NO20100543A1 - System and methods for purification and conversion of ballast water to fresh water during sea voyage, purification of exhaust gas and energy optimization on board vessels - Google Patents

Description

System and methods for purification and conversion of ballast water to fresh water during sea voyages, purification of waste gas and energy optimization on board vessels

The invention is a practical system and method that will initially be able to produce fresh water and seawater with a high salt content (brine) from ballast and seawater on board existing vessels, without major conversions being necessary.

The way the inventor has composed the system and developed the methods will create new business opportunities for shipowners, as well as contributing in a positive way to solving the ballast water problem and providing increased access to fresh water in coastal areas around the world. Furthermore, the same system will provide the opportunity to reduce fuel consumption by as much as 30 - 40%, if the entire system is implemented as a whole on existing ships.

The inventor seeks priority in previously submitted patent applications as they are based on the same system, principle and idea.

The following priority requirements:

20090399 submitted in Norway on January 27, 2009

20093027 submitted in Norway 20 September 2009

Technique the invention is based on

Reverse osmosis ( 3)

This is a well-established method for the production of fresh water, which is considered to be the best commercial filtration technique for fresh water today. There are especially new design solutions for pre- and post-treatment systems associated with the reverse osmosis plant which now make it possible to obtain fresh water of very high quality at competitive production costs (about 0.30 US$/ metric ton).

Ultra-(UF) or microfiltration (MF)

By using UF or MF (0.1 (in filter) as a pre-filtration system, the lifetime of the reverse osmosis membranes is increased by up to two times, and the need for chemical additives when pre-treating the water is reduced. Replacement of the reverse osmosis membranes is the biggest contributor to the lifetime costs of a reverse osmosis plant New techniques have also managed to reduce energy consumption by 65%.

Electrolysis of water with a high salt content (Chlorine-Alkali process)

Electrolysis of water with a high salt content (brine) is widely known industrially and used on a large scale worldwide for the production of chlorine, caustic soda and partly hydrogen. In recent years, in the maritime industry, electrolysis of pure seawater has started to be used in connection with ballast water purification systems (with reference to Hamworthy-GreenShip) and to make seawater more alkaline before it is used in an exhaust gas scrubber, with the aim of improving emission reduction ( with reference to EcoSpec).

Ballast water treatment systems ( 5)

New international rules for handling ballast water have already been approved and will come into force in the period 2012-2018 for large vessels (with reference to IMO rules and guidelines MEPC. 125(53) and MEPC. 126(53)). All ships in international trade will be required to have an approved ballast cleaning system during the said period.

Such a system aims, among other things, to render marine organisms in the ballast water harmless before they are released.Introduction of these new species could create an imbalance and be directly harmful to the existing marine environment in another part of the world. Hamworthy-GreenShip has presented a system that is based on filtration/separation and electrolysis, as well as oxidation of the seawater, before it is pumped into the ballast tanks (1). Other suppliers have systems that both clean incoming ballast water during ballasting and outgoing ballast water during de-ballasting for the simple reason that the facilities often become very large due to the handling of large amounts of ballast water volume during the short port stays.

Ballast water requirement for tankers is approximately 26% of the ship's deadweight. This involves approximately 80,000 tonnes of ballast water for the largest heavy oil tankers.

Desulfurization of bunker oil ( 12)

A patent dating back to 1920 describes a method for binding sulfur in bunker oil by adding chemicals that form new salt crystals. This was a method that could have reduced SOx emissions into the atmosphere in the internal combustion engines of the time. Grounded

considerable increase in the salt content of the bunker oil, this is not a practical solution today. The inventor has continued to work with this as a starting point and tests indicate that the salt content can be washed out in a suitable separator, as well as that both caustic soda (NaOH) and hydrogen (H2) from the electrolysis process can provide a breakthrough for technologies that can effectively clean out sulfur from the bunker oil before it is burned in the engines/boilers. A separate patent application will be filed for this system and method.

Hydrogen Selective Catalysis (xx)

Membrane technologies already exist today for the reduction of NOx, Hydrocarbons and particles in exhaust gas from internal combustion engines. There are no such installations on board ships, as both the safe handling and procurement of the hydrogen gas have not been considered appropriate to the inventor's knowledge. With new defined international emission requirements, and the inventor's safer and more cost-effective method for obtaining hydrogen, this could become very attractive for shipowners.

Methanation ( xx )

Methanation is a well-known chemical process from industry. Suitable membranes already exist in

market to exploit internal combustion engine exhaust gas temperature (>300 degrees C), to chemically allow C02 and water vapor in the exhaust gas to react with added hydrogen to form methane (CH4) which can be fed back as fuel, especially in gas-powered or dual-fuel internal combustion engines. The problem is cost-effective access to hydrogen or a hydrogen carrier.

Exhaust gas cleaning system

The market for exhaust gas treatment plants is in the process of being established, based on new international emission requirements, especially in connection with sulfur emissions into the atmosphere. Various technologies have already been tested and are in the process of being introduced to the market. What these have in common is that they depend on an alkaline substance in the feed water to function nutritionally efficiently.

Bunker expenses could increase significantly for ship owners (~40%) if cleaning technologies such as scrubbers do not prove to work satisfactorily.

There are different types of scrubber solutions. A so-called "open" scrubber solution is characterized by the fact that surrounding seawater is used as feed water. The feed water is processed through the scrubber and the main part of the wash water is pumped overboard after it has been cleaned in a treatment step to meet current discharge requirements. Large amounts of seawater are needed both to bind the sulfur and large amounts of seawater are needed to dilute the wash water so that it does not become too acidic (low pH) to be discharged.

A "closed" scrubber solution is characterized by fresh water dosed with smaller amounts of caustic soda (NaOH) forming the feed water for the scrubber. A smaller portion of fresh water will be replenished as some of the wash water is cleaned out and some feed water disappears in the chimney, but mainly the feed water circulates in the system - hence the name "closed system".

The Singapore-based company EcoSpec has a system that reduces both SOx, NOx and C02 gases.

Organic Rankin Cycle plant - ORC (xx)

Technologies exist today that can convert excess heat into electricity, where the heat source/medium is as low as 60-100 degrees Celsius.

Advantages of using the technique in a new way

The shipping industry faces many very difficult tasks in meeting a number of environmental requirements over the next decade. If you try to solve the problems one by one rather than holistically, there is a tendency that the solutions are not optimal and in most cases both the installation and operating expenses for shipowners or charterers increase. Ships on ballast voyages generate no income for shipowners, as the ship is empty of commercial goods. Due to major environmental repercussions from the transport and discharge of, among other things, marine organisms from ballast water in foreign ports, new international rules have come into place. This means that larger investments and higher operating expenses will now affect the shipowners - in that they must render the marine organisms harmless before the ballast water is released and new cargo comes on board.

On this occasion, the inventor has found a system and methods which relatively easily solve the ballast water problem, but which also help to solve other bigger problems - namely access to fresh water in the world, as well as the reduction of fuel consumption and emissions of environmental gases. The solution will mean that shipowners can make money by reselling the "ballast water" during or after the ballast voyage. The invention is a practical system and method which will initially be able to convert ballast water into fresh water on board existing vessels, without major conversions being necessary.

Approximately 5-8 billion tonnes of ballast water are transported around the world on an annual basis. The world's population has an ever-increasing need for fresh water, and coastal areas seem to be most affected in the future. Only 8% of the fresh water requirement is clean drinking water, which means that the inventor focuses commercially on a solution to produce fresh water for industrial use and for agricultural purposes. If clean drinking water has to be procured based on receipt from ships, this will be most cost-effective at the receiving terminal, as the converted ballast water has already been desalinated and simple filtration technology can be used.

Further analysis shows that the ports/areas in the world that are most exposed to ripple effects from the release of marine organisms are also ports and states that will desperately need fresh water in the future.

As 90% of all goods transport in the world is carried out by ship, this is a very flexible and new way of bringing more fresh water to sometimes exposed places in the world.

The initial system and method is best described as follows:

A typical tanker can have up to twelve ballast tanks, six on each side, for the best possible stability characteristics during sea travel without cargo. A typical ballast tank division for a tanker is illustrated in figure 1. For simplicity, we use a -1- ballast tank (1) in the system description below (figure 2.). In each ballast tank, in the inventor's solution, there will be a defined layer with a liquid membrane (2) characterized by a 30-40 cm thick layer of non-compressible, non-abrasive small spheres with a density of 1.010 dm3/kg which will be able to achieve several intentions; • Fresh water (a) with a density of approx. 1,000 dm3/kg and ballast (sea) water (b) with a density of approx. 1.025 cm3/kg in the same tank will be effectively separated using the liquid membrane/balls, so that osmotic effects between the two liquids do not take place. The fresh water will always lie at the top of the tank due to its density, with the balls and then the ballast water at the bottom of the tank. • The layer's thickness of 30-40 cm will also ensure that this separation is maintained in the event of greater relative movements in the tanks during sea travel. • The small balls will also be able to be effectively stopped in grates/filters/grids in front of the pump equipment. The pumps will automatically stop if the suction pressure is too high, but preferably with level sensors of the float type, for example.

The ballast water (b) in the tank will be continuously emptied by a service pump (3) during sea travel. A control valve (4) will ensure that sufficient seawater (b2) from the sea boxes (5)

is mixed with the ballast water (bl), so that the same amount of ballast water is pumped out of the tank as comes in from ready-made fresh water (al) in the tank. Mixing ballast water (bl) and seawater (b2) is dependent on the reverse osmosis plant's (8) efficiency. Normally, 40% of supplied sea/ballast water will become produced fresh water.

The feed water (b3) to the reverse osmosis system (8) is regulated by the feed water pump (6), where this is first passed through a MF/UF pre-filter (7) with a filter density of 0.1 [ in. Almost all potential bacteria or larger particles from the ballast tank will be stopped in the filter. Automatic mechanical cleaning of the MF/UF filter (7) using air and then backwashing of the filter occurs with minimal use of fresh water produced (a2).

Pre-filtered feed water (b3) is then led to the reverse osmosis membranes (8). The reverse osmosis plant (8) produces approximately 40% fresh water (al) which is led back to the ballast tank (1).

Reverse osmosis membranes are among the best filtration technology available (HF hyperfilter). No harmful bacteria or viruses pass the membrane, but proceed with the rejected seawater (cl) with an elevated salt content (approx. 67% higher than normal seawater) - which is called brine.

Several studies have shown that most marine organisms cannot tolerate rapid changes/

increased salt content, which speaks in favor of the inventor's system for ballast cleaning. The inventor's solution further involves utilizing this apparent waste product after water production. The brine (cl) is then led into a multi-stage electrolysis apparatus (9). A number of recently approved ballast water treatment systems use electrolysis as the main element for combating marine organisms. The advantage of the inventor's solution is that brine (cl) is used as a starting point rather than seawater. This provides a significantly more cost-effective and space-optimized electrolysis apparatus (9) due to the higher salt concentration, as well as handling the waste product for further process optimization of the system.

When all the ballast water has been converted to fresh water in the first tank (1), you will sequentially continue with the next ballast water tank. Depending on the duration of the sea voyage in relation to the installed equipment, one can envisage several transfers of fresh water at central locations around the world. The probably most rational ways of transferring the fresh water will be;

- Ship-to-ship transfer

- Connection to loading buoys outside the port/terminal area.

In the case of a ship-to-ship transfer, you will be able to do this while waiting for the ship to pass through, for example, the Suez Canal. By using decommissioned/old single-hull tankers such as (FWPSO) Floating- Freshwater-Storage- Unloading-Ship (e.g. 300,000 dwt) it will be possible to receive 5-10 cargoes during a day, and then sail these to port in for example Egypt or Israel. An advance of $0.10/ metric ton of fresh water will give a higher day rate than most merchant ships. The merchant ship that gave up the fresh water cargo will be able to take in new ballast water outside the contaminated port/terminal area, and carry out one or more ballast water conversions during further sea voyages.

If the merchant ship is close to its destination and within the approved IMO ballast water area, it only takes the new ballast water to the terminal and then dumps this when re-loading, without the risk of transporting marine organisms from distant waters.

The transfer/unloading of fresh water will take place in the following way;

The ship's existing ballast pumps (10) will be used during the transfer/unloading of fresh water by pumping new seawater (b4) from the sea boxes (5) into the aforementioned ballast tank (1). Coarse filter/separator (11) is placed after the ballast pumps (10) to prevent unnecessary sediments such as sand and plankton from entering the ballast tank (1). Figure 3 describes the fresh water unloading arrangement at the top of the ballast tank. The principle is that the new ballast (sea) water (b5) that is pumped into the tank will further push the fresh water (a3) out of the tank and through the main fresh water distribution pipe (12) on deck. A submerged bilge pump (13) in each of the ballast tanks will at the same time remedy the pumping work with suction from the fresh water side (a). The membrane balls (2) will constantly be a buffer between the ballast water (b) and the fresh water (a) in the tank. The ballast tanks will normally have a 95% degree of filling. Based on level floats (14) and pressure sensors on pumps, pump controls will ensure that this level is maintained at all times. The unloading operation will preferably end and pumps are stopped by the level floats (14) being activated, or by the membrane balls (2) covering the bilge pump's intake strainers (13a) and the mass flow meters (15) activating the stop of said pump. Own by-pass pipe (16) with non-return valve (17) and grate/grid at the pipe inlet, and a pressure-regulated tank ventilation head (18) is connected to each tank in accordance with international class requirements for ships.

For shipowners, in various cases it may also be appropriate to build a more redundant ballast water purification system, if;

Existing equipment does not have enough capacity to convert all the ballast water into fresh water due to shorter routes than the minimum defined at installation, or that the ship must interrupt the route after sailing into a new IMO defined ballast area.

Thus, if you build a conventional ballast treatment system with a reduced capacity, you can

one converts a defined amount of ballast water tanks while cleaning and dumping remaining tanks when loading in a new port.

In order for the inventor's system and method to achieve IMO approval as a ballast cleaning system, the backwashed fresh water (a2) used to clean the MF / UF filters (7) must also be cleaned (ref. figure 2) We are talking about a volume of less than 2% of original ballast water, while this can be done during the entire sea voyage rather than for a short time at the loading/unloading terminal. As a supplement to the inventor's solution, a conventional ballast water purification system will be very modest in size and scope,

System and methods for energy optimization and exhaust gas purification are described as follows: Regardless of the fact that the initial system inactivates the marine organisms by, among other things, the electrolysis of the brine, and thus solves the ballast water purification problem, the inventor gets significantly higher effects when the end products; hydrogen (dl), caustic soda (d2), sodium hypochlorite (d3) or magnesium chlorite after electrolysis

the process is further utilized (figure 2).

Both weak solutions of caustic soda (d2) and sodium hypochlorite (d3) are basic, so that if this is pumped overboard in controlled forms together with other cooling water from machinery, this will help to slow down the acidification somewhat in the sea based on the global increase of C02 in the atmosphere/ saturated in the water. On the other hand, these chemical solutions/gases are too valuable to be dumped/vented directly.

Electrolysis apparatus (9) which forms, among other things, hydrogen (dl) and caustic soda (d2) will be placed directly in the exhaust gas chimney, where hydrogen production will be in the immediate vicinity of the location of a Hydrogen-Selective Catalytic Reactor - H-SCR (20 ) which will be installed just before the ship's exhaust boiler (21). This cleaning technology will provide more residual heat in an exhaust gas boiler (21) due to its exothermic reaction, while at the same time it will "burn" 90-95% of NOx, hydrocarbons, organic elements and particles in the exhaust gas.

The hydrogen (dl) can also be used a) in a fuel cell, b) for hydrogenation of fuel or c) for methanation of C02 in exhaust gas. The latter technology (22) utilizes C02 and water vapor from the exhaust gas which is converted into synthesis gas (d4) (CH4) which can in turn be used back as fuel for gas/dual-fuel combustion engines (23).

Parts of the caustic soda (d2a) solution produced in the electrolysis apparatus (9) in the chimney will be pumped directly to the bunker separator room, and will be used in a desulphurisation apparatus (24). The desulfurization separator will reduce/wash out sulfur in the bunker oil (d5) before it is injected

in the internal combustion engine (23).

This technology is cost and energy-economically very advantageous compared to exhaust gas treatment plants for SOx, placed after the exhaust boilers, as the exhaust boilers (21) where the desulphurization separator (24) is installed, can be modified to take out more residual heat - by lowering the temperature of the exhaust gas without encountering traditional corrosion problems due to sulfuric acid precipitation in the exhaust pipes.

Remaining amounts of caustic soda solution (d2b) are used in waste gas treatment plants (25)

(scrubber) for reduction of C02 gas and residual amounts of NOx and soot particles to exceed new emission requirements.

The strength of the electrolysis will be adjusted in relation to the direct need for the end products.

Microturbine (26) and Organic-Rankine-Cycle plant (27) will be used to utilize as much residual heat as possible from the internal combustion engine's (23) cooling system and exhaust gas boilers (21), but also heat exchange the washing water (electricity) from the scrubber with the ORC plant. Pipe loops (e2) with washing water (electricity) from the waste gas treatment plant (25) are led into the modified waste gas boiler (21) and are heated close to the boiling point of the liquid and are then used as a heat source for preheating in an Organic Rankin Cycle (27) plant . The inventor's system has the potential to increase the amount of residual heat by a factor of approx. 2 compared to existing ship solutions.

The cooling water (fl) (~60 °C) from the ORC plant (27) will further be used as preheating of the feed water (b4) in a heat exchanger (28) for the reverse osmosis (8). Reverse osmosis plants have a maximum feed water capacity of approx. 27 degrees Celsius. For every two degree reduction in feed water temperature, the capacity will be reduced by 5%. The inventor's solution will thus ensure maximum production regardless of the surrounding seawater temperature. In colder areas, this will lead to significant savings in water costs and bunkers.

Technical component composition of the invention:

Complete Reverse Osmosis plant (7,8,28);

Reverse Osmosis is well known, tested and established only in the cruise market as a supplement to evaporators. The facility has the following additional equipment/components:

Energy Recovery Device (ERT). New technology entering the market

Ultra or Microfilter pre-filtering system (7). New technology has already been tested in the market

Automatic mineralization/softening filter with hardness control (C02 or hydrochloric acid) based on the parameters; temperature, pH, and conductivity (microSiemens/cm). New technology has already been tested in the market.

Chlorination or UV irradiation facilities for disinfecting produced water. Standard technology is known in the market.

Furthermore, the following equipment is included in the inventor's system:

Desulfurization separator (24): New technology entering the market

Electrolysis apparatus(9): Well-known, but new technology entering the market Methanization equipment(22): Well-known, but new technology entering the market Hydrogen SCR (20): Known technology.

Organic Rankine Cycle (ORC)(27). Well known technology.

Micro turbine (26). Well known technology.

Exhaust gas treatment plant (scrubber) (25). New technology entering the market

Claims (7)

1. A system and a method for purifying ballast water by converting ballast water to fresh water in existing ballast tanks on board sailing ships, characterized by the use of a defined layer of non-compressible, non-abrasive balls with a density of 1.010-1.015 dm3/kg which at all times will form a liquid membrane between fresh water and ballast water in the tank so that osmotic effects between the liquids do not occur, where ballast water is pumped from the bottom of the ballast tank to a combined ultra/micro- and hyperfiltration system (complete reverse osmosis system), produced fresh water is pumped back to the top of the ballast tank and condensate (brine) is pumped on to a multi-stage electrolysis device for the inactivation of marine organisms and the production of useful end products such as hydrogen, caustic soda or hydrogen and sodium hypochlorite/magnesium chlorite - for further use in the system. 2. A system and a method according to claim 1, characterized in that hydrogen produced cost-effectively from reverse osmosis condensate (brine) in electrolysis, the device is led to a Hydrogen Selective Catalytic Reactor (H-SCR) for near total reduction of NOx gases, hydrocarbons and organic compounds in the exhaust gas, at the same time that this exothermic reaction produces more residual heat in the exhaust gas that can be used for increased steam production in the ship's exhaust boiler after modification. 3. A system and a method according to claim 1, characterized by hydrogen produced cost-effectively from reverse osmosis condensate (brine) in electrolysis, the device is led to a methanation reactor where the hydrogen together with C02 and water vapor from the exhaust gas is converted into synthesis gas (CH4) which can again be used as fuel for gas/dual-fuel combustion engines. 4. A system and a method according to claim 1, characterized in that parts of the caustic soda solution (NaOH) produced cost-effectively from the reverse osmosis condensate (brine) in the electrolysis device are led to a desulphurisation separator for reducing sulfur in the bunker oil before it is injected into the combustion engine to meet new emission requirements and that the flue gas boiler can be modified to extract more residual heat without encountering corrosion problems due to sulfur precipitation in the flue gas. 5. A system and a method according to claim 1, characterized in that the remainder of the caustic soda solution (NaOH) produced cost-effectively from the reverse osmosis condensate (brine) in the electrolysis apparatus is directed to an exhaust gas treatment plant (scrubber) for reduction of C02 and residual amounts of NOx and soot particles to meet new emission requirements. 6. A system and a method according to claims 1, 2 and 4, characterized in that pipe loops with washing water from the waste gas treatment plant are led into the modified waste gas boiler and are heated close to the boiling point of the liquid and are then used as a heat source for preheating in an Organic Rankin Cycle (ORC) plant, in the same way as excess heat from the engine's cooling water and steam produced from the modified exhaust gas boiler, and furthermore that the cooling water from the condenser of the ORC plant is heat exchanged with the feed water to the reverse osmosis plant to ensure a constant high temperature and thus maximum production regardless of the seawater temperature. 7. Application of the systems and methods according to claims 1-6 is not limited to ships, but will also have the same effect at power-producing facilities on land with associated water production using reverse osmosis technology or on fixed and floating installations offshore.