Conveying distance

Despite the little experimental data, there are two models available in the literature. Adams etal. (1992) considered dense phase conveying. They tried to predict the amount of attrition as a function of conveying distance by coupling a Monte Carlo simulation of the pneumatic conveying process with data from single-particle abrasion tests. Salman et al. (1992) focused on dilute phase conveying. They coupled a theoretical model that predicts the particle trajectory with single particle impact tests (cf. Mills, 1992). 

However, this mode of flow usually is limited to conveying distances of L < 500 m. The Group D materials that possess wide size distributions (especially a considerable amount of fines) and/or unusual particle shape (e.g., crushed coal, petroleum coke, crushed bath, rice hulls) usually are not suited to low-velocity conveying. In these cases, the options are dilute-phase or single-slug dense-phase (i.e., these materials usually are too coarse for bypass conveying). However, when long distances are involved, dilute-phase may be the only practical option. 

Material Wt per cu ft Conveying Distance Vclocitv ft/sec Pressure Factor Conveying Distance Velocity (ft/scc)... 

Lengths of screw conveyors usually are limited to less than about 150 ft when the conveying distance is greater than this, a belt or some other kind of machine should be chosen. The limitation of length is due to structural strength of the shaft and coupling. It is expressed in terms of the maximum torque that is allowable. Formulas for torque and power of screw conveyors are given in Table 5.4 and are applied to selection of a conveyor in Example 5.3. 

When conveying plastics a properly designed system is to take the shortest distance. The shortest distance between two points is a straight line. The maximum conveying distance is usually 800 equivalent ft (244 m). A gradual upward slope is never better than a vertical lift. When the plastic passes through a 45° or 60° elbow, it ricochets back and forth creating turbulence that destroys its momentum. 

Establish the conveying distance and path, and the operating environment. 

Conveying distances. Carefully taking into account elbows, vertical distances, and flex-hose connections. 

The example is solved in two steps first, the saltation velocity is calculated, and second, the energy losses due to every aspect of the particles moving in the airstream inside the pipe are evaluated to estimate the total pressure drop needed for the particles to complete the conveying distance. 

The power required to drive screw conveyors depends on the length of the conveying path, the handling rate (throughput), the bulk density of the material, the pitch of the helix, and the resistances due to the nature of the material to be handled. The values listed in Table 19 are based on a pitch s = 0.75 D, loading (p = 0.2, bulk density 5 = 1.5t/m and circumferential velocity of the helix V = 1. Om/second. The figures under Pmotor indicate the power consumption for various horizontal conveying distances of up to 30m. 

A look at the above-mentioned configuration possibilities lead to a first determination of the parameters given by the layout of the plant, especially the conveying height and total conveying distance. 

For approximately 10 m conveying distance. Attention Each bulk material may show, different behaviour. ... 

Material to be conveyed Bulk density (kgdm-3) Conveying height (m) Conveying distance (m) Particle size Material characteristic Transporting capacity (kgh ) Suction- and loading system... 

The basic design of screw feeders depends on the material characteristics, the capacity required, the conveying distance, the weight of the material resting on the feeder screw, the dimensions of the feeder opening, and the power available. Screw feeders are... 

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