Marine Engg Midterm Reviewer PDF

MarEngg MIDTERM REVIEWER REPORT 1: BOILER OPERATION PRINCIPLES MAIN STEPS OF THE WATER-STEAM CYCLE PROPERTIES OF STEAM GENERATION Condensation (Co...

MarEngg MIDTERM REVIEWER REPORT 1: BOILER OPERATION PRINCIPLES MAIN STEPS OF THE WATER-STEAM CYCLE PROPERTIES OF STEAM GENERATION Condensation (Condenser) - After passing through the turbine, the Water Heating low-pressure steam enters a condenser. Here, - Water is heated in a boiler using various energy the steam is cooled and condenses back into sources such as natural gas, coal, oil, or water by transferring its heat to a cooling electricity. medium, typically water or air. Steam Production - The condensed water is collected and returned - As the water temperature rises, it eventually to the cycle. reaches its boiling point and transforms into Pressurization (Pump) steam. This phase change absorbs a significant - The condensed water is then pressurized by a amount of heat, known as latent heat. feedwater pump to raise its pressure. This step Steam Collection ensures that the water can be reused in the - The steam produced in the boiler is collected in boiler. a steam drum or header. Here, the steam can be - The water is then pumped back into the boiler, separated from any remaining water. completing the cycle. Steam Distribution Heat Transfer - The generated steam is then directed through - occurs between states of matter whenever a pipes to where it will be used, such as in temperature difference exists and heat transfer turbines for electricity generation, heating occurs only in the direction of decreasing systems, or industrial processes. temperature, meaning from a hot object to a cold Condensation object. - After performing its work (like turning a turbine), Conduction the steam condenses back into water. This is - the process by which thermal energy is often done in a condenser, where the steam transferred from a region of higher temperature releases its latent heat to a cooling medium. to a region of lower temperature within a Water Return material or between materials in direct physical - The condensed water, now in liquid form, is contact. returned to the boiler to be reheated and turned Convection back into steam, completing the cycle. - The movement of fluid molecules from higher temperature regions to lower temperature Ideal Rankine Cycle regions. - Also known as the water-steam cycle, is a Radiation thermodynamic process widely used in power - the process in which thermal energy is generation, particularly in steam turbines found transferred through electromagnetic waves, in coal, natural gas, nuclear, and solar thermal typically in the infrared spectrum. Unlike power plants. conduction and convection, radiation does not - The cycle describes how heat energy is require a medium, meaning it can occur in a converted into mechanical energy (and vacuum. eventually electricity) using water as the working fluid  REPORT 2: oxygen from the air. As a result of this BOILER FUELS & COMBUSTION combination, heat is produced. Combustion - the rapid oxidation of a fuel whereby large quantities of heat are produced. Boiler Fuels - refer to the various types of fuels that can be CONDITIONS FOR COMPLETE COMBUSTION: burned in a boiler to generate heat or steam for industrial processes, heating, or electricity 1. Enough Air generation. - Enough air must be supplied to the boiler Combustion to provide sufficient oxygen to combine - a chemical reaction that occurs when a fuel the fuel. reacts with oxygen, producing heat and often 2. Turbulence light. - the thorough mixing of fuel and air so that each particle of fuel can come in TYPES OF FUELS contact with the necessary oxygen. 3. Temperature 1. Coal - A solid fossil fuel used in large boilers, - The temperature in the boiler must be known for high energy output but significant high enough to ignite the fuel as it enters. emissions. 4. Time 2. Heavy Fuel Oil (HFO) - Thick oil from crude, - The boiler must be large enough to allow used in industrial boilers; high emissions, sufficient time for the combustion to be requires pre-heating. completed. 3. Light Fuel Oil (LFO) - Lighter oil like diesel, easier to handle, used in smaller boilers. Air-Fuel Ratio 4. Natural Gas - A clean, efficient fossil fuel, widely - defines the amount of air needed to burn a used in boilers for its low emissions. specific fuel. The amount of air required will vary 5. Liquefied Petroleum Gas (LPG) - Primarily depending on the type of fuel. consisting of propane and butane, is commonly used as fuel in areas without access to natural HFO: 14.5:1 gas pipelines for heating, cooking, and energy Gasoline: 14.7:1 needs. Natural Gas: 10:1 6. Biomass - A mixture of propane and butane LPG: 15.6-15.8:1 gases, stored in liquid form. It is a cleaner Coal: 7-8:1 alternative to traditional fuels and is used in specialized ships. METHODS TO IMPROVE 7. Biodiesel - A renewable fuel derived from COMBUSTION EFFICIENCY vegetable oils or animal fats, used in some marine engines. It is more environmentally 1. Feedwater Temperature friendly and produces fewer emissions. - The temperature of the feed water must 8. Hydrogen - An experimental fuel used in some be kept within the range of 80 to 85 marine fuel cells. It burns cleanly, producing only degrees Celsius, as maintaining this water vapor as an emission, and is being temperature is important for achieving explored for zero-emission shipping. higher operational efficiency of the boiler. 2. Structural Importance Combustion Theory - The outer structure, or shell, of the boiler - In the process of combustion, the main is essential for maintaining the combustible elements of the fuel, carbon, temperature of the flue gas, which hydrogen, and sulphur, combine chemically with promotes greater heat exchange, while also containing the internal pressure.  REPORT 3: BOILER WATER SYSTEM 3. Air or Steam Supply to the Burner - A proper balance of air and fuel ensures Feedwater System complete combustion. To achieve proper - are essential components in boiler operations, combustion in a fuel oil-operated marine designed to supply water to the boiler for steam boiler equipped with a register burner, it generation. The primary purpose of these is essential to maintain an air/steam systems is to ensure a continuous and adequate percentage of 15–20%. supply of water, which is crucial for maintaining 4. Boiler Loading the boiler’s efficiency and operational safety. - The optimal operating range for achieving the best efficiency is around MAIN COMPONENTS two-thirds of the boiler's full load capacity. This ensures that combustion is Feedwater Pumps more complete, reducing fuel - These pumps are responsible for moving water consumption and maximizing thermal from the storage tank to the boiler. They must be efficiency. reliable and capable of handling the required 5. BLow Down Control pressure and flow rates. - Regular blowdowns help remove Deaerator impurities that accumulate in the boiler - remove dissolved gasses, primarily oxygen and water due to evaporation and carbon dioxide, from the feedwater to prevent contamination. This process also helps corrosion. control the chloride levels to reduce the Storage Tanks risk of damage to boiler components. - These tanks store treated water before it is fed 6. Soot Deposits into the boiler, ensuring a steady supply and - The economizer tubes and boilers must allowing for any necessary adjustments in water be cleaned, especially since oil-fired quality. boilers are prone to soot deposits in the tubes. These deposits can act as IMPORTANCE OF insulators, diminishing the effective heat FEEDWATER SYSTEM transfer area and reducing overall efficiency. 1. Preventing Scaling 2. Avoiding Corrosion 3. Maintaining Efficiency 4. Prolonged Equipment Life TYPES OF FEEDWATER TREATMENT 1. Mechanical Treatment Filtration - Removes suspended solids and particulates from the water. Deaeration - Eliminates dissolved gasses to prevent corrosion. 2. Chemical Treatment Softening - Uses ion exchange to remove hardness-causing minerals like calcium and magnesium.  Chemical Addition - Involves adding REPORT 4: EFFICIENCY AND chemicals to control pH, prevent scaling, PERFORMANCE and inhibit corrosion. Water Impurities Boiler Efficiency - Substances dissolved or suspended in water, - the combined performance of different parts of a such as gases, minerals, organic materials, and boiler. particles. Direct Efficiency - can cause problems including scaling, fouling, - This method measures efficiency simply by and corrosion in boiler feedwater systems, which dividing the energy output (steam produced) by can reduce equipment lifespan and efficiency the energy input (fuel used), and multiplying by 100. CLASSIFICATIONS Indirect Efficiency OF IMPURITIES - calculated by measuring each type of loss, such as heat escaping through the stack or blowdown Dissolved Gasses losses. - Oxygen, Carbon dioxide, and Hydrogen Combustion Efficiency sulfide, which are naturally present in - the amount of unburnt fuel left in the exhaust. water - The level of extra oxygen in the exhaust. Suspended Solids Thermal Efficiency - Sediment or organic matter, which comes - how well the boiler transfers heat from the fire to along with the makeup water the water. Dissolved Solids - This includes impurities like hardness Energy losses in boilers significantly affect efficiency and sulfate carbonates. and operational costs in industrial settings. Key types of losses include: EFFECTS OF WATER IMPURITIES 1. Stack Losses: Heat lost through exhaust gases, which can be reduced with heat recovery Corrosion systems. - the breakdown of metal surfaces due to 2. Radiation Losses: Heat escaping from the chemical interactions with water contaminants. boiler's surface to the environment. Scale Formation 3. Convection Losses: Heat loss due to air - It occurs when dissolved minerals separate from movement around the boiler. the boiler water and gather on surfaces used for 4. Blowdown Losses: Heat lost during the heat transfer. periodic removal of water to manage impurities. Overheating - An excessive rise in temperature of boiler Feedwater Economizer components beyond their designed limits. - appropriate when insufficient heat transfer Reduced Efficiency surface exists within the boiler to remove - The decline in the boiler's operational combustion heat. performance. - reduces steam boiler fuel requirements by transferring heat from the flue gas to incoming Boiler Blowdown feedwater. - the process of removing impurities from a boiler Air Preheaters to ensure it operates safely and efficiently. - mainly used for exhaust-to-air heat recovery - this system is particularly useful where cross contamination in the process must be prevented.  REPORT 5: BOILER SAFETY SYSTEMS Boiler Safety System - Are critical for ensuring the operation of marine boilers. Safety Valves and Pressure Relief System - Designed to automatically release pressure from the boiler when it exceeds a predetermined limit. 1. Spring-Loaded Safety Valves - Most common type and designed to open at a predetermined pressure and close when the pressure drops at a safe level. 2. Pilot-Operated Relief Valves - Valves used in high pressure applications and provide more precise control. Low Water Cutoff Devices - Devices that prevent boiler damage due to low water levels. 1. Float Type - Utilizes a mechanical float to detect the water level. 2. Electronic Type - Uses electronic sensors to monitor the water level. Flame Detection and Control Systems - Like a safety guard that makes sure the fire inside the boiler is burning safely and efficiently. Flame Detectors - Used in multi burner utility and large industrial boilers to detect the presence and absence of flame. Boiler Control System - A set of devices and software that monitors and regulates the operation of a boiler.