Sewage treatment

To meet certain standards, introduced by International legislation all new ships have sewage treatment plants installed. There are two particular types of sewage treatment plant using either chemical or biological methods.

Figure 4.6 Biological sewage treatment plant,

Incinerator

To achieve the ultimate situation of no discharge a suitable incinerator is used in conjunction with a sewage plant and with facilities for burning oil sludges thus forming a complete waste disposal package.

Two Stage Oily Water Separator

DECK MACHINERY AND EQUIPMENT. MAINTENANCE.

Words and expressions

mooring winch - швартовая лебедка

windlass - брашпиль

cargo handling equipment - оборудование для обработки грузов

anchor handling equipment - якорное устройство

hatch cover - люковое закрытие, крышка люка

item - зд: наименование

life-boat - спасательная шлюпка

life-raft - спасательный плот

emergency equipment - аварийное оборудование

watertight door - водонепроницаемая дверь

bow thruster - носовое подруливающее устройство

currently - в настоящее время

winch barrel (drum) - барабан лебедки

warp end - турачка

geared drive - зубчатая передача

self-tensioning unit - уст-во, автоматически поддерживающее заданное усилие

recent development - зд: современный вариант (версия)

split windlass - брашпиль с разделенным приводом

cable lifter - звездочка (брашпиля)

clutch gear handle - ручка привода сцепления

band brake - ленточный тормоз

clutch lever - рычаг сообщения

brake handle - рукоятка тормоза

derrick - грузовая стрела

derrick rig - стреловое устройство

union purchase - спаренные грузовые стрелы, работающие на один гак ("телефон")

quayside - причальная линия

to enable - давать возможность

Samson post - грузовая колонка (полуматка)

stay -оттяжка

topping wire - топенанта

hook - гак

outboard derrick - стрела, вынесенная за борт

to rotate - вращаться

hoisting and luffing motors - механизм подъема груза и изменения вылета стрелы

turntable base - поворотная площадка

operator's cab - кабина крановщика

slewing motor - поворот крана

to expose - подвергаться

enclosure - оболочка, зд: поверхность

splash lubrication - смазывание разбрызгиванием

gearing - зубчатая передача

to grease - смазывать

pressure grease point - пресмасленка

open gear compound - смазка для открытых приводов

to be associated with - быть связанным с, зд: зависеть от

TEXT

Deck machinery includes mooring equipment, anchor handling equipment, сагgо handling equipment and hatch covers. Other items include life-boats and life-rafts, emergency equipment, watertight doors and bow thrusters.

Three forms of power are currently in use for driving deck machinery: steam, hydraulic and electric. Winches with various arrangements of barrels are the usual mooring equipment used on board ships. (Figure 5.1 Mooring winch, p. )

Modern mooring winches are arranged as automatic self-tensioning units.

The windlass is the usual anchor handling device 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. (Figure 5.2. Windlass, p. )

Cargo winches are used with the various derrick systems arranged for cargo handling One of the several possible derrick arrangements or rigs is a derrick rig, known as "union purchase" One derrick is positioned over the quayside and the other almost vertically over the hold. A combination of movements from the two winches enables lifting, transfer and lowering of the cargo. (Figure 5.3. Union purchase rig, p. )

Cranes have replaced derricks on many modern ships. Positioned between the holds often on a platform which can be rotated through 360º the deck crane requires only one man to operate it. (Figure 5.4 General cargo crane, p. )

All deck machinery is exposed to heavy weather. Total enclosure of all working parts is usual with splash lubrication for gearing. The various bearings on the shafts must be greased by pressure grease points. Open gears and clutches are lubricated with open gear compound Particular maintenance tasks are associated with the type of motor drive used.

Figure 5.1 Mooring winch.

Figure 5.2. Windlass

Figure 5.3. Union purchase rig.

Figure 5.4 General cargo crane

Unit Two. Different liquids in marine use. Fuel oil, lube oil and water treatment.

Any future motorman should know that there are several liquids that are essential for efficient engine room operation. He studies their main properties and the basic ways of treatment for gaining higher efficiency and, of course, finds out about some liquids that are produced by a ship and her crew that should be also treated before the discharging. Let’s enumerate them in brief.

Ship’s marine diesel engines run on heavy fuel oil (HFO) nowadays with low sulfur content, or on marine diesel oil (MDO). The lube oil is widely used for lubricating different machinery. For efficient operation of the engine room it is necessary to have sufficient volume of fresh water that can be achieved by seawater treatment. Every ship produces bilge water and sludge that should be treated in accordance of their type.

Part One. HFO and MDO. Treatment of Fuel Oil

Both HFO and MDO have four main properties, such as density, viscosity, flash point and pour point. The latest one is of certain concern because fuel must be stored at a temperature above that of its pour temperature to avoid wax formation and for ease of transfer via pumps for treatment and intermediate storage in settling tanks and day tanks. HFO has some more properties that should be taken into account. They are ash and sulphur content, specific gravity and carbon residue. Heavy fuel combustion products remain high in NOx, SOx, and CO2 in the exhaust gases. It’s one of the main disadvantages and the reason for MDO usage. HFO contains a lot of contaminants that are removed from the lighter oils. This makes it much cheaper than other lighter marine fuels.

In daily operation, diesel or heavy fuel oils are contaminated with water and solids. To enable the propulsion engines to work with the minimum wear possible, these oils have to undergo continuous treatment.

Treatment of fuel oil

Answer the following questions: What is the difference between MDO and HFO? What is the reason of the usage MDO/HFO? What is flash point/pour point? Why should any fuel be treated? What do you know about fuel oil treatment? *** The words in italics and their meanings can be found in the vocabulary section on the 5th page.

Part Two. Lubricating Oil.

Lubrication is necessary to dissipate heat caused by friction, reduce friction and combat wear and tear between the surfaces of two moving components. The lube oil has the following properties: viscosity, volatility, alkalinity, detergent and oiliness. The viscosity must be calculated by taking into consideration the application and operating temperature range. Volatility should be taken into account to prevent crankcase explosions. Alkalinity is especially important for the cylinder lubrication, as it acts as a neutralizer to the acidic sulphur residues from combustion of HFO. Detergents are added to the lube oil to inhibit (замедлять) the formation of deposits of the moving components, also it helps to keep the oil clean.

To maintain the lubricating oil's operating parameters and properties, the temperature and pressure must be controlled. The solids and water should be removed from the oil through centrifuging. The use of low quality lubricating oil can lead to several problems:

1. Less amount of lube oil in circulation causes rise in temperature thus reducing the viscosity leading the failure of boundary lubrication due to decrease in oil film thickness.

2. Lubrication oil properties can be lost or the oil viscosity will increase.

3. Increase in friction, wear, heat corrosion, contamination and noise and it reduces the engine performance.

The purifying of the oil is also necessary to maintain the original properties of the oil. Knowing the quantity of engine oil, the rule states that the amount of system oil depends on the type of engine. It should be 1lit/bhp and lube oil should not circulate more the 15 times/hr.

In daily operation, the lube oils of diesel engines are continuously contaminated. All rotating or sliding parts deposit metal impurities. Added to this are residues of the combustion process, condensed water decomposition products which settle in the lube oil sump. The oils themselves can also contain acids which, in combination with catalyzing foreign substances, can result in premature ageing of the oil. At the same time, on diesel engines, residues of the combustion process and incombustible constituents from the cylinder can also reach the lube oil circuit. These residues can lead to considerable symptoms of wear at bearing points, pistons and cylinders.

Lube Oil Treatment

Answer the following questions: What is the main property of oil? Why? What can the quality of the oil be worsen? What are the problems caused by using the low quality of oil? How is lube oil contaminated? What do you know about lube oil treatment?

Exercise I. Put the verbs from the brackets in the correct form.

1. If the viscosity of the oil is too great, it ___ (to affect) the operation of the moving components against each other-offering greater resistance to motion.

2. If the viscosity is too low it ____ (to be able, to flow) too freely between the surfaces of the components, failing to lubricate them properly.

3. If the oil’s flash point ___ (to be) low, it ___ (to ignite) due to the high temperature of a hot spot causing an explosion of crankcase. The flash point of a marine diesel engine lube oil ____ (should, to be) above 200°C.

4. The proper treatment ____ (to achieve) aboard ship by maintaining the optimum temperatures and pressures of both the fuel and lube oil through the use of pumps, heaters, and coolers.

5. Cleanliness as well as the regular maintenance and inspection of the lube and fuel oil cleaning components __ (to be) very important and ___ (to carry out) by means of centrifuges and filters.

6. The supply of good quality low sulfur heavy fuel oil ___ (to be) essential to the marine diesel engine combustion process.

7. Due to its properties HFO __ (to require) to be kept at high temperature for storage and usage, it __( to achieve) by use of low steam coils in the bunkers and storage tanks and a series of heaters between here and the engine fuel pumps and injectors to keep the oil between 104°F in the main bunkers and 250°F at the main engine injectors.

Part Three. Treatment of Bilgewater and Sludge and Sea Water Desalination.

Bilgewater is created by leaks of salt water, cooling water, fuel oil and lube oil, by the dewatering of sedimentation and sludge tanks, by the draining off of various cleaning processes and also by particles of soot and dirt.

Every ship, whether it is a container ship, an oil tanker or a freighter, produces bilgewater which is disposal problem. The IMO specifies that bilgewater may be discharged into the sea only if its residual oil content is below 15 ppm. At the same time, the oil recycled from the separation process can be reused for a variety of purposes. Oil recycled out of the separation process can be reused as fuel oil, for example. Recovered lube oil can be used as a fuel to generate heat.

Treatment of Sludge Containing Oil and Water Sludge containing oil and water is created by a variety of factors, including sedimentation of solids in sedimentation tanks, tank dewatering processes, leaks or cleaning cycles in backflush filters and separators for treating fuel oil and lube oil.

There were two methods of the sludge disposal, such either to incinerate it on board or to dispose of it on shore. Incineration is an expensive process because the sludge has to be dewatered by evaporators and then mixed with precious diesel oil to generate a combustible fuel. Disposal on land is also associated with considerable costs, as the sludge has to be transported to a waste disposal site which in turn has to be paid for. The specially developed separator uses dewatering and oil recovery processes to reduce the volume of sludge. At the same time, valuable fuel oil is recovered, the bilgewater system is freed from oil residues.