JP6637657B2 - Fly ash processing apparatus and processing method - Google Patents

Description

  The present invention relates to an apparatus and a method for treating fly ash, and more particularly, to an apparatus and a method for treating fly ash containing an alkaline earth metal component such as calcium generated in waste treatment.

Various fuels, wastes, incineration ash such as sludge, incineration fly ash, molten fly ash, etc. may contain harmful heavy metals, and fly ash containing such harmful substances can be landfilled as it is. It is not environmentally preferable, and it is required to perform detoxification processing even when landfilling. In addition, incineration main ash and fly ash contain a large amount of CaO, SiO ₂ , Al ₂ O, Fe ₂ O, etc., and are close to the main components of cement, so that they are increasingly used as cement raw materials. However, these incinerated ash contain a large amount of chlorine, and if used as it is as a cement raw material, the chlorine concentration in the cement will increase. Therefore, it is necessary to remove chlorine. Such detoxification of waste has become a great social demand.

  For example, as a method of removing harmful heavy metals and chlorine, ash dust is washed with a solution having a chloride ion concentration of 2.0 wt% or more for the purpose of enhancing the effect of desalination and heavy metal removal in ash dust cleaning treatment. A method has been proposed that promotes elution of heavy metals contained in ash dust, and introduces carbon dioxide into a washing suspension of ash dust for washing to promote elution of chloride ions from Friedel's salt contained in ash dust. (See, for example, Patent Document 1).

However, the conventional methods including such a method have the following problems.
(I) In the desalination treatment accompanying the washing of ash dust, washing wastewater containing a large amount of salts discharged after the treatment is generated. If such wastewater is discharged as it is, it may affect downstream ecosystems and cause water pollution, and it is necessary to neutralize and remove salts and the like.
(Ii) As a treatment of washing wastewater containing salts after the desalination treatment, a method of evaporating and drying the wastewater to effectively use the obtained solidified salt as a fertilizer or the like may be mentioned. Since a large amount of water must be evaporated in the process of performing the heat treatment, a large amount of energy is required, which is higher than the latent heat of water.
(Iii) Ash dust generated during waste treatment often contains an alkaline earth metal component such as calcium, and is deposited on a desalination treatment line to become an obstructive component of the treatment process, or after treatment. In some cases as impurities.

JP-A-10-128304

  Accordingly, an object of the present invention is to selectively separate alkaline earth metal components such as calcium, which are obstacles in the fly ash treatment step, from incinerated fly ash generated in waste treatment, and to concentrate and recover the fly ash. An object of the present invention is to provide a fly ash treatment apparatus and a treatment method capable of efficiently collecting useful salts and the like contained in ash and the like with lower energy.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by the fly ash processing apparatus and method described below, and have completed the present invention.

The apparatus for treating fly ash according to the present invention,
A washing tank in which powdery or crushed fly ash, washing water and a treating agent are introduced, and a stirring and washing process is performed;
A solid-liquid separation device having a solid recovery section in which a cleaning treatment liquid supplied from the cleaning tank is subjected to solid-liquid separation, and a separated solid component is recovered, and a liquid supply section in which the separated liquid component is supplied. When,
The liquid component is introduced, an evaporation / drying process is performed, and a salt or the like recovery unit for recovering a dissolved component in the liquid component, and a water or the like recovery unit for condensing the evaporated component are provided. And a device,
As the treatment agent, an inorganic acid or an inorganic salt that reacts with an alkaline earth metal component in the fly ash to form a water-insoluble compound,
A heat pump type drying device is used as the evaporating and drying device.

Further, the present invention is a method for treating fly ash,
The powdered or crushed fly ash is mixed and stirred with washing water and an inorganic acid or inorganic salt-based treating agent, and, together with the washing treatment, reacts the treating agent with an alkaline earth metal component in the fly ash. A washing step in which a water-insoluble compound is formed by
A solid-liquid separation step in which the washed cleaning treatment liquid is subjected to solid-liquid separation, the separated solid component is collected, and the separated liquid component is supplied.
An evaporating and drying step in which water in the liquid component is evaporated or separated, a dissolved component in the liquid component is recovered, and the evaporated component is condensed and recovered.
It is characterized by having.

  In the treatment process of incinerated fly ash and the like generated in waste treatment, it is important to efficiently collect salts and the like and to remove and collect calcium and the like which are obstacles in the treatment process as described above. In order to solve such a problem, the present inventor recovers calcium and the like as a water-insoluble substance using a treating agent such as sodium carbonate as described later in the first stage treatment, and further, in the second stage treatment. It has been found that the problem can be solved by evaporating and collecting the salts in the subsequent liquid component by evaporating to dryness using a heat pump type drying apparatus having high energy efficiency. With such a fly ash treatment apparatus and method, it has become possible to efficiently remove impurities and recover useful salts and the like with efficiency and lower energy than ever before.

The present invention is the apparatus for treating fly ash, wherein, as the treating agent, any one of sodium carbonate, potassium carbonate, sodium bicarbonate, sulfuric acid and phosphoric acid or a combination of some of them is used. .
As described above, the alkaline earth metal components such as calcium may cause an obstacle in the fly ash treatment process due to deposition and growth. On the other hand, since the components differ depending on the components of fly ash (the type of waste), it is preferable to select the respective optimal treating agents for the generation and recovery of the water-insoluble compounds of these components. Specifically, in the case of calcium, calcium carbonate, which is a water-insoluble compound, can be generated by using sodium carbonate, potassium carbonate, or the like as a treating agent. By recovering the calcium carbonate by solid-liquid separation, it can be used, for example, as a cement raw material, and valuable materials can be taken out of fly ash, which has been difficult to use in the past.

The present invention is the apparatus for treating fly ash, wherein the heat pump-type drying apparatus is provided with a primary heat exchange section into which the liquid component is introduced, and a high-temperature and reduced pressure provided downstream of the primary heat exchange section. A secondary heat exchange section in which the liquid component is evaporated and dried under the conditions; and a heat-absorbing side of the secondary heat exchange section adiabatically compresses a vapor component created from a part of the liquid component, and again performs a secondary A compressor to be introduced to the heat radiation side of the heat exchange unit;
Compressed steam supplied from the heat radiation side of the secondary heat exchange section exchanges heat with the liquid component in the primary heat exchange section and is condensed and taken out as condensed water, and the heat absorption side of the secondary heat exchange section Wherein the dissolved component in the liquid component is dried and solidified as salts and recovered as a solidified salt.
As described above, in order to collect salts and the like in fly ash, there was a problem that a large amount of energy was required for the evaporation and drying processes. The present invention aims to recover low-energy salts and the like by using a heat pump type drying apparatus having high energy efficiency, and further uses a heat exchange method using a heat medium circulating in a conventional closed flow path. By using a so-called open type heat pump type drying device instead of a closed type heat pump type drying device, a more energy efficient evaporation / drying function was secured. In other words, the secondary heat exchange section has a configuration that does not have a closed loop of the circulating heat medium, compresses the vapor component from the liquid component that has been subjected to the evaporation and drying processing in the secondary heat exchange section, and serves as a high-temperature heat medium. The primary heat exchange unit recirculates heat to the liquid component on the heat absorption side to exchange heat with the liquid component on the heat absorption side, takes out the vapor component that has been cooled further in the primary heat exchange unit as condensed water, and passes the secondary heat exchange unit through the primary heat exchange unit. To achieve a remarkable improvement in energy efficiency by a configuration having a two-stage heat exchange treatment function between two circulation systems of drying and solidifying a liquid component introduced on the heat absorption side and recovering salts as solidified salts. Became possible.

The present invention is the apparatus for treating fly ash, wherein a part or all of the evaporated components collected in the water and the like collecting section has a return flow path introduced into the washing tank as washing water. And
In general, fly ash is mainly composed of inorganic substances, and since there is almost no water and inorganic salts in the liquid component that has been washed and solid-liquid separated, almost no impurities are contained in the evaporated component generated by evaporation to dryness. Not included. Therefore, in the present apparatus, this is treated in the same manner as the clean water and is used as the cleaning water, so that the amount of the cleaning water used can be significantly reduced. Also, even if impurities are contained in the evaporation component, the formation of such a circulation system can greatly reduce the amount of wastewater to the outside, thereby greatly reducing the load of wastewater treatment. became.

The present invention is the method for treating fly ash, wherein, in the evaporating and drying step, a heat pump type drying treatment is performed, and a part or all of the collected evaporating component is used as washing water in the washing step. It is characterized by being used.
As described above, the introduction of a heat pump type drying process into the evaporating and drying process, and the formation of a circulation system consisting of a washing process, a solid-liquid separation process, a storage process, an evaporating to dryness process, and a re-washing process, have brought about an unprecedented emergency. It has become possible to effectively use high energy.

FIG. 1 is an overall configuration diagram illustrating a basic configuration of a fly ash processing apparatus according to the present invention. The block diagram which shows the example of the structure of the heat pump type drying apparatus which concerns on this invention. The whole block diagram which shows the 2nd example of a structure of the fly ash processing apparatus which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The fly ash treatment apparatus according to the present invention (hereinafter referred to as “the present apparatus”) includes a washing tank in which powdery or crushed fly ash, washing water and a treating agent are introduced, and a stirring and washing treatment is performed; Solid-liquid separation of the cleaning treatment liquid supplied from the tank, a solid recovery section in which the separated solid component is recovered, and a liquid supply section in which the separated liquid component is supplied, and a solid-liquid separation device, A liquid component is introduced, an evaporation / drying process is performed, and a recovery unit for salts and the like in which dissolved components in the liquid component are recovered, and a recovery unit for water and the like in which the vaporized components are condensed, And an inorganic acid or an inorganic salt which reacts with an alkaline earth metal component in fly ash to form a water-insoluble compound as a treating agent, and a heat pump type drying device is used as an evaporating and drying device. It is characterized by the following. With such a configuration, it has become possible to remove impurities and recover useful salts and the like efficiently and at a lower energy than ever before.

<Configuration example of this device>
As an embodiment of the present apparatus, a basic schematic overall configuration is shown in FIG. 1 (first configuration example). In the present apparatus, fly ash 1 to be treated is introduced into a washing tank 4 together with a treating agent 2 and washing water 3. In the cleaning tank 4, a water-insoluble compound (for example, calcium carbonate) is generated by a reaction between the treating agent 2 (for example, sodium carbonate) and an alkaline earth metal (for example, calcium) component in the fly ash 1. The generated water-insoluble compound, other components in the fly ash 1 and a part of the treatment agent 2 are supplied from the washing tank 4 as a washing treatment liquid 4 a and introduced into the solid-liquid separation device 5. In the solid-liquid separation device 5, most of the water-insoluble component and the water-insoluble compound are separated as the solid component 5 a and collected through the solid recovery unit 6. The recovered solid component 5a is taken out as a dried cake 6a after being dried, and is used as a cement raw material or the like. The liquid component 5b separated in the solid-liquid separation device 5 is introduced into the storage tank 7 via a liquid supply unit (not shown) as necessary, and is stored temporarily or for a predetermined period. The stored liquid component 5b is introduced into the evaporating and drying device 8, where an evaporating process of water and the like constituting a main component of the liquid component 5b and a drying process of a dissolved component in the liquid component 5b are performed. The evaporating component 8a generated by the evaporating process is condensed, collected through a water and the like collecting unit (not shown), and the dried salt is converted into a solidified salt 8b by a salt and the like collecting unit (not shown). Collected via When the amount and composition (quality) of the fly ash 1 to be treated are stable, the liquid component 5b separated in the solid-liquid separation device 5 is directly evaporated to dryness without providing the storage tank 7. A configuration for introducing the device 8 is also possible.

(Fly ash)
Fly ash 1 to be treated includes various kinds of industrial waste including building waste, incineration ash such as sludge, incineration fly ash, molten fly ash, and various kinds of substances that may contain alkaline earth metal components such as calcium. Waste can be mentioned. This includes not only heat-treated waste such as combustion treatment, but also chemically-treated waste such as chelation treatment and cement solidification treatment. In addition, the fly ash 1 is pretreated in a powdery or crushed state by a pulverizer or the like in advance, and is introduced into the cleaning tank 4 to thereby achieve higher cleaning efficiency and reaction efficiency with the alkaline earth metal component. Can be obtained.

(Washing tank)
In the washing tank 4, it is preferable that the fly ash 1, the washing water 3 and the treating agent 2 are uniformly and quickly stirred. The fly ash 1 and the washing water 3 are stirred and mixed, and the washing process of the fly ash 1 is performed. At this time, the water-soluble component in the fly ash 1 dissolves in the washing water 3 and at the same time, the alkaline earth metal component in the fly ash 1 and the treating agent 2 react. This reaction can ensure high reactivity due to the presence of moisture. The specific reaction will be described later. The water-insoluble compound generated in the cleaning tank 4 is separated from the water-insoluble component in the fly ash 1, the water-soluble component in the fly ash 1, and a part of the treating agent 2 as a cleaning treatment liquid 4a. Supplied from As the washing water 3, city water, clean factory water, well water, or the like is preferably used. Further, the washing tank 4 refers to a device having a predetermined capacity having a function of stirring a mixture of the fly ash 1 and the washing water 3 for a predetermined time, and the stirring function is not limited to the configuration having the stirring means 41 as shown in the drawing. For example, it can be secured by another means such as a rotating drum type cleaning tank 4 (not shown) or a configuration (not shown) such that the cleaning water 3 is introduced as a jet to form a stirring flow. The inside of the washing tank 4 can be efficiently stirred and washed by performing a surface treatment for preventing fly ash or fine particles and fine particles separated therefrom from adhering.

〔Processing agent〕
The treatment agent 2 refers to an inorganic acid or inorganic salt-based reagent which reacts with an alkaline earth metal component such as calcium to generate a water-insoluble compound, and the alkaline earth metal component to be reacted is a fly ash component, That is, since it differs depending on the type of waste and the like, it is preferable to select the optimum treatment agent 2 for each. Specifically, any one of sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), sulfuric acid (H ₂ SO ₄ ), and phosphoric acid (H ₃ PO ₄ ) or It is preferable to use some of these in combination. For example, when calcium oxide (CaO) is contained as an alkaline earth metal component, the use of such a treating agent 2 causes a reaction shown in the following formulas 1 to 5 to cause a calcium carbonate which is a water-insoluble compound. (CaCO ₃ ), calcium sulfate (CaSO ₄ ) and calcium phosphate (Ca ₃ (PO ₄ ) ₂ ) are produced.
CaO + Na ₂ CO ₃ + H ₂ O → CaCO ₃ + 2NaOH (Formula 1)
CaO + K ₂ CO ₃ + H ₂ O → CaCO ₃ + 2KOH (Formula 2)
CaO + NaHCO ₃ + H ₂ O → CaCO ₃ + 2NaOH (Formula 3)
CaO + H ₂ SO ₄ + (H ₂ O) → CaSO ₄ + H ₂ O (Formula 4)
3CaO + 2H ₃ PO ₄ + (H ₂ O) → Ca ₃ (PO ₄ ) ₂ + 3H ₂ O (Equation 5)
In addition, by using such a treating agent 2, a calcium-containing water-insoluble compound can be generated also for calcium hydroxide (Ca (OH) ₂ ), calcium chloride (CaCl ₂ ), and the like as a calcium-containing component. Furthermore, for the alkaline earth metal components such as magnesium (Mg) and barium (Ba) other than calcium, a water-insoluble compound can be generated by using the treating agent 2 in the same manner.

(Solid-liquid separator)
The cleaning treatment liquid 4a supplied from the cleaning tank 4 is introduced into the solid-liquid separation device 5 and is subjected to solid-liquid separation. Most of the water-insoluble compound and the water-insoluble component in fly ash 1 are separated as solid component 5a, and the water-soluble component in fly ash 1 and a part of treatment agent 2 (the specific component in fly ash 1 (Including the water-soluble component produced by reacting with the liquid component 2) as the liquid component 5b. As the solid-liquid separation device 5, a filter type, a sedimentation type, a centrifugal separation type, or the like can be used, but it is preferable to have a multi-stage solid-liquid separation function. Since solids having various particle sizes coexist in the mixture with the generation of aggregates due to the washing treatment, a high solid-liquid separation function can be ensured by sequentially performing solid-liquid separation treatment. At this time, by setting a particle size range suitable for recovering the water-insoluble compound generated by the reaction, it is possible to select and selectively take out the water-soluble compound. The separated solid component 5a is collected and collected in the solid recovery unit 6, and the separated liquid component 5b is stored in the storage tank 7.

(Evaporation and drying equipment)
The liquid component 5b is introduced into the evaporating and drying device 8, and the liquid component 5b is subjected to an evaporation process of water and the like constituting a main component of the liquid component 5b and a drying process of a dissolved component in the liquid component 5b. This apparatus is characterized in that a heat pump type drying apparatus having high energy efficiency is used as the evaporating and drying apparatus 8. In addition, the heat pump type drying apparatus in the present apparatus is specifically provided on the primary heat exchange section 81 into which the liquid component 5b is introduced, downstream of the primary heat exchange section 81, as illustrated in FIG. The secondary heat exchanging unit 82 has a secondary heat exchanging unit 82 in which evaporation and drying processes are performed under high temperature and reduced pressure conditions.

  Here, in the secondary heat exchange section 82, a part of the liquid component 5b that has become the high-temperature evaporating component 8a is adiabatically compressed by using the compressor 83 to increase the energy, and the secondary heat exchange is performed again as the compressed steam 8c. A more efficient heat pump can be configured by introducing the heat to the heat radiation side of the section 82 and setting the heat absorbing side of the secondary heat exchange section 82 to a reduced pressure condition using the vacuum pump 84. In addition, at the start-up of the evaporating and drying apparatus 8 or at all times, by supplying and adding external steam (for example, boiler steam) 8d from a steam supply source 85 such as a boiler to the compressed steam 8c supply path, The high-temperature condition on the heat radiation side of the secondary heat exchange unit 82 can be quickly secured, and the evaporating and drying device 8 can be quickly started. Here, the heat radiation side of the secondary heat exchange section 82 refers to the pipe body 82a through which the high-temperature compressed steam 8c flows in the pipe in the secondary heat exchange section 82 or a heat transfer section on the surface thereof. In the next heat exchange part 82, it refers to a space 82b that is in contact with the surface of the tube body 82a. Although FIG. 2 illustrates a configuration having one pipe 82a, the configuration is not limited to this, and a configuration in which a large number of pipes are disposed or a configuration in which a surface of the pipe has an uneven portion is provided. Any configuration having an equal heat exchange function can be applied.

  Here, the compressed steam 8c (and the external steam 8d) exchanges heat with the liquid component 5b under reduced pressure conditions in the secondary heat exchange unit 82 to be cooled, and the primary heat exchange unit 81 further reduces the temperature of the low-temperature liquid. It is condensed by heat exchange with the component 5b and taken out as condensed water 8e. On the heat absorption side of the secondary heat exchange unit 82, the dissolved components in the liquid component 5b are dried and solidified as salts, and the dried salts and the like are collected as solidified salts 8b via a salt and the like collecting unit (not shown). Is done. By performing heat exchange on the downstream side of the stock solution flow path under reduced pressure using two-stage heat exchange, the drying process can be performed efficiently. Specifically, for example, in the secondary heat exchanging unit 82, compression at a temperature of 80 to 100 ° C. and a pressure of 100 to 500 kPa (for example, a temperature of 100 ° C. and a pressure of 100 kPa) is performed on the heat radiation side in the evaporating and drying apparatus 8. The steam 8c and / or the external steam 8d are supplied, and the liquid component 5b is supplied under the conditions of the heat absorption side at a temperature of 50 to 80 ° C and a pressure of 30 to 100 kPa (for example, a temperature of 80 ° C and a pressure of 48 kPa).

<Another configuration example of this device>
FIG. 3 shows another configuration example (second configuration example) of the present apparatus. The basic configuration is the same as that of the first configuration example. However, as an additional function, part or all of the recovered evaporating component 8a forms condensed water 8e in the condenser 9 and is used as cleaning water. Characterized by having a return flow path Lr introduced into Except for the water contained in the solid component 5a separated in the solid-liquid separation device 5 or the water containing the crystal water in the solidified salt 8b dried and processed in the evaporating and drying device 8, the transport operation and the decompression operation are performed. Since the amount of discharged water can be limited except for a small loss in the system in the above-described method, a predetermined amount of condensed water 8e can be used. In addition, fly ash is mainly composed of inorganic substances, and since there is almost no other than water and inorganic salts in the liquid component that has been washed and solid-liquid separated, almost no impurities are contained in the evaporated component generated by evaporation to dryness. Not included. Therefore, in the present apparatus, the condensed water 8e is treated in the same manner as the clean water and is used as a part of the wash water 3, so that the amount of the wash water 3 used can be significantly reduced. Furthermore, even if impurities are contained in the evaporating component, by forming such a circulation system, the wastewater discharged to the outside and the impurities are significantly reduced, thereby greatly reducing the load of wastewater treatment. can do.

  Further, the condensed water 8e recovered from the evaporating and drying device 8 is a nearly neutral aqueous solution in which inorganic components including alkaline earth metal components and water-soluble salts are greatly reduced as described above. Therefore, the fly ash 1 has no selectivity to a specific component, and does not affect the water ash 1 rinsing process.

<Fly ash treatment method>
The method of treating fly ash using the present apparatus (hereinafter referred to as “the present method”)
(1) a washing process in which fly ash is mixed and stirred with washing water and a treating agent;
(2) a solid-liquid separation step in which the washed cleaning solution is separated into a solid and a liquid;
(3) an evaporation to dryness step in which water in the liquid component evaporates or is separated;
Having. Hereinafter, each step will be described in detail.

〔Preprocessing〕
In this method, if the fly ash is in a state that can be washed with water, such as incinerated fly ash or molten fly ash, the fly ash is supplied to the washing step as it is, but the fly ash is treated with chelated fly ash or cement solidified. In the case of incinerated ash or the like, it is preferable that the incinerated ash be crushed using a crusher and supplied to the washing step as a powder having a predetermined particle size or less (for example, an average particle size of 200 μm or less). Since such fly ash is a solid having a particle size of several cm to several tens cm or more, the reaction efficiency with the treating agent in the washing process is poor, the surface area is increased by pulverization, and water permeates into the pores. Thereby, high reaction efficiency can be ensured. In addition, sludge incineration ash, soil, and the like, which are difficult to extract by washing with water as they are, are preferably subjected to an acid treatment (for example, with hydrochloric acid or nitric acid) as a pretreatment. Further, in the case where sludge having a large variation in particle size and difficult to clean such as main ash is formed, it is preferable to perform the acid treatment together with the pulverization treatment. Also, when the fly ash contains a large amount of leachate and has a high acidity, or when the acid treatment is performed as described above, a neutralization treatment (for example, with sodium hydroxide or potassium hydroxide) is performed as a pretreatment. Is preferably performed.

(1) Washing step Fly ash that can be washed with water is supplied to a washing tank, mixed and agitated with washing water and an inorganic acid or inorganic salt-based treating agent, and subjected to cleaning treatment and fly ash during the washing process. Reacts with the alkaline earth metal component to form a water insoluble compound. As described above, the type and the supply amount of the washing water and the treatment agent are set according to the type and the treatment amount of the fly ash. In the fly ash cleaning treatment, it is preferable to use several times to several tens times the amount of wash water of fly ash. Most of the alkaline earth metal components contained in the fly ash are insoluble in water by sufficiently stirring for a predetermined time required for dissolving the water-soluble components in the fly ash and for reacting the alkaline earth metal component with the treating agent. Compounds. The amount of the treatment agent to be introduced varies depending on the type of fly ash and the like, but it is preferable that the fly ash be sampled in advance, the content of calcium and the like be measured, and calculated based on the above reaction formulas 1 to 5 and the like. A sufficiently stirred and washed mixture of unreacted fly ash, washing water and a water-insoluble compound (washing treatment solution containing a treating agent) is introduced into a solid-liquid separation device in a solid-liquid mixed state. In addition, as a part of the washing water, an evaporation component generated by an evaporation to dryness process described later is condensed and refluxed to form a circulation system for use, thereby reducing the supply amount of new washing water. it can. Furthermore, extremely high energy efficiency can be ensured by exchanging the heat of the evaporated component to be condensed and refluxed with the liquid component containing salts to be evaporated and dried to be used for the heat treatment.

(2) Solid-Liquid Separation Step The washed cleaning treatment liquid is subjected to solid-liquid separation, the separated solid component is collected, and the separated liquid component is provided. In the present method, it is not necessary to specify the particle size of the solid component to be separated, but it is preferable to separate a solid component, for example, 1.0 μm or more, which does not become a deposit in a later step, to constitute a liquid component. As described above, the solid-liquid separation method is set according to the properties of the fly ash, the type and amount of the water-insoluble component or the water-insoluble compound, and the like. When a multi-stage filter having a solid-liquid separation function is used, solid-liquid separation can be performed efficiently for a long period of time. A solid component having a particle size range suitable for recovering the water-insoluble compound generated by the reaction can be selectively removed. The separated solid component is collected and collected, and then subjected to a drying treatment and the like, and is used as a raw material of cement, such as slaked lime, and can be used as a valuable resource. The separated liquid component 5b is transferred to the evaporating and drying treatment step via the storage tank 7.

(3) Evaporation and Drying Step The separated liquid components are usually once stored and evaporated to dryness in predetermined amounts. The water in the liquid component is evaporated or separated, the dissolved component in the liquid component is recovered, and the evaporated component is condensed and recovered. At this time, by performing the heat pump drying process, it is possible to recover salts having high energy efficiency. In addition, by using the evaporated component in the liquid component as the heat medium of the heat pump and collecting the condensed water generated by the heat exchange, the closed system heat circulates between the high-temperature side heat exchange section and the low-temperature side heat exchange section. As compared with the conventional method using a medium, it is possible to recover salts with higher energy efficiency.

<Verification of this device>
The function of recovering salts and the like in this device is compared with the conventional recovery device for salts and the like (washing treatment without adding a recovery agent such as calcium and evaporation to dryness using a heating plate), and consumption of reagents and the like. The amount and energy consumption were verified.

[Verification conditions]
(I) Using incineration fly ash having an average particle size of about 50 μm, a washing treatment was performed with washing water (city water) in an amount five times that (weight ratio). In this apparatus, sodium carbonate was used as a treating agent.
(Ii) The washing treatment liquid was subjected to a solid-liquid separation treatment using a filter type filter to separate into a liquid component and a solid component, and the solid component was recovered.
(Iii) The liquid component was evaporated to dryness using high-temperature steam (compressed steam or / and combustion steam of a kerosene boiler) to recover a solid salt.
(Iv) The composition of the recovered solidified salt was analyzed.
(V) The running cost was calculated by calculating the amount of kerosene used for the steam generating boiler fuel, the power consumption of the compressor (heat pump) and the amount of sodium carbonate used in (i) to (iii) above.

〔inspection result〕
The verification results as shown in Table 1 were obtained. In this apparatus, it was demonstrated that the water content of the solidified salt can be reduced to 10% or less. In addition, it has been proved that, for the same fly ash processing amount, the effect of reducing energy is particularly high and the cost can be reduced by about 84%. Furthermore, in the conventional apparatus, a deposition residue was found in the treatment system, but not in the present apparatus.

DESCRIPTION OF SYMBOLS 1 Fly ash 2 Treatment agent 3 Cleaning water 4 Cleaning tank 4a Cleaning treatment liquid 41 Stirring means 31 Cleaning water supply unit 5 Solid-liquid separator 5a Solid component 5b Liquid component 6 Solid recovery unit 6a Dry cake 7 Storage tank 8 Evaporation drying device 8a Evaporation component 8b Solidified salt

Claims (5)

A washing tank in which powdery or crushed fly ash, washing water and a treating agent are introduced, and a stirring and washing treatment is performed;
A solid-liquid separation device having a solid recovery section in which a cleaning treatment liquid supplied from the cleaning tank is subjected to solid-liquid separation, and a separated solid component is recovered, and a liquid supply section in which the separated liquid component is supplied. When,
The liquid component is introduced, an evaporation / drying process is performed, and a salt or the like recovery unit for recovering a dissolved component in the liquid component, and a water or the like recovery unit for condensing the evaporated component are provided. And a device,
As the treatment agent, an inorganic acid or an inorganic salt that reacts with the alkaline earth metal component in the fly ash to form a water-insoluble compound,
As the evaporating and drying device, a heat pump type drying device is used, and as a heat medium of the heat pump type drying device, an evaporation component from the liquid component subjected to the evaporation / drying process is used,
The heat pump type drying device is provided downstream of the primary heat exchange section into which the liquid component is introduced, and performs the evaporation and drying of the liquid component under high temperature and reduced pressure conditions. A secondary heat exchange unit, a compressor that adiabatically compresses a vapor component created from a part of the liquid component on the heat absorption side of the secondary heat exchange unit, and introduces the vapor component again to the heat radiation side of the secondary heat exchange unit; Pressure reducing means for reducing the pressure on the heat absorption side of the secondary heat exchange section,
Compressed steam supplied from the heat radiation side of the secondary heat exchange section exchanges heat with the liquid component in the primary heat exchange section and is condensed and taken out as condensed water, and the heat absorption side of the secondary heat exchange section Wherein the dissolved component in the liquid component is dried and solidified as salts and recovered as a solidified salt .   The fly ash processing apparatus according to claim 1, wherein any one of sodium carbonate, potassium carbonate, sodium bicarbonate, sulfuric acid, and phosphoric acid, or a combination thereof is used as the processing agent. The fly ash treatment according to claim 1 or 2 , wherein a part or all of the evaporative components collected in the water etc. recovery part has a return flow path introduced into the cleaning tank as cleaning water. apparatus. The powdered or crushed fly ash is mixed and stirred with washing water and an inorganic acid or inorganic salt-based treating agent, and, together with the washing treatment, reacts the treating agent with an alkaline earth metal component in the fly ash. A washing step in which a water-insoluble compound is formed by
A solid-liquid separation step in which the washed cleaning treatment liquid is subjected to solid-liquid separation, the separated solid component is collected, and the separated liquid component is supplied.
An evaporating and drying step in which water in the liquid component is evaporated or separated, a dissolved component in the liquid component is recovered, and the evaporated component is condensed and recovered.
A heat pump type drying device is used in the evaporating and drying step, and an evaporating component from the liquid component subjected to the evaporating and drying treatment is used as a heat medium of the heat pump type drying device,
The heat pump type drying device is provided downstream of the primary heat exchange section into which the liquid component is introduced, and performs the evaporation and drying of the liquid component under high temperature and reduced pressure conditions. A secondary heat exchange unit, a compressor that adiabatically compresses a vapor component created from a part of the liquid component on the heat absorption side of the secondary heat exchange unit, and introduces the vapor component again to the heat radiation side of the secondary heat exchange unit; Pressure reducing means for reducing the pressure on the heat absorption side of the secondary heat exchange section,
Compressed steam supplied from the heat radiation side of the secondary heat exchange section exchanges heat with the liquid component in the primary heat exchange section and is condensed and taken out as condensed water, and the heat absorption side of the secondary heat exchange section Wherein the dissolved component in the liquid component is dried and solidified as salts and recovered as a solidified salt . The fly ash according to claim 4 , wherein a heat pump type drying process is performed in the evaporating and drying step, and a part or all of the collected evaporating components are used as washing water in the washing step. Processing method.

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