[Q&A Question 202] 2018.07.27
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【Q&A Question 202】July 27, 2018: Briefly explain why ash accumulates in heating furnaces. What are the hazards of ash accumulation? Reasons: The ash in heating furnaces mainly comes from the ash content in fuel oil (which is non-combustible); it also originates from sulfur in the fuel, as this sulfur is not oxidized during combustion. Additionally, solid particles produced by incomplete combustion contribute to ash accumulation. Harm: ① It increases the heat transfer resistance, resulting in an increase in the exhaust gas temperature ； ② The resistance to flue gas flow increases, leading to an increase in furnace pressure and the leakage of hot flue gas ； ③ It exacerbated dew point corrosion. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) Correct: 3 wealth, Incorrect: 1 wealth ； Mass posting of posts – rated based on the lowest score ； Replies that are unrelated to the answer are considered spam and will be deleted immediately. For management purposes, if you need to view content from a few days ago, please go to https://bbs.hcbbs.com/home.php?mod=space&uid=3862647&do=thread&view=me&from=space through the summary post below
Ash deposition occurs due to temperatures below the melting point of the ash, and it can be divided into high-temperature ash deposition and low-temperature ash deposition. The main hazards are: 1. Reduced thermal efficiency of the boiler, as the thermal resistance of ash deposits is 40 times that of steel, resulting in a significant drop in the boiler’s thermal efficiency ； 2. The exhaust gas temperature rises, increasing heat loss ； 3. Due to the reduced heat transfer efficiency of the heating surfaces, the boiler’s output is insufficient ； 4. A decrease in thermal efficiency and excessively high exhaust temperatures can also cause damage to the tail gas flow channels ； 5. Since the heated surfaces are unable to transfer heat effectively to the medium inside the boiler, the furnace temperature rises further, and this increase in furnace temperature exacerbates coking in the furnace arch.
Reasons for dust accumulation: 1. The fuel contains ash； 2. Local soot blower malfunction; unable to perform soot blowing ； 3. Severe air leakage, with low local smoke flow velocity ； Harm of ash accumulation in heating furnaces: 1. The thermal efficiency of the heating furnace decreases, as the thermal resistance of ash deposits is 40 times that of steel, resulting in a significant drop in the furnace’s thermal efficiency ； 2. The exhaust gas temperature rises, increasing heat loss ； 3. Due to the reduced heat transfer efficiency of the heated surfaces, the heating furnace lacks sufficient output ； 4. A decrease in thermal efficiency and excessively high exhaust temperatures can also cause damage to the tail gas flow channels ； 5. Since the heated surfaces are unable to transfer heat effectively to the medium inside the boiler, the furnace temperature rises further, and this increase in furnace temperature exacerbates coking in the furnace arch.
The ash accumulation in heating furnaces mainly comes from the ash content in the fuel oil (which is non-combustible); secondly, it comes from sulfur in the fuel, as this sulfur is not oxidized during combustion. Additionally, it arises from solid particles produced during incomplete combustion. Hazards: ① It increases the heat transfer resistance, leading to an increase in the exhaust gas temperature; ② It raises the flow resistance of the flue gases, causing the furnace pressure to rise and high-temperature flue gases to leak; ③ It exacerbates dew point corrosion.
Soot is the non-combustible residue left after the combustion of fuel oil, consisting of solid metal salts such as Na, K, V, Mg, and other impurities, as well as particles of combustible components that remain when combustion is incomplete. It is pointed out that the level of fuel ash content, the quality of burner atomization, the temperature of the combustion air, and the technical skill of the operators are all major factors affecting the amount of slag formation. The dust accumulation patterns on the outer wall of the radiant chamber tubes and those of the convection tube walls were analyzed. It is pointed out that dust accumulation outside the tubes increases the thermal resistance, affecting heat transfer and resulting in a decrease in thermal efficiency; it reduces the flow area of the flue gases, increasing their flow velocity and thus the flow resistance, which in turn affects the normal combustion in the burner; it also exacerbates dew point corrosion, shortening the service life of the heating furnace
Reasons for dust accumulation: 1. The fuel contains ash； 2. Local soot blower malfunction; unable to perform soot blowing ； 3. Severe air leakage, with low local smoke flow velocity ； ? Hazards of ash accumulation in heating furnaces: 1. The thermal efficiency of the heating furnace decreases, as the thermal resistance of ash is 40 times that of steel, resulting in a significant drop in the furnace’s thermal efficiency ； 2. The exhaust gas temperature rises, increasing heat loss ； 3. Due to the reduced heat transfer efficiency of the heated surfaces, the heating furnace lacks sufficient output ； 4. A decrease in thermal efficiency and excessively high exhaust temperatures can also cause damage to the tail gas flow channels ； 5. Since the heated surfaces are unable to transfer heat effectively to the medium inside the boiler, the furnace temperature rises further, and this increase in furnace temperature exacerbates coking in the furnace arch.
Reason: The ash accumulation in the heating furnace mainly comes from the ash content in the fuel oil (which is non-combustible); it also originates from sulfur in the fuel, as this sulfur is not oxidized during combustion. In addition, solid particles produced during incomplete combustion contribute to ash accumulation as well. Harm: ① It increases the heat transfer resistance, resulting in an increase in the exhaust gas temperature ； ② The resistance to flue gas flow increases, leading to an increase in furnace pressure and the leakage of hot flue gas ； ③ It exacerbated dew point corrosion
The ash accumulation in the heating furnace mainly comes from the ash content in the fuel oil (ash is non-combustible). Harm: ① It increases the heat transfer resistance, leading to an increase in the exhaust gas temperature; ② It raises the flow resistance of the flue gases.
The ash accumulation in heating furnaces mainly comes from the ash content in the fuel oil (which is non-combustible); it also originates from sulfur in the fuel, as this sulfur is not oxidized during combustion. In addition, solid particles produced as a result of incomplete combustion contribute to ash accumulation. Harm: ① It increases the heat transfer resistance, resulting in an increase in the exhaust gas temperature ； ② The resistance to flue gas flow increases, leading to an increase in furnace pressure and the leakage of hot flue gas ； ③ It exacerbated dew point corrosion.
Dust accumulation refers to metal oxides and particles that adhere to the surface of furnace tubes; it significantly reduces the thermal efficiency of the heating furnace
Reason: The ash accumulation in the heating furnace mainly comes from the ash content in the fuel oil (which is non-combustible); secondly, it comes from the sulfur in the fuel, as this sulfur is not oxidized during combustion. Additionally, it comes from solid particles generated during incomplete combustion. Harm: ① It increases the heat transfer resistance, resulting in an increase in the exhaust gas temperature ； ② The resistance to flue gas flow increases, leading to an increase in furnace pressure and the leakage of hot flue gas ； ③ It exacerbated dew point corrosion.