JPH11281040A - Apparatus and method for treating incineration ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover salts efficiently and economically without the necessity of a special heat source by using a compact and simple facility. SOLUTION: A refuse ash treating apparatus 1 comprises an ash melting furnace 3 for heating and melting a refuse ash (a), a heat recovering unit 8 for recovering heat of an exhaust gas G1 generated from the ash melting furnace 3 and separating a molten fly ash (b) therefrom, a dust collector 12 for collecting the molten fly ash (b) in the exhaust gas discharged from the heat recovering unit 8, a wet type detoxicating treatment device 16 for adding water (k) and a pharmaceutical agent (i) to the molten ash (b) separated and collected by the heat recovering unit 8 and the dust collector 12, respectively, for separation into heavy metals (c) and an aqueous solution (d) containing salts. The apparatus further comprises an evaporating tower 21 for evaporating and solidifying the aqueous solution (d) containing salts by blowing an exhaust gas G3 which has been obtained by heating an exhaust gas G2 discharged from the dust collector 12 with the use of a heat exchanger 9 provided at the heat recovering unit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incineration ash treatment apparatus and an incineration ash treatment method for treating incineration ash containing heavy metals and salts generated when incinerated materials are incinerated.

[0002]

2. Description of the Related Art In recent years, an incineration ash treatment apparatus or an incineration ash treatment method for treating incineration ash containing heavy metals and salts generated when incinerated materials are incinerated, for example, refuse ash generated when municipal solid waste is incinerated. In a refuse ash treatment apparatus or refuse ash treatment method for treating ash, an apparatus or a method for melting refuse ash for the purpose of extending the life of a landfill site by reducing the volume of refuse ash and detoxifying the refuse ash is rapidly spreading.

FIG. 2 is a system diagram showing an example of a conventional refuse ash treatment apparatus. In the conventional refuse ash treatment device 2, refuse ash a supplied to the ash melting furnace 3 is heated and melted at a temperature of 1,000 ° C. or more by the combustion heat of the air f and the fuel e supplied at the same time, thereby reducing the volume. It is discharged from the furnace bottom as slag g which has been converted and made harmless. The refuse ash a contains several tens% of low-boiling substances, mainly chlorides of alkali metals, which are volatilized by high heat during melting to become gas. Other lead is also sent to the heat recovery unit 8 through a pipe 30a with the high temperature exhaust gas G ₁ of 1,000～1,400 ° C. Low-boiling heavy metals and volatilizes simultaneously ash melting furnace 3, such as cadmium.

The high-temperature exhaust gas G ₁ discharged from the ash melting furnace 3
Is cooled to a temperature at which the heat collector 8 can withstand the dust collector 12 at the subsequent stage, for example, about 200 to 250 ° C. in the case of a bag filter. At this time, the exhaust gas G
_The gaseous chlorides and low-boiling heavy metals contained in ₁ are condensed and solidified again and become dust in the exhaust gas. These gaseous fine dust ash a of chloride and low boiling substance entrained in the exhaust gas G ₁ flyaway in the dust and ash melting furnace 3 solidification, or settled to the bottom of the heat recovery section 8 as a so-called molten fly ash b The dust is collected (or collected) by the dust collector 12 further downstream. These molten fly ash b are collected in the molten fly hopper 14 through the pipe 30b. The molten fly ash b collected in the molten fly ash hopper 14 is sent to the wet detoxification processing device 16.
Note that reference numeral 26 denotes an exhaust fan for discharging exhaust gas from the dust collector 12, and reference numeral 28 denotes a chimney.

[0005] In the wet detoxification treatment device 16, a chemical i for detoxifying heavy metals contained in the molten fly ash b, for example, a chelating agent is added through a pipe 30c. Furthermore,
Water h is supplied through the pipe 30d. Almost all the chloride contained in the molten fly ash b is dissolved in the water h supplied through the pipe 30d because it is a water-soluble substance, and is sent to the water treatment apparatus 19 through the pipe 30e. Heavy metals contained in the molten fly ash b are rendered harmless by the chemical i supplied through the pipe 30c, and are precipitated and discharged as solid sludge c.

As the water treatment device 19, an electrolysis system or a reverse osmosis membrane system is adopted. Here, high-concentration salts j dissolved in wastewater sent through a pipe 30e are separated and discharged as solid chlorides. Is done. The water h containing (in short, purified) low-concentration salts from which the salts j have been separated is sent again to the wet detoxification apparatus 16 through the pipe 30d, and dissolves the molten fly ash b sent from the molten fly ash hopper 14. Used for Also, make-up water is supplied to this wet processing system from the pipe 30k.

[0007]

However, the conventional refuse ash treatment apparatus 2 has the following problems. That is, when the electrolysis method is adopted as the water treatment apparatus 19, the equipment becomes large and cannot be installed depending on the location conditions, and the equipment cost and the power cost are high, and the equipment is complicated.

When the reverse osmosis membrane system is adopted as the water treatment device 19, the equipment cost is high, and the operating costs of the pump and the like are high.

Therefore, in the conventional refuse ash treatment apparatus 2, it is necessary to solve the problem that the equipment is large, the equipment cost, the power cost, the operation cost, etc. are high, and the equipment is complicated. .

An object of the present invention is to provide an incineration ash treatment apparatus and an incineration ash treatment method for treating incineration ash containing heavy metals and salts generated when incinerated objects are incinerated, which is compact and simple in terms of equipment. It is possible to efficiently and economically recover salts without requiring a special heat source.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an ash melting furnace for heating and melting incinerated ash containing heavy metals and salts generated when incinerated objects are incinerated; Heat recovery and separation means for recovering the heat of the exhaust gas generated in the melting furnace and separating fly ash in the exhaust gas, and fly ash collection for collecting fly ash in the exhaust gas discharged from the heat recovery and separation means And incineration processing and separation means for adding water and chemicals to the fly ash separated or collected by the heat recovery separation means and fly ash dust collection means to separate the fly ash into an aqueous solution containing heavy metals and salts. The ash treatment device is provided with an evaporative solidification means for evaporating and solidifying the aqueous solution containing salts separated by the treatment / separation means using the heat recovered by the heat recovery / separation means.

Since the exhaust gas from the ash melting furnace is discharged at a high temperature of more than 1,000 hundreds of degrees Celsius, even if the heat is recovered as steam by the heat recovery and separation means, there is still a surplus. The aqueous solution containing salt (waste water) is heated and evaporated to recover the salt as a solid. By providing the evaporative solidification means using the heat recovered by the heat recovery and separation means, it is possible to provide a simple and simple salt recovery apparatus with equipment, and to utilize the heat recovered by the heat recovery and separation means. Therefore, no special heat source is required, and the salt can be efficiently and economically recovered.

Further, in the above incineration ash treatment apparatus, the evaporative solidification of the evaporative solidification means is heated by passing exhaust gas discharged from the fly ash dust collection means through a heat exchanger provided in the heat recovery and separation means. This is performed by blowing exhaust gas.

According to the incineration ash treatment apparatus of the present invention, in addition to the operation of the incineration ash treatment apparatus of the above invention, since the exhaust gas discharged from the fly ash dust collecting means has a somewhat high temperature, this exhaust gas is used as heat recovery and separation means. The temperature can be easily raised by passing through a heat exchanger, and the aqueous solution containing salts is quickly evaporated and solidified.

Further, the incinerated ash containing heavy metals and salts generated when the incinerated material is incinerated is heated and melted, the fly ash in the generated exhaust gas is separated, and water and a chemical are added to the fly ash. In the incineration ash treatment method of separating the heavy metals and salts by an aqueous solution containing heavy metals and salts, the heat incineration ash is heated and melted to contain the salts. To evaporate and solidify the aqueous solution and recover it as solid salts.

Since the aqueous solution containing salts is evaporated and solidified by utilizing the heat generated when the incinerated ash is heated and melted, the salts can be easily recovered, and the efficiency can be improved without requiring a special heat source. It is possible to collect salts economically and economically.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an incineration ash treatment apparatus and an incineration ash treatment method according to the present invention will be described below with reference to FIG.

FIG. 1 is a system diagram showing one embodiment of an incineration ash treatment apparatus according to the present invention. The refuse ash treatment device 1 as an embodiment of the incineration ash treatment device of the present invention includes an ash melting furnace 3 for heating and melting refuse ash a (incineration ash) generated when incinerating refuse as refuse. , while recovering heat exhaust gas G ₁ generated by the ash melting furnace 3, the heat recovery section 8 as a heat recovery fractionation means for separating the molten fly ash b in the exhaust gas G _1, from the heat recovery unit 8 A dust collector 12 as fly ash dust collecting means for collecting the molten fly ash b in the discharged exhaust gas, and water is added to the molten fly ash b separated or collected by the heat recovery unit 8 and the dust collector 12. Wet detoxification treatment apparatus 1 as treatment separation means for adding a chemical and separating it into an aqueous solution containing heavy metals and salts
6 is provided. Then, an evaporating tower 21 is provided as evaporating and solidifying means for evaporating and solidifying the aqueous solution d containing salts separated by the wet detoxifying apparatus 16 using the heat recovered by the heat recovery unit 8. Here, the evaporation solidification of the evaporation tower 21, is carried out by blowing the exhaust gas G ₃ which is heated by passing the exhaust gas G ₂ discharged from the dust collector 12 to the heat exchanger 9 provided in the heat recovery section 8 .

More specifically, the refuse ash a supplied to the ash melting furnace 3 is heated and melted to 1,000 ° C. or more by the heat of combustion of the air f and the fuel e supplied at the same time, thereby reducing the volume and detoxifying the ash. The slag g is discharged from the furnace bottom.
The refuse ash a contains several tens% of low-boiling substances, mainly chlorides of alkali metals, which are volatilized by high heat during melting to become gas. In addition, low-boiling heavy metals such as lead and cadmium volatilize at the same time and exhaust gas G from the ash melting furnace
₁ (1,000 to 1,400 ° C.) and sent to the heat recovery unit 8 through the pipe 30a.

The high-temperature exhaust gas G ₁ is heated to a temperature at which the latter-stage dust collector 12 can withstand in the heat recovery unit 8, for example, 20 ° C. when a bag filter is used as the latter-stage dust collector 12.
Heat is recovered to about 0 to 250 ° C. and cooled. At this time, gaseous chloride contained in the exhaust gas G ₁ volatilized in ash melting furnace 3 and the low-boiling heavy metals recondensed, the solidified dust.
These fine dust ash a entrained in the exhaust gas G ₁ flyaway in dust and ash melting furnace in which the lower boiling point material is coagulated or settled to the bottom of the heat recovery section 8 as a so-called molten fly ash b, downstream of the dust collector 12 Dust is collected (or collected) by the. These molten fly ash b are collected in the molten fly hopper 14 through the pipe 30b. The molten fly ash b collected in the molten fly ash hopper 14 is sent to the wet detoxification processing device 16.

In the wet detoxification processing unit 16, a chemical i for detoxifying heavy metals contained in the molten fly ash b, for example, a chelating agent is added through a pipe 30c. Further, water h is supplied through the pipe 30d, and almost all chlorides contained in the molten fly ash b are dissolved in the water h because they are water-soluble substances, and are sent to the evaporation tower 21 through the pipe 30e.

By the way, the clean exhaust gas G ₂ from which dust (melted fly ash b) has been removed by the dust collector 12 is 200 to 200 μm.
Since the temperature is 250 ° C., the evaporating tower 2 evaporates the aqueous solution d containing salts (salt-containing wastewater) sent through the pipe 30e.
If the gas is blown directly into the exhaust gas 1, the temperature of the exhaust gas will be 140 ° C. or less, causing dew condensation in the flue. In an extreme case, the buoyancy required for exhausting the smoke will be insufficient. To avoid this, low temperature exhaust gas G ₂ the pipe 3 at a temperature of 200 to 250 ° C. of the dust collector 12 outlet
It passes through a heat exchanger 9 provided in the heat recovery unit 8 via 0f.

The exhaust gas G ₃ passed through the heat exchanger 9 is 40
The exhaust gas G ₃ is heated to about 0 ° C. and heated, and the
1, the aqueous solution d containing salts sprayed and sprayed from the wet detoxification apparatus 16 is discharged from the evaporating tower 21.
And the chlorides turn into fine solid salts. This fine salt is collected in another downstream dust collector 24, and is collected by the dust collector 24.
Harmful heavy metal-free solid powder salts j from the bottom
Will be collected as In addition, about 4
The exhaust gas G _{3 at} 00 ° C. is deprived of heat by the vaporization of the aqueous solution d containing salts, becomes exhaust gas G _{4 at} about 140 ° C., the salt j is collected by the dust collector 24, and the smoke is exhausted from the chimney 28 by the exhaust fan 26. Is done.

The refuse ash treatment apparatus 1 of the present embodiment is provided with the evaporating tower 21 utilizing the heat recovered by the heat recovery section 8, so that the apparatus can be made compact and simple in terms of facilities. In addition, it is possible to reduce equipment costs, power costs, and operation costs of the apparatus. Further, the salt can be efficiently and economically recovered without requiring a special heat source.

Further, the exhaust gas G discharged from the dust collector 12
_2, since a certain degree temperature is high, the exhaust gas G ₂ a can be increased easily temperature by passage through heat exchanger 9 of the heat recovery unit, high including the concentration of aqueous salt solution d (wastewater) the exhaust gas G _{It is possible} to vaporize using the heat of ( ₃ ) and quickly evaporate and solidify using its own waste heat without using complicated and expensive equipment.

In the refuse ash treatment apparatus 1 of the above embodiment, a heat exchanger 9 is provided in the heat recovery section 3, and the exhaust gas G ₂ at 200 to 250 ° C. discharged from the dust collector 12 is passed through the heat exchanger 9. heating, evaporation tower 21 as an exhaust gas G ₃ of about 400 ° C.
But without providing the heat exchanger 9 in the heat recovery section 3,
The dust collector 12 provided separately from the gas heater has been the exhaust gas G ₂ discharged from the (not shown), heated to about 400 ° C., warmed may be blown into the evaporation tower 21.

Next, the waste ash treatment method of the present embodiment will be described with reference to FIG. Waste ash treatment method of this embodiment, by heating the dust ash a generated when incinerated waste melt, fractionating melt fly ash b in the exhaust gas G ₁ generated,
Water h and chemicals i are added to the molten fly ash b to separate them into sludge c containing heavy metals and aqueous solution d containing salts, and these heavy metals and salts are respectively recovered. Furthermore,
An aqueous solution d containing salts is evaporated and solidified by utilizing heat generated when the refuse ash a is heated and melted, and collected as solid salts j. Since the aqueous solution d containing salts is evaporated and solidified using the heat generated when the refuse ash a is heated and melted, the salts j can be easily recovered as solid powder, and a special heat source is used. The salt j can be efficiently and economically recovered without the need.

[0028]

According to the incineration ash treatment apparatus or the incineration ash treatment method of the present invention, the equipment is compact and simple, and the salt can be efficiently and economically recovered without a special heat source. I can do it.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an incineration ash treatment device according to the present invention.

FIG. 2 is a system diagram showing an example of a refuse ash treatment device according to the related art.

[Explanation of symbols]

DESCRIPTION OF REFERENCE SYMBOLS 1 Waste ash treatment device (incineration ash treatment device) 3 Ash melting furnace 8 Heat recovery unit (heat recovery separation means) 9 Heat exchanger 12 Dust collector (fly ash dust collection means) 16 Wet detoxification processing device (treatment separation means) 21) Evaporation tower (evaporation solidification means) G ₁ Exhaust gas generated in ash melting furnace G ₂ Exhaust gas discharged from dust collector G ₃ Exhaust gas heated by heat exchanger a Waste ash (incinerated ash) b Melt fly ash c Sludge containing heavy metals d Aqueous solution containing salts h Water i Drug j Salts

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideharu Mori 1-2-10 Isogo, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Babcock Hitachi, Ltd. Yokohama Engineering Center

Claims (3)

[Claims] 1. An ash melting furnace for heating and melting incinerated ash containing heavy metals and salts generated when incinerated objects are incinerated, and recovering heat of exhaust gas generated in the ash melting furnace. Heat recovery separation means for separating fly ash in exhaust gas,
Fly ash dust collecting means for collecting fly ash in the exhaust gas discharged from the heat recovery and separating means, and water and chemicals to fly ash separated or collected by the heat recovery and separating means and fly ash dust collecting means. In addition, in an incineration ash treatment device provided with a treatment separation means for separating heavy metals and an aqueous solution containing salts, the salt separated by the treatment separation means using heat recovered by the heat recovery separation means An incineration ash treatment device comprising an evaporating and solidifying means for evaporating and solidifying an aqueous solution containing. 2. The evaporating and solidifying means according to claim 1, wherein the evaporating and solidifying means comprises an exhaust gas heated by passing an exhaust gas discharged from the fly ash dust collecting means through a heat exchanger provided in the heat recovery and separating means. The incineration ash treatment device characterized by performing by blowing air. 3. An incinerated ash containing heavy metals and salts generated when the incinerated material is incinerated is heated and melted, fly ash in the generated exhaust gas is separated, and water and a chemical are added to the fly ash. In the incineration ash treatment method of separating the heavy metals and salts by an aqueous solution containing heavy metals and salts, the heat incineration ash is heated and melted to contain the salts. A method for treating incineration ash, comprising evaporating and solidifying an aqueous solution and recovering it as solid salts.