Hydraulic cylinder
2023-10-10Cylinder Crane Operation Of Marine Diesel Engine
With the use of small size, high power, high cooling circulating water temperature and high-quality sealant in modern ship mainframes, the working cycle of hanging cylinders and pulling cylinder liners is greatly extended.
This is very beneficial to improve the power and safety of ships, and is an inevitable trend to reduce operating costs and improve economic benefits.
But it also brings new issues and new requirements to maintenance managers.
Analysis of the Reasons for Difficulty Opening the Cylinder Head
As long-stroke DC scavenging type models are widely used at present, most models, especially MAN models, have the cylinder head inserted into the upper part of the cylinder liner, and the seal between the cylinder head and the circulating cooling water of the cylinder liner is made by special rubber To be done.
In order to increase the reliability of the seal, the clearance between the cylinder head and the sealing surface of the cylinder liner should be as small as possible.
As long as the safety regulations for the maximum expansion coefficient can be met.
Under normal circumstances, there is no difficulty in lifting the cylinder and pulling the cylinder liner.
However, due to some reasons (such as not testing according to the requirements, putting water treatment agent; sometimes encountering the backflow of seawater into the cooling system, such as the failure of the heat exchanger of the water generator, etc., the quality of the water will be poor. High water quality; poor water quality in some port areas, etc.), can make the cooling water in the system, especially in the small gap, large thermal conductivity, high water temperature, precipitation of solid sludge, scale and other substances.
It is especially serious in the sealing section between the cylinder head and the cylinder liner of the main engine, and the cylinder liner and the cylinder block.
Because the gaps in these places are small (some models are only tens of wires), the heat transfer there is faster and the relative temperature is higher, so there are more solids precipitated in the circulating water.
It is tightly wrapped with the sealing order. In addition, since the circulating water there is relatively static, it is the accumulation place of solid sediments.
Over time, the sediment will accumulate more and more, which will not only affect the heat dissipation, but also make the sediment harden, and also cause the premature aging of the rubber seal, which will gradually lose its elastic force, which will cause the cylinder head to be opened when the cylinder is lifted. , pulling the cylinder liner, etc. to increase the resistance, making it difficult to open the cylinder head, especially on some old ships and ships with poor management.
Under normal circumstances, there is no difficulty in lifting the cylinder and pulling the cylinder liner.
However, due to some reasons (such as not testing according to the requirements, putting water treatment agent; sometimes encountering the backflow of seawater into the cooling system, such as the failure of the heat exchanger of the water generator, etc., the quality of the water will be poor. High water quality; poor water quality in some port areas, etc.), can make the cooling water in the system, especially in the small gap, large thermal conductivity, high water temperature, precipitation of solid sludge, scale and other substances.
It is especially serious in the sealing section between the cylinder head and the cylinder liner of the main engine, and the cylinder liner and the cylinder block.
Because the gaps in these places are small (some models are only tens of wires), the heat transfer there is faster and the relative temperature is higher, so there are more solids precipitated in the circulating water.
It is tightly wrapped with the sealing order. In addition, since the circulating water there is relatively static, it is the accumulation place of solid sediments.
Over time, the sediment will accumulate more and more, which will not only affect the heat dissipation, but also make the sediment harden, and also cause the premature aging of the rubber seal, which will gradually lose its elastic force, which will cause the cylinder head to be opened when the cylinder is lifted. , pulling the cylinder liner, etc. to increase the resistance, making it difficult to open the cylinder head, especially on some old ships and ships with poor management.