Ballast water system

System Introduction

COSCO Blue Ocean Shield (BOS) ballast water treatment system is designed and manufactured as the requirements of International Convention for the Control and Management of Ship’s Ballast Water and Sediments, 2004, with the aim to prevent, minimize and ultimately eliminate the risks to the environment, human health, property and resources arising from the transfer of harmful aquatic organisms and pathogens through the control and management of ship’s ballast water and sediments.

Technology：

Mechanical Filter + Medium Pressure UV Disinfection (Physical Technology)

Components:

● Filter Unit: Negative Pressure Suction Self-Cleaning Filter, removes the organisms and particles greater than 50μm.

● UV Unit: Medium Pressure Disinfection Technology-effectively inactivates the aquatic nuisance species (ANS) and pathogens.

● Control Unit: One-touch operation; Automatic operation, control and monitor.

Operation Principle:

When ballasting, BOS filter removes the sediments and micro-organisms greater than 50μm. After that ballast water enters the UV reactor, appropriate dose of UV ray is generated in order to inactivate the organisms, such as algae and bacteria in the water. With the completion of above treatment, the ballast water comes to ballast tank.

When de-ballasting, the filter is automatically bypassed, and the ballast water goes directly through the UV Unit, and receives a second UV-treatment, ensuring discharged water in compliance with the convention’s requirements and USCG’s requirements.

When ballasting, BOS filter removes the sediments and micro-organisms greater than 50μm. After that ballast water enters the UV reactor, appropriate dose of UV ray is generated in order to inactivate the organisms, such as algae and bacteria in the water. With the completion of above treatment, the ballast water comes to ballast tank.

When de-ballasting, the filter is automatically bypassed, and the ballast water goes directly through the UV Unit, and receives a second UV-treatment, ensuring discharged water in compliance with the convention’s requirements and USCG’s requirements.

Filter Unit

The filtration unit comprises one or more negative pressure filters in parallel to remove the particles and plankton larger than 50um from the ballast water. When removing the larger plankton, the filter can enhance the light transmittance of ballast water for treatment and improve the efficiency of subsequent UV disinfection. Besides, the filter screen could be cleaned automatically to ensure the repetition of water treatment.

BOS filter is an automatic negative pressure filter with easy operation and advanced technology. The cleaning device is driven by a rotatory motor to complete the cleaning process.

Working Principle:

Ballast Water flows into the filter, goes through the filter screen, and exits from the Water Outlet. When the water passes through the filter screen from inside to outside, the impurities accumulate in the filter screen, resulting in the differential pressure. Once the differential pressure reaches the preset value, the self-cleaning will be started. The scanner motor starts to work, with the drain valve open and sewage pump turned on, thus removes the impurities off the filter screen, and discharges them from the duct and the drain outlet. Backwash keeps cleaning the impurities off the filter screen to maintain the filter’s sustained filtration ability, making the differential pressure stay at a low level. Backwash will not interrupt the ballasting flow.

Advantages:

● Suitable for operation in all waters, free from blockage.

● Self-cleaning assisted by negative pressure stable flow with small flow loss.

● Simple mechanical structure; continuous stable operation;

● Automatic refresh suction nozzle,better suitable in filtering solids, extending the maintenance cycle.

● Pressure drop less than 0.05MPa, ensuring system work in highly efficient state.

● Horizontal and vertical configuration, easy arrangement.

● High quality component, long service life, reliable operation.

UV Unit

BOS UV reactor uses a “criss-cross” layout design, making medium-voltage lamp perpendicular to the fluid. With the help of coupling technology of computer-aided light field and flow field, the UV reactor is compact in design and low in space occupancy. The UV reactor uses components purchased from internationally renowned manufacturers and adopts unique frequency convention technology to control the operation of equipment, so as to extend the service life of critical parts and optimize its capacity of treatment and cost.

UV reactor consists of stainless steel shell and UV lamp, from which the water flows to complete the treatment. The UV lamp is covered with quartz sleeve and installed in the UV reactor and the water flows through the sleeves from all directions.

Features:

UV light damages DNA and RNA after penetrating through cell wall and membrane of the ANS (aquatic nuisance species) and prevent its reproduction (non-viable). UV light has no second pollution, and is the safest disinfection technology for ballast water treatment. Medium voltage UV lamp has a polychromatic output at multi wavelength across the entire spectrum of the germicidal curve, more suitable for disinfecting poor quality water at high flow.

Ultrasonic cleaning technology is developed by WECOSCO, used for quartz sleeve anti-scaling and cleaning. With the advanced design and simple structure, the cleaning effect is superb and remarkable. The ultrasonic self-cleaning unit has static mechanical structure, which has no damage potential to the quartz sleeve, so it has no maintenance requirement. Through ultrasonic refraction and diffraction, ultrasonic cleaning achieves omnidirectional cleaning and leaves no dead angle, keeping all quartz sleeve away from scaling.

Advantages:

● Widely used, applicable for all waters;

● Optical field and flow field coupling technology, high efficacy of disinfection;

● Green and environment friendly, safe and reliable;

● High quality medium pressure UV light, with service time 5000h; low maintenance cost;

● Inter connection with Expansion Joint and Elastic;

● Exclusively parent right-applying the ultrasonic technology in quartz sleeve anti-scaling and cleaning;

Control Unit

Integrated control unit comprises a control system box, a remote control system box and a series of transmitters and actuators. The remote control system box is used to control the ballast water management system remotely and is optional to the customer The functions of integrated control system include: HMI, automatic control of system processes, manual control function, equipment fault record and alarm, and recording of equipment operating conditions. In the integrated control unit, the filters and UV disinfection system as well as valves in the BOS system achieve a coordinated action, ensuring continuous and stable operation of the equipment and reducing the operator’s labor intensity.

Advantages:

 International advanced PLC automatic control system, one touch operation.

 Automatic operation-data logging and displaying:

Operation Mode (ballast, de-ballast, stripping);

Working Time; Vessel’s position (GPS);

Alarm (running condition, valve status) .

 Easy shift between auto and manual operation, graded management in local control and remote control.

SCR Introduction

Selective Catalytic Reduction (SCR) technology is a means of controlling NOx emission in exhaust gas from diesel engine, which has been applied in power plant and auto industry for years. It is found that SCR technology has a wide range of application and little effect on safety of engine. It has been shown to reduce NOx by 80% to 90%, so it is considered to be the most important after-treatment method to meet Tier III and other more strict regulations on NOx emission in the future.

The NOx reduction takes place as the gases pass through the SCR reactor. NH3 is used as reducing agent. Under appropriate temperature and with the aid of catalyst, the NOx in exhaust gas from diesel engine is converted to N2 and H2O. The chemical equation for a selective catalytic reduction process is:

HNCO + 2H2O → NH3 + CO2

CO(NH2)2→ NH3 + HNCO

4NH3 + 4NO + O2 → 4N2 + 6H2O

4NH3 + 2NO2 +2NO → 4N2 + 6H2O

The SCR system developed by WECOSCO Technology, SMDERI and Sailinde Marine Technology (Wuhan) jointly adopts mature selective catalytic reduction (SCR) technology to remove NOx in the marine exhaust gas. It is featured with small size, low power consumption, high intelligence, reliable operation and muffling function. It has reached the domestic leading and internationally first-class level and obtained the type approval certificate issued by China Classification Society. On March 22, 2017, the signing ceremony of SCR system for 7500 DWT asphalt carrier was held in Shanghai. The SCR system is to be installed on four 7500 DWT asphalt carriers owned by COSCO SHIPPING Specialized Carriers Co., Ltd., which marks an important step in domestic marine environment-protection equipment industry.

Application region:

Marine diesel engine and other engines having NOX reduction requirement.

Product features:

• Efficient conversion of NOX, conversion rate≥80%, up to more than 95%, meets the requirements of IMO Tier III.
• Wide range of reaction temperature: 260℃-550℃，suitable for different exhaust temperature range.
• Strictly control the amount of escape of NH3: less than 10ppm.
• Economy: urea consumption≤21g/kW.h (40% urea solution).
• Automatic control of the whole process, precise control of reducing agent, atomization and spray processes.
• Compact and flexible design, can be customized according to customer requirements.

System Components

The SCR system is composed of a reactor unit, a feeding unit, a control unit, a urea online production unit (or urea storage unit).

1.SCR reactor

• Internally mounted catalyst.
• Fast filling structure, the catalyst can be easily filled into the reactor.
• Unique mixed flow diversion device, improve the conversion efficiency more than 8%, National invention patent license.
• With a noise reduction function, can be integrated with the muffler.

2.Feeding unit

• Realization of real time measurement and supply of urea solution in SCR system and spray atomization.
• Multi stage injection technology, precise control of the dosage of urea solution.
• Automatic purge of urea spray gun, effectively avoid the crystallization of urea.
• Multiple reactors can share a set of feeding unit, saving cost.

3.Urea storage unit

• Automatic heating of urea solution at low temperature to avoid crystallization
• Level data real-time transmission
• Low level alarm
• If the loading space in the ship is limited, the urea storage silo is far from the feeding unit. The urea daily storage tank can be installed near the feed unit.
• The tank capacity can meet the requirement of urea solution consumption for SCR system operating for more than 8 hours

4.Urea on-line preparation unit

• Automatic preparation of urea solution for SCR system using urea dry powder
• Greatly reduces the required urea storage space and ship load.
• National invention patent license has been obtained.

Note: An alternative to urea storage unit

5.Control unit

• System automation control, system monitoring, abnormal alarm.
• Advanced technology: injection error correction, urea solution concentration change compensation, independent on the engine parameters, device loss compensation correction.