Do you know what types of cargo pumps are available?

Due to the different sizes of oil tankers, the different types of oil loaded, and the specific conditions of each oil tanker, the requirements for cargo oil pumps are different. Therefore, there are many types of cargo oil pumps used by oil tankers.
If divided by the pump itself, there are three main types: reciprocating cargo pump, centrifugal cargo pump, vane cargo pump;
If divided by power machine, there are four main types: steam direct acting cargo pump, steam turbine cargo pump, electric motor cargo pump, and diesel engine cargo pump.
Cargo pumps mainly include: steam direct acting reciprocating cargo pumps, steam turbine centrifugal cargo pumps, and motor centrifugal cargo pumps. Some oil tankers also use diesel centrifugal cargo pumps or motor vane cargo pumps.
1. Steam direct acting reciprocating cargo pump
This is a steam powered pump whose cylinder piston rod is directly connected to the cylinder piston rod. The steam piston is driven by steam to reciprocate, directly driving the oil piston to reciprocate, so it is called a steam direct acting reciprocating pump.
This cargo pump has the following advantages:
1) Safe and reliable. Because this is a steam powered pump that does not require superheated steam, it is very advantageous for the fire and explosion protection of oil tankers, and can be arranged anywhere without considering fire and explosion protection measures.
2) It can create a high vacuum and maximize the suction of cargo oil at the bottom of the cargo oil tank. Therefore, it can be used instead of a tank sweeping pump, which allows oil tankers equipped with steam direct acting reciprocating pumps to be equipped without additional tank sweeping pumps.
3) The displacement is easy to adjust. Due to the characteristics of the steam direct acting structure, it is easy to adjust the displacement. As long as the opening of the steam inlet valve is changed, the pressure and flow of steam entering the cylinder will change accordingly, resulting in changes in the number of strokes of the steam piston and the oil piston, making it easy to achieve displacement adjustment.
4) Simple structure, low cost, convenient management, and easy maintenance.
However, this type of cargo pump has a relatively low efficiency and its displacement is limited by its volume and weight, making it difficult to manufacture pumps with large displacement.
2. Turbine centrifugal cargo oil pump
Using a steam turbine to drive a centrifugal pump, a steam turbine centrifugal pump unit is formed to serve as a cargo pump for oil tankers. It has the following advantages:
1) This cargo pump is also steam powered, so it has the same safety and reliability as steam direct acting reciprocating pumps.
2) Large displacement, generally up to 500~1500 tons/elbow. Not only is it suitable for medium-sized oil tankers, but also it is more suitable for the needs of large and ultra-large oil tankers. Moreover, this pump can also control the displacement by adjusting the opening of the drain valve.
3) It can operate continuously and smoothly. Under established operating conditions, this pump has uniform oil suction, stable pressure, low vibration, low noise, and will not operate under overload.
4) Light weight, small size, improved economy
However, the turbine centrifugal pump also has its disadvantages, such as: it has no dry suction capacity, and has a high sensitivity to inhale air. As long as air is inhaled, it can hardly inhale oil at all. Therefore, this type of pump is generally located at the bottom of the cabin, and when the oil is discharged to a certain extent, it will be stopped from use, and the cabin cleaning pump will be started to continue to discharge the oil. In order to overcome this disadvantage, a self priming device is also installed on the centrifugal pump. Another disadvantage of this type of cargo oil pump is that when sucking cargo oil with excessive viscosity, the friction between the impeller and the mucus increases, and the efficiency decreases. To maintain better efficiency, its displacement and pressure head must be reduced.
3. Electric centrifugal cargo pump
Using electric motors to drive centrifugal pumps as cargo pumps for oil tankers not only has the last three advantages of steam turbine centrifugal pumps, but also has the advantages of high efficiency, convenient manipulation and control, and is conducive to tanker automation. At the same time, it not only has the disadvantages of steam turbine centrifugal pumps, but also has its limitations, which are: due to the increasingly large-scale oil tankers, the displacement of cargo oil pumps is required to increase, and high-power electric motors are required to drive large displacement centrifugal pumps to meet the requirements of loading and unloading cargo oil on large oil tankers. However, the power of the power station on board cannot meet the needs of such a high-power motor, and the motor may generate sparks during operation, which is very detrimental to the fire and explosion protection of oil tankers.