Integrated process for removing carbon dioxide from vessel or floating vessel at sea using rotating filling device

Abstract

A method for scrubbing flue gas comprising: providing a rotating packed bed device on a vessel or marine vessel generating flue gas; an absorbent is fed together with the flue gas into the rotating packed bed to remove carbon dioxide.

Description

Technical Field

[0001] The present invention relates to an improved method and system for removing carbon dioxide from flue gases on board a ship or other floating marine vessel using a rotating packed bed apparatus. Background Art

[0002] Shipping is one of the most difficult industries to decarbonize, as the need to install emission reduction treatment equipment on ships can pose challenges due to the movement of ships, limited floor space, weight and other restrictions. Existing traditional technologies for CO2 reduction in land-based environments, such as packed towers, are not ideal solutions for offshore environments due to their large size. Due to the large size of packed towers, it may be necessary to increase the size of the ship and strengthen the packed tower structure to accommodate the movement forces encountered in the marine environment.

[0003] Rotating packed bed technology (RPB) offers advantages for marine environments such as low height, light weight and small footprint, lower absorbent inventory, and lower CO2 capture costs. In addition, RPB technology has operability advantages because it relies on centrifugal force to enhance the mass transfer process and is therefore insensitive to motion and direction, making RPB technology suitable for marine applications. RPB turndown is 10%, making RPB technology suitable for different engine loads.

[0004] The marine environment is unstable, and conventional scrubbers are susceptible to blow-through and erratic performance due to wave action, wind, and other forces that can cause motion. Since the motion of the vessel is erratic and often unpredictable, it is difficult to maintain effective contact between the flue gas and the liquid or solid used to scrub the flue gas. As a result, conventional flue gas scrubbing systems need to be over-designed, which increases one or more of cost, weight, height, and footprint.

[0005] Previous flue gas scrubbing systems, such as those using fluidized bed or packed bed spray scrubbers, were very large and heavy. Previous systems were also difficult to retrofit onto existing vessels.

[0006] There is a need for improved methods and systems for removing pollutants including carbon dioxide from flue gases onboard ships. There is a need for improved systems for more effectively removing flue gas pollutants.

[0007] Previous attempts to remove pollutants from flue gases have been directed to SOx removal on ships, an open system that utilizes seawater for discharge back to the ocean. Amines or other commercially produced chemical solvents are hazardous and cannot be discharged into the sea. Further attempts to remove CO2 from the feed gas have been directed to natural gas, etc., which is available at much higher pressures than the flue gases. A system or process for capturing CO2 that avoids the discharge of hazardous chemical solvents into the ocean and addresses the environmental pressures of flue gases is needed and is described herein. Summary of the invention

[0008] An embodiment of the present invention is a closed loop process for removing CO2 from flue gases which includes using a Venturi cooler to process the hot flue gases from a vessel and cool them down.

[0009] Another embodiment is to feed the cooled flue gas into one or more rotating packed bed (RPB) units and contact it with a scrubbing liquid that selectively captures CO2, such as conventional amines (MEA, DEA and MDEA), higher amines containing activated MDEA, a combination of piperazine and MDEA, ionic liquids or switchable polarity fluids (SPS).

[0010] Another embodiment is an integrated system for scrubbing liquid containing two tanks, one for containing fresh liquid and the other for collecting the waste fluid reacted with CO2.

[0011] Another embodiment is one or more RPB devices located in the hull or chimney of a marine vessel, comprising a rotating shaft and a porous media, and configured to mix the flue gas with a CO2 capture liquid outwardly at a sufficient gas / liquid ratio to reduce the CO2 concentration in the flue gas to a desired level. The outward flue gas / liquid feed to the RPB may be co-current and will allow a pressure increase of up to 50 kPa from the internal area of ​​the RPB to the external area and overcome the pressure limitations of the flue gas.

[0012] Another embodiment of the present invention is to add another RPB to regenerate the waste fluid on board and store the desorbed CO2 in tanks on board. Another option is to regenerate the waste fluid at an onshore facility during port stays. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 An embodiment of the invention is depicted showing the use of energy recovered from liquid expansion and pressure reduction to drive a rotating packed bed absorber. DETAILED DESCRIPTION

[0014] A process and closed system for removing CO2 from flue gas produced by ships or marine vessels without the use of seawater is described herein. The process and system utilizes CO2 capture from one or more RPB units on board the vessel in combination with a chemical reaction between CO2 and amines or advanced solvents such as ionic liquids or switchable polarity solvents (SPS).

[0015] A "ship" is a large sailing vessel that travels in the world's oceans and other sufficiently deep waterways by means of one or more engines emitting fumes or gases containing CO2, carrying passengers or cargo, or supporting specialized missions such as defense, research and fishing. A "sea vessel" is a vessel that travels in the ocean or seawater.

[0016] "Flue gas" is the gas emitted into the atmosphere through a flue, which is a pipe or channel used to carry exhaust gases from a fireplace, engine, oven, furnace, boiler, or steam generator. For example, flue gas may refer to the combustion exhaust produced by an engine. "Total suspended solids" (TSS) is the dry weight of particles captured by a filter. Total suspended solids is a water quality parameter used, for example, to assess the quality of effluent after treatment at a sewage treatment plant. TSS is listed as a conventional pollutant in the Clean Water Act of the United States. "Heavy fuel oil" (HFO) describes a fuel used to produce motion and / or to produce heat that has a particularly high viscosity and density. Heavy fuel oil may be defined as having a density greater than 900 kg / m3 at 15°C, or a kinematic viscosity greater than 180 mm2 / s at 50°C. Heavy fuel oils may contain a large amount of heavy molecules, such as long-chain hydrocarbons and aromatics with long side chains, and they may be black in color.

[0017] "Centrifugal force" is an inertial force acting away from the axis of rotation, which appears to act on all objects from a rotating reference frame. The radial force generated by a spinning rotor is expressed relative to the earth's gravity and is therefore called relative centrifugal force (RCF) or "g-force". The g-force acting on a particle is exponentially related to the rotational speed, defined as the number of revolutions per minute (RPM). The function between these two parameters follows the formula: RCF = 1.2r(RPM / 1000)(RPM / 1000), where r is in millimeters.

[0018] "Turndown" refers to the width of the operating range of a device and is defined as the ratio of the maximum operating capacity to the minimum operating capacity. For example, a device with a maximum output of 10 units and a minimum output of 2 units has a turndown ratio of 5.

[0019] "Anti-scalants" are a class of chemicals designed to inhibit the formation and precipitation of scale-forming crystalline mineral salts. In the context of the present invention, sufficient centrifugal force may be an RCF sufficient to promote good gas-liquid contact and prevent flue gas 15 blow-through during operation of the rotating packed bed apparatus 4. In one embodiment, the RCF may be greater than 1, such as greater than 4 up to 10,000. Blow-through may be caused by the motion of a ship or floating vessel at sea and is difficult to prevent using conventional flue gas 15 scrubbers.

[0020] The removal of CO2 from flue gas begins by feeding the flue gas into a venturi quencher to treat the hot flue gas from the ship and cool it down, and then the cooled flue gas is fed into the RPB device and contacted with a scrubbing liquid (or also referred to herein as a liquid absorbent). The scrubbing liquid includes a CO2 capture liquid known to those skilled in the art, preferably selected from conventional amines (MEA, DEA and MDEA), higher amines (activated MDEA, a combination of piperazine and MDEA), aqueous potassium carbonate (alone or promoted with piperazine), ionic liquids or switchable polarity fluids (SPS). The process as described herein can remove up to 92% of CO2 from flue gas, and when multiple RPBs are implemented, up to 100% of CO2 can be removed.

[0021] Table 1 below shows examples of good CO 2 removal at different flow rates of CO 2 and methylethanolamine (MEA).

[0022]

[0023] An embodiment of the present invention is an integrated system for scrubbing liquid that includes two tanks, one for containing fresh liquid and the other to collect the waste fluid that reacts with CO2.

[0024] Another embodiment is to regenerate the waste fluid by feeding one or more RPBs and store the desorbed CO2 in a tank on a ship or on a vessel, or regenerate the waste fluid at an onshore facility during a port stop. Regeneration includes applying a temperature above 212°F to the waste fluid to release CO2. The scrubbing liquid does not contain or partially does not contain CO2, and is able to capture CO2 again in the absorption cycle. This regeneration can be carried out in any convenient way and a regenerator can be used to regenerate the impurity-rich liquid solution. The regenerator is optionally and operably connected to, for example, a flash tank and a rotating packed bed absorber. In this way, the impurity-rich liquid can be transported to a second (or more) rotating packed bed regenerator for regeneration. The specific equipment of the regenerator may vary depending on the specific process, other equipment and available space. For example, the regenerator may include, for example, a heater (such as a reboiler and a condenser), one or more additional rotating packed bed regenerators (with one or more rotatable filling rings), or even some combination thereof. If desired, the heating or reboiler unit can be located outside the rotating packed bed chamber, or partially or fully integrated, that is, integrated in the rotating packed bed chamber. In some embodiments, the regenerator may include a packed column.

[0025] Another embodiment is a RPB device located in the hull or chimney of a marine vessel, which includes a rotating shaft and a porous media, and is configured to mix the flue gas with the CO2 capture liquid outwardly at a sufficient gas / liquid ratio to reduce the CO2 concentration in the flue gas to a desired level. The co-current outward flue gas / liquid feed of the RPB will allow a pressure increase of up to 50 kPa from the internal area of ​​the RPB to the external area and overcome the pressure limitations of the flue gas. Additional pressure increases can be achieved by increasing the rotational speed of the RPB to overcome the pressure limitations of the flue gas, such as a pressure increase of greater than 50 kPa. Countercurrent mode is also an embodiment of the present invention. Cocurrent and countercurrent modes are described in 11,491,441, which is incorporated herein by reference, where the fluid used is not seawater.

[0026] In the context of the present invention, sufficient centrifugal force may be an RCF sufficient to promote good gas-liquid contact and prevent blow-through of flue gas 15 during operation of the rotating packed bed apparatus 4. In one embodiment, the RCF may be greater than 1, such as greater than 4 up to 10,000. Blow-through may be caused by the movement of a ship or floating vessel at sea and is difficult to prevent using conventional flue gas 15 scrubbers. In one embodiment, sufficient centrifugal force provides a liquid holdup of less than 1 wt%, such as 0.01 to 0.50 wt%, in the rotating packed bed apparatus 4. Low liquid holdup reduces weight and effectively uses the porous material in the rotating packed bed apparatus 4. For example, in one embodiment, the rotating packed bed apparatus 4 includes one or more rotatable packing rings 4A of porous material that operate under sufficient centrifugal force to provide a liquid holdup of 0.01 to 0.5 wt% in the rotating packed bed apparatus 4.

[0027] In one embodiment, the rotating packed bed apparatus 4 comprises a porous material having a high surface area per unit volume, such as greater than 150 m2 / m3, or about 200 to about 6,000 m2 / m3. In one embodiment, the rotating packed bed apparatus 4 comprises one or more rotatable packing rings 4A comprising a porous material having a high surface area per unit volume. In one embodiment, the rotating packed bed apparatus 4 comprises one or more rotatable packing rings 4A comprising a porous material.

[0028] A rotating packed bed apparatus as described in WO 2018 / 229589 A1, US 11,491,441 (incorporated herein by reference) can be used with the systems and processes for removing CO2 from flue gas described herein.

[0029] An embodiment of the present invention is a RPB device located in the hull or chimney of a marine vessel, comprising a rotating shaft and a porous media, and configured to mix the flue gas with a CO2 capture liquid outwardly at a sufficient gas / liquid ratio to reduce the CO2 concentration in the flue gas to a desired level. The co-current outward flue gas / liquid feed of the RPB will allow a pressure increase of up to 50 kPa from the inner area of ​​the RPB to the outer area and overcome the pressure limitations of the flue gas. A preferred embodiment is to co-feed the gas and liquid through the annular portion of the RPB to overcome the pressure drop of the flue gas.

[0030] refer to Figure 1 Based on the exemplary embodiments in and the description of the internal and external regions of the RPB in US 491,441, the method disclosed herein can utilize a system as shown in the figure, including a rotating packed bed device. In this embodiment, the rotating packed bed device includes one or more rotatable packing rings disposed in a shell. The one or more rotatable packing rings may generally have the shape of a thick cylindrical disk having a hollow central axial portion or space, also referred to herein as an internal region. The rotatable packing rings surrounding the internal region define the internal region. The rotatable packing rings are enclosed in a space inside the shell. This space is the external region in the rotating packed bed device, Figure 1 In addition, the system is equipped with a Venturi quencher ( Figure 1 The RPB device is not labeled in the figure, for receiving hot flue gas from the ship and cooling it, and then feeding the cooled flue gas into the RPB device and contacting it with a scrubbing liquid as described herein. In one embodiment, a pressure increase is formed between an inner region in the rotating packed bed device 4 and an outer region in the rotating packed bed device. The pressure increase can be 0 kPa or greater, such as greater than 2 or 3 kPa, for example 0 kPa to 50 kPa. This pressure increase can act as a blower and can help push the low-pressure flue gas 15 from the engine through the rotating packed bed device 4. The pressure increase can significantly reduce or prevent unwanted back pressure on the engine on a ship or floating ship at sea. This may be very desirable when processing low-pressure flue gas 15. In one embodiment, the maximum allowable back pressure that a ship engine can withstand is 981 Pa, and the rotating packed bed device 4 is configured to prevent the ship engine from generating back pressure.

[0031] The high gravity generated by the centrifugal force of the rotatable filling ring 4A allows the use of unique packing materials with very high surface areas and fine pore diameters. The rotatable filling ring 4A can be made of a variety of suitable materials, including, for example, metal foams, plastics, composite materials, stainless steel, titanium, super duplex stainless steel alloys, metal or non-metallic wire mesh, knitted fabrics, and porous materials including glass fibers. In one embodiment, the rotatable filling ring 4A includes a porous material having a surface area per unit volume (specific surface area) of about 200 to about 6,000 m2 / m 3 In one embodiment, the rotatable filling ring 4A comprises a porous material, which is a metal foam, a metal mesh, a glass fiber, a polymer or a composite thereof. In one embodiment, the porous material has an average pore size of 100 to 10,000 microns. In one embodiment, the porous material is a metal foam having a porosity of at least about 90% and an average pore size of 250 to 2500 microns. In one embodiment, the metal foam is Metal foam (RMF). RECEMAT is a registered trademark of RECEMAT BV, headquartered in the Netherlands. RMF is one of the metal foams available on the market, and it is an open-cell polyurethane foam metallized using an electrodeposition technique with excellent control over pore size. In one embodiment, RMF has a nickel microstructure, a nickel-chromium (NC) microstructure, or a nickel-chromium extra foam (NCX) microstructure. In one embodiment, the metal foam has a thickness of 1.6 to 20 mm and a pore size of 0.4 to 2.3 mm. In one embodiment, the metal foam has the identification of NCX0610, NCX1116, NCX1723, NCX2733, or NCX4753. Table 2 summarizes the typical properties of these types of metal foams.

[0032] Table 2

[0033]

[0034] The average composition refers to the composition of the outer surface of the foam metal.

[0035] The above-described processes and systems may be advantageous for a number of independent reasons. For example, when an integrated process and system with a rotating packed bed is used for absorption and / or regeneration, capital costs can generally be reduced and equipment weight and / or footprint (especially in the vertical direction) can be reduced due to the compact nature of the rotating packed bed. In addition, the processes and systems generally have improved safety due to reduced liquid inventory, improved operability due to reduced potential foaming, and generally have a higher turndown ratio. In addition, the basic insensitivity of the rotating packed bed to motion may be advantageous for ships and sea vessels that generate flue gases. Another advantage may be transportation and installation in remote areas. Typically, amine loading is limited in conventional ships due to corrosion issues. However, due to the more compact nature of the rotating packed bed, which allows the use of more expensive materials, such as alloys, a richer, i.e., more concentrated, increased amine loading can be used, which can reduce circulation rates and, in turn, can reduce operating costs.

Claims

1. A method for removing carbon dioxide from flue gas on a ship or marine vessel generating the flue gas, comprising: (a) feeding the flue gas containing CO2 into a venturi quench cooler to treat the hot flue gas from the ship and cool it, (b) feeding the cooled flue gas into a rotating packed bed (RPB) device, and (c) contacting with a scrubbing liquid to form a waste stream containing bound CO2.

2. The method of claim 1, wherein the rotating packed bed apparatus comprises one or more rotatable packed rings, wherein the one or more rotatable packed rings define an inner region and an outer region in the rotating packed bed apparatus.

3. The method of claim 2, wherein a pressure increase from an inner region in the rotating packed bed apparatus to an outer region in the rotating packed bed apparatus is 0 kPa to 50 kPa.

4. The method of claim 3, wherein the scrubbing liquid is selected from the group consisting of conventional amines (MEA, DEA and MDEA), higher amines (activated MDEA, a combination of piperazine and MDEA), aqueous potassium carbonate solution, ionic liquids or switchable polarity fluids.

5. The method of claim 1, wherein the spent fluid is regenerated by feeding one or more RPBs and the desorbed CO2 is stored in tanks on board a vessel or ship, or the spent fluid is regenerated at an onshore facility.

6. An integrated system for onboard scrubbing of marine exhaust gases on board a vessel, comprising: i) a hot exhaust gas inlet, the hot exhaust gas inlet feeding the marine exhaust gas from the engine on the vessel at a temperature higher than 180° C.; and b) the rotating packed bed device, the rotating packed bed device having: iii) a fixed gas distributor disposed along the periphery of the rotating packed bed device and connected to the venturi quench cooler, wherein the fixed gas distributor is configured to receive the cooled exhaust gas and evenly distribute the quenched marine exhaust gas along the periphery of the rotating packed bed device; and iv) a fixed liquid distributor having a plurality of liquid rings, said fixed liquid distributor being positioned in the center of said rotating packed bed device, wherein said plurality of liquid rings are equipped with nozzles which spray liquid absorbent as a co-feed with the cooled exhaust gas into the annular space of said rotating packed bed device.

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