AU765103B2

AU765103B2 - Method and device for preventing organism growth on sea-cases and sea water systems on ships, offshore platforms, etc

Info

Publication number: AU765103B2
Application number: AU22997/02A
Authority: AU
Inventors: Gunter Hoeffer; Stefan Sandrock; Eva-Maria Scharf
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-06-17
Filing date: 2002-03-07
Publication date: 2003-09-11
Anticipated expiration: 2020-06-17
Also published as: ATE259737T1; KR100615788B1; HK1047914B; AU2299702A; ES2215693T3; KR20020025078A; DE19960037A1; WO2000078605A1; HK1047914A1; JP4114769B2; EP1192075B1; CN1356946A; DE50005337D1; JP2003502072A; NO320943B1; PL352308A1; NO20016164D0; EP1192075A1; NO20016164L; CN1131158C

Abstract

The invention relates to a method and a device on ships, offshore-platforms, etc. for protecting against organism growth in complete seawater systems, operated on the basis of briefly raising the temperature of a volume of water (1) which is isolated by a mechanical closure system (4, 12). The brief temperature increase destroys the growth of organisms or their larvae without the need for toxic, environmentally damaging substances. Once the closure system has been opened, the normal cooling operation is resumed. The waste heat from the motor is used to raise the temperature for short periods of time. The mechanical closure of a sea-case is described as an application example. In cooling systems, comprising several circuits, joined by a mixing tank, each sub-circuit can be heated separately for a brief period, using the assembly of different heat exchangers and the integrated control and regulatory systems, thus preventing organism growth.

Description

METHOD AND DEVICE FOR PREVENTING ORGANISM GROWTH ON SEA CASES AND SEAWATER SYSTEMS ON SHIPS, OFFSHORE PLATFORMS

ETC.

FIELD OF THE INVENTION The invention refers to a method and a device for preventing organism growth on sea-cases, in particular sea case coolers as used on ships, offshore platforms, etc. for the protection of components such as filters, fittings, pipes, heat exchangers, pumps, sea-case coolers, etc. which are in sporadic contact with sea water in open sea cases and seawater systems.

BACKGROUND OF THE INVENTION There has been a considerable increase in organism growth on ships, ship components and pipeline systems and their components, due not least to increased water pollution. Various methods are being used on an international scale to reduce or prevent such fouling.

German Patent document DE-Al 31 23 682 describes an anti-fouling metallic material with alpha one-phase structure consisting of an alloy with 5 **•percent in weight Mn, and at least one element such as Sn with up to 5 percent in weight. The disadvantage here is that this is not a standard steel used for shipbuilding and would therefore make the ship a lot more expensive.

German Patent DE-A1 36 28 150, takes a similar approach by providing an adhering plate consisting of CuNi alloy plate with a primer so as to produce a selfadhesive layer. CuNi alloys are far more expensive materials than steel.

The outer surface of sea-going ships is currently protected from fouling by self-polishing anti-fouling coating systems. In this particular group, anti-fouling or corrosion-inhibiting protective layers are formed by plasma polymerisation as disclosed in German Patent document DE-Al 35 22 817, or a silicon rubber layer as per DE-A1 27 56 495 is applied to metallic surfaces. The disadvantage here is the contamination of the seawater with chemical substances.

Cathode protection systems are equally known where Cu ions are released from victim anodes as a result of an electrochemical potential, thereby preventing organism growth. Such system is very cost-intensive and also toxic.

In a system according to German Patent document DE-A1 41 09 197, voltage of variable polarity and strength is applied to a special anti-fouling protective coat for the production of a thin, anti-fouling water coat with changing pH values. The necessary multiple paint structure can be applied better to smooth surfaces than to cooling systems so that it is suitable for large-sized ship walls.

US patent specification 3,309,167 describes a method for preventing organism growth which exploits the anti-fouling effect of a regular to repetitive increase in temperature. In contrast to the invention featured below which aims to heat up the enclosed water in intermittently closed circuits through the engine heat, in the aforementioned US patent, the outside surface to be protected is heated directly by an electrical heating element, which requires additional energy.

US patent 3,650,677 refers to a method for sea cases with intermittent coating of the inner walls by adding vegetable oil and grease, particularly during the winter pause, to avoid destruction from ice formation and to prevent corrosion.

The higher temperatures stated in the patent specification refer to the heating of the oil and grease for spraying in the sea cases or to their removal at the end of the winter pause. Specific reference to the prevention of fouling is not obvious.

Fouling normally does not occur in winter when there is a risk of ice formation but in the late spring at temperatures exceeding 100C.

SUMMARY OF THE INVENTION 20 The current invention is based on the task of developing an effective, environmentally friendly method and device for inhibiting and preventing fouling at surfaces in contact with sea water in pipelines, filters, heat exchangers, fittings, pumps, sea case coolers and similar components of sea-cases that are in sporadic or constant contact with seawater, with the device being simple to use and install at low cost, requiring minimum operating costs and providing effective fouling protection without using toxic substances.

In accordance with a first aspect of the invention, there is provided a method for preventing organism growth by acorn barnacles, cockles and other fouling organisms on components in sea-cases, in particular on sea-case coolers, as used on ships and offshore platforms, by subjecting the fouling organisms in the sea-case to thermal overheating, characterised in that seawater contained in the sea-case is isolated from its surroundings, in that the sea-case cooler is taken off-line a cooling circuit it forms part of, and in that the sea-case cooler is mechanically switched into a high temperature heating circuit thereby using the sea case cooler for locally limited, brief and regularly repeated thermal overheating of the seawater enclosed in the sea-case thereby killing said fouling organisms.

In accordance with another aspect of the invention there is provided a device for carrying out the inventive method, characterised in that integrated measuring and control systems and adjusting devices are employed for automatic execution and monitoring of the local, short-term overheating of the sea case.

Generally, sea-case coolers for engine cooling water are treated with an anti-fouling coating but this only offers short-term fouling protection. Particularly the so-called low-temperature sea-case coolers with approx. 450C motor cooling water intake temperature offer ideal growth conditions for the larvae of acorn barnacles, cockles etc., so that after only a very short period the coolers are already extremely limited in performance because of fouling and have to be rated with a reserve surface area of >30% for safety reasons.

jBy contrast, high-temperature sea-case coolers with engine cooling water intake of approx. 750 900C are not or scarcely fouled by such organisms.

Studies have shown that fouling can be prevented permanently on the one hand by the effect of large shearing forces resulting from high flow speeds, or on the 20 other hand by locally and temporarily limited but regularly repeated brief overheating. In the latter case, prerequisite for economic implementation of temporary overheating of the water is to separate the water being heated from the surrounding water.

The advantages of the invention consist in the fact that by preventing organism growth on sea-case coolers, the cooling surface area can be reduced so that greater cooling capacities can be transferred with the same structural sizes, or sea-case coolers can be designed approx. 20% smaller and therefore lighter with the same cooling capacity so that they can frequently be fitted into far smaller sea cases. The minimised structural size and the possibility once again of using normal steel for the bundle of pipes in turn results in a considerable cost reduction in the sea case cooler itself. It is now possible to dispense with any possible spare coolers. The energy required to heat up the enclosed seawater is 4 provided by the high-temperature cooling water of the main engine or the diesel generator cooling water.

The complete sea-case with all installations can be preserved with the same coating system so that the costly coating of the CuNil0 Fe bundle of pipes and the associated problems of electrolytic corrosion following damage to the coating of the pipes no longer apply.

Finally it is also worth mentioning the fact that this sealing mechanism can also be retrofitted to ships which are already in operation.

The invention is explained in greater detail below on the basis of several 10 examples illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 Basic structure of a sea-case with closing inlet and inlet slots Fig. 2 Sea-case with closed outlet slots Fig. 3 Sea-case slats for closing the inlet slots Fig. 4 As fig. 1, combined cooler, low-temperature sea-case cooler with integrated high-temperature sea-case cooler S.Fig. 5 Diagram to show a high-temperature and low-temperature circuit with additional external heat exchanger Fig. 6 Rollable elastic plate for closing the inlet and outlet slots *o 20 Fig. 7 Circuit structure of the sea-cases for alternating sea and cleaning operation.

DESCRIPTION OF PREFERRED EMBODIMENT

S

The locally limited heating up of the seawater in a closed sea-case 1 utilises the high-temperature cooling water of the main engine 13, or alternatively the cylinder cooling water from the diesel generators, with change-over fittings on the low-temperature cooling water circuit for case cooler 2.

Fig. 1 shows the basic structure of a sea-case 1 with low-temperature seacase cooler 2, sea-case slats 4 with slat case 12 for closing the outlet slots 3.

The inlet slots 8 are closed in the same way. Other installations include the ventilation 5, rinsing connection 6, zinc anode 7.

In normal operation (sea operation), the low-temperature engine cooling water circulates at approx. 45 0 C through the low-temperature sea-case cooler 2 and the seawater flows with max. 32°C through the inlet slots 8 into the sea-case 1. This seawater cools the engine cooling water down via the low-temperature sea-case cooler 2 to minimum 36 0 C and leaves the sea-case 1 through the outlet slats 3. With the seawater, the larvae of the fouling organisms continually flow into sea-case 1. While travelling through estuaries and while mooring in ports or at anchor, these larvae settle in sea case 1 and its installations. According to the invention, in sea case 1, the inlet slots 8 and outlet slots 3 are now closed by the sea case slats 4. Under particularly favourable temperature circumstances and structural conditions, it may be sufficient just to close the outlet slots.

Fig. 2 shows the structure of the sea case slats 4 illustrated by the closure mechanism for the outlet slots 3. It consists of the drive 10, the slats case 12 and the individual slats. The guide rail 11 is mounted on the inside of the outer layer Sof the sea-case 1 with the necessary bracing and a peripheral seal if necessary to make the system waterproof. The ventilation 5 is responsible for balancing the pressure when the inlet and outlets slots 8 and 3 are closed by the sea-case slats 4.

Fig. 3 shows the arrangement of the low-temperature sea case cooler 2 via the inlet slots 8 and the sea-case slats 4 to the closure of the inlet slots 8 and outlet slots 3.

Fig. 4 presents a possibility for directly heating sea-case 1 via the high- 20 temperature bundle of pipes 9 of the high temperature circuit integrated in the socalled combined cooler, or the cooling water circuit of the diesel generators, with min. 70 0 C inlet temperature. The basic structure corresponds to fig. 1. The locally and temporarily limited brief overheating with closed inlet and outlet slots 8 and 3 is produced here by the integrated high-temperature pipes 9 in the same way as described below under fig. Fig. 5 shows the R&I diagram for an engine with separate hightemperature and low-temperature cooling water circuit. The high-temperature engine cooling water is cooled down by the low-temperature cooling water in normal operating mode via the panel heat exchanger 14. At the same time the low-temperature cooling water dissipates the absorbed warmth via the lowtemperature sea case cooler 2 to the seawater when the inlet and outlet slots 8 and 3 are open.

In port or at anchor, when the main engine 13 is switched off, the overheating mode starts for the low-temperature sea-case cooler 2 which is brought up to a minimum of 600C to kill off the fouling organisms. The bypass of temperature control valve 16 is closed completely. In this way, the hightemperature cooling water heats the low-temperature cooling water via the panel heat exchanger 14. The sea water in the sea-case is overheated briefly and locally for a certain period of time to min. 600C by the low temperature cooling water circulating in the closed circuit via the low-temperature sea-case cooler 2, so that the fouliri'g organisms are killed off.

After opening the sealed inlet and/or outlet slots 8 and 3, if necessary seacase 1 can be rinsed briefly via the rinsing connection 5, and the low-temperature sea case cooler 2 is brought back to normal operation by proceeding with the S. :measures described above in reverse order.

Fig. 5 also shows a suggestion for reducing the heating up period by integrating a heat exchanger 15 in the low temperature circuit which is heated by steam, thermal oil or electrical energy.

Fig. 6 shows another possible design as movable elastic plate 17 which can be fitted into the contour of the outer surface of the ship as a water-proof Sclosing device for the inlet and outlet slots 8 and 3. The static pressure acting on 20 plate 17 presses plate 17 against the outer surface of the ship designed in this section of sea- case 1 as a double skin 18.

eeoe Fig. 7 shows the seawater system consisting of sea cases 1A and 1B and connected via pipes and/or conduits with the integrated shut-off fittings 21 and 22, pumps 20 and mixing tank 19. In sea mode, fittings 21 and 22 and the slats 4A and 4B in sea cases 1A and 1B are open.

In port or at anchor when moving at reduced ship speed or while moored, the slats 4A in sea-case 1B are closed and the corresponding shut-off fittings 22B and the fitting 22A in the active sea case 1A are opened to separate the system into passive partial system B cleaning mode and active partial system A sea mode. Now the sea-case 1 B with its corresponding connection pipes, fittings 21 B and 22B, case coolers 2B and pumps 20B are limited locally and subjected to brief thermal overheating to prevent the growth of micro-organisms, macroorganisms and their larvae.

Other sea-cases and their connected pipeline systems can be protected from fouling section by section using the same method.

List of reference numbers 1 Sea-case 1A Sea-case 1B Sea-case 2 Low-temperature sea-case cooler 2A Low-temperature sea-case cooler 2B Low-temperature sea-case cooler 3 Outlet slots 4 4 Sea-case slats 4A Sea-case slats S. 4B Sea-case slats S. 5 Ventilation o.

6 Rinsing connection 7 Zinc anode 8 Inlet slots 9 Integrated high-temperature bundle of pipes ".10 Slat drive 11 Guide rail 12 Slat case :°oooo 13 Main engine 14 Panel heat exchanger Additional heat exchanger 16 Temperature control value 17 Moving elastic plate 18 Double skin 19 Mixing tank Seawater circulation pump, active 20B Seawater circulation pump, passive 21A and B: Shut-off fittings, seawater feed, active/passive 22A and B: Shut-off fittings, seawater return, active/passive.

Claims

1. Method for preventing organism growth by acorn barnacles, cockles and other fouling organisms on components in sea-cases, in particular on sea-case coolers, as used on ships and offshore platforms, by subjecting the fouling organisms in the sea-case to thermal overheating, characterised in that seawater contained in the sea-case is isolated from its surroundings, in that the sea-case cooler is taken off-line a cooling circuit it forms part of, and in that the sea-case cooler is mechanically switched into a high temperature heating circuit thereby using the sea case cooler for locally limited, brief and regularly repeated thermal overheating of the seawater enclosed in the sea-case thereby killing said fouling organisms.

2. Method according to claim 1, characterised in that in a seawater system having several of said sea-cases with connecting pipes, conduits, sea-case coolers, pumps and fittings, the enclosed seawater is regularly thermally overheated section by section so that the whole seawater system is protected section by section from fouling by the overheated enclosed seawater.

3. Method according to claims 1 and 2, characterised in that for sea-cases without sea-case coolers, prevention of fouling is effected by means of an additional heat exchanger tube bundle mounted directly in the sea-case and which is arranged 'to effect locally contained, brief and regularly repeated overheating of seawater.

4. Method according to any one of claims 1 to 3, characterised in that the isolated components of the sea-case are rinsed with fresh water through a rinsing connection before or after the local overheating phase. Method according to any one of claims 1 to 5, characterised in that integrated measuring and control systems and adjusting devices are employed for automatic execution and monitoring of the local, short-term overheating of the sea case.

6. Device for carrying out the method according to any one of claims 1 to characterised in that individual sea-cases of a seawater system, their connecting pipes and conduits and components installed in the seawater systems, such as sea case coolers, pumps and fittings, are arranged to form separatable sections or sub systems to allow for short-term, localised and regular thermal overheating of the seawater enclosed in each section, thus protecting the whole seawater system section by section from organism growth.

7. Device according to claim 6, characterised in that the sub systems are divided into an active partial system characterised by open slats in an active sea- .case and closed first shut-off fitting and closed second shut-off fitting in a passive sea-case during sea operation, and a passive partial system characterised by closed slats in the passive sea case and opened third shut-off fitting and opened fourth shut-off fitting in the active sea case during cleaning operation.

8. Device according to claim 6 or 7, characterised in that the sea-case is equipped with outlet slots and inlet slots arranged in the outer surface of the ship, and in that closure devices are provided to seal these mechanically either individually or jointly.

9. Device according to claim 8, characterised in that the closure devices comprise slats. Device according to claim 8, characterised in that the closure devices comprise elastic moving plates.

11. Device according to claim 8, 9 or 10, characterised by a plurality of individual drives or a common drive arranged to drive the closure devices.

12. Device according to any one of claims 8 to 11, characterised in that the closure devices are provided with components coated with special anti-fouling, friction-reducing materials, particularly tetrafluoroethylene.

13. Device according to any one of claims 6 to 12, characterised in that an additional pipe bundle heat exchanger that forms part of a high-temperature circuit of a main engine of the ship or offshore platform is integrated in the sea- case cooler for rapid local heating-up of the enclosed seawater.

14. Device according to any one of claims 8 to 13, characterised in that steam distribution lances are installed in the sea-cases. DATED this 6th day of March 2002 GUNTER HOEFFER *RIVERSIDE CORPORATE PARK

39-117 DELHI ROAD NORTH RYDE NEW SOUTH WALES 2113 SAUSTRALIA SP20699AU CJ/HB P20699AU00 CJS/HB S S*