联合循环电站除尘技术进展

分析了整体煤气化联合循环(IGCC)和增压流化床联合循环(PFBC-CC)系统中除尘装置的工艺特点,并对各种除尘工艺发展现状进行了介绍.对工艺中用到的各种高温气体除尘装置如旋风分离器、颗粒床过滤器、刚性陶瓷过滤器、金属过滤器、湿式洗涤、静电除尘器等的特点进行分析,给出了各自的优缺点及研究进展情况.     

陶瓷滤管基体粉尘沉积状况SEM分析

将树脂包埋、固化技术成功应用在陶瓷滤管基体的SEM 分析上,能够在不破坏基体和粉尘沉积结构的情况下对滤材内的孔隙率、孔隙直径、颗粒直径、沉积量等微观参数进行测量和分析。使用压汞仪和X － 射线衍射仪（XRD） 对测量和计算结果进行了验证和分析,证明实验方法可靠,测量结果准确。SEM 测量结果表明尽管陶瓷滤管基体由相同尺寸的陶瓷颗粒制成,由于颗粒本身的不规则和堆积结构的随机性,基体内孔隙差别很大,这会导致局部的速度场和浓度场分布不均,引起粉尘沉积和阻力增加。随着脉冲反吹循环次数的增加,粉尘沉积有加剧并向内部延伸的趋势。     

循环过程中陶瓷滤材内粉尘沉积规律实验研究

The penetration and deposit of particles within the medium is thought to be one reason that the residual pressure drop of the rigid ceramic filter increase with cycle number. In this study, the change in the microstructure of a single layer ceramic filter candle during filtration-cleaning cycle was observed by scanning electron microscope (SEM) and the resistance property of the filter was monitored accordingly. The experimental results show that there exists a serious dust deposit within the filter medium, especially at the surface region. This should be responsible for the decrease of the filter permeability. The deposit law of dust in the filter medium during filtration-cleaning cycle was then studied by measuring the deposit depth, the deposit amount, the particles distribution within the medium, the size distribution of deposited particles, and so on. Particles migration and fine particles penetration were found to be the main reasons, for which dust deposit within the filter medium became aggravated with cycle number. Based on a differential form of Ergun equation, an expression for the pressure drop of a used ceramic filter was developed with a good agreement with experimental results. Then, the effect of dust deposit on the residual pressure drop was studied at the different face velocities and dust sizes. It was found that face velocity and dust size significantly influence dust deposit within filter medium, and then the operation performance of the filter.     

陶瓷过滤器脉冲反吹用喷嘴优化设计

The experimental study was carried out to optimize the nozzle shape and dimension for the pulse cleaning of a ceramic filter candle. A bench scale unit of ceramic filter consisting of four commercial filter elements was used to measure the traces of the transient pressure around the nozzle and the overpressure in the filter cavity during the pulse-jet injection of pulse gas. Overpressure in the filter cavity is related to the pulse cleaning force. Nozzle design is concerned to increase the overpressure at the open end of filter element of pulse cleaning inlet, as well as to minimize the consumption of pulse gas. Convergent nozzle induces more secondary flow and generates higher pulse cleaning effect than straight nozzle. Nozzles of different convergent ratio （ratio of outlet to inlet diameter of nozzle） by changing the convergent angle and height were tested. The outlet diameter of convergent nozzle seriously influences the cleaning effect. The optimum convergent ratio increases with the increase of pulse gas pressure The nozzle position （distance of nozzle tip from the open end of filter inlet） is also important to decide the nozzle dimension. Nozzle of large outlet diameter accepts high pressure of pulse gas to provide large overpressure in the filter cavity of top position by applying long distance.