JPS6261647A - Method for regenerating denitration catalyst - Google Patents

Abstract

PURPOSE:To enhance the regeneration effect of the denitration catalyst for a garbage incinerator, by removing the surface of the part contacted with gas to be treated of an ammonia catalytic reducing denitration catalyst lowered in its catalytic activity by abrasion and subsequently washing the abraded surface with water. CONSTITUTION:A columnar containe 1 such as a drum, from which a lid 3 was removed, is packed with an ammonia catalytic reducing denitration pellet catalyst (containing 89wt% of TiO2 and 11wt% of V2O5 and having a diameter of 4-6mmphi) lowered in its activity so as to occupy 40-60% of the volume of said container 1 and the lid 3 is subsequently applied to the container 1. The container 1 is then rotated at 60rpm for about 60min to contact catalyst particles with each other to abrade the surfaces of said catalyst particles, and, after the abrading treatment, the catalyst particles are immersed in water 8 times by volume of the catalyst for about 60min while stirring is performed occasionally. If this method is adapted to the denitration catalyst for an urban garbage incinerator, the regeneration effect is markedly displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for regenerating a pellet-like (granular, cylindrical) catalyst applied to a flue gas denitrification device.

[Conventional technology]

As a method for removing nitrogen oxides from combustion exhaust gas, an ammonia catalytic reduction method in which ammonia is used as a gold reducing agent and reduced by a catalyst is widely used.

These ammonia catalytic reduction denitrification catalysts (hereinafter referred to as denitrification catalysts or simply catalysts) for removing nitrogen oxides maintain high denitrification performance because their performance gradually decreases when used in combustion exhaust gas. For this purpose, it is necessary to replace the catalyst or reactivate the catalyst whose performance has deteriorated.

However, replacing a catalyst whose performance has deteriorated with a new catalyst is economically disadvantageous because the catalyst is expensive and disposal of the used catalyst also costs t-. Therefore, it is advantageous to reactivate and reuse a catalyst whose performance has deteriorated.

Pellet catalysts are applied to boilers for LNG-fired exhaust gas and municipal waste incinerators, and the inventors have found that in the latter case, compounds such as silica, iron, aluminum, calcium, magnesium, sodium, and potassium adhere to the catalyst surface. It was discovered that the performance deteriorated due to the accumulation of alkaline components such as sodium and potassium inside the catalyst. When applied to normal heavy oil-fired boiler exhaust gas, catalysts whose performance has deteriorated can be regenerated by washing with water (water washing treatment) to elute alkaline components such as IJum and potassium that have accumulated on the catalyst. However, the dust component in the exhaust gas from municipal waste incineration boilers is different from the main component (80~? Ovtl) in the exhaust gas from ordinary heavy oil-fired boilers, which is unburned carbon. Pa.

Elements such as MuL, OA, Mg, Zn, Ma, and K exist in the form of chlorides, sulfates, phosphates, and compounds9, and some of these compounds are
Some substances adhere to the surface of the catalyst due to their properties, and it is difficult and requires a large amount of water to remove them only by washing with water. For the above reasons, simply washing with water is not enough.
<Recovery rate cannot be obtained. If a large amount of water is used for water washing, problems with wastewater treatment will naturally arise.

[Problem that the invention seeks to solve]

The reason for the performance deterioration of catalysts applied to exhaust gas from municipal waste incinerators is not only the accumulation of alkaline components such as sodium and potassium on the catalyst, as in the case of catalysts applied to ordinary heavy oil-fired boiler exhaust gas, but also water adhering to the catalyst surface. Because poorly soluble substances are also involved, a satisfactory recovery rate cannot be obtained simply by washing with water.

The present invention seeks to provide a satisfactory method for regenerating such degraded denitrification catalysts.

[Ninth way to solve the problem]

The present invention is a method for regenerating a denitrification catalyst, which is characterized in that the surface layer of the ammonia catalytic reduction denitrification catalyst that has deteriorated in performance is washed with water after abrasion is removed from the surface layer of the part of the catalyst that comes into contact with the gas to be treated.

[Effect]

In the present invention, the performance deteriorates and the very surface of the pellet-like denitrification catalyst is worn out, and then silica, iron, aluminum, etc.
It removes dust components such as calcium, magnesium, sodium, and potassium (14) and exposes a new catalyst surface, thereby increasing the effectiveness of washing the catalyst with water.

The inventors discovered the compound form 11 F1 of the component that accumulates in the catalyst.
a 10x e ICt Ss Os e M a 0
4K O4Ca COs and Oa 804 were confirmed by X-ray diffraction analysis, and they were found to be concentrated on the extreme surface of the catalyst9.

A greater recovery rate can be obtained by removing these surface deposits by abrasion treatment and then applying water washing treatment.

In addition, after the abrasion treatment, water washing treatment is performed to perform wastewater treatment 1.
Another feature is that cages can be reduced.

〔Example〕

Under the initial Mox removal removal plate, 810s of pelleted denitrification catalyst (described as denitrification force) was used in the exhaust gas of a municipal waste incinerator.
After 9,000 hours of filling, the denitrification value decreased to 310-.

The same catalyst with degraded performance was subjected to abrasion treatment and water washing treatment using the two methods shown below, respectively, and its performance was evaluated. We conducted a performance evaluation using only water washing treatment.

Furthermore, the author of this catalyst is rio! 89 vt%%-to11
In Wt4j, the catalyst diameter is 4 to 6 mm.

Wear treatment was carried out in the following manner.

(1) As shown in FIG.
After taking ``Ik'' and filling with light for 4 to 6 minutes, and closing the lid 3, the container 1 was rotated to completely abrade the catalyst surface by contact between the catalysts.The rotation speed was 60 rpm and the container was rotated for 60 minutes.

After this abrasion treatment, the catalyst gold was immersed in water of 8 times the volume of the catalyst for 60 minutes with occasional stirring. A container consisting of a cylindrical mesh 5 is filled with pellet catalyst 7 for 4 to 6 minutes, the lid 6 of the mesh 5 is put on, and the pellet is placed in a cylindrical container 9.

As before, the catalyst is rotated once to wear it out, but the cylindrical net 5 is equipped with a floating plate 8 so that the worn catalyst powder does not remain between the catalysts, making post-treatment convenient.

This was also rotated for 60 minutes at a rotation speed of 6° rpm, and then the above (
A water washing treatment was performed under the same conditions as in 1).

For catalysts that were only washed with water, the process of water washing and evaluation was repeated three times. The washing conditions are the same as above.

As described above, we evaluated the performance of the catalyst at n-t';rt and compared it with the performance before treatment.In order to evaluate the catalyst, we used it on a small catalyst evaluation device that can be made at the same temperature and gas composition as the catalyst filling conditions in the actual device. 90 The conditions are shown in Table-1.

Table 1 Catalyst evaluation results are shown in Table 2. Here, the recovered catalyst refers to the denitrification curtain of the new catalyst: FI7 The denitration curtain after regeneration treatment: R? , if the denitrification curtain t)+7 before the regeneration process, then ((R wa Uη)/
CF+7-11117))

Table-2 In the case of water washing II & salt only regeneration, after the first water washing, the round return is 3 and 5 chi, and after the second water washing, the bolt is atos%3E.
The same s'host is shown on the mth page.

Figure lE1 and Figure 2 01! After the abrasion treatment with the equipment, water washing treatment was performed, and the recovery rate was 5cLo* and 5tost.

Based on this result, wear treatment was performed by washing with water at 2
r! It has an effect equal to or greater than the ability to restore
During the minute recovery treatment process, the wastewater treatment process was proven to be hot in the tS maple.

In addition, the abrasion of the catalyst surface layer in the process shown in Figure 1 and the process shown in Figure 2 is 40 pm, calculated from the catalyst weight, catalyst density, etc.
, 70 μm.

〔Effect of the invention〕

When regenerating a pellet catalyst whose performance has deteriorated by washing with water, the regeneration effect will be greater if the abrasion treatment is first performed and then the water washing treatment is performed.

When this was applied to a denitrification catalyst for municipal waste incinerators, the effect was noticeable. It also reduced the wastewater treatment process during washing.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing a container used for the abrasion treatment of the present invention. Sub-Agents 1) Meifuku Agent Ryo Hagiwara - Sub-Agent Atsuo Anzai Figure 1

Claims (1)

[Claims] A method for regenerating a denitrification catalyst, which comprises abrading and removing the surface layer of the part of the ammonia catalytic reduction denitrification catalyst that comes into contact with the gas to be treated, which has deteriorated in performance, and then washing the catalyst with water.