Gravity conveying

This result was supported by the material s excellent air-gravity conveying performance (Wypych and Arnold, 1985a). Based on these results, it would be reasonable to assume that this material would be suited to fluidized dense-phase. 

Shaft furnaces are usually refractory-lined vertical cylinders, in which gravity conveys solids and liquids to the bottom and by-product gases to the top. Examples are cupolas, blast furnaces, and lime kilns. 

Dilute This is a fully expanded condition in which the solids particles are so widely separated that they exert essentially no influence upon each other. Specifically, the solids phase is so fuUy dispersed in the gas that the den sity of the suspension is essentially that of the gas phase alone (Fig. 12-29). Commonly, this situation exists when the gas velocity at all points in the system exceeds the terminal setthng velocity of the solids and the particles can be lifted and continuously conveyed by the gas however, this is not always true. Gravity settling chambers such as prilling towers and countercurrent-flow spray diy-ers are two exceptions in which gas velocity is insufficient to entrain the sohds completely. 

A gas-sohds contacting operation in which the sohds phase exists in a dilute condition is termed a dispersion system. It is often called a pneumatic system because, in most cases, the quantity and velocity of the gas are sufficient to lift and convey the sohds against the force of gravity. Pneumatic systems may be distinguished by two characteristics ... 

Tanks with conical bottoms discharge cakes by gravity and those with dished bottoms have a spade that rakes and conveys the cake towards the outlet. Hence, the conical types require more headroom as compared to the dished type having the same filtration area. Conical tanks also have often an additional scavenging plate at the lower part of the cone to filter the residual slurry heel that remains below the main plates. The slurry heel that remains at the very bottom of the tank is removed through a special dip pipe to avoid discharging a wet cake. To facilitate better cake... 

Subsurface drains include any type of buried conduits that convey and collect aqueous discharges by gravity flow (Figure 16.11). Water collected in a storage tank or a collection sump is then pumped for further treatment. Filters are usually needed in drain systems to prevent fine particles from causing clogging. 

The specific equipment used for each step depends on the incinerator type and the physical and chemical characteristics of the wastes the incinerator is designed to bum. Wastes are fed into the incinerator in batches or in a continuous stream. Liquid wastes are often pumped and atomized into fine droplets that bum more easily. Solid wastes may be fed into the incinerator in bulk or in containers using a conveyer, a gravity system, or a ram feeder.8... 

Hyperforming A hydrodesulfurization process in which the catalyst moves by gravity down the reactor and is returned to the top by a solids conveying technique known as hyperflow. Developed by the Union Oil Company of California in 1952 and first operated commercially in 1955. 

The Alpine pin disc mill shown in Figure 2.11 is a form of pin mill and consists of two vertical steel plates with horizontal projections on their near faces. One disc may be stationary whilst the other disc is rotated at high speed sometimes, the two discs may be rotated in opposite directions. The material is gravity fed in through a hopper or air conveyed to the centre of the discs, and is thrown outwards by centrifugal action and broken against of the projections before it is discharged to the outer body of the mill and... 

All single-screw extruders have several common characteristics, as shown in Figs. 1.1 and 1.2. The main sections of the extruder include the barrel, a screw that fits inside the barrel, a motor-drive system for rotating the screw, and a control system for the barrel heaters and motor speed. Many innovations on the construction of these components have been developed by machine suppliers over the years. A hopper is attached to the barrel at the entrance end of the screw and the resin is either gravity-fed (flood-fed) into the feed section of the screw or metered (starve-fed) through the hopper to the screw flights. The resin can be in either a solid particle form or molten. If the resin feedstock is in the solid form, typically pellets (or powders), the extruder screw must first convey the pellets away from the feed opening, melt the resin, and then pump and pressurize it for a down-... 

Washing experiments have been conducted on a pilot-scale rayon washing line that employs the rain-pan technique of gravity-flow wetting. In this system, precision-drilled, stainless-steel pans are used to "rain" measured quantities of solutions onto a batt of cotton. The batt is conveyed by a perforated stainless-... 

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