in the prior art, and is obtained by efficiently eluting water-soluble components such as water-soluble chlorine from dust such as incineration fly ash with a minimum amount of water. Can be used effectively, and dust can be cleaned with compact equipment even in projects with large throughput, which can cope with an increase in the throughput of various types of dusty waste. An object is to provide a dust water washing system and a dust water washing method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a dust washing system, comprising: a dissolution tank that suspends dust in water and dissolves water-soluble components in the dust in water; and a centrifugal separator of the vertical performing solid-liquid separation of the slurry consisting of discharged dust and water, that a part of the centrifugal separator of the separated water of the vertical and a circulating means for returning to the dissolving tank Features.
[0009]
And according to invention of Claim 1, in order to provide the circulation means which returns a part of separation water of a bowl- shaped centrifuge to a dissolution tank, in a dissolution tank, maintaining supply of new water as much as possible The water-soluble component in dust can be dissolved in water with a larger amount of water, and the water-soluble component in dust can be efficiently washed and removed. In addition, in the present invention, since a vertical centrifuge is used for solid-liquid separation, even if the amount of dust processing increases, the increase rate of the installation area is small, and it is possible to easily cope with a large amount of processing. Can do.
[0010]
The invention according to claim 2 is a dust washing system, wherein the dust is suspended in water and a water-soluble component in the dust is dissolved in water, and the first dissolution tank is discharged. A first vertical centrifuge for solid-liquid separation of the slurry composed of dust and water, and the cake discharged from the first vertical centrifuge and water are mixed to A second dissolution tank for dissolving the water-soluble component in water, a second vertical centrifuge for solid-liquid separation of the slurry discharged from the second dissolution tank, and the first vertical mold Circulating means for returning at least one of a part of the separated water of the centrifuge or a part of the separated water of the second vertical centrifuge to the first dissolving tank or the second dissolving tank; It is provided with.
[0011]
According to the second aspect of the present invention, dust washing and solid-liquid separation are performed in two stages using two vertical centrifuges and dissolution tanks, and at least one of the vertical types is performed. In order to provide a circulation means for returning a part of the separated water of the centrifuge to the dissolution tank, the water-soluble component in the dust is dissolved in the water by a larger amount of water in the dissolution tank while further suppressing the supply amount of new water. The water-soluble component in the dust can be efficiently washed and removed. Moreover, since a saddle-type centrifuge is used for solid-liquid separation, it is possible to easily deal with a large amount of processing.
[0012]
The invention described in claim 3 is the dust washing system according to claim 1 or 2, at least one centrifugal separator of the vertical type, immediately prior to discharging the cake from the vertical centrifuge of, A cleaning means for cleaning the cake with water is provided.
[0013]
According to the third aspect of the present invention, in the vertical centrifuge, since the water is washed immediately before discharging the cake, the water-soluble components in the cake can be efficiently washed and removed.
[0014]
According to a fourth aspect of the present invention, there is provided a dust water washing method in which solid-liquid separation is performed after suspending dust in water and dissolving water-soluble components in the dust in water, and two vertical centrifuges used, the second supplying vertical centrifuge separation water to dissolve the dust supplied to the first vertical centrifugal separator, discharged from the first vertical centrifuge cake with new water solubility, a portion of the centrifugal separator of the separated water at least one of the vertical centrifugal separator of the first or second vertical, fed to a centrifugal separator of the vertical The water-soluble component of the slurry is returned to the dissolution tank in which it is dissolved in water.
[0015]
According to the invention described in claim 4, the dust is washed with water and solid-liquid separated in two stages, and a part of the separated water of at least one of the vertical centrifuges is returned to the dissolution tank. While suppressing the supply amount of new water as much as possible, the water-soluble component in the dust can be dissolved in water with a larger amount of water in the dissolution tank, and the water-soluble component in the dust can be efficiently washed and removed.
[0016]
According to a fifth aspect of the present invention, in the dust water washing method according to the fourth aspect, the separation of the second vertical centrifuge immediately before discharging the cake from the first vertical centrifuge. The cake is washed with water, and the cake is washed with fresh water immediately before the cake is discharged from the second vertical centrifuge. Thereby, the water-soluble component in the cake can be washed and removed more efficiently.
[0017]
According to a sixth aspect of the present invention, as a preferred embodiment of the dust water washing method according to the fourth or fifth aspect, as the dissolved water for the dust, warm water of 30 ° C. or higher and 60 ° C. or lower is used, and It is characterized in that it is used more than twice and less than 20 times. In order to reduce the capacity of the dissolved water or shorten the residence time of the slurry in the dissolution tank, it is preferable to use hot water of 30 ° C. or higher and 60 ° C. or lower.
[0018]
The invention according to claim 7 is the dust water washing method according to claim 4, 5 or 6, wherein the dust is calcium-containing dust, and when the dust is washed with water, It is characterized in that 0.1% or more and 10% or less of dihydrate gypsum is added to the dissolution tank for supplying the dust.
[0019]
According to the invention of claim 7, when washing dust containing calcium such as chlorine bypass dust with water, by suspending the dihydrate gypsum together with the dust, the dihydrate gypsum is used as a seed crystal around it. Calcium can be adhered and grown, and scale adhesion and the like in a subsequent processing system can be prevented. In order to promote the adhesion and growth of the calcium content on the seed crystal, the amount of dihydrate gypsum is preferably set to 0.1% or more and 10% or less of the weight of the dissolved water.
[0020]
The invention according to claim 8 is the dust washing method according to any one of claims 4 to 7, wherein the dust includes at least one of incineration main ash, incineration fly ash, and chlorine bypass dust. Features. Here, incineration fly ash refers to municipal waste stalker fly ash, municipal waste fluidized bed furnace fly ash, sewage sludge incineration fly ash, paper sludge incineration fly ash, organic sludge incineration fly ash, and the like. As a result, waste such as incinerated fly ash can be effectively used as a cement raw material.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an embodiment of a dust rinsing system according to the present invention. This dust rinsing system 1 is roughly divided into two dissolution tanks 3 and 5, two centrifuges 2 and 4, and And a dust storage tank 6.
[0022]
The dissolution tanks 3 and 5 are equipped with a stirrer in a tank formed in a cylindrical shape, and are supplied with dust or a water-washing cake and water to dissolve water-soluble components in the dust and the like in water. Then, a slurry composed of dust and water is discharged.
[0023]
As shown in FIG. 2, the centrifuges 2 and 4 are so-called bowl-shaped centrifuges, and include an inner cylinder 2b fixed to the casing 2a and a rotating body 2c in the casing 2a.
[0024]
A slurry supply path 2f is provided at the upper part of the body part 2c, and an equal separation device 2d for separating the slurry equally in the circumferential direction is disposed at the lowermost part of the slurry supply path 2f. A cleaning water supply path 2g for supplying the cleaning water for the cake from the bottom surface of the trunk portion 2c toward the middle portion of the trunk portion is provided. A screw conveyor 2e that moves the separated water from the slurry upward is provided on the outer periphery of the body 2c, and a dam plate 2i is provided above the screw conveyor 2e. A space from the weir plate 2i to the separated water discharge port 2k is a separated water conveyance path 2j. A cake discharge port 2h is provided at the lowermost portion of the inner cylinder 2b.
[0025]
As shown in FIG. 1, slurry pumps 7 and 8 are disposed between the centrifuge 4 and the dissolution tank 5 and between the centrifuge 2 and the dissolution tank 3, respectively. A pump 9 for transporting the cake to the next process is disposed at the subsequent stage of the centrifuge 2. Moreover, in order to supply water to the centrifuge 2-dissolution tank 5, the water supply apparatus which is not shown in figure is arrange | positioned.
[0026]
Next, operation | movement of the dust washing system 1 which has the said structure is demonstrated. The numerical value N in parentheses in the material flow of FIG. 1 is a solid-liquid ratio, and indicates the weight ratio of water to the weight of dust D supplied from the dust storage tank 6 to the dissolution tank 5. Moreover, in order to accelerate | stimulate melt | dissolution of the water-soluble component in dust, it is preferable to use 30-60 degreeC warm water as a melt | dissolution water of dust.
[0027]
As shown in FIG. 1, the dust D in the dust storage tank 6 is supplied to the dissolution tank 5, and the water-soluble components in the dust D are dissolved water W <b> 7 from the centrifuge 2 and from the centrifuge 4. Dissolves in circulating water W9. The slurry S2 discharged from the dissolution tank 5 is supplied to the centrifuge 4 via the slurry pump 7. In the centrifugal separator 4, the slurry S2 is subjected to solid-liquid separation. At this time, the cake generated by the solid-liquid separation is washed with the cake washing water W6, and the water-soluble components in the cake are further dissolved and removed. Part of the separated water W8 is returned to the dissolution tank 5 as circulating water W9, and the rest is recovered as recovered water W10 and purified.
[0028]
Here, the solid-liquid separation operation of the slurry S2 by the centrifuge 4 will be described with reference to FIG.
[0029]
When the supplied slurry S2 passes through the slurry supply path 2f and reaches the equal separation device 2d of the body portion 2c, it is evenly separated in the circumferential direction by the centrifugal force generated by the rotation of the body portion 2c. Then, solid-liquid separation is performed in the rotating screw conveyor 2e, and the separated water moves upward in the screw conveyor 2e, passes over the weir plate 2i, passes through the separated water conveyance path 2j, and passes through the separated water discharge port 2k. Discharged. On the other hand, the cake moves downward in the screw conveyor 2e, is washed by the washing water W6 supplied from the washing water supply passage 2g in the vicinity of the lower end portion of the inner cylinder 2b, and then is discharged from the cake discharge port 2h. .
[0030]
As shown in FIG. 1, the cake C2 discharged from the centrifuge 4 is supplied to the dissolution tank 3, and the water-soluble component of the cake C2 is dissolved in the new water W3 and the circulating water W5 from the centrifuge 2. To do. The slurry S1 discharged from the dissolution tank 3 is supplied to the centrifuge 2 via the slurry pump 8. In the centrifuge 2, the slurry S1 is solid-liquid separated as described above, and the cake produced by the solid-liquid separation is washed with the new water W2, and the water-soluble components in the cake are further dissolved and removed.
[0031]
A part of the separated water W4 is returned to the dissolution tank 3 as the circulating water W5, a part is used as the cake washing water W6 in the centrifuge 4, and the rest is used in the dissolution tank 5 as the dissolved water W7. The cake C1 discharged from the centrifuge 2 is conveyed to the next process via the pump 9 and can be used as a cement raw material or the like.
[0032]
As described above, in the present invention, W1 (N = 4) is supplied to the dust water washing system 1 as new water, and a part of the water is used as the washing water W2 (N = 1) in the centrifugal separator 2 and the rest. Is used as dissolution water W3 (N = 3) in the dissolution tank 3, and a part of the separation water W4 (N = 7) of the centrifuge 2 is returned to the dissolution tank 3 as circulating water W5 (N = 3). Therefore, it is possible to dissolve water-soluble components with a total of N = 6 water of dissolved water W3 (N = 3) + circulated water W5 (N = 3) and dissolve while maintaining the supply of new water W1 as much as possible. In the tank 3, the water-soluble component in the cake can be dissolved in water with a larger amount of water.
[0033]
Similarly, in the system of the centrifuge 4 and the dissolution tank 5, a part of the separated water W4 of the centrifuge 2 is used as the washing water W6 (N = 1) in the centrifuge 4 and is centrifuged. A part of the separation water W4 (N = 7) of the separator 2 is used as the dissolution water W7 (N = 3) in the dissolution tank 5, and a part of the separation water W8 (N = 7) of the centrifuge 4 is circulated water. Since the water is returned to the dissolution tank 5 as W9, the water-soluble components can be dissolved by the total N = 6 water of the dissolved water W7 (N = 3) + circulated water W9 (N = 3), and the same as above The effect is gained.
[0034]
In addition, about the value of the said solid-liquid ratio N, an example was shown, The solid-liquid ratio N = 6 at the time of melt | dissolution of a water-soluble component is an economical and practical value, It varies in the range of 2 to 20 depending on the properties of the dust. Further, the amounts of the circulating water W5 and W9 and the washing waters W2 and W6 also need to be appropriately changed depending on the situation.
[0035]
In the above-described embodiment, two dissolution tanks and two centrifuges are arranged, but three or more of each are arranged, from a circulating means for returning a part of the separated water of the centrifuge to the dissolution tank, or from the centrifuge Immediately before discharging the cake, it is possible to provide a dust washing system by providing a washing means for washing the cake with water and both of these means.
[0036]
The centrifuge is not limited to a saddle type, and a horizontal centrifuge can be used.
[0037]
A dust containing a large amount of calcium, such as chlorine bypass dust, has a strong adhesion and causes a scale trouble in a processing system such as a dissolution tank. Therefore, by suspending dihydrate gypsum together with dust, using dihydrate gypsum as a seed crystal and adhering and growing the calcium content around it, the adhesion of the calcium content can be reduced, and scale trouble in the latter stage can be reduced. Can be prevented. In addition, in order to promote the adhesion and growth of calcium to the seed crystal, it is preferable that the amount of dihydrate gypsum is 0.1 to 10% or less of the weight of the dissolved water.
[0038]
FIG. 3 shows a conventional belt filter and centrifuges 2 and 4 used in the above-described dust water washing system 1 according to the present invention. The dust processing amount (ton / day) and the installation area (square meter) It is the graph which compared the relationship.
[0039]
As is clear from this graph, the installation area of the belt filter increases in proportion to the amount of dust, whereas in the case of a centrifuge, the installation area of the belt filter increases even if the amount of dust increases. It can be seen that the rate of increase is small. This makes it possible to clean dust with compact equipment even in projects with a large amount of processing.
[0040]
Next, test examples of the present invention will be described. In this test, the case of washing with the dust washing system 1 of FIG. 1 is carried out in Example 1, the washing with the dust washing system 1 of FIG. 1 is carried out, and the case of not washing the cake is carried out in Example 2. A case where neither water circulation nor cake washing was performed was set as Comparative Example 1, and a dust having a chlorine concentration of 14.9% was washed with water. The results are shown in Table 1.
[0041]
[Table 1]

[0042]
As is clear from the table, it can be seen that, compared with Comparative Example 1, Example 2 has the same amount of residual chlorine in the water-washed cake even when the amount of new water is two-thirds. Moreover, even if Example 1 has the same amount of new water as Example 2, it turns out that the amount of residual chlorine in a water-washing cake is reducing significantly. Therefore, by returning a part of the separated water of the centrifuge to the dissolution tank, it is possible to wash the dust with a smaller amount of new water, and to wash the cake immediately before discharging the cake from the centrifuge. It can be seen that it greatly contributes to the reduction of the amount of residual chlorine in the washing cake.
[0043]
【The invention's effect】
As described above, according to the dust water washing system and the dust water washing method according to the present invention, water-soluble components can be efficiently eluted from dust such as incineration fly ash with a small amount of water, and the dust can be removed with compact equipment. Therefore, it is possible to easily deal with a large amount of processing.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an embodiment of a water washing system according to the present invention.
FIG. 2 is a schematic cross-sectional view showing an example of a centrifuge used in the water washing system of FIG.
FIG. 3 is a graph comparing the relationship between the amount of dust treated (tons / day) and the installation area (square meter) between a conventionally used belt filter and a centrifugal separator used in the dust washing system according to the present invention. is there.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dust water washing system 2 Centrifugal separator 2a Casing 2b Inner cylinder 2c Body part 2d Equal separation apparatus 2e Screw conveyor 2f Slurry supply path 2g Washing water supply path 2h Cake discharge port 2i Dam plate 2j Separation water conveyance path 2k Separation water discharge port 3 Dissolution tank 4 Centrifuge 5 Dissolution tank 6 Dust storage tank 7 Slurry pump 8 Slurry pump 9 Pump C1 Cake C2 Cake D Dust S1 Slurry S2 Slurry W1 New water W2 New water (wash water)
W3 New water (dissolved water)
W4 Separated water W5 Circulating water W6 Washing water W7 Dissolved water W8 Separated water W9 Circulating water W10 Recovered water

Claims (8)

A dissolution tank in which dust is suspended in water and water-soluble components in the dust are dissolved in water;
A vertical centrifuge for performing solid-liquid separation of a slurry composed of dust and water discharged from the dissolution tank;
Dust washing system, characterized in that a circulating means for returning a portion of the centrifugal separator of the separated water of the vertical to the dissolving tank. A first dissolution tank in which dust is suspended in water and water-soluble components in the dust are dissolved in water;
A first vertical centrifuge for performing solid-liquid separation of a slurry composed of dust and water discharged from the first dissolution tank;
A second dissolution tank in which the cake discharged from the first vertical centrifuge and water are mixed to dissolve water-soluble components in the cake in water;
A second vertical centrifuge for solid-liquid separation of the slurry discharged from the second dissolution tank;
At least one of the separated water of the first vertical centrifuge or the separated water of the second vertical centrifuge is used as the first dissolution tank or the second A dust rinsing system comprising a circulation means for returning to the dissolution tank. At least one centrifugal separator of the vertical type, immediately prior to discharging the cake from the vertical centrifuge of claim 1 or the cake, characterized in that it comprises a cleaning means for cleaning with water 2. The dust washing system according to 2. In the dust washing method in which solid-liquid separation is performed after the dust is suspended in water and water-soluble components in the dust are dissolved in water.
Using two vertical centrifugal separator, a second vertical centrifuge separation water is supplied to the dissolution of the dust supplied to the first vertical centrifuge of,
Using new water to dissolve the cake discharged from the first vertical centrifuge,
A part of a centrifugal separator of the separated water at least one of the vertical centrifugal separator of the first or second vertical, water-soluble components of the slurry supplied to the centrifuge of the vertical water A dust water washing method characterized by returning to a dissolved dissolution tank. Immediately prior to discharging the cake from the centrifuge of the first vertical, the washing the cake with a vertical second centrifuge separation water, centrifuge the second vertical 5. The dust water washing method according to claim 4, wherein the cake is washed with new water immediately before discharging the cake from the container.   6. The dust washing method according to claim 4, wherein hot water having a temperature of 30 ° C. or more and 60 ° C. or less is used as the dissolved water of the dust in an amount of 2 to 20 times the weight of the dust.   The dust is calcium-containing dust, and when the dust is washed with water, 0.1% or more and 10% or less of dihydrate gypsum of the dissolved water of the dust is dissolved to supply the dust. It adds to a tank, The dust water washing method of Claim 4, 5 or 6 characterized by the above-mentioned.   The dust water washing method according to any one of claims 4 to 7, wherein the dust includes at least one of incineration main ash, incineration fly ash, and chlorine bypass dust.

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