Pneumatic classifier for tobacco and method

A vertical lift pneumatic classifier for separating light tobacco leaf particles from heavier tobacco stem particles in a single pass of combined tobacco particles across a separation chamber, and being adjustable for use with a full range of tobacco particle sizes and shapes in a threshing system, said classifier comprising:

• a vertically extending separator chamber;
• a variable speed, vaned rotor located at a first end of said separator chamber for projecting a stream of intermixed light leaf and heavier stem particles across said separator chamber from said first end toward a second end thereof;
• a leaf removal duct disposed proximate an upper portion of said separator chamber;
• a stem removal chute located at said second end of said separator chamber, and at an elevation below that of the vaned rotor;
• a static, planar air distribution screen extending at a downward incline across said separator chamber substantially from the chamber first end to a point near the stem removal chute at the chamber second end at an elevation below said vaned rotor, said screen surface permitting the introduction of forced air therethrough and into the separator chamber for the purpose of lifting and separating the tobacco leaf particles from said stem particles, the openings of said screen being sized to provide greater air velocities near the chamber first end and progressively lower air velocities as the screen extends to the chamber second end;
• forced air supply means for directing forced air through said air distribution screen and into the separator chamber;
• air diffuser vanes associated with said forced air supply means for establishing multiple streams of inlet forced air, with the highest velocity stream being proximate the separator chamber first end, and with the lowest velocity being proximate the second end of said chamber so that the varied decreasing velocities of the forced air input streams are correlated with the decreasing velocity of the stream of leaf and stem particles propelled across the separator chamber;
• whereby the velocity of the fed tobacco particles and the forced air velocities along said air distribution screen are independently adjustable is response to the characteristics of the fed tobacco particles to provide, for all particle characteristics, peeling off of a substantial portion of the light leaf particles in an upward direction proximate said first end and projection of the heavier stem particles substantially along a descending path to said stem removal chute.

A single pass tobacco particle classifier for separating lighter tobacco leaf particles from heavier tobacco stem particles and comprising:

• a separator chamber having opposed ends, an upper portion, and a lower portion;
• means for projecting a combined dispersing stream of light tobacco leaf particles and heavier tobacco stem particles in an arc-shaped path across said chamber, from one end toward another second end, with the velocity of said stream decreasing as it approaches the second other end;
• means for applying to said combined projected particle stream a plurality of upwardly moving air streams having differing velocities for gently separating lighter tobacco leaf particles from heavier tobacco stem particles in a single pass of said combined particle stream across said air streams;
• the higher velocity air streams engaging faster portions of the combined particle streams proximate said one end and across said projected particle stream and the lower velocity air streams engaging slower portions of the combined projected particle stream proximate said second other end and across said projected stream.

A method of separating light tobacco leaf particles from heavier stem particles in a single pass, vertical lift pneumatic classifier including a vertically extending separator chamber having opposite ends, tobacco particle feed means disposed proximate one of said ends of the separator chamber for projecting a stream of intermixed light leaf and heavier stem particles into and across the separator chamber toward the other end thereof at an initial velocity, the stream velocity decreasing as the stream progresses across the chamber, forced air inlet supply means for directing forced air upwardly through and across the length of the separator chamber between said ends, light leaf removal means in an upper portion of said separator chamber and stem removal means in a lower portion of said separator chamber, said method comprising the steps of:

• projecting the stream of intermixed particles into and across the separator chamber at a predetermined velocity and angular position;
• dividing the inlet forced air directed upwardly into respective high, medium, and low velocity streams, directing the high velocity forced air stream through the projected stream of particles immediately after they enter the separator chamber at said one end, and directing the medium velocity stream through the central portion of the separator chamber and through the medial portion of the stream of particles, and directing the low velocity stream adjacent the other end of the separator chamber and through the stream of particles as they approach the other end of the separator chamber, and
• thus correlating the high-to-low velocities of the separate air streams with the corresponding decreasing velocities of the stream of intermixed particles being fed across the separator chamber to gently separate the light leaf particles from the heavier stem particles, so that the light leaf particles rise to said light leaf removal means and the stems fall to said stem removal means on a single pass of the intermixed stream across said chamber.

A method for separating various types of light tobacco leaf particles from various types of heavier tobacco stem particles in a single pass across a separating air stream including the steps of:

• combining said particles in a particle stream;
• projecting said stream in an arc-shaped path;
• projecting at least three independent streams of air moving at different velocities transversely across said path and through said projected combined particle stream with a higher velocity air stream engaging said projected combined particle stream at an upstream position thereof, corresponding to a high particle stream velocity, and sucessively lower velocity air streams engaging said projected particle streams at downstream positions thereof corresponding to successively lower particle stream velocities;
• and
• independently adjusting the velocity of the particle stream and of the at least three separate air streams to correlate all said respective velocities as a function of the particular type of tobacco particles to be separated.

A vertical lift pneumatic classifier for separating light tobacco leaf particles from heavier tobacco stem particles in a combined stream of particles, and being adjustable for use wth a full range of fed tobacco particle sizes and shapes in a threshing system, said classifier comprising:

• a vertically extending separator chamber;
• tobacco particle feed means located at a first end of said separator chamber for projecting a stream of intermixed light leaf and heavier stem particles across said separator chamber from one end thereof toward another;
• leaf removal means disposed proximate an upper portion of said separator chamber;
• stem removal means located at a second opposite end of said separator chamber, opposite said tobacco particle feed means, and at an elevation below that of the tobacco particle feed means;
• a forced air distribution surface extending across the lower portion of said separator chamber substantially from the chamber first end to the chamber second end, said surface including openings permitting the introduction of upwardly directed forced air from underneath the surface and into the separator chamber for the purpose of lifting and separating the tobacco leaf particles;
• forced air supply means for directing forced air upwardly through said air distribution surface and into the separator chamber;
• means associated with said forced air supply means and said air distribution surface for establishing along the length of said air distribution surface from said first end of said chamber to said second end, a plurality of upwardly directed air streams having varying velocities with the higher velocity air streams being proximate the separator chamber first end and the lower velocity air streams being proximate the chamber second end, so that the velocity of the respective upwardly directed forced air streams is correlated with the decreasing velocity of the stream of leaf and stem particles projected across the separator chamber;
• and
• means for selectively adjusting the tobacco particle feed velocity and the angular orientation of the fed particle stream with respect to the horizontal;
• the progressively changing velocities of the forced air streams being adjustable independently of the velocity and angular orientation of the projected particle stream in response to the characteristics of the tobacco particles to provide, for all tobacco particle characteristics, peeling off of a substantial portion of the light leaf particles in an upward direction proximate said first end and projection of the heavier stem particles substantially along a descending path across said chamber to said stem removal means.

A vertical lift pneumatic classifier for separating light tobacco leaf particles from heavier tobacco stem particles in a combined stream of particles, and being adjustable for use with a full range of tobacco particle sizes and shapes, said classifier comprising:

• a vertically extending separator chamber;
• a variable speed, vaned rotor located at a first end of said separator chamber for projecting a stream of intermixed light leaf and heavier stem particles across said separator chamber from said first end toward a second end thereof;
• a leaf removal duct disposed proximate an upper portion of said separator chamber;
• a stem removal chute located at said second end of said separator chamber, and at an elevation below that of the vaned rotor;
• a static, planar air distribution screen extending at a downward incline across said separator chamber substantially from the chamber first end to a point near the stem removal chute at the chamber second end at an elevation below said vaned rotor, said screen surface pemitting the introduction of forced air therethrough and into the separator chamber for the purpose of lifting and separating the tobacco leaf particles from said stem particles, the openings of said screen being sized to provide greater air velocities near the chamber first end and progressively lower air velocities as the screen extends to the chamber second end;
• forced air supply means for directing forced air through said air distribution screen and into the separator chamber;
• air diffuser vanes associated with said forced air supply means for establishing multiple streams of inlet forced air, with the highest velocity stream being proximate the chamber first end, so that the velocities of the forced air input are correlated with the decreasing velocity of the stream of leaf and stem particles projected across the separator chamber;
• whereby the velocity of the fed tobacco particles and the forced air velocities along said air distribution screen are independently adjustable in response to the characteristics of the fed tobacco particles to provide, for all particle characteristics, peeling off of a substantial portion of the light leaf particles in an upward direction proximate said first end and projection of the heavier stem particles substantially along a descending path to said stem removal chute.

A tobacco particle classifier for separating lighter tobacco leaf particles from heavier tobacco stem particles in a combined stream of particles and comprising:

• a separator chamber having opposed ends, an upper portion, and a lower portion;
• means for projecting a combined stream of light tobacco leaf particles and heavier tobacco stem particles in an arc-shaped path across said chamber, from one end toward another second end, with the velocity of said stream decreasing as it approaches the second end,
• means below said particle stream for applying to and across said projected combined particle stream a plurality of upwardly moving air streams having differing velocities for gently separating lighter tobacco leaf particles from heavier tobacco stem particles;
• the higher velocity air streams engaging faster upstream portions of the projected combined particle stream thereacross and the lower velocity air streams engaging slower downstream portions of the projected combined particle stream thereacross.

A method of separating light tobacco leaf particles from heavier stem particles in a combined stream of particles in a vertical lift pneumatic classifier including a vertically extending separator chamber having opposite ends, tobacco particle feed means disposed proximate one of said ends of the separator chamber for projecting a stream of intermixed light leaf and heavier stem particles into and across the separator chamber toward the other end thereof at an initial velocity, the stream velocity decreasing as the stream progresses across the chamber, forced air inlet supply means for directing forced air upwardly through and across the length of the separator chamber between said ends, light leaf removal means in the upper portion of said separator chamber and stem removal means in the lower portion of said separator chamber, said method comprising the steps of:

• projecting the stream of intermixed particles into and across the separator chamber at a said initial velocity and predetermined angular position;
• dividing the inlet forced air directed upwardly into respective high, medium, and low velocity streams, directing the high velocity forced air stream through the projected stream of particles immediately after they enter the separator chamber at said one end, directing the medium velocity stream through the central portion of the separator chamber and through the medial portion of the projected stream of particles, and directing the low velocity stream adjacent the other end of the separator chamber and through the projected stream of particles as they approach the other end of the separator chamber, and
• thus correlating the high-to-low velocities of the separate air streams with the corresponding decreasing velocities of the projected stream of intermixed particles being fed across the separator chamber to gently separate the light leaf particles from the heavier stem particles, so that the light leaf particles rise to said light leaf removal means and the stems fall to said stem removal means.

A method for separating various types of light tobacco leaf particles from various types of heavier tobacco stem particles in a combined stream of particles including the steps of:

• combining said particles in a particle stream;
• projecting said stream in an arc-shaped path;
• projecting at least three independent streams of air moving at different velocities transversely across said path and through said combined particle stream with a higher velocity air stream engaging said projected combined particle stream at an upstream position thereof, corresponding to a high particle stream velocity, and successively lower velocity air streams engaging said particle stream at downstream positions thereof corresponding to successively lower particle stream velocities to separate leaf particles from stem particles;
• and
• independently adjusting the velocity of the particle stream and of the at least three separate air streams to correlate all said respective velocities as a function of the particular type of tobacco particles to be separated.

A particle classifier for separating lighter particles from heavier particles in a single pass of a stream of combined particles across a separator chamber and comprising:

• a separator chamber having opposed ends, an upper portion, and a lower portion;
• means for projecting a combined stream of lighter particles and heavier particles in an arc-shaped path across said chamber, from one end toward another second end, with the velocity of said stream decreasing as it approaches the second other end,
• means for applying to said projected particle stream a plurality of upwardly moving air streams having differing velocities for gently separating lighter particles from heavier particles in a single pass of said projected particle stream across said air streams;
• the higher velocity air streams engaging faster portions of the projected combined particle stream proximate said one end and across said projected stream and the lower velocity air streams engaging slower downstream portions of the projected combined particle stream proximate said second end and across said projected stream.

A particle classifier for separating lighter particles from heavier particles in a stream of combined particles in a separator chamber and comprising:

• a separator chamber having opposed ends, an upper portion, and a lower portion;
• means for projecting a combined stream of lighter particles and heavier particles in an arc-shaped path across said chamber, from one end toward another second end, with the velocity of said stream decreasing as it approaches the second other end,
• means for applying to said projected particle stream a plurality of upwardly moving air streams having differing velocities for gently separating lighter particles from heavier particles in a single pass of said projected particle stream across said air streams;
• the higher velocity air streams engaging faster portions of the projected combined particle stream proximate said one end and across said projected stream and the lower velocity air streams engaging slower downstream portions of the projected particle stream proximate said second end and across said downstream portions of said projected stream.