JPS6115740A - Regeneration of oxidizing catalyst - Google Patents

Abstract

PURPOSE:To reduce fuel cost, power cost and installation cost at the regeneration time of a catalyst, by alternately and successively changing over the flow direction of gas, which is allowed to pass through the catalyst bed used in the oxidation of a combustible component such as carbon monoxide, in a reversible manner. CONSTITUTION:In such a stage that the deterioration of a CO-oxidizing catalyst advances and the catalyst bed in the vicinity of the side of an inlet 2a is deactivated but the activity of the catalyst bed 2 in the vicinity of the side of an outlet 2b is kept, dampers 8, 8b are closed and dampers 9a, 9b are opened. At this time, exhaust gas 1 flows through the CO-oxidizing catalyst bed 2 through the dampers 9a, 9b in the direction shown by the arrow 2d opposite to a usual direction and the deactivated catalyst in the side of the inlet 2a can be regenerated by the exhaust gas 1 raised in its temp. by the catalyst bed 2 keeping activity in the vicinity of a conventional outlet 2b (the inlet at this time). The dampers 8, 8b and 9, 9a are opened and closed successively and alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for regenerating a catalyst used for oxidizing combustible components such as carbon monoxide generated in a sintered ore manufacturing process.

[Conventional technology]

Generally, unburned carbon oxide (hereinafter referred to as CO) generated in the manufacturing process of sintered ore, for example, is subject to oxidation heat recovery. Since this unburned CO has a low concentration, it is not oxidized at low temperatures, and has conventionally been oxidized using a catalyst.

However, the exhaust gas from the sintering furnace generally contains very small amounts of catalyst poisoning substances, which poses a problem in that the catalyst deteriorates. It has long been known that the regeneration of this catalyst is strongly temperature dependent, and a method has been proposed in which the catalyst is regenerated by passing high-temperature exhaust gas through the portion where the catalyst has lost its activity. For example, JP-A-56-37035, a schematic process diagram of which is shown in FIG. 5, discloses a method in which a catalyst is continuously rotated, CO gold-containing gas is passed through it, and a deteriorated catalyst is regenerated with high-temperature gas. There is.

[Problem that the invention seeks to solve]

However, in this conventional method, the oxidation heat of CO cannot necessarily be used sufficiently for catalyst regeneration, and depending on the temperature balance within the denitrification equipment system, catalyst regeneration becomes impossible. It is necessary to raise the temperature of the exhaust gas 1 and regenerate the catalyst.

Further, the rotary catalyst bed 2 has the problem that the equipment is large and the operation is complicated.

In other words, as shown in FIG. 5, the inlet temperature of the portion 12 where the activity of the catalyst has deteriorated may not reach the salinity required for catalyst regeneration, and in each case it is necessary to replenish the Co-containing exhaust gas l using the heating furnace 4. Part 1 where catalyst activity has deteriorated due to heating to M temperature
It is necessary to regenerate the second catalyst. This not only increases fuel costs but also may lead to a decrease in denitrification efficiency depending on the type of denitrification catalyst.

In addition, there was a problem in that the power consumption of the blower 5 was reduced due to pressure loss in the catalyst layer.

As a countermeasure to this problem, it is possible to reduce the thickness of the catalyst layer 2 and increase the cross-sectional area of the catalyst layer 2 to reduce the pressure loss of the catalyst layer 2, but this requires larger equipment and a larger installation area. .

The present invention was proposed in order to solve the above-mentioned problems, and all of the heat generated by the Co oxidation catalyst is effectively used for catalyst regeneration. The purpose of the present invention is to provide a method for regenerating a catalyst.

[Means for Solving the Problems] As a result of various experiments, the present inventors found that the deterioration rate of the catalyst is strongly dependent on temperature, and that a temperature gradient occurs within the catalyst layer in the direction of gas flow. It was also found that a gradient occurs in the activity within the catalyst layer. That is, as shown in FIG. 4, when the sintering furnace gas 1 passes through the Co oxidation catalyst layer 2,
Because the exhaust gas temperature rises due to the heat of oxidation of CO in the gas, the catalyst layer? A temperature gradient occurs from the inlet 2a to the outlet 2b. Adsorption of catalyst poisoning substances is strongly temperature dependent;
Compared to the adsorption rate near the inlet 2a of the catalyst layer 2, the adsorption rate at the outlet 2b
The adsorption rate in the vicinity is very small. Therefore, even at the stage where the overall catalyst activity has progressed to deterioration, the catalyst layer 2 near the outlet 2b maintains its activity.

The present inventors have discovered that by utilizing this phenomenon, it is possible to regenerate the Co oxidation catalyst by switching the fatigue of the sintering furnace exhaust gas in the opposite direction.

That is, by switching the direction of sintering furnace exhaust gas l to the opposite direction, CO oxidation occurs in the area where high activity was maintained near the conventional outlet 2b, and the υ1 gas temperature decreases by -1.
-, -J'l. This high temperature exhaust gas 1 is connected to the conventional inlet 2a.
The activity can be restored by contacting a nearby deactivated portion of the catalyst.

By sequentially switching the exhaust gas 1 at a stage when the activity near the inlet 2a decreases and the activity near the outlet 2b is maintained, the Co oxidation catalyst can be used continuously for a long period of time.

〔Example〕

Hereinafter, the present invention will be described with reference to the drawings.1. This will be explained based on an example.

FIG. 1 is a process diagram of a method according to an embodiment of the present invention, in which low-temperature exhaust gas l from a sintering furnace is heated to the denitrification reaction temperature in a heat exchanger 6, and then passed through a blower 5 when the temperature is insufficient due to the heat balance. In this case, the temperature is further raised in the heating furnace 4 to the denitrification reaction temperature, and denitrified in the denitrification reactor 3. Here damper 9,9
a is closed and dampers 8 and 8a are opened, damper 8
After that, the CO is combed in the direction of arrow 2C with the Co oxidation catalyst layer 2.
It is heated by the heat of oxidation. After passing through the damper 8a and exchanging heat with the low-temperature exhaust gas 1 in the heat exchanger 6, from the chimney 7,
released into the atmosphere.

In this process, the deterioration of the Co oxidation catalyst progresses, the catalyst layer 2 near the inlet 2a side is deactivated, and the catalyst layer 2 near the outlet 2b side is deactivated.
At the stage when the activity of is maintained, reverse i, :ri7ha8,
8a is closed and the dampers 9, 9a are opened. At this time, the exhaust gas 1 passes through the dampers 9a, 9, and reaches the Co oxidation catalyst layer 2.
flows in the opposite direction of arrow 2d. At this time, the conventional output “1”
The catalyst on the deactivated portion 2a side can be regenerated by the exhaust gas l heated in the catalyst layer 2 which maintains its activity near 2b (inlet at this time).

By sequentially opening and closing the dampers 8, 8a and 9, 9a, the Co oxidation catalyst can be used with high activity for a long period of time. Further, the reaction heat in the Co oxidation catalyst layer 2 can be used to raise the temperature of the low-temperature exhaust gas 1 to the denitrification reaction temperature by the heat exchanger 6.

Next, FIG. 2 is a process diagram of another embodiment method of the present invention, in which air is sucked by the blower 5 with valve 15 open, valve 16 closed, valve 13.13a closed, and valve 14.14a open. Co oxidation catalyst layer 2 is heated by electric heater 10.
After the temperature is raised to 90"C, the valve 16 is opened, the valve 15 is closed, and 300 Nrn'/h of exhaust gas is passed from the inlet 2a of the CO oxidation catalyst layer 2 to the "12b. At this time, the CO concentration on the inlet 2a side is The CO concentration on the outlet 2b side is sampled and measured from measurement point 18 from Ijy17 with N11 constant.When catalyst deterioration progresses, valve 14°14
A is closed, and a valve 13.13a is opened to switch the flow of the exhaust gas 1 and inject the gas 1 into the CO oxidation contact layer 2 from the outlet 2b to the inlet 2a.

FIG. 3 shows the results of implementation according to the process diagram of FIG. 2. After allowing exhaust gas to flow for a long time in advance to promote deterioration of the CO oxidation catalyst, exhaust gas 1 was sampled from measurement points 17 and 18, and the CO concentration was analyzed using a CO meter. 6 hours after the start of measurement,
Close valve 14.14a and open valve 13.13a to remove the gas residue! , l] changed. The CO concentration at measurement point 17 or 18 on the input [2a side or 2b side] was always 1.1% during the measurement period. Before switching the gas, the CO concentration at the measurement point 18 on the outlet 2b side was 0.45% (CO oxidation =
%) at measurement point 1 on the outlet 2a side after gas switching.
The CO intensity of No. 7 rapidly decreased to 0.1% (C
The O oxidation rate decreased to 91%). Exit 2b side or 2a
A lower CO concentration on the side indicates that the CO oxidation rate of the CO oxidation catalyst is good, indicating that the activity of the CO oxidation catalyst has been recovered. Further, at the 9th hour, valve 14.14
A was opened and valve 13.13a was closed to restore the flow of exhaust gas 1, but the CO concentration on the outlet 2b side was 0.1%. Also CO
The oxidation catalyst maintained high activity. From the above experiments, it was confirmed that the CO oxidation catalyst was regenerated by switching the flow of the exhaust gas 1.

Note that the present invention is not limited to the case of oxidizing carbon monoxide in sintering factory exhaust gas.

〔Effect of the invention〕

As described above, according to the present invention, all of the heat generated by the CO oxidation catalyst is effectively used for catalyst regeneration, and the catalyst is continuously regenerated. In addition, by reversing the direction of the gas flow, the temperature of the catalyst on the gas inlet side before switching increases to the temperature required for catalyst regeneration, allowing the deteriorated catalyst to be regenerated quickly and completely. All of the heat generated by the CO oxidation catalyst is effectively used for catalyst regeneration, reducing fuel costs. Furthermore, in contrast to conventionally proposed methods, according to the method of the present invention, since the linear velocity of the gas is small, it is possible to reduce the amount of electric power used without requiring a large capital investment. Furthermore, since the catalyst is not moved, the structure of the device is simple and the physical strength of the catalyst is not required.

[Brief explanation of drawings]

Fig. 1 is a process diagram of one embodiment of the present invention, Fig. 2 is a process diagram of another embodiment of the present invention, Fig. 3 is an explanatory diagram of the implementation results of Fig. 2, and Fig. 4 is a process diagram of the present invention. FIG. 5 is a process diagram of the conventional method. 1... Sintering furnace exhaust gas 2... Catalyst layer 3... Denitration reactor 4... Heating furnace 5... Blower 6... Heat exchanger 7... Chimney 8.8a, 9. 9a...Damper 10...Electric heater 13.13a, 14.14a, 15, 16-...Valve 17.18...Fllll fixed point

Claims (1)

[Claims] A method for regenerating an oxidation catalyst, comprising sequentially switching the flow direction of gas passing through a catalyst layer used for oxidizing combustible components such as carbon monoxide between forward and reverse.