Gravity chambers

The loading chamber is similar to the low-gravity chamber we described in detail previously (Tulp et al., 1980a). In Figure 10a the loading... 

Operating costs of the various devices vary from essentially no cost for gravity chambers with weir ontlet controls, to significant electrical and maintenance costs for high-speed centrifuges. Some periodic costs for clean-out of solids accumulations may be required with most of die devices. Relative positioning of the devices by operating cost is essentially in the order of capital cost shown in Table 3.3-1. 

The first form of aerosol modifier is a spray chamber. It is designed to produce turbulent flow in the argon carrier gas and to give time for the larger droplets to coalesce by collision. The result of coalescence, gravity, and turbulence is to deposit the larger droplets onto the walls of the spray chamber, from where the deposited liquid drains away. Since this liquid is all analyte solution, clearly some sample is wasted. Thus when sensitivity of analysis is an issue, it may be necessary to recycle this drained-off liquid back through the nebulizer. 

Another common system is the fixed knife mill. This consists of a chamber containing fixed knives and a rotating three-armed spider that shreds the fmit by forcing them against the fixed knives. Fmit are gravity fed into the chamber from an opening in the top. Small holes under the knives permit the mash to fall through to a conveyor. 

For low pressure pipelines that have ports open to the atmosphere, eg, sewers or closed effluent culverts, samplers are designed to sample through manholes. In a typical system, the Hquid is lifted through a suction line into the sampling chamber under vacuum. When filled, the vacuum shuts off, and the sample drains into a sample jar. A secondary float prevents any Hquid from reaching the vacuum pump. The suction line then drains by gravity back to the source. 

The elimination of air from the chamber and complete steam penetration of the load is of critical importance. This may be accompHshed by gravity displacement or prevacuum techniques. 

The gravity-displacement-type autoclave rehes on the relative nonmiscibility of steam and air to allow the steam that enters to rise to the top of the chamber and fill it. The air is pushed out through the steam-discharge line located at the bottom of the chamber. Gravity-displacement autoclaves are utilized for the sterilization of Hquids and for unwrapped nonhoUow medical instmments at 134°C. 

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. 

U Length of gravity settling chamber in direction of gas flow m ft ... 

Flyash - Flyashes are finely divided matter generally entrained in flue gases that arise from combustion. Particles range from 1 /im in size on down. This is not within the operational range of gravity settling chambers. Wet... 

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