The mixing action in a continuous mixer is similar to that in a Banbury – type mixer. The
raw materials are fed into the mixer from hoppers. The rotors or “mixing screws” in
continuous mixers can be divided into three parts – screw conveyor, mixer and pumper.
The conveyer part of the rotor propels the ingredients to the mixing part of the rotor. The
overall forward movement of the material is actually obtained by the particular geometry
of the rotors and the constant change in material viscosity as its temperature increases
along the rotor (maximum where the mixing takes place).
The mixer part of the rotor is the place where the actual mixing takes place. The length of
the mixing chamber can be regulated by changing the discharge opening setting (This is one of the most important operating variables of the continuous mixer).
raw materials are fed into the mixer from hoppers. The rotors or “mixing screws” in
continuous mixers can be divided into three parts – screw conveyor, mixer and pumper.
The conveyer part of the rotor propels the ingredients to the mixing part of the rotor. The
overall forward movement of the material is actually obtained by the particular geometry
of the rotors and the constant change in material viscosity as its temperature increases
along the rotor (maximum where the mixing takes place).
The mixer part of the rotor is the place where the actual mixing takes place. The length of
the mixing chamber can be regulated by changing the discharge opening setting (This is one of the most important operating variables of the continuous mixer).
The mixer part of the rotor is the place where the actual mixing takes place. The length of
the mixing chamber can be regulated by changing the discharge opening setting (This is
one of the most important operating variables of the continuous mixer).
The pumping function of the rotors come into play at the end of the mixing section where
the material will be homogenous and plastic in character. This section is called the
Internal mixing
discharge zone. The pumping action of the rotors pushes the material downwards through
the discharge opening which functions like a valve.
Contrary to normal thinking, the rotor speed or the discharge opening have no influence
on the residence time of the material in the mixing chamber. This is only governed by the
feed rate of the feeding equipment upstream. The feed section of the screws are so
designed that they are constantly starved, so that the ingredients are conveyed practically
without pressure in the mixing chamber.
An important aspect of the mixer is the temperature and pressure profiles inside the
mixing chamber. Both these parameters are maximum at the mixer part of the rotor. And
though the pressure dies down at the other two parts of the rotor, the temperature
maintains itself in the pumping part of the rotor also. Maximum power consumption also
happens at the mixer part of the rotor. The mixing rate, viscosity and material properties
and flow are determined by these parameters. These parameters need to be controlled to
get a non – scorched good “mix” compound.
the mixing chamber can be regulated by changing the discharge opening setting (This is
one of the most important operating variables of the continuous mixer).
The pumping function of the rotors come into play at the end of the mixing section where
the material will be homogenous and plastic in character. This section is called the
Internal mixing
discharge zone. The pumping action of the rotors pushes the material downwards through
the discharge opening which functions like a valve.
Contrary to normal thinking, the rotor speed or the discharge opening have no influence
on the residence time of the material in the mixing chamber. This is only governed by the
feed rate of the feeding equipment upstream. The feed section of the screws are so
designed that they are constantly starved, so that the ingredients are conveyed practically
without pressure in the mixing chamber.
An important aspect of the mixer is the temperature and pressure profiles inside the
mixing chamber. Both these parameters are maximum at the mixer part of the rotor. And
though the pressure dies down at the other two parts of the rotor, the temperature
maintains itself in the pumping part of the rotor also. Maximum power consumption also
happens at the mixer part of the rotor. The mixing rate, viscosity and material properties
and flow are determined by these parameters. These parameters need to be controlled to
get a non – scorched good “mix” compound.
No comments:
Post a Comment