Ship repair from A to Z: engine cooling system. Cooling system Schematic diagram of marine diesel engine cooling

Cooling of the main engine is carried out using fresh water in closed circuits. The cooling system of each engine is autonomous and is served by pumps mounted on the engines, as well as separately installed fresh water coolers and an expansion tank common to both engines.

The cooling system is equipped with thermostats that automatically maintain the set fresh water temperature by bypassing it in addition to water coolers. There is also the possibility of manually adjusting the water temperature.

Each fresh water circuit includes an oil cooler, into which water enters after the water cooler and thermostat. Filling of the expansion tank is provided from the water supply system using an open method.

The auxiliary engine is cooled using fresh water in a closed circuit. The auxiliary engine cooling system is autonomous and is serviced by a pump, water cooler and thermostat mounted on the engine.

The expansion tank with a capacity of 100 l is equipped with an indicator column, a low level indicator, and a neck.

Sea water cooling system

To receive sea water, two sea chests are provided, connected through a filter and clinker valves by a king stone line.

The cooling systems of the main and auxiliary engines are autonomous and are served by mounted seawater pumps. Mounted pumps on the main engines receive water from the seawall and pump it through the water coolers and overboard through non-return shut-off valves located below the waterline.

The auxiliary engine pump receives water from the kingston line, pumps it through the water cooler and through the non-return shut-off valve overboard below the waterline. There is also provision for water supply to the inlet pipe of the auxiliary engine pump from the pressure pipe of the sea water pump of the starboard main engine. A bypass pipe is provided to allow the auxiliary engine cooling water temperature to be controlled.

Water is drawn from the pressure pipelines of the sea water pumps of each main engine for cooling the thrust and stern tube bearings of the corresponding side.

Water is taken from the main engines' tidal lines for recirculation into the corresponding sea chests.

The compressed air compressor is cooled with sea water from a special electric pump with water draining below the waterline overboard.

A centrifugal horizontal single-stage electric pump ESP18/1 with a supply of 1 m3 at a pressure of 10 m of water column is installed as a cooling pump for the electric compressor.

Compressed air system

The MKO is equipped with 2 compressed air cylinders with a capacity of 60 kgf/s m2.

Air from one cylinder is used to start the main engines, for the operation of the typhon and for household needs, the other cylinder is a reserve and the air from it is used only to start the main engine. The total supply of compressed air on the ship provides at least 6 starts of one main engine prepared for start-up without pumping air into the cylinders. To reduce the compressed air pressure, appropriate pressure reducing valves are installed.

Filling the cylinders with compressed air is provided from one automated electric compressor.

Compressed air cylinders with a capacity of 40 liters are equipped with heads with the necessary fittings, a pressure gauge and a blowing device.

These heat exchangers are designed to cool heated liquids and gases ( drinking water, lubricating oil, outside air, etc.). Particularly important for the normal operation of a ship's power plant are oil coolers designed to cool oil heated during the lubrication of the main engine, auxiliary mechanisms and individual shafting components.

In Fig. Figure 32 shows the design of a tubular oil cooler, most common on marine vessels. The oil cooler consists of a steel cylindrical body 5, upper and lower covers 1, two tube plates 2, diaphragms 10, cooling tubes 4 and tie rods 12. Flanges are welded to the body at both ends, to which the covers are attached using studs. The tube sheets are flared brass tubes 4, through which cooling sea water flows. For the opportunity thermal expansion tubes, the lower “tube plate” is made movable; together with the bottom 1, it can move in the gland 13. The oil to be cooled enters the oil cooler body through the upper pipe 6 and washes the tubes from the outside. To better wash the tubes with oil, diaphragms 10 are installed inside the housing, which force the oil flow to change direction several times. The cooled, less viscous oil for lubricating the bearings of the shaft line and turbines is discharged through the middle pipe 11, and the more viscous oil for lubricating the gearbox is discharged through the lower pipe 3.

Rice. 32. Oil cooler.

There is a partition in the cavity of the top cover, so the cooling water, having entered the receiving pipe 8 of the top cover, goes down through pipe 9, and then rises up through the cooling pipes and is discharged overboard through pipe 7 of the top cover.

To control oil pressure and temperature, the oil cooler is equipped with instruments and fittings.

Modern ships are equipped with air conditioning units, which include air coolers. The operating principle of an air cooler is similar to an oil cooler. In a welded steel body, usually rectangular section, insert tube sheets with tubes rolled into them, which have ribs on the outer surface to increase the cooling surface. Covers are attached to the body on both sides. Cooling water or other liquid (for example, brine) flows through the tubes, and air enters the body of the cooler and, after cooling, is directed into the room to be cooled. In the cold season, an air cooler can work as an air heater if hot rather than cold water is passed through the tubes.

In addition to those mentioned, there are coolers of other designs: oil coolers with telescopic tubes, water coolers and air coolers with tubes made in the form of coils.

Sea water system

The sea water pipeline provides:

water intake by electric cooling pumps and desalination plant from the bulkhead, where sea water is supplied from the bottom or side sea chests through filters;

pumping fresh water into refrigerators and automatically draining water overboard or into circulation;

water supply to the desalination plant.

Basic technical data

Main engine sea water cooling system

To receive sea water into the cooling system, the MKO is equipped with bottom and side sea chests, from which water flows through filters into the sea water receiving box. The system is served by two RVD-450E cooling pumps, one of which is a backup. The backup pump turns on automatically when the water pressure in the system drops. The pump receives seawater from the seawater receiving box and supplies it through the temperature controller to the fresh water coolers.

This regulator, depending on the temperature of the sea water at the outlet of the pumps, directs water from the refrigerators overboard through a non-return shut-off valve and to the cooling pumps through a gate valve and a non-return shut-off valve into the sea chest or into the receiving line of the cooling pumps.

An emergency drainage line for the MO is connected to one of the main cooling pumps through a valve.

The air pipes from the sea chests are combined and led out to the open part of the VP and ends in single file.

To release air from the refrigerators, there are pipes that are connected to the air pipe from the sea chests.

Figure 20. Schematic diagram cooling with seawater SEU

Fresh water system

The fresh water cooling system includes:

fresh water cooling system for the main engine;

fresh water cooling system for diesel generators.

The fresh water cooling system is designed for:

cooling of the main engine and diesel generators;

warming up the idle main engine with a fresh water heater;

supplying heating water to water desalination plants;

General description and basic technical data

fresh water main engine cooling systems

The system is filled with water by an electric pump pumping fresh water from the boiler water reserve tank through the valves and into the expansion tank. Water is also supplied to the additive tank through a valve, and from it through a valve and tap into the expansion tank.

From the expansion tank through the valve, the system is filled with water, as well as leaks are replenished during system operation.

The main engine cooling system is served by two fresh water cooling electric pumps, one of which is a backup. The backup pump turns on automatically when the water pressure in the system drops.

Water is supplied to the main engine through a temperature controller for the water supplied by the pump, which regulates the amount of water passing through the refrigerators, providing the necessary temperature regime engine cooling.

Fresh water from the main engine enters the deaeration tank, in which the air and steam-air mixture are separated. On the fresh water main after the cooling pumps of the main engine, heating water is taken for desalination plants.

To heat the idle main engine, the system includes a fresh water heater, to which steam is supplied from the heating system.

Fresh water cooling system for diesel generators.

The system is filled with water by an electric pump pumping fresh water from the boiler water supply tank through the valves.

Water is supplied to the expansion tank of diesel generators, from there, through valves, the system is filled, as well as leaks are replenished during system operation.

The fresh water system of each diesel generator is serviced by its own centrifugal pump, hung on the engine.

Water is supplied to the jackets of diesel generators through fresh water refrigerators and valves.

To maintain a constant fresh water temperature, a thermostatic valve is installed at the cooling water outlet of the engines.

To put an idle diesel generator into a “hot” reserve, an electric heater is provided in the engine’s fresh water system.

Figure 21. Schematic diagram of SPP cooling with fresh water

In the event of damage to the fresh water cooling system, diesel generators can be cooled with sea water by removing the blind flanges separating the fresh and sea water systems.

The steam-air mixture is discharged from diesel generators into the expansion tank of diesel generators.

The system's pipelines are painted to match the color of the room. Fresh water pipelines are marked with two wide green rings.

Instrumentation.

To monitor the operation of the system, pressure gauges, local and remote thermometers, low level alarms, pressure and temperature alarms are provided.

Compressed air system

The medium and low pressure compressed air system provides:

Filling the starting air cylinders of the main engine and diesel generator with compressed air from electric compressors, low pressure filling the cylinders of CO apparatus;

supply of compressed air from cylinders to engine starting devices during startup;

blowing main engine oil filters;

ship needs, pneumatic tools and pneumatic tanks.

The high pressure compressed air system provides:

Filling from the electric compressor of cylinders from the starting cylinders of the emergency diesel generator and diesel motor pump of the pneumatic supply cylinders of the system and cylinders of lifeboats.

Air supply and gas exhaust systems

All cargo and slop tanks are equipped with a gas exhaust system, autonomous for each tank and designed to ensure gas exchange between the cargo tank and the atmosphere.

Each cargo and settling tank is equipped with a high-speed gas release device and a vacuum valve with a flame-interrupting mesh. Gas is released from the tanks through a high-speed gas outlet device at a speed of at least 30 m/s.

Figure 22. Schematic diagram of the SEU compressed air system

The cross-sectional area of ​​the pipes of the autonomous gas exhaust system ensures the removal of gases from one tank during cargo operations with a capacity of no more than 1100 m3/h.

Gas exhaust system of the main and auxiliary engines

The gas exhaust system ensures exhaust gases are removed from the main engine through the recovery boiler, auxiliary diesel generators, emergency diesel generator and diesel motor pump through mufflers into the atmosphere. The recovery boiler and all silencers are equipped with spark arresters.

Figure 23. Schematic diagram of the SEU gas exhaust system

The exhaust pipes are insulated and covered with a metal casing.

The gas exhaust system provides for constant drainage of tar and emergency drainage of water from the recovery boiler.

Refrigeration system with one chiller outdoor installation with axial fans - one of the most common and fairly simple systems. As a rule, water is used as a coolant in the system; in some cases, it is possible to use coolants with low freezing temperatures (ethylene glycol solution, brines, etc.).

The coolant circulates in the system using a pump group. In the diagram shown as an example, the pump group consists of two pumps, one of which is the main one, the second is a backup one.

Expansion membrane tank serves both to prevent hydraulic shocks during pump operation and to compensate for changes in the volume of coolant due to changes in its temperature.

The accumulator tank is designed to increase the thermal inertia of the system and reduce the number of start/stop cycles of the refrigeration machine.

When using consumers with variable coolant flow (for example, fan coil units with cooling capacity control by changing the flow rate with two-way valves), it is necessary to ensure a constant flow of liquid through the evaporator heat exchanger of the refrigeration machine. The diagram shows an option with installing a differential pressure regulator on the jumper between the distribution manifolds to ensure constant flow on the evaporator. In the case of using consumers with constant flow ( three way valves with bypass on consumer heat exchangers), a jumper with a differential regulator is not required.

Disadvantages of the considered refrigeration system scheme:

• lack of reservation refrigeration equipment,

In some cases (with significant refrigeration capacity of the system, the need for partial redundancy of refrigeration equipment), it becomes necessary to install several refrigeration machines operating on one refrigeration system. As an example, a diagram is shown with the installation of two chillers with air-cooled condensers.

The operating principle of the system is similar to that of a single chiller system.

The disadvantages of the considered refrigeration system scheme are:

• the need for partial seasonal drainage/refilling of the coolant (in the case of using water) and, as a result, increased corrosion of pipelines and fittings.
• fluctuations in coolant temperature when one of the refrigeration machines is turned on/off.
• impossibility of year-round operation of the system.

A chiller is a water-cooling machine designed to reduce the temperature of water or liquid coolants. This page will discuss in detail chiller circuit and device , as well as how it works.

Based on an almost non-stop cycle (depending on the type of consumer). is to cool the water heated by the consumer by several degrees and supply it in this form to the consumer or to an intermediate heat exchanger, in which the water (if its temperature does not allow it to be sent directly into the water) is cooled by almost any number of degrees. The required value for reducing the temperature of the coolant is set by the future user of the water cooler, depending on the type and characteristics of the coolant required by the consumer of this same coolant. Equipment that requires cold energy transferred from the water-cooling machine to the coolant can be a wide variety of consumers: machine tools, air conditioning systems, injection molding machines, induction machines, oil pumps, manufacturing machines polyethylene film and other systems that require a constant supply of chilled water during their operation. Various modifications and a wide range of cooling capacities allow the use of water coolers both for one consumer with very little heat generation, and for enterprises with a large number machines with high thermal power output. In addition, water coolers are used in the food industry in many technological lines for the production of drinks and other products, to ensure cooling of ice at skating rinks and ice rinks, in metalworking ( induction furnaces), in research laboratories (ensuring the operation of test chambers), etc. etc.

Choosing a water-cooling machine is a serious task that requires such specific knowledge as the design of the chiller, as well as the principle of interaction of the chiller together with other elements general scheme. To make an intelligent decision about which cooler will optimally fit into the scheme of joint work of all consumers and the cooler itself, you need extensive experience in calculations, selection and subsequent successful implementation of a set of equipment based on water coolers in process, which our specialists possess. A separate area is chiller automation, which allows you to make the operation of the device even more efficient, optimizing the control and management of all ongoing processes. Of course, in order to select a refrigeration unit, there is no need to know all the intricacies of the operation of the refrigeration machine and the automation of the chiller, but fundamental knowledge of the principles will help you most clearly formulate terms of reference for calculation and professional selection of all elements, from which a chiller circuit will be assembled jointly with consumers.

Chiller circuit

In the drawing below, it will be disassembled and a description of its elements and their functionality will be given. As a result, you will understand how the chiller and all its elements work.

A water cooling machine works on the principle of gas compression with the release of heat and its subsequent expansion with heat absorption, i.e. release of cold. Water cooling machine consists of four main elements: compressor, condenser, expansion valve and evaporator. The element in which the cold is produced is called the evaporator. The task of the evaporator is to remove heat from the cooled medium. To do this, coolant (water) and refrigerant (gas, also known as freon) flow through it. Before entering the evaporator, the liquefied gas is under high pressure, entering the evaporator (where low pressure is maintained), freon begins to boil and evaporate (hence the name Evaporator). Freon boils and takes energy from the coolant, which is located in the Evaporator, but is separated from the freon by a sealed partition. As a result of this, the coolant is cooled, and the refrigerant increases its temperature and passes into a gaseous state. The refrigerant gas then enters the compressor. The compressor compresses gaseous refrigerant which, when compressed, heats up to high temperature at 80...90 ºС. In this state (hot and under high pressure) freon enters the condenser, where it is cooled by blowing with ambient air. During the cooling process, the gas - freon - condenses (therefore, the block in which this process occurs is called a condenser), and during condensation the gas turns into a liquid state. At this point, the chain of converting freon from liquid to gas and back comes to its beginning. The beginning and end of this process are separated by a TRV (thermal expansion valve), which is essentially a large resistance as freon moves from the condenser to the evaporator. This resistance provides a pressure drop (before the expansion valve - a condenser with high pressure, after the expansion valve - an evaporator with low pressure). Along the path of freon movement along a closed circuit, there are also secondary elements that improve the process and increase the efficiency of the described cycle (filter, valves and solenoid valves and regulators, subcooler, oil adding system for the compressor and oil separator, receiver, etc.).

Chiller device

The diagram below shows an image of a compact water cooling machine - a chiller device, monoblock design in a partially disassembled form (the protective sides of the housing have been removed). This image clearly shows all the elements indicated in the diagram of this water-cooling machine, as well as elements of the water circuit that are not included in the schematic diagram (water pump, flow switch on the coolant supply pipeline to the consumer, water filter, pressure gauge for measuring coolant pressure, storage tank for water, filter on the water line).

Peter Kholod is a supplier of Industrial water coolers and machines for air conditioning systems. We are ready to develop and create chillers for you that are suitable for your professional tasks. We also produce service, repair and automation of chillers. Whether you want to remotely control your own equipment, or would like to protect it from common problems, chiller automation will allow you to achieve all these goals. Our team is ready to implement projects of any size and complexity. Just contact us in a way convenient for you, and we will advise you on any issue of interest.