GMC系列袋除尘器在水泥厂的使用措施与对策

介绍了GMC脉喷型袋除尘器的工作原理和技术特点，同时分析了水泥生产过程中烘干设备、立窑、回转窑窑尾和篦冷机等扬尘点的高温烟气特点。在此基础上，着重介绍不同工况条件下使用GMC系列高温脉喷型袋除尘器所采取的措施与对策．以正确引导高温喷吹型袋除尘器的设计选型和使用。     

陶瓷过滤器滤管脉冲反吹过程的流动特性

在由三根陶瓷滤管组成的实验装置上 ,利用热线风速仪对脉冲反吹时滤管外瞬态流场进行了测定 ,分析了喷吹压力、脉冲宽度、过滤气速和喷吹距离对滤管外流场的影响。随着离开滤管距离的增加 ,喷吹速度和回流速度逐渐减小。结果表明 ,回流现象和喷吹气流沿轴向的不均匀性是影响过滤器脉冲反吹性能的重要因素     

Distributions of age, thickness and gas velocity in the cake of jet pulsed filters—application and validation of a generations filter model

Different imperfections are observed with jet pulsed filters. They manifest themselves most obviously in the curve of the pressure drop versus time. A convex pressure drop curve indicates cake compaction. But jet pulsed filters frequently show a concave rise of the pressure drop curve. This phenomenon is due to a strongly nonuniform cake area load on the filter and it is generally attributed to incomplete cake removal. Incomplete cake removal takes place when only a fraction of the total filter area is cleaned at the end of a filter cycle or when patchy cleaning prevails. Patchy cleaning means that a jet pulse removes the entire filter cake of only a fraction of the exposed filter area except for a thin adhesive dust layer.In this paper a filter model is proposed in which the different classes of cake thickness are understood to result from different cake generations. A cake becomes one generation older when it survives the jet pulse cleaning at the end of a filtration cycle, although the area that is occupied by the cake on the filter medium is diminished by the jet pulse.This generations filter model can be used to find the distributions of age, thickness and gas velocities in the cake from steady-state operational data. The steady-state, periodic model provides a complete basis for the simulation of heterogeneous gas/solid reactions in the cake of jet pulsed filters.In the model intermediate cake build up during the cleaning procedure is considered. There redeposition of removed filter cake also takes place, and its extent is estimated. The model can also serve to determine from macroscopic process data, if the cleaning system of a filter installation operates in the undesirable mode of patchy cleaning.Experiments from a pilot plant for dry flue gas cleaning are presented and the generations filter model is validated with the experimental data.     

Pulse Jet Cleaning of Textile and Rigid Filter Media – Characteristic Parameters

To characterize the pulse cleaning of textile and rigid filter media in technical filter houses and test rigs, by now mainly tank pressure and valve opening time have been used as characteristic parameters. The pressure pulse formed, however, depends on the whole geometry of the plant so that these operation parameters do not allow a comparison between different technical systems. Thus, the question is raised – also for the development of new pulse jet systems – which parameters of a cleaning pulse are decisive for its performance. By knowing these parameters, an experimental setup could be adjusted in a way that it shows the same cleaning behavior like a filter house so that the laboratory filter tests are comparable to technical filter cycles. On a filter test rig which can be used for both textile and rigid filter media as well as on a pilot plant designed for Herding alpha filter candles, experiments concerning the influence of these different parameters on the cleaning behavior were performed. By inserting different orifices into the blow tube and varying the tank pressure and valve opening time, cleaning pulses of great variability were generated and the history of pressure drop over the filter medium or with candles even on the filter surface was recorded. The performance parameters maximum pressure pressure integral and pressure rise velocity of each pressure pulse were determined and compared with the cleaning efficiency achieved. As result of comprehensive regression analyses we found that especially the maximum pressure and the pressure rise velocity during the zero passage of a cleaning pulse are decisive for the cleaning result. The practical conclusion is that pulse jet systems should be optimized with regard to these parameters. The pressure integral however is not a significant performance parameter.     

Effective comminution of diatomaceous earth in a vertical type jet mill

Comminution characteristics of diatomaceous earth have been investigated in a vertical type jet mill of pilot plant scale; the diameter of the chamber of mill is 26.3 cm. Fluidization of the particles in the chamber has been proposed to enhance the comminution efficiency of the jet mill by promoting the effective contacting of powders with compressed air as well as the chamber wall. Effects of the pressures or densities of pulverizing-air and fluidizing-air and comminution time on the mean size of the particles and the rate of comminution have been examined. The statistical analysis of pressure fluctuations in the chamber of the mill has been utilized to predict the characteristics of the vertical-type jet mill taking advantage of the fluidization technique. The particle size and comminution rate have been correlated with the operating variables, respectively.     

陶瓷过滤器脉冲反吹时滤管外压力波形的测定与分析

利用压电式压力传感器测定了滤管外的压力波形,分析了喷吹压力、脉冲宽度等因素对滤管外压力的影响。实验结果表明,在脉冲反吹时滤管外附近区域的压力波衰减轻快,而离滤管壁一定距离后压力波则在过滤器内均匀传播。同时证明在脉冲及吹过程中,集气室对相邻滤管间相互影响具有重要作用。     

气流粉碎机粉碎室速度场研究

本文建立了气流粉碎机粉碎室结构与流动参数间的函数关系,确立了速度场的变化规律,所得结论不仅与Rink等人采用静压测孔推算的速度分布十分吻合,而且还得到作者用激光多普勒测速技术对流场进行速度测试的进一步验证.     

高温气体过滤除尘脉冲反吹再生过程的研究进展

叙述近年来高温气体过滤除尘技术的实验和理论研究进展,指出脉冲反吹再生过程是高温气体过滤除尘过程持续操作的关键。操作参数以及结构设计(包括喷嘴直径、喷嘴与文氏嘴之间的距离、喷嘴出口速度以及文氏嘴结构等)对除尘工艺过程和再生效果具有很大影响。分析了脉冲反吹过程中所涉及的传递现象数值模拟,以期更为深入地了解反吹再生过程的气流流动与能量传递规律,以指导和优化过滤装置的操作参数和结构设计。     

Experimental study of cake formation on heat treated and membrane coated needle felts in a pilot scale pulse jet bag filter using optical in-situ cake height measurement

Pulse-jet bag filters are frequently employed for particle removal from off gases. Separated solids form a layer on the permeable filter media called filter cake. The cake is responsible for increasing pressure drop. Therefore, the cake has to be detached at a predefined upper pressure drop limit or at predefined time intervals. Thus the process is intrinsically semi-continuous. The cake formation and cake detachment are interdependent and may influence the performance of the filter. Therefore, understanding formation and detachment of filter cake is important. In this regard, the filter media is the key component in the system. Needle felts are the most commonly used media in bag filters. Cake formation studies with heat treated and membrane coated needle felts in pilot scale pulse jet bag filter were carried out. The data is processed according to the procedures that were published already [Powder Technology, Volume 173, Issue 2, 19 April 2007, Pages 93-106]. Pressure drop evolution, cake height distribution evolution, cake patches area distribution and their characterization using fractal analysis on different needle felts are presented here. It is observed that concavity of pressure drop curve for membrane coated needle felt is principally caused by presence of inhomogeneous cake area load whereas it is inherent for heat treated media. Presence of residual cake enhances the concavity of pressure drop at the start of filtration cycle. Patchy cleaning is observed only when jet pulse pressure is too low and unable to provide the necessary force to detach the cake. The border line is very sharp. Based on experiments with limestone dust and three types of needle felts, for the jet pulse pressure above 4 bar and filtration velocity below 50 mm/s, cake is detached completely except a thin residual layer (100-200 μm). Uniformity and smoothness of residual cake depends on the surface characteristics of the filter media. Cake height distribution of residual cake and newly formed cake during filtration prevails. The patch size analysis and fractal analysis reveal that residual cake grow in size (latterly) following regeneration initially on the base with edges smearing out, however, the cake heights are not leveled off. Fractal dimension of cake patches boundary falls in the range of 1-1.4 and depends on vertical position as well as time of filtration. Cake height measurements with Polyimide (PI) needle felts were hampered on account of its photosensitive nature.     

中国超细粉碎和精细分级技术现状及发展

综述了中国超细粉碎与精细分级技术与设备的现状、近5年的进展 .20世纪90年代中期以来,中国超细粉碎和分级技术取得了显著进步,现已具备了研制和生产气流粉碎机、高速机械冲击式超细粉碎机、搅拌球磨机、振动球磨机、塔式搅拌磨、行星球磨机、高压射流磨、旋风自磨机等各类超细粉碎及涡轮式气流分级机和离心式水力分级机等设备的能力,并在流态化床式气流粉碎机、飓风自磨机、搅拌球磨机和砂磨机、行星球磨机、高压水射流磨机以及精细分级原理和分级设备等方面取得了一些进展,具有自主知识产权的新技术、新设备显著增多.指出中国目前在超细粉碎和精细分级领域仍然存在大型设备不足、工艺控制技术落后、磨耗和单位产品能耗偏高、特殊粒形超细粉体的生产工艺和设备落后等问题.最后对21世纪初中国超细粉碎和分级技术的主要发展趋势进行了展望.     

Druckstoßabreinigung textiler und starrer Filtermedien: Abreinigungsrelevante Parameter

Pulse Cleaning of Textile and Rigid Filter Media – Characteristic Parameters To characterize the pulse cleaning of textile and rigid filter media in technical filter houses and test rigs, by now mainly tank pressure and valve opening time have been used as characteristic parameters which are however dependent on the whole geometry of the plant and which therefore do not allow a comparison between different technical systems. Thus, the question is raised which parameters of a cleaning pulse are decisive for its performance. By knowing these parameters, an experimental setup could be adjusted in a way that it shows the same cleaning behavior like a filter house, so that the laboratory filter tests are comparable to technical filter cycles. On a filter test rig which can be used for both textile and rigid filter media as well as on a pilot plant designed for Herding alpha filter candles, experiments concerning the influence of these different parameters on the cleaning behavior were performed. The characteristic figures maximum pressure, pressure integral, and pressure rise velocity of each pressure pulse were determined and compared with the cleaning efficiency achieved. As result of comprehensive regression analyses we found that especially the maximum pressure and the pressure rise velocity during zero‐passage of a cleaning pulse are decisive for the cleaning result. The practical conclusion is that pulse jet systems should be optimized with regard to these parameters.     

On the Stability of Pulse‐Jet Regenerated‐Bag Filter Operation

Problems with the pulse‐jet bag filter operation have a direct influence on process plant operation and may result in loss of production time. Therefore, long‐term stable operation of the plant is desirable for both the manufacturers and operators. The effects of operating parameters are studied experimentally on filter operation with regeneration between the upper and lower pressure drop limits. Many combinations were identified when the filter operation derailed from stable to unstable operation on changing one of the operating parameters. Filtration velocity, pulse pressure, and the upper limit of pressure drop had the potential of creating instability. A threshold detachment overpressure existed below which the operation led to unstable conditions at a certain filtration velocity and which increased with increasing velocity.     

Non-damage deep etching of SiC by hybrid laser-high temperature chemical processing

SiC is considered as preferred material for micro-electro-mechanical system in the future. The excellent mechanical property and chemical stability make it difficult to perform deep etching. The hybrid laser-high temperature chemical etching is investigated to realize non-damage deep etching of SiC. The influences of defocus, laser pulse interval, laser intensity, and pulse number on etching depth are researched. The optimized laser parameter for SiC non-damage deep etching is laser intensity of 10 × 10⁹ W/cm² with a pulse interval of 10 ms. In order to analyze the interaction mechanism, the temperature field and laser-induced liquid jet in the liquid environment are calculated numerically. It is concluded that the material removal mechanism consists of laser heating vaporization during laser pulse, mechanical effect of laser-induced liquid jet impact between two adjacent laser pulses and chemical etching in laser-induced local high-temperature environment. The chemical reaction between SiC and mixture of HF, and HNO₃ solution produces gases and fluosilicic acid and effectively reduces the roughness of the modified layer making the surface smoother, and also removes the microcracks on the side wall of the etched region.     

Pulse jet cleaning of rigid filters: a literature review and introduction to process modelling

Dust abatement from hot gases is frequently performed using rigid filters. These filter elements are periodically cleaned by applying a reverse pulse of compressed air. The pulse generating system should yield a maximum jet momentum, while operating at the lowest possible pressure to reduce the consumption of air. In the following article, I Schildermans, J Baeyens and K Smolders present and review extensive literature data and theories.     

A novel process for preparation of ultra-clean micronized coal by high pressure water jet comminution technique

A novel process for the preparation of ultra-clean micronized coal is presented in this paper. High pressure water jet mill replacing the ball mill is employed for coal comminution in the new preparation process, which is the essential difference from the traditional one. To compare the new preparation process with the traditional one, the comparison experiments were performed, with froth flotation tests of the fine particles ground by both mills using 0# diesel oil and n-dodecane as collector, 2-octanol as frother, and sink–float separation tests using mixtures of carbon tetrachloride–benzene and carbon tetrachloride–bromoform as dense liquid. Different parameters including combustible recovery, ash content of the clean coal, separation efficiency, and energy consumption were investigated based on the two different preparation processes. The results show that the new preparation process has high combustible recovery, low ash content of the product, high separation efficiency, and low energy consumption compared with the traditional one.The comminution mechanism of high pressure water jet mill is introduced in this paper. The high pressure water jet comminution technique has great potential in coal pulverization, having the advantages of low energy consumption, low iron content, and low equipment wear.     

The use of a countercurrent jet mill in the production of insulating ceramics

The possibility of using a countercurrent jet mill in preparing molding powder to make insulating ceramics is considered. The process scheme is described and technical specifications of products are given. The auditors draw the conclusion that the stages of diluting clay in water and its milling, homogenization, and drying can be replaced by the stage of fine milling using a countercurrent jet mill. __________ Translated from Steklo i Keramika, No. 8, pp. 29–31, August, 2006.     

气流粉碎机的现状及技术进展

结合作者的实际工作经验，以及所接触的本行业的国内外先进技术，概述了当今粉体工业上使用的一些气流粉碎设备，阐述了当前国内外气流粉碎机的技术进展情况。     

Treatment of palm oil mill effluent by upflow anaerobic filtration

An upflow anaerobic filter (23 dm³ working volume) was used for the treatment of palm oil mill effluent. The filter was continuously operated for 215 days with organic loads ranging from 1·2 to 11·4 kg of chemical oxygen demand per cubic metre per day and hydraulic retention times from 15 to 6 days. The overall substrate removal efficiency was very high, up to 90% and the filter effluent contained almost no suspended solids. For all runs, the operation of the filter exhibited good stability for acidity and alkalinity, indicating that the use of buffer solutions would not be required. The methane concentration in the biogas, whose production varied from 20 to 165 dm³ per day, was about 60%. Daily gas production varied in the range 0·69–0·79 dm³ per gram of chemical oxygen demand removed.     

An investigation of carbon nanotube jet grinding

Since their observation in 1976 and 1991, carbon nanotubes (CNTs) have generated much interest due to their properties and potential applications. CNTs are tubular carbon molecules with remarkable mechanical, electrical, chemical and thermal properties, which make them useful in various applications. Industries producing CNTs via the fluidized bed chemical vapor deposition technique face challenges related to the size of CNT bundles. The two main challenges are agglomeration and agglomerate size distribution control. A solution to these challenges involves the use of jet mills to grind the CNT agglomerates. The goal of this study was to determine whether the nanotubes could be ground with air jets using a commercial jet mill and apply a two-parameter model to describe the grinding process. The present study has indicated that air-jet grinding of CNTs is feasible with a typical commercial jet mill. This paper presents the effect of operational parameters on the arithmetic mean diameter of the ground product. Sonic velocity through the grinding nozzles was required to obtain reasonable grinding rates and relatively narrow particle size distributions. This occurs at high air to solids feedrate ratios. Additionally, a simple attrition model can describe the grinding process in the spiral jet mill.     

惰性气体保护气流粉碎系统在化工行业的推广应用

从防燃、防爆、防氧化、环保及防热敏性多重性惰性气体保护气流粉碎系统的结构特点和技术要点出发,探讨了其在化工行业中的应用.