Assisted discharge

The temperature of heated fuel when delivered into customer s storage will depend upon the length of time in transit, or the measures of preheat given to a rail tank car to assist discharge. These heat sources should not be overlooked in calculations. 

Powder discharge process Gravity-assisted Impeller assisted BM Gravity-assisted discharge process HSDB Impeller required to discharge material from high-shear mixing vessel... 

Keywords Air blast Air assist Discharge coefficient Effervescent Electrostatic Hat fan nozzles Full cone Hydraulic Hollow cone Rotary SMD Spray angle Spray impact Spray pattern Swirl Twin fluid Ultrasoiuc... 

An air-assisted discharger is designed to aerate only a thin layer of bulk solid above the permeable membrane. For such a system to work properly the air must be able to easily exit the bin through its outlet when solids are discharged. This usually means that discharge cannot be restrained, such as is the case with a flood-loaded feeder. Instead, a full port ball or dome valve is used to discharge slugs of bulk solid from the bin. 

Sometimes with rate limiting powders an air permeation system or air-assisted discharge can be used to increase flow rate and thereby limit the outlet size. Some powders are also more suitable to being handled in a fluidised state, which also limits the outlet size. 

If, to the other extreme, the discharge rate is insufficient for the downstream process and changing the speed of the feeder does not correct the problem, the solution is to enlarge the outlet or add an air permeation system. If the mismatch between actual and required flow rates is so great that these alternatives are not capable of solving the problem, a fluidised or air-assisted discharge should be considered. 

Thus, if O is the fraction of the overpotential assisting discharge, the activation energy, AG, which would be required if the process were to occur reversibly is reduced to (AG - activation energy, AGli, is increased to (AGti + (1 - a)nF(E - E )). We may therefore express the forward and backward rates in the form... 

Figure C2.18.3. Relationship between ion-assisted etching and directionality in plasma etching, (a) Demonstration of the synergy between ion bombardment and reactive species during ion-assisted etching, (b) Ions incident on an etched feature. This situation prevails in glow discharges when the feature dimensions are much less than the plasma sheath thickness. Reproduced from [35]...

Plasmaspray, or discharge-assisted thermospray, is a modification of thermospray in which the degree of ionization has been enhanced. 

In conventional disk filters, cake discharge is usually performed by a scraper blade, for cakes thicker than 10 mm, or sometimes by a tapered roU air blowback is often used to assist the discharge. High pressure sprays also have been used for cake discharge. 

The Gaudfrin disk filter, designed for the sugar industry and available in Prance since 1959, is also similar in design to a vacuum disk filter but it is enclosed in a pressure vessel with a removable Hd. The disks are 2.6 m in diameter, composed of 16 sectors. The cake discharge is by air blowback, assisted by scrapers if necessary, into a chute where it may be either reslurried and pumped out of the vessel or, for pasty materials, pumped away with a monopump without reslurrying. 

Cake discharge occurs at atmospheric pressure by the action of a toU or a scraper, assisted by blowback. The cloth may be washed by a spray before the cycle starts again. Filtering areas range up to 8 m and dmm diameters up to 2 meters. The necessity for large seals limits the operating pressure to less than 300 kPa, typically. Cake thickness can be from 2 to 150 mm, depending on machine size, and the speed of dmm rotation up to 2 rpm, usually from 0.3 to 1 rpm. Apphcations occur in the manufacture of pharmaceuticals, dyestuffs, edible oils, and various chemicals and minerals. 

Flow Aids. Flow aids are devices used to assist in discharging materials from a bin or other storage container. The best use of such a device is when gravity alone is insufficient or impractical to provide rehable discharge. However, in many instances, flow aid devices are ovemsed in appHcations in which they are either uimecessary or create new problems. 

In most cases, CVD reactions are activated thermally, but in some cases, notably in exothermic chemical transport reactions, the substrate temperature is held below that of the feed material to obtain deposition. Other means of activation are available (7), eg, deposition at lower substrate temperatures is obtained by electric-discharge plasma activation. In some cases, unique materials are produced by plasma-assisted CVD (PACVD), such as amorphous siHcon from silane where 10—35 mol % hydrogen remains bonded in the soHd deposit. Except for the problem of large amounts of energy consumption in its formation, this material is of interest for thin-film solar cells. Passivating films of Si02 or Si02 Si N deposited by PACVD are of interest in the semiconductor industry (see Semiconductors). 

---