Method for cleaning a flue gas stream and flue gas cleaning system

Abstract

Method for cleaning a flue gas stream, in particular for cleaning flue gases produced during the combustion of heavy oil and / or diesel fuels, in a flue gas cleaning plant with at least one first reactor unit (5a-c, 35a-c, 65a-c) and a second reactor unit (5a-c, 35a-c, 65a-c), wherein in a pre-cleaning operation particles are substantially removed from the flue gas stream and in a final cleaning operation at least sulfur-containing components are substantially removed, wherein i. in the pre-cleaning operation the flue gas stream is fed from an engine (1, 31, 61) to the first reactor unit (5a-c, 35a-c, 65a-c) in which a pre-cleaning of the flue gas stream is carried out, and ii.In the final cleaning operation, the flue gas stream is transferred, after pre-cleaning, from the first reactor unit (5a-c, 35a-c, 65a-c) to the second reactor unit (5a-c, 35a-c, 65a-c), in which final cleaning of the flue gas stream is carried out, characterized in that at least a third reactor unit (5a-c, 35a-c, 65a-c) is provided with a sorption material (23a-c, 53a-c, 88a-c), wherein at least one reactor unit (5a-c, 35a-c, 65a-c) is in the pre-cleaning state, one reactor unit (5a-c, 35a-c, 65a-c) is in the final cleaning state and one reactor unit (5a-c, 35a-c, 65a-c) is in the standby state, so that the sorption material of the reactor unit It can be replaced while at rest.

Description

The invention relates to a method for cleaning a flue gas stream according to the preamble of claim 1 and a flue gas cleaning system according to the preamble of claim 8. Air pollution from ships and oil rigs has historically received less attention than, for example, from land-based industrial facilities. This is primarily due to the limited space required on ships. To reduce emissions of pollutants from ship combustion products into the air, Annex 6 was added to the International Convention for the Prevention of Pollution from Ships (MARPOL) in 1997. This annex specifically addresses air pollution from ships and entered into force on May 19, 2005. This directive, developed by the International Marine Organization, sets high standards for the quality of fuels used and for specific combustion systems. Furthermore, Annex 6 established specific North Sea SOx Emission Control Areas (SECAs). Large vessels such as tankers, luxury liners, and ferries almost exclusively use heavy fuel oil and / or diesel fuels, which produce exhaust gases with a high sulfur content during combustion. This high sulfur content, however, prevents the efficient afterburning of these exhaust gases by a catalytic converter. Sulfur-containing exhaust gases are known to be catalyst poisons, impairing the catalyst's function. The same applies to soot particles, which are produced in large quantities during the combustion of heavy fuel oil and diesel fuels on transport ships and oil rigs. Each ship has individual space requirements for its exhaust gas cleaning systems. Therefore, large-scale exhaust gas cleaning systems, as used in industrial plants, cannot simply be transferred to a ship. Relevant state of the art can be found in DE 10 2010 016 004 A1, in DE 40 02 462 A1 and in WO90 / 07973 A1 The invention addresses the problem of creating a method that enables the efficient and space-saving cleaning of flue gases produced during the combustion of heavy oil and / or diesel fuel. The invention solves this problem by means of a method with the features of claim 1 and a flue gas cleaning system with the features of claim 8. A substantial removal of a component is to be understood as a reduction of this component by more than 50 wt.%, preferably more than 90 wt.%, particularly preferably more than 95 wt.% compared to the initial composition. In this process, a flue gas stream is fed to the reactor unit during pre-cleaning operation, or a pre-cleaned flue gas stream is fed to it during final cleaning operation. Switching from residual cleaning mode to pre-cleaning mode results in more efficient use of the reactor unit. Furthermore, the individual reactor units of the flue gas cleaning system can be located in different areas of the ship. Since each reactor unit of a flue gas system can perform either a pre-cleaning step or a final cleaning step, the reactor units can be interchanged when several reactor units are arranged. The space saving is particularly advantageous for ships, drilling platforms and the like, since only limited space is available for a flue gas cleaning system; for example, reactor units can be mounted in different locations in the cargo hold of a ship. Advantageous embodiments of the invention can be found in the dependent claims. It is advantageous if the first reactor unit switches from residual cleaning mode to pre-cleaning mode after residual cleaning, depending on the consumption status of the sorbent material in a second reactor unit, and / or depending on the sulfur content and / or particle content of the flue gas stream. This allows for efficient use of the sorbent material, thereby increasing the individual operating time of the respective reactor unit. It is advantageous if, after the shutdown of the first reactor unit following the completion of the pre-cleaning operation, the sorption material and / or a reactor casing of the first reactor unit is replaced, so that the reactor unit can be switched on again in the final cleaning operation if necessary. For efficient and trouble-free operation of the flue gas system, it is advantageous if the flue gas flow supplied for pre-cleaning is controlled by the sulfur content and / or temperature of the flue gas. If the sulfur content is too low or the temperature is insufficient for effective desulfurization, the flue gas can also be released directly into the environment or routed to a denitrification plant. The gases discharged from the flue gas cleaning system comply with the requirements established by the SECA guidelines and the MARPOL Convention. The process can also be used on ship engines with turbochargers that generate a slight overpressure in the reactor. Additionally, the process according to the invention can be used for a full flow of exhaust gases leading away from the engine, as well as for a partial flow. Further applications include stationary agricultural machinery in which engines are operated with heavy fuel oil or diesel fuel. According to the invention, a flue gas cleaning system comprises at least a first and a second reactor unit. The first reactor unit includes at least a reactor housing, a flue gas inlet, a discharge for sulfur-free clean gas, and also a transfer line for pre-cleaned flue gas. This design allows the reactor unit to be operated modularly in both pre-cleaning and final cleaning modes. It can be exchanged as a module for similarly constructed reactor units. The sorption material can advantageously be used as a continuously or discontinuously flowing or as a non-flowing packed bed granulate, wherein the granule grains can have a diameter of 1-8mm. In desulfurization, a calcium carbonate-containing granulate is advantageously used as a dry sorption material, which forms gypsum upon deposition of, for example, sulfur trioxide. In desulfurization, a calcium hydroxide-containing granulate is advantageously used as a dry sorption material, which effectively neutralizes acidic gases such as HCl. The purification of flue gas from nitrogen oxides by dry sorption can be advantageously carried out using urea granules, whereby NOx gases are reduced to nitrogen. According to the invention, the flue gas cleaning system has at least three reactor units, of which at least one reactor unit is in the pre-cleaning state, one reactor unit is in the final cleaning state and one reactor unit is in the idle state, so that the sorption material of the reactor unit in the idle state can be replaced. It is further advantageous if the inlet, outlet and transfer of a reactor unit each have at least one control element, preferably a valve or flap, so that the operating state can be changed manually or automatically by simply blocking the gas flow of one of the aforementioned lines. For advantageous decoupling and subsequent removal of a reactor casing from the flue gas cleaning system, it is beneficial if a connecting element is arranged between the reactor casing and the control device. To facilitate the time-saving replacement of individual reactor casings with depleted sorption material for fresh sorption material, it is advantageous for the flue gas cleaning system to have several reactor units. Each reactor unit has a reactor casing, a flue gas inlet, a discharge for sulfur-free clean gas, and a transfer line for pre-cleaned flue gas. The regulation of the inflow and / or outflow of flue gas, and thus also of the gas pressure, can advantageously be achieved by a control element located on the flue gas side and / or the clean gas side. A control element located on the clean gas side is particularly preferred, as the risk of clogging by particles in the flue gas is relatively low at this point. The amount of flue gas in the flue gas cleaning system can be advantageously ensured via a measuring orifice to control the control element. The following drawings describe in more detail three embodiments of flue gas cleaning systems with which the inventive method is implemented. Figure 1 shows the circuit diagram of a first flue gas cleaning system according to the invention with three reactor units, Figure 2 shows the circuit diagram of a second embodiment of a flue gas cleaning system according to the invention, and Figure 3 shows the circuit diagram of a third embodiment of a flue gas cleaning system according to the invention. Fig. 1 shows a flue gas cleaning system for heavy oil and / or diesel fuel-powered engines, for example on ships, drilling platforms or larger agricultural machines, into which the flue gas is first expelled under overpressure from an engine 1 and introduced via a line 2. In this case, line 2 has three supply lines 4a-4c, each with a control device 3a-3c, for example a shut-off valve. The flue gas can be routed via the respective supply line 4a-4c to a reactor unit 5a-5c if it is in pre-cleaning mode. The first reactor unit 5a is described in detail below: The first reactor unit 5a has a reactor housing in which a sorption material 23a in the form of granules is arranged. Since the reactor unit 5a is preferably a packed-bed absorber, it has a feed line 15a and a discharge 9a for the sorption material 23a. To prevent the reactor unit 5a from emptying, it advantageously has a level sensor 7a and a control element 10a, preferably a flap, at the discharge 9a. The sorption material 23a is supplied from a storage container (not shown) via the supply line 15a and can be stored in a collection container (also not shown) after passing through the reactor unit 5a. The reactor unit 5a also has a transfer unit 11a, with a further control element 12a, e.g. a flap or a valve 12a, for transferring pre-cleaned flue gas from the first reactor unit 5a to a second reactor unit 5b, provided that the first reactor unit 5a is in the operating state of pre-cleaning. The transfer pipe 11a can be configured in various ways. In one exemplary configuration, the transfer pipe 11a is divided into two sections (not shown), the first of which branches off from an upper section of the respective reactor unit 5a-5c, and the second of which branches off from a lower section of the reactor unit 5a-5c. Advantageously, both sections of the transfer pipe are merged into a single pipe, with a control device (not shown), for example a three-way valve, located at the merging point. This allows, for example, the transfer of pre-cleaned flue gas from the upper section of the first reactor unit 5a to the lower section of the second reactor unit 5b. The first reactor unit 5a also has a discharge 13a, with a flap or a valve 14a, for the discharge of cleaned exhaust gas from the first reactor unit 5a and from the flue gas system, provided that the first reactor unit 5a is in the operating state of residual cleaning. In reactor unit 5a, intermediate shelves Z can be arranged such that the flow path of the gas to be purified is extended over a multiple of the width of reactor 5a. These intermediate shelves Z, for example steel plates, are spaced apart from each other in such a way that a transport path for the granules is possible. To monitor the reaction conditions within reactor unit 5a, the reactor unit has a temperature sensor 6a and a pressure sensor 8a. In this example, the flue gas cleaning system has three analogously constructed reactor units 5a-5c, which differ only in the state of the sorption material and are interconnected. Each of the three reactor units 5a-5c is designed to be operated either in pre-cleaning mode or in final cleaning mode, or to be ready for complete emptying and refilling, or to be ready for commissioning freshly filled. The connecting lines 11a-11c are advantageously connected to each other via a connecting line 16. Likewise, the connecting lines 13a-13c are advantageously connected to each other via a connecting line 17. To monitor the temperature of the flue gas which is introduced into the flue gas cleaning system and of the cleaned exhaust gas which exits the flue gas cleaning system (i.e. clean gas side), temperature sensors 18 and 21 are arranged on the flue gas side line 2 and the clean gas side connecting line 17. For pressure regulation within the flue gas cleaning system, the connecting line 17 has a further control element 20 in the form of a shut-off valve on the clean gas side. The connecting pipe 17 leads into a chimney 22, through which the cleaned exhaust gas can be released into the environment. The reaction products in the exhaust gas of a diesel engine depend on the engine design, engine power, and operating load. Since the reactivity of the sorption material 23a-c, particularly during the dry sorption of SOx-containing gases in residual cleaning operation, depends, among other things, on the temperature of the flue gas and the composition of the combusted heavy fuel oil in the ship's engine, a control element 21, arranged as a bypass on line 2, allows less pollutant-laden flue gases to be diverted directly to a catalyst (not shown) and from there to the chimney 22, depending on the composition of the flue gas. This can be individually adjusted by the user, for example, to save sorption material at low engine power. The same applies if complete combustion of the fuel by the engine is ensured. As an alternative to the previously mentioned embodiment in which the reactor units are designed as packed-bed absorbers, the reactor units can also be advantageously designed without inlets 15a-15c and outlets 9a-9c for sorption material. In this case, the flue gas would be passed over the sorption material without it being in countercurrent flow. With this particularly preferred embodiment, the space requirement of the flue gas cleaning system can be further reduced compared to the previously mentioned embodiment, since storage and collection tanks for sorption material can be omitted. In the case of the packed-bed absorbers described above, the storage and collection tanks can advantageously be smaller than in conventional reactors or reactor units. In a further advantageous embodiment, a heat exchanger is integrated into the flue gas cleaning system to efficiently utilize the thermal energy of the flue gas. Particularly preferably, the heat exchanger is arranged inside the reactor units, with the amount of heat varying depending on the engine type, so that the thermal energy can be used, for example, to liquefy the diesel fuel. The effectively recovered or utilized thermal energy ranges from 50 to 300 kW per MW of engine power. In the following, an exemplary embodiment of a flue gas cleaning process according to the invention is described in more detail. Flue gas produced by a combustion process is transferred via line 2 and supply line 4a to the first reactor unit 5a. The control valve 3a of the first reactor unit 5a is open, while all other control valves 3b, 3c and 21 of line 2 and supply lines 4b and 4c are closed. The first reactor unit is in pre-cleaning operation. This means: During the pre-cleaning process, particle filtration takes place. In this process, liquid and solid particles, such as soot particles and unburned hydrocarbons, are deposited on the surface of granular particles, which are then no longer available, or only to a limited extent, for the dry sorption of sulfur compounds. If reactor unit 5a-5c is in pre-cleaning mode, the control valve 12a of the transfer 11a is open and the control valve 14a of the discharge 13a is closed. The control valve 9a may also remain closed. This process involves the deposition or, in the case of porous materials, the absorption of solid and liquid components of the flue gas onto the granules of the sorption material. After the flue gas has passed through the sorption material 23a of the first reactor unit 5a and is therefore almost particle-free, it is transferred via the transfer line 11a of the first reactor unit 5a, the connecting line 16 and the transfer line 11b of the second reactor unit 5b into the second reactor unit 5b. The second reactor unit, 5b, is currently undergoing final cleaning. This means: During the final cleaning process, the flue gas is desulfurized. This involves the dry sorption of the sulfur-containing flue gas onto granules in the sorption material. The sorption material 23a-c is thus used in different ways in the respective operating stages of the pre-treatment and final treatment processes. Even when the sorption material can no longer be used for SOx dry sorption, it is still used particularly efficiently as a particle filter material. If the second reactor unit 5b is in residual cleaning mode, the control valve 12b of the transfer line 11b and the control valve 14b of the discharge line 13b are open. The control valve 3b of the feed line 4b is closed. Since the present embodiment is a packed-bed absorber, the control element 10b of the discharge 9b is also open. This defines a transport direction for the sorption material 23b in the reactor unit 5b. The pre-cleaned, nearly particle-free flue gas is preferably directed through the transfer 11b into the lower area of ​​the second reactor unit 5b, which is in final cleaning operation. In the variant of the packed-bed absorber shown in Fig. 1, the particle-free, sulfur-containing flue gas is passed through reactor unit 5b in countercurrent flow to the sorption material. The purified gas, which is at least approximately sulfur-free, is routed via the outlet 13b and the connecting line 17 to a chimney 22 and from there released into the environment. After completion of the pre-cleaning and final cleaning processes, a low-sulfur clean gas is obtained. However, this gas may still contain pollutants, which can be advantageously removed by additional post-cleaning units integrated into the flue gas cleaning system, i.e., downstream of the reactor units. In the present embodiment, a denitrification plant (DENOX plant) for flue gas denitrification can be arranged between the reactor units and the chimney. For the dry sorption of sulfur-containing flue gas, granules containing lime and / or hydrated lime are particularly preferred. During combustion, sulfur and sulfur-containing oxides (sulfur dioxide and sulfur trioxide) are formed, which are converted during transfer via calcium carbonate into calcium sulfates (gypsum), sulfites, and other sulfur-containing oxidation compounds (thiosulfates), etc. The sorption material can contain additional additives, such as calcium hydroxide, calcium oxide, magnesium oxide, silicon dioxide, iron oxide, and aluminum oxide. Calcium hydroxide, for example, provides additional neutralization during the sorption of acidic gas components like HCl and HF, in addition to sulfur oxides. Fe₂O₃ and Al₂O₃ can also enable catalytic afterburning of flue gas components. The sorption and neutralization can be further enhanced by the addition of hydrate components. The sorption material can, for example, also include limestone chippings, which in the present embodiment trickles from the storage reservoir vertically past the horizontally arranged intermediate floors Z to the reactor unit. Urea granules can be used to remove nitrogen oxides from flue gas by dry sorption. These granules are preferably urea-doped limestone grains, but other absorbent, heat-resistant materials doped with urea can also be used as carrier materials. Another additional or alternative possibility for the removal of nitrogen oxides is the addition of platinum / ceramic compounds to the sorption material. If urea granules are used as a component of the sorption material, a catalyst can be integrated into the components, for example in cascade blocks, cascade plates and / or collection hoods of the reactors according to the invention, in order to enable denitrification at the typical ship exhaust gas temperatures of approximately 150-200°C. The catalysis can also take place, for example, in a packed layer of catalyst granules. By integrating such a catalyst, the space required for a denitrification plant (DENOX plant) for flue gas denitrification on ships and also on land-based facilities can be advantageously saved. The sorption material is not limited to these additives and can be supplemented by further additives. Figure 1 also shows a third reactor unit 5c. This unit is not in an operating state. If this is the case, all control bodies 3c, 10c, 12c and 14c of the reactor unit 5c in question are closed. Each of the reactor units 5a-5c has, preferably between the control elements and the reactor casing, connecting means not shown, with which the reactor casing of a reactor unit can be decoupled from the flue gas cleaning system when the reactor unit is not in the pre-cleaning or residual cleaning state. When the sorption material 23c is loaded with solid and / or liquid particles after the respective reactor unit 5c has passed through both the residual cleaning state and the pre-cleaning state, the reactor housing, the storage container and the collection container, including the sorption material 23c, can be transported for refilling or, if necessary, replaced on site by a new reactor housing with storage container and collection container with fresh, unused sorption material. This offers particular advantages, for example, regarding the loading time of ships, where emptying the reactor in question is sometimes too time-consuming. At the same time, the sorption material can only be unloaded at the recycling station, thus effectively preventing the outgassing of unburned hydrocarbons that have accumulated on the sorption material. The discharge of granules from a packed-bed absorber reactor unit can be continuous or batchwise. A peeling drum increases the system's efficiency. The resulting reaction product can then be processed by a mill, preventing product buildup at the discharge flap at the bottom of the reactor. In a particularly preferred embodiment of the embodiment shown in Fig. 1, the reactor units 5a-5c have pressure-resistant reactor housings. Fig. 2 shows another particularly preferred embodiment of a flue gas cleaning system according to the invention. This plant also has three reactor units 35a-35c, which are identical in construction except for the state of the sorption material 53a-53c, but which, unlike Fig. 1, are not designed as packed bed absorbers and therefore do not have a feed line for sorption material and no outlet for spent sorption material. This design variant of a flue gas system has the additional advantage over the design variant of Fig. 1 that, due to the simplified construction, the system can be manufactured more cost-effectively and, by eliminating storage and collection containers for sorption material, also requires less space, which, among other things, increases the loading capacity of a ship accordingly. Furthermore, the sorption material is used even more efficiently, since all sorption material is used as particle filter material after switching the operating state of a reactor unit from residual cleaning operation to pre-cleaning operation, whereas in Fig. 1 only the sorption material that is not yet in the collection container is used. The following describes the cleaning of flue gas in the case where reactor unit 35a is in the pre-cleaning state and reactor unit 35b is in the final cleaning state. Unless otherwise described, the states of the individual control elements and lines of reactor units 35a-35c in Fig. 2 correspond to the states of the control elements and lines of reactor units 5a-5c in Fig. 1. In Fig. 2, flue gas is first introduced under pressure into a flue gas cleaning system via a line 32 by combustion of fuels in an engine 31. Line 32 has three supply lines 34a-34c, each with a control device 33a-33c. The flue gas is routed via supply line 34a to a first reactor unit 35a, which is in pre-cleaning mode. The first reactor unit 5a preferably has a pressure-resistant reactor housing in which a sorption material 53a is arranged immovably in the form of a packed bed. However, this sorption material 53a is no longer available, or only to a limited extent, for the dry sorption of sulfur-containing compounds, especially SOx compounds, but serves as a particle filter for solid and liquid components of the flue gas. The first reactor unit 35a has a transfer pipe 41a with a control element 42a. After particle filtration by the sorption material 53a, the pre-cleaned flue gas from an upper area, preferably above the packing of the first reactor unit 35a, is directed via the transfer pipe 41a, a connecting line 46 and a transfer pipe 42b connected thereto into a lower area of ​​a reactor unit 35b which is in a state of residual cleaning. In the second reactor unit 5a, the pre-cleaned flue gas is passed through the sorption material 53b for the dry sorption of sulfur compounds. Subsequently, the sulfur-free clean gas is discharged from reactor unit 35b through a duct 43b. The sulfur-free purified gas is then returned to the motor 1 via a connecting line 47, on which a measuring orifice 51 is arranged. The operation of the measuring orifice 51 is discussed in more detail elsewhere. According to the invention, a third reactor unit 35c is in a resting state, so that the sorption material 53c and / or the reactor housing can be replaced with the sorption material 53c if the sorption material 53c is consumed. In this process, a reactor casing of reaction unit 35c can be decoupled from the flue gas cleaning system, for example by loosening connecting elements not shown, and replaced by a new reactor casing with fresh sorption material 53c, while the other two reactor units 35a and 35b ensure continuous flue gas cleaning. Even very long cooling phases of the sorption material 53c can be bridged in this way without affecting the operation of the flue gas cleaning system. Likewise, maintenance work can be carried out on individual reactor units 35a-35c in the event of blockages or other malfunctions (while the plant is in operation). To increase the performance of the engine 31, it is advantageously coupled with a turbocharger 55, the operation of which is explained in more detail below. While the main flow of exhaust gas from engine 31 is fed to the exhaust gas cleaning system via line 32, a partial flow of the exhaust gases from engine 31 can be used to drive a turbocharger 55 via line 53. The combustion gases leave the turbocharger 55 via line 57. This turbocharger 55 draws in oxygen-containing ambient air via line 54, compresses it, and feeds the compressed air to the low-sulfur clean gas via another line 56 and a connecting line 47. The compressed air is fed into engine 31 together with the combustion gases. Due to the air compression, a larger quantity of air enters the cylinders during the intake stroke of engine 31 than, for example, in a naturally aspirated engine. This provides more oxygen for the combustion of a correspondingly larger quantity of fuel. This leads to an increase in the mean effective pressure and torque of the engine, thereby increasing the power output of engine 31. The measuring orifice 51 measures the flow rate on the clean gas side and is connected via a line 52 to a control element 50. This control of the control element 50 has, among other things, an influence on the performance of the motor 31. Fig. 3 shows another embodiment of a flue gas cleaning system according to the invention. This system differs from the system in Fig. 2 essentially in the arrangement of a control element 80 controlled by a measuring orifice 81 and in the supply of the clean gas / air mixture to a motor 61. A control element 80, for regulating the supply of flue gas to the flue gas cleaning system, is arranged on the flue gas side of a line 62, which carries flue gas from an engine 61 to the individual reactor units 65a-65c of the flue gas cleaning system. The control element 80 is controlled by a measuring orifice plate 81, which is connected to the control element 80 via a line 82. This measuring orifice plate 81 is arranged on the clean gas side of a connecting line 79, which carries low-sulfur clean gas to a turbocharger 85, and determines the flow rate of clean gas at this point. The control element 80 is controlled based on this determined flow rate. The control element 80 regulates the supply of flue gas to the flue gas cleaning system and thus also the pressure of the exhaust gases in the lines 62 and 83, which are arranged between the engine 61, the control element 80, and the turbocharger 85. While the main flow of exhaust gas from engine 61 is fed to the exhaust gas cleaning system via line 62, a partial flow of the ship's engine exhaust gases can be used to drive a turbocharger 85 via line 83. The combustion gases leave the turbocharger 85 via line 87. This turbocharger 85 draws in oxygen-containing ambient air via line 84. Line 84 leads into connecting line 79, which returns low-sulfur clean gas from the cleaning process to the turbocharger 85. The clean gas / air mixture is compressed by the turbocharger 85. Subsequently, the compressed clean gas / air mixture is fed to engine 61 via line 86 for fuel combustion. In all the aforementioned embodiments, the flue gas cleaning system always has three reactor units. However, the number of reactor units is not limited to three. According to the invention, each of the individual reactor units is either in pre-cleaning mode, in final cleaning mode, or in standby mode. Through a design modification of the described embodiments, exhaust noise can be reduced. Diesel engines, especially those on ships, are equipped with silencers on the exhaust side. These reduce the noise level depending on the size of the diesel engine. This reduction in exhaust noise can be achieved through absorption sound attenuation of the sorption material, whereby, among other things, the insulation of the reactor and / or the mass and particle size of the sorption material, for example, crushed stone, can be determined in such a way that the additional silencers can be eliminated or at least significantly reduced in size. This advantageously reduces the noise level to at least below 45 dB at 100 m. This, in turn, leads to a simplification of the packed bed system and a saving of space, which is a crucial criterion, especially on ships.

Claims

Method for cleaning a flue gas stream, in particular for cleaning flue gases produced during the combustion of heavy oil and / or diesel fuels, in a flue gas cleaning plant with at least one first reactor unit (5a-c, 35a-c, 65a-c) and a second reactor unit (5a-c, 35a-c, 65a-c), wherein in a pre-cleaning operation particles are substantially removed from the flue gas stream and in a final cleaning operation at least sulfur-containing components are substantially removed, wherein i. in the pre-cleaning operation the flue gas stream is fed from an engine (1, 31, 61) to the first reactor unit (5a-c, 35a-c, 65a-c) in which a pre-cleaning of the flue gas stream is carried out, and ii.In the final cleaning operation, the flue gas stream is transferred, after pre-cleaning, from the first reactor unit (5a-c, 35a-c, 65a-c) to the second reactor unit (5a-c, 35a-c, 65a-c), in which final cleaning of the flue gas stream is carried out, characterized in that at least a third reactor unit (5a-c, 35a-c, 65a-c) is provided with a sorption material (23a-c, 53a-c, 88a-c), wherein at least one reactor unit (5a-c, 35a-c, 65a-c) is in the pre-cleaning state, one reactor unit (5a-c, 35a-c, 65a-c) is in the final cleaning state and one reactor unit (5a-c, 35a-c, 65a-c) is in the standby state, so that the sorption material of the reactor unit It can be replaced while at rest. Method according to claim 1, characterized in that the cleaning of the flue gas stream is carried out as an adsorption and / or absorption of soot particles and / or dusts and a dry absorption of sulfur-containing components on a sorption material (23a-c, 53a-c, 88a-c). Method according to claim 1 or 2, characterized in that the first reactor unit (5a-c, 35a-c, 65a-c) is switched from residual cleaning operation to pre-cleaning operation. Method according to one of the preceding claims, characterized in that the second reactor unit (5a-c, 35a-c, 65a-c) transitions from residual cleaning operation to pre-cleaning operation depending on a consumption state of the sorption material (23a-c, 53a-c, 88a-c) of the first reactor unit (5a-c, 35a-c, 65a-c), and / or depending on a sulfur content and / or soot particle content of the flue gas stream after residual cleaning. Method according to claim 4, characterized in that the third reactor unit (5a-c, 35a-c, 65a-c) is switched on during the transition of the second reactor unit (5a-c, 35a-c, 65a-c) from the final cleaning operation to the pre-cleaning operation, in the final cleaning operation. Method according to one of the preceding claims, characterized in that the first reactor unit (5a-c, 35a-c, 65a-c) is switched off after the pre-cleaning operation has been completed, in order to replace the sorption material (23a-c, 53a-c, 88a-c) and / or a reactor casing of the first reactor unit (5a-c, 35a-c, 65a-c). Method according to one of the preceding claims, characterized in that the supply of the flue gas stream for pre-cleaning is dependent on the sulfur content. Flue gas cleaning system, comprising at least one first reactor unit (5a, 5b, 5c) and a second reactor unit (5a-c, 35a-c, 65a-c), wherein the first reactor unit (5a-c, 35a-c, 65a-c) comprises i. a reactor casing, ii. a supply line for flue gas in pre-cleaning operation (4a-c, 34a-c), and iii. a discharge for sulfur-free clean gas (13a-c, 43a-c, 73a-c) in final cleaning operation, characterized in that iv.The first reactor unit (5a-c, 35a-c, 65a-c) also has a transfer (11a-c, 41a-c, 71a-c) for pre-cleaned flue gas from the first reactor unit (5a-c, 35a-c, 65a-c) in pre-cleaning operation to a second reactor unit (5a-c, 35a-c, 65a-c) in final cleaning operation, and wherein the flue gas cleaning system has at least three reactor units (5a-c, 35a-c, 65a-c), of which at least one reactor unit (5a-c, 35a-c, 65a-c) is in pre-cleaning mode, one reactor unit (5a-c, 35a-c, 65a-c) is in final cleaning mode and one reactor unit (5a-c, 35a-c, 65a-c) is in standby mode. flue gas cleaning system, according to claim 8, characterized in that a sorption material (23a-c, 53a-c, 88a-c) is arranged in the reactor housing of the reactor unit (5a-c, 35a-c, 65a-c) as a packed bed granulate with granule grains of a mean diameter of 1-8mm. flue gas cleaning system according to claim 8 or 9, characterized in that the sorption material (23a-c, 53a-c, 88a-c) comprises calcium carbonate-containing granules and / or calcium hydroxide-containing granules and / or urea granules. flue gas cleaning system, according to one of the preceding claims, characterized in that the supply line (4a-c, 34a-c), discharge (13a-c, 43a-c, 73a-c) and the transfer (11a-c, 41a-c, 71a-c) each have at least one control element (3a-c, 12a-c, 14a-c, 33a-c, 42a-c, 44a-c, 63a-c, 72a-c, 74a-c), preferably a valve or a flap. flue gas cleaning system, according to one of the preceding claims, characterized in that a connecting means is arranged between the reactor housing and the control element (3a-c, 12a-c, 14a-c, 33a-c, 42a-c, 44a-c, 63a-c, 72a-c, 74a-c). A flue gas cleaning system according to one of the preceding claims, characterized in that the flue gas cleaning system comprises several reactor units (5a-c, 35a-c, 65a-c) each with i. a reactor casing, ii. a supply line for flue gas in pre-cleaning operation (4a-c, 34a-c), and iii. a discharge for sulfur-free clean gas (13a-c, 43a-c, 73a-c) in final cleaning operation, and iv. a transfer (11a-c, 41a-c, 71a-c) for pre-cleaned flue gas from the first reactor unit (5a-c, 35a-c, 65a-c) in pre-cleaning operation to a second reactor unit (5a-c, 35a-c, 65a-c) in final cleaning operation. flue gas cleaning system according to one of the preceding claims, characterized in that the flue gas cleaning system has a control element (21, 50, 80) on the flue gas side and / or clean gas side for controlling an inflow and / or outflow quantity of flue gas into and / or out of the flue gas cleaning system. flue gas cleaning system according to claim 14, characterized in that the flue gas cleaning system has a measuring orifice (51, 81) for controlling the control element (50, 80).

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