GB2524403A

GB2524403A - Ballast water treatment system

Info

Publication number: GB2524403A
Application number: GB1504766.5A
Authority: GB
Inventors: Robert Field; Matthias Voist
Original assignee: Cathelco Ltd
Current assignee: Cathelco Ltd
Priority date: 2014-03-21
Filing date: 2015-03-20
Publication date: 2015-09-23
Anticipated expiration: 2035-03-20
Also published as: GB2524403B; GB201504766D0; GB201405106D0

Abstract

A ballast water treatment system 14 defines a flow path 20 having an inlet 16 for receiving ballast water and an outlet 18 for discharging ballast water. An ultraviolet (UV) reactor 24, having one or more UV lamp(s) 40, is arranged in the flow path so that ballast water is exposed to UV radiation when flowing through the UV reactor. The UV reactor is configured to induce helical flow of the ballast water around the, or each, UV lamp. A sampling system 30, upstream of the UV reactor and downstream of a filter 22, is configured to divert a sample of ballast water from the flow path to a UV transmittance sensor 32. A controller (28, Fig. 3) sets and adjusts the power of the UV lamp(s) in relation to a signal from the UV transmittance sensor. A flow control valve 38 is arranged between the sampling system and the UV reactor, wherein the controller is configured to communicate with the valve to control the flow rate of ballast water en route to the UV reactor in relation to a signal from the UV transmittance sensor.

Description

Ballast Water Treatment System

FIELD OF THE INVENTION

The present invention relates to a ballast water treatment system. More particu'arly, S the present invention relates to a ballast water treatment system and a method of treating ballast water on marine vessels

BACKGROUND OF THE INVENTION

Cruise ships, large tankers, and bulk cargo carriers use marine water as a ballast to provide increased stability. Water is often taken on in one coastal region, for example after the unloading of cargo, and is then discharged in another coastal region, for example at the next port of call.

A large number of organisms and pathogens are present in sea water, and the transportation of this sea water in the ballast tank from location to location can introduce non-native species to new environments and cause the spread of harmful or invasive organisms. Due to this, it is of great importance to render organisms non-viable in the ballast water whilst it is stored on the ship prior to being discharged at a subsequent location.

Water treatment systems using chemical treatments are known in the art. However, such methods are not desirable, None-chemical treatment systems are beneficial as they ensure that no chemicals which could be harmftil to the sea environment are released into the sea. Further to this, it is beneficial to remove chemical handling from taking place on board the ship.

Water treatment systems using filtration and ultraviolet (UV) radiation are generally known in the art. However, such systems are not very energy efficient and have power consumption issues which can lead to the shortening of the lifetime of certain components of the system, for example liv lamps.

The present invention is intended to provide an improved liv ballast water treatment system.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a ballast water treatment system comprising: an inlet for receiving ballast water; an outlet for discharging ballast water; and a ballast water flow path configured for the flow of ballast water between the inlet and the outlet, wherein a IJV reactor is arranged in the ballast water flow path, the IJV reactor having one or more liv lamps arranged so that ballast water flowing through the liv reactor can be exposed to UV radiation, wherein the UV reactor is configured to induce helical flow of the ballast water around the or each UV lamp as the ballast water flows through the IJV reactor; further wherein the ballast water treatment system comprises a control system for controlling UV dosage within the reactor, the control system comprising a controller and a sampling system, the sampling system being arranged upstream of said UV reactor and configured for diverting a sample of ballast water from the ballast water flow path to a liv transmittance sensor prior to passing through the UV reactor; wherein a ballast water filter is arranged between said inlet and said sampling system; and further wherein the controller is configured for setting and adjusting the power of the or each IJV tamp in relation to a signal from the IJV transmittance sensor, in order to affect the UV dosage for the ballast water passing through the UV reactor, and a flow control valve is arranged between the sampling system and the UV reactor, wherein the controller is arranged in communication with the flow control valve and is n j configured to control the flow rate of ballast water en route to the UV reactor in relation to a signal from the TJV transmittance sensor.

The ballast water system in accordance with the invention advantageously sets the power of the or each IJY lamp to an optimal level on start-up of the system which economises the power consumption of the or each IJY lamp, and as a result extends the lifetime of the or each UV lamp.

In known water treatment systems, the IJY lamps are set to maximum power at start-up and subsequently adjusted down if a change in quality of water entering the system is detected. This results in unnecessary power consumption at start-up if the maximum power value of the TJV lamp is greater than the optimal power required by the UV lamp to apply the required dosage. In addition, the unnecessary power consumption is exacerbated if there is no change in the water quality entering the system during the ballast water treatment process.

Advantageously, by means of the ballast water treatment system of the invention, the controller, based on input from the UV transmittance sensor, can optimise the exposure time by adjusting the flow rate using the flow control valve if the dose rate cannot be achieved through normal flow. As a result, the UV reactor of the ballast water treatment system of the present invention may have a lower number of UV lamps than systems known in the art for the same capacity, and hence a smaller footprint which is particularly suited for installing in confined areas within marine vessels, such as within an engine room, and is beneficial in economising space.

In addition, the ballast water treatment system in accordance with the invention, due to the sampling system, aflows for automatic adjustment of the applied liv dosage, which allows the system to adjust for different qualities of sea water with higher or lower sediment loads.

Moreover, the ballast water treatment system of the invention allows for precise control of TJV dosage throughout the ongoing transfer of water into the baflast tank should there be a change in the quality of water being transferred, This ensures maximum effectiveness of the liv treatment process, whilst economising on power consumption as well as extending the life of the UV lamp.

Furthermore, inducing helical flow of the ballast water maximizes the exposure of the water to liv radiation.

Preferably, the control system is configured to control UV dosage within the reactor using the following formula: Dosage =l6O(mDeT)X Exposure timeX 0.15 K 0.95 X 10000 K UVT % at 32 mm wherein Exposure time = (Flow rate 0935) X 156.8, UVT % at 32mm = UVT conversion value32, IJVT%atlOmni UVT conversion value = UVT % at 10mm = 100 -10sccthemput, and Scale input = said signal from the liv transmittance sensor in mA scaled by a factor of 0.00025.

In exemplary embodiments, the water treatment system comprises first and second liv reactors in series and arranged side-by side, each including a liv chamber having an elongate lamp, and each configured for inducing helical flow of ballast water around said lamp.

In preferred embodiments, the liv chamber further comprises a UV intensity meter.

Advantageously, this can be configured to allow for constant monitoring of the liv lamp, e.g. to identify when the lamp is faulty or needs replacing.

Preferably, the filter is configured to prevent anything larger than 40 microns to pass through, In exemplary embodiments, the ballast water treatment system further comprises a discharge bypass in the flow path configured to redirect the flow of ballast water in order to circumvent the ballast water filter. This allows the system to be re-mn at a faster rate during discharging of the ballast tank than the filling of the ballast tank.

This is beneficial where the ballast water is treated for a second time prior to discharge to reduce the risk of any re-growth of ay contamination during storage in the ballast tank.

According to a second aspect of the present invention, there is provided a method of treating ballast water comprising the following steps: causing ballast water to flow along a ballast water treatment flow path including a liv reactor fitted with one or more liv lamps, so that the ballast water is exposed to liv radiation as it flows through the reactor; diverting a sample of ballast water to a liv transmittance sensor prior to flow through the IJV reactor; adjusting the power of the or each liv lamp in relation to a signal from the liv transmittance sensor; filtering the ballast water prior to diverting said sample; inducing a helical flow in the ballast water as it flows through the liv reactor; and controlling the flow rate of ballast water en route to the liv reactor in relation to a signal from the liv transmittance sensor.

According to a third aspect of the present invention, there is provided a method of treating ballast water comprising the steps of: causing ballast water to flow along a ballast water treatment flow path including a UV reactor having one or more UV lamps, so that the ballast water is exposed to liv radiation as it flows through the liv reactor; diverting a sample of ballast water to a liv transmittance sensor prior to flow through the UV reactor; filtering the ballast water prior to diverting said sample; to inducing a helical flow in the ballast water as it flows through the UV reactor; determining a UV dosage for the liv reactor based on a signal from the UV transmittance sensor; wherein the determined liv dosage is dependent upon UV lamp power, UV exposure time within the UV reactor and the percentage of IJY transmission at a distance of 32 mm; and tS controlling the flow rate of ballast water en route to the TJV reactor in relation to a signal from the liv transmittance sensor.

The UV dosage may be based on said signal from the UV tnmsmittance sensor and the amount of UV light at 254 Nm being measured at tO mm, Preferably, the UV dosage is determined from the following formula: Dosage =l6O(m:we?)X Exposure timeX 0.15 X 0.95 X 10000 X UVT % at 32 mm wherein Exposure time = (Flow rate _09) X 156.8, UVI % at 32mm = UVT conversion value3'2, UVT%atlomm UVT conversion value = ____________ UVT % at 10mm = 100 -1osc°e°inpttt, and Scale input = said signal from the liv transmittance sensor in mA scaled by a factor of 0.00025.

In exemplary embodiments of the second and third embodiments, the flow rate of ballast water is controlled by means of a flow control valve arranged between the sampling system and the liv reactor.

Preferably, the or each liv lamp is mounted in a liv chamber, which further comprises a UV intensity meter, the method further comprising the step of monitoring the performance of the or each UV lamp to indicate when replacement or maintenance of the or each liv lamp is necessary.

BRIEF DESCRIPTION OF THE DRAWiNGS

Embodiments of the invention will now be described with reference to the tS accompanying drawings, in which: Figure lisa schematic side view of a ship; Figure 2 is a schematic view of a ballast water treatment system in accordance with an embodiment of the invention; and Figure 3 is a block diagram showing a ballast water treatment process in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENT(S)

Referring firstly to Figure 1, a marine vessel in the form of a ship 10 has a ballast tank 12 and a ballast water treatment system 14.

The ballast water treatment system 14 is shown in more detail in Figure 2, and includes the following major elements: an inlet 16 for receiving ballast water en route to said ballast tank 12; an outlet 18 for discharging the ballast water from the system t4; a ballast water flow path 20 arranged between the inlet t6 and the outlet 18; a water filter 22; a liv reactor 24 having a liv lamp 40 arranged so that ballast water flowing through the liv reactor 24 can be exposed to liv radiation; a controller 28 for controlling the liv chamber 26; a sampling system 30 having a liv transmittance sensor 32; and a flow control valve 38 for controlling the flow of water through the liv reactor 24.

As will be apparent from Figures 2 and 3, upon the uptake of sea water onto the ship to, the sea water passes through the inlet t6 into the flow path 20. The sea water then passes through the filter 22, in order to remove large organisms and sediments. In exemplary embodiments, the mesh size of the filter is 40 microns, which guarantees effective removal of suspended materials and organisms that are greater than 40 microns.

During ballast water uptake, all of the matter removed by the filter 22 is automatically discharged into the sea at the point of origin, to ensure that organisms are not transported to new locations. The filter 22 may form part of a filter unit configured with an automated back flushing process, for cleaning the filter and ensuring operation at maximum flow rates. Different filter units are available to allow for different required flow rates from 50 m3/hour to 1,200 m3/hour.

Following filtration, a sample of the ballast water is then diverted from the flow path to the sampling system 30, As can be seen, the sampling system 30 is located upstream of the UV reactor 24. The UV transmittance sensor 32 measures the light transmittance through the sample, which is indicative of the liv transmission through the water.

The ballast water then flows through a flow control valve 38, arranged and configured to enable the adjustment of the flow rate of the ballast water through the system before entering the liv reactor 24.

In the illustrated embodiment, the system includes two TJV reactors 24 in series, each including a liv chamber 26 having an elongate UV lamp 40.

Each UV reactor 24 is configured for inducing helical flow of the ballast water around the UV lamp 40 as the ballast water passes through the UV reactor 24. This has been found to improve the exposure of the ballast water to liv radiation from the lamps 40.

The two reactors 24 are arranged side-by-side, providing a smaller footprint which is particularly suited for installing in confined areas within marine vessels, such as within an engine room. The treated water can then be directed through the outlet 18 of the system 14, e.g. into the ballast tank 12.

In alternative embodiments, the system may comprise multiple reactors in parallel, and in this system an inlet manifold (not shown) is provided to distribute water correctly between the reactors.

In exemplary embodiments, the lamps 40 are medium pressure UV lamps. The broader UV spectrum emitted by these lamps allows for a more effective inactivation of organisms across a wide range of water qualities. Each UV reactor 24 is equipped with a UV intensity meter 34, for monitoring the performance of the lamps, e.g. so as to indicate when replacement is necessary, when to engage the cleaning cycle and/or whentoactivateanalarm.EachuVlamp40issecuredinaquart.ztubetoprotectthe lamp from the ballast water. This quartz tube filters out the UV radiation below 200 nm to prevent the production of ozone.

A method of operating the system will now be described by way of example, with reference to Figures 2 and 3.

In use, the controller 28 receives a signal from the sampling system 30. As will be described in more detail below, the controller 28 is configured to calculate a suitable IJV dosage for the ballast water in the flow path 20, in relation to the signal from the sampling system 30 based on the measurement from the UV transmittance sensor 32.

In exemplary embodiments, the controller 28 calculates the required TJV dosage using the IJV transmittance (UVT) measurement from the UV transmittance sensor 32, the flow rate through the reactors 24, and the lamp power.

The amount of energy required to be imparted into the ballast water by the UV lamp 40, as an output of said dosage calculation, is obtained from the input signal received from the sampling system 30 and the amount of UV light at 254 Nm being measure at 10mm. This is then scaled to 32mm as being measured at the wall of the reactor as intensity. The following is an exemplary method for calculating the required UV dosage: * A mA input signal is received from the sampling system 30.

* The input signal is then scaled by a factor of 0.00025 * The UVT at a distance of 10mm is calculated via o UVT % at 10mm = 100 -10SCnPUt * Convert TJVT from a percentage, UVT%atlOmm o IJVT conversion value = ___________ * Convert the UVT at 10 mm to a UVT at a distance of 32 mm, o UVT % at 32 mm = UVT conversion value32 * Calculate the exposure time o Exposure time = (Flow ratr°9) X 156.8 * Dosage 160(LamPPower)x Exposure timeX 0.15 X 0.95 X 10000 X UVT % at 32 mm ii Accordingly, the controller calculation can be used to determine the optimum power to be applied to the UV lamp 40, for ensuring that an accurate UV dosage is applied to the ballast water as it passes through the reactors 24. This also economises the power consumption of the UV lamp 40 (thereby extending the lifetime of the UV lamp), especially at the start-up of the system where an initial dosage value needs to be determined. In known water treatment systems, the UV lamps are set to maximum power at start-up and subsequently adjusted down if a change in quality of water entering the system is detected. This results in unnecessary power consumption at start-up if the maximum power value of the liv lamp is greater than the optimal tO power required by the liv lamp to apply the required dosage. In addition, the unnecessary power consumption is exacerbated if there is no change in the water quality entering the system during the ballast water treatment process.

The controller may also adjust the flow rate through the reactor 24 (via said flow control valve 38) in order to optimise exposure time if required, e.g. if the dose rate cannot be achieved through the normal flow. This is done by controlling the flow rate of ballast water en route to the reactor 24 in relation to a signal from the UV transmittance sensor 32.

The UV transmittance sensor 32 is configured to continuously send signals to the controller 28 relating to the quality of the water. In turn, the controller 28 is configured to send signals periodically (e.g. every 90 seconds) to adjust the flow valve 38 and!or the liv lamp 40 based upon the signals received from the UV transmittance sensor 32.

After UV treatment, the ballast water flows through the outlet 18 into the ballast tank 12. During discharging of the ballast tank, the system 14 can be re-run and bypass the filter via a discharge bypass 44. The water is treated for a second time to reduce the risk of any re-growth of any contamination during storage in the ballast tank.

Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

S

Claims

Claims 1. A ballast water treatment system comprising: an inlet for receiving ballast water; an outlet for discharging ballast water; and a ballast water flow path configured for the flow of ballast water between the inlet and the outlet; wherein a liv reactor is arranged in the ballast water flow path, the UV reactor having one or more UV lamps arranged so that ballast water flowing through the liv reactor can be exposed to tiV radiation, wherein the liv reactor is configured to induce helical flow of the ballast water around the or each liv lamp as the ballast water flows through the liv reactor; further wherein the ballast water treatment system comprises a control system for controlling UV dosage within the reactor, the control system comprising a controller and a sampling system, the sampling system being arranged upstream of said liv reactor and configured for diverting a sample of ballast water from the ballast water flow path to a liv transmittance sensor prior to passing through the UV reactor; wherein a ballast water filter is arranged between said inlet and said sampling system; and further wherein the controller is configured for setting and adjusting the power of the or each uv lamp in relation to a signal from the liv transmittance sensor, in order to affect the liv dosage for the ballast water passing through the liv reactor, and a flow control valve is arranged between the sampling system and the uv reactor, wherein the controller is arranged in communication with the flow control valve and is configured to control the flow rate of ballast water en route to the liv reactor in relation to a signal from the uv transmittance sensor.
2. A system according to claim 1, wherein the control system is configured to control liv dosage within the reactor using the following formula: Dosago 160(Lamr power)X Exposure timeX 0.15 X 0.95 X 10000 X UVT % at 32 mm la7 wherein Exposure time = (Flow rate _0985) X 156.8, UVT % at 32mm = UVT conversion value32, UVT%atlOmm UVT conversion value = ____________ / 100 IJVT ?zo at 10mm = 100 -10scczle, and Scale input = said signal from the liv transmittance sensor in mA scaled by a factor of 0.00025.
3. A system according to claim I or claim 2, wherein the water treatment system comprises first and second liv reactors in series and arranged side-by side, each including a liv chamber having an elongate lamp, and each configured for inducing helical flow of ballast water around said lamp.
4. A system according to any of claims I to 3, wherein the or each liv chamber further comprises a UV intensity meter.
5. A system according to any of claims 1 to 4, wherein the filter is configured to prevent anything larger than 40 microns to pass through.
6. A system according to any of claims I to 5 further comprising a discharge bypass in the flow path configured to redirect the flow of ballast water in order to circumvent the ballast water filter.
7. A method of treating ballast water comprising the following steps: causing ballast water to flow along a ballast water treatment flow path including a liv reactor fitted with one or more UV lamps, so that the ballast water is exposed to liv radiation as it flows through the reactor; diverting a sample of ballast water to a liv transmittance sensor prior to flow through the UV reactor; adjusting the power of the or each liv lamp in relation to a signal from the liv transmittance sensor; filtering the ballast water prior to diverting said sample; inducing a helical flow in the ballast water as it flows through the liv reactor; and controlling the flow rate of ballast water en route to the liv reactor in relation to a signal from the UV transmittance sensor.
8. A method of treating ballast water comprising the steps of causing ballast water to flow along a ballast water treatment flow path including a UV reactor having one or more UV lamps, so that the ballast water is exposed to liv radiation as it flows through the liv reactor; diverting a sample of ballast water to a liv transmittance sensor prior to flow through the liv reactor; filtering the ballast water prior to diverting said sample; inducing a helical flow in the ballast water as it flows through the liv reactor; determining a liv dosage for the liv reactor based on a signal from the liv transmittance sensor; wherein the determined liv dosage is dependent upon liv lamp power, UV exposure time within the liv reactor and the percentage of UV transmission at a distance of 32 mm; and controlling the flow rate of ballast water en route to the liv reactor in relation to a signal from the liv transmittance sensor.
9. A method according to claim 8, wherein said uv dosage is based on said signal form the U'V transmittance sensor and the amount of uv light at 254 Nm being measured at 10mm.
10. A method according to claim 9, wherein said uv dosage is determined from the following formula: Dosage =l6O(m 0wC1)X Exposure timeX 0.15 X 0.95 K 10000 K UVT % at 32 mm wherein Exposure time = (Flow rate _095) X 156.8, UVT % at 32mm = UVT conversion value32, UVT%atlUmm UVT conversion value = ____________ IJVT % at 10mm = 100 -, and Scale input = said signal from the IJV transmittance sensor in mA scaled by a factor of 000025.
11. A method according to any one of claims 7 to 10, wherein the flow rate of ballast water is controlled by means of a flow control valve arranged between the sampling system and the UV reactor.
12. A method according to any one of claims 7 to 11, wherein the TJV lamp is mounted in a UV chamber, which further comprises a UV intensity meter, the method further comprising the step of monitoring the performance of UV lamp to indicate when replacement or maintenance of the UV lamp is necessary.