| In the addition case,boosters are located every 3 mt. along the entire lenght of the conveying pipeline and the air flow rate to each booster is 560 Lt./min. In the case, the air velocity reaches 48 mt./sec. by the end of pipeline. An important point to note is that in the case of a booster system of this type, the velocity at all points in the pipeline will be higher than in the case where the boosters are not used. It the clear that the use of continuously operating boosters makes velocity contol in the pipeline very difficult. In the case illustrated above it can be seen that even if the system operates in dense phase initially, the velocity at the end of the pipeline indicates that the system will be operating in diluite phase by that stage. Even if the air flow rates to each booster are halved, the exit velocity will still reach 30 mt/sec. A degree of control over the air velocity could be achieved by careful stepping of the pipeline at appropriate positions along the pipeline length. This is laways a useful tecnique for controlling the air velocity. A further consideration for continuous air injection system is the level of gas flow rate required at each injection point to ensure reliable conveying. Clearly, the quantity of air will depend on the material being conveyed..... |
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