Pneumatic transport system design

Design a positive pressure dilute-phase pneumatic transport system to transport 900 kg/h of sand of particle density 2500 kg/m and mean particle size 100 gm between two points in a plant separated by 10 m vertical distance and 30 m horizontal distance using ambient air. Assume that six 90° bends are required and that the allowable pressure loss is 0.55 bar. 

These problems in turn were hampering the successful design and/or operation of long-distance pneumatic conveying systems and hence, the future potential of this method of transport to a wide variety of industries. 

Although transport of specimens from the patient to the clinical laboratory is often done by messenger, pneumatic tube systems have been used to move the specimens more rapidly over long distances within the hospital. Hemolysis may occur in these systems unless the tubes are completely filled and movement of the blood tubes inside the specimen carrier is prevented. The pneumatic tube system should be designed to eliminate sharp curves and sudden stops of the specimen carriers, because these factors are responsible for much of the hemolysis that may occur. With many systems, however, the plasma hemoglobin concentration may be increased, and the serum activity of red cell enzymes, such as lactate dehydrogenase, may also be increased. Nonethe-... 

Bends complicate the design of pneumatic dilute phase transport systems and when designing a transport system it is best to use as few bends as possible. Bends increase the pressure drop in a line, and also are the points of most serious erosion and particle attrition. 

The insulation strategy for the device was vacuum packaging, which is in line with other small scale system designs described above. A micro-fixed bed steam reformer coupled to a preferential oxidation reactor was then developed by Shah and Besser with a theoretical power output of 0.65 W. The heat supply of the combustion reaction was simulated by the platinum heater, as shown in Figure 9.19. The BASF commercial steam reforming catalyst was milled to 70 pm and introduced into the device by pneumatic transport, filter structures retained the particles within the device. Fleating experiments revealed that the steam reformer could not be heated to more than 230 °C by the electric heater, which had reached a temperature of 550 °C even under these conditions. This was attributed to heat losses by various mechanisms. Insulation by fibreglass decreased the heat losses substantially. The conclusion of... 

For application in fluidization and fluid-particle systems, the attrition index is probably the most important particle characteristic. The particle attrition can affect the entrainment and elutriation from a fluidized bed and thus subsequently dictate the design of downstream equipment. The attrition in a pneumatic transport line can change the particle size distribution of the feed material into a fluidized bed reactor and thus alter the reaction kinetics. Davuluri and Knowlton (1998) have developed standardized procedures to evaluate the Attrition Index employing two techniques, solids impaction on a plate and the Davison jet cup. The two test units used are shown in Figs. 6 and 7. They found that these two test techniques are versatile enough to be applicable for a wide range of materials, such as plastic, alumina, and lime-... 

H.S. Muralidhara, W.J. Rebello, R.P. Kiishnan and C.Y. Wen, Saltation velocity correlations for the design of long-distance horizontal pneumatic coal transport systems, Int. Powder Bulk Solids Handling Processing, Huladelphia, 1979. 

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