JP2695666B2 - Reactor with catalyst pack - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a reactor equipped with a catalyst pack such as a denitration reactor.

[Prior Art] The arrangement of a catalyst pack and a suit blower in a conventional denitration reactor will be described with reference to FIG.

The denitration reactor 1 has a space where the suit blowers 10, 11, and 12 can be installed on the upstream side of each catalyst pack, and the catalyst pack 4 and the catalyst pack 5 are arranged in the flowing direction of the gas to be treated (indicated by arrows 2 and 3). And a catalyst pack 6 are spaced apart. FIG. 4 shows a case where the number of catalyst packs is three, but usually two to five catalyst packs are often used. Reference numerals 7, 8, and 9 denote support members for the catalyst packs 4, 5, and 6.

As shown in FIG. 5, each of the catalyst packs 4, 5, and 6 is provided with a plurality of cells 20 having a square cross section extending in the axial direction and having both ends opened and having the same cross section, and the catalyst is accommodated therein. The unit quantity of the catalyst element 21 is stored, the opening on one inlet side of the cell faces the gas flow, and the axis of the cell is arranged parallel to the gas flow direction.

Here, the purpose of installation of the conventional suit blower is that the cell 20 of each catalyst element (normally, the maximum element length is 1.000 m)
The dust adhering and accumulating on the wall of m) is to be separated, conveyed and removed by the penetrating force of the fluid medium of the suit blower.

Therefore, the length of the catalyst element in each cell is usually reduced because the adhered dust is removed by the penetrating force of the fluid medium.
The catalyst element is divided and accommodated in the catalyst pack so as not to exceed 1.000 mm, a space is provided between the catalyst packs in the gas flow direction, and a suit blower is provided in the space.

[Problems to be solved by the invention]

In the above-described conventional denitration reactor, the catalyst elements provided in each stage of the catalyst pack are arranged with a space provided between them, and in a denitration reactor capable of storing the same amount of catalyst, Inevitably, not only does the overall length of the reactor become longer, but also it is necessary to dispose a suit blower for each space. .

An object of the present invention is to solve the above problems and to provide a reactor having a compact and inexpensive catalyst pack.

[Means for solving the problem]

The present invention provides a catalyst comprising a catalyst element having a plurality of cells open at both ends and having a plurality of catalyst packs arranged in the gas flow direction with the axis of the catalyst element arranged in parallel to the gas flow direction. In a reactor equipped with a pack, the distance between the catalyst elements of adjacent catalyst packs is set to 40 times or less the diameter equivalent to the opening of the cell, and fluid is supplied to the cell opening on the gas inlet side upstream of the most upstream catalyst pack. A suit blower for ejecting the medium was provided.

[Action]

The clogging of the catalyst element is caused by the minute dust in the gas to be treated being disturbed by the turbulence of the gas and being attached to the catalyst element by collision due to the turbulence.

Here, as shown in FIG. 8, in the first stage catalyst element in the uppermost stream, gas such as exhaust gas flows from the upstream, but there is usually a drift in the gas and the gas flow becomes turbulent (Reynolds number). 2300 or more), and the dust contained in the gas has a large scattering motion, so that the dust adheres to the vicinity of the opening on the end face on the gas inlet side of the cell of the catalyst element and causes clogging.

On the other hand, the gas flow in each cell of the catalyst element is
Has a laminar flow due to the small cross section. Therefore, dust does not adhere to the inner surface of the cell.

Further, as shown in FIG. 8, the laminar flow of the gas flow remains for a certain distance even after leaving the cell 20 of the first-stage catalytic element. However, this laminar flow also transitions to turbulent flow again after flowing over a certain distance as shown in FIG.

As shown in FIG. 9, by installing the second-stage catalyst element at an interval of a distance L within a distance at which this laminar flow transitions to turbulent flow, catalyst clogging of the second-stage catalyst element is prevented. (The same applies to the third and subsequent steps).

Based on the above, the present inventor has found that the clogging of the catalyst element of the catalyst pack of a gas reactor containing small particulates such as exhaust gas from diesel engines and the like is mainly caused by the gas inlet end face of the cell of the catalyst element. It was confirmed by experiments that the particles were only generated on the side walls of the cells, and the deposits on the side wall surfaces of the cells were minute and had no practical problems.

Furthermore, if the distance L between the catalyst element at the preceding stage and the element at the subsequent stage is set to be 40 times or less the equivalent diameter of the opening of the cell of the catalyst element (diameter of a circle having the same area as the opening), It has been found by experiments that the gas flow exiting the cell of the element flows into the cell of the subsequent catalyst element while maintaining a laminar flow, and no clogging of the catalyst occurs.

In the present invention, based on the above findings, the interval between the catalyst elements of the catalyst packs adjacent to each other in the gas flow direction is set to 40 times or less the equivalent diameter of the cell opening of the catalyst element. This prevents the second and subsequent catalysts from being clogged.

Further, in the uppermost stream (first stage) catalyst element, dust adhering near the dust opening is removed by injecting a fluid medium from a suit blower into the opening of the cell on the gas inlet side. As described above, dust is prevented from adhering to the openings on the gas inlet side of the cells of the second and subsequent catalytic elements by setting the distance between the catalytic elements to 40 times or less the equivalent diameter of the cell openings. It is not necessary to provide a suit blower in the part. Accordingly, the length of the reactor is reduced.

〔Example〕

 A first embodiment of the present invention will be described with reference to FIG.

In this embodiment, the unit quantity of the above-described catalyst element having the structure shown in FIG. 5 is placed on the catalyst pack supporting member 9 of the denitration reactor 1 in which gas flows downward from above as indicated by arrows 2 and 3. The three catalyst packs 4 to 6 provided are stacked, and the space 17 between the catalyst element 14 of the catalyst pack 4 at the most upstream (uppermost stage) and the catalyst element 15 of the catalyst pack 5 at the second stage, and the catalyst element 15 and the most downstream The interval 17 between the catalyst elements 16 of the third-stage catalyst pack 6 was set to 40 times or less the equivalent diameter of the cell opening of the catalyst element. Further, two suit blowers 10 for injecting a fluid medium such as steam or compressed air toward the cell opening of the catalyst element 4 of the same pack are provided only on the upstream side of the catalyst pack 4 at the uppermost stream.

In the present embodiment, since the interval 17 between the adjacent catalyst elements 14, 15, 16 is set to be 40 times or less the equivalent opening diameter of the cell, as described in detail in the above-mentioned `` action '' section,
The second and third catalyst elements 15, 16 are prevented from being clogged. Further, in the uppermost catalyst element 14, dust adheres to the vicinity of the gas inlet of the cell due to gas drift and turbulence as described above, but the suit blower 10 is operated periodically or as needed. By doing so, the dust adhered by the fluid medium is peeled off and conveyed to the downstream side, whereby clogging of the catalyst element is prevented.

In addition, since the second and subsequent catalyst packs 5 and 6 are not provided with a suit blower, the length of the reactor 1 can be reduced.

In the second embodiment of the present invention shown in FIG. 2, three stages of catalyst packs 4, 5, and 6 are arranged in a reactor 1 in which gas flows upward from below as shown by arrows 2 and 3. In a third embodiment of the present invention shown in FIG. 3, a three-stage catalyst pack 4, 5, 6 is arranged in a reactor 1 in which gas flows laterally as shown by arrows 2, 3. Other configurations are the same as in the first embodiment.

Also in these second and third embodiments, only the flow direction of the gas is different, and the same operations and effects as those of the first embodiment can be obtained.

An experimental example according to the present invention will be described below. As shown in FIG. 6, a catalyst element having a structure similar to that shown in FIG.
Ducts 3 and 14 are provided so that the distance L can be changed.
0 and the exhaust gas is passed through the catalyst element 1 in the duct 30.
4 so as to flow toward the catalyst element 15, and a suit blower 1 so as to jet a jet toward the catalyst element 14 as shown in the drawing upstream of the catalyst element 14.
0 and 1 were arranged and operated intermittently. FIG. 7 shows an experimental result of the presence or absence of clogging of the second-stage catalyst element 15 when the equivalent diameter D of the cell opening and the catalyst element L are changed. As shown in FIG. 7, when L is set to 40D or less,
It was confirmed that clogging of the second-stage catalyst element 15 was prevented.

〔The invention's effect〕

 The present invention has the following effects.

(1) By setting the distance between the catalyst elements of the catalyst packs adjacent to each other in the gas flow direction to 40 times or less the equivalent diameter of the cell opening of the catalyst element, the catalyst elements in the second and subsequent stages in the gas flow direction can be used. Clogging can be prevented. Also, clogging of the uppermost catalyst element can be prevented by a suit blower on the upstream side of the element.

(2) The reactor can be made very compact because no useless space is required between the catalyst packs.

(3) The suit blower is installed only in the catalyst pack at the uppermost stream, so that the number of installed suit blowers can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a denitration reactor according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a denitration reactor according to a second embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view of a denitration reactor according to a third embodiment, FIG. 4 is a cross-sectional view of a denitration reactor having a conventional catalyst pack, FIG. 5 is a perspective view of a catalyst element, and FIG.
FIG. 7 is a cross-sectional view of a test apparatus according to the present invention, FIG. 7 is a graph showing test results by the test apparatus, and FIGS. 8 and 9 are explanatory views of gas flowing through cells of the catalyst element. 1 denitration reactor, 4,5,6 ... catalyst pack, 10 ... suit blower, 14,15,16 ... catalyst element, 17 ... catalyst element interval, 20 ... cell, 21 ... catalyst element .

Claims (1)

(57) [Claims] 1. A plurality of catalyst packs each comprising a catalyst element having a plurality of open cells at both ends and having the axis of the catalyst element arranged in parallel to the gas flow direction. In a reactor equipped with a catalyst pack, the distance between the catalyst elements of adjacent catalyst packs is 40 times or less the opening equivalent diameter of the cell, and the cell opening on the gas inlet side is located upstream of the most upstream catalyst pack. A reactor equipped with a catalyst pack, provided with a suit blower for injecting a fluid medium.