Reverse Rotation Dual Power Impellers

In gas-liquid systems, one of the reasons that the power of the impeller is lower with the gas on than with the gas off is that the gas bubbles collect behind the impeller blade. This streamlines the blade, reducing power. Looking at Fig. 45, speculation can be made on what would happen if one were to fill up and streamline the back of the impeller with solid material. What happens is that with no gas rate. Fig. 46, the impeller draws less horsepower with the back of the blade streamlined than with the back of the blade flat. 

When the gas is turned on, the flat impeller blade has a K factor, which is the ratio of impeller power with gas on to power with gas off, and changes markedly with gas rate, typical of impellers of that type, while the impeller with the streamlined back of the blade has much less change in power with gas rate. 

The schematic relationship shown in Fig. 46 gives a wide variety of power consumption availabilities without gas and with gas by having the mixer and motor capable of being reversed electrically, and opens up a wide variety of process options. 

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