Pneumatic handling systems

F. Handling and feeding systems VII. Pneumatic conveyors Table 20 Survey of pneumatic handling systems... 

For higher pressures (up to 1.4 bar) so-called rotary gate (or rotary valve) feeders may be employed (Fig. 25), which function as air-locks. Similar devices may be used also for the discharge of the material from the pneumatic handling system. A special form of such feeders is intended for dealing with sticky materials which tend to remain adhering in the compartments or pockets of the rotor and is equipped with air jets that dislodge the material by blasts of air. 

Another, and somewhat arbitrary, subdivision distinguishes low-pressure, medium-pressure and high-pressure conveying. Various pneumatic handling systems are reviewed in Table 20. In the column "conveying speed" the settling rate of material particles is denoted by Wf. 

The pneumatic classification system should be designed to handle ha2ardous dust (28). A ha2ardous dust is one which, when finely divided and suspended in air in the proper concentration, bums, produces violent explosions, or is sufficiently toxic to be injurious to personnel health (see Air pollution control methods Powders, handling). At the least, almost any dust can be irritating to personnel because of inhalation or skin or eye contact. Fully oxidi2ed and hydrated materials are generally considered safe. 

NFPA 650 Standard for Pneumatic Conveying Systems for Handling Combustible Particulate Solids, 1998 edition. National Fire Protection Association, Quincy, MA. 

Recently, dry wire-pipe ESPs are being cleaned acoustically with sonic horns (Flynn, 1999). The horns, typically cast metal horn bells, are usually powered by compressed air, and acoustic vibration is introduced by a vibrating metal plate that periodically interrupts the airflow (AWMA, 1992). As with a rapping system, the collected particulate slides downward into the hopper. The hopper is evacuated periodically, as it becomes full. Dust is removed through a valve into a dust-handling system, such as a pneumatic conveyor, and is then disposed of in an appropriate marmer. 

Anon, Dynamics of Gas/Solids Systems, Pneumatic Handling ofBulkMat., Part A Fundamentals, Bulk Solids Handling Unit, Thames Polytechnic, London (1983)... 

Wypych, P. W., Optimising Uprating Pneumatic Transport Systems, Vat. Conf on Bulk Materials Handling, Yeppoon, Qld., IEAust. Proc., pp. 197-203... 

Wypych, P. W., and Arnold, P. C., Minimising Wear Particle Damage in Pneumatic Conveying Systems, Powder Handling Processing, 5(2) 129-134(1993)... 

There was no significant damage to equipment in the fire tests, and it was demonstrated that a Jet Airmix mixer may safely handle the mixing of RP formulations on a routine basis. Since a high risk of fire is always associated with any method of transfer of RP, a pneumatic conveying system [dynamic air, two phase positive pressure transfer system was evaluated to load RP into the Jet Airmix mixer. Electrostatic charge measurements were minimal and indicated the system was satisfactory to load the blender. 

A modern gas chromatograph, whether configured for packed or capillary column use, consists of several basic components. All of them must be properly chosen and operated for successful analysis. These are pneumatics and gas-handling systems, an injection device, an inlet, a column oven and column, a detector and a data system. Since the inception of GC in the 1950s, instrumentation has evolved significantly as new techniques and technologies were developed. This section provides an overview of the major components of a modern gas chromatograph, with details about how to choose components based on analytical needs, and applications. 

The probability of the formation of polymer agglomerates is appreciably increased by electrostatic interactions. This phenomenon is, inter alia, also known in the handling of polymer powders. Owing to the fact that the polymer particles are not electrically conductive, electrostatic charging occurs in pneumatic transport systems in an... 

P. Marjanovic, Modelling the transient behaviour of blow tank pneumatic conveying system. Powder handling and processing, Trans. Tech. Pub. 5 (3) (1993) 219-226. 

D.J. Mason, J. Li, P. Marjanovic, Numerical simulation of solids feeding in a gas-solids pneumatic transport system, Proceedings of the 3rd Israel Conference for Conveying and Handling of Particulate Solids, vol. 2, The Dead Sea, Israel, May 2000, pp. 10.93-10.101. 

Design of the raw material and fabricated product handling system has a major impact on the plant s manufacturing costs and housekeeping. It is based on the different materials used, annual volume of each material, number of different colors, production run lengths, etc. A properly designed pneumatic system generates plastic velocities of at least 5000 ft/min (1500 m/min). 

Although waste is considered as a material, in fact it is a mixture of materials, each one having its own handling characteristics, somehmes entirely different than those of the other components. There are several handling systems used to convey solid waste. The most widely used are steel plate, belt and vibrating conveyors, bucket elevators, and pneumatic systems. 

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