【Weekly Topic】20150706 What are the main aspects of heat loss in boilers? (Participation rewards available)

1. The sealing performance of the boiler. 2. Oxygen content in flue gas (blower flow rate) 3. Flue gas temperature (damper opening) 4. Fuel combustion condition (combustion efficiency) 5. Combustion speed (coal layer thickness, nozzle atomization quality) 6. Heat dissipation from the boiler walls (heat loss) 7. Heat exchange efficiency of boiler tubes and preheaters.

Heat loss due to smoke exhaust, heat loss from incomplete chemical combustion, heat loss through heat dissipation, physical heat loss from slag, leakage losses, and heat loss from incomplete mechanical combustion.

(1) Heat loss due to flue gas: The flue gas emitted by the boiler carries some heat into the atmosphere, resulting in heat loss due to flue gas; this is the largest among all types of heat losses in a boiler. The main factors affecting the heat loss due to exhaust smoke are the exhaust smoke temperature and the volume of exhaust smoke. The higher the exhaust smoke temperature and the greater the volume of exhaust smoke, the greater the heat loss due to exhaust smoke. The level of flue gas temperature mainly depends on the number of heated surfaces and the operating conditions ； The amount of smoke exhaust depends on the excess air coefficient as well as the air leakage in the furnace and flue. 　(2) Heat loss due to incomplete combustion of gases: This refers to the heat loss that occurs when some of the combustible gases in the exhaust fumes are not burned and are thus discharged along with the fumes. The main factors affecting the heat loss due to incomplete combustion of gases are the excess air coefficient and the furnace structure. An excessively low excess air coefficient leads to uneven mixing of air and fuel, facilitating the formation of combustible gases such as carbon monoxide ； An excessively high excess air coefficient will lower the furnace temperature, making it difficult for combustible gases to ignite and burn. If the furnace volume is too small, the combustible gas does not have enough time to burn inside the furnace before entering the flue, resulting in incomplete combustion and heat loss. 　 　(3) Heat loss due to incomplete combustion of solids: The heat loss resulting from a portion of the solid combustibles in the fuel that does not participate in combustion or remains unburned and is discharged outside the furnace. It consists of three components: fly ash loss, slag loss, and coal leakage loss, and it represents a major heat loss in coal-fired boilers. The main factors affecting the heat loss due to incomplete combustion of solids include the type of fuel, combustion method, furnace structure, and operating conditions. 　 　(4) Heat loss due to heat dissipation: The thermal loss caused by the furnace walls, frames, pipes, and door openings dissipating heat into the surrounding environment. The magnitude of heat loss depends mainly on factors such as the surface area of the boiler furnace wall, its insulation properties and thickness, as well as the temperature and flow velocity of the external air. 　(5) Physical heat loss due to ash: The heat loss resulting from the high-temperature ash discharged from the boiler carrying away a portion of the heat. The magnitude of this heat loss is related to factors such as the ash content in the fuel, the calorific value of the fuel, and the form of the slag.

1. Heat loss due to flue gas temperature, 2. Incomplete combustion of gases, 3. Incomplete combustion of solids, 4. Natural heat dissipation loss, 5. Combustion losses within the furnace, 6. Losses due to the discharge of hot slag.

1. Heat loss due to flue gas; 2. Heat loss due to incomplete chemical combustion; 3. Heat loss due to incomplete mechanical combustion; 4. Heat loss due to incomplete solid combustion; 5. Heat loss due to heat dissipation; 6. Physical heat loss due to ash and slag

1. Heat loss due to smoke exhaust. 2 Heat loss due to incomplete chemical combustion. 3. Heat loss due to incomplete combustion of the engines. 4 Heat loss due to incomplete combustion of solids. 5 Heat loss. 6 Physical heat loss of ash.

1. The flue gas emitted by the boiler carries some heat into the atmosphere, resulting in flue gas heat loss； 2. Heat loss caused by a portion of the combustible gases in the exhaust fumes being discharged along with the fumes without undergoing combustion and releasing heat ； 3. Heat loss caused by the discharge from the furnace of certain solid combustibles in the fuel that have not participated in combustion or have not been completely burned ； 4. Heat loss caused by the furnace walls, frameworks, pipes, and door openings dissipating heat to the surrounding environment ； 5. Heat loss caused by the high-temperature ash and slag discharged from the boiler taking away some of the heat.

The thermal losses of a boiler mainly include the following aspects: flue gas heat loss q2, chemical incomplete combustion heat loss q3, mechanical incomplete combustion heat loss q4, heat dissipation loss q5, and physical heat loss of slag q6

1. Heat loss due to smoke exhaust. 2. Heat loss due to incomplete chemical combustion. 3. Heat loss due to incomplete combustion in the machine. 4. Heat loss due to incomplete combustion of solids. 5. Heat dissipation (leakage) losses. 6. Physical and thermal losses of ash. .

Boiler heat loss: 1. Physical heat carried away by ash and slag, as well as the loss of unburned carbon in the ash and slag (not applicable to oil or gas boilers)； 2. Heat loss due to smoke exhaust ； 3. Heat loss due to incomplete chemical combustion ； 4. Heat dissipation loss ； 5. Heat loss due to waste gas emission ； 6. Heat loss due to incomplete combustion in the machinery (coal leakage through the grate). I can’t remember the exact percentage of efficiency! Total efficiency loss: 25–15% for coal-fired boilers, 12–6% for oil and gas-fired boilers