Device for focussing particles suspended in a gas stream

A device for controlling the motion of particles suspended in a gas stream, comprising:

• a pipe, through which at least a fraction of the gas stream flows, having an inlet end for receiving said fraction of the gas stream and an outlet end for expelling said fraction of the gas stream;
• means for supplying an AC voltage having an amplitude and a frequency;
• means for supplying a DC voltage;
• means, coupled to the means for supplying an AC voltage and to the means for supplying a DC voltage and positioned within said pipe, for generating an inhomogeneous electric field for focussing the particles suspended in the gas stream so they concentrate into a narrow axial region in the center of the pipe while they remain suspended in the gas stream, wherein the means for generating is located outside of the narrow axial region;
• said means for generating comprising a plurality of electrodes, including a first set of electrodes and a second set of electrodes, the first set of electrodes is located outside of a first region of the narrow axial region, the second set of electrodes is located outside of a second region of the narrow axial region that is separate from and spaced downstream of the first region;
• wherein the first set of electrodes are disposed around the first region of the narrow axial region and define a first diameter of the narrow axial region along the first region;
• and
• wherein the second set of electrodes are disposed around the second region of the narrow axial region and define a second diameter of the axial region which is less than the first diameter of the narrow axial region, thereby resulting in focussing of a set of particles suspended in the gas stream that is flowing consecutively past the first set of electrodes and then past the second set of electrodes.

A device for controlling the motion of particles suspended in a gas stream, comprising:

• a pipe, through which at least a fraction of the gas stream flows, having an inlet end for receiving said fraction of the gas stream and an outlet end for expelling said fraction of the gas stream;
• means for supplying an AC voltage having an amplitude and a frequency;
• means for supplying a DC voltage;
• means, coupled to the means for supplying an AC voltage and to the means for supplying a DC voltage, for generating an inhomogeneous electric field for focussing the particles suspended in the gas stream by generating a force upon the particles urging the particles into a narrow axial region in the center of the pipe while remaining suspended in the gas stream, wherein the means for generating is entirely located outside of the narrow axial region;
• wherein said means for generating comprises a plurality of electrodes, including a first set of electrodes and a second set of electrodes, the first set of electrodes is located along a first region of the narrow axial region, the second set of electrodes is located along a second region of the narrow axial region that is separate from and spaced downstream of the first region;
• wherein the first set of electrodes are disposed around the narrow axial region and define a first diameter of the narrow axial region along the first region;
• and
• wherein the second set of electrodes are disposed around the narrow axial region and define a second diameter of the narrow axial region along the second region, thereby resulting in further focussing of a set of particles suspended in the gas stream that is flowing consecutively past the first set of electrodes and then past the second set of electrodes.

A device for focussing particles from an axial region that is aligned with a direction of flow of a gas stream in which the particles are suspended into a narrow axial region that is contained in said axial region, comprising:

• a pipe having an axis, an inlet end for receiving the gas stream, and an outlet end for expelling the gas stream, the axial region being aligned along said axis of said pipe and inside of said pipe;
• AC voltage generating means for generating an AC voltage;
• DC voltage generating means for generating a DC voltage;
• field generating means, positioned within said pipe, for generating an inhomogeneous electric field within said axial region that is aligned along the axis of the pipe such that said inhomogeneous electric field generates a force upon any particle that is within the axial region but outside of the narrow axial region urging said any particle toward the narrow axial region, said field generating means including a plurality of electrodes all of which are located outside of said narrow axial region, wherein at least a first two AC electrodes of said plurality of electrodes are connected to opposite polarity terminals of said AC voltage generating means and oppose one another across a first segment of said axial region and at least a first two DC electrodes of said plurality of electrodes are connected to opposite polarity terminals of said DC voltage generating means and oppose one another across a second segment of said axial region;
• wherein at least a second two AC electrodes of said plurality of electrodes are structured for connection to opposite polarity terminals of said AC voltage generating means and oppose one another across a second segment of said axial region and at least a second two DC electrodes of said plurality of electrodes are structured for connection to opposite polarity terminals of said DC voltage generating means and oppose one another across said second segment of said narrow axial region, said second segment of said narrow axial region is separate from and spaced downstream of said first segment;
• wherein a portion of the narrow axial region inside said first segment of said narrow axial region has a first diameter which is larger than a second diameter of a portion of said narrow axial region that is inside said second segment.

A device for focussing particles that are suspended in an axial region of a flowing gas stream into a narrow axial region that is aligned with and contained in said axial region, comprising:

• a pipe having an axis, an inlet end for receiving the gas stream, and an outlet end for expelling the gas stream, said axial region and said narrow axial region being within the pipe and aligned with said axis;
• means for focussing charged and uncharged particles that are inside said axial region and outside of said narrow axial region into said narrow axial region, comprising means for generating an inhomogeneous electric field at every point that is inside of said axial region, said inhomogeneous electric field having an AC component and a DC component in a focussing region that is inside of said axial region and outside of said narrow axial region, such that at for any particle at any point in the focussing region said inhomogeneous electric field induces forces upon said any particle such that a time average of said forces urges said any particle from the focussing region towards said narrow axial region, whereby all particles in said axial region are focussed into said narrow axial region;
• said means for focusing comprises a plurality of electrodes, including a first set of electrodes and a second set of electrodes, the first set of electrodes is located along a first segment of the axial region, the second set of electrodes is located along a second segment of the axial region that is separate from and spaced downstream of the first segment;
• wherein the first set of electrodes are disposed around the axial region and define a first diameter of the axial region along the first segment;
• and
• wherein the second set of electrodes are disposed around the axial region and define a second diameter of the axial region along the second segment, thereby resulting in a further focusing of a set of particles suspended in the gas stream that is flowing consecutively past the first set of electrodes and then past the second set of electrodes.