The fuel and lubricating oil used in the Marine diesel engine must be purified before being used in the machine, and the water and miscellaneous substances are removed.
The quality of purification has great effect on the reliability and service life of diesel engine.
Oil separator is a key equipment for purifying oil and lubricating oil.
 

1. Basic working principles and types of oil separator.

In the oil mixed with water and impurities, the density of mechanical impurities is the largest, the density of oil is the least, and the density of water is somewhere in between.
Oil in the sedimentation tank for a certain amount of time can make mechanical impurities and water precipitation separation, but the speed is extremely slow.
At present, the ship mainly relies on centrifugal oil purifier to purify fuel and oil.
Its working principle is: let the need to purify the oil into the oil purifier for high-speed rotation, the density of the larger droplets and mechanical impurities by centrifugal force, the largest is flung to the peripheral, water is derivation, impurity removal (discharge) on a regular basis;
The less dense oil is absorbed by the centrifugal force, which flows in and out of the outlet near the shaft, and the oil is purified.
Since the centrifugal inertia force of impurities and water is several thousand times larger than its own gravity, the centrifugal separation machine has the advantages of short cleaning time, high flow rate and good effect.
     

The oil separator can be divided into purifier and clarifier according to different purposes.
The water and impurities in the oil are separated when the water content in the oil is high.
When the water contained in the oil is relatively small, use a separate machine to separate the impurities and a small amount of water from the discharge outlet.
The core part of the oil separator is the separator.
The separating cylinder body 2 is driven by the vertical shaft (the normal rotating speed is 6000-8000r/min), and there are several stainless steel separator plates in the separator. The disk thickness is about 0.4-1.5mm, and the disk spacing is about 0.5-1.0mm, and the set is on the plate rack 10.
The plate frame is fixed with each other in the chassis 12 and body 2, and is rotated together.
The dissecting disc is an umbrella, and its central Angle is between 60 and 100o.
The separation disc of the water separator is located near the outer edge and has a number of distribution holes 11.
Oil purifier points before should be part of the hot water (from hot water pressure tank) through the inlet into the bowl, make them form a water seal area, both inside and outside the cylinder weeks then make for purification of oil purifier in the oil in the oil pump to oil inlet 7, into the bowl after flow to the bottom, then through the distribution of the plate rack 10 hole into the separation between disc, by separating plate is divided into several layers of oil with bowl high-speed rotation.
Since the outer week has formed a circle of water seal, it can prevent oil from escaping from the exit.
When the water is separated from the oil, it will run on the original water seal, so that it will be drained from the outlet through the annular space between the top 8 and the separation tube cover 5 and the gravity ring 9.
The mechanical impurities in the oil will pass through the water seal area and be thrown on the inner wall of the separator.
The net oil continuously flows through the ring channel between the plate frame and the top cover to the outlet of the oil outlet and the oil separator.
If water seal area is determined by the oil water interface, oil-water separation (shaft center) mobile throughout into the separating plate components, water seal area will be too thick, will cause the separating plate component blocks, will be oil carries a number of water droplets and tiny impurities separated out and discharge bowl with oil, reducing the separation effect.
If boundary facing mobile, on the one hand, can reduce the effect of the separation of oil from the water, resulting in the water with oil, on the other hand may destroy the water seal, cause the fuel by the outlet flow out, the oil outlet run.
The position of the oil-water boundary is determined by the inner diameter of the gravity ring.
The principle of selecting the gravity ring is that the inner diameter should be selected as far as possible without breaking the water seal.
A chart with a selection of gravity rings is usually attached to the oil separator's instructions.
 

The separation machine is mainly used to separate the mechanical impurities, it has no outlet, and it does not need to introduce water sealing water when used.
The main structure of the water purifier and the separator is the same. The difference is only:

(1) there is a circle distribution hole in the water distributor tray, and no holes in the machine;

(2) the water separator has the gravity ring and the outlet of the oil outlet and the outlet. The separator has only the outlet of the oil, which does not need the gravity ring.
Therefore, they can be exchanged only by changing individual components.
For example in (b) no panel in figure 15 (a) in the figure with a panel of 10, and (b) to the thick top 13 points of mixed plate 14 instead of (a) the purifier the top 8 in the graph and gravity ring 9,

It can be converted into a separate machine.
   

The structure and working process of oil separator have many types, but the basic structure and working process are much the same.

An example is given to illustrate the example of a self-moving slag separation machine with a - LAVAL WHPX.
The main structure is shown.
The drive mechanism of the separator is installed in the lower part of the oil separator.
The separator is driven by friction clutch (E) and turbine mechanism (D), rotating at A high speed.
The structure of separating cylinder and automatic slag discharging system for the oil separator.
It is only necessary to change the gravity ring to a separate disk.
The separating cylinder body (J) and the tube cover (F) are tightly closed with a large locking ring.
The oil distributor (D), the oil matching cone (VV) and the separator (G) are installed in the tube, and the oil flow oil distributor and oil cone are separated in the separator.
The top of the separator disc is the top plate (E), and the neck and the liquid level ring (C) form the oil cavity (aa), and the pump (U) is used to separate the net oil pump from the oil chamber.
The separated water is rising along the outer edge of the detached plate group, and the water cavity (a) overflows the gravity ring (AA) is pumped out by the centripetal pump (T).
The scattered slag is moving around the inner tube, and the slag space (ii) is collected at the outer edge of the dissecting disc group, and is discharged through the discharge orifice (I).
A ring of gravity or a separate disc is enclosed by a small locking ring (B).

) fixed on the separator lid, the locking ring also forms the upper cover of the small cavity.
Its automatic slag discharging system consists of sliding chassis (K), sliding ring (L), water distribution plate (Z) and working water system.
The working process of the oil separator can be controlled automatically or manually. The detailed description is as follows: 1.
When oil to points, starting oil purifier, stay after reaching the rated speed, open the water valve (16), seal and compensation of water inlet (P2), the water seal water distribution plate of water into a seal at the bottom of the sliding chassis water cavity (Y2).
Due to the action of the spring (O), the sliding enclosure closes the drain valve (X) and seals the water chamber to form a sealed state.
In a bowl under the condition of high speed, sliding chassis at the bottom of the pressure is greater than at the top of the pressure, so that the sliding chassis compression on the bowl cover, keep it sealed, for oil.
2.When the separator is sealed, the inlet (10) can be opened to water (if the operation is not available).
After the separation cylinder is sealed (usually with a small amount of water flowing out of the outlet (5), the oil can be imported.
Carry out normal oil separation operation.
If there is a small leakage in the sealing water during the separation process, the water valve (16) will be opened to compensate for water inlet (P2) from the sealing and compensation water inlet (P2).
3.When the slag is to be discharged, the inlet (1) stops the oil intake, the inlet (10) enters the replacement water, and the internal flushing of the separation tube is carried out and the oil is flushed, and the oil is lost when the slag is discharged and the slag is reduced.
Then open the water valve (15), open work water inlet (P2) into the water, the water distribution plate into the open water cavity (Y1), until the upper sliding ring open water pressure is greater than the lower spring (O) stretch.
At this point, the sliding ring moves downward, opening the drain valve (X), and the sealing water of the lower seal of the sliding chassis is released.
The sliding chassis is rapidly falling under the pressure of its upper part, opening the slag discharge hole.
After the discharge, if you need to continue to divide oil, you can repeat the above actions 1 and 2.
If need to stop, can stop directly.
At present, the structure and working process of the automatic slag separator used in most ships is the same as above, and it is used in combination with one controller.
The structure and working process of the alpha-laval FOPX oil separator are slightly different.
It is used in combination with EPC400 control unit, moisture sensor and drain valve.
The oil separator is opened, and the separator can be directly fed into the oil after sealing. The oil can be discharged without stopping the oil. The density of the oil can be up to 1013kg/m3.
    

3. Operation and management of oil separator.

1.The heating temperature and the amount of oil can be determined by heating the oil separator heater, reducing the viscosity and increasing the density of impurities, water and oil so as to improve the separation effect.
Oil temperature cannot be too high, lest water evaporate, destroy oil moisture interface, cause run oil.
The heating temperature depends on the quality of the oil and the boiling point of water.
The smaller the oil separator, the better the separation effect.
But for fuel, oil amount must meet the fuel consumption of the host for the lubricating oil, the cycle after the separation, oil amount is smaller, the number of circulating separation is less, therefore, can't pursue too small points of oil.
Generally speaking, the viscosity of oil is bigger, the quality is worse, the heating temperature should be increased appropriately, and the oil content should be reduced as appropriate.
Table 5-4 shows the range of heating temperature range of different oil and the percentage of the recommended maximum oil amount of oil content, which is for reference.
 

2.When choosing the best way to work on the ship, there are three kinds of working methods: single machine work: the whole flow is handled by a water dispenser.
Parallel work: two water separators work in parallel, each handling 50% of the total flow.
Series work: two oil separator in series, the former one is the water distributor, and the second one is a separate machine, each of which has to deal with the full flow.
This kind of method works best, even if the water oil moisture interface is too close, the separation effect is worse, because the back stage still has the separate machine, still can maintain the teaching score miscellaneous effect.
 

3.Operating points

At present, the automatic oil separator has been widely used in ships.
Taking the WHPX oil separator as an example to illustrate the operation management key points of the automatic oil separator.
This kind of oil purifier in addition to a EPC400 control unit, some control and detection of auxiliary components, oil purifier motor starter box, also equipped with auxiliary equipment such as pumps and heaters, they constitute a purification system.
 

1) check before starting.

In addition to check the oil purifier before starting gear box lubricating oil, brake device, bowl and switch position of friction clutch, all kinds of valve parts is in accordance with the requirements, should also check whether the heater, air source is normal, EPC400 set parameters conform to requirements.
When the above preparation is completed, the starting operation can be carried out.
 

2) starting and running.

Start the oil pump, start the oil heater heater, and then start the oil separator.
It takes about 5 minutes for the oil separator to accelerate. During the second period, it is important to observe whether the indicator of the current meter on the starter is normal, and it should be ensured that all normal noises or vibrations occur.
When the oil separator reaches the normal speed and the oil temperature is heated to the required temperature, the program switch button on the control unit can be pressed to carry out the oil separation operation.
During oil separation, it is necessary to pay attention to whether the outlet of the water outlet and the drainage hole are running oil, lubricating oil level, daily oil tank and oil level of settling oil tank, high water tank level, oil separator and operation condition of oil pump.
Pay attention to all kinds of trouble alarms, eliminate alarms and troubleshoot.
 

3) discharge

When running to the selected time, the program will automatically trigger the discharge, discharge the slag and then resume normal oil separation operation.
 

4) stop the oil separator.

When need to stop points oil, as long as the program switch button again, oil purifier automatically finish slag discharge, and then automatically stop oil purifier, and its starting switch lock 3 min, 3 min after downtime in oil purifier can't start again.
Then manually turn off the oil heater, then stop the oil pump when the oil temperature drops.
By visible, automatic oil purifier need artificial starting equipment in accordance with the starting order for the oil pump, heater and oil purifier, stop points oil at the time of the order, in contrast to the starting sequence, and the oil temperature drop after such as certain for oil pump will be stopped.
  

4. Common failure of oil separator.

1.The separation tube does not reach the specified speed.

1) the brake is not released;

2) in the friction clutch, the oil is mixed with grease and the friction film is slippery or damaged;

3) malfunction of motor or electrical equipment.
 

2.There are several kinds of reasons for the failure to supply oil for oil pumps.

The first is that the pump or pipeline problem does not produce enough low suction pressure for the following reasons:

1) the cone pin of the oil pump transmission gear is broken;

2) the pump is badly worn and the gap is too large;

3) the pump speed is too low;

4) leakage of the suction pipe;

5) the second reason is that the pump suction pressure is too low.
The reasons for this are:

6) low oil level;

7) the filter is blocked or the pipeline is blocked before the oil pump;

8) the oil temperature is too low and the viscosity is too high.
 

3.The first type of oil outlet is water seal failure to establish or damage:

1) the water seal is not added or added too little when starting;

2) the inlet valve is too fierce and the water seal is damaged;

3) the oil temperature is too high, the water seal water is evaporated, the water seal is destroyed;

4) insufficient speed to seal the water pressure;

5) the second type of fouling between the separation discs is the external displacement of the oil water interface to the separation plate.

The reasons for this are:

6) the inner diameter of gravity ring is too large;

7) the oil is not heated to the required value, and the density is large.
 

4.Slag runner

This is due to the failure of the drainage hole to be closed.
There are several reasons for the reasons for the oil discharge:

The first is that the slip ring cannot be moved up and shut off the sealing water cavity.

The reason is:

1) the small hole M1 and M2 (see figure 5-) of the separator tube are blocked and cannot be drained.

2) the spring fails under the sliding ring;

3) the plastic plug at the top of the sliding ring is not strict.
The second reason is that the lower part of the sliding chassis lacks sealing water, which may be:

4) there is no water in the high water tank;

5) blockage or serious leakage of the working water system pipe or control valve;

6) failure of the sliding chassis circumferential sealing ring.
 

The third reason is that the sliding chassis and the separation tube cover can not be tightened. The reason is:

7) failure of the main seal ring on the sliding chassis;

8) excessive wear of transmission gears and bearings causes the shaft to sink.
 

5.Can't discharge

The reason may be the lack of open working water of pressure drop moving coil, which may be:

1) there is no water in the high water tank;

2) blockage or serious leakage of the working water system pipe or control valve;

3) the water holes in the work are blocked;

4) failure of the ring seal ring on the sliding circle.
 

6.Abnormal vibration or noise occurs.

The main problem may be: 1) improper installation of the separator, loosening of the fastener, or rubbing against the machine cover and water plate;

2) the transmission machinery is damaged due to lack of oil or oil;

3) bearing excessive wear and vertical shaft sinking;

4) for oil pump card resistance or damage;

5) the friction clutch is damaged or overworn, and the quality is not uniform;

6) the slag is not clean and the slag in the separator is not equal.