KR19990052236A - Desulfurization Sorbent with Improved Desulfurization Performance Using Hydrogen Peroxide - Google Patents

Abstract

The present invention relates to a desulfurization absorbent having improved desulfurization performance using hydrogen peroxide water.

In preparing a wet flue gas desulfurization absorbent,

Provided is a desulfurization absorbent having improved desulfurization performance by mixing hydrogen peroxide water at a concentration of 1,000 to 20,000 ppm in a limestone slurry containing 40% CaO.

According to the present invention, it was possible to obtain only CaSO ₄ 1 / 2H ₂ O without supplying air while using the existing sulfur desulfurization process apparatus as it is, and also improved the SO ₂ removal performance.

Description

Desulfurization Sorbent with Improved Desulfurization Performance Using Hydrogen Peroxide

The present invention relates to a desulfurization absorbent having an improved desulfurization performance using hydrogen peroxide, and more particularly, to improve the desulfurization performance of the desulfurization absorbent by using hydrogen peroxide and furthermore, CaSO ₃ ㆍ 1, which is a water pollutant produced by the desulfurization reaction. A desulfurization absorbent which inhibits the production of / 2H ₂ O.

There has long been a systematic study of commercializing flue gas desulfurization processes to reduce emissions of sulfur dioxide (Toprac, AJ and Rochelle, GT, Environmental Progress , 1 , 52-58 (1982); Wasag, T., Galka , J. and Fraczak, M., Hrona Powietrza , 9 , 16-24 (1975); Goodwin, RW, J. of the Air Pollution Control Association , 28 , 35-39 (1978)).

There are dozens of flue gas desulfurization processes developed to date, each of which has characteristics and advantages and disadvantages, but non-regenerated wet limestone-gypsum is the most widely commercialized (Rinardi, INU, Environmental Engineering World , 59 , 18). -24 (1995)).

The wet limestone-gypsum method is a method of fixing and recovering the absorbent limestone as gypsum by using a limestone slurry as a SO ₂ absorbent, and inducing a forced oxidation reaction of CaSO ₃ ㆍ 1 / 2H ₂ O generated during SO ₂ absorption. For this purpose, a separate oxidizing tank is placed or air is introduced into the reactor so that CaSO ₃ ㆍ 1 / 2H ₂ O oxidation reaction occurs simultaneously with SO ₂ absorption.

The SO ₂ absorption reaction by the general flue gas desulfurization absorber proceeds by the following reaction formula.

SO ₂ + H ₂ O → H ₂ SO ₃ → 2H ⁺ + SO ₃ ^2-

CaCO ₃ + 2H ⁺ → Ca ²⁺ + H ₂ O + CO ₂

Ca ²⁺ + SO ₃ ^2- + 1 / 2H ₂ O → CaSO ₃ ㆍ 1 / 2H ₂ O

_{^{Ca 2+ + 2SO 3 2- → Ca}} (SO 3) 2

CaSO ₃ ㆍ 1 / 2H ₂ O + 1 / 2O ₂ + 3 / 2H ₂ O → CaSO ₄ 2H ₂ O

However, these methods use low-solubility air in water to completely oxidize CaSO ₃ ㆍ 1 / 2H ₂ O to CaSO ₄ ㆍ 2H ₂ O, so the size of the oxidizing tank to be installed separately becomes very large or injected into the reactor. A large capacity air compressor is required because the amount of air that is needed must be maintained at about 15% of the exhaust gas flow rate.

Accordingly, an object of the present invention is to add a hydrogen peroxide solution to induce a forced oxidation reaction of CaSO ₃ ㆍ 1 / 2H ₂ O generated in the SO ₂ absorption process without the need for excessive air injection or a separate oxidizing tank at the same time SO _{It is an object} of the present invention to provide a desulfurization absorbent having improved absorption capability of ₂ .

1 is a graph showing the results of XRD (X-ray diffraction) analysis in the case of the conventional method with no air and 6,000 ppm hydrogen peroxide solution according to the present invention,

FIG. 2 is a graph showing the results of FR-IR analysis when 3,000 ppm of hydrogen peroxide solution and no hydrogen peroxide solution were added by the method of the present invention.

FIG. 3 is a graph showing SO ₂ emission concentration and pH change of slurry with time according to the conventional method without introducing air and when 6,000 ppm of hydrogen peroxide solution is added according to the present invention.

According to the invention,

In preparing a wet flue gas desulfurization absorbent,

Provided is a desulfurization absorbent having improved desulfurization performance by mixing hydrogen peroxide water at a concentration of 1,000 to 20,000 ppm in a limestone slurry containing 40% CaO.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

In the present invention, hydrogen peroxide solution is added to the conventional desulfurization absorber to suppress the generation of CaSO ₃ .1 / 2H ₂ O, which is a water pollutant, by the following reaction formula.

SO ₂ + H ₂ O ₂ → H ₂ SO ₄ → 2H ⁺ + SO ₄ ^2-

CaCO ₃ + 2H ⁺ → Ca ²⁺ + H ₂ O + CO ₂

Ca ²⁺ + SO ₄ ^2- → CaSO ₄ ㆍ 1 / 2H ₂ O

Looking at the above formulas in more detail, since the absorption reaction of SO ₂ directly converted to H ₂ SO ₄ to suppress the production of CaSO ₃ .1 / 2H ₂ O in the solution. In addition, since the generated calcium ions and SO ₄ ^2- ions react directly, the production of CaSO ₃ .1 / 2H ₂ O is suppressed.

For such a reaction, hydrogen peroxide water is added to CaO at a concentration of 40%, and the amount of hydrogen peroxide is preferably added at a concentration of 1,000-20,000 ppm in the CaO sludge.

When the hydrogen peroxide number is less than 1,000ppm, insufficient oxidation prevents the production of CaSO ₃ ㆍ 1 / 2H ₂ O, and the concentration of hydrogen peroxide maintained in the sludge is limited, so the effect of the present invention is added even if it is added more than 20,000 ppm. Does not improve anymore.

In addition, after the hydrogen peroxide solution is added at a concentration of 1,000-20,000 ppm, it is preferable that the pH of the entire reaction solution is maintained at 3.0-5,0. Hydrogen peroxide reacts suitably within the said pH range.

Further, according to this reaction, only CaSO ₄ 1 / 2H ₂ O can be obtained in a nitrogen atmosphere without introducing any air, and the SO ₂ gas removal capability is improved.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described.

<Example>

Desulfurization tests were performed using laboratory scale desulfurization equipment.

In order to adjust the concentration of the introduced gas to 1600 ppm, the flow rate of the simulated gas having a SO ₂ of 1.5% concentration under a nitrogen atmosphere was introduced into the reactor using a mass flow controller.

The size of the reactor was 25cm in height and 15cm in diameter, and transparent acrylic was used as a reactor material for internal observation. Oxidation air was not separately injected into the reactor, and the pressure difference between the reactor inlet and outlet was maintained at 100 mmAq.

A magnetic stir bar and a magnetic hot plate were used to prevent the precipitation of the slurry. The products produced in the reactor were collected at 30-minute intervals, and the X-Ray Diffraction (XRD), FR-IR (Fourier Transform infrared spectrometer and SEM (scanning electron microscope) photograph were analyzed.

In addition, a pH meter was installed in the reactor to measure the pH change according to the reaction time, and the SO ₂ concentration removal efficiency over time was recorded using a SO ₂ concentration meter (see FIG. 3).

Comparative Example 1

Desulfurization reaction was carried out without supplying air to the reaction conditions described in the reaction apparatus using only pure limestone as the absorbent.

The number of moles of SO ₂ removed per unit mass of limestone absorbent was 8.7 × 10 ⁻⁵ mol / g, and the resulting reactant was a mixture of CaSO ₃ .1 / 2H ₂ O and Ca (SO ₃ ) ₂ . The X-ray diffraction (XRD) analysis results are shown in FIG. 1.

Comparative Example 2

The desulfurization reaction was carried out under the same reaction conditions as in Comparative Example 1 except that a reaction apparatus equipped with an air compressor was used in the above-described apparatus and air for forced oxidation was supplied.

The number of moles of SO ₂ removed per unit mass of limestone absorbent was 6.0 × 10 ⁻⁵ mol / g, and the resulting reactant was CaSO ₄ .1 / 2H ₂ O.

According to the method, CaSO ₃ .1 / 2H ₂ O, which is a water pollutant, was not produced at all, but the SO ₂ removal performance was inferior to that of Comparative Example 1.

Example 1

Desulfurization reaction was carried out without supplying air in the reaction apparatus described in Comparative Example 1 using pure limestone and 3,000 ppm hydrogen peroxide as the absorbent.

The number of moles of SO ₂ removed per unit mass of limestone absorbent was 9.0 × 10 ⁻⁵ mol / g, and the resulting reactant was CaSO ₄ .1 / 2H ₂ O. The FR-IR analysis result is shown in FIG.

Example 2

Desulfurization reaction was carried out without supplying air in the reaction apparatus described in Comparative Example 1 using pure limestone and 6,000 ppm hydrogen peroxide as the absorbent.

The number of moles of SO ₂ removed per unit mass of limestone absorbent was 15.0 × 10 ⁻⁵ mol / g, and the resulting reactant was CaSO ₄ .1 / 2H ₂ O. The XRD (X-ray diffraction) analysis result is shown in FIG.

Referring to FIG. 1, it was confirmed that CaSO ₄ ㆍ 1 / 2H ₂ O was generated from the peak near 2θ = 10 of the present invention, and when only nitrogen was added without introducing air according to Comparative Example 1, doublet (2θ = 15) And 2θ = 30), a mixture of CaSO ₃ .1 / 2H ₂ O and Ca (SO ₃ ) ₂ can be estimated.

In addition, according to FIG. 2, a strong peak can be seen in the vicinity of the SO ₄ ^2- value literature value from the IR graph to which 3,000 ppm of hydrogen peroxide solution of the present invention is added. Furthermore, in FIG. 3, it can be seen that CaSO ₄ is removed by reacting with H ₂ O even at an SO ₂ emission concentration. In this case, it is most preferable to maintain the pH of the slurry between 3 and 5.

Taken together, in comparison with the comparative example without addition of hydrogen peroxide solution, in Examples 1 and 2 using the method of the present invention, production of CaSO ₃ 1 / 2H ₂ O was suppressed without supplying air, and at the same time, _{2 The amount of} removal also increased.

In addition, some of the air may be injected to maximize the SO ₂ removal effect of the present invention, and in this case, there is an advantage of reducing the capacity of the air compressor installed for air injection.

According to the above, it was possible to obtain only CaSO ₄ 1 / 2H ₂ O without supplying air while using the existing sulfur desulfurization process equipment as it is, it is possible to improve the SO ₂ removal performance.

Claims (2)

In preparing a wet flue gas desulfurization absorbent, Desulfurization absorber with improved desulfurization performance using hydrogen peroxide water mixed with hydrogen peroxide at a concentration of 1,000-20,000 ppm in limestone slurry containing 40% CaO The desulphurized absorbent of claim 1 wherein the pH of the absorbent is maintained at 3.0-5.0.