(2) dense phase conveying:  

The conveying process solid content of 10 to 30 kg/m3 or the solid-gas ratio greater than 25. The operating gas velocity is low with higher pressure. Now the mature pump equipment storehouse has the conveying distance reaching at above 500 m, suitable for long-distance transportation, but this device has many valves the pneumatic, electric devices are quire a lot. The delivery pressure is high and all pipes need wear-resisting material. The intermittent aeration tank is under the dense phase conveying. It adds the particles partially into the pressure tank and blow some air into it until the inside tank reaches at a certain pressure, open the material valve, and put the granular material into the pipeline transport. The pulse conveyor usually sends the compressed air into the tank, then blows the material at a  loose state; Another frequency is 20 ~ 40 min - 1  pulse compressed air flow blows into the transporting pipe inlet and forms in the pipe arranged alternately small segments of stock column and small gas column, nudged along by air pressure.