JPH0513526U - Device for detecting air oxidation inhibitors in aqueous solution - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to an air oxidation inhibitor detection device applied to an air oxidation facility of a limestone gypsum method desulfurization device. [Structure] An air supply means, a sulfurous acid-containing liquid supply means, an alkali supply means, and a retained liquid discharge means are connected by piping to a reactor equipped with an agitator for mixing a retained liquid with an air supply port at the bottom, The pH of the retained liquid in the reactor is detected, the alkali supply means is operated by the detection signal, the retained liquid level in the reactor is detected, and the retained liquid discharge means is operated by the detection signal, and the discharge liquid piping A device for detecting air oxidation inhibitors in aqueous solution, which is connected to a sulfurous acid detector.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for detecting an air oxidation inhibitor applied to an air oxidation equipment of a limestone gypsum method desulfurization device.

[0002]

[Prior Art]

 Limestone (CaCO₃The slurry prepared by suspending the powder of 1) in water is used as an absorbent. Sulfur dioxide gas (SO₂) Is an aqueous phase and is subjected to bisulfite ion (HSO) by the reaction of the following formulas (1) and (2).₃ ^- ) Is generated. SO₂(G) + H₂O → H₂SO₃ (1) H₂SO₃→ H⁺+ HSO₃ ^- (2)

[0003] Further generated HSO ₃ ^- in whole or in part reacts with O ₂ in the air supplied from the oxygen O ₂ and / or the outer portion of the flue gas following formula (3) by bisulfate ion (HS O ₄ ^-) to generate. ^{_{HSO 3 - + 1 / 2O 2}} (g) → HSO 4 - (3)

The produced HSO ₄ ⁻ reacts with limestone (CaCO ₃ ) in the slurry to produce a byproduct gypsum (CaSO ₄ .2H ₂ O) according to the following formula (4). ^{_{HSO 4 - + H + + CaCO}} 3 + H 2 O → CaSO 4 · 2H 2 O + CO 2 (4)

The reaction of the above (3) is affected by the O ₂ concentration in the exhaust gas and the air supply amount, but is also greatly affected by the inclusion of the oxidation inhibiting substance. That is, when the air supply amount is insufficient or when the oxidation inhibitor is mixed and the oxidation is suppressed, the HSO ₃ ⁻ concentration in the slurry increases and the normal HSO ₃ ⁻ concentration becomes 10 to 20 mmol / l or more. Lime sulfite (CaSO ₃ ) is produced by the reaction represented by the equation (5). ^{_{HSO 3 - + H + + CaCO}} 3 → CaSO 3 · 1 / 2H 2 O + 1 / 2H 2 O + CO 2 (5)

CaSO₃Since the formation of slag is a factor that deteriorates the quality of by-product gypsum, it is usually HSO.₃ ^- The air supply rate is adjusted so that the concentration becomes 1 mmol / l or less.

However, when the oxidation inhibitor is mixed and the oxidation is suppressed, the oxidizing ability of the oxidizer cannot be fully exerted, CaSO ₃ is produced, and the quality of the by-product gypsum is deteriorated.

Therefore, it is necessary to previously evaluate the presence or absence of an oxidation inhibiting substance caused by impurities contained in limestone, makeup water, exhaust gas and the like.

[0009]

[Problems to be solved by the device]

 In the conventional evaluation of the presence or absence of oxidation inhibitors, the solution to be measured is usually placed in a stirring tank, etc., and water-soluble sulfite such as sodium sulfite is added at once to perform batch oxidation, and the oxidation rate is determined from the decrease curve of sulfite concentration. The method of seeking is done. However, this method can only obtain the oxidation rate in the region where the sulfite concentration is relatively high, and it was difficult to accurately measure the oxidation rate at a low concentration of sulfite concentration of 5 mmol / l or less applied by the limestone gypsum method. .

In view of the above-mentioned state of the art, the present invention is a device that can simulate the operating conditions of an actual air oxidation equipment of a limestone gypsum method desulfurization device and can accurately determine the presence or absence of an air oxidation inhibitor in an aqueous solution at low cost. Is to provide.

[0011]

[Means for Solving the Problems]

 According to the present invention, an air supply means, a sulfurous acid-containing liquid supply means, an alkali supply means and a retained liquid discharge means are connected by piping to a reactor equipped with an agitator for mixing an accumulated liquid with an air supply port at the bottom. The pH of the retained liquid in the reactor is detected, the alkaline supply means is operated by the detection signal, and the retained liquid level in the reactor is detected, and the retained liquid discharge means is operated and discharged by the detection signal. A device for detecting an air oxidation inhibitor in an aqueous solution, characterized in that a sulfur dioxide detector is connected to the liquid pipe.

[0012]

[Action]

 Put a certain amount of the solution to be measured in the reactor, stir with a stirrer, operate the air supply pump to supply a certain amount of air, and supply the sulfurous acid solution at a constant rate through the sulfite supply pump. Supply in. The pH of the liquid in the reactor is detected by the pH sensor and measured by the pH meter, and the pH value is input to the pH controller. The pH adjuster sends a signal to the alkali supply pump to operate the alkali supply pump to send the alkali solution into the reactor, and the alkali supply pump is operated so that the pH of the solution in the reactor maintains the set pH value. Control.

Most of the sulfurous acid solution supplied to the reactor is air-oxidized to form bisulfate ions according to the above formula (3), and further neutralized by the alkaline liquid supplied along with the pH adjustment. , The liquid is automatically discharged by the liquid level controller to reach the specified level. The sulfite concentration in the liquid in the reactor is measured by a sulfite concentration analyzer.

As described above, in the present invention, since the sulfurous acid solution is continuously supplied and the pH is adjusted, continuous air oxidation is performed in conformity with an actual desulfurization device, so that the oxidation inhibition of the measured liquid is quantitative and accurate. Can measure well.

[0015]

【Example】

 An embodiment of the detection device of the present invention will be described with reference to FIG. In the apparatus of this embodiment shown in FIG. 1, after a certain amount of water to be measured is put into a reactor 1 having a constant temperature water jacket 16 in the outer peripheral portion, stirring is started by a stirrer 2. After reaching a predetermined temperature, a predetermined flow rate of air is supplied from an air supply pump 3 through a pipe through an air blowing pipe 4 provided in the lower portion of the reactor 1. The sulfurous acid solution is sent from the sulfurous acid solution container 5 through the sulfurous acid solution supply pump 6 into the reactor 1 at a constant rate to start the air oxidation of sulfurous acid.

The pH of the liquid in the reactor 1 is detected by the pH sensor 7 and measured by the pH meter 8, and the pH value is input to the pH controller 9. The pH controller 9 signal is sent to the alkaline liquid supply pump 10 according to the deviation between the measured pH value and the set pH value so that the liquid pH value in the reactor 1 becomes the set pH value. Then, the alkaline solution is sent from the alkaline solution container 11 to the reactor 1, and the pH value of the solution in the reactor 1 to which the alkaline solution is supplied is maintained at a predetermined value.

The liquid level inside the reactor 1 is detected by the liquid level sensor 12, and the liquid level adjusting meter 13 turns on / off the liquid draining pump 14 so that the liquid level is adjusted to a set level. Withdraw the liquid so that the liquid level setting value is reached.

A part of the liquid in the reactor 1 is sent to the sulfite concentration analyzer 15 through a pipe, and the sulfite concentration in the liquid is measured.

The oxidation inhibitor contained in the limestone gypsum absorption liquid is mixed from the absorbent raw material used, raw water and exhaust gas, and it is generally very difficult to identify the oxidation inhibitor in a trace amount at present. .

When the presence or absence of inhibition of air oxidation is measured using the apparatus of the above-mentioned embodiment, the criteria are as follows: temperature, pH, amount of oxidizing air, stirring rotation speed, and sulfur dioxide supply rate are the same. Relative comparison based on pure water containing no oxidation inhibitors, for example, the concentration of sulfite in pure water is 0.2 mmol / l or less, and 10 ppm of hydroquinone, which is known as a sulfite oxidation inhibitor, is added. The concentration of sulfurous acid is about 10 mmol / l in the prepared liquid.

It should be noted that sulfite water, sodium bisulfite and the like are suitable for the sulfurous acid solution, and caustic soda, calcium carbonate and the like can be used for the alkaline liquid.

[0022]

Effect of the Invention In the present invention, the sulfite solution is continuously supplied at a constant flow rate, the pH in the reactor is controlled at a constant level, the liquid level is also maintained at a constant level, and stable continuity is achieved. The presence or absence of oxidative inhibition can be accurately measured, and it can be utilized to judge the presence or absence of oxidative inhibitors.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a device for detecting an air oxidation inhibitor in an aqueous solution of the present invention.

[Explanation of symbols]

 1: Reactor 2: Stirrer 3: Air supply pump 4: Air supply pipe 5: Sulfurous acid solution container 6: Sulfurous acid solution supply pump 7: pH sensor 8: pH meter 9: pH controller 10: Alkaline solution supply pump 11: Alkaline liquid container 12: Liquid level sensor 13: Liquid level controller 14: Liquid removal pump 15: Sulfurous acid concentration analyzer 16: Constant temperature water jacket

Claims (1)

[Scope of utility model registration request] 1. An air supply means, a sulfurous acid-containing liquid supply means, an alkali supply means, and a staying liquid discharge means are connected by piping to a reactor having an agitator for mixing a staying liquid having an air supply port at the bottom. Detecting the pH of the retained liquid in the reactor, operating the alkali supply means with the detection signal, further detecting the retained liquid level in the reactor, and operating the retained liquid discharge means with the detection signal and discharging A device for detecting an air oxidation inhibitor in an aqueous solution, comprising a sulfurous acid detector connected to a liquid pipe.