Dense Phase transfer operation is used particularly for transfer of aggressive and difficult materials. Sand, cement and glass industry can be shown as example in this respect. Here, as the material is aggressive it does not strike the pipe wall sharply, but moves solidly by an air-product mix under high pressure of 2-5 bars and is product to far distances. For example, bulk cement tankers operate by this method. In this transfer method, unlike the fans with high flow rate in the dilute phase, the screw compressors and dehumidifiers at high flow rate are used.
High pressure air is delivered to the container full with the product to be transferred and then the high pressure air-product mix is transferred by the opening valve to the cyclone, silo or target mixer. This method is used especially if there is material in the process which may become fibrous or give damage to the characteristic of the product due to friction. The dense phase operates with instruments different than those of the dilute phase due to the transfer mechanism. The transport equipment are more resistant compared to those of the dilute phase. In this transfer performed by high pressure air, the thick-wall pipes and special basalt elbows are used.
In the pneumatic transfer, Centrifugal or Roots type blowers used as
air generators suck the air in the environment by vacuum and
develops thrust pressure by compressing the air. Due to relative
humidity of the air in the atmospheric environment, the water
particles serves as a good conductive during generation of the
pressure and, therefore, cause heating of the transfer air. This
temperature may occasionally reach up to 80oC depending on the
operating pressure of the process and drifting speed of the
If the target transport material has a structure susceptible to these temperatures, the operations of pre-cooling in the process and final cooling before introduction of the air in the process may be required. Because of the air temperature and speed, the most appropriate solution may be Densifier, Transporter and Dense phase transporter instead of complex structure of the dilute phase.