Marine diesel engines and their repair. Fuel system of marine diesel engine
Marine diesel engines are the sourceenergy that moves the ship. The rotation of the crankshaft is transmitted to the transmission, consisting of a reducer, a complex shaft mechanism and a propeller propeller, which gives the turn to the vessel. The larger the motor ship, the more developed should be its energy system, which should ensure the safety of the vessel in the voyage. If the main engine fails, the backup engine switches on, because stopping a huge container ship or a multi-deck dry cargo ship in the middle of the ocean in storm conditions is tantamount to its death.
Marine diesel engines appeared in the beginningAnd immediately declared themselves as reliable, efficient and, most importantly, compact units. The first ship with a diesel engine was the Danish "Zeeland", launched in 1912. Two engines of 200 liters were installed on the ship. with., Each of which set in motion its propeller. The appearance of a vessel with an unusual motor made a furor and was the beginning of a new era of power diesel installations.
Development of power diesel installations in the fleetbegan at a rapid pace after the Second World War. The prospect of further use of unpretentious propulsors was obvious, and many machine-building firms around the world engaged in their production. As is usually the case, with the development of large-scale industrial production of any product that is in high demand, competition has begun. As a result, there were unique projects, during the implementation of which, powerful, super-reliable ship engines were created.
Power diesel engine on a largeThe ship consists of one main engine and several auxiliary ones that work on the life support of the ship. These are generators, pumps, ventilation, compressors and many other mechanisms.
On especially large ocean liners there may beinstalled several main engines and many auxiliary ones. All motors are diesel. They are serviced by a team of mechanics, repair fitters and test engineers.
Marine diesel engines are divided intofour-stroke and two-stroke. The difference between the two species is significant. The four-stroke principle of operation consists in the passage of the operating cycle for two turns of the crankshaft or four strokes of the piston. Active action occurs only during one measure, the remaining three - preparatory.
Single-cycle two-stroke engineis carried out in one turn. The principle of compression of the combustible mixture and subsequent ignition here is different. In the cylinder there are so-called scavenging windows, by means of which there is a forced purging of the combustion chamber and, thus, there is no need to exhaust the exhaust gases through the valves. The number of cycles is reduced exactly by half.
There is also a frequency classificationrotation. Low-turn motors - up to 150 rpm and medium-speed motors - up to 600 rpm. High-speed engines for large and very large vessels do not exist due to the specificity of their operation, high load and long-term operating time.
Marine diesel engines for small ships
Small boats, boats and river class shipsare equipped, as a rule, with one motor. The power of such a diesel engine can be different, depending on the purpose for which the vessel is intended. High-speed boats have pick-up engines, and for walking, sightseeing and cruise, low-speed motors are installed. Ships of the patrol coastal service usually have two sufficiently powerful diesel engines, one of which is constantly engaged, and the second is activated as needed.
Marine diesel engines for small boatsare designed for stationary installation. They are usually compact and economical, with a high service life. Outboard motors are usually gasoline, because they have the ability to quickly launch.
Diesel fuel for marine engines
For stable operation of the power plant on the ship, it is necessary to use high-quality fuel (diesel fuel). Its suitability is determined by the following criteria:
- octane number;
- resistance to detonation;
- cetane number;
- composition fractional;
- completeness of combustion, degree of smoke, toxicity;
- viscosity and density, as a factor of normal supply to the system;
- properties of low-temperature, determining the functioning;
- level of purity;
- flash point, from the point of view of safety of application;
- presence of sulfur compounds, metals and unsaturated hydrocarbons, as stimulants of carbon formation.
- international - FO, HFO, MGO, MDO, IFO 380, IFO 380LS;
- Russian analogue - L-62, SMT1, CMT2, F-5, DM, IFO 380;
- The Russian standard for fractions is low-viscous, medium-viscous, high-viscosity, light, heavy.
The main standards adopted in Russia, regulating the quality of diesel fuel for marine engines:
- Summer "L" - used at temperatures above zero degrees Celsius;
- winter "Z" - is used at temperatures up to minus 20 degrees;
- Arctic "A" - the temperature to minus 50 degrees Celsius.
- low-viscosity marine fuel - produced according to TU 38.10;
- DM brand - the highest category for ship small-turn engines;
- fuel oil fleet F-5 - produced in accordance with GOST 10-5-85; fuel oil fleet F-30, F-180, F-380 - are manufactured according to TU 0252-003-2905.
Fuel system of marine diesel engine
Fuel supply to the power ship installation is carried out by means of the fuel system to the main and auxiliary engines. Simultaneously with the main function, the system should provide:
- loading of fuel into tanks at the base and its storage;
- cleaning of fuel from foreign matter and water;
- if necessary, cooling of the injectors;
- fuel separation.
Receiving fuel from shore devicesIt is carried out by means of a deck pipeline, which has choke connections on both sides. On passenger ships the fuel intake takes place in separate isolated rooms. The received fuel is stored in the tanks below deck and onboard tanks communicating with each other. All tanks are equipped with pumps for pumping, which duplicate each other, in case of failure of one of them. Before the vessel leaves for the flight on board, the fuel is separated and purified, after which the fuel is pumped into the consumable tanks.
Marine engine brands
Energy diesel installations are produced insuch quantity that it is not possible to trace their nomenclature. Famous engine manufacturers for large marine and oceanic vessels are:
- Scan Diesel (Croatia).
- Mitsubishi (Japan).
- Hyundai (South Korea).
- Lombardini Marine (Italy).
- Wartsila (Finland).
A separate category includes marine dieselengines "YaMZ", produced by the Yaroslavl Motor Plant. Diesel engines "YAMZ" for marine vessels of medium displacement are the most available to Russian shipbuilding enterprises both at price and quality.
Repair of power ship installations
Each engine operating under conditionsconstant loads, there is a gradual natural development of friction surfaces of mechanisms. Sooner or later, there is a need for ongoing or major repairs. Shipowners try to carry out repairs on site, on their own. However, this is not always possible, because often replacement of worn parts requires special equipment, as well as qualified specialists. In this case, the engine is dismantled and sent to the manufacturer.
Repair of marine diesel engines takesa few months, motor ships in this case are idle. However, the shipowner may have a backup engine, which is installed instead of removed. So you can avoid forced downtime, which is very costly.
Among the ship's engines there are record-holders. The largest marine diesel engine is the Wartsila-Sulzer-RTA96-C model. Produced in a Finnish company. The model is designed taking into account multivariance, the line includes several types. To order a super-engine it is possible in a format of 6 or 14 cylinders. The choice is made by the customer six months before the start of work.
The cylinder diameter of this giant is 960 mm. Engine power - 109 thousand liters. from. Ocean container ship with such a motor easily develops a speed of 46 kilometers per hour.