KR102343017B1 - Method and equipment for wet desulfurization of exhaust gas of marine engine - Google Patents

Abstract

According to the method, the gas 1 to be desulfurized is conveyed into the scrubber 100 via a vertical chimney 200 open substantially at the center of the bottom face 101 of the scrubber. A gas flows upwardly inside the scrubber into contact with the first scrubbing liquid 3 and the second scrubbing liquid 4 intended to capture the sulfur dioxide contained therein. The gas is continuously passed through the scrubber so that the velocity profile of the gas is as flat as possible in the scrubber, a rotating device 400 passing the gas 1 and rotating the gas in the scrubber 100 of the gas a protective device 300 preventing the entry of liquid into the downstream outlet 201 of the chimney while maintaining flow, - from the central region of the scrubber 100 through which the geometrical central axis Z100 of the scrubber passes, the circumferential wall 102 of the scrubber a jetting device 500 for jetting a first scrubbing liquid 3 in the form of at least one pair of liquid curtains with Dispensing a second scrubbing liquid 4 in the form of a lane extending from the spraying device of the scrubber to the dispensing device and falling downward in a free space V100 in which the gas 1 freely flows. a distributor 601 of at least one stage, which is located at the same height and is distributed over the cross-section of the scrubber with respect to said height, dispensing the respective fractions of the corresponding lanes. includes

Description

Method and equipment for wet desulfurization of exhaust gas of marine engine

The present invention relates to a method and equipment for wet desulphurization of exhaust gases of marine engines.

Most ships, whether passenger ships or other ships, use fuel oil as fuel for diesel engines. This fuel oil contains up to 5% by weight of sulfur, mostly from 0.5 to 3.5% by weight. During the combustion process of the engine, this sulfur is converted to _{sulfur dioxide (SO 2 ).} As a result, the exhaust gas of this engine is acidic.

Maritime regulations in force in certain areas require that emissions from ship stacks be limited to the equivalent of 0.1% by weight sulfur in fuel oil. In practice, the emission limit values depend on the navigation area. Sulfur dioxide emissions near shore or in ports should be lower than in the open sea. It should be noted that even within ports, cruise ships have to keep their engines running to meet onboard electricity demand, potentially emitting sulfur dioxide. Therefore, to comply with regulations, ships must be equipped with means to reduce sulfur dioxide emissions and their fumes before they are released into the atmosphere. Several solutions can be considered.

It is possible to reduce the sulfur content of the fuel oil used or to use liquefied gas, which immediately reduces sulfur dioxide emissions. However, fuel oils with very low sulfur or liquefied gas content are expensive, so this method is not very economical.

Another approach is to use a wet scrubber in which a neutralizing reagent such as sodium hydroxide is dispersed. However, the flow rate of sulfur dioxide to be treated can reach a maximum of 500 kg/h per scrubber in the case of a large passenger ship, thus increasing the amount of sodium hydroxide to be supplied. Apart from the price of sodium dioxide, it is necessary to provide its storage, and it is necessary to take into account its very corrosive and dangerous properties.

Accordingly, the exhaust gas is mainly scrubbed with seawater. This technique is performed by scrubbers that use the natural alkalinity of seawater to neutralize sulfur dioxide, especially in power plants located next to the sea. Actually, there are two techniques.

The first technique is based on implementing a scrubber using a liner. This liner is composed of a ring or an inner, and has a structured or introduced mass into the scrubber top. That is, the liner has a structurally repeating pattern within the space. These liners are very good in terms of transport efficiency, ie their ability to trap the sulfur dioxide introduced into the volume used in the scrubber. However, two limitations should be considered. On the one hand, the pressure loss by the liner can be significant, and if the scrubber has to be installed downstream of the diesel engine, a fan must be used to overcome this pressure loss, resulting in energy and additional investment costs. On the other hand, the gas of a diesel engine is very hot, and despite the presence of a cooling device, it is expected that, after a malfunction occurs, very hot uncooled gas, for example exceeding 200° C., flows into the scrubber. Bypass is not always possible, and at least the scrubber and its liner must be able to withstand dry operation, and therefore the components must be able to withstand temperatures in excess of 200°C. This requires choosing a material that can withstand the temperature for the scrubber and liner. Therefore, for a scrubber installed on a ship, the chloride-rich, acidic and reducing marine environment is very corrosive, which significantly affects the cost of the liner.

A second technique, which uses seawater to reduce sulfur oxides in the gas, is widely used in power plants that produce energy on land. This second technique uses an empty scrubber where seawater is dispersed. This dispersion may be carried out in the form of droplets falling on the central region of the scrubber as taught in FR 1,231,173 and very schematically shown in FIG. 1 or in the form of a liquid curtain as very schematically shown in FIG. 2 . can

In this situation as can be seen from FIG. 1 , the gas F to be desulfurized is introduced to the bottom of the scrubber V through the chimney C centered on the bottom of the scrubber. In the central region of the head of the scrubber V, the nozzle moves the scrubbing liquid L provided to capture the sulfur dioxide present in the gas F counter-currently to the gas F circulating upwardly within the scrubber downward. Disperse in the form of falling droplets.

In this situation as can be seen from FIG. 2 , the gas F to be desulfurized is also introduced to the bottom of the scrubber V through the chimney C centered on the bottom of the scrubber. In the center of the scrubber V, the injector P serves to capture the sulfur dioxide present in the gas F in the form of a curtain from the region of the geometric central axis ZC of the scrubber V towards the main wall of said scrubber V. spray the scrubbing liquid.

Both of the solutions of Figure 1 and Figure 2 have advantages. They are simple, and since the scrubber V is empty and the gas F circulates freely, the pressure loss is low compared to solutions using a liner inside the scrubber. In addition, since the conveying capacity is lower than that of a scrubber using a liner, it is economical even if the height of the scrubber V is higher. Finally, since the scrubber V is essentially empty, there is no need to worry about its contamination as well as the components of the liner, particularly their ability to withstand corrosion and temperature. However, the low pressure loss, which is the main advantage from an operation point of view, makes the distribution of the gas F inside the scrubber V a problem. Indeed, in the case of the installation of Fig. 1, due to any instability due to the movement of the vessel, for example a small distortion of the distribution of the scrubbing liquid due to occlusion of the nozzle D, or even an instability within the meaning of the chaotic theory. , as schematically shown in Figure 1, the gas F to be treated is concentrated on one side of the scrubber, and the scrubbing liquid is offset to the other side of the scrubber, so the gas F in the scrubber V has asymmetric and unbalanced velocity profiles. , which is not necessarily stable with time, for example, a scale effect may appear in the process of external movement of the scrubber V. In the case of the facility of FIG. 2 , the gas F to be purified is gradually moved away from the central axis ZV by the transfer of a large amount of scrubbing liquid L towards the gas F, schematically shown in FIG. As it is concentrated on the circumferential wall of the scrubber V as shown, the velocity profile of the gas F undergoes distortion causing inhomogeneity. In both cases, despite the introduction of gas at the center of the bottom surface of the scrubber V, the ratio of liquid to gas, that is, a certain amount in the scrubber V, due to the inhomogeneity of the velocity profile of the gas F inside the scrubber V The ratio of the amount of scrubbing liquid and the amount of gas present at the location of F becomes inhomogeneous within the scrubber and causes a significant loss of gas (F) desulfurization efficiency.

US 2016/0016109 in relation to the problem described so far proposes a method and installation for the desulfurization of exhaust gases of marine engines, which can be considered to be the closest to the method and installation claimed herein. In US 2016/0016109, exhaust gas emitted by a marine engine is introduced into a scrubber through a vertical chimney, and this gas is circulated upwardly in the scrubber. Inside the scrubber, the gas coming out of the chimney passes through a first biasing member that protects the inlet of the chimney from liquid ingress, a first water jet for spraying water downward, a second water jet for jetting water upward, and a passage cross-section. The tightening is in succession with a constriction member, a second biasing member, a third water jet for spraying water downwards, and a condenser. The first, second and third injectors are all of the same type. The constriction member separates the interior of the scrubber into two chambers: a lower chamber in which the first biasing member and the first and second injectors are disposed, and an upper chamber in which the second biasing member and the third injector and the condenser are disposed. The constriction member tends to refocus the gas leaving the lower chamber and entering the upper chamber, but all of the first, second and third injectors are located on the geometrical central axis of the scrubber, the first, second and The circulation of gas in each of the two chambers is exposed to the risk of instability described above as the water jetted by the third injector tends to offset the circulation of gas with respect to the scrubber's main wall. In addition, the presence of the constriction member inevitably causes a significant pressure loss, and the water sprayed into the upper chamber and accumulated in the constriction member must be recovered through a dedicated extraction device. As a result, the desulfurization effect is changed.

In applications other than the desulfurization of exhaust gases, US Pat. No. 4,375,976 proposes a method and apparatus for removing dust from a gas stream, in particular an air stream. The gas stream for dust removal is first fed into a cyclone separator, at the top of which the gas stream is refocused and introduced vertically into a tube protruding from the base of the scrubber. In the interior of the scrubber, the gas flow circulates upwardly and continuously encounters a protective cone, a water jet, a water jet nozzle and a filter. The protective cone, sprayer and spray nozzle are aligned along the geometrical central axis of the scrubber. The injector P produces a jet having a low water density, substantially similar to a mist, and which is jetted horizontally from the central axis of the scrubber, the jet aimed at wetting the solid particles in the rising gas stream. . The sprayer also sprays water in an upward-facing cone to keep the underside of the filter wet. The dispensing nozzle creates a downwardly directed cone of water jet to wet the solid particles in the gas stream. These installations are content to trap solid particles suspended by the gas stream, and there is no effort to desulfurize the exhaust gases emitted by marine engines.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a scrubber apparatus which solves the above-mentioned drawbacks of exhaust gas desulfurization based on a smart and inexpensive embodiment.

To this end, the present invention relates to a method for wet desulfurization of exhaust gas of a marine engine, wherein a gas to be desulfurized is drawn into a scrubber through a vertical chimney projecting substantially from the center of a bottom surface of the scrubber, and the gas is circulated upwardly in the scrubber and is disposed in contact with a first scrubbing liquid and a second scrubbing liquid provided to capture sulfur dioxide contained in the gas, the gas being in the scrubber,
- A rotating device that passes the gas while rotating it in the scrubber,
- a protective device that prevents the introduction of liquid into the downstream inlet of the chimney while maintaining the circulation of the gas;
- an ejection device for ejecting a first scrubbing liquid in the form of at least a pair of liquid curtains from a central region of the scrubber through which the geometrical central axis of the scrubber passes to the circumferential wall of the scrubber, - each pair of liquid curtains in the same horizontal plane associated with the pair. jetted from the jetting device on both sides -, then
- continuously encountering a dispensing device for dispensing a second scrubbing liquid in the form of a rain extending from the jetting device to the dispensing device and falling downward in the free space of the scrubber in which the gas is freely circulated, said dispensing The apparatus comprises a dispenser of at least one stage located flush, each dispensing over a cross section of said scrubber relative to a height, and dispensing a corresponding fraction of said lane, respectively.

The present invention also relates to an installation for wet desulfurization of exhaust gases of ships, said installation comprising:
- a scrubber in a bottom surface from which a vertical chimney for the suction of gas in the scrubber protrudes substantially from the center;
- a rotating device suitable for passing the gas from the chimney to rotate the gas in the scrubber;
- protective devices suitable for preventing the introduction of liquids into the downstream inlet of the chimney while allowing the passage of gases from the chimney;
- an ejection device suitable for ejecting a first scrubbing liquid in the form of at least one pair of liquid curtains from a central region of the scrubber through which the geometrical central axis of the scrubber passes to the circumferential wall of the scrubber - each pair of liquid curtains being the same associated with the pair jetted from the jetting device on both sides of the horizontal plane, and
- a dispensing device suitable for dispensing a second scrubbing liquid in the form of a rain extending from the jetting device to the dispensing device and falling downward in the free space (V100) of the scrubber in which the gas is freely circulated, , wherein the dispensing device comprises a dispenser of at least one stage located flush with each other, dispensing over a cross-section of the scrubber relative to the height, and dispensing each fraction of a corresponding lane,
The rotating device, the protection device, the spraying device and the dispensing device are provided such that the gas to be desulfurized, which comes out of the chimney and circulates upwardly in the interior of the scrubber, comprises a first scrubbing liquid and a second scrubbing liquid provided to capture sulfur dioxide contained in the gas in the scrubber; It is arranged in the interior of the scrubber so as to be placed in contact and to continuously encounter the rotating device, the protective device, the spraying device, and then the dispensing device.

According to the present invention, the gas to be desulfurized moving from the bottom to the top through the scrubber has a velocity profile that is as flat as possible, so that the gas is very effectively desulfurized by the first and second scrubbing liquids dispersed in the scrubber. In addition, embodiments of the present invention maintain economy based on an arrangement that is individually easy to install and operate.

According to a further advantageous feature of the method and installation according to the invention,
- the flow rate of the first scrubbing liquid dispensed by the dispensing device is at least 1.5 times greater than the flow rate of the second scrubbing liquid dispensed by the dispensing device;
- the cross-section of the scrubber under the dispensing device consists of a central part and a peripheral part having the same area, the distribution density of the second scrubbing liquid relative to the central part, i.e. the distribution by the dispensing device in the central part relative to the area of the central part The ratio of the flow rate of the second scrubbing liquid is less than or equal to 0.9 times the distribution density of the second scrubbing liquid on the peripheral portion, ie the ratio of the flow rate of the second scrubbing liquid dispensed by the distribution device in the peripheral portion to the area of the peripheral portion.
- at least two pairs of liquid curtains are ejected by the ejection device with respect to respective horizontal planes located at different heights, horizontal planes belonging to the first pair and a second pair positioned above the first pair, respectively, and respectively related to the first pair Two liquid curtains are intersected with each other, being jetted above and below the horizontal plane associated with the second pair.
- the two liquid curtains of each pair sprayed by the atomizing device form an angle of 50° to 70° with respect to the central axis of the scrubber.
- The first scrubbing liquid and the second scrubbing liquid include or consist of seawater.
- The respective compositions of the first scrubbing liquid and the second scrubbing liquid are not the same.
- the spraying device comprises a single sprayer positioned in the central section of the scrubber and adapted for spraying the first scrubbing liquid in the form of a pair of liquid curtains.
- the spraying device comprises a plurality of sprayers each suitable for spraying a first scrubbing liquid in the form of a pair of liquid curtains, all of which are located in a central region of the scrubber, at least some of the sprayers comprising:
- two liquid curtains injected by a first injector over a horizontal plane associated with a first pair of injectors and by a second injector positioned above the first injector below a horizontal plane associated with a second pair of injectors are mutually exclusive are disposed stepwise along the central axis of the scrubber to intersect, and/or
- They are substantially spaced apart from each other on the same horizontal plane.
- the rotating device comprises blades fixedly distributed around the central axis of the scrubber, in particular 6 to 10 blades are provided.
- the dispensing device comprises a dispenser of a plurality of stages, the stages being located at different heights.
- The protective device consists of a Chinese hat, ie a cone with a semi-conical angle of more than 60°.
- the protective device comprises a coaxial and overlapping apical cone and at least one cone trunk located coaxially below the parietal cone, the parietal cone and the apical trunk both being at least 60° parietal It has a semi-conical angle.
- The installation further comprises a condenser arranged inside the scrubber for the gas to pass after encountering the distribution device.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood by reading the following description, which is provided by way of example only, with reference to the drawings.

1 and 2 are schematic diagrams of the above-described conventional desulfurization plant;
3 is a schematic diagram of a desulfurization method desulfurization plant implementing the desulfurization method according to the present invention;
Fig. 4 is an elevation view of one embodiment of an apparatus belonging to the facility of Fig. 3;
Fig. 5 is an elevational view according to arrow V in Fig. 4;
Fig. 6 is a view similar to Fig. 4 illustrating an alternative embodiment of the apparatus of Fig. 4;
Fig. 7 is an elevation view along arrow VII of Fig. 6;
Fig. 8 is a detailed perspective view of another device belonging to the installation of Fig. 3;
Fig. 9 is a schematic view along the line IX-IX of Fig. 3;

3 shows an installation capable of desulfurizing exhaust gas 1 from a marine propulsion diesel engine mounted on a vessel. The gas 1 contains sulfur oxides, in particular sulfur dioxide (SO ₂ ).

In the installation of FIG. 3 , the gas 1 from the exhaust outlet of the engine described above, and which may be preceded by denitrification, is introduced into the desulfurization scrubber 100 via a chimney 200 .

As schematically shown in FIG. 3 , the scrubber 100 as a whole takes the form of a tower extending in a vertical longitudinal direction during use. The scrubber 100 has a bottom face 101 at its base, and a circumferential wall 102 of the scrubber extends from this bottom face to the top 103 . The main wall 102 of the scrubber 100 defines a geometrical central axis Z100 that extends vertically when the scrubber 100 is in use.

This scrubber 100 is empty in that it lacks an inner liner such as a ring or inner as mentioned at the beginning of this specification.

For example, a chimney 200 made in the form of a sheath or similar duct is disposed below the scrubber 100 and extends substantially vertically to protrude from the bottom surface 101 of the scrubber 100 . The downstream of the chimney 200 penetrates the wall forming the bottom surface 101 around the central axis Z100 of the scrubber 100, and the central axis connecting the rest of the chimney to the bottom surface 101 of the scrubber 100 The downstream inlet 201 of Z100 is substantially coaxial with the main wall 102 of the scrubber. During use, the exhaust gas flows into the bottom surface 101 of the scrubber 100 by the chimney 200, and once inside the scrubber it circulates upwardly from the bottom surface 101 to the top 103, and is purified from the top. It is discharged in the form of a gas (2).

Intake of the gas 1 by the vertical chimney 200 is advantageous in the case of the facility of FIG. 3 installed on a ship, because this configuration occupies less space than the side introduction of the scrubber, and the side introduction is a land-based power plant It is common in the case of scrubbing columns of

In order to provide a size multiple that is not limited in the context of the present invention, the flow rate of the gas 1 is, for example, 50,000 to 200,000 Nm ³ /h, and the inner diameter of the main wall 102 of the scrubber 100 is, for example, For example, 3 to 6 m.

According to one feature of the present invention, the scrubber 100 has a protection device 300 built in the lower part of the main wall 102, which protects the inlet 201 of the chimney 200 so that the liquid in the chimney While preventing the inflow, it serves to allow the gas (1) to be discharged from the chimney. In other words, the protection device 300 prevents any liquid from falling or flowing from the area protruding from the outlet 201 by gravity inside the chimney 200, and at the same time, the gas 1 coming out of the chimney protects the protection device. Allows to be bypassed and diffused into the scrubber 100 . The protection device 300 is important in that it prevents the introduction of liquid from the chimney 200 where the liquid may rise towards the diesel engine from which the gas 1 exits for safety reasons.

Indeed, various embodiments of this protective device 300 are conceivable. A highly open embodiment is preferred to limit pressure loss in the protective device 300 . To this end, one embodiment of the protection device 300 illustrated in FIGS. 4 and 5 is a Chinese hat 301 , ie a cone, which has a semi-conical angle of at least 60°, and has a scrubber ( It is centered on the axis Z100 of 100). A sophisticated embodiment, compared to a Chinese hat 301 , is shown in FIGS. 6 and 7 , which limits the drop of gas 1 towards the main wall 102 of the scrubber 100 . The protective device 300 consists of an assembly 302 comprising a parietal cone 302.1 and two conical trunks 302.2, 302.3 stacked coaxially, the conical elements 302.1, 302.2, 302.3 all being at least It has a parietal cone angle of 60° and is centered substantially on the axis Z100 of the scrubber 100 in the arrangement of FIG. 3 . Of course, in an alternative not shown, the number of conical trunks 302.2, 302.3 may be reduced to one, or conversely may exceed two.

According to one feature of the present invention, the scrubber 100 has a built-in rotating device 400 in the lower part of its main wall 102, which passes through it and the gas 1 coming out of the chimney 200 is protected by a protection device ( It is designed to rotate within the scrubber 100 before reaching 300 ). The rotating device 400 is installed, for example, at the inlet 201 of the chimney 200 as schematically shown in FIG. 3 . Alternatively, the rotating device 400 caps the inlet 201 , or is arranged slightly downstream of the inlet 201 .

Indeed, the embodiment of this rotating device 400 is not limited with respect to the present invention. For example, as schematically shown in FIG. 3 , the rotating device 400 comprises blades 401 for deflecting the gas 1 , which are fixedly disposed within the rotating device 400 , and at the same time possible The case is supported by the central core 402 , and in the facility of FIG. 3 , it is regularly distributed around the central axis Z100 of the scrubber 100 . It is advantageous if 6 to 10 deflection blades 401 are provided. 8 shows in more detail an exemplary embodiment corresponding to the rotating device 400 . As an alternative, not shown, the rotating device 400 may be similar to that used at the inlet of a cyclone separator. Irrespective of this embodiment, the rotating device 400 imparts a gyration motion to the gas 1 circulating through the device, so that the gas 1 is concentrated to one side within the scrubber 100, as shown in FIG. Avoid harm to the opposite party.

According to one feature of the present invention, the scrubber 100 has a built-in spraying device 500 in the running portion of its circumferential wall 102 , which is substantially from the central axis Z100 to the circumferential wall 102 of the scrubber 100 . ) to enable spraying of the scrubbing liquid 3 in the form of a liquid curtain. The jetting device 500 is aperiodic, or, as will be described below, composed of several separate jetting elements, so that the jetting from a region where the curtain of liquid 3 is not strictly limited to the central axis Z100 of the scrubber 100 . It is sprayed by the device 500 and not from the central region of the scrubber 100 passing through the axis Z100. As shown in FIG. 3 , the curtain of each liquid 3 sprayed by the spraying device 500 extends from the spraying device 500 to the main wall 102 of the scrubber 100 , so that the axis Z100 is Each curtain sprayed along covers the entire cross-section of the scrubber 100 outside of the spraying device 500 . As also shown in FIG. 3 , the curtains of liquid 3 are associated in pairs, it can be seen that more than one such pair is possible. The two curtains of each pair are ejected from the spraying device 500 on both sides of the same geometrical horizontal plane H to form an angle strictly less than 90° with respect to the axis Z100. According to a practical but non-limiting embodiment, the two curtains of each pair are substantially symmetrical with respect to the horizontal plane H associated with the pair, which means that the two curtains are α in FIG. 3 with respect to the axis Z100. It is said to form an angle of the same value indicated. According to an advantageous optional dimension, the value of α is between 50° and 70°. In all cases, when the facility of FIG. 3 is in use, the gas 1 that has reached the protection device 300 is circulated upwardly in the scrubber 100, passes through the bottom curtain, and then in the entire cross-section of the scrubber. pass through the upper and middle curtains of each pair of liquids 3 sprayed by the spraying device 500 over, i.e. near the spraying device 500 and near the main wall 102 of the scrubber and between the device and the wall . In this way, the entire flow of gas F from the protection device 300 passes through two liquid curtains or through curtains of each pair of liquids 3 so that the sulfur oxides are transported into the scrubbing liquid 3 by transferring the sulfur oxides into the gas. It becomes possible to trap the contained sulfur oxides.

Accordingly, the spraying device 500 is used to disperse a large amount of the scrubbing liquid 3 without causing a large amount of pressure loss. Thus, the injector 500 cools the gas 1 , ie the gas 1 in the scrubber 100, which is typically between 150° C. and 450° C., has an inlet temperature and a final thermodynamic equilibrium temperature that is typically between 20° C. and 70° C. lowering the temperature of the gas in between, the final temperature value being dependent on the initial temperature and the water content of the gas 1 . In addition, in the running portion of the scrubber 100 , where the injection device 500 is located, the liquid-to-gas ratio has a high value, which makes it possible to quickly capture sulfur oxides, especially sulfur dioxide with a high concentration.

To further increase the desulfurization efficiency, the bottom curtain of each pair is made to intersect the top curtain of each pair before the curtain reaches the main wall 102 of the scrubber 100, so that the liquid ( 3) to take place further atomization, thereby forming an additional transport surface between the liquid 3 and the gas 1, so that each horizontal plane ( A plurality of pairs of curtains of liquid 3 can be sprayed by means of the spraying device 500 while being involved in H).

Indeed, the embodiment of the injection device 500 is not limited in the present invention, which in any case is arranged above the protection device 300 . As an example, as schematically considered in FIG. 3 , the ejection device 500 comprises one or more injectors 501 comprising techniques known per se, wherein the curtain of liquid 3 in each pair comprises injectors ( 501 ), each of which is located in the aforementioned central region of the scrubber 100 , or is located substantially on the central axis Z100 of the scrubber 100 , wherein the injectors 501 are positioned along the axis It is arranged in a stepwise manner along (Z100). Alternatively, it is contemplated that several sprayers 501 are positioned substantially in the same horizontal plane and at a distance from each other, all remaining in the aforementioned central region of the scrubber 100 . For example, three injectors are provided which are arranged at the vertices of a substantially horizontal geometric triangle. Of course, this alternative can be combined with the stage(s) of the injector 501 considered previously. In this case, each stage comprises a plurality of injectors 501 arranged, for example, in a triangular or other arrangement. In all cases, the number of injection stage(s) of the injection device 500 and the number of injectors 501 per injection stage depend not only on the level of purification to be provided but also on the concentration of sulfur oxides in the gas 1 , the number of stages is, for example, 1 to 2, and the number of injectors per stage is, for example, 1 to 3.

With respect to the multiple of the above-mentioned magnitude, the flow rate of the scrubbing liquid 3 injected into each pair of curtains, that is to be said by each injector 501 , is, for example, 30 to 200 m ³ /h. .

According to another feature of the invention, the scrubber 100 incorporates a dispensing device 600 in the upper part of its main wall 102 , which is installed above the jetting device 500 , whereby the jetting device 500 . The scrubbing liquid 3 may be distributed to the distribution device 600 in the form of a rain falling downward in the free space V100 disposed inside the circumferential wall 102 of the scrubber 100 of the . In this free space V100, the gas 1 passing through the curtain of liquid 3 freely circulates upwardly inside the scrubber 100 and meets the countercurrent lane formed by the scrubbing liquid 3, This provides a complementary purification of the gas by entrapment in the liquid 4 of sulfur oxides still present in the gas.

This embodiment of the dispensing device 600 in the present invention is not limited. As an example, as schematically illustrated in FIG. 3 , the dispensing device 600 comprises a dispenser 601 known per se, which is, for example, a spray nozzle, a spray bar, a spray head, and the like. If possible, and as also shown in FIG. 3 , the distributor 601 may be arranged in one or more, for example four, two stages in vertical succession. In all cases, on each of these stages, all of these stages are located substantially at the same height, ie at the same level along the axis Z100, and the number of said stages is, for example, 5 to 30. Dispenser 601 is arranged over the cross-section of the scrubber with respect to said height. In this way, and by providing that each dispenser 601 of each stage dispenses a portion of the lane from the liquid 4, the lanes from the liquid 4 obtained below the dispensing device 600 are Even if the distributor 601 is not strictly homogeneous, it falls over the entire cross-section of the free space V100 .

With respect to the multiple of the above-mentioned magnitude, the flow rate of the scrubbing liquid 3 dispensed by each stage of the dispensing device 600 is about 200 m ³ /h.

Of course, multiples and values of these sizes are not limited in the present invention. Depending on the size of the desulphurization plant these values can be adjusted and can be much greater or less than previously given values.

The composition of each of the scrubbing liquids 3 and 4 is not limited in the present invention. Each of the liquids 3 and 4 preferably comprises seawater and, if possible, doped with an alkaline reagent. In this case, one and/or the other of the scrubbing liquids 3 , 4 may consist of limestone or a lime suspension or a sodium solution. Furthermore, according to a first operability, the respective compositions of the scrubbing liquids 3 , 4 are identical. According to an alternative operability, the composition of the scrubbing liquid 4 is not identical to that of the scrubbing liquid 3 , in particular fresh seawater which may or may not be doped with the scrubbing liquid 4 , for example an alkaline reagent. while the scrubbing liquid 3 may be a recirculating liquid, in particular partially depleted seawater. In all cases, the total amount of scrubbing liquid 3 , 4 injected by the injection device 500 and dispensed by the dispensing device 600 is the flow rate of, for example sulfur dioxide, in the gas 1 (eg , in kg/h).

According to one optional advantageous feature of the invention, the scrubber 100 has a built-in condenser 700 , which is capable of retaining droplets in the clarified tube 2 in a manner known per se, These droplets move to the outside of the scrubber 100 in the absence of the condenser. A condenser 700 is positioned above the distribution device 600 to allow the gas 1 to pass therethrough during use, and the gas 1 is circulated upwardly inside the scrubber 100 after reaching the distribution device 600 .

This embodiment of the condenser 700 is not limited in the present invention. For example, the condenser 700 is configured as a basket having a bracket.

The installation of FIG. 3 is an injection device 500, with a concentrated vertical introduction of gas 1 into the bottom 101 of the scrubber through a chimney 200 and rotation of the gas inside the scrubber by means of a rotation device 400. Under the combined effect of the curtain of scrubbing liquid 3 being sprayed by and the lanes of scrubbing liquid 4 being dispensed by the distribution device 600, due to the stabilization of the flow of said gas inside the scrubber 100, the gas ( It is particularly effective for desulfurization of 1). Indeed, the velocity profile of the gas 1 , which is necessarily very inhomogeneous immediately downstream of the protection device 300 , is gradually and rapidly rehomogenized under the combined action of the injection device 500 and the distribution device 600 . In addition, the rotation of the gas 1 by the rotating device 400 prevents vibrational instability of the gas 1 in particular between two diametrically opposed zones of the scrubber 100 .

Since the liquid 3 is sprayed in the form of a curtain whereas the liquid 4 is distributed in the form of a lane, the contact arrangement of the gas 1 and the scrubbing liquid 3 is the same as the contact arrangement of the gas 1 and the scrubbing liquid 4 . It will be understood that is a different type. This difference in the type of contact favors the desulfurization efficiency and also allows the jetting device 500 to inject a flow rate of liquid 3 that is much greater than the flow rate of the liquid 4 dispensed by the dispensing device 600 , , thus the flow rate of the liquid 3 is 1.5 or even 2 times greater than the flow rate of the liquid 4 . In this way, desulphurization is done with more liquid 3 than liquid 4 , and thus, on the one hand, can limit the flow rate of liquid 4 (which has the greatest effect on the pressure loss inside scrubber 100 ). and, on the other hand, when the gas begins to circulate inside the scrubber, ie when a high value of the liquid to gas ratio is desired for treating gases with high concentrations of sulfur dioxide. flow can be increased.

As an optional and advantageous refinement, the dispensing device 600 is designed such that the dispensing density of the scrubbing liquid 4 is lower at the center of the scrubber than at the periphery of the scrubber. Indeed, this refinement is based on the dedicated selection and/or placement of the distributors 600 of the dispensing device 601 , which means that the distributors 600 are not necessarily all identical, and the dedicated placement is It is said that the position of the distributor 601 is not necessarily uniform. In other words, the number and type of distributors 601 per square meter may vary across the cross-section of the scrubber 100 .

In order to better understand this point, Fig. 9 shows that the cross section of the scrubber 100 in the free space V100 of the scrubber is virtually two parts, that is, the central part S100.1 through which the central axis Z100 of the scrubber passes. ) and the central part (S100.1) indicate that it is divided into the peripheral part (S100.2) in the whole circumference, and the area of each of the central part (S100.1) and the peripheral part (S100.2) is equal to each other, The distribution density of the scrubbing liquid 4 in the central portion S100.1 (ie, relative to the area of the central portion S100.1), the scrubbing liquid dispensed by the dispensing device 600 in the central portion S100.1 The ratio of the flow rate of (4) (eg, ^{denoted as m 3} /m ² /h) is the distribution density of the scrubbing liquid 4 in the peripheral portion S100.2 (ie, the peripheral portion S100.2) is at most 0.9 times the ratio (expressed in equal units) of the flow rate of the scrubbing liquid 4 dispensed by the dispensing device 600 in the peripheral part S100.2 to the area of .

Therefore, the droplet of the lane of scrubbing liquid 4 falling into a part of the space V100 (the cross section of which corresponds to the peripheral part S100.2) is the rest of the space V100 (ie the central part S100. The portion of space having a cross section corresponding to 1)) is more than falling into it. Thus, the liquid 4 dispensed into the portion of the space V100 associated with the peripheral portion S100.2 creates greater friction against the gas 1 circulating upward in that portion of the space V100, A re-equilibration with respect to the remainder of (V100) is achieved so that the influence of the injection device 500 and the protection device 300 on the gas 1 is at least partially compensated.

In practice, the scrubbing liquid ( 4) can be adjusted manually or automatically.

Thus, an overall profile for the ratio of liquid to gas which is more favorable for desulfurization of gas 1 is again obtained inside scrubber 100 .

Example:

The present invention was tested with the following specifications.

The facility of FIG. 3 treats an exhaust gas 1 of ^{105,000 Nm 3} /h entering the bottom 101 of the scrubber 100 by way of a chimney 200 at a temperature of 390° C. The scrubber 100 has, at its peripheral wall 102 , an inner diameter of 3200 mm and a total height of about 10 m. The chimney 200 has an inner diameter of 1800 mm. The rotating device 400 comprises eight turning blades 401 . The protection device 300 is in the form of a Chinese hat 301 of FIGS. 4 and 5 . Each of the four stage type injectors 501 sprays a scrubbing liquid ^{3 of 80 m 3 /h.} A single stage dispenser 601 dispenses 200 m ³ /h of scrubbing liquid 4 . The condenser 700 has a bracket.

Running this embodiment, it is possible to observe a rapid homogenization of the velocity profile of the gas 1 inside the scrubber 100 , which profile is very non-uniform immediately downstream of the protection device 300 , whereas the free space V100 ) is substantially uniform.

Claims (15)

A method for wet desulfurization of exhaust gas of a marine engine, comprising:
The gas 1 to be desulfurized is introduced into the scrubber 100 through a vertical chimney 200 protruding substantially from the center of the bottom face 101 of the scrubber,
The gas (1) is circulated upwardly inside the scrubber (100) which is installed to come into contact with the first scrubbing liquid (3) and the second scrubbing liquid (4) provided to capture the sulfur dioxide contained in the gas,
The gas is in the scrubber
- Rotating device 400 for passing the gas 1 while rotating in the scrubber 100,
- a protective device (300), which prevents the introduction of liquid into the downstream inlet (201) of the chimney (200) while maintaining the circulation of the gas (1);
- a spraying device 500 , wherein the spraying device 500 is in the form of at least a pair of liquid curtains from the central region of the scrubber 100 through which the geometrical central axis Z100 of the scrubber passes to the circumferential wall 102 of the scrubber a jetting device 500 , then the first scrubbing liquid 3 being jetted from the jetting device on both sides of the same horizontal plane H associated with the pair, the liquid curtains of each pair
- A distribution device 600 separated by a free space V100 in which gas freely circulates upwardly in the scrubber from the injection device 500 inside the scrubber 100, wherein the distribution device comprises the free space ( Dispensing a second scrubbing liquid 4 in the form of a rain falling downward in V100, said dispensing device dispensing over a cross-section of said scrubber in relation to a height, and dispensing a corresponding fraction of said lane Dispensing apparatus 600 , comprising a dispenser 601 of at least one stage positioned flush, each dispensing
meets successively with
Method of wet desulfurization of exhaust gases of marine engines. The method of claim 1,
the flow rate of the first scrubbing liquid (3) dispensed by the dispensing device (500) is at least 1.5 times greater than the flow rate of the second scrubbing liquid (4) dispensed by the dispensing device (600);
Method of wet desulfurization of exhaust gases of marine engines. 3. The method according to claim 1 or 2,
The cross section of the scrubber 100 under the dispensing device 600 consists of a central portion S100.1 and a peripheral portion S100.2 having the same area, the second scrubbing liquid relative to the central portion ( 4), i.e. the ratio of the flow rate of the second scrubbing liquid dispensed by the dispensing device 600 in the central portion to the area of the central portion is the distribution density of the second scrubbing liquid on the peripheral portion , that is, less than or equal to 0.9 times the ratio of the flow rate of the second scrubbing liquid dispensed by the dispensing device in the peripheral portion to the area of the peripheral portion.
Method of wet desulfurization of exhaust gases of marine engines. 3. The method according to claim 1 or 2,
At least two pairs of liquid curtains are jetted by the jetting device 500 with respect to respective horizontal planes H located at different heights, each belonging to a first pair and a second pair located above the first pair, and two liquid curtains each intersecting each other, being jetted above the horizontal plane associated with the first pair, and jetted below the horizontal plane associated with the second pair;
Method of wet desulfurization of exhaust gases of marine engines. 3. The method according to claim 1 or 2,
Each of the two liquid curtains of the pair sprayed by the spraying device 500 forms an angle α of 50° to 70° with respect to the central axis Z100 of the scrubber 100,
Method of wet desulfurization of exhaust gases of marine engines. 3. The method according to claim 1 or 2,
wherein the first scrubbing liquid (3) and the second scrubbing liquid (4) comprise seawater,
Method of wet desulfurization of exhaust gases of marine engines. 3. The method according to claim 1 or 2,
the respective compositions of the first scrubbing liquid (3) and the second scrubbing liquid (4) are not the same;
Method of wet desulfurization of exhaust gases of marine engines. A facility for wet desulfurization of exhaust gas of a marine engine, comprising:
The equipment is
- the scrubber 100 in the bottom surface 101 from which a vertical chimney 200 for the suction of the gas 1 into the scrubber protrudes substantially from the center,
- a rotating device ( 400 ) suitable for passing the gas ( 1 ) coming out of the chimney ( 200 ) to rotate the gas in the scrubber ( 100 );
- a protective device (300) suitable for preventing the introduction of liquid into the downstream inlet (201) of the chimney (200) while allowing the passage of the gas (1) exiting the chimney;
- a first scrubbing liquid 3 in the form of a curtain of at least one pair of liquid curtains from a central region of the scrubber 100 through which the geometrical central axis Z100 of the scrubber passes, as an injection device 500 . ), wherein each pair of said liquid curtains is ejected from said spraying device on both sides of the same horizontal plane (H) associated with said pair, and
- A distribution device 600 separated by a free space (V100) in which gas freely circulates upwardly in the scrubber from the injection device (500) inside the scrubber (100), wherein the distribution device is the free space (V100) ) suitable for dispensing a second scrubbing liquid (4) in the form of a rain falling downward in the said dispensing device, said dispensing device being dispensed over a cross-section of said scrubber in relation to the height, and Dispensing device (600), comprising a dispenser (601) of at least one stage positioned at the same level, each dispensing fractions
including,
The rotation device 400 , the protection device 300 , the injection device 500 , and the distribution device 600 include the gas to be desulfurized 1 that comes out of the chimney 200 and circulates upwardly inside the scrubber. ) placed in contact with the first scrubbing liquid (3) and the second scrubbing liquid (4) provided to capture the sulfur dioxide contained in the gas in the scrubber, and the rotating device, the protecting device, the spraying device. , arranged inside the scrubber 100, so as to meet continuously with the dispensing device,
Equipment for wet desulfurization of exhaust gas from marine engines. 9. The method of claim 8,
The spraying device (500) comprises a single sprayer (501) located in a central region of the scrubber (100) and suitable for spraying the first scrubbing liquid (3) in the form of a pair of liquid curtains,
Equipment for wet desulfurization of exhaust gas from marine engines. 9. The method of claim 8,
The spraying device 500 comprises a plurality of sprayers 501 each suitable for spraying the first scrubbing liquid 3 in the form of a pair of liquid curtains, all located in a central region of the scrubber 100 . including,
At least some of the injectors,
- to a second injector which is injected by said first injector above said horizontal plane H associated with said first pair of injectors and which is positioned above said first injectors below said horizontal plane associated with said second pair of injectors are arranged stepwise along the central axis Z100 of the scrubber 100 so that two liquid curtains sprayed by the
- spaced apart from each other in substantially the same horizontal plane,
Equipment for wet desulfurization of exhaust gas from marine engines. 11. The method according to any one of claims 8 to 10,
The rotating device (400) comprises blades (401) fixedly distributed around a central axis (Z100) of the scrubber (100).
Equipment for wet desulfurization of exhaust gas from marine engines. 11. The method according to any one of claims 8 to 10,
The dispensing device (600) comprises a plurality of stages of the dispenser (601), the stages being positioned at different heights, respectively.
Equipment for wet desulfurization of exhaust gas from marine engines. 11. The method according to any one of claims 8 to 10,
The protection device 300 consists of a Chinese hat 301, that is, a cone with a semi-conical angle of 60° or more,
Equipment for wet desulfurization of exhaust gas from marine engines. 11. The method according to any one of claims 8 to 10,
The protective device 300 comprises a coaxial and overlapping apical cone 302.1 and one or more cone trunks 302.2, 302.3 located coaxially below the parietal cone 302.1, wherein the parietal cone and the conical trunk both have a parietal semicone angle of at least 60°,
Equipment for wet desulfurization of exhaust gas from marine engines. 11. The method according to any one of claims 8 to 10,
The installation further comprises a condenser (700) disposed inside the scrubber (100) through which the gas (1) is passed after encountering the distribution device (600).
Equipment for wet desulfurization of exhaust gas from marine engines.

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