Method and system for purifying contaminated marine exhaust gas purification fluid

Abstract

The present invention provides a method (100) for purifying a contaminated cleanup liquid, wherein the contaminated cleanup liquid is a contaminated marine exhaust gas cleanup liquid. The present invention includes a) a step of preparing the contaminated cleanup liquid (101), b) a step of adding a solid porous adsorbent to the contaminated cleanup liquid (102), c) a step of reacting the adsorbent with the pollutants in the contaminated cleanup liquid (103), d) a step of separating the contaminated cleanup liquid with a centrifuge (104), and e) a step of discharging the clean liquid phase and the pollutant phase from the centrifuge (105). The present invention further provides a system (1) for purifying a contaminated cleanup liquid, wherein the contaminated cleanup liquid is a marine exhaust gas cleanup liquid.

Description

Technical Field

[0001] The present invention relates to the field of exhaust gas purification systems and methods.

Background Art

[0002] Today's shipping industry is striving to reduce harmful emissions, such as those resulting from the combustion of fuel in engines, in order to minimize environmental impact and meet current and future emission regulations.

[0003] Part of this is the reduction of nitrogen oxides (NO , ,

[0006] , ) emissions from marine engines. This can be achieved by implementing exhaust gas recirculation (EGR), where a portion of the exhaust gas is recirculated to the engine's combustion chamber. However, the amount of soot and particles in the high-temperature exhaust gas needs to be reduced. Therefore, it is particularly desirable to cool and purify the exhaust gas, which can be done by using a purification liquid. However, this generates contaminated purification liquid.

[0004] Another objective is to reduce sulfur oxide (SO x ) emissions from ships. Sulfur oxides are produced by the combustion of fuels containing sulfur residues. The amount of sulfur oxides in the exhaust gas can be reduced by exhaust gas purification, for example, by using a scrubber. The process of purifying the exhaust gas by adopting a scrubber also generates contaminated purification liquid.

[0005] Equipment for purifying contaminated purification liquid includes, for example, membrane and filter technologies, air flotation devices, and centrifuges. However, equipment that relies on filter technology has drawbacks in terms of the need for monitoring, inspection, and replacement of filter components.

[0006] Centrifugal separators are generally used to separate liquids and / or solids from liquid or gaseous mixtures, utilizing the principle of density differences between fluid and solid phases to recover fractions separated at different radii from the axis of rotation. For an example of the use of centrifuges to purify contaminated liquids, see, for example, International Publication No. 2011 / 104302.

[0007] However, new regulations on NOx and SOx emissions require better purification processes for contaminated wastewater. Therefore, there is a need for improved methods and systems for purifying contaminated marine exhaust gas purifying fluid in this technology. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2011 / 104302 [Non-patent literature]

[0009] [Non-Patent Document 1] 2015 Guidelines for Exhaust Gas Cleaning Systems, MEPC 259 (68) [Overview of the project] [Problems that the invention aims to solve]

[0010] The main objective of the present invention is to provide a system and method for purifying contaminated liquids, such as contaminated water used on board ships to reduce NOx or SOx emissions. [Means for solving the problem]

[0011] A first aspect of the present invention is a method for purifying a contaminated purification liquid, wherein the contaminated purification liquid is a contaminated marine exhaust gas purification liquid. a) The step of preparing the above-mentioned contaminated cleansing liquid, b) The step of adding a solid porous adsorbent to the above-mentioned contaminated cleanup liquid, c) A step of reacting the above adsorbent with the contaminants in the above contaminated cleanup liquid, d) A step of separating the contaminated cleanup liquid using a centrifuge, e) A step of discharging the clean liquid phase and the contaminant phase from the centrifuge described above. A method is provided that includes this.

[0012] Marine exhaust gas purification fluid refers to a purification fluid used on board a ship to purify exhaust gases from an engine. Purification may be carried out, for example, in an EGR unit or in a SOx scrubber. The purification fluid used to purify the exhaust gas is therefore the contaminated marine exhaust gas purification fluid, or simply the “contaminated purification fluid,” in this disclosure.

[0013] The purification solution may be an aqueous solution, such as water, tap water, freshwater, or desalinated seawater.

[0014] The decontaminated liquid prepared in step a) is therefore a decontaminated liquid containing contaminants such as solid and / or liquid particles consisting of organic or inorganic combustion residues such as sulfur oxide residues, soot, partially oxidized and unoxidized marine fuel oil, and salts from metal oxides. The decontaminated liquid may therefore also be water contaminated with oil and contaminant particles such as organic contaminant particles.

[0015] In the embodiment of the first aspect, the contaminated cleansing liquid contains at least 20 mg / l of oil, such as at least 50 mg / l of oil, at least 100 mg / l of oil, etc.

[0016] For example, the contaminated cleanup solution may contain approximately 20-300 mg / l of oil, such as 25-200 mg / l of oil.

[0017] In the embodiment of the first aspect, the contaminated cleansing liquid contains a suspended solids content of approximately 25 to 2000 mg / l, such that it is between 50 and 1500 mg / l.

[0018] As an example, the amount of suspended solids in the pollution purification liquid may be between 50 and 150 mg / l.

[0019] In an embodiment of the first aspect, the pollution purification liquid contains an oil content of 25 to 200 mg / l and a suspended solid amount of about 50 to 1500 mg / l.

[0020] The solid porous adsorbent added in step b) may be in the form of a slurry, powder or granule. The solid porous adsorbent may have a highly porous structure that attracts molecules or ions adhering to its surface.

[0021] The solid porous adsorbent may be capable of adsorbing pollutants in the pollution purification liquid so as to be capable of adsorbing oil. The pollutants may be adsorbed into the adsorbent, such as on the outer surface of the adsorbent and / or within the pores of the adsorbent.

[0022] Step b) may be performed after the purification liquid has passed through the EGR unit or the SOx scrubber.

[0023] Step c) of reacting the adsorbent with the pollutants in the pollution purification liquid may be performed for at least a specific time interval, such as at least 10 minutes, at least 15 minutes, at least 25 minutes. As an example, step c) may consist of reacting the adsorbent with the pollutants in the pollution purification liquid for 5 to 30 minutes.

[0024] The term "reacting the adsorbent" may mean adsorbing it onto the surface of the adsorbent and / or into the pores of the adsorbent for that purpose.

[0025] The centrifuge in step d) may be a disc stack centrifuge. Therefore, the centrifuge may be provided with a stack of separation discs, such as frustoconical separation discs, to increase the separation performance. Therefore, step d) may consist of supplying the contaminated scrubber liquid to the inlet of the centrifuge so that the pollution purification liquid can be separated into a clean liquid phase and a pollutant phase by the adoption of the disc stack arranged in the centrifuge.

[0026] Step e) for discharging the clean liquid phase may consist of continuously discharging the clean liquid phase, and discharging the contaminant phase may be continuous or intermittent discharge from the centrifuge.

[0027] The solid porous adsorbent added in step b) may be discharged in the contaminant phase, such as in the sludge phase or in the contaminant liquid phase.

[0028] The clean liquid phase may contain reduced amounts of contaminants, but may still contain low levels of them. Similarly, the contaminant phase separated from the contaminated cleansing liquid may still contain a certain amount of the cleansing liquid.

[0029] In embodiments, the method further includes step f) returning the clean liquid phase, or at least a portion of the clean liquid phase, to an upstream position of the centrifuge. Such a position may be a tank located upstream of the centrifuge.

[0030] The terms upstream and downstream may be used to describe directions or locations observed along the flow direction of the purified fluid. Upstream may be understood as being closer to, for example, an EGR unit or a SOx scrubber.

[0031] As an example, step e) may further include returning the clean liquid phase, or at least a portion of the clean liquid phase, to a tank upstream of the centrifuge. The tank may be the tank to which the solid porous adsorbent is added, or a tank located upstream of the location where the solid porous adsorbent is added.

[0032] In some embodiments, the clean liquid phase is further processed with a filter, such as a membrane filter. This may be done before the clean liquid phase is returned to the upstream position of the centrifuge. This may further reduce the amount of any residual contaminants in the clean liquid phase.

[0033] A first aspect of the present invention is based on the insight that a solid porous adsorbent may be effective in adsorbing contaminants in contaminated water so that they can be more easily separated by a centrifuge. For example, it has been found that oil present in a contaminated water can be adsorbed to such an extent that it remains on or within the adsorbent even when subjected to a very strong centrifugal field in a centrifuge.

[0034] This is particularly important for modern engines that meet Tier II and Tier III NOx regulations. Such engines produce only small amounts of soot, making the purifying fluid difficult to clean. High oil concentrations can be present in the contaminated purifying fluid, resulting in low solid phase density, making it difficult to precipitate using a centrifuge without the addition of the adsorbent according to the present invention. Furthermore, with respect to exhaust gas recirculation (EGR) systems, it has been observed that an oil film can be present on the contaminated purifying fluid when the suspended solids concentration is low (TSS < 100 mg / l) and the oil concentration is high (C_oil > 200 PPM). This oil film was previously very difficult to remove using prior art methods involving centrifuges, such as when the centrifuge is configured as a clarifier for liquid-solid separation.

[0035] Furthermore, because the engine burns heavy fuel oil (HFO) and operates in a so-called closed-loop mode, high concentrations of heavy metals are present in the contaminated cleanup fluid generated from the SOx scrubber. It has been found that high levels of harmful heavy metals, such as nickel, vanadium, and zinc, can be separated from the contaminated cleanup fluid using adsorbents.

[0036] In the embodiment of the first aspect, step c) is performed while the contaminated cleanup liquid is being stirred.

[0037] Stirring may promote the adsorption of contaminants onto the added adsorbent. Stirring may be performed during the addition of the adsorbent in step c) or may begin immediately after the addition of the adsorbent.

[0038] For example, the addition in step b) is performed on the tank containing the contaminated purified water. Therefore, stirring may be performed in the tank to which the adsorbent is added.

[0039] However, agitation does not need to be performed in the tank. As a further example, the addition in step b) is to the piping system through which the contaminated purified water is transported. Therefore, agitation of the contaminated purified liquid may be performed, for example, by transporting the contaminated purified liquid in pipes. The addition of the adsorbent may therefore be during the recirculation of the contaminated purified liquid, for example, during recirculation through a piping system returning from one tank to the same tank. Therefore, the adsorbent may be added to the contaminated purified liquid while it is being transported, i.e., while the contaminated purified liquid is moving (flowing).

[0040] In an embodiment of the first aspect, the method further includes the step of adding a coagulant and / or a coagulant to the contaminated cleanup liquid before step d).

[0041] The flocculant and / or coagulant may be added between steps c) and d), i.e., after the addition of the contaminated remediation liquid and its reaction with the adsorbent, but before the supply of the contaminated remediation liquid to the centrifuge.

[0042] Coagulants and / or solidifying agents promote the agglomeration of particles in contaminated liquids, thus facilitating the separation of contaminants by centrifuge. As an example, the coagulant and / or solidifying agent may be a polymer, such as a polyelectrolyte. Therefore, the coagulant may be anionic, cationic, or nonionic polymer coagulants with different properties, for example, in terms of physical length, bonding, and strength. As an example, the coagulant may be a cationic coagulant.

[0043] As mentioned above, the centrifuge used may be a disc stack centrifuge. The disc stack centrifuge may have a single liquid outlet for the separated liquid phase and an outlet for the separated sludge phase. Therefore, the disc stack centrifuge may also be of the clarifier type.

[0044] Consequently, in the embodiment of the first aspect, the separation in step d) yields a single contaminant phase and a single liquid phase, the single liquid phase being discharged as a clean liquid phase in step e).

[0045] Therefore, the pollutants in the contaminated purifying liquid may be discharged in the same single pollutant phase. For example, pollutants in the form of oil and particles may be discharged in the same pollutant sludge phase. Furthermore, since the added adsorbent may agglomerate with the oil and particles in the contaminated purifying liquid, they may also be removed in a single pollutant phase, i.e., the sludge phase, using a centrifuge.

[0046] However, a centrifuge with two liquid outlets may also be used. For example, a three-phase centrifuge may be used. Such a separator may be arranged to separate the contaminated cleanup liquid into a clean liquid phase such as an aqueous phase, a contaminant liquid phase such as an oil phase, and a contaminant sludge phase.

[0047] In the embodiment of the first aspect, the decontamination fluid prepared in step a) is derived from recirculated decontamination fluid used in an exhaust gas recirculation (EGR) unit for marine applications.

[0048] In EGR systems for marine applications, a portion of the exhaust gas is recirculated to the engine after the cooling and purification process. The purification and cooling process involves the use of an EGR unit, which typically includes an EGR cooling unit that sprays a purification fluid, such as fresh water, onto the recirculated exhaust gas. Only excess contaminated purification fluid may need to be recirculated and discharged from the EGR unit for purification. The bleed-off purification fluid may consist of excess liquid, such as water, from the combustion process that accumulates in the EGR system.

[0049] Therefore, step a) may consist of preparing a bleed-off contaminated cleanup liquid from the EGR unit's EGR drain tank, and the addition of the adsorbent in step b) may be applied to the contaminated cleanup liquid in the EGR drain tank.

[0050] "Bleed-off contaminated liquid" refers to contaminated liquid that is discharged from the EGR system and is therefore not returned to the EGR system but is instead purified and treated elsewhere. The centrifuge used in step d) may therefore be part of the water treatment system (WHS) for the EGR system.

[0051] Furthermore, the clean liquid phase discharged from the centrifuge in step e), i.e., purified water, may be sent directly overboard to a holding tank for later disposal, or recirculated and returned to the EGR drain tank. Consequently, the clean liquid phase discharged in step e) may meet international requirements for bleed-off water, such as those specified in, for example, the 2015 Guidelines for Exhaust Gas Cleaning Systems, MEPC 259 (68).

[0052] As an example, step e) may further include discharging the clean liquid phase overboard.

[0053] As a further example, step e) may further include discharging the cleaning liquid into a tank for later disposal.

[0054] As a further example, step e) may further include recirculating the clean liquid phase into a tank for further processing in a centrifuge.

[0055] In the embodiment of the first aspect, the contaminated cleanup liquid prepared in step a) is derived from the recirculated cleanup liquid used in the SOx scrubber.

[0056] During the combustion of fossil fuels in marine engines, exhaust gas containing sulfur oxides (SOx) is formed. The exhaust gas may be passed through a SOx scrubber and / or a wet electrostatic precipitator and washed with a purification liquid, thereby capturing the contaminants in the exhaust gas in the liquid. The purification liquid is usually circulated through a circulation tank in a circulation loop, and a centrifuge in a water treatment system (WHS) may be used to purify the contaminated purification liquid and send it back to such a circulation tank. Alternatively, a centrifuge in a water treatment system (WHS) may be used to purify the contaminated purification liquid and send it overboard or to a tank for later disposal, i.e., the purification liquid may be released from the circulation loop.

[0057] Therefore, as an example, step a) may consist of preparing the contaminated clean liquid used in the SOx scrubber in the circulation tank, and step e) may further include recirculating the clean liquid phase back into the circulation tank.

[0058] The circulation tank may also be a tank for holding the purified liquid that will later be used in the SOx scrubber.

[0059] As a further example, step a) may consist of preparing the contaminated clean liquid used in the SOx scrubber in a circulation tank, and step e) may further include sending the cleaned liquid overboard or to a tank for later disposal.

[0060] In the embodiment of the first aspect, the solid porous adsorbent used is selected from the group consisting of activated carbon, zeolite, iron oxide-coated sand, silica gel, nanoadsorbents, graphene-based adsorbents, and natural adsorbents.

[0061] As an example, the solid porous adsorbent used may be selected from the group consisting of activated carbon, zeolite, and graphene-based adsorbents.

[0062] As an example, the solid porous adsorbent may be activated carbon. The activated carbon may be treated from carbon to have a high surface area.

[0063] As an example, the solid porous adsorbent used may be added together with other additives, such as in a composition, a mixture, or dissolved in another additive. As described above, solid porous adsorbents such as activated carbon may be added in the form of, for example, a slurry, powder, or granules.

[0064] For example, a solid porous adsorbent may have an average particle size of less than 1 mm, such as less than 0.5 mm or less than 100 μm. This allows the use of a disk stack separator, but if the particles are too large, they will clog the disk stack. Therefore, in the embodiment, granules of solid porous adsorbent are not used because they usually have an average particle size of more than 1 mm.

[0065] Furthermore, step b) may consist of adding a solid porous adsorbent at a concentration of less than 2 g / L, such as less than 1 g / L, less than 0.7 g / L, around 0.5 g / L, etc.

[0066] Therefore, in embodiments of the present invention, a solid porous adsorbent such as activated carbon is added to the contaminated cleanup liquid in step b), having an average particle size of less than 1 mm, such as less than 100 μm, and added to the contaminated cleanup liquid at a concentration of less than 2 g / L.

[0067] Therefore, step b) may consist of adding activated carbon in powder form at a concentration of less than 2 g / L, such as less than 1 g / L, less than 0.7 g / L, or around 0.5 g / L.

[0068] Furthermore, step b) may consist of adding activated carbon to the contaminated cleanup liquid at a concentration of 50 to 300 mg / l, such as between 100 and 250 mg / l.

[0069] Activated carbon may have an average particle size between 2 and 200 μm, such as between 5 and 150 μm.

[0070] Activated carbon can also be finely powdered activated carbon.

[0071] Activated carbon is at least 500m 2 Like / g, at least 300m 2 Fine activated carbon with a surface area of ​​ / g may also be used.

[0072] For example, activated carbon is at least 500m 2 Fine activated carbon with a surface area of ​​ / g and an average particle size (diameter) of less than 75 μm may also be used.

[0073] In the embodiment, the solid porous adsorbent is added as activated sludge or activated emulsion.

[0074] A second aspect of the present invention is provided, a system for purifying a contaminated liquid, wherein the contaminated liquid is a marine exhaust gas purification liquid. This system is - A centrifuge arranged to separate at least one contaminated phase and a clean phase from the above contaminated purification liquid, - An injection unit comprising a solid porous adsorbent, positioned upstream of the centrifugal separator for adding the solid porous adsorbent to the contaminated purification liquid, - The system includes a transport means for transporting the contaminated cleanup liquid to the centrifuge to which the above-mentioned adsorbent has been added.

[0075] The terms and definitions used in relation to the second aspect are the same as those given in relation to the first aspect above.

[0076] This system may therefore be used to carry out the method of the first embodiment.

[0077] The centrifuge may be as described in relation to the first embodiment above.

[0078] A centrifuge is arranged to separate at least one contaminated phase and a clean phase from the contaminated purifying liquid. The centrifuge may therefore be arranged to separate the contaminated purifying liquid into a single liquid phase and a sludge phase, or into two liquid phases and a sludge phase. The centrifuge may comprise a fixed frame and a drive member configured to rotate a centrifugal bowl within the frame. The centrifugal bowl may enclose a separation space. The separation space may include a stack of separation disks positioned centrally around a rotation axis. Such separation disks form surface-expanding inserts in the separation space. The separation disks may have the form of a frustocone, i.e., the stack may also be a stack of truncated cone separation disks.

[0079] The injection unit may include a chemical or membrane injection pump for injecting the adsorbent. The injection unit may further include a mixer arranged to mix the solid porous adsorbent with, for example, water before injection. However, if the adsorbent is already a slurry, only an injection pump may be required.

[0080] As an example, the injection unit may comprise a reservoir containing a solid porous adsorbent, a powder mixer, and a freshwater supply. The injection unit may further comprise a mixing unit, such as an agitator mixer, for mixing the powder adsorbent with freshwater before supply. The injection unit may further comprise a membrane injection pump and piping to the injection location.

[0081] As a further example, the injection unit may include a reservoir containing the powder adsorbent as a slurry, a membrane injection pump, and piping to the injection location.

[0082] The solid porous adsorbent may be as described in relation to the first embodiment above.

[0083] The means of transport may include, for example, a pump such as a water supply pump for transporting the contaminated cleanup liquid to the inlet of the centrifuge.

[0084] In a second embodiment, the system further comprises a tank capable of transporting the contaminated purifying liquid to the centrifuge. Therefore, the system may also include piping connecting the inlet of the centrifuge to the tank. A transport means is provided to transport the contaminated purifying liquid, to which the adsorbent has been added, from the tank to the centrifuge.

[0085] For example, the injection unit may be arranged to add the solid porous adsorbent to the tank, and the tank may further include stirring means for stirring the contaminated cleanup liquid inside the tank.

[0086] The agitator may therefore be positioned to mix the components in the tank, namely the contaminated cleanup liquid and the added adsorbent. The agitation means may include agitator blades positioned to rotate within the tank. The agitator blades may be mounted on a shaft that is rotated, for example, using a motor. The use of an agitated tank therefore promotes the adsorption of contaminants in the contaminated cleanup liquid onto the adsorbent, reduces the sedimentation time for the adsorbent in the tank, and thereby increases the adsorption capacity.

[0087] For example, the tank may be a circulation tank in which contaminated scrubber water can be circulated to and from the centrifuge. Thus, the centrifuge and the circulation tank may form a first recirculation system.

[0088] In a second embodiment, the system further comprises a recirculation system arranged to recirculate the contaminated cleanup liquid in the tank before transporting it to the centrifuge, and an injection unit is arranged to add the solid porous adsorbent to the recirculation system.

[0089] Therefore, the tank may be part of a recirculation system that does not involve a centrifuge. In this case, the adsorbent may be added to such a recirculation system. The flow of the contaminated liquid in such a recirculation system can thus promote the mixing of the adsorbent with the contaminants in the contaminated liquid, thereby promoting the adsorption of the contaminants onto the adsorbent.

[0090] In a second embodiment, the system further comprises a pretreatment unit upstream of the centrifuge and transport means for transporting the contaminated cleanup liquid to the centrifuge via the pretreatment unit to the centrifuge. Such a pretreatment unit may include an injection unit for a coagulant and / or solidifying agent. The injection unit for the coagulant and / or solidifying agent may therefore be connected to a supply unit containing the coagulant and / or adsorbent. The coagulant and / or solidifying agent may be as described in reference to the first embodiment above. The coagulant and / or solidifying agent may help to coagulate contaminants, making them easier to separate in the centrifuge.

[0091] The pretreatment unit may therefore include a flocculator device, such as a static or hydraulic flocculator device, in which the aggregation of contaminants occurs without any moving parts.

[0092] In an embodiment of the second aspect, the system further comprises a filter, such as a membrane filter, which is positioned downstream of the centrifuge to further purify the clean phase from the centrifuge.

[0093] In a second embodiment, the system further comprises an exhaust gas recirculation (EGR) unit arranged to purify exhaust gas from the engine and thereby produce contaminated purified water, the system further arranged to transport the contaminated purified water from the EGR unit to the centrifugal separator.

[0094] As described in relation to the first embodiment above, such an EGR unit may also be part of an EGR system for recirculating exhaust gas back to a marine engine. The EGR unit may be used to purify and cool the exhaust gas before it is introduced into the engine. The EGR unit may comprise an EGR cooling unit, in which the exhaust gas is cooled using a purifying fluid. The contaminated purifying fluid may therefore be formed from the EGR cooling unit. The system may further comprise a buffer tank from which the contaminated purifying fluid from the EGR unit is recovered and recirculated back to the EGR unit. Furthermore, the system may comprise an EGR drain tank, in which a portion of the contaminated cooling water is discharged for purification and subsequent disposal, for example, offshore. An injection unit may therefore be located directly in the EGR drain tank or in a recirculation system with an EGR drain tank but without a centrifuge, for the purpose of adding a solid porous adsorbent to the contaminated purifying fluid in the EGR drain tank, as described above.

[0095] In a second embodiment, the system further comprises a SOx scrubber arranged to purify exhaust gas from an engine and thereby produce contaminated purified water, the system further arranged to transport the contaminated purified water from the SOx scrubber to a centrifuge.

[0096] A SOx scrubber can be a so-called closed-loop scrubber that washes sulfur oxides and parts from exhaust gas using a circulating scrubber fluid containing fresh or seawater in combination with an alkalizing agent such as sodium hydroxide (NaOH) or magnesium hydroxide (Mg(OH)2). In such a scrubber, the amount of hydrated sulfites, sulfates, and parts in the circulating cleansing fluid gradually increases. The contaminated cleansing fluid may be continuously purified and sent back to the SOx scrubber.

[0097] The system may include a circulation tank, and the purified liquid may be recirculated to the SOx scrubber via the circulation tank. The system may be configured to transport a portion of the contaminated purified liquid in the circulation tank to a centrifuge and then back to the circulation tank. Therefore, a transport means such as a pump may be used to transport the contaminated purified liquid from the circulation tank to the centrifuge.

[0098] This system may also be configured to release a portion of the clean phase from the centrifuge overboard or into a tank for later disposal, meaning that not all of the clean phase is returned to the circulation tank. [Brief explanation of the drawing]

[0099] [Figure 1] A schematic diagram of one embodiment of the system of the present invention for purifying contaminated cleanup liquid from an EGR unit is shown. [Figure 2] A schematic diagram of another embodiment of the system of the present invention for purifying contaminated cleanup liquid from an EGR unit is shown. [Figure 3] A schematic diagram of another embodiment of the system of the present invention for purifying contaminated cleanup liquid from a SOx scrubber is shown. [Figure 4] A schematic diagram of a centrifuge that may be used in the system of this disclosure is shown. [Figure 5] The processing steps of the method of this disclosure are schematically illustrated. [Modes for carrying out the invention]

[0100] The methods and systems relating to this disclosure will be further illustrated by the following description with reference to the attached drawings.

[0101] Figure 1 shows a schematic diagram of one embodiment of System 1 for purifying contaminated purifying fluid. In this example, the contaminated purifying fluid is a marine exhaust gas purifying fluid, such as water, and is generated from an onboard exhaust gas recirculation (EGR) unit 20. The EGR unit 20 may also be part of a larger EGR system for recirculating exhaust gas back to the ship's engines. In the EGR unit, purifying fluid is used to cool and reduce contaminants in the exhaust gas being transported through the EGR unit 20 (as indicated by the thick arrows), thus generating contaminated purifying fluid. The contaminated purifying fluid is circulated between the EGR unit 20 and a buffer tank 21 via piping 30 and 31. The buffer tank 21 is connected to an EGR drain tank 22, for example, via an overflow outlet 32, so that the contaminated purifying fluid in the EGR drain tank 22 is not introduced into the EGR unit 20.

[0102] The contaminated purifying liquid in the EGR drain tank is transported to the centrifuge 2 via piping 33 and 34 using a supply pump 25. The centrifuge is positioned to separate the contaminated phase and the clean phase from the contaminated purifying liquid. The clean phase, which contains the thus purified purifying liquid, is continuously discharged to the outlet pipe 35 through a single liquid outlet, while the contaminated phase, which contains contaminated particles and oil, is intermittently discharged to the sludge tank 18.

[0103] A pretreatment unit 23 is also installed upstream of the centrifuge 2, and a feed pump 25 is positioned to transport the contaminated purified liquid to the centrifuge 2 via the pretreatment unit 23. The pretreatment unit 23 may also be a coagulant device and may further include a supply unit 24 for injecting a certain amount of coagulant and / or solidifying agent into the contaminated purified liquid to be purified in the separator 2. The supply unit 24 may contain the actual coagulant and / or solidifying agent to be added. The addition of the coagulant and / or solidifying agent increases the separation capacity of contaminants in the centrifuge 2.

[0104] The purified liquid from the outlet pipe 35 may be sent overboard or to a tank for later disposal via pipe 37, or returned to the EGR drain tank via pipe 36. This is controlled by valve means 27. Thus, the purified liquid may be mixed with the contaminated liquid in the EGR drain tank for further purification in a centrifuge. The liquid leaving system 1 via pipe 37 is, however, discharged from system 1.

[0105] As illustrated in Figure 1, System 1 includes an injection unit 26 equipped with a solid porous adsorbent. This unit is located upstream of the centrifuge 2 and is used for adding the solid porous adsorbent to the contaminated cleanup liquid. In the example illustrated in Figure 1, the injection unit 26 is positioned to add the solid porous adsorbent to the EGR drain tank 22, as indicated by arrow 38. To facilitate the mixing and adsorption of, for example, oil in the contaminated cleanup liquid to the adsorbent, the EGR drain tank 22 is equipped with a stirring means 45 for stirring the contaminated cleanup liquid within the EGR drain tank 22.

[0106] As mentioned above, the solid porous adsorbent may be activated carbon.

[0107] Furthermore, as indicated by the dotted arrow 39, a solid porous adsorbent may be added to the buffer tank 21 as a supplement or alternative.

[0108] Figure 2 shows a schematic diagram of one embodiment of System 1 for purifying contaminated liquid. In this example, the contaminated liquid is also a water-like marine exhaust gas purification liquid, originating from an onboard exhaust gas recirculation (EGR) unit 20. System 1 has the same parts and functions as described with respect to Figure 1 above, with the exception that System 1 further comprises a recirculation system 46 arranged to recirculate the contaminated liquid in the drain tank 22 before it is transported to the centrifuge 2. Thus, downstream of the feed pump 25, there is a valve means 40 arranged to direct the contaminated liquid in the EGR drain tank to a return conduit 36 ​​located between the centrifuge 2 and the EGR drain tank 22. Thus, by adjusting valves 40 and 41, a recirculation system 46 may be formed to recirculate the contaminated liquid using the feed pump 25. When recirculated, the contaminated liquid is transported through piping 33, 42 and 43. In such a configuration, an injection unit is arranged to add a solid porous adsorbent to the recirculation system 46. Therefore, the contaminants are mixed with the adsorbent during recirculation and transport in the recirculation system 46 during a time interval before the contaminant purification liquid, to which the adsorbent has been added using valve 40, is directed to the centrifuge 2 via pretreatment unit 23. As shown by arrow 38 in Figure 2, the injection unit 26 is positioned to add the adsorbent to the contaminant purification liquid downstream of the feed pump 25. However, alternatively, the injection unit 26 may be positioned upstream of the feed pump 25 in the recirculation system 46 to add the adsorbent to the contaminant purification liquid, such as between the EGR drain tank and the feed pump 25.

[0109] Figure 3 shows a schematic diagram of one embodiment of System 1 for purifying contaminated cleanup fluid. In this example, the contaminated cleanup fluid is a water-like marine exhaust gas cleanup fluid, which originates from a SOx scrubber 50 positioned to purify exhaust gases from an engine on board a ship.

[0110] The exhaust gas is therefore sent to be washed in the scrubber 50 with a purifying liquid, which may absorb contaminants from the exhaust gas and thus generate a contaminated purifying liquid. The scrubber 50 further comprises an electrostatic precipitator 51 to further increase the absorption of contaminants into the purifying liquid. The contaminated purifying liquid from the scrubber 50 is transported via piping 61 to a circulation tank 52, and the purifying liquid from the circulation tank 52 is circulated back to the scrubber via pipe 62 and to the dust collector 51 via pipe 63. Before being introduced into the scrubber and / or dust collector, an alkalizing agent such as sodium hydroxide (NaOH) or sodium carbonate (Na2CO3) is added to the purifying liquid using an injection unit 53.

[0111] The contents of the circulation tank 52, therefore containing contaminated purification liquid, are purified by the centrifuge 2 and returned to the circulation tank via the return pipeline 36, or discharged from the system via pipe 37 to a tank for offshore disposal or for later disposal.

[0112] The contaminated purifying liquid in the circulation tank 52 is transported to the centrifuge 2 via piping 33 and 34 using a supply pump 25. As in the system described with respect to Figures 1 and 2, the centrifuge 2 is positioned to separate the contaminated phase and the clean phase from the contaminated purifying liquid. The clean phase, which contains the thus purified purifying liquid, is continuously discharged to the outlet pipe 35 through a single liquid outlet, while the contaminated phase, which contains contaminated particles and oil, is intermittently discharged to the sludge tank 18.

[0113] A pretreatment unit 23 is also installed upstream of the centrifuge 2, and a feed pump 25 is positioned to transport the contaminated purified liquid to the centrifuge 2 via the pretreatment unit 23. The pretreatment unit 23 may also be a coagulant device and may further include a supply unit 24 for injecting a certain amount of coagulant and / or solidifying agent into the contaminated purified liquid to be purified in the separator 2. The supply unit 24 may contain the actual coagulant and / or solidifying agent to be added. The addition of the coagulant and / or solidifying agent increases the separation capacity of contaminants in the centrifuge 2.

[0114] As described above, the purified liquid from the outlet pipe 35 may be sent overboard or to a tank for later disposal via pipe 37, or returned to the circulation tank 52 via return pipe 36. This is controlled by valve means 27. A centrifuge 2 may be used to continuously purify the circulating liquid used in the scrubber 50. The liquid leaving system 1 via pipe 37 is, however, discharged from system 1.

[0115] As illustrated in Figure 3, System 1 includes an injection unit 26 equipped with a solid porous adsorbent. This unit is located upstream of the centrifuge 2 and is used to add the solid porous adsorbent to the contaminated cleanup liquid. In the example illustrated in Figure 3, the injection unit 26 is positioned to add the solid porous adsorbent to the circulation tank 52, as indicated by arrow 38. Since the contents of the circulation tank are circulated to the scrubber 50 and the centrifuge 2, no further agitation means may be required for the tank 52.

[0116] Figure 4 illustrates further details of a part of the centrifuge 2 that may be used in System 1 as illustrated in Figures 1 to 3.

[0117] The centrifuge 2 comprises a rotating part arranged for rotation around a rotation axis (X), a centrifugal bowl 3, and a spindle 4. The spindle 4 is supported by the centrifuge's fixed frame 5 in lower bearings 6 and upper bearings 7.

[0118] The centrifugal bowl 3 forms a separation chamber 8 within itself during operation, in which, for example, the centrifugation of the contaminated cleanup liquid takes place.

[0119] The separation chamber 8 is provided with a stack of truncated cone separation disks 9 to achieve effective separation of the liquid. The stack of truncated cone separation disks 9 is an example of a surface-enlarged insert. These disks 9 are centrally and coaxially fitted with the centrifugal bowl 3 and have holes that form channels 10 for axial flow of the liquid when the separation disks 9 are fitted into the centrifugal bowl 3.

[0120] The contaminated cleanup liquid to be separated is fed in from above through a fixed inlet pipe 11 that extends downward within the centrifugal bowl 3.

[0121] The centrifugal bowl 3 has a liquid light phase outlet 12 extending from it for the clean liquid phase separated from the contaminated purifying fluid. The liquid light phase outlet 12 extends through the frame 5 at the top of the separator. In this example, the separator 2 has only one liquid outlet 12, but the separator 2 may also have additional liquid outlets for liquid phases of densities other than the density of the liquid taken out through outlet 12. This depends on the liquid material to be processed. In such cases, any liquid of a higher density may instead be pushed out through an additional liquid outlet (not shown) located at a radial distance greater than the radial level of outlet 12. As an example, if oil is to be separated from the contaminated scrubber fluid as a separate liquid phase, an additional liquid outlet may be utilized.

[0122] The centrifugal bowl 3 is provided with a pair of radial sludge outlets 13 on its outer circumference, in the form of intermittently openable outlets for the release of denser components, such as sludge or other solids in the liquid. Contaminants in the form of particles and oil adhering to the particles may therefore be discharged from the radially outer portion of the separation chamber 8 into the space around the centrifugal bowl 3.

[0123] The centrifuge 2 is further provided with a drive motor 14. This motor 14 may be an electric motor, for example, arranged to transmit drive torque to the spindle 4 and therefore to the centrifugal bowl 3 and rotor 3. Alternatively, the drive motor 14 may be connected to the spindle 4 by a transmission means such as a drive belt.

[0124] During the operation of the separator in Figure 3, the centrifugal bowl 3 is rotated by torque transmitted from the drive motor 14 to the spindle 4. The contaminated purifying liquid to be separated is introduced into the separation space 8 via the fixed inlet pipe 11, for example, when the rotor is already running at its operating speed. The contaminated purifying liquid may therefore be continuously introduced into the rotor 3.

[0125] The contaminant phase, containing particles and oil agglomerated onto the particles, moves radially outward between the separation disks, while the clean phase, i.e., the purified liquid, moves radially inward between the separation disks and is expelled through outlet 12. The contaminant phase, containing particles and oil, accumulates around the separation chamber 8 and is intermittently removed from the separation space by the open sludge outlet 13, after which the contaminant phase is discharged from the separation space using centrifugal force.

[0126] Figure 5 illustrates various method steps of Method 100 for purifying a contaminated wastewater, where the wastewater is a contaminated ocean exhaust gas wastewater. Method 100 includes a) step 101 of preparing the wastewater, b) step 102 of adding a solid porous adsorbent to the wastewater, and c) step 103 of reacting the adsorbent with the pollutants in the wastewater. The method further includes step 106 of adding a coagulant and / or solidifying agent to the wastewater before step 104 of separating the wastewater using a centrifuge. Method 100 further includes e) step 105 of discharging the clean liquid phase and the pollutant phase from the centrifuge.

[0127] The present invention is not limited to the disclosed embodiments and may be modified and altered within the scope of the claims described below. The present invention is not limited to the type of separator illustrated in the figures. The term “centrifuge” also includes centrifuges in which the rotating shaft is oriented substantially horizontally, and separators having two or more liquid outlets.

[0128] Experimental example The oil adsorption efficiency of powdered activated carbon was tested. Lubricating oil was added to desalination laboratory water to a concentration of 250 mg / l. The lubricating oil was 905 kg / m³. 3 It had the following density. Two different types of powdered activated carbon were used: Sample 1 is 900m 2 It had a surface area of ​​50 μm per g and an average diameter of 50 μm. Microscopic examination revealed that the maximum particle size was 35 μm. Sample 2 is 550m2 The particles had a surface area of ​​25 μm per gram and an average diameter of 25 μm. Microscopic examination revealed that the maximum particle size was 180 μm.

[0129] A total of 16 tests were performed using various injection rates for two different samples. The amount of oil in water was measured in the range of C6 to C40 using the standard M-0153 GC-FID.

[0130] All samples showed good oil removal efficiency in the range of 65-90%. Therefore, laboratory tests clearly demonstrated that activated carbon samples can remove oil from water samples. This proves that oil in contaminated purified water can be adsorbed onto activated carbon and thus more easily separated by centrifuge. [Explanation of symbols]

[0131] 1. System for purifying contaminated liquid 2. Centrifugal separator 3 Centrifugal bowl 4 spindles 5 Fixed frame 6 Lower bearing 7 Upper bearing 8 Separation Chambers 9 Separable disk 10 channels 11 Fixed inlet pipe 12 Liquid light phase outlet 13 Radial sludge outlet 14 Drive motor 18 Sludge Tank 20. Exhaust Gas Recirculation (EGR) Unit 21 Buffer Tank 22 EGR drain tank 23 Pre-processing unit 24 supply units 25. Liquid supply pump 26 Injection Unit 27 Valve mechanism 30, 31, 33, 34 Piping 32 Overflow Outlet 35 Outlet pipe 36, 37 tube 38 Arrows 39. Dotted arrow 40 Valve mechanism 41 valves 42, 43 Piping 45 Stirring means 46 Recirculation System 50 SOx Scrubber 51 Electrostatic precipitator 52 Circulation Tank 53 Injection Unit 61 Piping 62, 63 tube

Claims

1. A method (100) for purifying a contaminated purification liquid, wherein the contaminated purification liquid is a contaminated marine exhaust gas purification liquid. a) Step (101) of preparing the contaminated cleansing liquid, b) The step (102) of adding a solid porous adsorbent to the contaminated cleanup liquid, c) A step (103) in which the adsorbent reacts with the contaminants in the contaminated cleanup liquid, d) A step (104) of separating the contaminated cleanup liquid using a centrifuge, e) Step (105) of discharging the clean liquid phase and the contaminant phase from the centrifuge, Methods that include...

2. The method according to claim 1 (100), wherein step c) is performed while the contaminated purification liquid is being stirred.

3. The method according to claim 2 (100), wherein the addition in step b) is made to the tank containing the contaminated purified water.

4. The method according to claim 2 (100), wherein the addition in step b) is made to a piping system (46) through which the contaminated purified water is transported.

5. The method according to any one of claims 1 to 4 (100), further comprising the step (106) of adding a coagulant and / or a coagulant to the contaminated cleanup liquid before step d).

6. The method according to any one of claims 1 to 5 (100), wherein the separation in step d) produces a single contaminant phase and a single liquid phase, and the single liquid phase is discharged as the clean liquid phase in step e).

7. The method according to any one of claims 1 to 6 (100), wherein the contaminated cleanup liquid prepared in step a) is derived from a recirculated cleanup liquid used in an exhaust gas recirculation (EGR) unit for marine applications.

8. The method according to any one of claims 1 to 6 (100), wherein the contaminated cleanup liquid prepared in step a) is derived from the recirculated cleanup liquid used in the SOx scrubber.

9. The method according to any one of claims 1 to 8 (100), wherein the solid porous adsorbent used is selected from the group consisting of activated carbon, zeolite, iron oxide coated sand, silica gel, nanoadsorbent, graphene-based adsorbent, and natural adsorbent.

10. The method according to any one of claims 1 to 9 (100), further comprising step f) returning the clean liquid phase, or at least a portion of the clean liquid phase, to the upstream position of the centrifuge.

11. The method according to any one of claims 1 to 10 (100), wherein the solid porous adsorbent is added to the contaminated cleanup liquid in step b), has an average particle size of less than 1 mm, and is added to the contaminated cleanup liquid at a concentration of less than 2 g / L.

12. A system (1) for purifying a contaminated liquid, wherein the contaminated liquid is a marine exhaust gas purification liquid. - A centrifuge (2) arranged to separate at least one contaminated phase and a clean phase from the contaminated purification liquid, - An injection unit (26) equipped with a solid porous adsorbent, which is located upstream of the centrifugal separator for adding the solid porous adsorbent to the contaminated purification liquid, - Transport means (25) for transporting the contaminated cleanup liquid to the centrifuge (2) to which the adsorbent has been added. A system (1) comprising:

13. The system (1) according to claim 12, further comprising tanks (22, 52) capable of transporting the contaminated purification liquid to the centrifugal separator (2).

14. The system (1) according to claim 13, wherein the injection unit (26) is arranged to add the solid porous adsorbent to the tanks (22, 52), and the tanks are provided with stirring means (45) for stirring the contaminated cleanup liquid in the tanks (22, 52).

15. The system (1) according to claim 13, further comprising a recirculation system (46) arranged to recirculate the contaminated clean liquid in the tanks (22, 52) before transport to the centrifuge, wherein the injection unit is arranged to add the solid porous adsorbent to the recirculation system (46).

16. The system (1) according to any one of claims 12 to 15, further comprising an exhaust gas recirculation (EGR) unit (20) arranged to purify exhaust gas from an engine and thereby produce contaminated purified water, wherein the system (1) is further arranged to transport the contaminated purified water from the EGR unit (20) to the centrifugal separator (2).

17. The system (1) according to any one of claims 12 to 15, further comprising a SOx scrubber (50) arranged to purify exhaust gas from an engine and thereby produce contaminated purified water, wherein the system (1) is further arranged to transport the contaminated purified water from the SOx scrubber (50) to the centrifugal separator (2).

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