首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 125 毫秒
1.
内旋流流化床颗粒运动的研究   总被引:1,自引:0,他引:1  
内旋流流化床供风的速度较低、颗粒的流动属于稠密气固两相流,利用通常的测量手段研究内旋流流场,尤其是颗粒的速度场存在一定的困难,由于内旋流流化床是一种近似二维床,可以利用瞬态平面二维速度场测量技术(PV和DPIV)测量流化床某一断面的颗粒流场。对实验室原有的DPIV系统进行了改进,并用该系统初步研究了内旋流流化床颗粒运动的速度场。结果较好地描述了颗粒的二维流动。  相似文献   

2.
流化床中颗粒流化运动的直接数值模拟   总被引:16,自引:0,他引:16  
流化床燃煤锅炉对环境污染小的原因之一是是燃烧时间炉内加入脱硫剂,脱硫剂与某颗粒一起沸腾流化,相互充分接触,脱硫剂对燃烧过程中产生的硫化物进行反应吸收。由于喷入炉内的脱硫物质在粒径和密度上通常与煤颗粒不同,在流化区域上也存在差异。为了了解不同粒径和密度颗粒在流化床内的运动规律,达到高效、经济的脱硫效果,采用直接数值模拟方法,对粒径和密度呈正态分布的物料在流化床内的流化运动区域进行了研究,得到了相关的结论。  相似文献   

3.
循环流化床(CFB)锅炉炉内的燃烧及传热与炉内床料的状态密切相关,而炉内床料主要是由燃煤含有的矿物组分经过燃烧、爆裂和磨耗过程形成的。文中对6种煤样在固定床燃烧后,使用可视化显微仪,获取了灰颗粒的微观形貌特征,根据灰颗粒的机械强度和耐磨性能的不同,将灰颗粒定义为3类不同性质的灰。以此为基点,采用固定床燃烧后冷态振动筛分和流化床实验台热态流化后筛分的方法,研究了不同燃烧温度下升温速率对灰颗粒粒径变化的影响,以及不同燃烧温度下燃烧时间对灰颗粒粒径变化的影响,推演了不同煤样在燃烧过程中的演化特征。结果表明:3类灰颗粒在不同的燃烧温度和时间的演化过程存在明显的不同,从而为预测循环流化床中的床料粒径分布提供了理论依据。  相似文献   

4.
介绍了一种新型流化床锅炉-双循环流化床锅炉的主要技术特点,该锅炉实现流化床内和炉内空间的双循环燃烧,认为这是一种很有开发前景的新炉型和燃烧新技术。  相似文献   

5.
燃烧高水分低热值燃料的内旋流流化床燃烧技术研究   总被引:9,自引:2,他引:7  
内旋流型流化床炉利用非均匀布风产生高温气-固两相旋流,使燃料在炉内运动、相互碰撞、干燥、破碎、燃烧,并可通过改变布风控制燃料加热与挥发份析出速率、燃烧温度与热负荷,适合多种高水分劣质煤及城市垃圾的洁净燃烧,是一种高效低污染流化床燃烧技术。本文研究该型燃烧器床内空气运动、燃烧、传热及排放规律,发展新型清洁燃烧技术。  相似文献   

6.
以炉内直接脱硫的循环流化床锅炉为对象,分析了在循环流化床锅炉热效率计算中,其输入热量、燃烧所需空气量、燃烧生成烟气量及生成灰渣量与常规煤粉炉相比发生的变化。同时,文章也对循环流化床锅炉各项热损失进行了探讨。  相似文献   

7.
在电加热的小型流化床燃烧系统上,采用热烟气炉下点火方式研究了7个煤种的着火点,并分析了粒径、床温、挥发分、水分等因素对着火特性的影响.提出了煤颗粒在流化床内着火点测定的实验规范,并在TGA上测量着火点,与实际电厂锅炉投煤温度进行了比较.结果表明,在流化床实验台上测得的着火温度可以通过修正来表示实际锅炉上的投煤温度.  相似文献   

8.
一种改善循环流化床锅炉性能的方法   总被引:4,自引:1,他引:3  
金燕  郑洽余 《动力工程》1999,19(1):12-22
循环流化床锅炉出口几何结构对炉内气固两相流动特性和传热有特性很强烈的影响,称为循环流化床锅炉出口端头效应。该文通过试验分析了循环流化床锅炉出口端头效应的机理。结果表明,采用合理的出口几何结构,可以使其具有初级内分离器的功能,进而增强颗粒的内循环,延长颗粒在炉内的停留时间,增强炉内传热,全面改善循环流化床锅炉的性能。  相似文献   

9.
以HG-440/13.7-L.PM4型循环流化床锅炉为对象,开发了用于循环流化床锅炉燃烧系统仿真研究的软件。描述了以小室模型为基础的宽筛分固体颗粒的燃烧系统模型构建,包括固体颗粒和碳颗粒的质量平衡方程、氧气质量平衡方程、能量平衡方程、煤粒燃烧方程、炉内传热方程,简介了模型的求解方法和软件功能。  相似文献   

10.
采用锅炉排污水降压汽化作为蒸汽喷雾介质,在炉内燃烧空间形成切圆旋流,强化炉内燃烧,改善炉内气流动力分布状态。  相似文献   

11.
INTRODUCTIONThemethodhowtodealwiththedomesticandindustrialwasteswithoutfurthercontaminationisoneofthemostimportantenvironmentalissues.Fluidizedbedcombustor(FBC)hasadvantagesofhighcombustionefficiency)lowpollution,convenienceinpreprocessingbeforefedin...  相似文献   

12.
内旋流流化床燃烧系统设计研究   总被引:1,自引:0,他引:1       下载免费PDF全文
根据垃圾的热值和物理成分分析,结合流化床布风的冷态实验结果,对内旋流流化床燃烧系统进行了研究,设计出热态试验装置并成功地进行了生活垃圾焚烧试验。  相似文献   

13.
Fluidized bed combustion technology has been widely used as the new, flexible, multi-fuel boiler for waste combustion and energy recovery from low grade fuels. However, problems such as low thermal efficiency, high emissions, bed agglomeration etc. are still encountered in the operation of fluidized beds. Valuable experiences were gained from two case studies recently conducted regarding wastes combustion in industrial scale fluidized beds.In the first case, the performance of a fluidized bed combustor for energy recovery from oil sludge was evaluated during the commissioning trials. Apart from the sludge characterization and bed material analysis, the combustion efficiency, solid flow balance and on stack emission of CO, SOx and NOx were investigated, as well as the fluidization quality. Although the system was operated with good combustion efficiency (>99.9%), sulfur dioxide emission (>1000 ppm) was found to be substantially higher than the allowable discharge limit. It was recommended to increase the limestone feed rate in order to meet the SO2 emission standard, and subsequently, installation of a cyclone is suggested to remove the potentially significant increase in ash and fine particles.The second case study focused on the bed agglomeration observed in a fluidized bed incinerator where a burning blend of three wastes (i.e. carbon soot, biosludge and fuel oil) is involved. To understand the mechanisms and related chemistry, several analytical approaches are employed to identify the bed materials (fresh sand and degrader sand) and the clinkers formed from full scale incinerator tests. The formation of clinker is believed to follow the mechanism of partial melting and/or reactive liquid sintering. The effects of temperature and blending ratio are tested in a muffle furnace. Carbon soot is believed to be more susceptible than the other two fuels. Thermodynamic multi-phase multi-component equilibrium (TPCE) calculations predict that the main low melting point species are predominant under the oxidizing condition, suggesting that reducing conditions might be favorable to restrain bed agglomeration. This study provides valuable information for better understanding of the chemistry related to clinker formation; it also helps in developing methods for control and possible elimination of the bed agglomeration problem for the design fuels.  相似文献   

14.
Some aspects of fluidized bed combustion of paddy husk   总被引:1,自引:0,他引:1  
Some agricultural wastes—for example, bagasse, paddy husk, etc.—are frequently used as fuels, paddy husk appearing, in particular, to be quite suitable for fluidized bed combustion. The conventional method of combustion of paddy husk in grate-type furnaces is slow and inefficient.

This paper reports certain aspects of the fluidized bed combustion of paddy husk. Fluidized bed combustion was carried out by feeding husk in a bed of sand particles. The unexpanded bed height was 10 cm and the size of the sand particles, 351–420 μm. The superficial velocity of the ambient fluidization air through the bed ranged from 11·1 to 22·2 m/min.

A combustion intensity of about 530 kg/h/m2 of distributor area could be achieved. This is about 7·5 times higher than the maximum combustion intensity possible in a grate-type furnace per unit grate area. The efficiency of combustion, which ranged from 81 to 98 per cent was found to increase with the air flow rate. There was significant carry-over of inert sand particles from the bed under conditions of high air flow rate.

Combustion intensity increased as the bed height rose from 10 cm to 15 cm, but increased sand entrainment also occurred.  相似文献   


15.
The combustion performance of the boiler largely depends on the coal type. Lots of experimental research shows that different fuels have different combustion characteristics. It is obvious that fuel will change the whole operating performance of Circulating Fluidized Bed Combustion (CFBC). We know even in a pilot-scale running boiler, the measurement of some parameters is difficult and costly. Therefore, we developed the way of simulation to evaluate the combustion performance of Chinese coals in CFB. The simulation results show that, different coals will result in different coal particle diameter and comminution depending on their mineral component and the change will affect the distribution of ash in CFBC system. In a word, the computational results are in accordance with experimental results qualitatively but there are some differences quantitatively.  相似文献   

16.
The combustion performance of the boiler largely depends on the coal type. Lots of experimental research shows that different fuels have different combustion characteristics. It is obvious that fuel will change the whole operating performance of Circulating Fluidized Bed Combustion (CFBC). We know even in a pilot-scale running boiler, the measurement of some parameters is difficult and costly. Therefore, we developed the way of simulation to evaluate the combustion performance of Chinese coals in CFB. The simulation results show that, different coals will result in different coal particle diameter and comminution depending on their mineral component and the change will affect the distribution of ash in CFBC system. In a word, the computational results are in accordance with experimental results qualitatively but there are some differences quantitatively.  相似文献   

17.
Fluidized bed combustion (FBC) has the considerable advantage of being capable of burning high-sulphur fuels while achieving in situ sulphur capture by means of limestone addition. Unfortunately the efficiency of this process is limited, and limestone utilization in the range of 30–45% is not uncommon. In consequence, improving limestone utilization has long been an aim of FBC research. The principal directions this research has taken are the use of water (as liquid or vapour) to reactivate the spent sorbent, or mixing of chemical additives with the limestone to improve its utilization. Despite research stretching over the entire history of FBC combustion, there are still no working commercial applications of reactivation technology noted in the open literature. It is the aim of this paper to present some of the more important research undertaken in this field and to explore the major knowledge gaps that still exist in the area of sorbent reactivation.  相似文献   

18.
生物质流化床燃烧/气化的烧结特性与机理综述   总被引:1,自引:0,他引:1  
流化床燃烧/气化是生物质高效规模化能源利用的主要方式之一,由于生物质在较低温度下燃烧/气化时就容易发生床料烧结,影响了系统安全稳定运行,阻碍了能源利用效率的提高.系统地归纳了不同生物质在不同种类床料状态下燃烧/气化时烧结所需的特征温度,分析了生物质种类、碱金属含量、反应气氛与烧结温度之间的联系,结合相关研究,对生物质的烧结机理进行了分析和总结,对烧结温度预测方法和模型的优缺点进行了剖析和比较,对生物质燃烧/气化烧结机理进一步研究、预测模型的优化等提出了积极的建议,以期为相关研究的深入开展和生物质能规模化利用水平的提高提供有意义的参考.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号