JPS6347506B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a denitrification catalyst installed in a vertical flow type denitrification reactor while it is still installed in the apparatus.

The denitrification performance of the denitrification catalyst incorporated in the denitrification reactor deteriorates over time. This is caused by various poisonous components that occur over long-term use, such as adhesion of alkali metals to the catalyst in boiler exhaust gas treatment using C heavy oil, or adsorption of dust containing organic matter in the exhaust gas. .

Catalysts whose denitrification performance has deteriorated lose their practical effectiveness, so it is necessary to dispose of them or take measures for economical regeneration.

The method of regenerating this catalyst that has been proposed in the past is a method of firing at 700 to 800°C (Japanese Patent Application Laid-open No.
153787), and a method of calcination at 100 to 500℃ after washing with water (Japanese Patent Application Laid-Open No. 153789), both of which are recognized as effective, but in order to carry out these methods, a denitrification reaction device is required. The denitrification catalyst must be taken out from the tank, which not only requires a very long process time but is also economically disadvantageous.

The present invention has been made to eliminate such drawbacks, and provides a method for regenerating a catalyst whose denitrification performance has deteriorated while it is still installed in a denitrification reactor.

In other words, the present invention cleans a denitration catalyst that has deteriorated over time and is installed in a vertical flow type denitrification reaction device by cleaning the appearance of the catalyst by using a water washing device consisting of a permanent part and a temporary part while the denitration catalyst is installed in the equipment. of volume
A step of washing with 10 times the amount of water, a step of discharging the washed water out of the system from a drainage hopper permanently installed at the bottom of the reaction device or an air heater section at the bottom of the reaction device, and a step of introducing compressed air after the washing is completed to The present invention relates to a method for regenerating a catalyst, which comprises a step of removing moisture remaining in the catalyst, and a step of drying the catalyst using a boiler heat source or exhaust gas at a temperature of 120° C. or higher when the boiler is fired.

Hereinafter, the method of the present invention will be explained in detail with reference to the accompanying drawings.

Figures 1A and B and Figures 2A and B are diagrams showing examples of vertical flow type denitrification equipment according to the method of the present invention, and Figures 1A and B flow the gas G to be treated from the upper part of the equipment to the lower part of the equipment. Figure 2 A and B are of the downstream type, and Figures 2A and B are of the upstream type in which the gas to be processed G flows from the bottom of the device to the top of the device.
It is a line arrow view.

In Figure 1 A, B and Figure 2 A, B, 1
2 is a vertical flow type denitrification reactor main body, and 2 is a shaped steel catalyst pack incorporated in the device 1, which is filled with several tens to hundreds of denitrification catalysts. 3 to 10 are parts related to the flushing device according to the method of the present invention, where the main water supply pipe 3, gate valve 5, pressure gauge 6, and intake port 10 are permanently installed, and the flexible hose 4, water supply pipe 7, nozzle header 8, and nozzle 9 are temporary parts. part, 11-1
3 is a drainage means according to the method of the present invention, 11 is a drainage hopper permanently installed in the above-mentioned downstream type reaction apparatus 1, and 12 is an air heater section originally installed in the above-mentioned upstream type reaction apparatus 1. The valve 13 is used as a drainage hopper as it is.

In the above-mentioned water washing apparatus, a temporary part is first assembled within the reaction apparatus prior to the water washing operation. That is, the nozzle header 8 is positioned on the upper surface of the catalyst pack 2 (about 300 to 500 mm in height) and set so that the nozzle 9 is perpendicular to the catalyst. On the other hand, a flexible hose 4 is connected to the main water supply pipe 3, inserted into the reaction apparatus 1 through the inlet 10, and connected to the water supply pipe 7.

After completing the above assembly, perform a water washing operation.

In the water washing operation, the gate valve 5 is gradually opened, the water pressure is adjusted to 2 to 3 kg/cm ² using the pressure gauge 6, and atomized water is injected from the nozzle 9 onto the catalyst. The amount of water injected is set to be 10 times the apparent volume of the catalyst in order to perform water washing effectively and to minimize washing wastewater. The injected water passes through the drainage hopper 11 or the air heater section 12 and is extracted from the drainage valve 13. The washing time should be set until the concentration of poisonous substances such as alkali metals in the waste water reaches almost zero.

When this water washing operation is completed, compressed air at a pressure of about 4 to 5 kg/cm ² is introduced from the main water supply pipe 3 to remove moisture remaining in the catalyst pack 2. This water removal operation is generally carried out for 5 minutes or more, preferably 10 minutes or more, until water drops no longer fall from the catalyst pack 2.
Do this for more than a minute. If the catalyst is dried using hot air from a boiler heat source (described later) or exhaust gas having a temperature of 120° C. or higher when the boiler is fired without performing this moisture removal operation, there is a risk that the catalyst will be damaged.

Thereafter, the nozzle header 8, nozzle 9, and water supply pipe 7 are moved to the parts of the catalyst pack 2 that have not been washed yet as shown in FIGS. 1A and B and 2A and B, and the nozzle header 8 is positioned as described above. Then, the nozzle 9 is made vertical, and the water washing operation and water removal operation are performed as described above.

After performing the above operations on all catalyst packs 2 and washing with water is complete, remove the temporary part of the water washing device and remove the heat source of the boiler, such as the steam air preheater (SAH), fan (FAN), forced draft fan, etc. (FDF), hot air from the air preheater (AH), or exhaust gas at a temperature of 120° C. or higher when the boiler is fired is passed through the path of the gas to be treated G in the reaction device 1 for drying. As the exhaust gas when firing the above boiler, 120℃
The reason for using a temperature higher than 120℃ is that a temperature of 120℃ or higher is required to evaporate and scatter the water adhering to the catalyst (the hot air from the boiler heat source mentioned above is generally 120℃ or higher temperature). Furthermore, since high-quality fuel such as diesel oil is used when firing the boiler, the catalyst is not poisoned by the exhaust gas much, and a small amount of SOx contained in the exhaust gas adheres to the catalyst, causing the SOx to become a co-catalyst. The effect restores the performance of the regenerated catalyst to almost the same level as a new catalyst.

In accordance with the above operation mode, a denitrification catalyst whose initial performance had dropped to 78% was regenerated, and the performance was recovered to 87%.

At this time, the properties of the gas to be treated before and after regeneration were as follows: Gas temperature: 385°C Gas composition: Inlet NOx 100ppm Inlet SOx 110ppm, and the water washing conditions, water removal conditions, and drying conditions were as follows. did.

Washing conditions Water quality: Industrial water Amount: Water 10 times the apparent volume of the catalyst Temperature: Room temperature Time: 1 hour Moisture removal conditions Air used: 4.5 Kg/ ^cm2 compressed air Time: 7 minutes Drying conditions Heat source used : When firing a boiler using light oil
Exhaust gas at 120°C Time: 1 hour In addition, the above denitrification performance indicates the denitrification rate determined by the formula below.

Denitration rate = inlet NOx concentration - outlet NOx concentration / inlet NOx concentration (however, all NOx concentrations are O ₂ 4% equivalent values) As detailed above, according to the method of the present invention, the denitrification catalyst is It can be regenerated while being installed in the reactor, the time required for regeneration is extremely short, and it is extremely advantageous economically.

[Brief explanation of the drawing]

1A and 2B and 2A and 2B are diagrams showing examples of vertical flow type denitrification reactors according to the method of the present invention,
In each figure, B is a sectional view, and A is a view of B taken along the line AA.

Claims (1)

[Claims] 1. In a method for regenerating a denitrification catalyst installed in a vertical flow type denitrification reactor, the catalyst is removed by 10 times the apparent volume of the catalyst using a water washing device consisting of a permanent part and a temporary part while the catalyst is installed in the equipment. a step of discharging the washed wastewater out of the system from a drainage hopper permanently installed at the bottom of the reaction device or an air heater section at the bottom of the reaction device; and a step of introducing compressed air into the catalyst after the washing is completed. A method for regenerating a catalyst comprising the steps of: removing moisture remaining in the catalyst; and drying the catalyst using a boiler heat source or exhaust gas at a temperature of 120° C. or higher when the boiler is fired.