WO2007040407A1 - A method for preventing growth of biological material in a water-based heat exchanger system - Google Patents

A method for preventing growth of biological material in a water-based heat exchanger system Download PDF

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Publication number
WO2007040407A1
WO2007040407A1 PCT/NO2006/000339 NO2006000339W WO2007040407A1 WO 2007040407 A1 WO2007040407 A1 WO 2007040407A1 NO 2006000339 W NO2006000339 W NO 2006000339W WO 2007040407 A1 WO2007040407 A1 WO 2007040407A1
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WIPO (PCT)
Prior art keywords
water
circulation loop
antifouling
treatment
installation
Prior art date
Application number
PCT/NO2006/000339
Other languages
French (fr)
Inventor
Svein Børge HELLESMARK
Per Gunnar Andersen
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Torp Technology As
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Publication date
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Publication of WO2007040407A1 publication Critical patent/WO2007040407A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
    • F28G9/00—Cleaning by flushing or washing, e.g. with chemical solvents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
    • C02F2103/023—Water in cooling circuits
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/04—Flow arrangements
    • C02F2301/046—Recirculation with an external loop
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/04—Disinfection

Definitions

  • the invention relates to a system for preventing or limiting growth of biological material in a water-based heat exchanger system, more exactly to prevent or moderate growth, i.e. growth of algae, mussels etc., in seawater flowlines and the like in a heat exchanger installation utilising water as the heat energy source .
  • the object of the invention is to remedy or reduce at least one of the disadvantages of the prior art.
  • the invention relates to a method for at least to moderate growth of biological material in a heat exchanger installation that is arranged to be able to circulate water through conduits, valves and at least one evaporator and where water, especially seawater, is a heat energy source, the method comprising the steps of:
  • the antifouling medium is preferably added at least at the at least one evaporator.
  • the antifouling medium being added is adapted to the existing flora and fauna in the water being utilised as heat energy source, as a relevant field professional person will choose one or more suitable antifouling media in a suitable concentration based on knowledge of the water characteristics and the antifouling properties towards the unwanted organisms.
  • the antifouling medium is, as an example, a metal based chemical compound or a gas.
  • An example of a metal-based compound is sodium hypochlorite.
  • An example of a gas is ozone.
  • the dosing of the antifouling medium or the mixture of multiple antifouling media to the water is made continuously or at intervals .
  • the dosing of the antifouling medium or the mixture of multiple antifouling media at intervals is preferably repeated inside a time interval of from a few hours to several days for a wanted concentration of effective medium to be re-established in the water.
  • the total treatment time is preferably extended over a time of from one to several days .
  • the heat exchanger installation is preferably integrated in a regasification plant for natural gas.
  • the regasification plant is located on a floating installation or alternatively on a fixed installation offshore or alternatively on a fixed shore-based installation.
  • the storage tank is preferably located on a fixed shore-based or offshore-based installation or on a floating installation.
  • Fig. 1 shows a simplified flow diagram for a heat exchanger installation according to the invention.
  • a heat exchanger installation 1 is provided with multiple heat exchangers Vl-V4 supplying energy to a process plant requiring heat (not shown) .
  • the heat energy source is water being pumped by the main pumps Pl-P4 from a reservoir, e.g. sea, fjord, lake, river (not shown) .
  • Multiple intake filters S1-S8 are provided on the suction side of the pumps P1-P4 for coarse filtration of the water.
  • Fine filters F1-F4 are provided on the pressure side of the pumps P1-P4 for removal of fine particles from the water.
  • the water is released to the reservoir via outlets Wl-W2.
  • the water circulation loops can be controlled by a series of valves WV.
  • a pipeline network M is arranged to lead the water .
  • the circulation pumps P5-P6 are also connected to a piping network SV arranged for connection to a storage tank S for used treatment water containing antifouling residue and decomposition products from the treatment process.
  • the circulation pumps P5-P6 are typically arranged to circulate 250-300 m 3 of treatment water over a period of several hours .
  • the piping network C for supply of antifouling medium and the piping network E for transfer of used treatment water between the heat exchanger installation 1 and the storage tank S are, for the sake of clarity, drawn in dotted line, while the ordinary circulation net in the heat exchanger installation 1 is drawn in solid line .
  • the water that is enclosed inside the heat exchanger installation 1 is used for forming treatment water by adding antifouling medium to this water .
  • valves AV connecting the piping networks C, D, E and M are opened.
  • a prescribed amount of antifouling medium is by means of the antifouling medium plant A dosed into the heat exchanger installation 1 through the piping network C, and the circulation pumps P5-P6 circulates the mixture of water and antifouling medium (also called treatment water) through the main pumps P1-P4, the fine filters F1-F4, the heat exchangers Vl-V4 and the piping network M, D and E.
  • the water enclosed in the heat exchanger installation 1 is first evacuated.
  • the water, not containing antifouling medium, is pumped into the water source.
  • the storage tank S is subsequently connected to the heat exchanger installation 1 via the piping network SV and a prescribed amount of treatment water is pumped into the circulation loop of the heat exchanger installation 1.
  • a prescribed amount of antifouling medium is thereafter added as described above .
  • the treatment water is subsequently circulated in a prescribed period. Additional antifouling medium is dosed into the treatment water at certain intervals to maintain a desired concentration of antifouling medium in the treatment water since the antifouling medium is decomposed during the treatment .
  • Antifouling medium sodium hypochlorite
  • Antifouling medium concentration ....5 ppm
  • the used treatment water is pumped into the storage tank S via the piping network SV, and the heat exchanger installation is subsequently filled with water from the water source, and ordinary water circulation for heat exchanging is started by means of prescribed operation of valves and pumps .
  • a natural gas terminal there will typically be multiple regasification units to ensure a uniform supply of gas, e.g. when a first ship is emptied and discharging from a second ship is started.
  • the treatment of a regasification unit heat exchanger installation may then be carried out in the period whilst the one regasification unit is not in operation pending the second ship to be emptied and discharging from a third ship to be started. This period is long enough for the treatment according to the invention to be completed.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Hydrology & Water Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Heat Treatment Of Water, Waste Water Or Sewage (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)

Abstract

A method for at least moderating growth of biological material in a heat exchanger installation (1) arranged to be able to circulate water through piping networks (C, D, E, M, SV) , valves (W, AV) and at least one evaporator (V1-V4) and where water, especially sea water, is a heat energy source, wherein the method comprises the following steps: a) isolating a circulation loop through the heat exchanger installation for the water being the heat energy source from the water source by closing inlets (S1-S8) and outlets (W1-W2) ; b) dosing one antifouling medium or a mixture of multiple antifouling media at intervals into the water in the enclosed circulation loop (P1-P4, M, V1-V4) and thus forming treatment water ; c) circulating the treatment water in the enclosed circulation loop (P1-P4, M, V1-V4); d) pumping the treatment water out of the circulation loop (P1-P4, M, V1-V4) and into a storage tank (S); and e) opening inlets (S1-S8) and outlets (W1-W2) of the circulation loop (P1-P4, M, V1-V4) for supply of water from the water source.

Description

A METHOD FOR PREVENTING GROWTH OF BIOLOGICAL MATERIAL IN A WATER-BASED HEAT EXCHANGER SYSTEM
The invention relates to a system for preventing or limiting growth of biological material in a water-based heat exchanger system, more exactly to prevent or moderate growth, i.e. growth of algae, mussels etc., in seawater flowlines and the like in a heat exchanger installation utilising water as the heat energy source .
It is a known phenomenon that biological material like algae, mussels etc., exhibits strong growth on installations in water, e.g. on ships, quay structures and offshore installations. Such growth in seawater flowlines may lead to greatly reduced transport capacity. The problem may become even more evident in heat exchangers utilising seawater as the heat energy source since the heat transfer capacity can be considerably reduced.
It is also known that various chemicals moderates or prevents such growth. A well-known means is ship-bottom paint coated on those parts of a ship being below the water line. Sodium hypochlorite is an example of an antifouling medium that is added to water flowing through an installation.
Use of chemicals will as a rule result in the environment close to the installation, to a lesser or greater degree, be- ing undesirably affected. In connection with a seawater based heat exchanger having a large flow rate, for example 20,000 m3/h, a continuous addition of chemicals to the water flow will give a large consumption of chemicals being spread out in a limited area by the very fact that a heat , exchanger is essentially stationary.
The object of the invention is to remedy or reduce at least one of the disadvantages of the prior art.
The object is achieved by features stated in the below description and the following claims.
The invention relates to a method for at least to moderate growth of biological material in a heat exchanger installation that is arranged to be able to circulate water through conduits, valves and at least one evaporator and where water, especially seawater, is a heat energy source, the method comprising the steps of:
a) isolating a circulation loop through the heat exchanger installation for the water being the heat energy source, by closing inlets and outlets;
b) dosing one antifouling medium or a mixture of multiple antifouling media at intervals into the water in the closed circulation loop and forming treatment water;
c) circulating the treatment water in the closed circulation loop;
d) pumping the treatment water out of the circulation loop and into a storage tank; and
e) opening the circulation loop inlets and outlets for supply of water from the water source. Repeated treatment of the water preferably includes the steps of:
f) isolating the heat energy source water circulation loop from the water source by closing the inlets and outlets;
g) pumping the water contained in the circulation loop out of the circulation loop;
h) pumping the treatment water from the storage tank and into the circulation loop;
i) dosing the antifouling medium or the mixture of multiple antifouling media at intervals into the treatment water in the closed circulation loop to form a prescribed concentration of antifouling medium in the treatment water in the circulation loop;
j ) circulating the treatment water in the closed circulation loop;
k) pumping the treatment water out of the circulation loop and into the storage tank; and
1) opening the circulation loop inlets and outlets for supply of water from the water source.
The antifouling medium is preferably added at least at the at least one evaporator.
The antifouling medium being added is adapted to the existing flora and fauna in the water being utilised as heat energy source, as a relevant field professional person will choose one or more suitable antifouling media in a suitable concentration based on knowledge of the water characteristics and the antifouling properties towards the unwanted organisms. The antifouling medium is, as an example, a metal based chemical compound or a gas. An example of a metal-based compound is sodium hypochlorite. An example of a gas is ozone.
The dosing of the antifouling medium or the mixture of multiple antifouling media to the water is made continuously or at intervals .
The dosing of the antifouling medium or the mixture of multiple antifouling media at intervals is preferably repeated inside a time interval of from a few hours to several days for a wanted concentration of effective medium to be re-established in the water.
The total treatment time is preferably extended over a time of from one to several days .
The heat exchanger installation is preferably integrated in a regasification plant for natural gas.
The regasification plant is located on a floating installation or alternatively on a fixed installation offshore or alternatively on a fixed shore-based installation.
The storage tank is preferably located on a fixed shore-based or offshore-based installation or on a floating installation.
The storage tank is preferably located on an installation being movable relative to the heat exchanger installation.
In the following a description of a non-limiting example of a preferred embodiment as visualized on accompanying drawing is given, where :
Fig. 1 shows a simplified flow diagram for a heat exchanger installation according to the invention. Reference is made to the figure where a heat exchanger installation 1 is provided with multiple heat exchangers Vl-V4 supplying energy to a process plant requiring heat (not shown) . The heat energy source is water being pumped by the main pumps Pl-P4 from a reservoir, e.g. sea, fjord, lake, river (not shown) . Multiple intake filters S1-S8 are provided on the suction side of the pumps P1-P4 for coarse filtration of the water. Fine filters F1-F4 are provided on the pressure side of the pumps P1-P4 for removal of fine particles from the water. The water is released to the reservoir via outlets Wl-W2. The water circulation loops can be controlled by a series of valves WV. A pipeline network M is arranged to lead the water .
An antifouling medium plant A arranged to form, mix and/or dose an antifouling medium or a mixture of multiple antifouling media is connected to a piping network C for supply of antifouling medium to heat exchangers Vl-V4 in the heat exchanger installation 1 via multiple valves AV (shown as smaller in size than the valves WV controlling circulation of water during ordinary running of the heat exchangers) . A piping network D further connects the heat exchangers Vl-V4 to circulation pumps P5-P6 for treatment water, the main pumps P1-P4 and the fine filters F1-F4 for circulation of treatment water containing a prescribed concentration of antifouling medium within the heat exchanger installation 1.
The circulation pumps P5-P6 are also connected to a piping network SV arranged for connection to a storage tank S for used treatment water containing antifouling residue and decomposition products from the treatment process.
While the main pumps P1-P4 are arranged for a water supply of typically 20,000 mVhour for a heat exchanger installation for a regasification plant for natural gas, the circulation pumps P5-P6 are typically arranged to circulate 250-300 m3 of treatment water over a period of several hours .
The piping network C for supply of antifouling medium and the piping network E for transfer of used treatment water between the heat exchanger installation 1 and the storage tank S are, for the sake of clarity, drawn in dotted line, while the ordinary circulation net in the heat exchanger installation 1 is drawn in solid line .
When the heat exchanger installation 1 requires treatment, stopping the main pumps P1-P4 stops the flow of water. The valves WV at the inlet filters S1-S8 and between the heat exchangers Vl-V4 and the outlets Wl-W2 are closed. A volume of water is now isolated from the water source by being enclosed inside the heat exchanger installation 1.
At the initial treatment of the heat exchanger installation 1 with antifouling medium or when there is no access to used treatment water from the storage tank S, the water that is enclosed inside the heat exchanger installation 1 is used for forming treatment water by adding antifouling medium to this water .
The valves AV connecting the piping networks C, D, E and M are opened. A prescribed amount of antifouling medium, is by means of the antifouling medium plant A dosed into the heat exchanger installation 1 through the piping network C, and the circulation pumps P5-P6 circulates the mixture of water and antifouling medium (also called treatment water) through the main pumps P1-P4, the fine filters F1-F4, the heat exchangers Vl-V4 and the piping network M, D and E.
On access to used treatment water from the storage tank S, via the piping network SV, the water enclosed in the heat exchanger installation 1 is first evacuated. The water, not containing antifouling medium, is pumped into the water source. The storage tank S is subsequently connected to the heat exchanger installation 1 via the piping network SV and a prescribed amount of treatment water is pumped into the circulation loop of the heat exchanger installation 1. A prescribed amount of antifouling medium is thereafter added as described above .
The treatment water is subsequently circulated in a prescribed period. Additional antifouling medium is dosed into the treatment water at certain intervals to maintain a desired concentration of antifouling medium in the treatment water since the antifouling medium is decomposed during the treatment .
A typical treatment process may be as follows:
Antifouling medium: sodium hypochlorite
Antifouling medium concentration: ....5 ppm
Treatment water volume: 300 m3
Dosing interval : 10 hours
Antifouling consumption:
At 50 hours treatment period: ....7.5 kg At 100 hours treatment period: ...15.0 kg
When the treatment is finished, the used treatment water is pumped into the storage tank S via the piping network SV, and the heat exchanger installation is subsequently filled with water from the water source, and ordinary water circulation for heat exchanging is started by means of prescribed operation of valves and pumps .
At a natural gas terminal, there will typically be multiple regasification units to ensure a uniform supply of gas, e.g. when a first ship is emptied and discharging from a second ship is started. The treatment of a regasification unit heat exchanger installation may then be carried out in the period whilst the one regasification unit is not in operation pending the second ship to be emptied and discharging from a third ship to be started. This period is long enough for the treatment according to the invention to be completed.

Claims

C L A I M S
1. A method for at least to moderate development of biological growth in a heat exchanger installation (1) arranged to be able to circulate water through piping networks (C, D, E, M, SV) , valves (WV, AV) and at least one evaporator (V1-V4) , and where water, particularly sea water, is a heat energy source, c h a r a c t e r i z e d i n that the method comprises the following steps: a) a circulation loop through the heat exchanger installation for the water being the heat energy source, is isolated from the water source by closing inlets (S1-S8) and outlets (W1-W2); b) one antifouling medium or a mixture of multiple antifouling media is dosed into the water in the enclosed circulation loop (P1-P4, M, Vl-V4) at intervals thus forming treatment water; c) the treatment water is circulated in the enclosed circulation loop (P1-P4, M, V1-V4) ; d) the treatment water is pumped out of the circulation loop (P1-P4, M, Vl-V4) and into a storage tank S; and e) the circulation loop (P1-P4, M, V1-V4) inlets (S1-S8) and outlets (W1-W2) are opened for supply of water from the water source .
2. A method according to claim 1, c h a r a c t e r i z e d i n that repeated treatment includes the steps of: f) isolating the circulation loop (P1-P4, M, V1-V4) for the heat energy source water from the water source by closing inlets (S1-S8) and outlets (Wl-W2); g) pumping out the water contained in the circula- tion loop (P1-P4, M, Vl-V4) from the circulation loop (P1-P4, M, Vl-V4) ; h) pumping treatment water from the storage tank (S) into the circulation loop (P1-P4, M, V1-V4) ; i) dosing the antifouling medium or the mixture of multiple antifouling media into the water in the enclosed circulation loop (P1-P4, M, Vl-V4) at intervals to form a prescribed concentration of antifouling medium in the treatment water in the circulation loop (P1-P4, M, Vl-V4) ; j ) circulating the treatment water in the enclosed circulation loop (P1-P4, M, V1-V4) ; k) pumping the treatment water out of the circulation loop (P1-P4, M, Vl-V4) and into the storage tank (S) ; and
1) opening the circulation loop inlets (S1-S8) and outlets (W1-W2) for supply of water from the water source.
3. A method according to claim 1, c h a r a c t e r i z e d i n that the antifouling medium is at least supplied at the at least one evaporator (V1-V4) .
4. A method according to claim 1, c h a r a c t e r i z e d i n that the antifouling medium is a metal based chemical compound or a gas .
5. A method according to claim 1 or 2 , c h a r a c t e r i z e d i n that the dosing of the antifouling medium or the mixture of multiple antifouling media to the water takes place continuously or at intervals .
6. A method according to claim 1 or 2 , c h a r a c t e r i z e d i n that the addition of the antifouling medium or the mixture of multiple anti- fouling media at intervals is repeated within a time interval of from a few hours to several days .
7. A method according to claim 1, c h a r a c t e r i z e d i n that the total treatment time extends over a time period of from one to several days .
8. A method according to claim 1, c h a r a c t e r i z e d i n that the heat exchanger installation (1) is integrated in a regasification plant for natural gas .
9. A method according to claim 1, c h a r a c t e r i z e d i n that the regasification plant is located on a floating or fixed installation offshore or on a fixed land based installation.
10. A method according to claim 1, wherein the storage tank (S) is located on a fixed land based or offshore- based installation or on a floating installation.
11. A method according to claim 10, c h a r a c t e r i z e d i n that the storage tank (S) is located on an installation being movable relative to the heat exchanger installation (1) .
PCT/NO2006/000339 2005-10-05 2006-10-04 A method for preventing growth of biological material in a water-based heat exchanger system WO2007040407A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO20054577 2005-10-05
NO20054577A NO329277B1 (en) 2005-10-05 2005-10-05 Process for preventing the development of biological material in a water-based heat exchanger system

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WO2007040407A1 true WO2007040407A1 (en) 2007-04-12

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1351322A (en) * 1970-07-02 1974-04-24 Sterling Drug Inc Process for conditioning sewage sludge
JPH01300196A (en) * 1988-05-27 1989-12-04 Toshiba Corp Cleaning of titanium made condenser cooling tube
JPH05215491A (en) * 1992-02-05 1993-08-24 Kubota Corp Heat exchanger for water heat source
JPH07294184A (en) * 1994-04-25 1995-11-10 Kubota Corp Ozone sterilization device in plate type heat exchanger
JPH10300389A (en) * 1997-04-25 1998-11-13 Toshiba Corp Device for preventing biological fouling of heat-exchanger
WO2001090001A1 (en) * 2000-05-19 2001-11-29 Watermaid Pty. Ltd. Cooling tower maintenance

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1351322A (en) * 1970-07-02 1974-04-24 Sterling Drug Inc Process for conditioning sewage sludge
JPH01300196A (en) * 1988-05-27 1989-12-04 Toshiba Corp Cleaning of titanium made condenser cooling tube
JPH05215491A (en) * 1992-02-05 1993-08-24 Kubota Corp Heat exchanger for water heat source
JPH07294184A (en) * 1994-04-25 1995-11-10 Kubota Corp Ozone sterilization device in plate type heat exchanger
JPH10300389A (en) * 1997-04-25 1998-11-13 Toshiba Corp Device for preventing biological fouling of heat-exchanger
WO2001090001A1 (en) * 2000-05-19 2001-11-29 Watermaid Pty. Ltd. Cooling tower maintenance

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN *

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NO329277B1 (en) 2010-09-27
NO20054577L (en) 2007-04-10

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