CONTACTING DEVIE FOR GAS AND SOLID PARTICLES

Abstract: Contacting device for gas and solid particles comprising a housing having an inlet space and an outlet space and at least one contacting element (7) arranged between the inlet space and the outlet space. The contacting element (7) comprises a first wall (11), a second wall (12) parallel to the first wall (11), and a permeable corrugated sheet (13) mounted on the side of the first wall (11) facing the second wall (12). A plurality of channels (17) connecting the inlet space to the outlet space are formed between the first wall (11) and the permeable corrugated sheet (13). A plurality of spacers (15) are arranged between the second wall (12) and the permeable corrugated sheet (13).

Description: The invention relates to a contacting device for gas and solid particles comprising a housing containing an inlet space, an outlet space and at least one contacting element. U.S.A. patent specification No. 3 873 287 discloses a contacting device containing at least one contacting element, and an inlet space and an outlet space arranged at opposite ends of the contacting element(s), wherein each contacting element comprises a first wall, a second wall parallel to the first wall. In the known device gas passages are defined between adjacent first and second walls and the particle space is outside the gas passages. Alternatively the gas passages are closed at opposite ends to force the gas to flow during normal operation through the particle spaces. During normal operation gas flows in a direction which is substantially perpendicular to the direction in which solid particles can be removed. It is an object of the present invention to maintain the feature that during normal operation gas flows through the contacting device in a direction which is substantially perpendicular to the direction in which solid particles can be removed and to provide a more compact device. It is a further object of the invention to provide a contacting device which has a lower resistance to gas flow. To this end the contacting device for gas and solid particles according to the invention is characterized in that the contacting device further includes a permeable corrugated sheet mounted on the side of the first wall facing the second wall so that channels are defined which extend between the inlet space and the outlet space, and a plurality of parallel spacers mounted between the second wall and the permeable corrugated sheet which are mounted at an angle of between 60° and 120° to the channels so that particle spaces are defined between the permeable corrugated sheet, the second wall and the parallel spacers. Reference is made to U.S.A. patent specification No. 4 028 275 which publication discloses a contacting device for gas and solid particles comprising a housing containing at least one contacting element, and an inlet space and an outlet space arranged at opposite ends of the contacting element(s). In the known device the contacting element(s) is (are) solid catalyst elements. These catalyst elements are difficult to replace when poisoned. During normal operation, the space between the second wall and the permeable corrugated sheet is filled with solid particles. The permeable corrugated sheet increases the surface between the channels and the space filled with solid particles. This enables a larger quantity of gas to move between the channels and the space filled with solid particles than in the known contacting device. A contacting device of this type is particularly suitable for gas treatment processes in which a low pressure drop is desirable or in which the gas being treated contains dust. Suitable gas treatment processes for which the contacting device can be used are the removal of nitrogen oxides and/or sulphur dioxide from flue gas, the cleaning of exhaust gas from internal combustion engines or the catalytic oxidation of hydrogen sulphide. Other processes for which the contacting device can be suitably employed are the catalytic conversion of synthesis gas, a gas mixture containing hydrogen and carbon monoxide, to liquefied hydrocarbons or alkanols such as methanol, the production of ethylene oxide, the catalytic conversion of hydrogen sulphide and sulphur dioxide to elemental sulphur according to the Claus process, or the catalytic reduction of sulphur dioxide in the presence of a reducing gas. The invention will now, by way of example, be discussed in more detail with reference to the drawings, in which Figure I shows schematically a vertical longitudinal section of the contacting device according to the invention; Figure 2 shows schematically section II-II of Figure 1, drawn on a larger scale than that of Figure 1; and Figure 3 shows schematically section III-III of Figure 2. The contacting device 1 for gas and particles comprises a housing 3 containing an inlet space 5 with an inlet 6, a contacting element 7, a contacting element 8 (see Figures 2 and 3) and an outlet space 9 with an outlet 10. The contacting element 7 comprises a first wall in the form of an impermeable separating plate 11 (see Figures 2 and 3), a second wall parallel to the first wall in the form of an impermeable separating plate 12, and a permeable corrugated sheet 13 mounted on the side of the first wall, separating plate 11, facing the second wall, separating plate 12. The contacting element 8 comprises a first wall in the form of an impermeable separating plate 12, a second wall, parallel to the first wall in the form of an impermeable separating plate 14, and a permeable corrugated sheet 13′ mounted on the side of the first wall, separating plate 12, facing the second wall, separating plate 14. A plurality of mutually parallel channels 17 are defined between the first wall of contacting element 7, separating plate 11, and the permeable corrugated sheet 13 mounted thereupon, and a plurality of mutually parallel channels 17′ are defined between the first wall of contacting element 8, separating plate 12, and the permeable corrugated sheet 13′ mounted therupon. The channels 17 and 17′ connect the inlet space 5 to the outlet space 9. The contacting element 7 further comprises a plurality of spacers in the form of parallel baffle plates 15 mounted perpendicularly to the channels 17. The baffle plates 15 are mounted between the second wall, the separating plate 12, and the tops of the permeable corrugated sheet 13. The contacting element 8 also comprises a plurality of spacers in the form of parallel baffle plates 15′ mounted perpendicular to the channels 17′ and between the second wall, the separating plate 14, and the tops of the permeable corrugated sheet 13′. The housing 3 of the contacting device 1 further comprises an upper wall 21 and a lower wall 23 which can be detachably mounted. In the contacting element 7, particle spaces 19 are defined between the separating plate 12, the permeable corrugated sheet 13 and baffle plates 15. In the contacting element 8, particle spaces 19′ are defined between a separating plate 14, a permeable corrugated sheet 13′ and baffle plates 15′. The height of the spacers is large enough for the particles to be able to move through the particle spaces 19 and 19′. During normal operation of the contacting device 1, the particle spaces 19 and 19′ are filled with solid particles. These solid particles are catalyst particles for a process in which compounds in the gas mixture being treated are catalytically converted, or adsorbing particles if compounds such as sulphur dioxide are removed from the gas mixture by adsorption. The gas mixture to be treated is introduced through inlet 6 into the inlet space 5 and flows through the channels 17 and 17′ to the outlet space 9. The treated gas leaves the contacting device 1 via outlet 10. Gas moves through the permeable corrugated sheets 13 and 13′ between the channels 17 and 17′ and the spaces 19 and 19′, in which spaces the gas comes into contact with the solid particles present therein. The treatment of the gas takes place in the particle spaces 19 and 19′. The permeable corrugated sheets 13 and 13′ give the channels 17 and 17′ a large surface through which gas can move between the channels 17 and 17′ and the particle spaces 19 and 19′. The cross sectional area of a channel is suitably between 0.1 and 5 cm². For a dirty gas containing many particles, for example soot, a suitable surface area is between 2 and 5 cm², while for a cleaner gas the surface area is less than 2 cm². The number of channels is preferably chosen such that the gas velocity in the channels is between 1 and 100 m/s. Very suitable velocities are between 3 and 20 m/s, at which velocities no particles will be deposited on the walls of the channels 17 and 17′. In a suitable embodiment of a contacting element, the distance between the first wall and the second wall is between 1.1 and 5 times the corrugation height of the permeable corrugated sheet. The drawings show a contacting device with two contacting elements. Depending on the application, the contacting device may be provided with one contacting element or more than two contacting elements. Figure 1 shows a contacting device in which the angle between the baffle plates 15 and the channels 17 is 90°. This angle suitably lies between 60° and 120°. If the angle between the channels through which the gas being treated flows and the baffle plates is chosen such that some spaces filled with particles extend from the inlet space to the outlet space, a part of these spaces can be kept empty so that gas can flow through them too. The contacting device shown in Figures 2 and 3 comprises contacting elements in which the baffle plates are mounted between the second wall and the tops of the permeable corrugated sheet. In an alternative embodiment the baffle plates can also extend to the valleys of the permeable corrugated sheets. Separating plates 12 and baffle plates 15 and 15′ can be permeably constructed so that the gas mixture that can flow through the channels 17 and 17′ can also move through the separating plates 12 and the baffle plates 15 and 15′. Permeable corrugated sheets, permeable separating plates and permeable baffle plates can be made of any suitable material, for example ceramic fibres, natural fibres, synthetic fibres, glass fibre or metal gauze whose mesh size is smaller than the size of the solid particles. If the separating plates 12 are made of non-rigid material, such as metal gauze, reinforcing means must be attached such that the contacting elements 7 and 8 are sufficiently strong and stiff. The particle spaces 19 and 19′ may be filled by, after detaching the upper wall 21, introducing solid particles into the particle spaces 19 and 19′. After filling, the upper wall 21 is replaced. After use, the solid particles are removed from the particle spaces 19 and 19′ by detaching the lower wall 23. If the spacers are perpendicular to the channels, the space to be filled with solid particles can be filled with solid particles in a direction perpendicular to the direction in which the gas flows through the channels. That is why the contacting device according to the invention is suitable for replacing the solid particles either intermittently or continuously, without having to shut down the contacting device. By replacing the upper wall 21 by a particle feed device (not shown) and the lower wall 23 by a particle discharge device (not shown), the solid particles can be fed continuously or intermittently through the particle spaces 19 and 19′. In order to renew the solid particles during normal operation, new solid particles can be added either intermittently or continuously and used solid particles discharged. Figure 1 shows a contacting device in which the channels 17 are straight. A compact contacting device can be obtained with channels which are at least partly curved, for example channels which are zigzag-shaped. Figure 2 shows an embodiment of the invention in which the corrugated sheets 13 and 13′ have an undulatory section, but the section can also be triangular, semicircular, trapezoidal or square. If components of the gas react endothermically or exothermically during the contact with the solid particles, the contacting device can be provided with means for adding or removing heat, located in the particle spaces. In a suitable embodiment, these means comprise channels (not shown) mounted on the side of the second wall facing the first wall. During normal operation, a suitable heat transport medium, such as steam, flows through these channels. The contacting device can suitably be used for treating exhaust gas from an internal combustion engine, for example as used in a motor vehicle.

Claims: Contacting device (1) for gas and solid particles comprising a housing (3) containing at least one contacting element (7), and an inlet space (5) and an outlet space (9) arranged at opposite ends of the contacting element(s) (7), wherein each contacting element (7) comprises a first wall (11), a second wall (12) parallel to the first wall (11), characterized in that the contacting device further includes a permeable corrugated sheet (13) mounted on the side of the first wall (11) facing the second wall (12) so that channels (17) are defined which extend between the inlet space (5) and the outlet space (9), and a plurality of parallel spacers (15) mounted between the second wall (12) and the permeable corrugated sheet (13) which are mounted at an angle of between 60° and 120° to the channels (17) so that particle spaces are defined between the permeable corrugated sheet (13), the second wall (12) and the parallel spacers (15). Contacting device as claimed in claim 1, characterized in that the cross-sectional area of a channel (17) is between 0.1 and 5 cm². Contacting device as claimed in claim 2, characterized in that the cross-sectional area of a channel (17) is less than 2 cm². Contacting device as claimed in any one of the claims 1-3, characterized in that the corrugations of the permeable corrugated sheet (13) are triangular, semicircular or trapezoidal. Contacting device as claimed in any one of the claims 1-4, characterized in that the angle of a spacer (15) to the channels (17) is 90°. Contacting device as claimed in any one of the claims 1-5, characterized in that a contacting element is provided with a permeable first wall (11) and/or a permeable second wall (12). Contacting device as claimed in any one of the claims 1-6, characterized in that the distance between the first wall (11) and the second wall (12) lies between 1.1 and 5 times the corrugation height of the permeable corrugated sheet (13). Contacting device as claimed in any one of the claims 1-7, characterized in that the housing (3) is provided with a particle feed device and a particle discharge device.

Inventors: GROENEVELD, MICHIEL JAN, ZUIDEVELD, PIETER LAMMERT
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1988
Main classification: B01D53
IPC codes: B01D53, F01N3, B01J8