Knowledge Management System of Institue of Mechanics, CAS
| 气脉冲除灰技术燃烧和除灰过程研究 | |
| 樊未军 | |
| Thesis Advisor | 吴承康 ; 孙文超 |
| 1999 | |
| Degree Grantor | 中国科学院研究生院 |
| Place of Conferral | 北京 |
| Subtype | 博士 |
| Degree Discipline | 流体力学 |
| Keyword | 气脉冲 除灰器 锅炉积灰 火焰传播 Gas Pulse Ash Remover Boiler Deposits Propagation Of Flame |
| Other Abstract | 中国电站锅炉燃用大量的未经洗选的劣质煤，导致严重的锅炉积灰问题，尤其是125-600MWe的大型锅炉的回转式空气预热器堵灰更加严重。积灰不仅使锅炉热效率下降，而且堵塞烟气流道，影响了锅炉的正常运行。已有的各种除灰器都有较大的局限性。中国科学院力学研究所燃烧研究实验室根据我国国情开发出了燃烧气脉冲除灰技术，并在30多台大型电站锅炉应用取得了很好的效果。为了理解气脉冲除灰的工作过程，掌握运行规律，解释应用中出现的问题，以提高技术水平和开发新产品，尚需对气脉冲除灰的燃烧和除灰过程做更深入的研究。本论文工作针对燃烧气脉冲除灰技术在实际使用中提出的问题，开展了实验室研究。主要研究了乙炔、水煤气、液化石油气和甲烷四种燃料在气脉冲实验装置中的火焰传播情况和压力波形。研究了混合比、阻塞比和出口截面比对火焰速度和压力峰值的影响。在现有点火条件下找到了在静止混合气体中四种燃料的贫点火极限和乙炔在有一定流速时的贫点火极限；比较了燃烧室内乙炔空气混合物静止时和有一定流速时的爆炸压力峰值。初步搞清了各种因素对火焰速度和压力波形的影响，实验结果对实际应用有指导作用。为了理解火焰传播和压力波形之间的关系，用燃烧室内压力均匀的简化模型，计算了压力波形并且与实验结果进行了对照，由此推算了湍流燃烧速度并探讨了各种因素对它的影响。用考虑了管内有压力波传播的一维简化模型，计算了火焰传播过程中燃烧室两端的压力波形和火焰面前后的气流速度，以及不同时刻的燃烧室内气体流速分布。估算了气流剪切力的量级，进行了模拟积灰的气脉冲对比实验，测量了同一气脉冲条件下两种厚薄不同板的振动加速度值及其随时间和空间的衰减情况。还得到了压力在空间的衰减变化情况。定性地研究了积灰脱落机理，初步认为：对于粘结灰只有振动才有效，气流的剪切不能除去粘结灰。; Chinese power plants burn a large amount of high-ash coal without washing, so the fouling problems are often serious, especially in the rear portion of the flue gas passage. For instance, the rotary air preheaters are often fouled up so badly that the furnace has to be stopped for mechanical cleaning of the gas passages. The ash deposits cause lowering of heat transfer capacity and rise in flow resistance, resulting in reduction of output and boiler efficiency. How to remove the ash deposits for reliable and economical operation is an important and long-standing problem. At the Combustion Laboratory, Institute of Mechanics, Chinese Academy of Sciences, the highly effective Gas-Explosion Ash Remover(GEAR) has been developed. More than thirty sets of the apparatus have been applied to the air preheaters of 125-600MWe power plants in China with good results. But more profound studies on the process of combustion and ash removal are needed to comprehend the working mechanism of the apparatus, solve problems arising in industrial applications, improve performance and reliability and develop new products. Some technical problems brought up during practical applications were studied in this thesis. Propagation of flame and pulse shape of pressure in the combustion chamber with four kinds of fuel (acetylene, water gas, liquefied petroleum gas and methane) were measured in the experimental apparatus. Flame speeds and peak pressures were compared at various fuel/air equivalence ratios. Effects of blockage ratios and outlet area ratios on flame velocity and peak pressure were investigated. Different lean ignition limits of the four fuels were determined under the test condition with flowing or non-flowing fuel/air mixtures. The experimental results are useful in providing some guidance for industrial application. To understand the relationship between flame propagation and pressure rise, the pressure development was calculated from the measured flame position at various times with a much-simplified model assuming that the flame front was plane and the pressure uniform at any given moment. The calculated pressure shape was compared with the experimental. By this model, turbulent burning velocity S_T was calculated and various factors affecting S_T were investigated. Pressure pulse shapes at closed end and outlet end in the combustion tube as well as flow speeds behind and before the flame front, flow speed distribution at different times were calculated with a one-dimensional model considering pressure wave propagation. Magnitude of shearing stress on the ash deposit exerted by the gas jet was estimated. Various "simulated ash deposits" were cleaned under different conditions by the action of the jet. The overpressure caused by the jet in the atmosphere at different positions and vibrant acceleration of plates with different thickness and its attenuation distance were measured. It is concluded that stuck ash is removed mainly by vibration of the plate rather than by the shearing stress of gas flow. |
| Call Number | 29866 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://dspace.imech.ac.cn/handle/311007/22990 |
| Collection | 力学所知识产出(1956-2008) |
| Recommended Citation GB/T 7714 | 樊未军. 气脉冲除灰技术燃烧和除灰过程研究[D]. 北京. 中国科学院研究生院,1999. |
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| File Name/Size | DocType | Version | Access | License | ||
| 气脉冲除灰技术燃烧和除灰过程研究.pdf（20087KB） | 开放获取 | -- | Application Full Text | |||
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