低阶煤滚筒干燥煤尘抑爆技术研究

发布时间：2019-05-16 11:24

【摘要】：我国低阶煤储量丰富,但由于低阶煤变质程度低、含水率较高,加之其易自燃、难运储等原因,致使其工业利用价值受到很大局限,所以,基于低阶煤的特性,采用物理方法对其进行干燥提质,实现其发热量的较大幅度提高,从而提升了煤炭资源利用率。在现阶段煤炭物理干燥提质技术中,滚筒干燥技术已经较为成熟,并广泛应用于高阶煤的物理干燥提质。但对于低阶煤,由于滚筒干燥过程中煤尘产生量大,当煤尘达到爆炸极限浓度、引风装置将燃烧器内高温烟气掺杂引火火源引入滚筒、滚筒内热烟气中氧气含量充足三个条件同时具备时,就必然发生煤尘的爆燃爆炸。虽经实验室以及工程实践数次试验,但均不能实现大幅度降低煤尘以及绝对消除高温烟气中的火星,所以,研究有效控制滚筒内氧气浓度在安全范围之内,是实现系统煤尘抑爆的关键。依据煤尘灾害发生机理,在分析研究低阶煤理化性质、滚筒干燥提质系统工艺及其装配基础上,利用流体力学软件Fluent及相关理论,对滚筒干燥机内不同入口烟气温度下滚筒干燥机内氧气浓度及降水率的动态变化进行模拟研究,获得了高温烟气温度、降水率与滚筒内氧含量之间的关系及其变化规律;研发了基于负氧热烟气可控循环利用系统。工程实践中,基于干燥物料的特性,附以滚筒干燥机内部结构的调整以及系统运行参数的优化,可实现有效控制滚筒内氧气浓度、抑制煤尘的爆炸。
[Abstract]:China is rich in low-rank coal reserves, but because of its low metamorphism, high water content, easy spontaneous combustion, difficult to transport and storage and other reasons, its industrial utilization value is greatly limited, so, based on the characteristics of low-rank coal, The physical method is used to dry and improve the quality, so that the calorific value of the coal resource can be greatly improved, and the utilization rate of coal resources can be improved. At present, the drum drying technology has been more mature in the physical drying and quality improvement technology of coal, and is widely used in the physical drying of high-grade coal. However, for low-order coal, because of the large amount of coal dust produced in the drying process of the drum, when the coal dust reaches the explosion limit concentration, the air entraining device introduces the high temperature flue gas doping ignition source in the burner into the drum. When the oxygen content in the hot flue gas is sufficient at the same time, the deflagration explosion of coal dust will inevitably occur. Although it has been tested several times in laboratory and engineering practice, it can not greatly reduce coal dust and absolutely eliminate Mars in high temperature flue gas. Therefore, the effective control of oxygen concentration in drum is within a safe range. It is the key to realize the explosion suppression of coal dust in the system. According to the occurrence mechanism of coal dust disaster, on the basis of analyzing and studying the physical and chemical properties of low rank coal, the technology of drum drying and quality improvement system and its assembly, the hydrodynamics software Fluent and related theories are used. The dynamic changes of oxygen concentration and water reduction rate in drum dryer at different inlet flue gas temperatures were simulated and studied, and the relationship between high temperature flue gas temperature, water reduction rate and oxygen content in drum was obtained. A controllable recycling system based on negative oxygen heat flue gas is developed. In engineering practice, based on the characteristics of dry materials, with the adjustment of the internal structure of the drum dryer and the optimization of the operating parameters of the system, the oxygen concentration in the drum can be effectively controlled and the explosion of coal dust can be suppressed.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD714.5

【参考文献】