JPH04326924A - Intermittent type apparatus and method for purifying catalyst - Google Patents

Abstract

PURPOSE:To provide the apparatus reduced in energy loss and effective even for corrosive gas in a catalyst purifying apparatus heating harmful components such as CO (carbon monoxide), HC(hydrocarbon) or the like in various exhaust gases to oxidize and purify the same. CONSTITUTION:The opening end of a catalyst purifying apparatus main body having two chambers mutually communicating at closed other ends thereof and each having a catalyst and a heating device can be alternately converted as an exhaust gas inlet or outlet and corrosion-resistant heat accumulator layers are respectively arranged on the way of the exhaust gas flow passages from the opening end to the catalysts or heating devices. Exhaust gas receives heat from one of the heat accumulator layers to be purified in a heated state and the heat thereof is removed by the other heat accumulator layer to discharge the exhaust gas in a cooled state. By reversing the flow of the exhaust gas to be treated at every set time, the respective heat accumulator layers alternately develops heating and cooling functions. By this constitution, a part or the greater part of heat energy for heating exhaust gas to temp. necessary for purifying the gas can be circulated in the catalyst purifying apparatus main body and thermal loss can be reduced even by intermittent operation. Further, this apparatus can be adapted to corrosive gas.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a catalytic purification method that heats malodorous and harmful components such as CO (carbon monoxide) and HC (hydrocarbons) mixed in various exhaust gases to an appropriate temperature and oxidizes them using a catalyst. The present invention relates to a device and a purification method, and provides an intermittent catalyst purification device particularly suitable for purifying harmful gases that are generated intermittently.

0002

BACKGROUND OF THE INVENTION In recent years, it has become essential to purify and discharge CO and HC components generated in various combustion machines, drying, and heat treatments due to their toxicity and odor. In addition, harmful gases are generated when using band machines and fusing resins, vinyl, etc., and there is a need to purify them.

[0003] As a method for purifying CO and HC components, a method of heating the exhaust gas itself and causing it to react with oxygen in the gas has the highest purification efficiency and reliability. In order to raise the temperature of the exhaust gas and cause the oxygen in the air to react with CO and HC, it takes 800
A temperature of ~900°C or higher is required. However, if an oxidation catalyst is used, the reaction can proceed in a temperature range of 200 to 400°C, and waste of thermal energy can be avoided, so it is widely used.

[0004] A conventional catalyst purification device will be explained below. FIG. 4 is an example of a conventional catalyst purification device, and (a)
(b) shows the catalytic purification device main body, and (b) shows the system including heat exchange. In the figure, 19 is the main body of the catalyst purification device, 16 is a heat exchanger, 12 is a heating device, and 13 is a catalyst. In (a), exhaust gas is introduced into the catalyst heating device main body from the inlet 20,
The temperature is raised to a predetermined temperature by the heating device 13, and CO, HC, etc. are oxidized and purified by the catalyst 13, and then discharged from the outlet 14. At this time, the energy required to raise the temperature of the exhaust gas is exhausted together with the gas. A system using a heat exchanger for the purpose of recovering part of this energy is shown in (b). In this case, the exhaust gas introduced from the gas inlet 17 and heated by the heat exchanger 16 flows along the arrow and advances to the main body of the catalytic purification device 19. The gas purified here again enters the 16 heat exchangers, is cooled, and is discharged from the gas outlet 18. In other words, it attempts to recover a portion of the energy required to raise the temperature of exhaust gas and reduce energy loss.

[0005]

[Problems to be Solved by the Invention] However, the heat exchanger 16 used in the above-mentioned conventional configuration is usually made of thin-walled aluminum with good thermal conductivity, and the heat exchange efficiency is limited to 50 to 60%. be. Further, aluminum could not be used for exhaust gas containing corrosive gases such as SOx and NOx because the aluminum would corrode. Moreover, there is a problem in that it is necessary to constantly operate to purify harmful gases that are generated intermittently, and there is a lot of energy waste.

The present invention solves the above-mentioned conventional problems, and greatly reduces energy loss by greatly improving heat exchange efficiency. It is also effective against corrosive gases, and is particularly effective against intermittent gases. The purpose is to provide a catalyst purification device and a purification method that are effective for operation.

[0007]

[Means for Solving the Problems] In order to achieve this object, the intermittent catalyst purification device of the present invention has a structure in which one end of the main body is open and the other end is closed, and two chambers communicate with each other at that part. A heat storage layer is placed on the opening side of each chamber, and a catalyst and a heating device are placed on the closed side, and the opening of each chamber is connected to an exhaust gas inlet flow path via a damper. and an outlet flow path.

[0008]

[Operation] Purification of exhaust gas by this configuration will be explained. The two chambers of the purifier main body operate in a state where they are in communication with only one of the opposing outlet or inlet gas flow paths. Exhaust gas containing malodorous components flows into one chamber from the inlet gas flow path, is heated by a heat storage body and a heating device, and then purified by a catalyst. Then, when the exhaust gas passes through the heat storage body in the other chamber, the energy of the exhaust gas is taken away by the heat storage body, and the exhaust gas is cooled and discharged to the exit gas flow path. Next, the flow of exhaust gas within the purifier body is reversed by switching the dampers in each chamber simultaneously. That is, the chamber that has been in communication with the outlet flow path will now be in communication with the inlet flow path, and the chamber that has been in communication with the inlet flow path will be in communication with the outlet flow path. At this time, the exhaust gas is heated by absorbing heat from the heat storage body, which has absorbed sufficient thermal energy. Then, it is purified by the catalyst, cooled by the other heat storage layer, and discharged. This means that part or most of the thermal energy needed to heat the exhaust gas to the temperature required for purification can be circulated inside the catalyst purification system, reducing the thermal loss of exhaust gas. means. In addition, while the exhaust gas is not flowing through the heat storage body, only the heat released from the outermost wall of the catalyst purification device body appears as thermal loss, and it can demonstrate sufficiently high energy efficiency even in intermittent operation. . If a ceramic structure with a large heat capacity and excellent corrosion resistance is selected as the material for the heat storage body, it is possible to provide a catalytic purification device that can purify even exhaust gas containing corrosive substances and has little thermal loss.

[0009]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numerals 1 and 2 indicate flow paths on the inlet side of exhaust gas, and reference numeral 11 indicates flow paths on the outlet side of exhaust gas. 7 is a catalytic purification device main body, 6 is a heat storage layer, 9 is a catalyst, and 10 is a heating device. (a) is a schematic diagram of the device, (b) is (a)
A cross section taken along A-B plane is shown. The upper part of (b) is the opening, which communicates with the inlet side flow path and the outlet side flow path through the damper parts 4 and 5. The lower part shows one end that is closed, and the two chambers on the left and right, separated by 8 dividing walls, communicate here. The flow of exhaust gas is indicated by arrow 3. 4 indicates a closed damper and 5 indicates an open damper. (c) and (d) are (a) and (
This shows a state in which the flow of exhaust gas is reversed from state b) by operating the damper.

Next, states (a) and (b) will be explained. Exhaust gas containing harmful gas enters from entrance 1 in (a),
Proceeding to the left, it passes through the opening 5 from the arrow and is introduced into the catalyst purification device main body 7. Here, the exhaust gas flows as shown by the arrow in (b). At this time, it is heated by the heat storage layer 6 in the left chamber, and the harmful gas is purified by the catalyst 9 and heating body 10 in the left and right chambers. Then, heat is exchanged in the heat storage layer 6 of the right chamber, and the cooled state is discharged from the opening 5 to the outlet side flow path 11. After a certain period of time, the flow of exhaust gas is stopped and the damper is operated to achieve the conditions (c) and (d), and the exhaust gas is allowed to flow again. At this time, the exhaust gas flows to the right through the inlet side flow path 1 in (c), flows from top to bottom through the right chamber in (d), moves to the left chamber, where it flows from bottom to top, and flows through the outlet side flow path. It is discharged at 11. The heat storage layer 6 of the right ventricle has sufficiently stored thermal energy in the state (b), and heats the exhaust gas by heat exchange in the state (d). That is, thermal energy is circulated within the catalyst purification device, and the amount lost is extremely small.

Table 1 shows the results of measuring the harmful component purification effect and thermal efficiency in this example.

[0013]

[Table 1]

The catalyst purification device has 5 liters of granular alumina (5 to 10 mmφ) in each chamber as a heat storage body, 1 liter of honeycomb-shaped platinum catalyst as a catalyst,
The heating device uses a sheathed heater with a maximum capacity of 1kW.
Temperature control was performed at 0°C. The exhaust gas contained 100 ppm of styrene gas, and the air flow rate was 500 liters/min. The purification rate of exhaust gas is indicated by the decomposition rate of styrene gas by a catalyst, and thermal efficiency is simply calculated by assuming that the exhaust gas is heated to 300℃ and comparing the difference between the outlet temperature and the inlet temperature with respect to the temperature raised to 300℃. Calculated. What is switching time?
It shows the time that exhaust gas continues to flow in one direction, and when the damper is switched, the exhaust gas does not flow for 10 seconds.

[0015] As is clear from Table 1, the catalytic purification apparatus according to the present example can achieve 90% or more purification of styrene gas exhaust gas with a heat exchange efficiency of 85% or more. In conventional methods using aluminum heat exchangers, it is possible to achieve an exhaust gas purification rate of 90% or more, but the heat exchange rate is limited to 50 to 60% even in continuous operation. Under the most excellent conditions of this example, both the styrene gas purification rate and thermal efficiency were 90% or more.

Furthermore, in this embodiment, alumina is used as the heat storage material, and because it has excellent corrosion resistance, it does not contain components that corrode metals (for example, acid gas, etc.) in the exhaust gas.
Even if it contains, it can withstand use.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, the heating body 10 is divided into left and right chambers, and is located between the catalyst 9 and the heat storage layer 6. With this structure, all of the installed catalysts can contribute to exhaust gas purification, and by installing the temperature control sensor of the heating element 10 in the communicating portion of both chambers, the temperature increase of the exhaust gas can be accurately controlled. The flow of exhaust gas is the same as in Example 1.

Table 2 shows the results of measuring the harmful component purification effect and thermal efficiency in this example.

[0020]

[Table 2]

[0021] The catalyst purification device of this example uses granular alumina (5 to 10 mm) as a heat storage body, as in Example 1.
5 liters of φ) were used. The catalyst uses 1 liter of honeycomb-shaped platinum catalyst, and each heating device has a max.
The temperature was controlled at 300°C using a kW sheathed heater. The exhaust gas contained 100 ppm of styrene gas, and the air flow rate was 500 liters/min. The purification rate of exhaust gas is expressed as the decomposition rate of styrene gas using a catalyst, and thermal efficiency is simply calculated as 30°C assuming that the exhaust gas is heated to 300°C.
It was calculated by comparing the difference between the outlet temperature and the inlet temperature with respect to the temperature raised to 0°C. The switching time refers to the time during which the exhaust gas continues to flow in one direction, and the exhaust gas does not flow for 10 seconds when the damper is switched.

As is clear from Table 2, the catalytic purification apparatus according to this example has a higher purification rate of styrene gas exhaust gas and lower heat exchange efficiency than that of Example 1. However, in this example, under the best conditions,
Both the styrene gas purification rate and thermal efficiency were over 90%.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, (b) shows a cross-sectional view taken along the line AB in (a), and (c) shows a cross-sectional view taken along the line CD in (a). The difference from the first embodiment is that, as is clear in (a), the structure of the damper portion where each chamber communicates with the outlet side flow path and the inlet side flow path has been changed, and the flow paths etc. have a simple structure. This is what is happening. The exhaust gas flows in the direction of each arrow. The efficiency of catalyst purification and heat exchange was similar to the first example.

[0025]

[Effects of the Invention] As described above, according to the present invention, the main body of the purification device is divided into two chambers each having a heat storage layer, and one open end is arranged alternately with the inlet side flow path and the outlet side flow path of the exhaust gas. It has a structure in which the heating device and the catalyst are installed in the closed end portion, which communicates with each other, and the exhaust gas introduced from the opening of one chamber is heated from the heat storage layer. After being supplied with energy and purified of harmful components by a heating device and a catalyst layer, heat is exchanged and cooled by a heat storage layer in the other chamber, and the mixture is discharged from the opening to the outlet side flow path. After a certain period of purification treatment, the damper is switched to cause the exhaust gas to flow in the opposite direction, so that the heat storage layer in each chamber performs the opposite heat exchange action. By repeating this process alternately, a catalytic purification device is realized which can minimize loss of thermal energy and efficiently purify harmful components in exhaust gas.

In addition, even when the flow of exhaust gas is intermittent, it exhibits sufficient heat exchange efficiency and ceramics with excellent corrosion resistance such as alumina can be used as a heat storage material, so there are no components in the exhaust gas that corrode metals. For example, it can withstand use even if it contains acidic gas.

[Brief explanation of the drawing]

FIG. 1 (a) shows the overall configuration of a catalyst purification device in a first embodiment of the present invention; (b) shows a cross section taken along A-B in (a); (c), (d);
) Shows the state where the flow of exhaust gas in (a) and (b) is reversed.

FIG. 2 (a) shows the overall configuration of a catalyst purification device in a second embodiment of the present invention; (b) shows a cross section taken along line A-B in (a); (c), (d);
) Shows the state where the flow of exhaust gas in (a) and (b) is reversed.

FIG. 3 (a) shows the overall configuration of a catalyst purification device in a third embodiment of the present invention; (b) shows a cross section taken along the line A-B in (a); (c) (a)
shows a cross section at the C-D section of

[Fig. 4] (a) Shows the configuration of a conventional catalyst purification device main body. (b) Shows the entire configuration of a conventional catalyst purification system including a heat exchanger.

[Explanation of symbols]

7　Catalytic purification device main body 6 Heat storage layer 9 Catalyst 10 Heating device

Claims (4)

[Claims] Claim 1: It has a main body divided into two chambers that are open at one end and closed at the other end and communicate with each other at that portion, and a heat storage layer is provided on the opening side of each chamber. An intermittent catalytic purification device characterized in that a catalyst and a heating device are respectively disposed on the sides, and the openings of each chamber communicate with an inlet flow path and an outlet flow path of exhaust gas through dampers. 2. The intermittent catalytic purification device according to claim 1, wherein a heating device is disposed in a communicating portion between the two chambers, and a catalyst is disposed between the heating device and the heat storage layer. 3. The intermittent catalytic purification device according to claim 1, wherein the catalyst is disposed in a communicating portion between the two chambers, and a heating device is disposed between the catalyst and the heat storage layer. [Claim 4] It has a main body divided into two chambers that are open at one end and closed at the other end and communicate with each other at that portion, and each of the two chambers is connected to one of opposite gas flow paths at the outlet or inlet. Exhaust gas containing malodorous components flows into one chamber from the gas flow path at the entrance, is heated by a heat storage body and heating device, is purified by a catalyst, and is cooled by a heat storage layer in the other chamber. The exhaust gas is discharged into the gas flow path at the outlet, and the flow of exhaust gas inside the purifier body is reversed by switching the damper installed at the opening of the main body, and the exhaust gas is discharged after undergoing heating, purification, and cooling processes. An intermittent catalytic purification method characterized by purifying harmful components in exhaust gas by repeating the process alternately.