Particle penetration

Table 13 can be used as a rough guide for scmbber collection in regard to minimum particle size collected at 85% efficiency. In some cases, a higher collection efficiency can be achieved on finer particles under a higher pressure drop. For many scmbbers the particle penetration can be represented by an exponential equation of the form (271—274)... 

Deep Bed Filters. Deep bed filtration is fundamentally different from cake filtration both in principle and appHcation. The filter medium (Fig. 4) is a deep bed with pore size much greater than the particles it is meant to remove. No cake should form on the face of the medium. Particles penetrate into the medium where they separate due to gravity settling, diffusion, and inertial forces attachment to the medium is due to molecular and electrostatic forces. Sand is the most common medium and multimedia filters also use garnet and anthracite. The filtration process is cycHc, ie, when the bed is full of sohds and the pressure drop across the bed is excessive, the flow is intermpted and solids are backwashed from the bed, sometimes aided by air scouring or wash jets. 

The grade efficiency T of most collectors can be expressed as a function of the aerodynamic particle size in the form of an exponential equation. It is simpler to write the equation in terms of the particle penetration Pf (those particles not collected), where the fractional penetration = 1 — T, when T is the fractional efficiency. The typical collection equation is... 

Some large-particle penetration 24 hr or longer sample required in clean areas for mass measurement automated version relatively untested in remote locations... 

FIGURE 13.15 Particle penetration as a function of the Deutsch number. 

Figure 18 [28] shows the variation of the particle speed and the potential energy of the silicon wafer in the collision process. The dashed line means the speed of the particle in the vertical direction and the black one indicates the variation of potential energy of the silicon disk. When the particle penetrates into the wafer surface, its vertical speed becomes lower and lower. Once the particle reaches the deepest position, the speed of the particle becomes zero and the potential energy of the silicon wafer increases to the highest one, and... 

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

The central element of this reactor is an elongated channel in which small catalyst particles can be filled to give a mini-packed bed (Figure 3.20) [79, 80]. Gas streams enter this reaction zone as a mixture via an interleaved channel section, which also prevents the small particles penetrating the gas-feed channels. A similar type of microstmctured frit is placed at the end of the packed bed for the same function. 

Figure 30 shows the results of an experiment in which a solution of Q-CdS was fractionated by exclusion chromatography in a column of sephacryl-gel This column material has holes which the smaller particles penetrate and reside in for some time. The first fraction therefore contains the larger particles. The upper part of the figure shows the absorption spectrum of the starting material, and the lower part the spectra of six fractions. The first fraction has an unstructured spectrum beginning at... 

With animal cells, the whole virus particle penetrates the cell, being carried inside by endocytosis (phagocytosis or pinocytosis), an active cellular process. We describe some of these processes in detail later in this chapter. 

Particles Penetrate Into Bubble Roof Due to Taylor Instability When Penetration Completely Pierces Bubble - Bubble Splits... 

The design of a cross-flow filter system employs an inertial filter principle that allows the permeate or filtrate to flow radially through the porous media at a relatively low face velocity compared to that of the mainstream slurry flow in the axial direction, as shown schematically in Figure 15.1.9 Particles entrained in the high-velocity axial flow field are prevented from entering the porous media by the ballistic effect of particle inertia. It has been suggested that submicron particles penetrate the filter medium and form a dynamic membrane or submicron layer, as shown in... 

When the particle inertia overcomes the surface-tension-induced force, the particle will penetrate the bubbles. Recognizing that particle penetration may not lead to bubble breakage, details of bubble instability due to particle collision are given in Chen and Fan (1989a, b). 

In mouth breathing, only 10-15% of 15 pm particles penetrate through the larynx to the intrathoracic TB region. Particles reaching the TB region are considered to be inhalable (Lippmann, 1977 Miller et al., 1979). 

In the second type of filtration, depth or deep-bed filtration, the particles penetrate into the pores of the filter medium, where impacts between the particles and the surface of the medium are largely responsible for their removal and retention. This configuration is commonly used for the removal of fine particles from very dilute suspensions, where the recovery of the particles is not of primary importance. Typical examples here include air and water filtration. The filter bed gradually becomes clogged with particles, and its resistance to flow eventually reaches an unacceptably high level. For continued operation, it is therefore necessary to remove the accumulated solids, and it is important that this can be readily achieved. For this reason, the filter commonly consists of a bed of particulate solids, such as sand, which can be cleaned by back-flushing, often accompanied by... 

Bed filters provide an example of the application of the principles of deep bed filtration in which the particles penetrate into the interstices of the filter bed where they are trapped following impingement on the surfaces of the material of the bed. 

A quarter of a century ago the author stepped into Jens Oddershede s office and asked for support on a problem involving computation with atomic wave functions in connection with a new theoretical scheme to treat stopping of charged particles at intermediate speed. This visit resulted in two related publications, two joint papers and a number of follow-up studies by Jens and several others. In 1989 a Sanibel Symposium was devoted to aspects of the penetration of charged particles through matter, and since then, quite a few quantum chemists have joined the community of theoreticians dealing with particle penetration. 

Niels Bohr, a pioneer in both disciplines, emphasized the significance of classical vj. quantal arguments in particle penetration. Not the least in view of the complexity of ab initio computations in this area, such considerations keep being relevant. This note adds new points to an old discussion based on recent developments. 

Mix Penetration Strength. The susceptibility of separators to particle penetration is characterized by mix penetration strength. During the winding of the spiral wrap construction considerable mechanical pressure is applied to the cathode-separator—anode interface. Any loose particle could be forced through the separator and short the cell. The mix penetration strength should be at least 100 kgf/mil for separators used in lithium-ion cells. 

SOx can react with other compounds in the atmosphere to form small particles. These small particles penetrate deeply into sensitive parts of the lungs and can cause or worsen respiratory disease and aggravate existing heart disease. EPAs NAAQS for particulate matter (PM) are designed to provide protection against these health effects. 

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