Admin or K..Y_KMTB please help me!!!

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Admin or K..Y_KMTB please help me!!!

Bài gửi by mercury on 9/17/2009, 23:12

I have some problem a bout fuel oil system.?? if anybody known, please contact me as soon as posible..thanks!
1. I saw that after the fuel pump ( to supplies fuel to nozzle) has a long tube. Why the designer weren't design the direct tube ( to save the tube) while the bend tube? so what is the funtion of this design??
2. I kown that there are two types of fuel pump are using on board ship and a number method to regulating quality of fuel ( for ex: control the first perious, last perious and combine...). How many total method to regulate quality fuel and which is ther method are used the most on board??
3. During voage we can changing the fuel from DO to FO and opposite. when the ship prepare into port, we changing fuel FO-DO to easy "mano" because if we're used FO can lead to stuck fuel in the tube( from after fuel pump to nozzle) and hard for contionues starting next. Nowaday we can only used FO during the operating of ship.. Is it true?? I need more information about that problem and when we used DO to starting,why? i need detail about this reason??
4. why doesn't the fuel burning in ahead of nozzle?
5. how to the lubricating the top ring (the ring to seal burning gas don't leakge to "cacte". the lubricating oil in here can burning and making the ash( dirty)
6. Can you show me detail about the lubricating oil system, air system , fuel oil system, starting system?? i have studied to these system and know sone knowkeage but i xant to correct it and know more interesting information!!
7. In fact,with the truth system on ship, it very coplication and difficult to find it. So have you any experiance, please share to me!!!
Thank a lot!! ( Mercury!!)

mercury
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Re: Admin or K..Y_KMTB please help me!!!

Bài gửi by dungshoes on 9/19/2009, 23:14

Idea


Được sửa bởi dungshoes ngày 12/17/2009, 19:42; sửa lần 1.

dungshoes
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Re: Admin or K..Y_KMTB please help me!!!

Bài gửi by dungshoes on 9/19/2009, 23:19

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http://mkt46dh1.tk

dungshoes
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A reply for queries

Bài gửi by КЭУ-KMTB on 9/21/2009, 00:14

Dear, Mercury!
I know you are energy man, but I also realize that you made too much errors when writing, both spelling and grammar. Because of this, sometimes I do not clearly understand what you want to talk about. I thing if we want to improve English skill, firstly we need try correctly write and speak. Do not worry! We try together, step by step.
About questions, sometimes they did not receive a reply, please, do not surprise! May be, they belong to basic knowledge (that introduced in the lessons). Now, your queries will be said as below:
1. There is a metal pipe that connects the fuel injection pump (FO pump) with the fuel injection valve (FO valve), this pipe is known as the high pressure pipe. In fact, FO pump and FO valve can be made in one piece without high pressure pipe (bơm cao áp liền vòi phun). However, this type of FO pump-valve is only suitable for small size and high speed engines. For large-medium and low speed engines, normally the FO valves are fitted in the cylinder covers, while the camshaft (which drives the FO pumps) are arranged on the framework at a certain distance. Because of this, it must be provided with high pressure pipes between FO pumps and FO valves. And lastly, of course, the high pressure pipes are bent to reduce the pipe resistance.
2. There are two types of FO pump that are being used on board ships: Bosch type FO pump and valve type FO pump. To adjust the fuel oil quantity that is injected into the cylinder in the working cycle, one of the following methods can be used:
- To change the effective stroke of the plunger (piston of the FO pump);
- To change the full stroke of the plunger (by using fuel cam with tapered surface);
- To keep constant of effective stroke of the plunger but discharge out an amount of fuel oil from the barrel (cylinder of the FO pump) through a throttle;
- To control the supplying process of fuel oil to the FO pump;
- To adjust the fuel oil quantity to the FO valve by the injection control unit (used for indirect fuel oil supplying systems).
Nowadays, method of changing the effective stroke of the plunger is widely used for almost direct fuel oil supplying systems, while method of using the injection control unit is the first selection for indirect fuel oil supplying systems (with the common rail system) on modern ships.
Depending on the construction of the FO pump, the effective stroke of the plunger can be changed as follows:
- By changing the beginning moment of the fuel injection of the FO pump;
- By changing the ending moment of the fuel injection of the FO pump;
- By changing both the beginning and the ending moment of the fuel injection.
In which, the first is normally used for high speed main engines, the second for low speed main engines and generator engines, and the last for medium speed main engines.
3. Maneuvering (điều động tàu) is one of the unstable regimes of the main engines. In maneuvering regime the main engine need change its working condition (such as “stop”, “start” or “reverse”) and normally run at low load and speed according to the order of the Bridge. At such condition, the fuel injection pressure of the FO pump will be dropped. So it is difficult to spray the fuel oil in the form of fine mist, as well as to distribute the fuel oil over the volume of the combustion chamber, and to mix the fuel oil with the compressed air in the cylinder. Besides, the compression temperature and pressure in the cylinder (Pc, Tc) will be decreased. These lead to that the ignition of the mixture in the cylinder will become harder and the engine may be suddenly stopped as a result. Because of those reasons, to increase reliability of this regime, diesel oil (DO) should be used when maneuvering.
In fact, FO quite can be used when maneuvering if it is appropriately heated to reduce the viscosity. However, when the engine stop for a long time (one day or more), FO will cause stick the nozzle of the FO valve. So the fuel oil cannot be injected, even the fuel cam or the high pressure pipe may be broken when the engine starts in the next time. Because of this, the fuel oil must be switched over DO at least 45 minutes before stopping the main engine.
For large-low speed engines such as MAN-B&W or SULZER, with a special construction of the FO valve, the fuel oil can be circulated through the FO valve even when the engine stops (the FO pump does not operate). So it is not necessary to switch FO over DO when the ship is going to berth and to lie at the port for some days. In this case, the fuel oil system is provided with a FO circulating pump, and the FO must be circulated and heated like the engine is running. For these kinds of engine, DO is only used for maneuvering when the ship is going to lie in a long time such as for overhauling or docking.
4. I do not clearly understand your mind, perhaps your mind means “Why is the fuel oil not burned in the fuel chamber of the nozzle?” Yes, of course! Firstly, there is no compressed air and burning gases in the fuel chamber because when the FO valve is injecting, the injection pressure is much higher than compression pressure. On the other hand, when finishing the injection, the needle will tightly close on the seat and separate the fuel chamber of the nozzle with the combustion chamber. Secondly, the temperature of the fuel chamber is much lower than ignition temperature of the fuel oil.
5. For small size-high speed engines, the cylinder liner is lubricated by splashing LO from the crankpin journal due to the centrifugal force. When the piston is going up and down, LO will be distributed on the surfaces of the liner and the piston rings. By this way the first ring will be lubricated. Of course, the first ring is badly lubricated, so the surfaces of the first ring and the liner (at the position of the first ring when the piston is on the TDC) are most worn.
For large engines with a long piston stroke, the cylinder liner is lubricated by Bosch type pump through the drilled holes on the cylinder wall; these holes are connected to each other by wave (or straight) grooves. When the first ring comes up and covers the holes, the LO will be supplied into the liner surface until the last ring comes over them (this matter was mentioned in the lessons).
6, 7. If you want to know more detail about these systems, you need post up them here and somebody can help you.

Thank for attention!

КЭУ-KMTB
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Re: Admin or K..Y_KMTB please help me!!!

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