WO2005028083A1

WO2005028083A1 - Novel desulfurizing agent for dry desulfurization process

Info

Publication number: WO2005028083A1
Application number: PCT/JP2004/009596
Authority: WO
Inventors: Masayoshi Sadakata; Masateru Nishioka; Norihiko Matsushima; Daichi Nakajima
Original assignee: Japan Science And Technology Agency
Priority date: 2003-09-18
Filing date: 2004-06-30
Publication date: 2005-03-31
Also published as: JP2005087893A

Abstract

A desulfurizing agent which comprises fine slaked lime particles containing 10 to 1000 ppm of a transition metal ion, in particular, Fe3+ as a desulfurizing component; and, preferably, a desulfurizing agent which comprises a carrier comprising fly ash and, carried on the surface thereof, the above fine slaked lime particles.

Description

Description New desulfurizing agent for dry desulfurization process

According to the present invention, desulfurized particles of slaked lime containing at least 1 ppm of transition metal ions, particularly trivalent iron ions, are used as the desulfurization component, or at least 10 ppm A desulfurizing agent having a structure to which a desulfurizing component composed of fine particles of slaked lime containing trivalent iron ions is attached, particularly a desulfurizing agent using fly ash as a carrier material . Background art

S 0 ₂ emissions in China is 1 8 1 4 million tons time 1 9 9 4 years, became the world's largest so ₂ emissions by far the § main Li mosquitoes at this time. With the rapid population growth seen in recent years and industrialization due to rapid economic growth, it is still on the rise. Air pollution from this SO ₂ emission has become a very serious problem. Emissions of SO ₂ is, regardless Osama only to the problem of the emitting countries, is SO ₂ which is discharged into the atmosphere pours into neighboring countries become acid rain, it has given the damage.

Ni will Yo of the above, the neighboring countries of China, has discharged a large amount of so _2, the emissions equivalent to about 70% of SO ₂ emissions of the entire Asia. Therefore, controlling emissions from their sources is of great significance for the Asian region, and is an issue that must be resolved urgently. The main sources in China are industrial boilers and power plants. It is clear that installing desulfurization equipment in these facilities and performing desulfurization will lead to a significant reduction in SO ₂ emissions. On the other hand, the damage caused by SO ₂ emissions was widespread in Japan, but now the development of wet desulfurization methods that can achieve high desulfurization rates and the widespread use of equipment have led to the lowest levels of so ₂ emissions in developed countries. Has become. However, while the wet desulfurization method has a high desulfurization rate, the construction and operation costs are high.In particular, large quantities of gypsum must be used in order to eliminate scale adhesion to absorption pipes and pipe mist removers. Therefore, it is not suitable for dissemination in developing countries such as China and inland continents.

For this reason, as a desulfurization method suitable for developing countries, a dry desulfurization method that is low-cost, uses little water and does not require water has attracted attention, and is being developed.

Under these circumstances, the present inventors have found a practical dry desulfurization method, and have developed a new dry desulfurization agent useful for a new dry desulfurization method using fly ash and quicklime as raw materials. Have been working. By combining the obtained dry desulfurization agent with a desulfurization device that forms a circulating fluidized bed, efforts have been made to develop a dry desulfurization method and device that can be used even in environments with little water resources.

Yan Li and others are developing dry desulfurization agents that are cheap and easy to purify using fly ash and quicklime as raw materials. This dry desulfurizing agent is obtained by mixing CaO into a mixture of fly ash and water at room temperature, stirring to form slurry, and drying the obtained slurry. Manufactured. Desulfurizing agent obtained in this good resold as compared with the case of desulfurization with C a O, utilization C a is about 3 times, split the C a SO ₄ Is higher than C a O. This is due to the C a (OH) specific surface area and pore volume C a (OH) ₂ in the fly ash _{surface 2} of the particles constituting the wire carrier rear without agglomeration this adhering remains microparticles Fuetako It is considered something. Also, research on a desulfurization method in which the desulfurizing agent is combined with a fluidized-bed reactor has been advanced, and the desulfurization method may increase the desulfurization rate by 20 to 30% as compared with Ca (OH) _2. It has been confirmed.

Furthermore, Japanese Patent Application No. 2000-2 — 24612.5 (filed on August 27, 2004) states that the desulfurization method using a circulating fluidized bed combined with NO _x added gypsum recovery. It was possible to achieve a maximum desulfurization rate of 83% at a Ca / S molar ratio of 2.2, albeit on a laboratory scale. However, on the pilot plant scale, the desulfurization rate was 80% when the Ca_S molar ratio was 3.

In the Journal of the Fuel Association, Vol. 45, No. 57, ppl 69-174, pp175-183, 1979 (Reference 1), Ishihara et al. It has been reported that the desulfurization efficiency is increased by including OH.

However, conventional technologies have problems such as catalyst efficiency related to scale-up, desulfurization rate of desulfurizing agent itself, and improvement of cost.

Therefore, an object of the present invention is to improve the above problems, and in particular to improve the above problems by providing a desulfurizing agent having an improved desulfurization rate. In order to achieve the above object, a means for improving the desulfurization rate based on a dry desulfurizing agent using slaked lime fine particles which are easy to handle and studied as a desulfurizing component studied by the present inventors has been found. And thought it was good. Among them, the present inventors have proposed the desulfurizing agent As means for improving the conversion efficiency of SO _x to gypsum, it was conceived to find an additive component for improving the conversion efficiency. We considered that Fe could be used as the above-mentioned additive component, and conducted experiments to try physical mixing, coprecipitation method, impregnation method, etc. as the method of adding Fe to the dry desulfurization agent. . Focusing on impregnation therein, in the impregnation method, a solution containing iron are use in impregnation, F e S 0 ₄ _{_{solution, F e (NH 4) 2}} (SO 4) 2 aqueous solution, and F e ( NO 3) ₃ solution, this Fe salt solution was added to a fly ash solution obtained by pouring fly ash into water, and CaO was gradually added to the resulting solution. Pulverization was performed to prepare a dry desulfurizing agent comprising fly ash having fine particles of Ca (OH) ₂ containing Fe on the surface. Then, the activity test desulfurization agent prepared above, as a sample gas, the initial concentration of the gas, S 0 ₂ to 1 5 5 0 ppm, O ₂ force S 7. 5%, and balance of N ₂ It measured using the gas which consists of. Consequently impregnation method by Ri F e ion, especially F e (NO _{₃₎ 3} solution dry desulfurizing agent to the desulfurization component fine particles of slaked lime blended with F e ^{3 +} ions with the desulfurized high efficiency desulfurization agent And found that the above object can be achieved. Disclosure of the invention

The first aspect of the present invention is (1) a desulfurizing agent comprising slaked lime fine particles containing at least 10 ppm of a transition metal ion as a desulfurizing component. Good Mashiku is (2) a desulfurizing agent according to the transition metal is iron (1), yo Ri preferred details, (3) according to the iron ion is F e ^{3 +} (2) And more preferably, (4) at least The slaked lime fine particles containing 10 ppm of transition metal ions are formed by a preparation method including a step of charging quick lime into an aqueous solution or solution of a transition metal, stirring, and then drying. 2) or the desulfurizing agent according to (3).

Further, the second aspect of the present invention is (5) a desulfurization wherein the slaked lime fine particles having a structure in which particles of slaked lime mixed with at least lO ppm of transition metal ions are adhered to a carrier surface are used as desulfurizing components. Agent. Preferably, (6) the transition metal is desulfurizing agent according to the iron (5), preferably, be a desulfurizing agent according to (7) wherein the iron ions are F e ^{3 +} (6) More preferably, (7) the slaked lime fine particles having a structure in which fine particles of slaked lime mixed with at least 遷移 Ο ρ ρm transition metal ions are attached to the surface of the carrier, the fine particles of slaked lime are an aqueous solution of transition metal. Or (5), (6) or (7), which is formed by a preparation method including a step of charging and agitating quicklime into a solution, a step of charging and stirring a carrier constituent, and a step of drying. )), And more preferably (9) the desulfurizing agent according to (5), (6), (7) or (8), wherein the carrier component is fly ash.

The Kiyariya component, JP 2 0 0 2 - 1 1 3 3 6 1 JP, in earthenware pots I are described in particular in the range及Pi embodiment according, to C a S 0 ₄ absorbs so ₂ It is a spherical particle having a function of coating and holding the formed Ca (OH) ₂ fine particles on the surface, and preferably has an average particle diameter of at least 5 times the particle diameter of the Ca (OH) ₂ fine particles. Brief Description of Drawings FIG. 1 shows an experimental apparatus for confirming the Ca conversion rate (corresponding to the desulfurization rate) of the dry desulfurizing agent provided by the present invention. The test gas used was composed of S 0 ₂ , O ₂ and N ₂ . The test gas is supplied to a desulfurization section DSA (desulfurizing agent + glass wool) of a reaction tube RC heated in a cylindrical furnace CH. The gas composition at the outlet of the reaction tube was measured using a gas analyzer GA. The temperature of the desulfurization section DSA controls the heating of the cylindrical furnace CH while observing the thermocouple TC. The glass wool layers placed before and after the desulfurization section are for stabilizing the desulfurization section. As the reaction tube R.C, for example, a Pyrex glass tube was used.

FIG. 2 shows the correlation between the Ca conversion rate (mo 1%) of Example 2 and the iron concentration of the Fe (NO 3) ₃ solution used for blending Fe ^{3 +} . From this figure, it can be seen that when the amount of iron added is 100 ppm, the Ca conversion rate is the highest. However, the gradient is expected to be more effective at higher levels. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail.

A. Fig. 1 shows an experimental device for confirming the Ca conversion rate (corresponding to the desulfurization rate) of the dry desulfurizing agent provided in the present invention. The SO ₂ in the test gas having containing, were used as the _{SO 2 1 5 5 0 ppm,} 0 2 7. 5%. The remainder was N _2. The test gas was introduced into a desulfurization section DSA (desulfurizing agent + glass wool) of a reaction tube RC heated to 350 ° C in a cylindrical furnace CH at 20 OmL / min. At a flow rate of The residence time of the test gas in the desulfurization section is 1 second. 'The gas composition at the outlet of the reaction tube is determined by the gas analyzer G.A., here, the portable gas analyzer. It was measured using HORIBAPG-250. The temperature of the desulfurization section DSA was controlled by controlling the heating of the cylindrical furnace CH while observing the thermocouple TC. A glass wool layer was placed before and after the desulfurization section for stabilization. For example, a pyrex glass tube having an inner diameter of 15 mm was used as the reaction tube R.C, and the length of the desulfurization section D.S.A was about 200 mm.

B. The transition metals to be incorporated to improve the desulfurization rate are preferably iron group, Fe, Ni, and Co, and particularly preferably trivalent Fe. . Example

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1

Pour pure water into a 5 O ml beaker. The pure water is stirred, and the amount of fly ash shown in Table 1 below is added thereto at a time. After stirring for a while, CaO is gradually added to the fly ash charging water in the amount shown in Table 1. In this way, a dispersion liquid in which C a (OH) ₂ was dispersed on fly ash was prepared. Then, 10 mL of a solution of an iron salt shown in Table 1 was added to the dispersion. After stirring for a while, the mixture was transferred to a petri dish, placed in an oven, dried at 85 ° C, allowed to cool, and then ground in a mortar. The activity test of the obtained desulfurizing agent was performed using the experimental device shown in Fig. 1. Table 1 shows the experimental conditions and Table 2 shows the activity test results.

C a conversion (m o 1%) =

[The total amount of _{C a SO 3 + C a S} 0 4 in the sample (mo 1)] / [sample Of the total C a (mo 1)].

The desulfurization section D.S.A was filled with 6-8 g of a desulfurization agent dispersed in glass wool. The test gas was allowed to flow at 200 mL for 60 minutes to perform a desulfurization reaction, and the conversion was determined.

【table 1 】

[Table 2]

From the above results, the Ca conversion correlated with the improvement of the desulfurization rate It is clear that the conversion rate is improving. In particular, it can be seen that the desulfurizing agent containing Fe ^{3 +} and using Fe 3 (NO 3) 3 is excellent.

Example 2

Based on the results of the use of the F e (NO 3) ₃ solution, the concentration of the solution used when producing a desulfurizing agent containing Fe 3 ⁺ and the Ca conversion rate of the obtained desulfurizing agent To see the correlation, a desulfurizing agent was produced by changing the Fe (NO 3) ₃ solution concentration in Example 1 under the conditions shown in Table 3, and the Ca conversion of the obtained desulfurizing agent was examined. The results are shown in Table 3 and FIG.

[Table 3]

As can be understood from the results shown in Table 3 and FIG. 2, there is a remarkable improvement over the desulfurizing agent even when a very small amount of Fe ³ + such as 10 ppm is blended. It is clear that further improvement can be expected at more than 1000 ppm.

The resulting transition metal, in particular by blending F e, further F e (NO _{₃₎ 3} solution desulfurizing agent compounded with F e ^{3 +} can experience a significantly improved desulfurizing effect and Dekitako using, desulfurization effect of improving the nitrogen oxide is presumed, the present inventors prior art proposed in the application developed, the NO _x mixed in the gas to the desulfurization process, set the circulating fluidized bed Further effects can be expected by combining the method with the desulfurization treatment. Industrial applicability

INDUSTRIAL APPLICABILITY The desulfurizing agent of the present invention is used as a desulfurizing agent having improved desulfurization characteristics in a desulfurization treatment device for waste gas from a combustion furnace, particularly a combustion furnace using coal as a fuel. In particular, as compared with the conventional dry desulfurizing agent, dry desulfurizing agent e.g. formulated with F e ^{3 +} of the present invention, especially in dry desulfurizing agent impregnated blended F e ^{3 +} with nitric acid solution, C a addition rate It has been confirmed that the desulfurization rate represented by で is improved by about 1.4 times or more, and improvement of the desulfurization efficiency leads to a decrease in the amount of desulfurizing agent used, and the application to practical equipment is improved. enable.

Claims

The scope of the claims

A desulfurizing agent containing slaked lime fine particles containing transition metal ions of I.10 or more and 100 or less ppm.

2. The desulfurizing agent according to claim 1, wherein the transition metal is iron.

3. The desulfurizing agent according to claim 2, wherein the iron ion is Fe ^{3 +} .

4. The slaked lime particles containing transition metal ions of 10 to 100 ppm or less are formed by a preparation method including the steps of charging quick lime into an aqueous solution or solution of transition metal, stirring, and drying. The desulfurizing agent according to claim 1.

5. The desulfurizing agent according to claim 4, wherein the transition metal is iron.

6. The desulfurizing agent according to claim 5, wherein the iron ion is Fe ^{3 +} .

7. A desulfurizing agent comprising slaked lime fine particles having a structure in which fine particles of slaked lime containing transition metal ions of 10 to 100 ppm and adhering to the surface of a carrier are used as desulfurizing components.

8. The desulfurizing agent according to claim 7, wherein the transition metal is iron.

9. The desulfurizing agent according to claim 8, wherein the iron ion is Fe ^{3 +} .

The slaked lime fine particles have a structure in which fine particles of slaked lime containing ions of transition metal of 10 to 10 ppm or less are adhered to the surface of the carrier. 8. The desulfurizing agent according to claim 7, wherein the desulfurizing agent is formed by a preparation method including a step of charging and stirring, a step of charging and stirring a carrier component, and a step of drying.

I I. The desulfurizing agent according to claim 10, wherein the transition metal is iron.

1 2. The desulfurizing agent according to claim 11, wherein the iron ion is Fe ^{3 +} .

13. The desulfurizing agent according to claim 7, wherein the carrier component is fly ash.

1 4. The desulfurizing agent according to claim 13, wherein the transition metal is iron.

15. The desulfurizing agent according to claim 14, wherein the iron ion is Fe ³ +.

16. The desulfurizing agent according to claim 10, wherein the carrier component is fly ash.

1 7. The desulfurizing agent according to claim 16, wherein the transition metal is iron.

18. The desulfurizing agent according to claim 17, wherein the iron ion is Fe ^{3 +} .