Ship's pumps: types, classification, characteristics, purpose

The history of shipbuilding with its roots goes back to ancient times - the first mention of swimming means appeared more than five thousand years ago. Then people moved along the rivers and seas on boats, driven by oarsmen. Since then, shipbuilding has made a tremendous breakthrough, and today this industry occupies a leading place in the economic and political sector of the country's development.

To date, it is generally accepted the terminology that a sea vessel is a large-sized swimming device intended for sea fishing, transporting goods or transporting passengers. A sea ship is a military swimming device. For the proper operation of any of these types of vessels, reliable operation of all elements and systems is necessary. First of all, it is required to ensure the optimal operation of the ship's pumps, because the movement of various liquids through the pipelines of the vessel is constant.

Why do we need pumps on the ship?

Initially, the pumps were created solely for lifting water. The first model of the ship's hydraulic device, designed for pumping water from the holds, was a manual piston pump. Now it is widely known as a pump engine. The introduction of steam power plants on ships provided the appearance of piston pumps with a steam drive.

Other, more modern types of hydraulic mechanisms, began to spread in shipbuilding, along with the development of technology. The huge role in the development of new pumps was played by the appearance of electric motors. Their introduction ensured an increase in the rotational speed of the device's working part and the pump's power.

Today, pumps have found wide application in all branches of the national economy. The shipbuilding area did not become an exception. Currently, all existing types of such devices are actively used in marine shipbuilding.

What is a pump?

A pump is a device designed to move liquid from the lower level to the upper one. Sometimes, with the help of this mechanism, the liquid is transported to give it a certain amount of energy or to increase the pressure. In the main systems of a sea-going ship, pumps are used almost everywhere: they are located in power plant systems, hydraulic drives, crew life support systems, etc.

Principle of operation of the pump

By converting the energy of the engine of the ship's pump into the energy of the moving fluid, these devices cause it to move in the desired direction (climb up, move horizontally or circulate inside the closed system). Creating the necessary transportation of a certain working fluid, such hydraulic devices in any case are part of the pumping system, the basic scheme of which is suitable for water supply or sanitation.

Schematic diagram of any pumping station of the vessel

As the driving mechanism in this scheme, an electric motor connected to the mains is used. The intake of working fluid originates from the lower basin and moves along the pressure pipeline line to the upper level due to energy conversion. At the same time, the energy of the working fluid passing through the pump is always greater than the energy before the pump.

The discharge head depends on the feed, power and efficiency of the device. It is the increment of the specific energy of the fluid being transported from the point of entry into the pump before it leaves. Expressed in meters, it determines the height of the lift or the travel distance of the working agent.

Main characteristics of the hydraulic device

The liquid supply is characterized by its volume per unit time. The optimum power of the pump is needed to create the required head and overcome all types of losses that are unavoidable when the liquid moves through the pipeline. The power of the pump, expressed in kW, determines the power of the drive motor and the installed capacity of the entire pumping station.

The coefficient of efficiency of the pump determines the expediency of its use when changing the basic parameters of the pumping station.

How do ship pumps

All types of pumps installed on the ship are classified according to the following characteristics:

• By the location of the drive shaft (horizontal or vertical).
• By type of drive (electric drive, turbine drive or drive from a piston mechanism). The drive mechanism of the pump can be connected directly to the drive shaft or via a gearbox. It can work autonomously or autonomously. Stand-alone pumps can operate independently of other installations, and non-autonomous (pinned) pumps are driven by the mechanism they operate.
• On the strength of the created head (low-pressure, medium-pressure or high-pressure).
• There is also a classification of the ship's pumps for the intended purpose . They may be special, general-purpose or designed to service certain units and mechanisms of the vessel or ship's power plant.

Special pumps can be used to move water to heel or trim tanks of a swimming device, for transporting liquid cargo or removing their residues from cargo compartments. With their help they can supply hot water to the washing devices of these compartments. Vessel-rescuers can be equipped with powerful water-drain pumps, and fire-fighting vessels - with fire pumps of enormous productivity.

Pumps used in equipping the main and auxiliary units of the vessel are used for the uninterrupted and efficient operation of these elements. Usually they are introduced in the engine-boiler rooms and power plants. They include: fuel-pumping, fuel, oil, nutrient, condensate, water and other types of devices.

Ship's pumps and their characteristics

Depending on the principle of operation, there are volumetric pumps - blade, gear, screw. Pumps can be centrifugal or jet. They can be classified by purpose and type of use. For example, there are pumps ballast, bilge, nutrient (used to supply oil or water to the cooling system), fire, pressure and others. The essence of the operation of volumetric pumps is the periodic supply of a separate amount of working fluid from the suction chamber to the compression chamber.

The simplest volumetric hydraulic mechanisms are rotary-piston pumps. Reciprocating pumps are commonly used in general ship systems, hydraulic drive deck machinery and mechanisms, main engine system and maintenance of steering machines.

Centrifugal pumps refer to devices of hydrodynamic action. The main working body in them is a rotating wheel, on which there are blades or blades. It is they who transmit the fluids necessary energy and direct the flow. These devices provide a continuous jet stream of liquid, i.e. The feed is evenly distributed. The feed of the working agent (pump output) is affected by the size of the impeller and its rotation frequency. Large impeller diameters at high speeds ensure greater hydraulic output.

Centrifugal pumps are characterized by a continuous jet stream of liquid and, consequently, uniformity of delivery. The flow rate (performance) of the pump depends on the size of the impeller and the frequency of its rotation: the larger the diameter and the speed of the impeller, the higher the pump capacity. Very often to increase the supply of liquid centrifugal pumps are performed in multi-wheeled design.

By the type of working agent's direction, the vane pumps are divided into centrifugal and axial pumps (sometimes called propeller pumps). This also includes vortex hydraulic devices. In centrifugal and vortex pumps, the working fluid can move radially, and in the axial (propeller) pumps along the axis of the shaft.

In jet pumps, energy is supplied together with the flow of the working agent (liquid or steam). The potential energy of the flow in the pump nozzle is converted into kinetic. Due to the high-speed flow of the working flow into the suction chamber, the working agent itself entrains liquid or gas from this chamber. The mixed stream moves along the discharge line through the diffuser. The ability to dry suction and create a deep vacuum can ensure the operation of the pump under water. However, the low efficiency and non-autonomy of this type of pumps are their drawback.

A jet pump designed to inject a working fluid, i.e. to increase its pressure, is called an injector. Injection pumps are often used to power steam generators of small vessels. Injectors are called jet pumps, which ensure the absorption of working fluid. They are used when removing air or condensate from any premises or units.

Kinds

A very common type of hydraulic device is a gear pump (NS). The feeder is a pair of gears in a hermetically sealed housing. When the wheels begin to rotate, the teeth that do not come into contact create an increase in volume and fluid is sucked through the lower inlet. Batch quantities of incoming liquid gradually accumulate in the space between the wheels and are forced to their outer side. So the working agent enters the compression chamber and passes into the outlet pipe. This type of ship's pumps is used for pumping viscous liquids with good lubricating characteristics, for example fuel or oil.

Screw pumps on vessels also refer to volumetric pumps. Depending on how many working elements a pump has, distinguish one-, two-, three- or multi-screw devices.

With the rotation of the drive shaft, the screw makes a complex rotational motion, in which the working fluid coming from the suction nozzle enters the inter-screw space. When the auger is turned to a certain angle, the working agent in the screw chamber is locked, as it were. The operation of the screws results in the injection of the working agent into the pressure line. If too much fluid accumulates and pressure builds up, a special safety valve opens in the compression chamber - excess liquid is discharged back into the inlet chamber.

The principle of operation of the vertical centrifugal pump of the vessel is based on the continuous supply of working fluid. The working body of the pump is a rotor with special blades fixed to the rotating drive shaft. The drive is carried out by an electric motor. When the centrifugal pump is running, the engine energy is transferred to the fluid by rotating blades. At the same time, they create the necessary pressure, under the action of which the working agent moves from input to output.

Vertical multistage centrifugal pumps are used almost everywhere, in all power plants. Multistage ship pumps are used where high pressures of working media are necessary. The principle of operation of such devices is that the liquid, having reached the necessary pressure in one stage, flows to the outlet nozzle through the next stage, where its pressure again rises.

Depending on the power, the pumps can be of different design. The huge power of the injection pumps of large-sized tankers can reach tens of thousands of tons of liquid per hour.

Purpose of the pump on the vessel

Pumps on ships are needed for pumping sea water or using them in various basic systems of a swimming device. Usually these are such general systems as:

• Fireproof.
• Desiccant.
• Cooling
• Sanitary.
• Sewer.
• Ballast.

The most important systems of swimming equipment, where different types of pumps are used

To ensure fire safety on board each ship must be a ship fire pump. Usually these units are compact and lightweight. To effectively respond to a fire and quickly locate the hearth, the pump must be quickly started. In this case, the fire pump must provide the necessary head and flow to ensure a powerful jet of water.

In the case of filling the holds with sea water, a drying pump is used. For safety requirements, there should be at least two bilge pumps on commercial or transport vessels. For passenger liners, three such pumps are necessary. And one of them should produce only dehumidification, while the other two can be used for other purposes, but they must necessarily be included in the general drainage system.

Cooling or heating systems are needed for heating or lowering the temperature of the operating fluids of ship installations. So, for example, before feeding fuel to the internal combustion engine, it must be cleaned and heated. But the lubricating oil is necessary, on the contrary, to cool. The movement of the working fluid is ensured by the operation of special pumps.

To ensure comfortable living of the crew, the ship's sanitary system is necessary. The operation of such a system is provided by sanitary pumps. With their help, there is a supply of drinking water or tap water to the bathrooms.

The ballast system serves to drain and fill the ballast tanks of the vessel with sea water.