Trombone reed

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View of the entry and exit trumpets for the cooling water supply of a piston
The piston cooling water is cooled back in the cooling water system (see in the lower part of the overall system)

A trombone tube is a telescopic tube for supplying and draining cooling water to marine diesel engines of the cross-head design.

Piston cooling of crosshead diesel engines for propulsion of ships

The cooling of large, slow-running (90 - 180 / min) two-stroke marine diesel engines is carried out with fresh cooling water, which is cooled back by seawater in heat exchangers . These engines are usually equipped with a crosshead (crosshead diesel engine). The piston rod only performs vertical movements and can be easily sealed with a stuffing box . The combustion chamber and the engine room are therefore separated from one another and sulphurous combustion residues do not get into the engine room. This is important because almost all large marine diesel engines run on heavy fuel oil, which can contain up to 4.5 percent sulfur.

The piston of the engine is subject to high thermal loads, so it is cooled with water or oil ( piston cooling ). A separate cooling system with its own pump is used to cool the pistons to ensure constant circulation. With water cooling, the water is supplied to the flask with the help of hoses or pipes that are flanged to the crosshead.

Trombone reeds

If pipes are used, two pipes run telescopically into one another in order to follow the vertical movements of the pistons. This connection between the reciprocating engine and the cooling water supply line is called a trumpet and the pipes are called trumpet pipes.

An air chamber with an air cushion is located in the inlet and outlet pipes above the water space in order to avoid water hammer and the resulting pipe ruptures. To maintain the air cushion, the air chambers were constantly supplied with compressed air from a small compressor attached to the main machine .

  • Entry and exit trumpets for the cooling water supply to all pistons of a two-stroke main engine with around 10,000 hp

  • Compressor attached to the diesel engine to supply the air chambers of the trombone tubes with compressed air

  • Motor principle without cross head (plunger piston motor) and with cross head (cross head motor)

  • Cross-section of a low-speed, modern marine diesel engine in a typical two-stroke design, the crosshead and the stuffing box above it (model) are clearly visible

literature

  • Bunnenberg, K.-D .: Marine Diesel Engines. (8th completely revised edition), 1967 VEB Verlag Technik Berlin