JP6977790B2 - Reducing agent manufacturing equipment - Google Patents

Description

The present disclosure relates to an apparatus for producing a reducing agent.

Hexavalent chromium contained in wastewater and soil is harmful to the human body such as causing allergic symptoms, so the content is specified as 0.05 mg / L or less in water quality standards. Hexavalent chromium is known to be reduced by a reducing agent and converted into harmless trivalent chromium. As a method for producing calcium sulfite, which is a kind of reducing agent, a method of liquid-phase reaction between sodium sulfite and calcium chloride is known (see, for example, Patent Document 1). However, reducing agents such as calcium sulfite are generally expensive.

Japanese Unexamined Patent Publication No. 7-215718

In a normal flue gas desulfurization device, sulfur dioxide gas contained in exhaust gas is absorbed by an alkaline solution and recovered as gypsum. It is possible that sulfites are produced during the recovery process, but sulfites are easily oxidized and quickly turn into gypsum. Therefore, it is difficult to stably produce sulfites in high yield by such a method.

Therefore, the present disclosure provides an apparatus for producing a reducing agent capable of inexpensively and stably producing a reducing agent containing a sulfite.

The reducing material manufacturing apparatus according to one aspect of the present disclosure has an introduction port for a raw material gas containing sulfur dioxide and an outlet for discharging an exhaust gas having a concentration of sulfur dioxide lower than that of the raw material gas, and has an alkaline compound and water. An absorption unit that brings the containing alkaline slurry into contact with the raw material gas to absorb sulfur dioxide into the alkaline slurry, and a reaction unit that reacts the alkaline compound with sulfur dioxide to generate a reducing material slurry containing a sulfite. A circulation line that circulates the reducing material slurry that stays in the reaction part to the absorption part, a nozzle that sprays the reducing material slurry that is circulated in the circulation line into the absorption part, and a cooling part that cools the reducing material slurry that stays in the reaction part. , Equipped with.

In the above manufacturing apparatus, a raw material gas containing sulfur dioxide is introduced into the absorption unit. Such a raw material gas can be obtained at a low cost because, for example, exhaust gas from various combustion facilities can be used. Further, since it is provided with a circulation line for circulating the reducing agent slurry containing the sulfite generated in the reaction section and a nozzle for spraying the reducing agent slurry into the absorbing section, the sulfite is sufficiently contained in the reducing agent slurry. Can be concentrated. Further, since the cooling unit for cooling the reducing agent slurry is provided, it is possible to prevent the sulfite contained in the reducing agent slurry from changing to gypsum. Therefore, the above-mentioned production apparatus can inexpensively and stably produce a reducing agent containing a sulfite.

In the above manufacturing apparatus, the temperature of the raw material gas introduced into the absorption unit may be controlled to 50 to 400 ° C., and the temperature of the reducing agent slurry staying in the reaction unit may be controlled to 70 ° C. or lower. By controlling to such a temperature range, sulfites can be efficiently produced.

The manufacturing apparatus has an alkaline slurry tank that mixes an alkaline compound and water to produce an alkaline slurry, a lead-out line that draws out the reducing material slurry that stays in the reaction section, and a reducing material slurry that is drawn out from the reaction section. It may be provided with a reducing material slurry tank to be stored. As a result, the reducing agent can be continuously produced, and the reducing agent can be produced at a lower cost.

The alkaline compound may contain at least one selected from the group consisting of carbonates of alkaline earth metals, hydroxides of alkaline earth metals, carbonates of alkali metals, and hydroxides of alkali metals. This makes it possible to efficiently generate sulfites.

The reducing agent slurry may contain at least one sulfite of an alkaline earth metal and an alkali metal. Since such sulfites are sufficiently excellent in reactivity, their performance as a reducing agent can be further enhanced. The reducing agent slurry may contain at least one of an alkaline earth metal and an alkali metal bisulfite. By containing hydrogen sulfite, the elution of hexavalent chromium can be further suppressed.

_{The SO 2} concentration of the raw material gas at the inlet may be 200 to 100,000 ppm. The raw material gas having such an SO ₂ concentration can be easily obtained at a factory or the like. By using such a raw material gas, a reducing agent having a sufficiently high sulfurous acid salt content can be obtained.

The manufacturing apparatus may be provided with equipment for blowing a gas containing oxygen into the reducing agent slurry retained in the reaction section. The flow rate of the gas containing oxygen blown into the reducing agent slurry staying in the reaction unit may be 10% by volume or less based on the flow rate of the raw material gas introduced from the introduction port. As a result, it is possible to suppress the oxidation of the produced sulfite. Further, by controlling the flow rate of the gas containing oxygen, it is possible to control the ratio of the reducing agent and the sulfate.

_{The SO 2} concentration of the exhaust gas at the outlet of the manufacturing apparatus is 0.1 to 3000 ppm, and an absorption unit that brings the exhaust gas into contact with the alkaline slurry may be further provided. This makes it possible to further increase the yield of the reducing agent containing sulfites.

According to the present disclosure, it is possible to provide an apparatus for producing a reducing agent capable of inexpensively and stably producing a reducing agent containing a sulfite.

FIG. 1 is a diagram showing an embodiment of a reducing agent manufacturing apparatus. FIG. 2 is a diagram showing another embodiment of the reducing agent manufacturing apparatus.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings as the case may be. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and duplicate description may be omitted in some cases. In addition, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratio of each element is not limited to the ratio shown in the figure.

FIG. 1 is a diagram showing an embodiment of a reducing agent manufacturing apparatus. The manufacturing apparatus 100 of FIG. 1 has an alkaline slurry tank 30 for producing an alkaline slurry by mixing an alkaline compound and water, an absorption unit 11a and a reaction unit 11b, and prepares a reducing material slurry from the raw material gas and the alkaline slurry. A slurry preparation column 11 to be used, a circulation line 12 for circulating the reducing material slurry staying in the reaction unit 11b to the absorbing unit 11a, and a nozzle 14 for spraying the reducing material slurry circulated in the circulation line 12 into the absorbing unit 11a. A derivation line 15 for deriving the reduction material slurry, a reduction material slurry tank 20 for storing the reduction material slurry derived in the derivation line 15, a water content adjusting unit 40 for reducing the water content contained in the reduction material slurry, and a reduction material slurry. A cooling unit 50 for cooling the slurry is provided.

The alkaline slurry stored in the alkaline slurry tank 30 is produced by mixing an alkaline compound and water. The concentration of the alkaline compound in the alkaline slurry is, for example, 5 to 25% by mass, preferably 10 to 20% by mass, and more preferably 15 to 20% by mass.

The alkaline compound contained in the alkaline slurry contains at least one selected from the group consisting of carbonates of alkaline earth metals, hydroxides of alkaline earth metals, carbonates of alkali metals, and hydroxides of alkali metals. It's fine. As a result, sulfites can be efficiently produced. Preferred alkaline earth metals include calcium and magnesium, and preferred alkali metals include sodium and potassium.

The amount of the alkaline slurry supplied from the alkaline slurry tank 30 to the absorption unit 11a may be adjusted according to the pH of the reducing agent slurry. When the pH value of the reducing agent slurry in the absorption unit 11a or the circulation line 12 becomes equal to or lower than the lower limit, control may be performed to start or increase the supply amount of the alkaline slurry to the absorption unit 11a. On the other hand, when the pH value of the reducing agent slurry becomes equal to or higher than the upper limit value, control may be performed to stop or reduce the supply amount of the alkaline slurry to the absorption unit 11a. Thereby, the pH of the reducing agent slurry can be adjusted to a predetermined range.

_{The SO 2} concentration in the raw material gas is 200 to 100,000 ppm. _{The lower limit of the SO 2} concentration in the raw material gas is preferably 500 ppm, more preferably 1000 ppm, still more preferably 2000 ppm, and particularly preferably 3000 ppm. _{The upper limit of the SO 2} concentration in the raw material gas is preferably 50,000 ppm, more preferably 30,000 ppm, and even more preferably 20,000 ppm. When the SO ₂ concentration is lower than the lower limit, the efficiency of producing a reducing agent (sulfite, etc.) decreases, and the proportion of gypsum having no reducing effect tends to increase. On the other hand, when the SO ₂ concentration exceeds the upper limit, _{the absorption efficiency of SO 2 contained in the raw material gas tends to decrease, and the amount of SO 2} discharged from the gas discharge line 17 tends to increase. The concentration of sulfur dioxide (SO ₂ ) in the present disclosure is a volume-based (standard temperature) concentration, and can be measured using a commercially available measuring device.

The manufacturing apparatus 100 may have a control unit that controls the temperature of the raw material gas. The control unit cools the raw material gas by the gas cooling unit based on the temperature signal of the raw material gas measured by the temperature measuring unit of the raw material gas. The gas cooling unit may be one that cools the raw material gas by an air-cooled type or a water-cooled type on the upstream side of the introduction port 16, and may be one that introduces air into the raw material gas to cool the raw material gas. More specifically, it may have a facility for sprinkling water on the piping through which the raw material gas flows. By controlling the temperature of the raw material gas, it is possible to increase the absorption efficiency of the alkaline slurry and further increase the content of sulfites in the reducing agent.

The raw material gas may be, for example, an exhaust gas generated from a cement clinker manufacturing facility, or may be an exhaust gas generated from a thermal power generation facility. A gas containing sulfur dioxide can be used as a raw material gas. When the concentration of sulfur dioxide is low, the concentration may be adjusted by mixing a cylinder of sulfur dioxide with a high concentration of sulfur dioxide. The temperature of the raw material gas introduced from the introduction port 16 to the absorption unit 11a may be, for example, 50 to 400 ° C. The lower limit of the temperature of the raw material gas is preferably 80 ° C., more preferably 100 ° C. The upper limit of the temperature of the raw material gas is preferably 350 ° C., more preferably 300 ° C., and even more preferably 250 ° C. At such a temperature, it becomes easy to adjust the temperature of the sulfurous acid slurry (retained slurry) staying in the reaction unit 11b to a preferable range.

The absorption unit 11a has an introduction port 16 for a raw material gas containing sulfur dioxide and an outlet 18 for discharging an exhaust gas having a concentration of sulfur dioxide lower than that of the raw material gas. In the absorption unit 11a, the alkaline slurry supplied from the alkaline slurry tank 30 and the raw material gas introduced from the introduction port 16 are brought into contact with each other to absorb sulfur dioxide in the alkaline slurry. A gas discharge line 17 is connected to the outlet 18, and exhaust gas having a reduced sulfur dioxide concentration is discharged.

The slurry that has absorbed sulfur dioxide in the absorption unit 11a flows down to the reaction unit 11b below the absorption unit 11a. In the reaction section 11b, the alkaline compound contained in the alkaline slurry reacts with sulfur dioxide to generate a reducing agent slurry containing a sulfite. The generated reducing agent slurry stays in the reaction unit 11b. In the present disclosure, the reducing agent slurry retained in the reaction unit 11b may be referred to as "retained slurry", and the reducing agent slurry circulated in the circulation line 12 may be referred to as "circulating slurry".

The cooling unit 50 is connected to a heat exchanger 52 that exchanges heat with the stagnant slurry 22 staying in the reaction unit 11b. The cooling unit 50 supplies the refrigerant to the heat exchanger 52. The retained slurry 22 staying in the reaction unit 11b is adjusted to a temperature of, for example, 70 ° C. or lower by heat exchange with the refrigerant. The temperature of the retained slurry 22 in the reaction section 11b is preferably 60 ° C. or lower, more preferably 55 ° C. or lower, still more preferably 50 ° C. or lower, particularly preferably 45 ° C. or lower, most preferably 40 ° C. or lower, and even more preferably 35. Adjusted to below ° C. As a result, the temperature of the retained slurry can be reduced even when the external temperature is high (such as in summer) or when the temperature at which the raw material gas is introduced into the absorbing portion 11a is high. Therefore, it is possible to prevent oxidation of the produced sulfite and produce a reducing agent with higher efficiency. The temperature of the retained slurry 22 in the reaction section 11b may be 5 ° C. or higher and may be 10 ° C. or higher from the viewpoint of preventing freezing.

The manufacturing apparatus 100 may include a control unit that controls the temperature of the stagnant slurry 22. The control unit is based on the temperature information from the temperature measuring unit that measures the temperature of any of the stagnant slurry 22, the circulating slurry flowing through the circulation line 12, and the reducing material slurry derived from the lead-out line 15, and the stagnant slurry 22 You may control the temperature of. The control unit can control the temperature of the stagnant slurry 22 by, for example, adjusting the amount of refrigerant supplied from the cooling unit 50 to the heat exchanger 52 and / or the temperature of the refrigerant.

The concentration of the solid content of the retained slurry 22 in the reaction unit 11b may be 2 to 25% by mass. The concentration may be 10 to 23% by mass from the viewpoint of increasing the productivity of the reducing agent while improving the handleability. Further, the content of sulfite in the solid content is, for example, 40% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and particularly, from the viewpoint of improving the reactivity of the reducing agent. It is preferably 80% by mass or more, and most preferably 90% by mass or more. The content of each sulfite in the solid content can be determined by thermogravimetric analysis as shown in Examples or the XRD Rietveld method. The content of each bisulfite can be determined by the XRD Rietveld method.

The retention slurry 22 in the reaction unit 11b may be retained without blowing a gas containing oxygen (for example, air). This makes it possible to suppress the oxidation of sulfites. Therefore, the manufacturing apparatus 100 does not have to have the air supply mechanism attached to the ordinary flue gas desulfurization apparatus. However, it does not exclude those equipped with such oxidation equipment. When the reaction unit 11b has a mechanism for blowing a gas containing oxygen, the flow rate C [L / h] of the gas containing oxygen (for example, air) blown into the retained reducing material slurry 22 is introduced from the introduction port 16. It is preferably 10% by volume or less, more preferably 5% by volume or less, and further preferably 3% by volume or less based on the flow rate B [L / h] of the raw material gas. The flow rates B and C are flow rates when converted to the standard state.

The oxygen concentration contained in the raw material gas introduced from the introduction port 16 to the absorption unit 11a is, for example, 20% by volume or less, preferably 18% by volume or less, more preferably 15% by volume or less, and most preferably. It is 10% by volume or less.

A part of the retained slurry 22 staying in the reaction unit 11b is led out from the bottom of the slurry preparation tower 11 and circulated to the absorption unit 11a via the circulation line 12. The circulating slurry that has flowed through the circulation line 12 is sprayed into the absorption portion 11a from the nozzle 14 attached to the tip end portion of the circulation line 12. The circulating slurry descending in the absorption unit 11a and the raw material gas introduced into the absorption unit 11a from the introduction port 16 provided below the nozzle 14 come into countercurrent contact. As a result, sulfur dioxide contained in the raw material gas is sufficiently incorporated into the circulating slurry, and the production of sulfites is promoted.

The reducing agent slurry generated in the slurry preparation tower 11 is led out from the reaction unit 11b of the slurry preparation tower 11 by a lead-out line 15 and stored in the reducing agent slurry tank 20. The temperature range of the derived reducing agent slurry, the concentration range of the solid content, and the range of the sulfite content in the solid content may be the same as those of the retained slurry 22. The temperature range of the circulating slurry, the concentration range of the solid content, and the range of the content of sulfite in the solid content may be the same as those of the retained slurry 22.

The sulfite contained in the reducing material slurry may contain at least one sulfite of an alkaline earth metal and an alkali metal. Since such sulfites are sufficiently reactive, for example, when used as a soil conditioner, they sufficiently suppress the elution of hexavalent chromium from the solidified soil and increase the strength of the solidified soil. be able to. From this point of view, the sulfite preferably contains calcium sulfite. The reducing agent slurry may contain at least one of an alkaline earth metal and an alkali metal, hydrogen sulfite, together with the sulfite. By containing hydrogen sulfite, the elution of hexavalent chromium can be further suppressed.

The upper limit of the pH of the reducing agent slurry is, for example, 6.5 or less, preferably 6.3 or less, more preferably 6.0 or less, and further preferably 5.8 or less. The lower limit of the pH of the reducing agent slurry is 5.0 or more, preferably 5.3 or more, more preferably 5.4 or more, and further preferably 5.5 or more.

The content of sulfurous acid in the reducing agent slurry generated in the slurry preparation tower 11 is the temperature of the retained slurry 22 in the reaction unit 11b and / or the SO ₂ concentration contained in the raw material gas introduced from the introduction port 16 into the absorption unit 11a. Can be adjusted with. Specifically, the content of sulfurous acid in the reducing agent slurry can be increased by lowering the temperature of the retained slurry 22 and / or _{increasing the concentration of SO 2 introduced into the absorption unit 11a.}

The reducing material slurry led out to the reducing material slurry tank 20 may be concentrated in the moisture adjusting unit 40 to be a concentrated slurry, dehydrated to be a dehydrated cake, or further dried to be powdered. .. As described above, the manufacturing apparatus 100 can manufacture various forms of reducing agent including slurry, powder, and dehydrated cake.

As described above, the reducing agent produced by the reducing agent manufacturing apparatus of the present disclosure may be in the form of a slurry, a dehydrated cake, or a powder. Therefore, unless otherwise specified, the term "reducing agent" in the present disclosure is not limited to any form thereof, and includes, for example, any form of slurry, dehydrated cake, and powder. Further, the "reducing agent slurry" in the present disclosure is a slurry-like reducing agent and contains sulfite as a solid content. For example, the “retained slurry” retained in the reaction unit 11b and the “circulated slurry” circulated in the circulation line 12 are also a type of reducing agent slurry.

The obtained reducing agent may be mixed with cement clinker or Portland cement and gypsum to form a cement composition. However, its use is not limited to the cement composition, and may be used, for example, as a soil conditioner or a dechlorinating agent.

FIG. 2 is a diagram showing a reducing agent manufacturing apparatus according to another embodiment. In the reducing material manufacturing apparatus 200, the manufacturing apparatus 101 is connected to the downstream side of the manufacturing apparatus 100 of FIG. That is, the gas discharge line 17 of the first-stage manufacturing apparatus 100 is connected to the introduction port 16 of the second-stage manufacturing apparatus 101. In the second-stage manufacturing apparatus 101, the reducing agent is produced using the exhaust gas of the first-stage manufacturing apparatus 100 as a raw material gas.

_{The SO 2} concentration of the exhaust gas derived from the outlet 18 of the first-stage manufacturing apparatus 100 is preferably 0.1 to 3000 ppm, more preferably 1 to 1000 ppm, and further preferably 10 to 500 ppm. As described above, when the exhaust gas discharged from the gas discharge line 17 of the first-stage manufacturing apparatus 100 contains sulfur dioxide, the reducing agent can be produced in the second-stage manufacturing apparatus 101. It includes an exhaust gas SO ₂ discharged from the manufacturing apparatus 100, since it can be recovered SO ₂ contained in the exhaust gas in the manufacturing apparatus 101 as sulfite, increasing the SO ₂ concentration in the feed gas used in the manufacturing apparatus 100 Can be done. As a result, the content of sulfites in the reducing agent produced by the production apparatus 100 can be further increased. The apparatus configuration and operating conditions of the manufacturing apparatus 101 may be the same as those of the manufacturing apparatus 100 except that the exhaust gas of the manufacturing apparatus 100 is used as the raw material gas.

In the modification of the manufacturing apparatus 200, at least one of the alkaline slurry tank 30, the reducing agent slurry tank 20, the moisture adjusting section 40, and the cooling section 50 may be shared. Further, in another modification, one or a plurality of manufacturing devices similar to the manufacturing device 101 may be provided on the downstream side of the manufacturing device 101.

Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment. For example, in the manufacturing apparatus 100 of FIG. 1 and the manufacturing apparatus 200 of FIG. 2, a part of the circulation line 12 and the lead-out line 15 is shared, but the circulation line 12 and the lead-out line 15 are not limited to this. It may be individually connected to the reaction section 11b of the slurry preparation column 11. Further, in the above embodiment, the absorption unit 11a and the reaction unit 11b physically constitute one tower (slurry preparation tower 11), but the present invention is not limited to this, and for example, the absorption unit 11a and the reaction unit 11b. May be physically provided individually. For example, the absorption unit 11a and the reaction unit 11b may be composed of an absorption tower and a reaction tank, respectively. Further, in the above embodiment, the temperature of the stagnant slurry 22 is adjusted via the heat exchanger 52 installed in the reaction section 11b, but the temperature is not limited to this, and for example, the stagnant slurry 22 is the reaction section 11b. The temperature may be controlled by circulating the heat exchanger installed outside the.

The contents of the present disclosure will be described in more detail with reference to Examples and Reference Examples, but the present disclosure is not limited to the following examples.

( Reference Examples 1, 2, 6 and Examples 3 to 5, 7 )
[Preparation of reducing agent slurry]
In the manufacturing apparatus as shown in FIG. 1, a raw material gas at 200 ° C. containing sulfur dioxide was introduced from the raw material gas inlet. As shown in Table 1, the reducing agent slurries of Reference Examples 1, 2 and 6 and Examples 3 to 5 and 7 having different contents of calcium sulfite / hemihydrate were _{prepared by changing the SO 2 concentration in the raw material gas.} Manufactured. In both Reference Examples and Examples, the temperature of the retained slurry in the reaction section was 31 to 40 ° C.

[Analysis of solid content concentration in reducing agent slurry]
The reducing agent slurry was dried in air at 100 ° C., and the solid content concentration was measured from the amount of mass loss. The specific calculation formula is as follows. The solid content concentrations of each reference example and each example were as shown in Table 1.
-Solid content concentration (mass%) = (mass of reducing material slurry-mass reduction amount) / mass of reducing material slurry x 100

[Solid composition analysis]
The reducing agent slurry was filtered and dehydrated to obtain a cake. This cake was dried in air at 60 ° C. to obtain a solid content. The powder XRD analysis of the obtained solid content was performed, and it was confirmed that only calcium sulfite / hemihydrate, calcium carbonate, and dihydrate gypsum were detected. Then, thermogravimetric analysis was performed to determine the content (% by mass) of calcium sulfite hemihydrate, calcium carbonate, and dihydrate gypsum in the solid content. The results are as shown in Table 1. The analysis conditions are as follows.

<Powder XRD analysis>
An X-ray diffractometer (manufactured by Bruker AXS Co., Ltd., acceleration voltage: 30 kV, current: 10 mA, tube: Cu) was used.

<Thermogravimetric analysis>
Using a commercially available thermogravimetric analyzer, the change in thermogravimetric analysis when heated to 200 ° C., 600 ° C. and 900 ° C. was measured. At 200 ° C, the dihydrate gypsum dehydrates. Calcium sulfite oxidizes at 600 ° C. Calcium carbonate decomposes at 900 ° C. Using the change in mass at each temperature, the contents of dihydrate gypsum, calcium sulfite and calcium carbonate were calculated based on the following formulas. The sample mass is the mass of the solid content used in the thermogravimetric analysis. It should be noted that the holding at each heating temperature was set until the weight change disappeared. The holding time at each heating temperature was 1 hour. In addition, the atmosphere at the time of heating was air.

-Content rate of dihydrate gypsum (mass%) = mass reduction amount until the mass change disappears after heating from room temperature to 200 ° C. x ([Molecular weight of dihydrate gypsum] / [Crystal water contained in dihydrate gypsum] Molecular weight]) / sample mass x 100
-Calcium carbonate content (mass%) = (mass of sample after heating to 900 ° C and no change in mass) x [mass of sample after heating to -600 ° C and no change in mass) x [CaCO ₃ Molecular weight] / [Molecular weight of CO ₂ ] / Mass of sample x 100
-Calcium sulfite content (mass%) = 100- (dihydrate gypsum content + calcium carbonate content)

As shown in Table 1, Reference Examples 1, 2 and 6 and Examples 3 to 5 and 7 all contain calcium sulfite / hemihydrate, calcium carbonate and dihydrate gypsum in the solid content. , The content of calcium sulfite / hemihydrate was 30% by mass or more.

In Reference Examples 1 and 2 and Example 3 , it was confirmed that the content of calcium sulfite / hemihydrate tends to increase as _{the SO 2} concentration in the raw material gas increases. _{Further, when the SO 2} concentration is 1400 ppm or more as in Examples 3 to 5, the content of calcium sulfite / hemihydrate is increased to some extent even if the temperature of the reducing agent slurry (retained slurry) in the reaction section is high. It was confirmed that it could be done.

On the other hand, when comparing Reference Example 6 (SO ₂ concentration: 1190 ppm) _{having an SO 2} concentration of around 1000 ppm and Reference Example 2 (SO ₂ concentration: 953 ppm), Reference Example 6 having a slurry temperature of 40 ° C. However, the content of calcium sulfite / hemihydrate was lower than that of Reference Example 2 in which the slurry temperature was 31 ° C. From this, it was confirmed that the content of calcium sulfite / hemihydrate can be increased by lowering the temperature of the retained slurry. Further, _{it was confirmed that even when the SO 2} concentration of the raw material gas is low as in Reference Example 1 and Reference Example 2, the content of calcium sulfite / hemihydrate can be sufficiently increased by lowering the temperature of the retained slurry. rice field.

According to the present disclosure, according to the present disclosure, it is possible to provide an apparatus for producing a reducing agent capable of inexpensively and stably producing a reducing agent containing a sulfite.

11 ... Slurry preparation tower, 11a ... Absorption part, 11b ... Reaction part, 12 ... Circulation line, 14 ... Nozzle, 15 ... Derivation line, 16 ... Introduction port, 17 ... Gas discharge line, 18 ... Derivation port, 20 ... Reducing material Slurry tank, 22 ... Retained slurry, 30 ... Alkaline slurry tank, 40 ... Moisture adjusting unit, 50 ... Cooling unit, 52 ... Heat exchanger, 100, 101 ... Manufacturing equipment, 200 ... Manufacturing equipment.

Claims (8)

Look containing sulfur dioxide, SO ₂ concentration and an electrical outlet in which the concentration of sulfur dioxide than inlet port and the raw material gas of the material gas is more than 1450ppm for discharging a low exhaust gas, carbonate and water calcium Calcium an alkali slurry containing alkaline compounds and water contains at least one selected from the group consisting of oxides, and the absorbing portion for absorbing the sulfur dioxide in the source gas and brought into contact with and alkaline slurry,
A reaction unit that reacts the alkaline compound with the sulfur dioxide to produce a reducing agent slurry containing calcium sulfite.
A circulation line that circulates the reducing agent slurry staying in the reaction section to the absorption section,
A nozzle for spraying the reducing agent slurry is circulated by the circulation line to the absorbing portion,
An apparatus for producing a reducing agent, comprising a cooling unit for cooling the reducing agent slurry staying in the reaction unit. The temperature of the raw material gas introduced into the absorption unit is controlled to 50 to 400 ° C.
The reducing agent manufacturing apparatus according to claim 1, wherein the temperature of the reducing agent slurry staying in the reaction unit is controlled to 70 ° C. or lower. And alkaline slurry tank mixing with water the alkali compound to produce the alkali slurry,
A derivation line for deriving the reducing agent slurry that stays in the reaction unit, and
The reducing agent manufacturing apparatus according to claim 1 or 2, further comprising a reducing agent slurry tank for storing the reducing agent slurry derived from the reaction unit. The apparatus for producing a reducing agent according to any one of claims 1 to 3, wherein the temperature of the reducing agent slurry staying in the reaction unit is adjusted to 35 ° C. or lower. The reducing agent slurry containing sulfite calcium hydrogen reducing material production apparatus according to any one of claims 1-4. Is blown into the reducing agent slurry staying in the reaction part, the flow rate of the gas containing oxygen is 10 vol% or less of the flow rate of the raw material gas introduced from the introduction port as a reference, according to claim 1 to 5 The reducing agent manufacturing apparatus according to any one of the following items. The reducing agent manufacturing apparatus according to any one of claims 1 to 4, wherein the reaction unit retains the reducing agent slurry without blowing a gas containing oxygen into the reducing agent slurry. _{The SO 2} concentration of the exhaust gas at the outlet is 0.1 to 3000 ppm.
The reducing agent manufacturing apparatus according to any one of claims 1 to 7, further comprising an absorbing portion for bringing the exhaust gas into contact with the alkaline slurry.

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