Conveying system

Perhaps the greatest stimulus for the development of such tools has been the proliferation of high angle wells in which deviation surveys are difficult and wireline logging services are impossible (without some sort of pipe conveyance system), and where MWD logging can minimise formation damage by reducing openhole exposure times. 

Rotary V lve Feeders. Devices known as rotary valve feeders are commonly used for circular or square configured outlets. These are particularly useful when discharging materials to a pneumatic conveying system where a seal is required to prevent air flow through the hopper outlet. The discharge rate is set by the speed of rotation of the vanes or pockets of the valve. 

A variety of specialized idlers are available. Examples are plastic disk catenary idlers for handling wet corrosive materials two roU idlers, where the roUs are oriented in a vee for lighter duty conveying system and suspended idler supports for severe service. In this last type, three to five idler roUs are linked end-to-end and suspended from conveyor frame stringers to form a catemary that cradles the belt. 

Dilute Phase Conveying. Dilute conveying systems, sometimes called disperse conveying or stream conveying, operate as positive pressure systems at pressures up to 100 kPa (14.5 psig), or as negative pressure systems (vacuum conveying) at pressures up to —50 kPa (—500 mbar). 

Dense phase systems are at cost disadvantage when multiple feed points are required, or when incremental compressed air for conveying is not available from existing sources. In the latter instance, the entire investment cost of an air compressor and associated auxiUaries must be allocated to the cost of the conveying system. 

M. V. Arastoopour, M. V. Modi, D. V. Punwani, and A. T. Talwalker,M Keview of Design Equations for Dilute Phase Gas-Solids Hori ntal Conveying Systems for Coal and Belated Material, Powder and Bulk SoHds Conference, Philadelphia, 1979. 

The capacity of a pneumatic-conveying system depends on (1) produc t bulk density (and particle size and shape to some extent), (2) energy content of the conveying air over the entire system, (3) diameter of conveying hne, and (4) eqmvalent length of conveying hue. 

FIG. 21-12 Types of air-conveying systems, a) Pressure, (h) Vacuum, (c) Pressure-vacuum, (d) Pressure vacuum unloading and transfer. (Whitlock, Inc.) (e) Fluidizing system. (Fuller Co.) (/) Blowtank. 

Hopper Trucks These trucks are used to transport by highway a wide variety of materials. Vehicle types range from the open-dumping kind to the closed type. Most common is the type that unloads by pressure differential into its own pneumatic-conveying system, which is temporarily connected to a storage silo. On this type of truck, the unloading of 18,100 kg (40,000 lb) of produces takes about 1 h, sometimes less. 

Pressure build-up Provide adequate venting and dust filtration on downstream of receiving vessel vent mill (risk of com-, Where liquefied gas (nitrogen or CO9 ) is used ponent failure, ensure adequate vent sizing and limit particularly in gas liquefied gas feed-rate to mill conveying systems). Internal pressure may also force product out of the mill. CCPS G-11 CCPS G-22 CCPS G-23 CCPS G-29... 

Heat build-up Replace screen with one correctly sized and/or due to too fine or clean screen blocked outlet, Install pressure indicator downstream and screen. upstream of mill for conveyed systems Measure temperature at strategic points in mill casing to detect and alarm product temperature rise CCPS G-12 CCPS G-23 CCPS G-29... 

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

Gerchow, Frank J., How to Select a Pneumatic Conveying System, Chemical Engineering, February 17, 1975. 

Perkins, Don E., Wood, Jim E., Design and Select Pneumatic Conveying Systems. Hydrocarbon Processing, March 1974. 

For higher differential pressures (or lower differential pressures where it is preferred not to use a fan), rotary positive-displacement blowers are used. These are excellent for conveying systems since they provide... 

Conveying systems are used to transport captured pollutants from processes to a collection point. 

These are mainly pneumatic conveying systems, in which impurities and solid waste, but also materials or goods, are transported by air flows. The systems categories are low-pressure, medium-pressure and high-pressure systems, depending on how heavy the impurities are that the system will transport. 

Design conveying system to convey captured contaminants away (separate tree). 

As a simple and efficient particle separation device, cyclone collectors can be used for anything from dust removal in a fluid stream to material collection in the fluid conveying system. However, the cyclone is not suitable or economical for the separation of extremely small particles (say, less than 1 /xm), which frequently occur in industrial processes. It is recommended that the size of particles to be separated in an industrial ventilation cyclone be in the region of around 10 to 100 p.m. However, for the purpose of aerosol sampling, the size of particles to be separated may be much less than 10 jxm. 

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