JPH05184860A - Method for solidifying byproduct of wet type line-gypsum flue gas desulfurizer - Google Patents

Abstract

PURPOSE:To produce a formed solidified body as semifinished products from a concentrated slurry by concentrating absorbent slurry drawn out from a wet type lime-gypsum flue gas desulfurizer, kneading the concentrated slurry, fly ash and quicklime to form a formed body, and drying and solidifying the formed body by heating air unsaturated with moisture produced by recovery heat from flue gas. CONSTITUTION:Absorbent slurry drawn out from a wet type lime-gypsum flue gas desulfurizer is concentrated by a slurry concentrator 13. The concentrated slurry whose main component is gypsum, fly ash 18 and quicklime or slaked lime 19 are kneaded in a kneading tank 20 to form a formed body in a forming tank 21. On the other hand, heating air unsaturated with moisture 31 produced by heat recovered from untreated gas 1 by a heat recovery unit 30 is fed to a curing dryer 22 to dry and solidify the formed body. As a result, formed solidified bodies usable for building materials are produced from the concentrated slurry and gypsum or fly ash which have a tendency to be surplus heretofere depending on market conditions is made utilized effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating after-absorption extracted slurry in a wet lime gypsum method flue gas desulfurization apparatus,
The present invention relates to a method for producing a solidified body that can be used as a building material.

[0002]

2. Description of the Related Art One mode of a conventional wet lime gypsum method flue gas desulfurization apparatus will be described with reference to FIG. In FIG. 2, the absorption tower 1
The untreated exhaust gas 101 introduced into 02 is desulfurized by contact with the circulating absorption slurry sprayed from the spray pipe 106 above the absorption tower 102 by the pump 105, and the purified exhaust gas 107
Is discharged as. The SO ₂ absorbed from the exhaust gas was absorbed by the circulating absorption slurry flowing down to the circulation tank 103 by absorbing SO _2.
2 is contained as sulfite, and in order to oxidize this sulfite to form gypsum, air 1 is placed at the bottom of the circulation tank 103.
04 is blown. On the other hand, the circulation tank 103 is supplied with the limestone slurry absorbent corresponding to the stoichiometric amount of the absorbed SO _{2 through} the pipe 111, and the amount of the circulation absorption slurry corresponding to the supplied amount is extracted through the pipe 112 and solid-liquid. Solid-liquid separation is performed by the separator 113. The solid-liquid separation operation separates the solid phase 114 whose main component is gypsum and the filtrate, a part of the filtrate is sent from the pipe 110 to the limestone slurry storage tank 108 for adjusting the limestone slurry, and the rest is sent from the pipe 115. It is extracted as wastewater to the wastewater treatment process 116 outside the system.

[0003]

Although the conventional examples have been concretely described above, the solid of the main component gypsum, which is a by-product of solid-liquid separation in the conventional examples, is supplied to the market as a raw material for gypsum board, cement and the like. However, due to conditions such as changes in social conditions or location environment, supply and demand cannot be balanced, and surplus byproduct gypsum must be dumped in landfills, and stable market development is desired.

Further, in the case of coal burning, a large amount of fly ash is produced as a combustion residue, and although some of this fly ash can be expected as a raw material for fly ash cement in the market, most of it is actually dumped in landfill. ,
In some areas, securing landfill sites for these by-product gypsum and fly ash is regarded as a problem, and there is a strong demand for application development that can expect a stable market.

The present invention is intended to provide a useful method for making a by-product from a wet lime gypsum method flue gas desulfurization apparatus which can meet the above-mentioned state of the art and the above-mentioned demand into a product which can be utilized as a building material.

[0006]

According to the present invention, an absorbent slurry extracted from a wet lime gypsum method flue gas desulfurization apparatus is concentrated, and a concentrated slurry containing gypsum as a main component is kneaded with fly ash and quick lime or slaked lime. A method for solidifying a by-product of a wet lime gypsum method flue gas desulfurization apparatus, which comprises drying and solidifying a molded article molded by the above method with heated water unsaturated unsaturated water generated by heat recovered from flue gas.

In the present invention, the mixing ratio of concentrated slurry (gypsum: dry basis): fly ash: quick lime is about 25-40: 40-65: 6-20 by weight.

Various methods can be considered for the moisture-unsaturated heated air generated by the heat recovered from the flue gas. The recovered heat from the flue gas heats water and air to generate heated water and heated air. Then, these are brought into contact with each other to first generate moisture-saturated heated air, and the heated air is mixed with the moisture-saturated heated air to generate moisture-unsaturated heated air.

[0009]

According to the present invention, as described above, after the concentrated slurry of the circulating absorption slurry produced as a by-product, fly ash and quick lime or slaked lime are kneaded and molded, the saturated heat of moisture is utilized by utilizing the heat recovered from the flue gas. Heated air is produced into air, and these are mixed to form heated air with a slightly unsaturated water content, and this is used as a drying medium to dry the above kneaded molded product at a moderate speed to finally obtain a molded solidified product as a semi-finished product. It is a by-product.

[0010]

EXAMPLE One embodiment of the present invention will be specifically described with reference to FIG. In FIG. 1, the untreated exhaust gas 1 introduced into the absorption tower 2 is pumped by a spray pipe 6 above the absorption tower 2 by a pump 5.
It is desulfurized by coming into contact with the circulating absorption slurry sprayed from and is discharged as clean exhaust gas 7. The circulating absorption slurry that absorbed SO ₂ from the exhaust gas and flowed down to the circulation tank 3 contained the absorbed SO ₂ as sulfite, and the bottom of the circulation tank 3 is located at the bottom of the circulation tank 3 in order to oxidize this sulfite to form gypsum. Air 4
Is blown in.

On the other hand, the circulation tank 3 is supplied with a limestone slurry absorbent corresponding to the stoichiometric amount of absorbed SO ₂ from the pipe 11, and the amount of the circulation absorption slurry corresponding to the supplied amount is extracted from the pipe 12. The concentrated slurry is sent to the kneading tank 20 through the pipe 17, while most of the diluted slurry is returned to the limestone slurry storage tank 8 through the pipe 10 and the remainder is concentrated to avoid impurities. Therefore, the waste water is extracted from the pipe 15 to the waste water treatment process 16. In addition to the concentrated slurry, fly ash 18 and quick lime or slaked lime 19 are supplied to the kneading tank 20, which are sufficiently mixed and kneaded in the kneading tank 20 and then a molding machine 21.
Sent to and molded. The formed kneaded product is then sent to the curing dryer 22.

On the other hand, the heat recovered from the untreated exhaust gas 1 by the heat recovery device 30 is passed through the heat medium circulation pipe 25 to the air heater 29.
And the moisture-saturated air generator 26, and the supplied heat is exchanged with the air 28 in the air heater 29 and with the water 27 and the heated air 24 in the moisture-saturated heated air generator 26, respectively, and then the air The air 3 having a slightly unsaturated water content is obtained by mixing the heated air 24 produced by the heater 29 with the moisture saturated heated air 23 produced by the water saturated air generator 26.
1 and None Supply to the curing dryer 22. Curing dryer 2
In No. 2, the water-unsaturated heated air 31 is supplied for a predetermined time according to the size of the molded product, and after curing and drying for a predetermined time, the molded solidified body 33 as a by-product is recovered as a product.

Although the present invention has been described in detail above, a part or most of the exhaust 32 from the curing dryer 22 may be circulated to the moisture saturated heated air generator 26.

The present invention will be described in more detail with reference to a specific embodiment having the form shown in FIG.

(Example) Temperature is 180 ° C., SO ₂ is 14
In the wet limestone gypsum method flue gas desulfurization apparatus for treating 50 ppm of untreated exhaust gas 1 at 8000 m ³ N per hour, a heat recovery unit 30
The air 28 of 500 m ³ N per hour is heated to 60 ° C. by utilizing the heat recovered in step 1, and 80% of the air 28 is supplied to the moisture saturated heating air generator 26 to form the moisture saturated heating air 23 of 60 ° C. Curing dryer 2 mixed with the rest of heated air 24
Feed to 2.

On the other hand, from the slurry concentrator 13, 25 kg / h of concentrated slurry having a solid content of about 40% (based on dry solid content)
Then, 50 kg of fly ash 18 and 8 kg of quicklime 19 were further supplied to the kneading machine 20.
What is kneaded by the kneading machine 20 is 4 × 4 × 1 by the molding machine 21.
It was molded into a 6 cm size and supplied to the curing dryer 22. The molded and solidified body was taken out after being cured and dried by the curing and drying device 22 for about 3 days. The molded solidified product taken out from the curing dryer 22 was cut into a 4 cm cube and the compression strength was measured. As a result, it was 130 kgf / cm ² or more. This value has a strength equivalent to that of building materials such as bricks, and it is judged that it can be used as a building material.

[0017]

As described above, according to the present invention, a molded solidified body usable as a building material can be produced from a slurry containing gypsum as a main component, which is a by-product of a wet lime gypsum method flue gas desulfurization apparatus. It is now possible to effectively use plaster or fly ash, which in the past may have been a little surplus depending on the market situation.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a mode example according to an embodiment of the present invention.

FIG. 2 is an explanatory view of one mode of a wet limestone gypsum method flue gas desulfurization apparatus in a conventional example.

Claims (1)

[Claims] 1. A molded product obtained by concentrating an absorbing slurry extracted from a wet lime gypsum method flue gas desulfurization device, kneading the concentrated slurry containing the gypsum as a main component, fly ash, and quick lime or slaked lime, and molding the mixture. A method for solidifying a by-product of a wet limestone gypsum method flue gas desulfurization apparatus, characterized by drying and solidifying by heated moisture powder saturated heat generated by heat recovered from flue gas.