JPS6214924A - Denitration apparatus having catalyst regeneration apparatus incorporated therein - Google Patents

Abstract

PURPOSE:To decompose and remove acidic ammonium sulfate being precipitated and adhered by guiding exhaust gas raised in temp. to a catalyst bed from the temp. raised gas injected pipe of a flow passage of which the damper is closed, by providing the dampers of a plurality of flow passages in a reactor, a temp. raised gas injection apparatus and a catalyst bed. CONSTITUTION:The inlet damper 7-1 of one section 6-1 of a reactor 1 is closed. NH3 is injected in a main duct 12 from the NH3 injection nozzle 3 provided to said main duct 12 and the temp. of bypassed exhaust gas B containing NH3 is raised to acidic ammonium sulfate decomposition temp. by a temp. raising apparatus 4 and this temp. raised gas C is injected in the section 6-1 by a temp. raised gas injection pipe 8 to simultaneously perform the regeneration of a catalyst bed 2-1 and the denitration of the temp. raised gas C. After regeneration treatment is finished, the injection of the temp. raised gas C is stopped and, when a damper 7-1 is opened, the section 6-1 returns to usual denitration. Succeedingly, the same operation is repeatedly performed in other section.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a denitrification device, and more particularly to a denitrification device that can simultaneously denitrate exhaust gas and regenerate a catalyst.

[Prior art and problems to be solved] Son'
The denitrification method of exhaust gas contains NH.

This method involves injecting NH3 into the denitrification reactor and denitrating it in a catalyst layer. However, when using low-temperature exhaust gas, the NH3 injected from the NH3 injection nozzle reacts with 803 in the exhaust gas. The generated acidic ammonium sulfate (NH4H8O4) deposits and adheres to the catalyst layer, significantly impairing the denitrification performance.

Conventionally, there have been two methods: (1) installing an exhaust gas temperature riser on the upstream side of the denitrification reactor to raise the temperature of the entire amount of exhaust gas above the precipitation temperature of acidic ammonium sulfate, and denitrating in a temperature range where acidic ammonium sulfate is not generated; A method was adopted in which the exhaust gas temperature was raised to the acidic ammonium sulfate decomposition temperature using an exhaust gas heating device every period, and the catalyst was heated.

However, all of these methods have the following problems.

In other words, in the method (■) above, the running cost is extremely high because the temperature of the entire amount of exhaust gas is constantly raised.
Large-capacity equipment is required.

In addition, in the method (2) above, the exhaust gas heating cost increases because all the catalyst layers are regenerated at once, large-capacity heating equipment is required, and furthermore, all the catalyst layers are regenerated at once. There are problems such as large amounts of SO3 and NH3 being emitted from the chimney to decompose the acidic ammonium sulfate adhering to the layer.

In order to deal with these problems, we are considering a method of removing part of the catalyst layer from the reactor and regenerating it, but the
Another problem arises in that it must be temporarily suspended.

Incidentally, the problems with the method (2) above will be explained in more detail.

Is there a system diagram of a general denitrification device with an exhaust gas heating device related to this method? It is shown in FIG. In the figure, catalyst # is inside reactor l.
2 is filled, and the duct (11) on the upstream side is filled with NH
, an injection nozzle 3 and an exhaust gas heating device 4 are installed.

In this system, SOs at low temperature? : When the contained exhaust gas A flows through the duct 11, NH, NHs injected from the injection nozzle 3, and SO3 contained in the exhaust gas A react, and acidic ammonium sulfate (NH4H8O4) is deposited on the catalyst layer 2. This results in a decrease in denitrification performance. Therefore, at regular intervals, the temperature of the exhaust gas A is raised to a temperature higher than the decomposition temperature of acidic ammonium sulfate using the temperature raising device 4 to decompose and remove it, and the catalyst is regenerated as shown in line 9. However, increasing the temperature of all the exhaust gas flowing through the reactor 1 increases running costs, and furthermore, since the acidic ammonium sulfate deposited on the catalyst layer 2 is decomposed at once, a large amount of exhaust gas flows from the chimney 5. 803 and N l(s is discharged at once t,
This will cause secondary pollution.

For the reasons mentioned above, it has been desired to develop a low-temperature denitrification system that is inexpensive and has high performance.

The purpose of the present invention has been made to meet the above-mentioned demands, and it is capable of solving the drawbacks of the prior art described above, being inexpensive and having low running costs, and also being capable of catalyst regeneration while performing denitrification. Sometimes secondary pollution? The purpose of the present invention is to provide a denitrification device that has no negative effects.

[Means for solving problems]

In order to continuously achieve the above purpose, the denitrification device according to the present invention divides the interior of the reactor into a plurality of flow passages, and each section is provided with a damper that can be opened and closed, a heated gas injection pipe, and a catalyst layer. By installing a heating device in the bypass duct that branches from the upstream side of the section, the exhaust gas heated in the bypass duct is guided to the catalyst layer through the heating gas injection pipe of the section closed by the damper, and the acid that has deposited is removed. It is constructed to decompose and remove ammonium sulfate.

The invention below? A detailed explanation will be given based on the illustrated embodiment.

〔Example〕

1 and 2 are system diagrams of a denitrification apparatus according to an embodiment of the present invention. In FIG. 1, a reactor 1 is connected to a plurality of sections 6.
Each section 6 is provided with an inlet damp buff and a heating gas injection pipe 8, and is filled with a catalyst layer 2.

The heated gas supplied to the heated gas injection pipe 8 is supplied by a bypass duct 9 branched from the main duct 12 on the front R side of each section 6. A heating device 4 is provided to raise the temperature of the exhaust gas in the duct and to supply it by a fan IO. The amount of gas passing through the bypass duct 9 can be adjusted to match the amount of catalyst to be regenerated, and the amount of gas supplied to each section not undergoing regeneration is always constant. This effect will be described later. When regenerating the catalyst, as shown in FIG. NH3 is injected from nozzle 3, bypassed and 1 NH3'l
The temperature of the exhaust gas Bg containing Bg is raised to the acidic ammonium sulfate decomposition temperature by the temperature raising device 4, and this heated gas C'! ' Heating gas injection pipe 8
-1 is injected into section 6-1, and regeneration of catalyst N2-1 and denitrification of heated gas C are performed simultaneously. At that time, in order to raise the temperature of the bypass exhaust gas B with the exhaust gas temperature raising device 4 provided in the bypass duct 9, the treatment W-j is heated in the section 6-1.
The gaff t increases due to thermal expansion, but since the increase in catalyst performance due to temperature rise is generally large, is it necessary to determine the required performance? :# It is possible to add.

Next, after the regeneration process is completed, the injection of the heated gas C is stopped, and when the damper 7-IFa' is opened, the section 6-1 returns to normal denitration. Next, the other section 6-2.6
-3... The same operation is repeated in sequence.

According to the simultaneous denitrification and regeneration method having the above configuration, the catalyst layer 2 to be regenerated can be divided into smaller portions, so the amount of heated gas C can be reduced, and the amounts of SO2 and NHa generated during acidic ammonium sulfate decomposition are also small. Furthermore, there is also the effect of reducing the amount of catalyst used.

In other words, Figure 3 shows the relationship between the denitrification rate and the elapsed time when the same reactor is operated using three methods. E) and the change in the denitrification rate with respect to the operating time for the simultaneous denitrification and regeneration method CF) according to the present invention? Shown schematically. As can be seen from the figure, the temperature raising method (D) has stable performance, but has the drawback that, as mentioned above, a large amount of sintering cost is required to raise the temperature of the entire exhaust gas. In addition, the total amount of exhaust gas simultaneous regeneration method (E) has a drawback that the amount of catalyst used increases because the range of change in the denitrification rate is extremely large and the amount of catalyst is determined based on the lowest denitrification rate. Compared to the above two methods, the simultaneous denitrification and regeneration method (F) according to the present invention has the advantage that the range of change in the denitrification rate is small, stable denitrification performance can be obtained, and at the same time, the amount of catalyst required is small.

Furthermore, in the simultaneous denitrification and regeneration method according to the present invention, in order to adjust the amount of gas passing through the bypass duct to the amount of gas commensurate with the amount of catalyst in each section, the amount of gas passing through the catalyst layer used for denitration treatment is is constant 65 regardless of whether or not the catalyst is regenerated, so that while the catalyst is regenerated in one section, the denitrification process can be performed simultaneously in the other section.

Next, FIG. 4 shows another embodiment 1 of the present invention. In particular, when the temperature raised by the exhaust gas temperature raising device 4 in the bypass duct 9 reaches a very high temperature, it is recommended to install an NH injection pipe 3Y in the main duct 12 on the upstream side of the bypass duct 90 branch point.
(Fig. 1), N Hs contained in the exhaust gas decomposes, and N
There is a risk that it will be converted to Ox. In order to prevent this, the NHs injection pipe 3'a' provided in the main duct 12 is installed on the downstream side of the branch point of the bypass duct 9, and also on the downstream side of the exhaust gas temperature raising device 4 of the bypass duct 9. NH3
It is recommended to add 3 injection tubes. Note that the other configurations in FIG. 4 are the same as in FIG. 1.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, catalyst regeneration can be performed while denitration is being performed.

The cost of raising the exhaust gas temperature is low, and the increase in 803 and NH3 on the downstream side of the reactor that occurs during catalyst regeneration can be suppressed.

Furthermore, since the range of change in the denitrification rate is small, the amount of catalyst used can be reduced, and equipment costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a denitrification device according to an embodiment of the present invention, and FIG. 2 is a partially detailed explanatory diagram of the system diagram in FIG. 1. FIG. 3 is a diagram showing the relationship between denitrification rate and operating time in various denitrification and regeneration methods, and FIG. 4 is a system diagram of another embodiment of the present invention.
FIG. 5 is a system diagram of a conventional denitrification device equipped with an exhaust gas temperature raising device. 1... Reactor, 2... Catalyst layer, 2-1,...2-
5...Catalyst layer section, 3.3'...NH, injection pipe, 4...Exhaust gas temperature raising device, 5...Chimney, 6.6-
1. ..., 6-5...reactor section, 7.7-
1,..., 7-5... Enter Rodanba, 8.8-1,...
..., 8-5... Temperature rising gas injection pipe, 9... Bypass duct, 10... Fan, 11... Duct, 12.
・Main duct.

Claims (1)

[Claims] (1) In a denitrification device that denitrates exhaust gas led from a duct with a catalyst layer in a denitrification reactor and regenerates the catalyst by raising the temperature of the exhaust gas when necessary, the inside of the denitrification reactor is formed into a plurality of flow channels. A damper that can be opened and closed is provided at the inlet of each section, and a heated gas injection pipe and a catalyst layer are also provided, and a bypass duct is branched from the undivided main duct on the upstream side of all sections. 1. A denitrification device incorporating a catalyst regeneration device, characterized in that an exhaust gas temperature raising device is provided in the denitration device, and the heated exhaust gas is supplied to each of the heated gas injection pipes.