Field of the Invention

The present invention relates to a pollution control apparatus suitable for use on seafaring vessels. The apparatus permits the capture, destruction and/or safe collection of pollutants generated by the engines of ships and other seafaring vessels. In particular, the apparatus permits the capture and safe collection of sulphur oxides (SOx), nitrous oxides (NOx) and particulates such as dust and soot or other carbonaceous materials.

Background of the Invention

Seafaring vessels, such as container ships, cruise ships and other military vessels and pleasure boats routinely generate dangerous and noxious by-products from the burning of fossil fuels in their engines that are considered severe pollutants of both air and sea. There is increased worldwide scrutiny of the shipping industry; in many territories legislation is in place or is being introduced to reduce, prevent or eliminate the emission of pollutants from seafaring vessels.

Many options to improve the situation, including the use of alternative fuels and the adoption of technologies used on land, have been tried on seafaring vessels, with varying degrees of success.

However, a practical and economic solution to the issue of pollution from seafaring vessels is still desired.

The pollution control technology most commonly used at sea is a wet scrubbing process whereby water, optionally together with chemical reactants, is sprayed into engine exhaust gases. The scrubber water absorbs SOx emissions and other particulate matter that would otherwise be emitted as part of the exhaust gas stream.

This process has the disadvantage of creating a by-product which comprises the scrubber water together with the pollutants. In practice it is commonplace to directly discharge this to the ocean, with it being suggested that dilution will mitigate the adverse effects of the pollutants. This is known as an “open loop” system. An alternative is a “closed loop” system where the polluted scrubber water is collected and treated on-board the vessel, before then being re-used to capture more pollutants. However, this is an expensive and complicated approach.

Wet scrubbing processes capture around 80% of the particulates generated by the engines. Unfortunately, it is the smallest particulates that evade capture by wet scrubbing and these fine particulates are the most dangerous to health. In addition, wet scrubbing methods do not address NOx emissions. NOx can be treated with a reactant in the presence of catalysts to render it harmless, but this process is not readily compatible with wet scrubbing processes. Wet scrubbing processes also often need to use equipment made from expensive grades of stainless steel to withstand the harsh chemical environment created within the process.

Ceramic filters, e.g. in form of filter candles, are used in many land-based industries for removal of particulate matter. They are one of the most efficient types of dust collectors available and can achieve collection efficiencies of more than 99% for particulates, including fine particulates. The filters can be made from various ceramic materials comprising ceramic fibres, e.g. alkali and alkaline earth silicates or aluminosilicates.

When catalytic ceramic filters are used, these processes can remove and eliminate SOx and NOx as well as particulates. Removal of 95% or more SOx and NOx can be achieved. These catalytic ceramic filters can operate at 200-450°C, preferably at around 300-350°C. These processes have the benefit of allowing cheaper materials to be used for the equipment, e.g. carbon steels may be used, because there are no harsh environments created.

Summary of the Invention

The present inventors have recognised that dry processes based on ceramic filters and catalytic ceramic filters encounter problems when used at sea, which has so far prevented adoption of this technology. This is because the filters are delicate and can be damaged by the vibration, movement, swell and roll experienced at sea.

The present inventors have therefore devised a new pollution control apparatus suitable for use on seafaring vessels. In this regard, in a first aspect the present invention provides a pollution control apparatus suitable for use on seafaring vessels, the apparatus comprising: an outer frame structure, comprising a first pair of parallel frame members and a second pair of parallel frame members, the first pair of parallel frame members being perpendicular to the second pair of parallel frame members; one or more supporting cage structure, each cage structure comprising (i) a plurality of elongate bars arranged parallel to one another and spaced about a central elongate axis and (ii) a plurality of reinforcement bands, with each band extending around the perimeter of the spaced arrangement of bars, wherein each cage structure extends parallel to the first pair of parallel frame members and is secured to the outer frame structure; and a plurality of elongate catalytic ceramic filter elements, each filter element comprising porous ceramic outer walls which define a hollow inner section, wherein catalyst is disposed within the hollow inner section and/or within the porous ceramic walls, wherein each filter element extends parallel to the first pair of parallel frame members and is secured to the outer frame structure, and wherein each filter element also extends parallel and adjacent to a cage structure and is supported thereby.

In use, the pollution control apparatus can be positioned such that the engine exhaust gas flows along the length of the catalytic ceramic filter elements.

The apparatus is beneficial in that it provides a structured support for the catalytic ceramic filter elements. This ensures that even when subjected to the vibration, movement, swell and roll experienced at sea, the filter elements are supported and are not damaged by erosion twisting or excessive torque force. The design is robust and reliable and enables the catalytic ceramic filter elements, which by themselves are delicate and prone to damage and failure, to be used at sea under the tough conditions that can be experienced there.

In particular, the combination of the outer frame structure and the supporting cage structures provides robust support for the catalytic ceramic filter elements whilst also ensuring that there is effective circulation of the engine exhaust gas around the catalytic ceramic filter elements. Therefore, the arrangement of the present invention ensures that the catalytic ceramic filter elements are not damaged or destroyed by the conditions encountered at sea, whilst achieving effective capture and safe collection of pollutants generated by the engines of ships or other seafaring vessels.

Advantageously, the apparatus allows the treatment of a multitude of pollutants generated by the engines of ships or other seafaring vessels to be captured. It is possible to remove particulates, SOx and NOx in a single step, with a single piece of equipment. This is economical when considering operating costs, by treating several pollutants at the same time.

The invention is also beneficial in that a range of different catalysts can readily be provided in the form of elongate catalytic ceramic filter elements. It is easy to swap in and swap out elongate catalytic ceramic filter elements from the apparatus and therefore to modify the catalyst that is present in the apparatus as needed. In particular, by the selection of a suitable catalyst the apparatus can be easily modified to handle pollutants and off gases created from the combustion of alternative fuels, such as ammonia, liquified natural gas, methane, methanol and high or low sulphur fuel oils. The invention is also able to offer maximum efficiencies of reduction of pollutants, via the selection of a suitable catalyst, and is highly suitable when two or more fuels are used to power a ship. Therefore, there is flexibility and the ability to ensure efficient pollutant removal regardless of the fuel or fuel mixture that is being used.

The apparatus is also valuable in that it can be that it can be fitted to a seafaring vessel in a much shorter time than a wet system. The apparatus is compact and can be configured in advance; it can then be quickly and easily fitted to the vessel so as to minimize delay and downtime. It is expensive to keep a ship or other seafaring vessel in dock and therefore this shorter fitting time is advantageous.

The apparatus permits the filtration equipment to be configured and arranged in a compact form, taking up a minimum of space on the vessel. In particular, due to being compact, the apparatus may be located within the funnel area. This is beneficial because the heat generated by the engine will in turn heat the filter elements that are located within the funnel area up to the temperature range of 200-450°C at which maximum efficiency occurs for catalytic ceramic filter systems. Thus, being able to locate the apparatus in the funnel is both cost effective and environmentally beneficial, because it avoids the need to boost the temperature with additional heat sources such as afterburners or heat exchangers.

The apparatus is advantageous as compared to the wet systems commonly used on ships because the pollutants are collected and treated in a dry state. This maximizes the effectiveness and ensures simple and straightforward handling, collection and disposal of spent reactants and generated waste. In particular, spent reactants can easily be stored whilst at sea and then transferred and treated on land, thus avoiding the need to discharge to the ocean. This has obvious benefits to the environment.

The apparatus is also able to remove pollutants to a much higher efficiency as compared to the wet systems commonly used on ships. Beneficially, the particulate removal efficiency of the present catalytic ceramic filter-based system is enough to remove the black plume of soot often associated with marine diesel engines.

In a second aspect, the present invention provides a method of pollution control comprising: providing apparatus according to the first aspect on a seafaring vessel; and positioning the apparatus such that the engine exhaust gas flows along the length of the catalytic ceramic filter elements.

The method may be carried out whilst the seafaring vessel is out at sea. The method permits the collection of sulphur oxides (SOx), nitrous oxides (NOx) and particulates from the engine exhaust gas.

The apparatus may be positioned adjacent to the funnel of the seafaring vessel. In a preferred embodiment, the heat generated by the engine heats the filter elements to a temperature within the range of 200-450°C, such as 300-350°C.

In a third aspect, the present invention provides the use of apparatus according to the first aspect to collect sulphur oxides (SOx), nitrous oxides (NOx) and particulates from the engine exhaust gas of a seafaring vessel whilst the vessel is at sea.

Detailed Description of the Invention Outer frame structure

The outer frame structure comprises a first pair of parallel frame members and a second pair of parallel frame members. It may usefully be that the outer frame structure is rectangular or square in shape; however other shapes may be contemplated such as a hexagon or octagon, or a rectangle or square with one or more truncated corners.

The outer frame structure may usefully be made from a metal or alloy material. Examples of suitable materials include steel, such as carbon steel (e.g. steel with a carbon content of about 0.04-2% by weight) and especially mild steel (mild steel has a low carbon content, e.g. about 0.04-0.3% by weight, compared to other carbon steels). The skilled person will recognise that economic concerns are likely to be a key influence on the choice of structural material, but that a range of alloys or metals may suitably be used, and that the expected conditions would be taken into account and may on occasion justify a more expensive material.

The outer frame structure may optionally be provided with one or more support units, e.g. in the form of plates and/or blocks. These are suitably located so as to support and stabilize the outer frame structure, in particular to support and stabilize the frame member or members to which the cage structures and/or filter elements are secured. For example, one or more L-shaped plates may be provided to support a frame member and/or one or more keep-blocks may be provided to stabilize a frame member in position.

In one embodiment, the frame member to which one or more cage structure and/or filter element is secured is provided with two L-shaped plate supports, one towards a first end of said frame member and one towards a second end of said frame member. L-shaped plates usefully provide support for said frame member by being secured both to said frame member and to a further frame member. They may reduce vibration or other motion for the cage structure and/or filter elements that are secured to the frame member.

Supporting cage structure

The apparatus includes one or more supporting cage structure, each of which is positioned within the outer frame structure. Preferably there are two or more, or four or more, or six or more, supporting cage structures. In one embodiment there are eight or more, or ten or more, or twelve or more, supporting cage structures.

It may be that there are from 2 to 40 supporting cage structures, each of which is within the outer frame structure, such as from 3 to 30, or from 4 to 20, supporting cage structures. In one embodiment there are from 8 to 40 supporting cage structures, each of which is within the outer frame structure, such as from 10 to 30, or from 12 to 20, supporting cage structures.

Each cage structure extends parallel to the first pair of parallel frame members and is secured to the outer frame structure. The supporting cage structures may, in one embodiment, be spaced in an equidistant manner between the first pair of parallel frame members.

The supporting cage structures may usefully be made from a metal or alloy material. Examples of suitable materials include steel, such as carbon steel. The skilled person will recognise that economic concerns are likely to be a key influence on the choice of structural material, but that a range of alloys or metals may suitably be used and the expected conditions would be taken into account and may on occasion justify a more expensive material.

Each cage structure comprises (i) a plurality of elongate bars arranged parallel to one another and spaced about a central elongate axis and (ii) a plurality of reinforcement bands, with each band extending around the perimeter of the spaced arrangement of bars. It may be that when there is more than one supporting cage structure, each cage structure is identical in design, but it can also be contemplated that they could be different, e.g. having different numbers of elongate bars and/or having different numbers of reinforcement bands.

In one embodiment, each cage structure comprises three or more, such as four or more or five or more elongate bars arranged parallel to one another and spaced about a central elongate axis. In a preferred embodiment, each cage structure comprises six or more, such as eight or more, or ten or more, elongate bars arranged parallel to one another and spaced about a central elongate axis. In one embodiment, each cage structure comprises from 3 to 20 elongate bars, such as from 4 to 16 elongate bars.

In one embodiment, the elongate bars are spaced in an equidistant manner about a central elongate axis.

In one embodiment, each cage structure comprises three or more, such as four or more, or five or more, reinforcement bands, with each band extending around the perimeter of the spaced arrangement of bars. In a preferred embodiment, each cage structure comprises six or more, such as eight or more, or ten or more, reinforcement bands, with each band extending around the perimeter of the spaced arrangement of bars. In one embodiment, each cage structure comprises from 4 to 30 reinforcement bands, such as from 6 to 20 reinforcement bands.

In one embodiment, the reinforcement bands are spaced in an equidistant manner along the length of the spaced arrangement of bars.

Catalytic ceramic filter elements

The apparatus includes a plurality of elongate catalytic ceramic filter elements, each of which is positioned within the outer frame structure.

Each filter element comprises porous ceramic outer walls which define a hollow inner section, wherein catalyst is disposed within the hollow inner section and/or embedded within the porous ceramic walls.

The porous ceramic walls may suitably be formed from inorganic mineral fibres that provide a porous matrix. The pores are able to capture particulates at the surface of the filter element. Such filter products are commercially available.

The thickness of the porous ceramic walls may suitably be from 4-25mm, but other thicknesses of wall could be chosen.

Catalysts for removal and elimination of SOx and NOx are known in the art. The catalyst may suitably be based on transition metals, or salts or oxides thereof; or precious metals, or salts or oxides thereof; or alumino-silicates. Salts may include chlorides and acetates, for example. Useful catalysts that can be specifically mentioned include those based on vanadium, salts or oxides thereof, e.g. vanadium pentoxide; or precious metals, salts or oxides thereof, e.g. palladium salts (such as palladium chloride and palladium acetate) and platinum metal; or zeolites. Other transition metals, such as manganese (or oxides or salts thereof) may also be used. The skilled person is aware of catalysts used in the treatment of pollutants and off gases and would be able to select a suitable catalyst when taking into account the fuel or fuel mixture that is being used on the seafaring vessel.

The catalyst is suitably contained within the hollow inner section or embedded within the porous ceramic matrix. This protects the catalyst from being coated with particulates, which are captured at the outer surface of the filter element. It will be appreciated that otherwise the particulates could adversely affect the activity and efficacy of the catalyst by physically blocking active sites or by chemically poisoning the catalyst.

Each filter element extends parallel to the first pair of parallel frame members and is secured to the outer frame structure. Each filter element also extends parallel and adjacent to a cage structure and is supported thereby.

It may be that more than one filter element is supported by a cage structure; for example, each cage structure may support one or two or three or four filter elements. In one preferred embodiment each cage structure supports two filter elements; it may be that these filter elements are spaced apart from one another, for example they may be located on opposite sides of the central elongate axis of the cage structure.

In one embodiment, the apparatus includes three or more, such as four or more, or six or more, elongate catalytic ceramic filter elements, each of which is positioned within the outer frame structure. In a preferred embodiment, the apparatus includes eight or more, such as ten or more, or twenty or more, elongate catalytic ceramic filter elements, each of which is positioned within the outer frame structure. In one embodiment, each apparatus comprises from 4 to 50 elongate catalytic ceramic filter elements, such as from 8 to 40 elongate catalytic ceramic filter elements.

Arrangements for securing Each cage structure extends parallel to the first pair of parallel frame members and is secured to the outer frame structure. In one embodiment, each cage structure is secured to the outer frame structure by a clamping arrangement. It may be that each cage structure is secured, directly or indirectly, to one of the second pair of parallel frame members, e.g. by a clamping arrangement.

Each filter element extends parallel to the first pair of parallel frame members and is secured to the outer frame structure. In one embodiment, each filter element is secured to the outer frame structure by a clamping arrangement. It may be that each filter element is secured, directly or indirectly, to one of the second pair of parallel frame members, e.g. by a clamping arrangement.

Each filter element extends parallel and adjacent to a cage structure and is supported thereby. In one embodiment, each filter element is secured to a cage structure. It may be that a retaining cap receives an end of the cage structure and an end of the (or each) filter element that is supported by said cage structure. Thus the (or each) filter element is secured adjacent to the cage structure by the retaining cap. It may be that there are two retaining caps per cage structure, one at each end of the cage structure, or it may be that a retaining cap is only provided at one end of each cage structure for securing one or more filter element thereto. A mechanical seal, such as a gasket, may be present to assist with securing and supporting the end of the (or each) filter element adjacent to the cage structure within the retaining cap.

Base support unit

In use, the pollution control apparatus may be supported on a base support unit. It will be appreciated that the pollution control apparatus may be provided in a form where it is connected to and supported by base support unit. However, the pollution control apparatus may also be provided separately from the base support unit and attached in use. The base support unit may be a pre-existing unit present on the seafaring vessel.

The pollution control apparatus may suitably be connected to and supported by the base support unit via one or more anti -vibration mounting. In one embodiment, two or more, such as four or more, or six or more, anti-vibration mountings are provided in a spaced arrangement to connect the pollution control apparatus to the base support unit. In one embodiment, the pollution control apparatus is provided with one or more support bracket and this can be used to connect the pollution control apparatus to the base support unit, optionally via an anti -vibration mounting. It may be that two or more, such as four or more, or six or more, support brackets are provided to connect the pollution control apparatus to the base support unit.

In a preferred embodiment, each support bracket is provided together with an antivibration mounting and in use is connected to the base support unit via said mounting.

The pollution control apparatus may be supported on a base support unit in a configuration where the filter elements run parallel to the floor (“horizontal configuration”) or the pollution control apparatus may be supported on a base support unit in a configuration where the filter elements run perpendicular to the floor (“vertical configuration”).

Venturi tube

The pollution control apparatus may optionally comprise one or more venturi tube. In a preferred embodiment, each cage structure is provided with a venturi tube. In particular, each cage structure may be provided with a venturi tube at or near one end of said cage structure, for example at or near an end of said cage structure that is adjacent to one of the second pair of parallel frame members. In use, the pollution control apparatus can be positioned such that the engine exhaust gas flows through the venturi tube and then along the length of the catalytic ceramic filter elements.

Description of the Drawings

Embodiments of the present invention will now be described in more detail with reference to the Figures, in which:

Figure 1 is a cross-section of pollution control apparatus according to the invention, in a vertical configuration;

Figure 2 shows a close up of section A in Figure 1 ;

Figure 3 shows a close up of section B in Figure 1 ; Figure 4 shows a close up of section C in Figure 1;

Figure 5 is a cross-section of pollution control apparatus according to the invention, in a horizontal configuration;

Figure 6 shows a close up of section A in Figure 5;

Figure 7 shows a close up of section B in Figure 5; and

Figure 8 shows a close up of section C in Figure 5.

The Figures illustrate pollution control apparatus 1 according to the invention, which is suitable for use on seafaring vessels.

The apparatus 1 comprises a rectangular outer frame structure. Therefore, the frame is made up of a first pair of parallel frame members 3 and a second pair of parallel frame members 2, the first pair of parallel frame members 3 being perpendicular to the second pair of parallel frame members 2.

The apparatus also comprises a plurality of supporting cage structures 5. Each cage structure 5 has (i) a plurality of elongate bars 5a arranged parallel to one another and spaced about a central elongate axis and (ii) a plurality of reinforcement bands 5b, with each band extending around the perimeter of the spaced arrangement of bars.

The apparatus 1 further comprises a plurality of elongate catalytic ceramic filter elements 4. These elements 4 run parallel to the cage structures 5 and are supported by these cage structures 5. In the illustrated embodiments, each cage structure 5 supports two elongate catalytic ceramic filter elements 4.

Each filter element 4 comprises porous ceramic outer walls which define a hollow inner section. Catalyst is disposed within the hollow inner section and/or within the porous ceramic walls. Catalytic ceramic filter elements of this type are known in the art and can be purchased commercially. The cage structures 5 and filter elements 4 extend parallel to the first pair of parallel frame members 3 and are secured to the outer frame structure, via one of the second pair of parallel frame members 2.

Retaining cap 6 receives an end of the cage structure 5 and an end of each filter element 4 that is supported by said cage structure 5. Thus both filter elements 4 are secured adjacent to the cage structure 5 by the retaining cap 6. A gasket 7 is also present to assist with securing and supporting the end of both filter elements within the retaining cap 6.

In addition, the cage structure 5 and each filter element 4 that is supported by said cage structure 5 are secured to one of the second pair of parallel frame members 2 by a clamping arrangement 9. A gasket 13 is also present as part of the arrangement to secure the cage structure 5 and each filter element 4 to the frame member 2.

The outer frame structure is provided with support units to support and stabilize the outer frame structure. L-shaped plates 10 are provided to support frame members 2, 3 at their intersection. In particular, the L-shaped plates 10 support the frame member 2 to which the cage structures 5 and filter elements 4 are secured. Keep-blocks 12 are also provided to stabilize this frame member 2 in position. Sealing plates 11 may also be provided.

In the vertical configuration embodiment (i.e. where, in use, the cage structures 5 and filter elements 4 are vertical) the retaining cap 6 may optionally be provided with a support beam 8 that extends vertically downward and which may contact a frame member, to provide additional support.

In the illustrated embodiments, each cage structure 5 is provided with a venturi tube 15 near an end of said cage structure that is adjacent to one of the second pair of parallel frame members 2.

The pollution control apparatus 1 is connected to and supported by a base support unit 14. Support brackets 15 connect the pollution control apparatus 1 to the base support unit 14 via anti -vibration mountings 16. In use, the apparatus 1 is positioned on a seafaring vessel, preferably near to the funnel, and is arranged such that the exhaust gas from the engine of the seafaring vessel flows through the venturi tubes 15 and along the length of the catalytic ceramic filter elements 4. The combination of the outer frame structure 2,3 and the supporting cage structures 5 provides robust support for the catalytic ceramic filter elements 4 whilst also ensuring that there is effective circulation of the engine exhaust gas in and around the catalytic ceramic filter elements 4. Therefore, the catalytic ceramic filter elements 4 are not damaged or destroyed by the conditions encountered at sea, whilst achieving effective capture and safe collection of pollutants generated by the engines of ships or other seafaring vessels.