ICHEM

Atom / Element

• The smallest elemental unit in a sample of matter

Molecule

• Grouped unit of element which two or more of the same atoms are joined together

• Examples:

1. Oxygen gas (O2): Two oxygen atoms bonded together.

2. Nitrogen gas (N2): Two nitrogen atoms bonded together.

3. Ozone (O3): Three oxygen atoms bonded together.

4. Hydrogen gas (H2): Two hydrogen atoms bonded together. 
   
   

Fun Facts:

1. You can’t directly burn solid and liquid materials, it must undergo a gas form to burn.

Fundamental Properties of WaterGeneral Characteristics

• Definition of Water: Water (H₂O) is a transparent, odorless, and tasteless chemical compound composed of two hydrogen atoms covalently bonded to one oxygen atom. It is a polar molecule essential for all known forms of life, capable of existing naturally in solid (ice), liquid, and gas (steam/vapor) states.

• Distribution: Water covers 71% of Earth's surface, with oceans comprising 96.5% of total water.

• Human Body Composition: Makes up roughly 60% of human body mass on average.

• Physical Profile: Pure water is colorless, odorless, and tasteless; its shape adapts to its container.

• Phase Changes in 1 atm:

1. Freezing Point: 0°C

2. Boiling Point: 100°C

3. Melting Point: Above 0°C

*Take Note: Water's phase transitions depend directly on atmospheric pressure. For example, when boiling water in an elevated location where atmospheric pressure is lower, the boiling point of water decreases (requiring less thermal energy to turn into vapor).

Chemical & Physical Properties
a) Polarity and Structure

• Concept: A water molecule “H₂O” has a bent shape where the oxygen atom holds a slight negative charge “e-” and the hydrogen atoms hold slight positive charges “e+”

• Significance: This charge imbalance forms hydrogen bonds between adjacent water molecules, giving water its unique physical behavior.

• Because of Hydrogen water has adhesion and cohesion.

b) Universal Solvent

• What it means: Water dissolves more substances (polar compounds and ionic salts) than any other liquid.

• Concept: Due to its polar nature, water can pull apart and dissolve a vast array of ionic compounds (e.g., salts) and polar molecules (e.g., sugars)

• Why it matters: Because it dissolves minerals so easily, raw water carries high amounts of calcium, magnesium, and silica—the primary culprits responsible for forming scales inside steam boilers.

c) Specific Heat Capacity

• What it means: Water requires a large amount of heat energy “4.184J/g°C” to raise its temperature.

• Why it matters: It acts as an exceptional thermal medium, absorbing massive amounts of heat energy in marine boilers, cooling systems, and heat exchangers without undergoing sudden temperature spikes.

d) Density

• What is Density: Density is the measure of how much matter (mass) is contained within a given amount of space (volume). It describes how tightly packed a substance is. Objects with higher density sink in less dense fluids, while objects with lower density float. 

• What it means: Liquid water reaches its maximum density at 4°C. Unlike most substances, solid water (ice) is less dense than liquid water, allowing ice to float.

• Most substances shrink and become denser when they freeze from a liquid into a solid. Water is a famous exception to this rule because of how its molecules behave at different temperatures.

• Why it matters: In industrial and fluid mechanics settings, temperature variations alter water density, driving thermal convection currents inside boilers and cooling loops.

  • What it means: Water undergoes almost no volume change when subjected to high external pressure.

  • Why it happens: Its molecules are already packed closely together, causing powerful electron repulsions to resist any further compression.

  • Why it matters: This property makes liquid water ideal for hydraulic systems, hydro-testing pressure vessels, and positive displacement pumps, though it can also cause destructive water hammering when trapped in steam lines.

  
  f) Electrical Conductivity

  • What it means: Pure, distilled water “H₂O” is actually a poor conductor. However, because water dissolves ionic salts easily, standard water conducts electricity proportional to its dissolved mineral content.

  • Significance: Used to measure purity; high conductivity in boiler feedwater signals contamination or dangerous dissolved solids.

  • Why it matters: Conductivity measurements are used to monitor Total Dissolved Solids (TDS) in boiler feedwater and trigger blowdown procedures to prevent scale build-up.

  
  g) Cohesion and Adhesion

  • What it means:

  1. Cohesion: Water molecules stick to each other via hydrogen bonding.

  2. Adhesion: Water molecules stick to other surfaces (like steel pipes or glass).

  • Why it matters: Together, cohesion and adhesion cause capillary action and allow fluid films to form on tube surfaces during heat transfer.

e) Low Compressibility

• What it means: Water undergoes almost no volume change when subjected to high external pressure.

• Why it happens: Its molecules are already packed closely together, causing powerful electron repulsions to resist any further compression.

• Why it matters: This property makes liquid water ideal for hydraulic systems, hydro-testing pressure vessels, and positive displacement pumps, though it can also cause destructive water hammering when trapped in steam lines.

f) Electrical Conductivity

• What it means: Pure, distilled water “H₂O” is actually a poor conductor. However, because water dissolves ionic salts easily, standard water conducts electricity proportional to its dissolved mineral content.

• Significance: Used to measure purity; high conductivity in boiler feedwater signals contamination or dangerous dissolved solids.

• Why it matters: Conductivity measurements are used to monitor Total Dissolved Solids (TDS) in boiler feedwater and trigger blowdown procedures to prevent scale build-up.

g) Cohesion and Adhesion

• What it means:

1. Cohesion: Water molecules stick to each other via hydrogen bonding.

2. Adhesion: Water molecules stick to other surfaces (like steel pipes or glass).

• Why it matters: Together, cohesion and adhesion cause capillary action and allow fluid films to form on tube surfaces during heat transfer.

h) Surface Tension

• What it means: Cohesive forces at the surface layer create an elastic, film-like barrier because surface water molecules are pulled inward by adjacent molecules.

• Why it matters: High surface tension affects droplet formation in condenser tubes and steam quality; when combined with impurities or oil contamination, surface tension imbalances lead to severe boiler foaming.

Water Chemistry & Classification1) Potential Hydrogen (pH)

• Is a scale that measures the acidity or alkalinity (basicity) of an aqueous solution based on its concentration of hydrogen ions (H+) versus hydroxide ion (OH-) concentration. 

• Acidic Solutions: pH < 7 (Strong acids: pH 0–4).

• Basic/Alkaline Solutions: pH > 7 (Strong bases: pH 10–14).

• Neutral Water: pH = 7 (e.g., pure distilled water where H+ and OH- ions are equally balanced).

2) Difference Between Fresh and Salt Water

1. FreshWater

• Fresh water is naturally occurring water with very low concentrations of dissolved salts, commonly found in glaciers, lakes, rivers, and underground aquifers, making it essential for drinking, agriculture, and supporting land-based life.

2. SeaWater

• Seawater is the salty water found in Earth's oceans and seas containing high concentrations of dissolved minerals like sodium chloride, making it denser than fresh water, freezing at a lower temperature, and unsafe to drink without desalination.

Other important terms 

1) Viscocity 

•  A fluid’s resistance to flow or deformation. It is often described as the "thickness" or internal friction of a liquid or gas. 

• Low Viscosity: Flows quickly and easily because its molecules slide past each other with minimal friction (e.g., water, alcohol).

• High Viscosity: Flows slowly because strong internal molecular forces resist movement (e.g., honey, motor oil).

Boiler

• Definition: A vertical boiler is a type of steam generator in which the main shell (boiler barrel) is positioned vertically relative to the ground. Unlike horizontal boilers, it can be constructed as a fire-tube boiler (where hot combustion gases pass through tubes surrounded by water) or a water-tube boiler (where water flows inside tubes surrounded by hot gases). It is designed to produce low-to-medium pressure steam while maintaining a small, space-saving footprint.

• How It Works: A vertical boiler operates on basic thermodynamic principles involving combustion, heat transfer, and natural convection:

1. Combustion: Fuel (such as coal, wood, gas, or oil) is introduced through a fire hole onto a grate located in the furnace (firebox) at the bottom of the boiler.

2. Heat Generation: As the fuel burns, high-temperature flue gases are produced. Heavy combustion residue (ash) falls through the grate into the ashpit below.

3. Heat Transfer: The hot gases rise upward through the firebox and pass through cross-tubes or vertical fire-tubes submerged in the surrounding water. Heat transfers through the metal surfaces into the water.

4. Natural Convection & Vaporization: As the water absorbs heat, its density decreases, causing it to circulate upward (thermosiphon/natural circulation). Upon reaching its boiling point, the water vaporizes into steam.

5. Steam Accumulation & Exhaust: The generated steam collects in the steam space at the very top of the vertical shell, where it can be drawn off through a steam stop valve for use. Exhaust gases exit out of the top through a central uptake and chimney into the atmosphere.

• Application: In modern marine engineering, a vertical boiler is primarily used as an auxiliary boiler. Heavy machinery cannot run on cold fluids, so steam generated by the vertical boiler acts as a heat source to prepare systems for operation and keep shipboard services running.

1. Heating Fuel: Warms Heavy Fuel Oil (HFO) to reduce viscosity for pumping and atomization.

2. Preheating the Engine: Warms engine cooling jackets prior to startup to prevent thermal shock.

3. Heating Freshwater: Powers calorifiers for crew domestic use and assists freshwater distillation.

4. Heating Lubricating Oil (Lube Oil): Powers calorifiers for crew domestic use and assists freshwater distillation.

5. Propulsion (Older Vessels): Driven reciprocating steam engines or small turbines on older steamships.

6. Generation of Electricity: Drives small turbogenerators to produce shipboard electric power.

Issues in a Vertical Boiler

Other important terms a)  Fuels used on Board

1. Kerosene

2. Gasoline

3. Diesel

4. Heavy Fuel / Banker Fuel

b) Feed water

• Feedwater is the treated water continuously pumped into the boiler to replace water lost as steam. It consists of recycled condensed steam combined with pure make-up water, processed to remove dissolved gases and minerals that cause corrosion and scale buildup.

c) Brine / Salt-concentrated

• Is water containing a high concentration of dissolved salts and minerals.

• In a boiler context, as pure water continuously evaporates into steam, the remaining water becomes heavily salt-concentrated (brine). If left untreated, this high salinity causes severe scale formation, pipe corrosion, and thermal damage. To prevent this, the concentrated brine is discharged from the system through a process called boiler blowdown.

d) Parts of Boiler (Explained Parts Only)

1. Deaerator (or "Deaerate")

• To deaerate means to remove dissolved gases—primarily oxygen (O₂) and carbon dioxide (CO₂)—from boiler feedwater before it enters the boiler drum.

• Purpose: Dissolved oxygen causes severe pitting corrosion (rusting) inside boiler pipes, while carbon dioxide forms acid that eats away at the metal. A deaerator uses steam to heat the feedwater and strip these gases out to prevent equipment failure.

2. Scum Valve

• The scum valve (or scum blowdown valve) is a surface-mounted valve fitted near the normal working water level inside the boiler.

• Purpose: It skims off light, floating impurities such as oil traces, foam, grease, and floating debris that accumulate at the top of the boiler water. Removing scum prevents foaming and carryover (water droplets getting dragged into the clean steam line).

3. Blowdown Valve

• The blowdown valve (typically the bottom blowdown valve) is a heavy-duty valve located at the lowest point of the boiler, such as the bottom mud drum or water space.

• Purpose: It is opened periodically to forcibly discharge heavy mud, sediment, scale buildup, and dense chemical sludge that settles at the bottom. It also helps control the overall concentration of Total Dissolved Solids (TDS) and salt levels in the boiler water.

d) Sludge

• Is a thick, soft mud-like accumulation formed at the bottom of a boiler when suspended solids, mud, and precipitated mineral salts settle out of the water.

• If not removed via bottom blowdown, sludge bakes onto hot metal surfaces, blocking heat transfer and causing localized overheating and tube failure.

Engine Cooling Water Quality & Management

• Proper cooling water quality protects engine components from overheating, thermal stress, and premature failure. Poor water quality reduces heat transfer efficiency and severely damages system pipework.

• Will your water cause corrosion, rusting, and scaling?

1. What is Cool Water

• Cooling water is treated fresh water circulated through engine systems to absorb excess heat and prevent machinery from overheating. It transfers this heat away from vital components like cylinder liners and heads, usually dissipating it into seawater via heat exchangers.

Typical Marine Cooling-Water Arrangements

1. Cooling System using Fresh and Salt Water

1. Piston

(No diagram)

What to Consider in Cool Water

1) pH (Potential Hydrogen) 

• How acidic / basic your water

2) Chloride

• Indicator of seawater contamination or excessive salt content in close system

• Chloride is “900 - 1200” PM

3) Hardness

• Helps identify the tendency for scale-forming deposits

4) Inhibitor Concentration

• Confirms whether the treatment program remains effective 

5) Conductivity / Total Dissolved Solids

6) Glycol Concentration

• Applicable where antifreeze / coolant mixture are used

7) Water treatment depends on what the manufacturer design / suggestions

Key Parameter to Monitor

Physical and Chemical Properties of Fuel Oil OnboardFundamentals of Marine Fuel Oil

• Definition: A complex mixture of hydrocarbons(Hydrogen and Carbon) containing small amounts of impurities such as: sulfur, nitrogen, oxygen, metals, and other trace compounds.

• Primary Classifications:

1. Residual Fuels: Heavy fractions remaining after refinery distillation processes.

2. Distillate Fuels: Lighter fractions, refined to meet specific engine and emission standards.

• Engineering Impact: Fuel quality dictates pumping performance, purification efficiency, atomization, combustion behavior, emission levels, deposit formation, and component wear.

• Terms

1. Pump

2. Heater (Part where steam heats up fuel)

3. Purifier (Help of Centrifugal Force)

4. Atomization (Process of breaking down liquid fuel)

5. Combustion (Chemical reaction between a fuel and oxygen that releases heat and light)

6. Emission (Releasing up into the air)

7. Viscotherm (Controls viscosity “sTi” of fuel before it goes into the engine)

Detailed Fuel Oil PropertiesPhysical Properties

1. Density (kg/m³ at reference temperature):

• Used for fuel quantity calculations (bunkering) and configuring centrifugal purifier settings (gravity discs). 

• Varies inversely with temperature; must be evaluated alongside temperature changes.

2. Viscosity:

• Measures a fluid's internal resistance to flow.

• Controls pumping, heating requirements, injection, and atomization.

• Residual fuel requires heating prior to injection to lower viscosity for effective atomization.

• Too High: Impairs atomization and incomplete combustion.

• Too Low: Reduces lubrication in fuel pumps and injectors, risking seizure.

3. Flash Point:

• Lowest temperature at which fuel releases sufficient vapor to form an ignitable mixture with air.

• Critical safety parameters for storage and handling; low flash points present severe fire hazards.

• Note: Flash point is distinct from auto-ignition temperature or combustion temperature.

4. Pour Point & Cloud Point:

• Pour Point: Lowest temperature at which fuel continues to pour.

• Cloud Point: Temperature at which wax crystals first become visible. (Warning Sign)

• Essential for managing distillate fuel storage and transfer in cold-climate operations.

5. Water Content:

• Introduced via condensation, contaminated bunkers, tank leaks, or handling.

• Promotes system corrosion, microbial growth, purifier disruption, and incomplete combustion.

Chemical & Compositional Properties

1. Sulfur Content:

• Converted to sulfur oxides (SOx) during combustion; strictly regulated for MARPOL Annex VI compliance.

• Combustion products combine with moisture to form corrosive acids at reduced temperatures.

• It can it be an advantage in your piston (It reduces abrasion)

2. Acidity (Acid Number):

• Measures acidic constituents in the fuel; elevated levels increase the risk of fuel-system corrosion.

3. Stability & Compatibility:

• Stability: Ability to resist chemical/physical degradation (sludge/sediment formation) during storage.

• Compatibility: Ability to mix different fuels without causing precipitation or heavy sludge formation.

4. Ash & Catalytic Fines (Cat Fines):

• Ash: Non-combustible inorganic residue left post-combustion.

• Cat Fines: Hard aluminum (Al) and silicon (Si) particles originating from refinery processes.

• Highly abrasive; causes severe mechanical wear on fuel pumps, injectors, piston rings, and cylinder liners. (Abrasive means ma “gasgas” / scratching)

• Use purifier to remove

5. Carbon Residue:

• Lab indicator of the fuel's propensity to form carbonaceous deposits.

• High values result in carbon deposits on injectors, exhaust valves, and inside combustion chambers.

• Use purifier to remove 

6. Sediment / Total Sediment Potential (TSP):

• Insoluble matter causing filter clogging, purifier loading, and system deposits.

7. Lubricity:

• Fuel’s ability to reduce friction on contacting surfaces; vital for low-viscosity distillate fuels to protect fuel pump components.

8. Ignition Quality:

• Measures the readiness of fuel to ignite post-injection.

• Cetane index/number is used for distillates; poor ignition quality leads to delayed ignition, rough running, and excessive thermal stress.

Summary Matrix of Key Fuel Properties

Onboard Fuel Quality Control & Management Procedures

1. Bunker Receiving & Sampling:

• Collect and retain official representative drip samples (e.g., MARPOL sample) during bunkering.

• Verify Bunker Delivery Note (BDN) and test results prior to transfer.

2. Tank Management:

• Utilize settling and service tanks in sequence; regularly drain accumulated water and bottoms sediment.

• Maintain proper heating temperatures based on fuel specifications.

3. Purification & Treatment:

• Operate centrifugal purifiers continuously with correct gravity discs/settings, optimal feed rates, and recommended temperatures.

4. Monitoring & Maintenance:

• Continuously track viscosity, temperature, pressure differentials across filters, and purifier discharge.

• Avoid commingling incompatible fuels in storage tanks without prior compatibility testing.

Possible Questions

What is density and why is it important onboard?

Answer: Mass per unit volume (kg/m³) at a reference temperature. Important for verifying bunkered fuel quantity and selecting correct purifier gravity discs for effective water/solids separation.

Explain the relationship between viscosity and fuel temperature.

Answer: Viscosity decreases as temperature increases. Fuel is heated to achieve the target viscosity needed for correct atomization and injection.

Why is flash point important to marine engineers?

Answer: It is a key safety boundary indicating the fire hazard level of fuel during handling and storage.

What problems can water in fuel cause?

Answer: Causes corrosion of fuel components, promotes bacterial sludge growth, reduces heating value, disrupts purification, and leads to engine misfires or power loss.

Why are catalytic fines dangerous to diesel engines?

Answer: Aluminum and silicon particles are extremely hard and abrasive, causing rapid wear to injection pumps, nozzles, cylinder liners, and piston rings.

What is fuel stability?

Answer: The fuel's capacity to resist physical and chemical breakdown (sludge/sediment breakdown) over time in storage.

Why should incompatible fuels not be mixed indiscriminately?

Answer: Mixing incompatible fuels causes asphaltenes to precipitate, forming heavy sludge that rapidly blocks filters, overloads purifiers, and starves the engine.

Explain how sulfur content is related to emissions and corrosion considerations.

Answer: Sulfur burn produces SOx emissions (regulated by MARPOL). When combined with moisture below dew point temperatures, it forms sulfuric acid, causing cold corrosion in combustion spaces.

What is the importance of lubricity?

Answer: Prevents mechanical friction and adhesive wear inside high-pressure fuel injection pumps and injectors, particularly when operating on low-sulfur distillate fuels.

How can fuel properties influence combustion?

Answer: Viscosity and carbon residue affect atomization and deposit formation; ignition quality determines ignition delay and combustion smoothness; water/sediment causes erratic firing.