Marine Boiler Working, Construction, Combustion & Operation PDF

Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Lesson 102 ~ 105 Thermodynamics and Heat transmission In marine boilers,...

Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Lesson 102 ~ 105 Thermodynamics and Heat transmission In marine boilers, thermodynamics and heat transmission are closely related concepts that govern the operation and efficiency of the boiler system. Thermodynamics: Thermodynamics is the branch of physics that deals with the relationships between heat, work, and energy. In the context of a marine boiler: Energy Conversion: A marine boiler operates based on thermodynamic principles. It converts the chemical energy stored in fuel into thermal energy through combustion. This thermal energy is then used to convert water into steam. First Law of Thermodynamics: This law states that energy cannot be created or destroyed, only transformed. In a boiler, this means that the total energy input (from fuel) must be equal to the energy output (as steam and other forms of heat). Second Law of Thermodynamics: This law deals with the efficiency of energy conversion processes. It sets limits on how efficiently energy can be converted from one form to another. In a boiler, it helps define the maximum possible efficiency. Thermodynamic of boiler https://www.youtube.com/watch?v=nxvav0Ijd4E Heat Transmission: Heat transmission involves the movement of heat from one location to another. In a marine boiler, heat transmission is a critical aspect of the system's operation: Page 1 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Combustion: Heat is generated through the combustion of fuel in the boiler's combustion chamber. The hot gases produced during combustion transfer their heat to the surrounding boiler components. Heat Exchange: The heat generated is transferred to the water in the boiler through a heat exchanger. This is typically a system of tubes or coils that allow the hot gases to come into contact with the water. Steam Generation: As the water absorbs heat, it undergoes a phase change, turning into steam. This steam is then collected and used for various applications on the ship. Efficiency Considerations: Efficient heat transmission is crucial for maximizing the energy output of the boiler system. Insufficient heat transfer can lead to lower steam generation rates and decreased overall efficiency. Control and Regulation: Understanding heat transmission is essential for maintaining proper control of the boiler. This includes regulating factors like fuel input, air supply for combustion, and water flow rates to optimize heat transfer. Materials and Design: The choice of materials and design of the heat exchange surfaces in the boiler play a significant role in ensuring effective heat transmission. In summary, thermodynamics governs the fundamental principles of energy conversion within a marine boiler, while heat transmission deals with the practical aspects of how heat is generated, transferred, and utilized within the system. A thorough understanding of both concepts is essential for designing, operating, and maintaining efficient marine boiler systems. How heat transfer. In a boiler, heat transfer occurs through three main mechanisms: conduction, convection, and radiation. Here's how each of these processes is applied in a boiler: Page 2 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Conduction: Definition: Conduction is the transfer of heat through direct contact between particles of a solid material. In boilers, it primarily occurs within the boiler's metal components. Application in Boilers: The heat source, such as a burner or furnace, raises the temperature of the combustion chamber and the boiler's metal components (tubes, walls, etc.). The high-temperature metal conducts heat to adjacent areas of lower temperature, such as water within the boiler's tubes. The heat is transferred from molecule to molecule within the metal until it reaches the water, increasing the water temperature. Convection: Definition: Convection is the transfer of heat through the movement of fluids (liquids or gases). In boilers, it mainly involves the circulation of water. Application in Boilers: Water is heated in the boiler's tubes by conduction, causing it to rise due to its reduced density (hot water is less dense and tends to move upwards). As the hot water rises, cooler water from other areas moves in to take its place, creating a natural circulation loop. Natural Convection vs. Forced Convection: Natural convection relies on the buoyancy of heated water for circulation. In some boilers, pumps may be used to facilitate forced convection, enhancing heat transfer rates. Radiation: Definition: Radiation is the transfer of heat in the form of electromagnetic waves. It does not require a medium to travel through, and can occur in a vacuum. Page 3 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Application in Boilers: Radiant heat is emitted from the high-temperature surfaces of the combustion chamber, furnace walls, and other hot components within the boiler. This radiant energy is absorbed by cooler surfaces, including water tubes and other boiler components, which in turn increases their temperature. Radiant Super heaters and Re-heaters: In some boiler designs, radiant super heaters and re-heaters are positioned in the path of high-temperature flue gases to further absorb radiant heat energy. It's important to note that in practical applications, all three modes of heat transfer (conduction, convection, and radiation) often work together, contributing to the overall efficiency of the boiler system. The specific design and arrangement of components within a boiler are optimized to maximize heat transfer and energy efficiency. ****************** Page 4 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Lesson no 106~109 Fundamental of Marine Boiler The fundamentals of a boiler encompass its basic components, working principles, and safety considerations. Here's a concise overview:- Definition: A boiler is a closed vessel that uses heat energy to convert water into steam, which can be used for various applications. Purpose: Boilers are used for heating, power generation, and process applications across industries like power plants, industrial facilities, ships, and more. Components: Furnace: Where fuel is burned to produce heat. Water Tubes/Shell: Contain water that is converted to steam. Steam Drum: Collects and distributes steam. Superheater: Raises steam temperature. Economizer: Pre-heats water using waste heat from flue gases. Safety Valves: Release excess pressure. Feedwater Pump: Moves water into the boiler. Controls and Instruments: Monitor and regulate boiler operation. Page 5 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Working Principle: Boilers operate on the principle of converting water to steam through heat transfer. Heat from the combustion of fuel (e.g., coal, oil, gas) raises the temperature of water in the boiler, turning it into steam. Heat Transfer: Conduction: Heat is transferred through solid materials (e.g., furnace walls, tubes). Convection: Heat is carried by fluid movement (e.g., water circulation, hot gases rising). Radiation: Heat is emitted in the form of electromagnetic waves (e.g., from the flame). Boiler Efficiency A measure of how effectively a boiler converts fuel into usable energy. It's influenced by factors like combustion efficiency, thermal efficiency, and losses. Heat Balance Theory in a Boiler: Page 6 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Introduction: A boiler is like a heat engine that converts fuel energy into useful work, in this case, producing steam. Energy Input: The process starts with the introduction of energy into the boiler, typically in the form of fuel. This can be coal, oil, natural gas, or other sources. Combustion: The fuel is burned in the furnace, releasing heat energy. This heat raises the temperature of water surrounding the combustion chamber. Heat Transfer: There are three main methods of heat transfer: Conduction: Heat is transferred through solid materials, like the walls of the furnace and the boiler tubes. Convection: Heat is carried by the circulation of fluid, such as water and steam, and by the movement of hot gases. Radiation: Heat is emitted in the form of electromagnetic waves, primarily from the flame. Water to Steam Transformation: As water absorbs heat, it undergoes a phase change, turning into steam. This process happens in the water tubes. Steam Quality and Superheating: The quality of steam (i.e., how "dry" it is) is an important factor. Superheating involves raising the temperature of steam above its saturation point. Energy Output: Page 7 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. The goal of the boiler is to produce high-quality steam at a certain pressure and temperature, which can be used for various applications like power generation or heating. Heat Losses: Not all the energy from the fuel is converted into useful work. There are always losses, which can occur through radiation, convection, incomplete combustion, and other factors. Efficiency: The efficiency of a boiler is a measure of how effectively it converts fuel energy into steam. It's calculated by dividing the useful output (steam energy) by the input (fuel energy). Balancing the Equation: In an ideal scenario, the energy input should be equal to the energy output plus any losses. This is known as a heat balance. Importance of Heat Balance: Maintaining a heat balance is crucial for optimizing boiler performance. Any discrepancies can indicate inefficiencies or problems in the system. Applications: Understanding the heat balance theory helps operators and engineers make adjustments and improvements to enhance the efficiency and safety of the boiler. Safety Considerations: Safety valves prevent excessive pressure. Water level indicators prevent dry firing. Pressure and temperature gauges monitor conditions. Page 8 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Regular maintenance and inspections are critical for safety. Water Treatment: Proper water treatment prevents scale formation, corrosion, and other issues, prolonging the life of the boiler. Applications: Boilers are used in power plants, industrial processes, heating systems, and propulsion in ships. Environmental Impact: Efforts are made to improve boiler efficiency and reduce emissions for environmental sustainability. Types of Boilers: Fire-tube and water-tube boilers are the main types, each with distinct designs and applications. Combustion Process: Fuel is burned in the furnace, releasing heat energy, which is absorbed by water, producing steam. Maintenance and Inspection: Regular maintenance, cleaning, and inspections are essential to ensure safe and efficient operation. These fundamentals provide a foundational understanding of boilers and their importance in various industries. They are crucial for engineers, operators, and technicians involved in boiler operations. A marine merchant ship boiler is a specialized type of boiler designed for use on ships, and it plays a crucial role in providing power for various onboard systems. Here are the fundamentals of a marine merchant ship boiler: Page 9 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Purpose of Marine Merchant Ship Boiler: The primary purpose of a marine merchant ship boiler is to generate steam, which is used for various applications onboard the ship. This includes Propulsion: Steam is often used to drive turbines or engines that propel the ship through the water. Power Generation: The steam can also be used to generate electricity for lighting, machinery, and other electrical systems. Heating and HVAC: Steam can be used for heating purposes and in the ship's heating, ventilation, and air conditioning (HVAC) system. Hot Water Supply: Some boilers are equipped to provide hot water for general use. Environmental Considerations: Emissions Control: Boilers must meet emissions standards to minimize environmental impact. Efficiency Measures: Implementing fuel-efficient practices helps reduce the environmental footprint. Future Trends: Advancements in technology and environmental awareness are leading to the development of more efficient and environmentally-friendly boiler systems for merchant ships. Remember:--- specific procedures and requirements may vary depending on the type of ship and the boiler's design. Always refer to the manufacturer's guidelines Page 10 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. and follow the ship's specific maintenance schedule. Ship engineers are typically extensively trained in boiler operation and maintenance. Types of Merchant Ship Boilers: Fire-Tube Boilers: Fire-tube boilers have a relatively simple design. They consist of a large metal tube or shell that contains the water being heated and a series of tubes or flues that carry the hot gases of combustion through the water space. These boilers are typically used for smaller ships and applications with lower steam requirements. Water-Tube Boilers: Water-tube boilers are more complex and efficient. They have small tubes filled with water and larger ones carrying hot gases. These boilers are preferred for larger ships as they can handle higher steam capacities. Alborg water tube vertical boiler https://www.youtube.com/watch?v=d6yN5o42MFQ Page 11 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Smoke tube boiler https://www.youtube.com/watch?v=5SUOfVp8Zm4 Page 12 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. *************** Page 13 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Lesson 109~116 Boiler Construction & Mountings Boiler Components: 1) Furnace: This is the area where fuel (typically oil or gas) is burned to produce heat. The heat is then transferred to the water or steam. 2) Water Drum and Steam Drum: In water-tube boilers, there are usually two drums. The water drum is located at the bottom and the steam drum at the top. Water circulates between these drums, and steam forms in the steam drum. 3) Tubes: These carry the hot gases from the furnace through the water, allowing heat exchange to occur. 4) Burner: This is the component responsible for burning the fuel and creating the necessary heat. 5) Safety Valves: These are crucial for maintaining safe pressure levels within the boiler. They release excess pressure to prevent accidents. 6) Control Systems: Modern boilers are equipped with sophisticated control systems that monitor various parameters like pressure, temperature, and fuel flow to ensure safe and efficient operation. 7) Feed water System: Page 14 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. This system supplies water to the boiler, ensuring a constant water level is maintained. a water tube marine boiler, down comers, up risers, and fire-tube rows are essential components that facilitate the circulation of water and steam. They play crucial roles in maintaining efficient heat transfer and ensuring the safe operation of the boiler. Here's an explanation of their functions: How water flows from feed check valve and steam is produced Down comers: Function: Down comers are vertical tubes or pipes that allow water to flow downward from the steam drum (or upper header) to the lower headers and water drum. They provide a path for the cooler water, which has not yet been heated, to reach the lower parts of the boiler for further circulation and heating. Importance: Down comers ensure that there is a continuous flow of water through the boiler. This helps maintain a consistent temperature gradient, allowing for efficient heat transfer between the hot gases and the circulating water. It also helps prevent localized overheating in the boiler. Up risers (Riser Tubes): Function: Up risers are also vertical tubes, but they serve the opposite purpose of down comers. They carry the heated water, which is on its way to becoming steam, from the lower headers to the steam drum (or upper header). Importance: Up risers play a crucial role in the circulation process by carrying the heated water upward. This allows for a continuous exchange of heat, which is necessary for the efficient generation of steam. They help maintain a steady flow of water through the boiler, ensuring that all parts of the boiler receive sufficient heat. Fire-Tube Rows: Page 15 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Function: Fire-tube rows are horizontal rows of tubes located in the combustion chamber of the boiler. They are exposed to the hot gases generated by the combustion of fuel. These tubes absorb heat from the flames and transmit it to the water circulating around them. Importance: Fire-tube rows are where the primary heat transfer takes place. They are directly exposed to the high-temperature gases, allowing for efficient heating of the surrounding water. This process ultimately leads to the production of steam. The combination of down comers, up risers, and fire-tube rows creates a circulation loop within the water tube marine boiler. This circulation ensures that water continuously moves through the boiler, absorbing heat and ultimately producing steam. Proper design and maintenance of these components are crucial for the safe and efficient operation of the boiler system on a ship. Membrane Wall: Definition: A membrane wall is a water-cooled wall made of tubes that form a barrier between the furnace (where the combustion of fuel takes place) and the water/steam-containing sections of the boiler. These tubes are typically welded together to form a continuous, tightly-sealed barrier. Function: Heat Absorption: The primary function of the membrane wall is to absorb the intense heat generated by the combustion process in the furnace. This prevents excessive temperatures in the furnace and helps protect the boiler's structural integrity. Pressure Containment: The membrane wall also provides a barrier that helps contain the high-pressure steam generated in the boiler. This is especially important in high-pressure applications to ensure the safety of the boiler system. Construction: Page 16 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. The tubes in the membrane wall are typically made of materials that can withstand high temperatures and pressure, such as special alloy steels. The tubes are arranged in a way that they form a continuous wall, providing a large surface area for efficient heat transfer. Advantages of Membrane Walls: Enhanced Heat Transfer: The membrane wall design allows for efficient heat absorption, which contributes to higher boiler efficiency. Reduced Thermal Stress: The even distribution of heat across the membrane wall helps reduce thermal stress on individual tubes, prolonging their lifespan. What is the boiler mounting? It is directly fitted to the boiler shell. They are  Safety valve  Main steam stop valve  Air vent cock  Two gauge glass level indicators  Feed check valve  Scum blow down valve  Bottom blow down valve  Salinity cock or test cock  Man whole doors. Where are air vent cock located and its purpose? The air vent cock is fitted at the top of the steam space of the boiler. Its purpose are- To release air from the boiler either filling the boiler water or raising the steam. To allow air to enter in the event of boiler cooling down or blowing down. ( to prevent vacuum effect) Page 17 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Feed water system of boiler The water feeding arrangement in a marine ship boiler is a critical system that ensures a continuous and efficient supply of water for steam generation. Here's a step-by-step explanation: Hot Well: The process starts in the hot well, which is a reservoir or tank that holds water at an elevated temperature. This water may come from various sources, including condensate returns, makeup water, and, in some cases, from the exhaust gas economizer. Feed Water Pump: From the hot well, feed water is pumped by a feed water pump. This pump provides the necessary pressure to deliver water to the boiler. Steam Drum: The feed water, whether it's preheated in hot well or feed water , is then directed to the steam drum of the boiler. The steam drum is a crucial component where water is converted into steam. It acts as a phase separator, allowing steam to rise to the top while water settles at the bottom. Boiler Furnace: In the furnace of the boiler, fuel is burned to produce high-temperature gases. These gases flow over tubes, heating the surrounding water and generating steam. The steam-water mixture then rises into the steam drum. Steam Separation: In the steam drum, any remaining water droplets are separated from the steam. The dry steam is then drawn off for use. Main Engine and Auxiliary Machinery: Page 18 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. The steam generated in the boiler is used to drive the ship's main engine for propulsion. Additionally, it can be utilized for various auxiliary machinery like COP and steam pumps , Turbo generators and other systems that require steam. Condenser: After performing work in the main engine and auxiliary machinery, the steam is directed to a condenser. The condenser is a heat exchanger that cools and condenses the steam back into water. This condensed water, known as condensate, is then returned to the hot well. Hot Well (Return):The condensed water is collected in the hot well, completing the cycle. From here, the water can be reheated and used again in the boiler. This entire process forms a closed-loop system, where water is continuously circulated, converted to steam, used for work, condensed, and returned for reuse. It's designed to maximize the efficiency and sustainability of the boiler system on a marine ship. Proper monitoring and maintenance of this system are crucial for safe and efficient ship operation. HOT WELL in close loop feed water system Page 19 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Economizer What is economizer? Economizer is a type of boiler which is installed in the exhaust passage of the main engine and where the exhaust heat energy is utilized to generate steam from distilled /fresh water. n marine main engine exhaust systems, an economizer is a heat exchanger that recovers waste heat from the exhaust gases of the main engine. This recovered heat is then used to preheat the feed water before it enters the boiler. Here's how an economizer works in a marine main engine exhaust system: Exhaust Gas Flow: After the combustion process in the main engine, hot exhaust gases are produced. These gases contain a significant amount of thermal energy. Economizer Placement: The economizer is typically installed in the exhaust gas stack, downstream of the main engine. It is positioned to allow the hot exhaust gases to pass over the external surface of the economizer tubes. Heat Exchange: As the hot exhaust gases flow over the economizer tubes, they transfer their heat to the water circulating inside the tubes. The water, which comes from the feed water system, absorbs this heat and gets preheated. Page 20 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Preheated Feed water: The now preheated feed water then continues its journey into the main boiler. Because it's already partially heated, the boiler requires less additional energy to reach the desired operating temperature and pressure. This water is normally ext. boiler circulating pump takes suction from hot well. Normally hot well has got stem coil and water temperature is maintained 80*c. The economizer serves several important purposes in the marine engine exhaust system: Improved Efficiency: By preheating the feed water, the economizer reduces the amount of fuel needed to bring the water up to operating temperature in the boiler. This leads to improved overall fuel efficiency. In summary, an economizer in a marine main engine exhaust system is a heat recovery device that captures waste heat from the exhaust gases and uses it to preheat the feed water. This process contributes to improved overall efficiency and reduced environmental impact in the operation of the main engine and associated boiler systems on a ship. Water feed system for economizer When an economizer produces steam without the main boiler firing. This situation typically occurs when there is excess heat in the exhaust gases from the main engine, and the economizer is able to generate steam using this excess energy. Here's how it works: Exhaust Gas Heat: When the main engine is running, it generates hot exhaust gases as a byproduct of the combustion process. These gases carry a significant amount of thermal energy. Economizer Location: The economizer is positioned in the exhaust gas stack downstream of the main engine. It is designed to extract heat from these hot gases. Page 21 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Heat Exchange in the Economizer: Inside the economizer, there is a network of tubes through which water flows. This water is sourced from the feed water system. The hot exhaust gases flow over the external surface of these tubes. As they pass over the tubes, they transfer their heat to the circulating water inside. The water absorbs this heat, causing its temperature to rise. In a typical marine boiler system with an economizer, the economizer is designed to preheat the feed water by utilizing waste heat from the main engine's exhaust gases. The economizer itself doesn't directly produce steam, but it contributes to the overall steam generation process. Here's how it works: Exhaust Gas Heat: The main engine generates hot exhaust gases during its operation. Economizer Location: The economizer is installed in the exhaust gas stack downstream of the main engine. Heat Exchange in the Economizer: Water from the feed water system is pumped into the economizer. As the hot exhaust gases flow over the economizer tubes, they transfer their heat to the circulating water inside. The water absorbs this heat, causing its temperature to rise. The preheated water exits the economizer and flows into the main boiler. Main Boiler Operation: Preheated Feed water first flows to boiler drum and circulating pump takes suction from steam drum and it feed to the economizer. From economizer hot Page 22 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. steam flows to main steam drum of boiler. The steam generated in the boiler is collected in the steam drum.(see drawing for better understanding) Steam Utilization: The steam generated in the economizer can be used for various purposes on the ship, even if the main boiler is not actively firing. For example, it can be used for heating systems like purifiers, hot water heater, bunker heating galley or other onboard small use processes. Note for oil tankers ship :- it’s not possible to use this economizer steam for cargo heating tank during sailing. If cargo heating is required during sailing then simultaneously you have to use same by firing main boiler. So, to summarize : the economizer preheats the feed water before it enters the main boiler. The main boiler is responsible for further heating the water to Page 23 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. produce steam. The steam is then collected in the steam drum and utilized for the ship's various systems and machinery. This process helps improve the overall efficiency of the boiler system by utilizing waste heat from the main engine, which reduces the amount of additional fuel needed for steam production. Additionally, it helps prevent thermal shock in the boiler, as the preheated water is less likely to experience rapid temperature changes. ************ What are the safety arrangements in marine boiler? 1. Safety valve 2. Low / high water level alarm 3. Too low water level alarm and shut down 4. Water level indicators 5. Pressure gauge 6. Low fuel oil pressure alarm 7. Low / high fuel oil temperature alarm 8. Flame failure alarm 9. Smoke density alarm 10. Low / high steam pressure alarm Why need to blow down the gauge glass? Gauge glass blow down is made to know the boiler and gauge glass connection is clear or not and to give the exact water level in the boiler. Boiler gauge glass blow through procedure? Shut steam and water cocks than open the drain cock. I. After draining water from the sight glass, there is nothing come out, both steam and water cocks are good in order. II. Open the steam cock side, blow out the steam. Page 24 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. III. Close the steam cock side, the steam connection is clear. IV. Open the water cock side, blow out the water. V. Close the water cock side, the water connection is clear. VI. Close the drain cock. VII. Open the water cock, water should then gradually come rise up to the top of the gauge glass. VIII. Open the steam cock, the water in the glass should fall to the level of the water in the boiler. Safety valve There is a distinction between relief valves and safety valves, and it's crucial to understand the differences. Here, I'll focus on safety valves and provide a detailed explanation of their operation and construction: Safety Valve Operation: Set Pressure: A safety valve is designed to open when the pressure inside a system exceeds a predetermined set point known as the "set pressure" or "popping pressure". This set pressure is carefully calibrated during the manufacturing process. Page 25 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Construction and operation of a Marine Safety Valve: Valve Body: The main housing of a safety valve, known as the valve body, is typically made of sturdy materials like forged steel or cast iron. It provides structural support and contains the internal components. Page 26 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Nozzle and Seat: The nozzle serves as the inlet for pressurized fluid (usually steam). The seat is a precisely machined surface that forms a seal when the valve is closed. Disc or Plug: This is a movable component that sits on the seat. It's designed to lift off the seat when the pressure exceeds the set point, allowing steam to be released. Spring Assembly: The spring assembly provides the opposing force to the pressure inside the valve. It's calibrated to ensure that the valve opens at the correct set pressure. Blowdown Ring: The blowdown ring is an additional component in some safety valves. Some boiler safety valves include a blowdown ring. The blowdown ring can raise or lower the valve seat ring and is used to control the amount of blowdown through the valve. This ring is locked by a bolt that protrudes through the valve and into the adjusting ring segments. of excess steam to escape during valve operation. Adjustment Screw: This screw allows for minor adjustments to the valve's set pressure. It can be used during installation or maintenance to fine-tune the valve's performance. Operation of a Marine Safety Valve with Blowdown Ring: Normal Operation: Under normal operating conditions, the valve is closed. The spring exerts a force on the disc or plug, keeping it seated against the nozzle. Overpressure Condition: Page 27 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. When the pressure inside the boiler or system rises to a level above the set pressure, it overcomes the force of the spring. This causes the valve to lift, unseating the disc or plug. Blowdown Ring Function: In a safety valve with a blowdown ring arrangement, as the valve opens, excess steam flows through the blowdown ring. This ring has calibrated clearances that allow a controlled amount of steam to escape. Controlled Steam Release: The blowdown ring arrangement helps control the rate at which excess steam is released. This controlled release helps prevent rapid pressure drop, which can cause water hammer or other damaging effects. Steam Discharge: The released steam exits the valve, relieving the excess pressure in the system and preventing it from reaching dangerous levels. Re-Seating: Once the pressure drops back to a safe level, the spring force reseats the valve, closing it. The blowdown ring arrangement is an additional feature that provides a level of control over the release of excess pressure. It's particularly useful in preventing the sudden release of pressure that can cause damaging effects within the boiler and associated systems. This feature is especially important in marine applications where space and equipment protection are critical considerations. What is the accumulation test of safety valves? The accumulation test shall be conducted by closing off all other discharge outlets from the boiler and operating the fuel burning equipment at maximum capacity. Page 28 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. The safety valves shall be sufficient to prevent the pressure from rising more than 3bar (34 kPa) above the maximum allowable working pressure of the boiler. Blow Down of boiler Blowdown is a critical maintenance procedure for boilers, even when they are in use. It involves the controlled discharge of water from the boiler to remove impurities and maintain water quality. Performing blowdown while the boiler is in operation helps prevent the buildup of harmful substances, such as scale and sludge, which can lead to reduced efficiency and potential damage to the boiler. Here's a step-by-step procedure for blowdown while the boiler is in use: Safety Precautions: Before initiating blowdown, ensure all necessary safety precautions are taken. This includes wearing appropriate personal protective equipment (PPE) and following established safety procedures. Continuous Monitoring: Continuously monitor the boiler's water level, pressure, and other operating parameters to ensure they remain within safe limits throughout the blowdown process. Safety for Blowdown Valve: Identify the blowdown valve designated for continuous blowdown. Two valves in series are typically located at or near the bottom of the boiler. Another two valves are fitted in serious fitted at the bottom plate form of E/R. Idea is it should be below water line of ship. Open Blowdown Valve Partially: Slowly open the blowdown valve to initiate a controlled discharge of water. The flow rate should be carefully regulated to prevent excessive water loss or sudden changes in boiler water level. Monitor Water Discharge: Page 29 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Observe the outflow of water from the blowdown valve. Pay attention to any signs of excessive foaming, high levels of impurities, or unusual conditions. Duration of Blowdown: The duration of continuous blowdown will depend on factors main reason to remove the chlorides from Boiler water apart from that such as boiler size, water quality, and operating conditions. It is typically carried out for a few minutes to ensure effective removal of impurities. Insure permission is taken from Bridge to avoid accidents. Controlled Discharge: Maintain a controlled flow of water throughout the blowdown process. Avoid abrupt changes in flow rate, as this can affect the boiler's water level and pressure. Close Blowdown Valve: Once the desired duration of blowdown is achieved, close the blowdown valve gradually to stop the discharge. Monitor Boiler Parameters: After blowdown, closely monitor the boiler's water level, pressure, and other operating parameters to ensure they return to stable conditions. Adjust Blowdown Frequency: Depending on water quality after doing chloride tests and general operating conditions, adjust the frequency of continuous blowdown to maintain optimal boiler performance. Document Blowdown: Keep a record of the blowdown procedure, including details like the volume of water discharged, duration of blowdown, and any observations made during the process. Page 30 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Performing continuous blowdown while the boiler is in use is an important preventive maintenance practice that helps ensure the efficient and safe operation of the boiler system on board a ship. It contributes to maintaining water quality, preventing scale buildup, and extending the lifespan of the boiler. ************ Lesson 117~119 Combustion in Boiler Basic line of combustion In Marine Boiler Air is supplied to the boiler furnace to enable combustion of the fuel to take place. A large surface area between the combustion chamber and the water enables the energy of combustion, in the form of heat, to be transferred to the water..... Marine boilers currently burn residual fuels ,< 0.5 % Sulphur. Page 31 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Page 32 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. **************** Lesson 120~124 Operation Of marine Boiler  Start-up and Shutdown: Proper procedures must be followed during start-up and shutdown to ensure the boiler operates safely and efficiently. It is to note that the following steps may not apply to all types of boilers and each boiler requires some additional steps to be followed as per its system design. However, the basic steps remain the same:  Ÿ Ensure that the vent valve on the boiler is open and check there is no pressure in the boiler.  Ÿ Check that the steam stop valve is closed. Page 33 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng.  Ÿ Check that all the valves for fuel are open, and let the fuel circulate through the system until it comes to the temperature required by the manufacturer recommendation.  Ÿ Check and open the feed water valves to the boiler and fill the water inside the boiler drum to just above the low water level. This is done because it is not possible to start the boiler below the low water level due to safety features that prevent the boiler from Firing. Also, the level is not filled much because if filled too much, the water inside the boiler might expand and over pressurize the boiler.  Ÿ Start the boiler in automatic mode. The burner fan will start the purging cycle which will remove any gases present in the furnace by forcing it out through the funnel.  Ÿ After the pre-set purge time the pilot burner will ignite. The pilot burner consists of two electrodes, through which a large current is passed, via the transformer, producing the spark between the electrodes. The pilot burner is supplied with diesel oil and when the oil passes over, the former ignites.  Ÿ the main burner which is supplied by heavy oil catches fire with the help of the pilot burner.  Ÿ Check the combustion chamber from the sight glass to ensure the burner has lit and the flame is satisfactory.  Ÿ Keep a close eye on the water level as the pressure increases and open the feed water when the level of water inside the gauge glass is stable.  Ÿ close the vent valve after the steam starts coming outside.  Ÿ Open the steam stop valve.  Ÿ Once the working steam pressure is reached, blow down the gauge glass and float chambers to check for the alarms. Shutting down a boiler Page 34 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng.  Ÿ If the boiler is needed to be stopped for a longer duration for maintenance or opened up for the survey, change the fuel to distillate fuel.  Ÿ If a separate heating arrangement for heavy oil is present then there’s is no need to change over to distillate fuel and the oil is kept on circulation mode.  Ÿ Stop the boiler automatic cycle.  Ÿ Close the steam stop valves.  Ÿ Close the boiler feedwater valves.  Ÿ when the boiler pressure is just reduced to over atmospheric pressure the vent valve is kept open to prevent vacuum formation inside the boiler. ************ Lesson 118~124 Operation of boiler Firing and shut down of boiler a boiler was never so easy. Firing Boiler – When the boiler is started, the lighten-up rate of the boiler must not be accelerated too much as this might cause an unnecessary over strain of the boiler material by quick and uneven temperature rises. Page 35 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Burner and ignitor of Pilot or D/O burner Fuel oil control vale on Boiler It might be necessary to perform a number of start/stop sequences to reduce the lighten-up rate. At the commissioning start-up of the boiler and after any repair work of the refractory, it is very important to further reduce the lighting-up rate. This is because the new refractory still contains a small amount of water. When heated the water vaporises and expands which might cause fissures and cracks in the refractory. The burner must therefore only be operated at minimum load and in intervals of 1-2 minutes for the first hours. Between each operation interval the burner should remain stopped for approximately 8-10 minutes. Following detail explains Firing and shutting down boiler during normal and emergency working conditions. Precautions on Firing Boiler Before start-up of the boiler plant, following general work and check procedures must be considered. Page 36 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Check that the main steam valve, by-pass valve and circulation valves if provided, scum valve, and blow-down valves are closed. Open the feed water valves and the air valve. Fill the boiler with feed water to approximately 50 mm below normal water level. The water level rises due to expansion when the boiler is heated. If the temperature difference between the boiler and feed water exceeds approximately 50ºC, the boiler must be filled very slowly. When filling a pressure less boiler, the shut-off valve after the feed water pump must be throttled. Otherwise the pump motor will be overloaded. Check the water level in the water level gauges. Check frequently during the complete start-up. The water level gauges should be blown down several times to ensure a correct indication. Check that the water level control system is connected and operational. Check the oil system and start the fuel oil supply pump. Pre-heat the fuel oil if the burner should operate on heavy fuel oil. Check the burner and the safety functions according to the manufacturer instruction. Firing Boiler and Pressure Rise The following work procedures must be followed during start-up of the boiler. Check that the gauge board valve and pressure gauge valves are opened. Check that the air valve is open if the boiler pressure is below 1.0bar. Start the burner on manual control and on low load. Check that the water level does not rise too high during the pressure rising period. Drain via the blow down valves if the water level is too high. If the air valve was opened close it when only steam blows out. A pressure reading should be indicated on the boiler pressure gauge before the air valve is closed. Tighten all covers such as manholes, hand holes, inspection doors, etc. during the pressure rising period. If required, check all flange joints on the plant. Page 37 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Change to automatic control of the burner when the boiler pressure is 0.5 bar lower than the working pressure of the boiler. Open the by-pass valve slowly to heat-up and pressurize the steam system. If the boiler is not provided with a by-pass valve, the main steam valve should be used to heat-up and pressurize the steam system. Open the main steam valve and close the by-pass valve. Open the valves to the steam consumers carefully in order to avoid water chocks. When the boiler is in normal operation, check that the water level control system and the gauge board functions are fully operational. After 3-4 weeks in operation, mud and deposits in the piping system may have accumulated in the boiler water. This may cause level variations which disturb the steam generation, and it is therefore recommended to blow down the boiler. It should then be inspected, cleaned, and refilled with boiler water. Shutting down Boiler Normal boiler shut down If necessary, the boiler can be shut down at any load without special preparations. When the boiler is stopped, sudden temperature and pressure drops should be avoided as they might expose mountings, pipe lines, and the boiler plant to inadmissible temperature gradients. When minimum load is obtained, stop the burner. Keep the water level at normal level until the boiler stops producing steam. Stop the feed water pump and close the feed water valves. Close the main steam valve. Emergency shut down Page 38 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. The boiler must be taken out of service immediately if parts of the heating surface have been glowing or the boiler shows recognizable deformations. The supervising authorities must be informed, and the boiler must not be used until approval from these authorities is available a substantial loss of water is noted the feed water system is unable to provide the necessary amount of feed water, e.g. due to failure of parts the safety valve cannot function sudden cracks or damage are noted in the refractory, and if steam or moisture is coming out of the refractory oil in the feed water is detected too high salinity level is detected. If an emergency shut down must be carried out, the fuel supply should be stopped. The main steam valve should be closed gradually, and the boiler must be cooled. The safety valves must not be operated. Parallel working boilers should be disconnected at once. Stop for repair or inspection The following describes the measures to be taken when the boiler is shut down for repair or inspection. Clean the boiler from soot with water. Operate the burner for at least 15 minutes after the soot removal to dry out the remaining water. Stop the boiler as mentioned previously. Check the furnace and the pin tubes with regard to cleanliness. Empty the boiler from water and clean it. Check if lime stone appears. Check and clean the outer fittings. Change gaskets where required. Clean the feed water tank and feed water pipes. Clean and grease the bearings of motor, pump, and fan. Check and align the burner, if necessary. Check that the necessary spare parts are available. Order complementary parts in time. It is of extreme importance that the boiler is NOT operated without water when the oil burner is in operation, e.g. due to disconnection of the water Page 39 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. level safety devices. This will immediately cause complete breakdown of the boiler. In small pressure ( 7 bar or kg/cm2) boilers on ships such as container and bulk carriers, the boiler is kept continuously warm to meet pressure requirements. It starts and stops frequently, a practice commonly observed when the ship is at berth or anchored. Optimizing Combustion Efficiency: o Pre-Heating Air: Some systems may incorporate pre-heating of combustion air to further enhance efficiency. o Optimizing Fuel-Air Ratio: During purging, the air-to-fuel ratio is carefully controlled to ensure that the correct mixture is achieved for efficient combustion. *************** Lesson 5.2.1 Maintenance in marine Boiler  Water Treatment: Page 40 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Water used in boilers needs to be treated to prevent corrosion, scale formation, and foaming.  Regular Inspection and Testing: Boilers must undergo regular inspections to check for signs of wear, corrosion, and other potential issues.  Cleaning: Periodic cleaning of the boiler's internal components is necessary to remove deposits and maintain efficiency.  Safety Measures: Safety is paramount. Crew members should be trained in boiler operation and be familiar with emergency procedures. Remember: specific procedures and requirements may vary depending on the type of ship, the boiler's design, and local regulations. It's crucial to refer to the manufacturer's guidelines and follow the ship's specific maintenance schedule. Additionally, ship engineers are typically trained extensively in boiler operation and maintenance. Why need to blow down the boiler water? Boiler blow down is made to reduce the density of salt and to remove the dissolved and suspended solids, also the floating solid impurities in the boiler system. If there are not removed from the boiler water system, foaming, priming, corrosion will occur in the boiler steam space and feed water system. Why Purging is Important in Marine Boilers? Purging is crucial in marine boilers for several key reasons: I. Safety: It removes potentially flammable or explosive gases from the system, reducing the risk of accidents during ignition. II. Efficiency: Purging ensures that the combustion chamber is free of unwanted substances, allowing for efficient and clean burning of fuel. Page 41 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. III. Corrosion Prevention: It helps remove corrosive gases and contaminants, which, if left in the system, could lead to damage over time. IV. Environmental Compliance: Effective purging minimizes emissions, ensuring compliance with environmental regulations. to prevent of entry into the boiler of foreign matter such as oil, waste, mill scale, FeO, Cu, Sand, etc. General but routine inspection of boiler The boiler maintenance should always be executed with skill and in accordance with valid rules and regulations from the authorities, and below are given some recommendations for periodical inspections and maintenance Daily Operation checks During normal operation of the boiler some work and check procedures have to be considered every day.  Check the boiler steam pressure and the water level.  Check that the feed water control system is operational.  Check the boiler water condition and make necessary countermeasures with regard to the feed and boiler water treatment. If necessary blow-down the boiler.  Check the function of the oil burner at different capacities through the inspection holes on the boiler.  Check the flue gas temperature after and/or the draft loss across the boiler. If either the temperature or the draft loss is too high, the pin-tube section must be cleaned. Weekly Routine Checks o Blow down gauge glass o Boiler water testing (In case of contaminated boiler water or insufficient water treatment, the blowing down of the water level glasses must be done more often.). Repeat this operation when required according to the boiler water tests. Page 42 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. o Perform scum blow out by means of the scum valve when required. The scum blow out must be carried out until the drained water is clean. o Check the safety water level device. Depending on the boiler water tests blown-down the boiler. Open the blow-down valves quickly for a few seconds, and then close and open again for about 5-10 seconds. Monthly Routine Checks  Test all stand-by pumps.  Check all boiler mountings for damage or leaks and repair/replace if necessary.  Check the function of the high steam pressure switch by lowering the set point or by raising the steam pressure, e.g. by closing the main steam valve slowly. The burner must stop automatically.  Inspection of Furnace  The furnace should be inspected at least twice a year. During this inspection the following issues should be taken into consideration:  Check for cracks at the refractory lining and that the furnace walls are free from excessive soot deposits.  Examine carefully the area opposite the burner. Too much soot deposits indicate that the burner should be adjusted. Inspection of Boiler Water Side The boiler water side (interior) must be carefully inspected at least twice a year. This inspection of great importance and no doubt the most important of all the maintenance measures, since it has a direct influence on the boiler longevity and on the security. At these inspections, hard deposits, corrosion and circulation disturbances can be found at an early stage, and preventive measures must be taken to avoid unexpected material damage and boiler breakdown. Page 43 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Presence of hard deposits at the furnace wall and the pin-tubes reduces their heat transfer properties and decrease the capacity of the boiler. Further, it is possible to make out if the feed water treatment has been satisfactory and if the blow-down has been carried out sufficiently. Incorrect feed water treatment is commonly causing hard deposits or corrosion. Insufficient blow-down will cause sludge deposits in the tubes and accumulation of sludge in the bottom of the boiler. If hard deposits are not removed, it may lead to overheating in the boiler plate material which is exposed to the flame in the furnace wall area. This may cause material damages. Incorrect feed water treatment does not always lead to hard deposits. For example, a too low or too high a pH-value may give an electrolytic reaction, causing corrosion in the boiler. When the boiler interior is inspected, examine all parts carefully and be attentive to deposits, corrosion and cracks. It is advisable to pay special attention to this inspection. Procedure and Remarks for Inspection Shut off the boiler and allow it to cool (below 100°C). The boiler should NOT be depressurized by lifting the safety valves and then filled with cold feed water since the stress induced by too rapid cooling may cause damage. Empty the boiler and close all valves. If the boiler is connected to a second boiler, check that the valves between them are closed. Unscrew and remove the manhole hatch(s) on the boiler and enter the boiler when it is sufficiently cold. Check the welding in the boiler. A careful examination should be carried out with respect to any possible corrosion or crack formation. Special care should be taken to the water line area in the pressure vessel where oxygen pitting may occur. Page 44 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. If deposits are found to be forming in the boiler tubes, the boiler should be chemically cleaned. It is advisable to consult a company of cleaning specialists who will examine the boiler deposits and treat the boiler accordingly. After chemical treatment the boiler should be blown-down at least twice a day for approximately one week. This will ensure that excessive sludge deposits due to chemical treatment do not collect in the bottom of pressure vessel. Contamination in water If the boiler is contaminated with foreign substances like oil, chemicals, corrosion products etc., it is very important to act immediately to avoid damages to the boiler. Layers of thin oil films, mud, etc. exposed to the heating surfaces causes a bad heat transfer in the boiler, leading to overheating followed by burned out pressure parts. In order to remove such contamination, a boiling out or acid cleaning have to be performed immediately. Corrosion products from the pipe system or insufficient boiler water treatment may result in corrosion in the boiler itself. It is therefore important to observe that such circumstances do not occur in the system. *********** Boiler water treatment Page 45 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Contamination in water If the boiler is contaminated with foreign substances like oil, chemicals, corrosion products etc., it is very important to act immediately to avoid damages to the boiler. Layers of thin oil films, mud, etc. exposed to the heating surfaces causes a bad heat transfer in the boiler, leading to overheating followed by burned out pressure parts. In order to remove such contamination, a boiling out or acid cleaning have to be performed immediately. Corrosion products from the pipe system or insufficient boiler water treatment may result in corrosion in the boiler itself. It is therefore important to observe that such circumstances do not occur in the system. Several chemicals can have detrimental effects on boiler water when not properly controlled or treated. Here are some examples: Corrosive Compounds:  Oxygen: Oxygen can cause corrosion of metal surfaces in the boiler, leading to pitting and rusting. Proper deaeration or chemical treatment is used to remove or minimize oxygen levels.  Carbon Dioxide (CO2): CO2 can form carbonic acid in water, leading to corrosion of metal surfaces. It's important to control and neutralize CO2 levels. Scale Forming Minerals: o Calcium and Magnesium Salts (Hardness): When present in high concentrations, these minerals can form scale deposits on heat transfer surfaces, reducing heat transfer efficiency. o Silica: Silica can form hard, glass-like deposits on boiler surfaces, reducing heat transfer and potentially causing overheating. o Iron: Iron can form deposits and cause fouling in the boiler system, reducing overall efficiency. o Alkalinity: Page 46 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. o Excess Alkalinity: High levels of alkalinity can lead to carryover of solids into the steam, causing damage to turbine blades and reducing overall system efficiency. Chlorides and Sulfates:  Chlorides: High chloride levels can lead to pitting and stress corrosion cracking in boiler components.  Sulfates: Sulfate deposits can form on boiler surfaces, reducing heat transfer efficiency.  Organic Contaminants:  Oil and Grease: Contamination with oil or grease can lead to foaming, carryover of solids, and reduced boiler efficiency.  Organic Acids: Organic acids can contribute to corrosion in the boiler system. Biological Contaminants: Bacteria, Algae, and Fungi: These organisms can lead to microbiological fouling, corrosion, and slime formation within the boiler system. It's crucial to implement a comprehensive water treatment program that includes proper monitoring and control of these chemicals to ensure the longevity, efficiency, and safety of a boiler system. This program should be tailored to the specific characteristics of the boiler feedwater and the operating conditions of the boiler. What is the purpose of boiler water test? To ensure that proper chemical treatment are maintained at all time. To detect the present of contaminants in the water that may be injurious to boiler and system. What are the advantages of boiler water treatment?  to prevent the scale formation in the boiler and feed system  to prevent corrosion in boiler and feed system. Page 47 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng.  to control the sludge formation and prevention of carry over with the steam.  to maintain the boiler water in alkaline condition and free from dissolved gases. Boiler Water Treatments and its purpose Proper treatment of make-up waste and boiler water is necessary to prevent scale, or other deposits, and corrosion within the boiler. The absence of adequate external and internal treatment can lead to operational upsets or total boiler failure. Where a choice is available, pre-treatment external to the boiler is always preferred and more reliable than treatment within the boiler. Obtain, and follow, instructions for feed water treatment, prepared by a competent feed water chemist who supplies treatment chemicals to your ship. Representative samples of feed water and boiler water must be analyzed frequently to ensure they are in specification. The following terms and guidelines are to be used in conjunction with the advice of a water treatment specialist Boiler water treatment Enumerate the boiler water test? Alkalinity test [Phenolphthalein ( p) alkalinity test, Total ( T ) alkalinity test (2 x P)] Chloride test 1. Condensate PH test 2. Amerzine test (Hydrazine test) 3. Excess phosphate test 4. Conductivity test (Total dissolve solids test) 5. Hardness test Page 48 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. S.No ANALYSIS RECOMMENDED USAGE COMMENTS 1 pH 10 to 11 Low pH promotes corrosion 2 Total Alkalinity 200-700 ppm Low; promotes corrosion 3 Phosphates 30-100 ppm Prevents scale formation 4 Total Hardness 0-50 ppm Prevents scale formation 5 Chlorides 60-200 ppm A measure of proper blow down 6 Total Dissolved Solids 2000 ppm Maximum High solids may cause surging 7 Sulfites 20-30 ppm A good oxygen scavenger 8 Specific Conductance < 700 micro ohms cm A measure of proper blow down 9 Oxygen <.007 mg/liter Prevents corrosion and pitting A good oxygen scavenger A measure of proper blow down Prevents corrosion and pitting Use proper water treatment to prevent the buildup of scale on the boiler. After scale has built up on the walls of the boiler it is almost impossible to remove it from the boiler. The introduction of acids in the pressure vessel is thoroughly discouraged, since virtually any solution that will chemically attack the scale will also attack the boiler metal. pH The pH value of the boiler water is a number between zero and fourteen. Values below seven are acidic, seven is neutral, and values above seven are alkaline. The pH factor is the most important factor influencing scale formation and the corrosive tendencies of boiler water. The pH should be maintained between a minimum of 10.5 and a maximum of 11.0 to prevent acidic corrosion of boiler tubes and plates, and to provide for the precipitation of scale forming salts before scale is deposited. Page 49 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Below a pH of 5.0 the water is acidic enough to dissolve the steel boiler plates. Under these conditions the steel gradually becomes thinner and thinner until its destruction. At a pH between 5 and 9.4 pitting of shell plates will occur at a rate depending on the amount of dissolved oxygen in the boiler. Dissolved Oxygen Dissolved oxygen is caused by the solubility of atmospheric oxygen in the feed water. Aeration of the feed water supply occurs in the feed water tanks which obviously aids in removal of other noxious gasses. Efficient aeration results in saturation of the water with oxygen. The majority of corrosion problems are directly related to the quantity of dissolved oxygen in the boiler water. Elimination of the corrosive effect of dissolved oxygen can be accomplished both directly and chemically. Direct or mechanical removal of dissolved oxygen is accomplished through the use of a deaerator or by heating the water to a temperature above 82 Deg Celsius. Heating the water can be done with a preheater tube installed in the return system. Chemical de-aeration is done through the introduction of specific chemicals (hydrazine) in the boiler to react with the oxygen. The dissolved oxygen content should be maintained at a minimum but at no time should it exceed 0.007 mg/l. Sulfites Sodium sulfite is generally used for the chemical removal of dissolved oxygen within the boiler water. To assure the rapid and complete removal of the oxygen entering the boiler feed water system the concentration of sulfite in the boiler must be maintained at a minimum of 20 PPM (parts per million). Solids Solids can be broken up into two categories: suspended solids and dissolved solids. Suspended solids are those which can be removed by filtration while Page 50 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. dissolved solids are in solution with the water. The best test for the determination of solids content of the boiler water is through a conductance test. The conductance value of boiler water varies by the various ionized salts present. The conductance can be used to measure the total dissolved solids in the boiler water and to serve as an accurate means of the control of solids through the use of blowdown. Another test which is sometimes used as a gauge of solids is to measure the chloride present in the boiler water. The ratio of chlorides in the boiler water to that of the feed water can be used as a means to determine the amount of blowdown required. The chloride test is unsuitable for feedwater with low incoming concentrations and the concentrations in the feedwater must be averaged over time for accuracy. High boiler solids will lead to foaming, priming, surging and carry over. These problems can be overcome by proper, daily blowdown of the boiler. Alkalinity The alkalinity of boiler water should be sufficiently high enough to protect shell and plates against acidic corrosion, but not high enough to produce carryover. A minimum value for alkalinity for adequate protection is 200 PPM. High boiler alkalinity, which is in excess of 700 PPM, should be avoided. Values higher than this can lead to embrittlement of the steel. Phosphates Phosphates are used to react with calcium hardness in the boiler water. In order for this reaction to take place it is important to maintain a pH at a minimum value of 9.50. It is desirable to keep the concentration of phosphates in the water to 30 – 50 PPM in order for complete reaction of the phosphates with the calcium hardness entering the boiler through the feedwater. Hardness Page 51 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. The hardness of water is caused by calcium and magnesium ions which will vary greatly throughout the country depending on the source of the water. In boilers the hardness of the water can cause the formation of scale and sludge or mud. The hardness must be removed in the makeup water to the return system. Total hardness should not exceed 50 PPM. Oils Every effort should be made to prevent oils from getting into the boiler water. Oil causes foaming, or combines with suspended solids to form a sludge which can cause the overheating of boiler plates. If oil does get into the boiler, the boiler should be taken out of service immediately and thoroughly cleaned. ********* Page 52 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Lesson 126~129 Automatic Boiler combustion control https://www.youtube.com/watch?v=QkUMyWw4dco Page 53 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. Practice Question 1. Explain the fundamental of thermodynamic of marine boiler? 2. Explain with neat sketch water tube boiler? 3. Explain with neat sketch working of smoke tube boiler? 4. How water flows in water tube boiler? or explain the function of various tubes in water tube boiler? 5. Explain with their purpose boiler mounting fitted on Boiler? 0r With respect to boiler explain with purpose all components of boiler? 6. Explain with simple sketch close loop feed water system? 7. Explain difference between relief and safety valve/ with simple sketch explain simple safety valve? 8. Explain with simple sketch how economizer works (water and gas flow) during main engine is running? 9. What do you understand boiler mountings, list all boiler mountings? 10. With reference to boiler explain step by step Firing of Boiler, why purging of boiler is important? 11. Explain one by one each boiler various water test done and its purpose of carrying out test? 12. Explain with sematic sketch how fuel combustion cycle works? 13. Explain with simple sematic sketch fuel and air automatic control ratio? Short questions 1. Why water treatment of boiler water required? 2. Why purging is important in Boiler? 3. How do you blow through gauge glass? Page 54 of 55 Competency 4.1.1.-.2-.3-.4 &.5 Marine Boiler Working, Construction, Combustion & Operation By Sandip Kulkarni, Ch. Eng. 4. What do you understand by boiler member wall? 5. Explain the purpose of economizer? 6. What is purpose blow down ring in boiler safety valve? 7. How the safety valve does works? 8. List the various safeties fitted in the boiler? (alarms & cut- outs) 9. List various boiler water tests? 10. How does chlorides and sulphate effects boiler performance? ***** End ***** Page 55 of 55