Background of ship ballast water management for ballast systems

Ship ballast water ballast discharge in China needs to go through a ballast water treatment system. The ship ballast water treatment system is a device for treating the ballast water discharged into the sea by the ship. Because the uncontrolled discharge of ballast water from ships is known to cause serious harm to marine ecology and public health, the International Maritime Organization (IMO) has formulated the International Convention for the Control and Management of Ballast Water and Sediments from Ships to control the discharge of ballast water from ships.

The Convention "imposes mandatory requirements on shipowners and shipowners, forcing shipowners and shipmasters to retrofit existing ship ballast water systems. For shipbuilding enterprises, higher requirements are put forward in terms of technology and safety. At the same time, it also provides a good opportunity for the current sluggish ship repair market.

Ballast water treatment is mainly aimed at preventing biological contamination.

Ballast is an inevitable state in the navigation of ships that are not allowed to discharge ballast water at a certain distance from the port in area A. When the ship is loaded with ballast water, the organisms in the seawater are also loaded into the ballast tanks until they are discharged to the destination sea area at the end of the voyage. Ballast water follows ships from one place to another, causing the spread of harmful aquatic organisms and pathogens.

Uncontrolled discharge of ballast water can cause harm to marine ecosystems, socio-economic and public health.

Generally speaking, the treatment process of ballast water is divided into three steps: "filtration", "electrolysis of seawater to produce sodium hypochlorite sterilization", and "neutralization".

In the ballast water treatment system, there are two important links: first, overtreatment filtration, and second, water treatment and sterilization. Among them, water treatment filters are selected for water treatment filtration, among which the automatic differential pressure filter of Qinhuangdao Century Water Treatment Technology Co., Ltd. has been purchased by many companies in China's certified water treatment system, and the Century Source automatic ballast water filter is a network filter, corrosion-resistant materials, and is specially designed for treating seawater.

The ballast water system is mainly composed of two high-power ballast pumps and other corresponding pipelines and valves, which must be ballasted from time to time to maintain the balance of the ship during the loading and unloading process. In modern ships, there is an automatic ballast water system on the bridge bridge, usually in the office of the chief officer, when the ballast water is discharged, the first officer notifies the engine room through the internal ** of the ship, starts the ballast pump, and the chief officer can carry out the corresponding operation after the start is arranged. In conclusion, the ballast water system is unique in its role in maintaining the balance of the ship.

Ballast water is seawater, and there are seawater pumps on board to pump seawater into the ballast tanks.

The main functions of ballast water are as follows:

1.Maintain a certain depth of draft when the ship is unladen to avoid capsizing;

2.In the state of the ship's cargo loading, ballast water can also be used to ballast and adjust between the ballast tanks to determine a certain draft difference or flat draft (the draft difference between the front and rear is 0) to ensure the smooth and safe navigation of the ship in specific waters;

3.The icebreaker uses a high-power pump to quickly adjust the ballast water at both ends of the bow and stern, and then makes the bow and tail ends move high and low, cut off the ice on the sea surface, and carry out icebreaking operations, which is also the working principle of the icebreaker.

Generally, the ballast tanks of ships are under the cargo hold, and in the space on the bottom shell of the ship, the bow and tail tanks can also be used as ballast tanks. Some ships will design special ballast tank positions according to their own navigation area and special role.

It is to ensure the ship's draft and balance, and inject seawater or river water into the ballast tank.

I'm in ship design, stability and stability, including the writing of the Ship Ballast Water Management Manual.

The key to ballast water discharge depends on the actual loading situation on the ship, and the discharge steps are different under different loading conditions, and there is no fixed step.

If it is a voyage discharge, it is generally good to pay attention to the following points:

1.Ballast water discharge affects the strength of the hull, and the shear force and bending moment must not be exceeded.

2.Ballast water discharge causes changes in draft, pay attention to cab visibility, propeller immersion, minimum draft forward and emergency fire pump suction

However, if ballast water is discharged in a port, it is basically only necessary to pay attention to the impact of structural strength.

The precautions mentioned above can generally be calculated through the ship's stowage meter, and you can also refer to the ship's "ballast water management manual" and "stability manual".

The ship's ballast water system is mainly composed of ballast water pumps, ballast water pipelines, ballast tanks and related valves, and the functions of the system are: according to the needs of ship operation, the ballast tank of the whole ship is injected or discharged, so as to achieve the adjustment of the ship's draft and the longitudinal and horizontal stability of the hull and the safe and stable center height; Reduce the deformation of the hull to avoid excessive bending moment and shear force, and reduce the vibration of the hull; The purpose of improving the airworthiness of empty cabins.

In 2004, the International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ships' Ballast Water and Sediments, which aims to prevent the invasion of alien species caused by the discharge of ballast water from ships and the damage to the environment, human health, property and resources caused by the spread of pathogens. The Convention stipulates that from 2009 onwards, new ships must be equipped with ballast water treatment equipment, and existing ships will be retrospective, and by 2017, all ocean-going ships must be equipped with ballast water treatment equipment. Otherwise, after the entry into force of the Convention, it will not be able to sail into the ports of IMO member countries, and violations of the Convention will face sanctions and penalties.

As the effective date of the Ballast Water Convention approaches, countries around the world are stepping up research and development of ballast water treatment technologies for ships. Up to now, there are more than 30 foreign R&D institutions, and 13 R&D institutions have obtained preliminary IMO approval, of which Sweden, Germany, South Korea and Norway have obtained final approval.

China now has a huge fleet accounting for the world's total tonnage, China is a big country in ship building and repair, has a huge market for key equipment for ships, and at the same time, the international market also contains huge potential.

The industrialization of ballast water treatment technology is not only an urgent need to protect the marine ecological environment, but also of great significance to improve the loading rate of key equipment of domestic ships and improve the core competitiveness of the shipping industry and the shipbuilding and repair industry. At the same time, it is also of great significance to the construction of the Navy's independent equipment.

Depending on the type of ship, the purpose of the ballast tank and the tonnage, the location, size and number of ballast tanks on the ship are also different.

Generally, ships can use the bow tank, tail tank, double bottom cabin, side tank, top side tank and deep tank as ballast water tank.

Cargo tankers can use cargo oil tanks and ballast tanks. 1. There are three types of pipeline layout of the ship's ballast water system: branch pipe type, general change annihilation type and pipe tunnel type.

2. The suction pipe in the ballast water tank of the ship shall have the function of adding water at the same time.

3. The ballast suction inlet of each ballast water tank should be arranged in a position conducive to the discharge of ballast water.

4. In order to meet the working characteristics of the ballast water system and simplify the pipeline, the valve box is mostly used to transfer the ballast water of each ballast water tank.

5. The ship's ballast water system should be able to transfer the ballast water of each ballast tank of the ship in, out or transfer to each other. Ballast pumps can also be used, and the outboard seawater automatically flows into the ballast water tank by the pressure difference.

The function of the ballast water system is to inject ballast water into the ballast water tank or discharge the ballast water from the ballast water tank, so as to achieve the following purposes: the ship maintains the appropriate displacement, draft, longitudinal and transverse balance of the hull under different working conditions such as navigation, entry and exit, loading and unloading and berthing, so as to maintain an appropriate center of gravity height, reduce the excessive bending moment and shear force of the hull and reduce the vibration of the hull.

The task of the ballast water system is to inject ballast water into each ballast tank through ballast water pumps, valve boxes and ballast lines, to discharge ballast water from each ballast tank and to transfer it between ballast tanks. 1) The flow of ballast water in the pipeline is "in and out", that is, it must enter the ballast tank and discharge from the ballast tank through the same ballast pipeline, so the check valve can not be set in the pipeline, but must be deployed through the shut-off valve box.

2) On large ships, in order to prevent ballast water from entering the cargo hold from the ballast water tank, the ballast water pipes are laid in the pipe lane in the double bilge. The arrangement of its suction ports in each compartment should be conducive to the discharge of ballast water.

3) When passing through the bow and stern compartments, it is best to have a gate valve that can be opened and closed on the upper deck, so as to close the gate valve immediately when the hull is being damaged at the bow and stern, so as to prevent the water outside the chord from entering the ballast slippery water system.

The International Convention on the Control and Management of Ballast Water and Their Sediments (hereinafter referred to as the Ballast Water Convention) adopted by the International Maritime Organization (IMO) in 2004 adopted the International Convention on the Control and Management of Ballast Water and Their Sediments on Ships, which stipulates that the entry into force of the Convention shall enter into force 12 months after the ratification of 30 countries, accounting for 35% of the world's merchant tonnage.