Method and Device Intended to Purify Sulphur Oxide Containing Exhaust Gas from Internal Combustion Engines by Means of a Multi-stage Adsorption Method

Abstract

A method and a device intended to purify pollutants from an exhaust gas flow of an internal combustion engine operated with sulphur containing fuel, in particular of a ship internal combustion engine operated with heavy fuel oil, are provided. Exhaust gas flow is in contact with a solid adsorption agent of the adsorber in a first step and binding in particular acid pollutants, which comprise sulphur dioxide and sulphur trioxide. The exhaust gas flow is then guided by a second stage of the adsorber realising fine purification of the exhaust gas flow. The adsorption agent of the second stage is used in the first stage as an adsorption agent.

Claims

1. A purification method of pollutants from an exhaust gas flow of an internal combustion engine operated with sulphur containing fuel, in particular a ship internal combustion engine operated with heavy fuel oil, characterised in that said exhaust gas flow being in contact with a solid adsorption agent (19) of the adsorber in a first stage (13), binding in particular acid pollutants, which comprise sulphur dioxide and sulphur trioxide, and where the exhaust gas flow is then guided by a second stage (15) of the adsorber realising fine purification of the exhaust gas flow and where the adsorption agent of the second stage (15) is used in the first stage (13) as adsorption agent.

2. The method according claim 1, wherein said adsorption agent (19) used is composed of granules containing calcium hydroxide and/or calcium carbonate, sodium carbonate and/or sodium hydrogen carbonate and/or magnesium oxide and/or magnesium hydroxide.

3. The method according to claim 1, wherein said solid absorbing agent (19) is available in the shape of granulated bulk material, having in particular a grain size between 1 mmm and 20 mm and preferably between 2 mm and 8 mm.

4. The method according to claim 1, wherein the solid adsorber (19) contains a carbon containing addition agent, in particular active charcoal and/or hearth-coke, in particular having a fraction from 0.1 per cent by weight to 50 per cent by weight, preferably from 1 per cent by weight to 35 per cent by weight.

5. The method according to claim 1, wherein the exhaust gas flow has a temperature between 150 C. and 450 C. when entering into the first stage of the adsorber.

6. The method according to claim 1, wherein said adsorption agent is guided continuously first via the second and then via the first stage of the adsorber.

7. The method according to claim 1, wherein said adsorption agent (19) is guided discontinuously first via the second and then via the first stage of the adsorber.

8. The method according to claim 7, wherein, during renewal of granules, an amount of unloaded granules is fed to the second stage and which correspond at least to the amount of granules of the first stage.

9. The method according to claim 1, wherein the same amounts of absorption agent are available in the first and the second stages.

10. The method according to claim 1, wherein the residence time of said granules in the absorber can be adjusted in the adsorber by means of the discharge amount and the discharge speed of the discharge members.

11. A purification device of pollutants coming from an exhaust gas flow of an internal combustion engine operated with a sulphur containing fuel, in particular with a ship internal combustion engine operated with heavy fuel oil, where said internal combustion engine has at least one exhaust pipe (10), which is flown through by said exhaust gas, comprising at least one shut-off valve (12a, 12b) available in said exhaust gas pipe (10), wherein exhaust gas cladding (14) is perforated in a first region (13) in flow direction (11) upstream said shut-off valve (12a), thereby forming a first adsorption stage, and a second region (15) in flow direction (11) downstream said shut-off valve (12b), thereby forming a second adsorption stage, wherein said perforated regions are covered by a continuous adsorption channel (17), wherein said adsorption channel (17) is covered by a flow channel (18), the interior cladding (20) of which limits said cladding (20) and is perforated such that, with the shut-off valve (12a, 12b) closed, said exhaust gas is guided outside through said perforation in the first region (13), passing by said adsorption channel (17) in said flow channel (18) and therefrom inside through said adsorption channel (17) and through said perforation in the second region (15), back into said exhaust gas pipe (10) in said flow direction (11) downstream said shut-off valve (12b).

12. The device according to claim 11, wherein said exhaust gas pipe (10) is not perforated in a shut-off valve (12a, 12b) zone (21) between the first and the second stage.

13. The device according to claim 11, wherein the exterior cladding (20) of the adsorption agent channel (17) is not perforated in the region corresponding to the non-perforated zone (21) of the exhaust gas pipe (10).

14. The device according to claim 11, wherein the first and the second exhaust gas pipe (10) regions are perforated alongside its circumference and in axial direction and that the adsorption agent channel (17) and the flow channel (18) surround both regions as a jacket.

15. The device according to claim 11, wherein both regions (13, 15) and said shut-off valve (12a, 12b) are arranged in a vertically extending portion of said exhaust gas pipe (10) and wherein said absorption agent channel (17) is Tillable from the top with an adsorption agent (19) and has at least one extraction member (23) intended for the used-up adsorption agent on its lower face such that the adsorption agent (19) is transported through said adsorption agent channel (17) due to gravity.

16. The device according to claim 11, wherein the first and second regions of the volumes of the adsorption channel (17) surrounding said exhaust gas pipe (10) fundamentally have the same size.

17. The device according to claim 11, wherein said extraction member is embodied as a rotary gate valve.

18. A device according to claim 11, wherein two shut-off valves (12a, 12b) which can be opened by forming a bypass, are provided in flow direction between the first and the second regions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Hereinafter, the invention will be explained in more detail by means of the schematic drawings. In these drawings:

[0033] FIG. 1 shows the longitudinal section of an exhaust gas pipe with an adsorber of the invention and

[0034] FIG. 2 shows the exhaust gas flow extending through the absorber of the invention.

DETAILED DESCRIPTION

[0035] The exhaust gas equipment shown in the drawing comprises an exhaust gas pipe 10 through which exhaust gas generated in the internal combustion equipment, not shown, flows in the main flow direction 11. Said exhaust gas pipe 10 extends at least in a portion vertically, for example through a hull, not shown, either.

[0036] Two shut-off valves 12a, b enabling shut-off of said exhaust gas pipe and arranged one after the other, are provided in said exhaust gas pipe 10 in flow direction 11. The cladding 14 of the exhaust gas pipe in a region 13 arranged in flow direction upstream the front shut-off valves 12a are embodied as perforated walls. The local cladding of the exhaust gas pipe 10 in a second region 15 arranged in flow direction 11 downstream the rear shut-off valves 12b is embodied as perforated cladding. Said perforations extend across a determined length of the exhaust gas pipe in flow direction 11 and around the entire total circumference of the exhaust gas pipe in the first and the second regions.

[0037] Both regions 13, 15 arranged one after the other in flow direction are surrounded by a jacket-shaped adsorption channel 17. Said adsorption channel 17 is in turn surrounded by a flow channel 18 having an annular cross section. In detail, said arrangement is embodied such that said adsorption channel 17 is permeable from the top to the bottom and filled with a granule-shaped adsorption agent 19. Said cladding 20 between the adsorption channel 17 and said exterior flow channel 18 is perforated in the regions extending alongside the circumference and facing the first and the second regions 13, 15. The claddings in the zone 21 wherein the shut-off valves 12a, b are arranged, are not perforated.

[0038] This arrangement provides a two-stage adsorber by simple means. Exhaust gas flows through said exhaust gas pipe 10 and is guided through said adsorption channel 17, said shut-off valves 12a, b being closed. Said adsorption agent is flown through transversally relative to the flow direction. Then, the exhaust gas arrives through the perforation in the exterior cladding 20 of said adsorption channel 17 into said flow channel 18 and flows through perforation arranged further downstream in flow direction 11, passing trough said fresh adsorption agent 19 arranged further upstream, back into the exhaust gas pipe in flow direction downstream the rear shut-off valve 12b. Thus, the first region 13 upstream the first shut-off valve 12a forms a first adsorption stage while the second region 15 downstream the second shut-off valve 12b forms a second adsorption stage.

[0039] Said adsorption agent is fed in said adsorption channel 17 having an annular cross section via feed openings 22 at the upper end of the latter. Due to gravity, it migrates downwards and is removed from the adsorption channel 17 at the lower end via discharge members 23 which can be embodied as rotary gate valves. In the upper region, directly upstream said feed opening 22, said adsorption channel 17 cannot be perforated alongside the circumference and hence be embodied in a closed manner in order to prevent any flow through the feed-in region of exhaust gas.

[0040] The hole size of the perforated portions of the corresponding claddings 14, 20 is dimensioned such that said granule-shaped adsorption agent 19 is safely maintained in the adsorption channel. For example, a hole size from 1.0 mm to 3.0 mm can be provided.

[0041] Hence, said adsorption agent 19 continuously or discontinuously migrates through said adsorption channel from the top to the bottom, while said exhaust gas flows through said adsorption agent 19, in a first step, from the bottom in the first region 13 and then in the upper, second region 15. This enables to reach a two-stage embodiment of the adsorber, where exhaust gas pre-purification takes place in the first stage 13 arranged in flow direction and exhaust gas fine purification takes place in the second region 15, downstream in flow direction. Such arrangement is extremely space-saving and can be integrated into ship structures, even later on.

[0042] For example, filling of the adsorber with said adsorption agent can be carried out by means of a pneumatic conveyor device, not shown, also enabling exhaustion of said absorber.

[0043] Altogether, this results into the exhaust gas flow pattern schematically shown in FIG. 2. In the event of a too important pressure rise in the adsorber channel 17, said shut-off valves 12a, b can be opened partially or totally. Then, said exhaust gas is dispensed into the environment following no or partial purification only. Depending on the fuel type used, said shut-off valves 12a, b can also be opened or closed. Such tasks can be realised simply and readily by the staff on board and can be adapted to the respective fuel type used.

[0044] Due to the two-stage method, the granule-shaped adsorption agent is almost entirely loaded with pollutants. To this end, fresh and unloaded adsorption agent is always available for said fine purification such that the desired emission guide values can be complied with. Only saturated adsorption agent is exhausted at the adsorption channel 17 exit, thereby resulting into economical consumption. Therefore, adsorption agent quantities to be taken along with can be kept to a minimum.