Maintenance and operating troubles and remedy

Maintenance involves the usual checks and overhauls common to reciprocating machinery, e.g. crankcase oil level, cooling water system, operating temperatures and pressures, etc. The suction and delivery valves are most troublesome. These valves are automatic requiring a small pressure differential to operate.

 The constant rapid opening and closing action of the valves may require seats to be refaced. Overheating, use o f incorrect lube oil or the presence of dirt may result in sticking or pitting of the surfaces. The suction and delivery valves should be stripped and all parts carefully cleaned and examined and worn parts replaced and the valve seat and plate lightly lapped before reassembly to ensure a good seal.

HEAT EXCHANGERS

WORDS AND EXPRESSIONS

to require                                   conducting surface                      opposite                                     counter or contra flow                  fairly heat transfer                                shell and tube cooler                    plate type heat exchanger              tube bundle                                 corrosion resistor                         visible joint                             radial flow circular baffles             safety expansion ring    double joint                                 removable cover                           shell frame plate                                   carrier bar                                support post                                tie bolt                                        plate pack                                    guide bar

требовать проводящая поверхность противоположный противопоток  довольно теплопередача трубчатый охладитель пластинчатый охладитель пучок труб антикоррозийный протектор наружное соединение направляющие пластины потока предохранительное расширительное кольцо рамовая плита балка корпус, кожух поддерживающая опора стяжной болт зд: двойное уплотнение съемная крышка пакет пластин направляющая балка

TEXT

Heat exchangers on board a ship are mainly coolers where a hot liquid is cooled by sea water. There are some instances where liquid heating is required, such as heavy fuel oil heaters and sea water heaters for tank cleaning.

In the heat exchange process the two liquids pass on either side of a conducting surface. The heat from the hot liquid passes to the cold liquid and the conducting surface is at a temperature between the two. Marine heat exchangers usually have the two liquids flowing in o pposite directions, i.e. counter or contra flow which provides a fairly constant temperature difference between the two liquids and therefore the maximum heat transfer.

Coolers at sea fall into 2 groups: the shell and tube and the plate type. Heaters are similar in construction to coolers.

In the shell and tube design a tube bundle is fitted into a shell.

Figure 4.2. Shell and tube cooler,

   

The plate type heat exchanger is made up of a number of pressed plates surrounded by seals and held together in a frame.

Figure 4.3 Plate-type heat exchanger: (a) construction.

 

HEAT EXCHANGERS.  PLATE TYPE.  OPERATION,

MAINTENANCE AND TROUBLESHOOTING.

WORDS AND EXPRESSIONS.

troubleshooting                     - выявление повреждений

to reduce                              - уменьшать, снижать

considerably                          - значительно

filling                                     - заполнение

occasionally                           - изредка, время от времени

afterwards                            - впоследствии

circumstance                         - обстоятельство

О- ring                                - уплотнительное кольцо

connection                            - связь, соединение

gasket                                   - прокладка

sealing surface                        - уплотняющая поверхность

deposits                                 - отложения

flow rate                                - расход

visible                                   - видимый

further                                   - далее, затем, зд: сильнее

deformed                               - деформированный

double                                   - двойной

adjoining plate                        - прилегающая (примыкающая) пластина

volume                                  - объем, размер

to decrease                             - уменьшать

respective                              - соответствующий

hole                                       - отверстие

to apply                                 - применять

opposite side                          - противоположная сторона

TEXT

Temperature of coolers is controlled by adjusting the cooling liquid outlet valve. The inlet valve is left open which ensures a constant pressure within the cooler. This is very important with sea water cooling where reducing pressure can result in air remaining in a cooler which will considerably reduce the cooling effect. Vents provided in the highest point of coolers should be opened on first filling and occasionally afterwards. Drain plugs are also fitted at the lowest point in coolers.

The plate heat exchangers should be opened and cleaned regularly and under normal circumstances every six months. The Q-rings in the connections, the gaskets and the sealing surfaces on the back of the plate should be checked before the heat exchanger is re­assembled.