Marine pumps are all kinds of pumps for ships that meet the requirements of ship regulations and marine technical requirements. On ships they are often used to transport various liquids such as seawater, fresh water, sewage, oil and fuel.
The characteristics of the marine pump are: the pump is required to be cavitation due to the fluctuation of the suction liquid surface when the ship is swaying and tilting; in order to reduce the occupied area of the pump and to facilitate maintenance, the vertical structure is generally adopted; the flow passage member is made of bronze, Made of materials such as brass or stainless steel to minimize corrosion.
Marine pumps have a wide range of applications in modern ships. Generally speaking, a diesel-powered cargo ship requires 36 to 50 pumps of various types, which accounts for 20% to 30% of the total amount of marine machinery and equipment.
A. Marine pumps can be classified according to their use:
(1) Pumps for marine power units. There are fuel pumps, lubricating oil pumps, sea water pumps, fresh water pumps, hydraulic pumps for steering gears or other deck machinery, feed pumps for boiler installations, cooling pumps for refrigeration units, sea water pumps for seawater desalination units, and condensate pumps.
(2) General purpose pump for ships. There are bilge pumps, ballast pumps, fire pumps, daily fresh water pumps, daily sea water pumps, hot water circulation pumps; and general-purpose pumps that also serve as ballast, fire, and bilge pumps.
(3) Special ship special pumps. Certain special-purpose ships also have special pumps for their special operational requirements, such as cargo pumps for oil tankers, mud pumps for dredgers, salvage pumps for salvage vessels, and water jet propulsion pumps for waterjet propulsion vessels. Fishing pumps on net fishing boats, etc.
B. According to the working principle of the pump, the marine pump mainly has the following types:
(1) Positive displacement pump
The positive displacement pump draws and discharges liquid by periodically increasing and decreasing the working volume caused by the movement of the working part. When the working volume is increased and the pressure is lowered, the liquid is sucked in. When the working volume is decreased and the pressure is increased, the liquid is discharged and squeezed. The pressure directly increases the pressure of the liquid. According to the different movement modes of the moving parts, it can be divided into two types: reciprocating pump and rotary pump. The former has a piston pump and a plunger pump; the latter has a gear pump, a screw pump, a vane pump, and the like.
(2) Impeller pump
The impeller pump is driven by the impeller to move the liquid at high speed, continuously generating the suction and discharge function, transferring the mechanical energy to the delivered liquid, increasing the pressure energy of the liquid and achieving the purpose of conveying the liquid. According to the characteristics of the impeller and runner structure of the pump, it can be divided into centrifugal pump and vortex pump.
(3) Jet pump
The jet pump generates a high-speed jet ejector fluid in a nozzle by a working fluid having a certain pressure, and then increases the energy of the ejector fluid by momentum exchange. According to the working fluid used, it can be divided into water jet pump, steam jet pump and air jet pump.
In addition to classification according to the working principle, the pump can also be divided into vertical pump and horizontal pump according to the position of the pump shaft; divided into single suction pump and double suction pump according to the number of suction nozzles; , steam pumps and diesel pumps. Generally, the ship is named after the pump according to the function of the pump, such as the host seawater cooling pump and the main engine oil pump.
