During the operation of an evaporating plant,scale will form on the heating surface.The rate of scale formation will depend upon the operating temperature,the flow rate and the density of the brine.Scale formation will result in greater requirements for heating to produce the rated quantities of distilled water or a fall off in production for a fixed heating supply.Cold shocking,the alternate rapid heating and cooling of the  tube surfaces,for a boiling process type,can reduce scale to building up.Ultimately,however,the plant must be shut down and the scale removed either by chemical treatment or manual cleaning.

The rate of scale formation is decided by_____.

There are generally 3generators to form the main electrical source on board.Besides,there are some emergency electrical sources in reserve in case the main  generators fail to work.Battery is one of the main emergency electrical supply sources on board.It is used not only for stand-by purpose,but also for the routine charge and discharge work.The battery has specific function.It is able to supply electricity immediately.This gives it an advantage over any other stand-by electrical supply sources.So battery is now the essential equipment on almost all kinds of seagoing ships.In order to use the battery successfully,we must select the right type and size of  it,inspect and maintain it regularly.The capacity of the battery for marine use is normally given in ampere-hour,at 10-hour rate.For example,a250 ampere-hour battery can give25 amperes for 10 hours.

Battery is used for_____.

As we all know,a great number of machines and equipment on modern ships,either meant for the navigation of the ship and the handling of the cargo or used to serve the daily life of the people on board,run on electricity.So there must be some equipment functioning as the source of the electrical energy.From this power source to electrical apparatus,i.e.the above mentioned machines and equipment consuming electrical energy,there is a distance. Something is to be used to transfer electricity between them.For this purpose,cable and wire are used.

1.For how many purposes are machines and equipment on modem ships used?

Auxiliary machinery refers to all equipment in the engine room other than the main engine.It includes the generators,the boilers,the fresh water generators,the pumps and the valves.Some dek machinery,such as the  steering gear,the windlasses,the winches and cranes,also belongs to this group.These equipments are not so big as the main engine,but are much more in number.They are also indispensable.Without any kind of them,the ship  will be considered unseaworthiness.

Which of the following devices belong to auxiliary machinery?

An oil separator mainly consists of a separator bowl and can be adapted to both of these separating methods with only a little adjustment of the bowl.The bowl is made up of a stack of conical discs,which may number more than a hundred and are separated from one another by a small gap,where the separation of water and solid impurities just takes place.In the purifier bowl,the mixture is conducted in through the holes that correspond to the distributor holes in the bowl disc.

What does an oil separator consist of?

The windlass is the usual anchor handling device on the forecastle deck where one machine may be used to handle both anchors.A more recent development,particularly on larger vessels,is the split windlass where one machine is used for each anchor.Anchor capstans are used in some installations where the cable lifter rotates about a vertical axis.Only the cable lifter unit is located on deck,the driving machinery being on the deck below.

Where is the windlass?