DUAL FUEL ENGINES PART 5 - DOUBLE WALL PIPE VENTILATION SYSTEM

Summary

This video script offers an in-depth study of the double wall ventilation pipe system for fuel gas supply in dual fuel engines, particularly the MEGI engine. It explains the setup, including the gas valve train, double wall pipe structure, and the flow of fuel gas and fresh air. The script details the process from the deck to the engine room, the looping of gas to cylinders, and the role of ventilation fans and hydrocarbon sensors in maintaining safety and efficiency. The presenter encourages viewers to pause and take notes, emphasizing the importance of understanding the system for operational and safety purposes.

Takeaways

• 🚢 The video discusses a double wall ventilation pipe system, specifically for fuel gas supply in dual fuel engines, using a MEGI engine as an example.
• 🛠️ The double wall pipe system consists of an inner pipe for fuel gas and an outer pipe for fresh air circulation.
• 🔍 The fuel gas enters the double wall pipe from the gas valve train located in the Cargo Machinery Room (CMR).
• 🔄 The system includes a loop where the fuel gas is first introduced into the first cylinder and then circulated to other cylinders via U-pipes.
• ⛴ The return pipe is used for startup and purging, but the gas does not return to the cargo tank after engine use; it vents out through a silencer.
• 💨 Fresh air for the system comes from the starting air system, reduced from 30 bar to 1.5 bar, and is activated by a valve when the engine starts.
• 🌬️ Ventilation is maintained by two double wall pipe ventilation fans, which pull air through the system and vent it out with flame screens.
• 🔍 The system includes hydrocarbon (HC) sensors to monitor for leaks in the inner pipe, with alarms set at 30% and a trip at 40% HC levels.
• 🔧 The airflow and gas flow in the system are in opposite directions to ensure safety and proper ventilation.
• 📈 The video script serves as a base reference for understanding the setup and function of double wall pipes in dual fuel engine systems.
• 👨‍🏫 The presenter encourages viewers to pause the video for diagrams, take snapshots, and engage with the content for better understanding.

Q & A

What is the primary focus of the video script?

The primary focus of the video script is to explain the double wall ventilation pipe system, specifically for the fuel gas supply system in dual fuel engines, using a megi engine as an example.

What is the purpose of the double wall pipe system?

The double wall pipe system is designed to safely transport fuel gas from the cargo machinery room to the engine room while also providing a continuous flow of fresh air on the outer side of the pipe.

What is the function of the gas valve train in the system?

The gas valve train is where the fuel gas supply system connects, and it is the starting point from where the fuel gas enters the double wall pipe.

How does the fuel gas flow within the double wall pipe system?

The fuel gas flows from the gas valve train into the inner pipe of the double wall system, passes through a small coffin, and then enters the engine room. It loops from the first cylinder to the other cylinders via U-pipes.

What is the purpose of the return pipe in the system?

The return pipe is used during the start-up process to clear or blow off the lines and for ventilation purposes to purge the lines. It does not carry gas back to the cargo tank after the engine.

What is the role of the blue piping in the system?

The blue piping represents the fresh air supply that goes into the outer pipe of the double wall pipe system, ensuring continuous ventilation.

Where does the fresh air for the double wall pipe system originate from?

The fresh air comes from the starting air system, which is reduced from 30 bar to 1.5 bar by a reducing valve on deck.

How are the double wall pipe ventilation fans used in the system?

The double wall pipe ventilation fans are used to continuously ventilate the system by sucking air from one side and venting it out into the atmosphere with a flame screen.

What is the significance of the hydrocarbon sensors in the system?

The hydrocarbon sensors monitor the atmosphere around the double wall pipe system, helping to detect any leaks in the inner pipe. They trigger an alarm at 30% and a trip of the main engine at 40%.

What are the safety measures in place for the double wall pipe system?

Safety measures include flame arresters on deck vents to prevent sparks from entering the system, and relief valves to handle pressure rises in the system.

Outlines

00:00

🚢 Double Wall Ventilation Pipe System for Dual Fuel Engines

This paragraph introduces the double wall ventilation pipe system used in dual fuel engines, specifically for a megi engine found on ships. It explains the basic setup of the system, including the gas valve train located in the cargo machinery room (CMR), where fuel gas enters the double wall pipe. The inner pipe carries fuel, and the outer pipe circulates fresh air. The fuel gas supply is distinguished by red piping, and the system includes a loop for distribution to multiple cylinders, with each cylinder head having a gas block. The return pipe is used for start-up and purging, not for returning gas to the cargo tank. The paragraph emphasizes the importance of understanding the flow and components of the system, and suggests viewers take a snapshot of the diagram for reference.

05:00

🌬️ Continuous Ventilation with Double Wall Pipe System

The second paragraph delves into the continuous ventilation aspect of the double wall pipe system. It discusses the necessity of fans to maintain ventilation, describing two double wall pipe ventilation fans that operate alternately. The fans take in air from the fuel entry side and expel it through vents with flame screens to prevent sparks. The paragraph also explains the role of hydrocarbon (HC) sensors in monitoring the system for leaks, with alarms set at 30% and a trip at 40% HC levels to ensure safety. The air supply comes from the main air compressors, reduced to 1.5 bar for the system, and is activated by a signal when the engine room start button is pressed. The summary concludes with an invitation for viewers to ask questions and engage with the content.

Keywords

💡Double Wall Ventilation Pipe System

This refers to a specialized piping system used in dual fuel engines, particularly in maritime applications. It is designed with an inner and outer wall, where the inner pipe carries fuel gas and the outer pipe circulates fresh air. This system is crucial for safely transporting fuel gas to the engine room while ensuring proper ventilation and preventing the buildup of potentially explosive gases. In the script, it is highlighted as the primary focus of the video, explaining how the fuel gas and air flow in opposite directions within the system.

💡Dual Fuel Engines

Dual fuel engines are engines capable of running on two different types of fuel, typically a primary fuel like diesel and an alternative fuel like natural gas. The video discusses the setup of such engines, particularly focusing on the fuel gas supply system and how it is integrated with the double wall ventilation pipe system. The script mentions that most ships with dual fuel engines would have a similar setup.

💡Fuel Gas Supply System

This system is responsible for delivering fuel gas from the storage tank to the engine. In the context of the video, the fuel gas supply system is connected to the double wall pipe, which carries the gas from the gas valve train to the engine room. The script emphasizes the importance of this system in ensuring the safe and efficient delivery of fuel gas to the engine.

💡Gas Valve Train

The gas valve train is a component in the fuel gas supply system that controls the flow of fuel gas from the storage tank to the engine. It is mentioned in the script as the starting point of the double wall pipe system, where the fuel gas enters the double wall pipe before being transported to the engine room.

💡Coffer Dam

A coffer dam is a temporary structure used to enclose an area for the purpose of water exclusion, typically used in construction projects. In the script, it is used to describe a part of the double wall pipe system that separates the engine room from the deck, ensuring that the fuel gas and air are safely contained and directed towards the engine.

💡U-Pipes

U-pipelines, or U-pipes, are fixed pipes used to connect different parts of a system, often forming a loop. In the video script, U-pipes are mentioned as part of the double wall pipe system, connecting the gas blocks of different cylinders in the engine. They ensure that the fuel gas is distributed evenly among the cylinders.

💡Hydrocarbon Sensors

Hydrocarbon sensors, also known as HC sensors, are devices used to detect the presence of hydrocarbon gases, which can be indicative of fuel gas leaks. In the script, these sensors are mentioned as being integrated into the double wall pipe system, monitoring the atmosphere for any potential leaks and providing safety measures by triggering alarms or engine trips if certain levels are reached.

💡Starting Air System

The starting air system is a part of the engine's auxiliary systems that provides compressed air to start the engine. In the video, it is mentioned as the source of the fresh air that is circulated in the outer pipe of the double wall system. The script explains that this air is reduced from 30 bar to 1.5 bar by a reducing valve before being used in the system.

💡Flame Arresters

Flame arresters are safety devices designed to prevent the ignition of flammable gases or vapors by preventing the spread of flames. In the script, they are mentioned as being installed on vents on the deck, ensuring that sparks or flames do not enter the double wall pipe system and cause a safety hazard.

💡Ventilation Fans

Ventilation fans are used to maintain a continuous flow of air in the double wall pipe system, ensuring proper ventilation and preventing the buildup of potentially explosive gases. The script mentions that there are two fans, but typically only one operates at a time, drawing air from the system and venting it into the atmosphere through a vent with a flame screen.

💡Purge Line

The purge line is a part of the fuel gas system used to clear or purge the lines of any residual gas before starting the engine or after a trip. In the script, it is mentioned as a separate line that follows the same path as the double wall pipe, venting out into the atmosphere through a silencer, ensuring that the system is safe for operation.

Highlights

Introduction to the double wall ventilation pipe system for fuel gas supply in dual fuel engines.

Explanation of the common setup in most ships with dual fuel engines.

Description of the gas valve train and its role in the fuel gas supply system.

Details on the double wall pipe's structure, with fuel inside and fresh air on the outside.

The process of fuel gas entering the double wall pipe from the cargo machinery room.

Diagram explanation for better understanding of the double wall pipe system.

Identification of red piping as fuel gas supply and its path to the engine room.

Description of the gas loop system and how it connects to the cylinders via U-pipes.

Clarification that gas does not return to the cargo tank after the engine room.

Explanation of the return pipe's function during engine start and line clearing.

Vent and purge line details, including their role in system safety.

Introduction to the blue piping as the fresh air supply in the double wall pipe.

The source of fresh air from the starting air system and its pressure reduction.

Mechanism of the automatic valve that controls air flow into the double wall pipe.

Importance of airflow direction in relation to gas flow for safety.

Role of double wall pipe ventilation fans in maintaining system ventilation.

Presence of hydrocarbon sensors for monitoring potential gas leaks in the system.

Safety protocols involving alarms and engine trips based on HC sensor readings.

Encouragement for questions and engagement with the content shared.

Transcripts

hi guys good morning so today we are

here to study about the double wall

ventilation pipe system uh the fuel gas

supply system for dual fuel engines the

one that I'm doing is a megi engine most

of the ships with dual fuel will be

pretty much the same setup a few

components here and there would be

slightly different but let's look at

this one so you can use this as your

base reference to learn and see what the

double wall ventilation pipe how it

looks and from where it starts what air

is in the double wall pipe how does it

reach the engine room and after going in

the pipes where does it go does it go to

the engine does it go to the atmosphere

got this diagram set up so please have a

look at this in fact I'd suggest that

you pause the video take a snapshot when

we refer or when I speak about the

things you guys should know what I'm

talking about once I explain this

diagram I'll take you down to the engine

room take you down to the deck let's do

this then the diagram looks good enough

so let's rock it the diagram basically

you need to understand first part that

side in this blackout line is in the CMR

the cargo Machinery room in that there's

something called the gas valve train I'm

sure you've seen the previous videos in

that fungal fuel gas supply system comes

to the gas valve train we are not

talking about the fuel the gas from

engine to now we'll be concentrating

basically on the double wall pipe what's

outside inside of a double wall inner

pipe is your fuel and on the outer side

is your air fresh air that will be

continuously circulated so the fuel gas

there comes out from that enters the

double wall pipe that starts here this

area is the deck then before going into

the engine room it goes into a small

coffin and then after that this whole

side is the engine room so basic

memorization let's do the red piping is

the gas the fuel gas fuel gas supplies

it there then we have a gas valve train

that after that comes out and the double

wall pipe starts outside the cargo

Machinery fuel gas coming out of there

ethane 380 45 degrees gas remember gas

coming in a double wall pipe cover Dam

into the engine room there's a loop and

it goes into the gas block of the first

cylinder and from the first cylinder it

is looped to the other cylinders by the

u-pipes these are not flexible pipes

these are fixed pipes all double wall

pipes each cylinder head has a gas block

like I've shown here so they are looped

into number of cylinders the gas enters

only into the first into the first

cylinder after that is just looped let's

look at the last cylinder this is

cylinder number seven as in my case so

you can see the yellow pipes are the

double wall pipes they are linked their

last loop the loop ends at the gas block

of unit number seven

and then the return pipe the return pipe

gas does not go back to the cargo tank

after the engine remember that gas does

not go back to the cargo tank after the

engine room the return pipe is only

during your start off that is when you

have to clear your lines you have to

blow off your lines or if the trip gas

trips for ventilation to just Purge the

lines okay so the purge line also

follows the same line uh through your

engine room through the coffin to the

deck and then it just goes off into a

silencer and then vents out into the

atmosphere

so that's your basic gas supply system

now we'll follow the blue pipe the blue

pipe the blue piping is your air the

fresh air that goes into the outer pipe

of this double wall pipe okay so it

comes from the starting air system the

main in the starting air system at 30

bar we get it from your main air bottles

main air compressors 30 bar is reduced

down to 1.5 bar by a reducing valve on

Deck this entire setup is on Deck but

the pipe comes from the engine room then

there is another valve automatic valve

this is uh this diaphragm is activated

only when the fuel gas system is we

press the start button in the engine

room these fans start and this valve

also gets the signal otherwise you'll be

just wasting uh compressed air into this

so This valve opens up we have air going

into the double wall pipe again this one

I will show you on deck so remember this

so this double wall pipe starts here

now again this pipe in case the pressure

Rises or it cannot cope up

this is a vent in the system and this

all the vents on Deck have wind screens

they're called as flame arresters so

that sparks don't go into the system all

of them have that

you can see them here marked here okay

so double wall now this is still single

pipe and now it enters the double wall

pipe on Deck before it goes into the

engine room

remember the gas flow and the airflow

the gas flow and the airflow are in

opposite directions Inner wall pipe goes

one way the gas in the outer pipe that

is air and the auto pipe goes the other

way so it goes the other way around

again into the Coffer Dam into the

engine into the first cylinder gas block

and then looped to the other cylinders

and coming in out

this way out into the Coffer Dam going

out here now this is what we need to

concentrate on

yes air is supplied by the system but we

need fans to keep the system

continuously ventilated so we have two

fans here they are called as double wall

pipe ventilation fans they are we can

use either one of them only one fan runs

at a time so this takes suction from

this side where the fuel enters this

take suction from this side so again

cross flow here it takes suction from

here delivers it and out again into a

vent into the atmosphere with a flame

screen this is usually above the the

cargo Machinery room or somewhere safe

location

in this pipe there are two HC sensors

hydrocarbon sensors in the pipe that I

can get the readings on my mop if you

remember the mop diagram in that we have

the HC readings there so it's pretty

simple to flow again from starting a

system going into reducing valves the

main inlet valve this is the wind system

start off the double wall pipe starts

here goes all the way cofferdam engine

room Loops into the cylinders gas blocks

Outlet back again Coffer Dam

right up here double all pipe went fence

and uh vented out remember the relief

all has to be there in system in case

the pressure Rises for some reason or

the other this has to be there and

another thing

there are two HC sensors just located in

the engine room near the gas wall pipes

in the forward side I'll show you this

one down and the outside of the engine

so I hope this was quite clear for you

guys the flow system the flow sequence

of the double wall pipe the air and

double wall pipe remember the air and

the double roll pipe is not any special

air it's just your air from your main

air compressors going through entire

system you know and then finally it's

the fans that uh pull out that suck out

the air and vended out of the atmosphere

but before vending it out continuously

there are hydrocarbon sensors two two HC

sensors that monitor the monitor the

atmosphere off the double wall pipe this

helps the pipe this helps us know that

if there are any leaks in the inner pipe

so very important at 30 we have an alarm

and at forty percent uh HC we have a

trip the main engine so it's a Sunday

and I hope I made your Sunday I did I

did make my Sunday I like to share

knowledge and by sharing knowledge we

end up gaining knowledge as well so do

shoot your questions in the comments

below do like do share do subscribe all

right take care cheers the deep sea man

out