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I. Term Explanations (related to boilers) 1. Boiler rated evaporation capacity: The amount of steam that a steam boiler is capable of producing under rated steam parameters, rated feedwater temperature, using the designed fuel, and while maintaining efficiency. 2. Maximum continuous evaporation capacity of the boiler: The maximum amount of vapor that a steam boiler can produce when it operates continuously for an extended period under rated steam parameters, rated feedwater temperature, and using the designed fuel. 3. Rated steam parameters of the boiler: Rated steam pressure and rated steam temperature at the superheater outlet. 4. Boiler accident rate: Boiler accident rate = ×100% 5. Boiler availability: Boiler availability = ×100% 6. Boiler thermal efficiency: The percentage of the effective heat utilized by the boiler per hour, out of the total heat input to the boiler. 7. Boiler steel consumption rate: The tons of steel used per unit of evaporation capacity of the boiler. 8. Continuous operating hours: The number of hours the system operates between two maintenance sessions. II. Term Explanations (related to fuel) 1. Calorific value: The heat released when a unit mass or volume of fuel burns completely. 2. Higher heating value: The total amount of heat released when a unit amount of fuel is completely burned, and all the water vapor in the combustion products condenses into water, is known as the higher heating value of the fuel. 3. Lower calorific value: the total heat released when a unit amount of fuel is completely burned, with all water vapor in the combustion products remaining in gaseous form. 4. Composition on an equivalent basis: refers to the composition of the fuel in terms of its lower heating value per 4190 kJ/kg on a received basis. 5. Standard coal: Coal with a specified lower heating value on a received basis of Qarnet=29270 kJ/kg. 6. Volatiles of coal: The gases that are released as a result of the decomposition of the organic matter in coal when the coal sample, after having had its moisture removed, is heated under specified conditions. 7. Flash point of oil: The lowest temperature at which, when a liquid fuel is heated under certain conditions, the mixture of vapor on the surface of the liquid and air catches fire briefly upon contact with an open flame before going out immediately. 8. Ash fusion behavior: The characteristic changes in the physical states of ash such as deformation, softening, and flowage as the heating temperature changes under specified conditions. III. Term Explanations (related to combustion) 1. Combustion: A chemical reaction process in which the combustible components in a fuel react with oxygen under high temperatures, resulting in intense light emission and heat release. 2. Complete combustion: Combustion in which the combustion products no longer contain any combustible materials. 3. Incomplete combustion: A type of combustion in which combustible substances are still present in the combustion products. 4. Theoretical air volume: The amount of air required for complete combustion of 1 kg of fuel on a received basis, with no residual oxygen present. 5. Excess air coefficient 6. Air leakage coefficient 7. Theoretical flue gas volume: The amount of flue gas generated when air is supplied based on the theoretical air volume, for the complete combustion of 1 kg of fuel. 8. Flue gas enthalpy: The heat required to heat the flue gas generated by 1 kg of solid or liquid fuel from 0°C to θ°C at constant pressure. 9. Flue gas composition: The percentage of the partial volume of a certain gas in the flue gas relative to the volume of dry flue gas. IV. Term Explanations (related to thermal efficiency and heat loss) 1. Boiler thermal balance: The state of equilibrium between the heat input to the boiler and the heat output by the boiler under stable operating conditions. 2. Optimal excess air coefficient: Heat loss caused by the sensible heat in the flue gases discharged from the boiler. : Losses resulting from the failure of solid combustibles in fly ash, slag, and coal leakage to release their heat of combustion. : The loss resulting from residual combustible gases in the boiler exhaust not releasing their heat of combustion. 6. Positive balance thermal efficiency: The percentage of the heat effectively utilized by the boiler, relative to the heat input from the fuel consumed per unit of time. 7. Reverse balance thermal efficiency: It is the efficiency calculated by taking the input heat as 100% and then subtracting various heat losses from this percentage. 8. Effective heat utilization of the boiler: The total amount of heat absorbed by the working fluid in the boiler per unit of time. 9. Boiler fuel consumption: The amount of fuel consumed by the boiler per unit of time. 10. Calculated fuel consumption of the boiler: The fuel consumption after deducting the heat loss due to incomplete combustion of solids. V. Term Explanations (related to coal powder) 1. Coal powder fineness: The percentage of the mass a of coal powder remaining on the sieve after it has been screened using a special sieve, relative to the total mass of the coal powder before screening. The definition formula is R=a/（a+b）×100%. 2. The economic fineness of coal powder; 3. The grindability coefficient of coal: the ratio of the energy consumed to grind coal of standard quality and test coal to the same fineness from the same particle size, in their air-dried state. 4. Coal wear index: Under certain experimental conditions, it is the ratio of the amount of wear caused per minute by a particular type of coal on pure iron to the amount of wear caused per minute by standard coal under the same conditions. 5. Steel ball filling coefficient: The ratio of the volume occupied by the steel balls loaded in the ball mill to the volume of the mill cylinder. 6. Optimal coal grinding ventilation volume. 7. Direct-fired coal grinding system: A coal grinding system in which the coal powder ground by the grinder is directly blown entirely into the furnace for combustion; the amount of coal powder produced in this system is equal to the amount required by the boiler, and it changes as the boiler load varies. 8. Silo-type coal grinding system: The coal powder ground by the coal grinder is first stored in a coal powder silo, and then, depending on the boiler’s load requirements, it is sent from the silo to the furnace for combustion through a coal feeder – this is the coal grinding system. 9. Primary air: Hot air that carries coal powder into the furnace. 10. Secondary air: Pure hot air that enters the furnace through the burner to supply the oxygen required for fuel combustion. 11. Third air: In the hot air powder feeding system of intermediate storage-type coal grinding systems, the coal grinding exhaust gas carrying fine powder is fed into the furnace for combustion through specialized nozzles; this is known as third air. 12. Coal grinding output: The amount of raw coal that can be ground by the coal grinder per unit of time, under the condition that a certain particle size of the raw coal and a specific fineness of the coal powder are maintained. 13. Drying capacity. VI. Term explanations (theoretical knowledge of combustion): 1. Power combustion zone: A combustion condition in which the combustion rate is primarily determined by the rate of chemical reactions (chemical conditions), with little relation to the diffusion rate. 2. Diffusion combustion zone: A combustion condition in which the combustion rate depends primarily on the oxygen diffusion conditions, with little relation to temperature. 3. Transitional combustion zone: A combustion condition in which the combustion rate depends both on the chemical reaction conditions and on the diffusion and mixing conditions. 4. Ignition heat: The heat absorbed to raise the temperature of the coal powder and primary air stream from their initial temperature before entering the furnace to the ignition temperature. 5. Jet rigidity: The ability of the jet to resist deflection. 6. Heat load per volume of the furnace chamber: The average amount of heat supplied per unit volume of the furnace chamber per hour. 7. Thermal load per cross-sectional area of the furnace: The average amount of heat fed into the furnace per unit cross-sectional area per hour. 8. Heat load on the furnace wall in the burner area: The average heat input to the furnace per hour, calculated on a per unit area basis of the furnace wall in the burner area. 9. Slagging: The phenomenon where sticky ash adheres to the furnace chamber or high-temperature heating surfaces. 10. Iron precipitation in the slag pool: In a liquid slag discharge furnace, the phenomenon in which coarse particles in the coal powder stream settle into the slag pool, thereby reducing the iron oxide in the slag to pure iron. 11. High-temperature corrosion: refers to the corrosion that occurs on the outer wall of tubes in high-temperature heating surfaces such as water wall and superheaters, under the influence of high-temperature flue gas. 12. Low-temperature corrosion: Low-temperature corrosion is sulfuric acid corrosion that occurs on the heat-exchanging surfaces at the rear of the boiler (economizers, air preheaters). It is called low-temperature corrosion because the temperature of the flue gas and the tube walls in these rear heat-exchanging areas is low. Low-temperature corrosion often occurs on air preheaters, but it can also occur in economizer tubes. 13. Oxygen diffusion rate: The amount of oxygen transported per unit time across the boundary layer to the surface of a single carbon particle.