Clogging pressure

A large bubble divides the liquid into left and right parts. The bubble forms two menisci in contact with the liquid and the bulk part in direct contact with the channel wall. 

Let us assume the bubble to have quasistatic motion, that is, the velocity of the bubbles is nearly zero, and the bubble remains close to equilibrium for all bubble positions. The channel is also assumed to be smooth, that is, free from sharp corners. The pressure at the left and right of the bubble is Pi and P, respectively. The pressure difference across the bubble is AP ,. The surface tension for the liquid-gas, solid-liquid, and solid-gas interface is ajg, Tsi, and respectively. The gas pressure inside the bubble is P,. At the left meniscus (x = Xi and R2 are the main radii of curvature. The pressure difference AP = P, - P across the interface according to the Young-Laplace equation is 

For circular tube, the interface will be spherical, and two radii of curvature are expressed as 

At the taper section, the contact angle (9) will change by the taper angle (0,) as 

For the left interface, the contact angle increases due to the entry of the interface inside the contraction section. Similarly, for the right interface, the contact angle decreases due to the exit of the interface from the contraction section. Hence, using Young-Laplace equation for the left meniscus, it can be written as 

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Permeability of the filter layer Gases need to flow through the bed in good contact with the filter bed material. An excess of fine material in the filter bed may cause clogging, pressure build-up and blowout of bed material... 

Code rated pressure vessels are not deliberately operated above the rated operating pressure. However, clogged pressure relief nozzles combined with a pressure generating reaction can result in overpressuring. 

Perform a full scale experiment, and compare the results (filtering efficiency, clogging, pressure drop and energy requirements) to the previous performances of the facility. 

The clogging pressure is defined as the minimal external pressure that must be supplied to push the bubble through the channel. Hence, clogging pressure is the maximal of the position-dependent pressure drop across the bubble ... 

A good summary of the behavior of steels in high temperature steam is available (45). Calculated scale thickness for 10 years of exposure of ferritic steels in 593°C and 13.8 MPa (2000 psi) superheated steam is about 0.64 mm for 5 Cr—0.5 Mo steels, and 1 mm for 2.25 Cr—1 Mo steels. Steam pressure does not seem to have much influence. The steels form duplex layer scales of a uniform thickness. Scales on austenitic steels in the same test also form two layers but were irregular. Generally, the higher the alloy content, the thinner the oxide scale. Excessively thick oxide scale can exfoHate and be prone to under-the-scale concentration of corrodents and corrosion. ExfoHated scale can cause soHd particle erosion of the downstream equipment and clogging. Thick scale on boiler tubes impairs heat transfer and causes an increase in metal temperature. 

In diatomaceous-earth filtration, the powdered filter aid is built upon a relatively loose septum to screen out suspended soHds. The filter becomes clogged, and pressure losses become excessive backwashing is then necessary. The smallest removable particle is 0.5—1 p.m (see Diatomite). 

By far the greatest number of instaUations is for the removal or recoveiy of mostly small concentrations of acidic and other components from air, hydrocarbons, and hydrogen. Hundreds of such plants are in operation, many of them of great size. They mostly employ either packed or tray towers. Power requirements for such equipment are small. When the presence of solid impurities could clog the equipment or when the pressure drop must be low, spray towers are used in spite of their much larger size for a given capacity and scrubbing efficiency. 

Vent system Test system back pressure before use inoperable, Flow indication or pressure drop indication or clogged. ACGIH 1986 CCPS G-3 CCPS G-22 CCPS G-23 CCPS G-29... 

Similarly, at lower currents, the volume of arc plasma is loo small I ) and so is the clogging effect. The pressure and volume of the quenching gas can be adjusted to interrupt the current now also at current zero. All these adjustments are pre-set and sealed by the manu-facturer. 

This condition cannot be corrected on pumps with an enclosed impeller. You need to relax the restricted discharge flow on the pump. The problem could be a clogged downstream filter, a closed discharge valve, an over-pressurized header (back-pressurizing the pump), or a... 

Internal Re-circulation Operation / Design / Maintenance Internal Re-circulation results from something in the discharge side of the pump strangled valve, clogged filter, over-pressurized header, check-valve installed backwards. 

This type of seal has the rotary component and face mounted outside the seal chamber. The springs and drive elements are outside the pumped liquid. This reduces the problems associated with corrosion and the accumulation of pumped product clogging the springs. This seal is popular in the food processing industry. The pumped liquid arrives to the inside diameter of the faces and seals toward the outside diameter. The environment outside the pump approaches the OD of the face union. Pressures are limited to about 35 psig. Sometimes this. seal can be mounted either inside or outside the pump. This seal is easy to install, adjust, and maintain. It permits easy access and cleaning of the pump internal parts, often required in the food processing industry. 

Clogged air filter. A elogged air filter may be deteeted by noting an inerease in the pressure drop through the filter. 

The line to the pressure gauge tends to become clogged during the reaction. 

Another feature of an extruder is the presence of a gauze filter after the screw and before the die. This effectively filters out any inhomogeneous material which might otherwise clog the die. These screen packs as they are called, will normally filter the melt to 120-150 fim. However, there is conclusive evidence to show that even smaller particles than this can initiate cracks in plastics extrudates e.g. polyethylene pressure pipes. In such cases it has been found that fine melt filtration ( 45 p.m) can significantly improve the performance of the extrudate. 

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